- Email: [email protected]
Perioperative and Anesthesia Management
C H A P T E R 1 4 Perioperative and Anesthesia Management Kenneth D. Candido, MD Teresa M. Kusper, DO Lauren Bonzelaar, MD
1 Introduction Obstructive sleep apnea/hypopnea syndrome (OSAHS) is a growing health care concern with many potentially detrimental consequences and important anesthetic implications. A rise in obesity among the population of the United States corresponds with an upswing in the prevalence of OSAHS.1 Over the last two decades, the prevalence of OSAHS increased from 26.4% to 33.9% in males and from 13.2% to 17.4% in females.1 An elevation in the body mass index (BMI) of one standard deviation increases the likelihood of coexisting OSAHS by a factor of four.2 In the morbidly obese population, the incidence of obstructive sleep apnea (OSA) is approximately 55% in women and 77% in men.3 Undiagnosed and/or untreated OSA leads to an increased risk of adverse perioperative events, specifically serious pulmonary complications: difficult mask ventilation, difficult direct laryngoscopy or fiber-optic intubations, desaturation and/or airway obstruction, aspiration pneumonia, acute respiratory distress syndrome, or even death.4 The airway obstruction in OSAHS patients results from a decrease in the upper airway muscle tone during sleep; airway narrowing due to the deposition of adipose tissue; and resultant increase in size of pharyngeal structures: the uvula, tonsils, tonsillar pillars, tongue, aryepiglottic folds, and the lateral pharyngeal walls (Fig. 14.1). As a result, the shape of the pharynx changes from a long transverse (lateral) and a short anterior–posterior axis into a narrower ellipsoid with a shorter transverse and a longer anterior–posterior axis. This change in shape impairs the action of the anterior pharyngeal airway dilators: the tensor veli palitini, genioglossus, and hyoid muscles (Fig. 14.2).5 A substantial number of patients seen in the operative units may have undiagnosed and untreated OSAHS. Recent reports have shown that approximately one-quarter of patients undergoing elective surgery have OSAHS, and over 80% of these cases are undiagnosed.6 High prevalence of undiagnosed OSAHS necessitates utmost vigilance, as well as prevention and early recognition of potentially devastating complications. The inability to intubate the patient, respiratory obstruction after tracheal extubation, and severe respiratory depression and respiratory arrest after the administration of sedatives and narcotics are some of the biggest concerns for anesthesiologists. Gupta et al. compared the occurrence of perioperative
complications in OSA (n = 101) and non-OSA patients (n = 101) after a hip or knee replacement and reported 39% and 18% complication rates (hypoxemia, hypercapnia, delirium) in the two groups, respectively.7 These results are corroborated by a number of other large studies, which demonstrate an increased likelihood of perioperative respiratory complications in patients undergoing various types of surgical procedures.8–10 Practice guidelines for the perioperative management of patients with OSAHS published by the American Society of Anesthesiologists (ASA) recommend the use of a scoring system to estimate a risk for perioperative complications from OSAHS, which incorporates three factors: (1) the severity of OSAHS, (2) the invasiveness of the surgery and anesthesia, and (3) the requirement for postoperative opioids (Table 14.1).11 Patients with an overall score of 5 or greater have an increased risk of perioperative complications. The rate of possible complications varies between different types of anesthesia provided. Memtsoudis et al. assessed perioperative outcomes in 30,024 patients diagnosed with OSAHS who underwent an orthopedic surgery between 2006 and 2010 under neuraxial and/or general anesthesia.12 The authors found lower rates of perioperative complications (pulmonary and cardiac and need for blood products) and improved postoperative outcomes (mechanical ventilation, intensive care unit [ICU] admission, length and cost of hospitalization) in patients under neuraxial anesthesia (16.0%) compared with general (17.2%) or combined neuraxial-general anesthesia (18.1%) and concluded that the neuraxial anesthesia may be a more beneficial option for patients with OSA.12 Respiratory compromise can also occur after regional anesthesia as shown by a retrospective study of 206 patients with OSA scheduled for an orthopedic surgery in an outpatient setting, where 34% of the patients experienced hypoxemia postoperatively.13 Despite those results, Sabers et al. demonstrate that presence of OSA does not increase the risk of adverse events or unforeseen hospital admissions in patients undergoing procedures in the outpatient center.14 Thus the Society for Ambulatory Anesthesia concluded that patients diagnosed with OSA can be selected for an outpatient procedure if the following criteria are met: comorbid conditions are managed, patients are able to use their continuous positive airway pressure (CPAP) device postoperatively, and the postprocedural pain can be adequately managed with 81
82
Section E Anesthesia for OSA/HS
Velopharynx or nasopharynx
Tensor palatine
Tensor palatine
Oropharynx
Genio glossus Hyoid muscles
Genio glossus
Velopharynx or nasopharynx Oropharynx
Hyoid muscles Laryngopharynx or hypopharynx
Airspace
Airspace
Laryngopharynx or hypopharynx
B
A
FIG. 14.1 (A) The action of the most important dilator muscles of the upper airway. The tensor palatine, genioglossus, and hyoid muscles enlarge the nasopharynx, oropharynx, and the laryngopharynx, respectively. (B) Collapse of the nasopharynx at the palatal level, the oropharynx at the glottic level, and the laryngopharynx at the epiglottic level. (Modified from Benumof JL: Obstructive sleep apnea in the adult obese patient: implications for airway management. J Clin Anesth 2001;13[2]:144–56, with permission.)
Area (cm2)
A
Anterior
B
Area (cm2)
3.54
4.09
3.00
3.00 Posterior
FIG. 14.2 The effects of a 5-mm change in the anteroposterior (AP) diameter of the airway on airway cross-sectional area is shown for two equally elliptical airways with different lateral/AP ratios. (A) The lateral/AP ratio = 0.5. (B) The lateral/AP ratio = 2. The lateral dimension of each ellipse was held constant. The solid line represents the starting area (3 cm2 in both ellipses), and the dotted line represents the area after a 5-mm increase in the AP diameter. The area change is greater in the ellipse with a more lateral orientation (B). (From Leiter JC: Upper airway shape. Is it important in the pathogenesis of obstructive sleep apnea? Am J Respir Crit Care Med 1996;153:894–8, with permission.)
nonopioid medications.15 After an extensive review of the available scientific literature, the ASA developed specific guidelines and recommendations for the perioperative care of patients diagnosed with OSA (Table 14.2).11
2 Preoperative Assessment of the Patient Whenever possible, the patient should be evaluated in a preoperative clinic several days before the planned surgery. The evaluation should include a review of the current and previous medical records, an interview of the patient, and a physical examination. Frequently, in the event of an emergency procedure or elective surgeries done in the outpatient centers, an evaluation by an anesthesiologist does not take place until immediately before the procedure. This
unfortunately precludes recognition and presurgical management of medical conditions such as sleep apnea. A careful review of all medical records is very important. Reviewing old medical records can be particularly useful with regard to previous anesthetic history, which may reveal airway difficulties, prolonged emergence, an unusual response to anesthetic agents, and the postoperative course. All coexisting medical conditions and treatments should be noted with special focus on the respiratory and cardiovascular organ systems. Any workup that has been done specific to OSAHS (polysomnographic testing, cardiac and pulmonary studies) should be checked, as it may provide valuable information regarding the severity of the disease. Use of CPAP or mouth appliances for the treatment of OSAHS should be investigated, and patients should be encouraged to bring CPAP equipment with them to the hospital on the day of their surgery. A detailed history from the patient and bed partner, if possible, helps in the identification of patients with undiagnosed OSAHS. The patient should be asked about the quality of sleep, frequent awakening, energy level in the morning, and daytime sleepiness and fatigue. The bed partner might offer information related to snoring and apneic episodes during the night. Several tools are available to screen the surgical patients for the presence of OSA: the Berlin Questionnaire, ASA Checklist, and STOPBANG. These tools assess presence of snoring, pauses in breathing, arousals, or choking; daytime somnolence manifested by fatigue or drowsiness despite sufficient sleep; high blood pressure; or specific physical characteristics (BMI >35 kg/m2, neck circumference >17 inches in men and >16 in women, age, gender, structural abnormalities of the orofacial passages). Many OSAHS patients have several coexisting diseases due to hypoxic episodes and obesity. A thorough physical examination is critical with a special focus on the physical characteristics such as body habitus, neck thickness, facial features including presence of a beard, mouth opening, and
CHAPTER 14 Perioperative and Anesthesia Management
83
Table 14.1 Summary of the Recommendations for the Perioperative Care of OSA Patients Developed by the American Society of Anesthesiologists I. Preoperative evaluation
II. Inpatient/ outpatient surgery
III. Preoperative preparation
IV. Postoperative management
V. Criteria for discharge to unmonitored settings Adapted from
Collaboration between anesthesiologists and surgeons is advised to develop a perioperative plan for patients with suspected sleep apnea Preoperative evaluation should include a review of past medical records, interview with the patient and/or family, and physical examination Sleep studies should also be reviewed if available Determination should be made after careful assessment of (1) presence of OSA, (2) anatomic and physiologic derangements, (3) comorbidities, (4) nature of surgery, (5) type of anesthesia, (6) need for postoperative opioids, (7) patient’s age, (8) adequacy of postoperative monitoring, and (9) capabilities of the outpatient center Careful selection of the intraoperative medications to minimize the risk of respiratory compromise Use local anesthetics or peripheral nerve blocks with or without moderate sedation for superficial procedures Continuous monitoring by capnography of the ventilator status in the presence of moderate sedation due to increased risk of airway obstruction Administer CPAP or oral appliance during sedation in patients previously using the devices Secure airway during general anesthesia and deep sedation Use neuraxial anesthesia (spinal/epidural) for peripheral procedures Extubate after a full reversal of the neuromuscular blockade Extubate in the lateral, semi-upright, or other nonsupine position Consider using regional analgesia to avoid using systemic opioids Evaluate risks and benefits of using neuraxial analgesia using opioid only or opioid–local anesthetic mixture versus local anesthetic only Avoid or use with caution continuous background infusions of medication when using patient-controlled analgesia (PCA) with systemic opioids Consider using nonopioid analgesics to reduce the requirement for narcotic medications Exercise caution when combining benzodiazepines and barbiturates, as they increase the risk of respiratory depression Judicious use of supplemental oxygen, as it may also suppress respiratory drive Use CPAP or noninvasive positive pressure ventilation in patients who were using them preoperatively Keep patients in the nonsupine position throughout the recovery process Use continuous pulse oximetry after transfer from the recovery unit into stepdown or telemetry In the event of hypoxemia, frequent, or severe airway obstruction, apply nasal CPAP or noninvasive positive pressure ventilation Postpone discharge until patients are no longer at risk of respiratory compromise Monitor the adequacy of oxygen saturation on room air while patient is sleeping
11
tongue size. The importance of a detailed cardiovascular examination cannot be overemphasized. One should have a low threshold for obtaining an electrocardiogram (ECG) and/or echocardiogram when a suspicion of compromised cardiovascular function arises, and severe cases should be referred to a specialist before an elective surgery. Hypoxic events are associated with several potentially detrimental cardiovascular derangements. For example, patients with moderate to severe OSAHS are nearly three times more likely to have nocturnal cardiac arrhythmias compared with non-OSAHS patients.16 Systemic hypertension is present in 50% of OSAHS patients and is more prevalent with increasing severity of OSAHS.17 Special attention must also be given to the airway of the patient to recognize features predictive of potentially difficult airway management. Frequently, OSA patients have a large tongue and a thick neck, and the probability of a difficult tracheal intubation rises from 5% when the neck circumference is 40 cm to 35% when the neck circumference is 60 cm.18 Moreover, the commonly seen excessive adipose
tissue in the interscapular region (“buffalo hump”) causes misalignment of the oral, pharyngeal, and tracheal axes during direct laryngoscopy. Determining whether tracheal intubation should be performed with the patient awake or under general anesthesia must be individualized on the basis of a methodical, complete airway examination (Table 14.3).
2.1 Premedication Sedatives and narcotics have a propensity to exacerbate the sleep-related apneic episodes and may impair lifesaving arousal in patients with OSAHS. Benzodiazepines and barbiturates preferentially decrease neural input to the upper airway dilating muscles, leading to airway obstruction.19 Anxiolytic drugs such as midazolam should only be administered when close monitoring of the patient by appropriate personnel is possible. This means that the drug should not be given until the patient is about to enter the operating room for surgery. Narcotic medications specifically are associated with a high risk of respiratory depression. Even small doses of narcotics
84
Section E Anesthesia for OSA/HS
Table 14.2 Scoring System for Calculation of Perioperative Risk in Patients With OSAHS‡
Table 14.3 Components of the Preoperative Airway Physical Examination
A. Severity of sleep apnea based on sleep study (or clinical indicators if sleep study not available). Point score ______ (0–3).*† 0. None (AHI = 0–5) 1. Mild (AHI = 6–20) 2. Moderate (AHI = 21–40) 3. Severe (AHI > 40) B. Invasiveness of the surgery and anesthesia. Point score ______ (0–3). 0. Superficial surgery under local or peripheral nerve block without sedation 1. Superficial surgery with moderate sedation or general anesthesia or peripheral surgery with spinal or epidural anesthesia 2. Peripheral surgery with general anesthesia or airway surgery with moderate sedation 3. Major surgery or airway surgery with general anesthesia C. Requirement of postoperative opioids. Point score ______ (0–3). 0. None 1. Low-dose oral opioids 2. High-dose oral, parenteral, or neuroaxial opioids
Airway Examination Component
Estimation of perioperative risk is calculated as follows: Overall score = the score for A plus the greater of the score for either B or C. *One point may be subtracted if a patient has been on CPAP or noninvasive positive pressure support (NIPPV) before surgery and will be using his or her appliance consistently during the postoperative period. †One point should be added if a patient with mild or moderate OSAHS also has a resting PaCO2 greater than 50 mm Hg. ‡Patients with a score of 5 or 6 may be at significantly increased perioperative risk from OSAHS. Modified from Gross JB, Bachenberg KL, Benumof JL, et al. American Society of Anesthesiologists Task Force on Perioperative Management: Practice guidelines for the perioperative management of patients with obstructive sleep apnea: a report by the American Society of Anesthesiologists Task Force on perioperative management of patients with obstructive sleep apnea. Anesthesiology 2006;104(5):1081–93, with permission.
given intravenously or epidurally can cause severe airway obstruction and apnea.20,21 Therefore administration of a combination of sedatives and narcotics can be disastrous. Because of the increased incidence of aspiration of gastric contents, an antacid and/or metoclopramide should be given to decrease the gastric acidity and volume. Glycopyrrolate to reduce oral secretions and dexamethasone to reduce airway edema, nausea, and vomiting are generally administered.
2.2 Monitoring In addition to the standard monitors (ECG, noninvasive blood pressure, pulse oximetry, end-tidal carbon dioxide), some patients may require an indwelling arterial catheter. In obese patients, the blood pressure cuff may not fit the upper arm properly and thus may give inaccurate results. In addition, tongue advancement and mandibular osteotomy procedures may require hypotensive anesthesia where accurate blood pressure readings are essential. An indwelling arterial catheter also allows easy access to blood for arterial blood gases and other laboratory testing, intraoperatively and postoperatively. Very rarely, patients with advanced cardiac or pulmonary dysfunction may need a pulmonary artery catheter. For lengthy procedures necessitating an administration of a large
Nonreassuring Findings
Size of the upper teeth Alignment of maxillary and mandibular incisors during normal jaw closure Alignment of maxillary and mandibular incisors during voluntary protrusion of mandible
Long incisors Maxillary incisors anterior to mandibular incisors (overbite) Difficulty bringing mandibular incisors anteriorly to maxillary incisors
Extent of mouth opening (distance between open and lower incisors) Visibility of uvula
Less than 3 cm
Shape of palate Appearance and mobility of the oral structures Thyromental distance Length of neck Thickness of neck Range of motion of the cervical spine
Limited view of the uvula when tongue is protruded with patient in sitting position (Mallampati class III and IV) Highly arched or very narrow Presence of an oral mass, stiffness, lack of resilience Less than three finger breadths (or <6 cm) Short Thick (>60 cm) Diminished flexion or extension of the spine
This table displays some findings of the airway physical examination that may suggest the presence of a difficult intubation. The decision to examine some or all of the airway components shown in this table depends on the clinical context and judgment of the practitioner. The table is not intended as a mandatory or exhaustive list of the components of an airway examination. The order of presentation in this table follows the “line of sight” that occurs during conventional oral laryngoscopy.
quantity of fluids, a Foley catheter should be considered. An assessment of the depth of anesthesia with a bispectral index monitor may facilitate rapid awakening of the patient at the end of the procedure.
2.3 Positioning of the Patient for Surgery Accommodating overweight and obese patients appropriately on the narrow operating table is a common problem. The supine position is the most common position for the OSAHS surgery. In this position the abdominal contents and the diaphragm are pushed into the chest cavity, decreasing the lung volumes and increasing the risk of desaturation. A “ramped” position (Fig. 14.3), in which the upper body, neck, and head are elevated to a point where an imaginary horizontal line can be drawn from the sternal notch to the external ear, may increase the comfort of the patient and improve the laryngeal view during intubation when compared with the “sniffing” position.22
2.4 Preoxygenation of the Patient Maximally preoxygenating obese OSAHS patients is absolutely critical for multiple reasons. Obese patients have impaired
CHAPTER 14 Perioperative and Anesthesia Management
85
chest wall mechanics, such as reduced compliance and functional residual capacity, reduced lung volumes and capacities, have a higher chance of becoming hypoxemic, and might desaturate quicker than nonobese individuals. In addition, these patients may be difficult to ventilate after induction agents and/or paralytics are given, as they can become obstructed very easily due to relaxed redundant soft tissue. Selecting the proper size face mask and maintaining a tight seal around the mask are very important to achieve a maximal inspired oxygen concentration. In normal patients, a minimum of three minutes of tidal volume breathing or eight deep breaths in 1 minute is necessary to sufficiently increase oxygen stores. In the obese OSAHS patient, a longer duration of preoxygenation (at least 5 minutes of tidal volume breathing) is necessary to increase the oxygen stores in the body. Nasopharyngeal or oropharyngeal airways can be indispensable aids for certain patients during the preoxygenation process.
neck, regardless of the Mallampati classification. Familiarity with the ASA practice guidelines for management of the difficult airway,23 particularly the difficult airway algorithm (Fig. 14.4), are mandatory during the induction process for the OSAHS patient. Although succinylcholine seems to be the relaxant of choice for most patients with severe OSAHS, in some cases with an easy, comfortable mask ventilation after intravenous induction, anesthesiologists may elect to give a nondepolarizing relaxant, such as rocuronium, to facilitate the intubation. Succinylcholine is characterized by its rapid onset of action and a relatively rapid recovery, which minimize the risk of desaturating. However, multiple advantages are related to the use of rocuronium. Its slower onset necessitates longer mask ventilation with an inhalational anesthetic (sevoflurane), which can aid in augmenting the relaxation, helping to guarantee amnesia, and raising the arterial oxygen tension (PaO2) even further. A second benefit to the use of rocuronium is the prolonged relaxant effect, avoiding the problem of succinylcholine wearing off quickly, leading to less-thanoptimal relaxation and failed intubation. Relaxation with rocuronium also allows time for the use of the intubating laryngeal mask airway (LMA) or for fiber-optic intubation, if necessary. It is recommended to have multiple laryngoscopes available with different size blades. An Eschmann tube exchanger, sometimes called a gum elastic bougie, or a newer variation of this must also be within reach. An appropriately sized LMA may also prove useful. Attempts at laryngoscopy must be done expeditiously and in a planned, orderly manner. The first attempt can be a longer and a more “exploratory” look around. It is usually the anesthesiologist’s best attempt. If it fails, adjustments are made quickly, which include changing the depth of anesthesia, the dose of muscle relaxant, the head and neck position, the type of laryngoscope blade, the lighting, and the assistant. The anesthesiologist may attempt to optimize the laryngeal view with external manipulations of the larynx and neck. Maneuvers such as BURP (backwards, upwards, rightward pressure) or OLM (optimal laryngeal manipulation) may make the larynx more visible.24 If necessary, the anesthesiologist should call for help from a colleague before a crisis arises. Once the airway is established, maintenance of anesthesia is routine.
3 Intraoperative Care
3.1 Emergence
There is a great level of unpredictability associated with all phases of the perioperative period, particularly with the OSAHS patients. Extra thought, planning, and care are indicated to anticipate possible difficulties, promptly recognize dire situations, and avert any life-threatening complications. Specific questions need to be raised before the intraoperative period. Can the patient be mask ventilated? Is it going to be a difficult intubation? Can the patient’s trachea be intubated with a laryngoscope? Should a GlideScope be available? Experience shows that not all Mallampati grade 1 airways are easily intubated, but also not all Mallampati 3 or 4 airways require an awake or fiber-optic intubation. Nevertheless, it is a good practice to err on the side of caution by anticipating a potentially difficult airway and having a GlideScope available by the operating table whenever taking care of an obese patient with a thick and/or short
Emergence after sleep apnea surgery is perhaps the most critical time for both the anesthesiologist and the patient. Planning and preparation for emergence from anesthesia and tracheal extubation begin before the surgeon approximates completion of the procedure. There are several precautions the anesthesiologist should take before emergence from anesthesia and tracheal extubation because the OSAHS patients have an especially dynamic airway requiring extra support. An oral airway should always be used to prevent obstruction by the tongue. Some surgeons insert nasal trumpets that maintain a patent nasopharynx. An adequate reversal of all muscle relaxants should be ensured, and elevation of the head of the bed might improve the breathing efforts. Support staff might be required to help control what is frequently a slow-to-awaken, agitated, and aggressive postoperative patient.
FIG. 14.3 The “ramped” position, in which the upper body, neck, and head are elevated to a point where an imaginary horizontal line can be drawn from the sternal notch to the external ear, not only improves the comfort of the patient, but also improves the laryngeal view during intubation. Once the endotracheal tube (ETT) is safely secured, some of the blankets can be removed before surgery commences.
86
Section E Anesthesia for OSA/HS
Difficult airway algorithm 1. Assess the likelihood and clinical impact of basic management problems: A. Difficult ventilation B. Difficult intubation C. Difficulty with patient cooperation or consent D. Difficult Tracheostomy 2. Actively pursue opportunities to deliver supplemental oxygen throughout the process of difficult airway management 3. Consider the relative merits and feasibility of basic management choices: A.
Awake intubation
vs
Intubation attempts after induction of general anesthesia
B.
Non-invasive technique for initial approach to intubation
vs
Invasive technique for initial approach to intubation
C.
Preservation of spontaneous ventilation
vs
Ablation of spontaneous ventilation
4. Develop primary and alternative strategies A.
B.
Awake intubation Airway approached by noninvasive intubation
Intubation attempts after induction of general anesthesia Initial intubation attempts successful
Invasive airway access
Initial intubation attempts UNSUCCESSFUL From this point onwards consider: 1. Calling for help 2. Returning to spontaneous ventilation 3. Awakening the patient
FAIL
Succeed
Cancel case
Consider feasibility of other options
Invasive airway access
Face mask ventilation not adequate Face mask ventilation adequate Consider/attempt LMA Nonemergency pathway: Ventilation adequate Intubation unsuccessful
Alternative approaches to intubation Successful intubation
LMA not adequate or not feasible
LMA adequate Emergency pathway: Ventilation not adequate Intubation unsuccessful If both face mask and LMA ventilation become inadequate
Call for help Emergency non-invasive airway ventilation
FAIL after multiple attempts
Successful ventilation
Invasive airway access
Consider feasibility of other options
Awaken patient
FAIL
Emergency invasive airway access
FIG. 14.4 The difficult airway algorithm. (From the American Society of Anesthesiologists Task Force on Management of the Difficult Airway: Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003;98[5]:1269–77, with permission.)
Tracheal extubation should never be rushed in the OSAHS patients. The goal is to awaken the patient with adequate spontaneous ventilation as soon as possible. An evaluation of multiple parameters is mandatory before tracheal extubation. Stable hemodynamic status and adequate pulmonary function should be present, such as adequate tidal volumes
and end-tidal carbon dioxide levels. There should be deliberate and appropriate responses to multiple commands. It is helpful to inform the patient in the preoperative area what they will be asked to do on emergence and to confirm the name that they prefer to be called. The anesthesiologist must also determine the patient’s ability to protect their airway, which
can usually be ensured when the patient has recovered neurologic status sufficiently to follow simple commands (such as opening eyes, squeezing hand) and when the neuromuscular blockade has been reversed adequately. This can be assessed by the use of the peripheral nerve stimulator, but more accurately by a sustained 5-second head lift. Regardless of the technique used, the anesthesiologist looks for the ability of the patient to follow verbal commands repetitively, as the patient may fall back to sleep. Reaching for the endotracheal tube (ETT) is not purposeful movement.25 The more difficult the tracheal intubation, the more patience is needed waiting for tracheal extubation. If the patient fails to satisfy any of these criteria, or if any doubt exists as to the patient’s readiness for the extubation, the anesthesiologist should leave the ETT in place. Once the patient seems ready for extubation, the anesthesiologist should run through another last-moment checklist. Verify that the IV is running and that a sufficient intravenous solution is available. Make sure that succinylcholine is ready if needed, that the suction is still working, and that adequate help is present should any trouble arise. Available airway devices on hand should include a nasopharyngeal airway, a styletted ETT, and a tube exchanging device in case the patient needs to be reintubated. The more difficult patients should probably be extubated over either an Eschmann tube exchange catheter or a ventilating catheter (see Fig. 14.4). Each serves as an introducer to facilitate the potential reinsertion of an ETT, although neither can absolutely guarantee the success of that reinsertion attempt. The Cook catheter has the added advantage of being hollow and having a 15-mm adaptor to allow for ventilation or oxygen insufflation of the lungs, should that be necessary. The extubation procedure begins by moving the patient into a semi-upright position (approximately 45 degrees) to help move the tongue forward and the abdominal contents down and away from the diaphragm. After the airway is suctioned thoroughly, positive pressure is administered. The ETT is removed and 100% oxygen is given immediately via face mask, along with a jaw thrust. If a Cook catheter has been placed, the majority of patients are observed for about 10 minutes and then extubated in the operating room. The worst cases may be transported to the recovery unit with the catheter in place and extubated later when they are fully awake. Some anesthesiologists believe that there is a role for doxapram (0.5–1.0 mg/kg) during emergence to stimulate ventilation and to help speed up awakening. The first minutes after tracheal extubation are crucial, as direct access to the airway has been lost, and postoperative edema and airway closure may ensue. In patients undergoing OSA-corrective surgery, a previously placed nasopharyngeal airway device bypasses the surgical site and decreases the patient’s work of breathing significantly. An oropharyngeal airway is not as well tolerated as a nasal, but may be used if needed. In addition, elevation of the head of the bed after surgery reduces soft tissue edema at the surgical sites and turbinate engorgement, thus improving the nasal airway diameter and airflow. Two immediate concerns after tracheal extubation in the patients with OSAHS are laryngospasm and obstruction secondary tissue edema the presence of blood and other secretions. Although preoperative glycopyrrolate and judicious postoperative suctioning minimize the risk, laryngospasm may still occur. Treatment should include head extension,
CHAPTER 14 Perioperative and Anesthesia Management
87
anterior displacement of the mandible, and positive airway pressure. Intravenous or intramuscular succinylcholine should be readily accessible if required. If these maneuvers fail to stabilize the airway, direct laryngoscopy with tracheal reintubation is necessary, and cricothyrotomy may be performed on rare occasions. Local anesthetics, such as bupivacaine and lidocaine, are frequently used in sleep apnea surgeries, which may lead to unwanted side effects. For example, tongue ablation procedures require the injection of local anesthetic into the tongue base to diminish postoperative pain. However, when the operation is over, patients can experience difficulty with tongue proprioception, leading to feelings of obstruction and possible airway impediment. Therefore minimizing the dose of a local anesthetic, postoperative patient reassurance, and meticulous postoperative airway management are of a great importance.
4 Postoperative Care The main concerns for the anesthesiologist during the postoperative period are the patency of the airway and adequate ventilation and oxygenation. Supplemental oxygen, use of continuous pulse oximetry, supine position, and prompt application of home CPAP must all be implemented into the patient’s care as soon as possible (see Table 14.1).11 Potential edema, bleeding, or opioid-induced airway obstruction/ hypoventilation are the factors that may require monitoring in the ICU. Significant complications generally emerge within the immediate postoperative period. Accordingly, a patient’s status should be evaluated frequently in the postanesthesia care unit (PACU), and the level of postoperative care should be determined accordingly based on the patient’s status. If in doubt, the conservative approach is to admit the patient to a surgical ICU for additional monitoring and management. Airway edema is another major consideration in patients undergoing surgical repair of OSAHS. Small airways compounded with surgical trauma or a difficult intubation put the OSAHS patients at a higher risk for airway compromise. It is of paramount importance for both the anesthesiologist and the surgeon to take all precautions to reducing the airway edema in patients undergoing OSAHS surgery. Adequate monitoring of the hemodynamics is very important in the management of a postoperative OSAHS patient. Hypertension is frequently seen in the OSAHS patients secondary to their heightened sympathetic drive, and it leads to increased bleeding and tissue edema. Therefore blood pressure should be controlled carefully throughout the perioperative period. Postoperative pain management for OSAHS patients must be approached with extreme caution. Ideally, the selected analgesic should have minimal effect on respiratory drive and airway muscle tone while providing strong and adequate pain control. Intraoperatively administered sedatives and narcotics must be considered before providing postoperative analgesia, because of their lingering sedative and depressant effects on the patient. Unfortunately, the spectrum of pharmaceutical options for analgesia ranges from minimal pain relief with a low incidence of side effects to good pain relief with a higher incidence of side effects. OSA patients, who are prone to airway collapse from the redundant tissue, are especially sensitive to the respiratory depressant effects of
88
Section E Anesthesia for OSA/HS
opioid analgesic agents, which may lead to a reduction in the physiologic responses to elevated PaCO2 and decreased PaO2. Both intravenously and intrathecally delivered opioids decrease hypoxic and hypercapneic ventilator responses.26,27 Postoperative oxygen desaturations were 12 to 14 times more common in OSA patients on oral or parenteral narcotic medications compared with nonopioid analgesics.28 Similarly, postoperative epidural morphine in patients with OSA was documented to result in apneas, respiratory depression, and cyanosis.21 Catley et al. reported a high prevalence of disordered breathing combined with severe hypoxemia with oxygen desaturations <80% in surgical patients within 16 hours postoperatively after intravenous morphine, but not after regional anesthesia with the local anesthetic bupivacaine.29 For this reason regional anesthesia may be a more suitable option for the postoperative analgesia in OSA patients. The American Society of Anesthesiologists Task Force on Neuraxial Opioids developed specific practice guidelines to prevent, detect, and manage respiratory depression in patients administered neuraxial opioid analgesia.30 The recommendations include administering single-injection neuraxial opioids in lieu of parenteral opioids; selecting the lowest possible dose of the narcotic medications; cautious coadministration of sedatives, hypnotics, parenteral opioids, or magnesium with neuraxial opioids; careful monitoring of ventilation, oxygenation, and alertness; cautious administration of supplemental oxygen; and availability of reversal agents.30 Special care must also be exercised when administering opioid analgesia to OSA patients on chronic opioid therapy. Case reports of OSA patients on sustained-release opioids for chronic pain management demonstrated prolonged apnea duration, increased severity of hypoxic events, irregular respiratory patterns, and periods of obstructive hypoventilation lasting for 5 or more minutes.31 Because of the aforementioned challenges related to opioid use, alternative analgesic strategies, including nonsteroidal antiinflammatory medications, antiepileptic drugs, and other nonopioid adjuvants, should be considered in this patient population. Patients who failed alternative analgesic regimens and only derive optimal pain control from the narcotic analgesia require prolonged monitoring with capnography and careful titration of the opioid medications. Moreover, an extended PACU observation or full admission might be necessary for this group of patients. Additionally, regardless of prior opioid use, home CPAP should be initiated immediately after extubation or soon after the transfer into the recovery room. The ASA recommends monitoring OSA patients for 3 hours longer than normal patients or for 7 hours after last episode of airway obstruction or desaturation and ensuring that the patients do not desaturate when left undisturbed and that room air saturations are back to baseline.32
References 1. Peppard PE, Young T, Barnet JH, et al. Increased prevalence of sleepdisordered breathing in adults. Am J Epidemiol 2013;177(9):1006–14. 2. Young T, Palta M, Dempsey J, et al. The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med 1993;328(17):1230–5. 3. Carneiro G, Florio RT, Zanella MT, et al. Is mandatory screening for obstructive sleep apnea with polysomnography in all severely obese patients indicated? Sleep Breath 2012;16(1):163–8. 4. Tait AR, Voepel-Lewis T, Burke C, et al. Incidence and risk factors for perioperative adverse respiratory events in children who are obese. Anesthesiology 2008;108(3):375–80.
5. Leiter JC. Upper airway shape: is it important in the pathogenesis of obstructive sleep apnea? Am J Respir Crit Care Med 1996;153(3):894–8. 6. Adesanya AO, Lee W, Greilich NB, et al. Perioperative management of obstructive sleep apnea. Chest 2010;138(6):1489–98. 7. Gupta RM, Parvizi J, Hanssen AD, et al. Postoperative complications in patients with obstructive sleep apnea syndrome undergoing hip or knee replacement: a case-control study. Mayo Clin Proc 2001;76(9): 897–905. 8. Finkel KJ, Searleman AC, Tymkew H, et al. Prevalence of undiagnosed obstructive sleep apnea among adult surgical patients in an academic medical center. Sleep Med 2009;10(7):753–8. 9. Liao P, Yegneswaran B, Vairavanathan S, et al. Postoperative complications in patients with obstructive sleep apnea: a retrospective matched cohort study. Can J Anaesth 2009;56(11):819–28. 10. Memtsoudis S, Liu SS, Ma Y, et al. Perioperative pulmonary outcomes in patients with sleep apnea after noncardiac surgery. Anesth Analg 2011;112(1):113–21. 11. American Society of Anesthesiologists Task Force on Perioperative Management of patients with obstructive sleep apnea. Practice guidelines for the perioperative management of patients with obstructive sleep apnea: an updated report by the American Society of Anesthesiologists Task Force on Perioperative Management of patients with obstructive sleep apnea. Anesthesiology 2014;120(2):268–86. 12. Memtsoudis S, Stundner O, Rasul R, et al. Sleep apnea and total joint arthroplasty under various types of anesthesia. A population-based study of perioperative outcomes. Reg Anesth Pain Med 2013;38(4):274–81. 13. Liu SS, Chisholm MF, John RS, et al. Memtsoudis SG. Risk of postoperative hypoxemia in ambulatory orthopedic surgery patients with diagnosis of obstructive sleep apnea: a retrospective observational study. Patient Saf Surg 2010;4(1):9. 14. Sabers C, Plevak DJ, Schroeder DR, et al. The diagnosis of obstructive sleep apnea as a risk factor for unanticipated admissions in outpatient surgery. Anesth Analg 2003;96(5):1328–35. table of contents. 15. Joshi GP, Ankichetty SP, Gan TJ, et al. Society for Ambulatory Anesthesia consensus statement on preoperative selection of adult patients with obstructive sleep apnea scheduled for ambulatory surgery. Anesth Analg 2012;115(5):1060–8. 16. Selim BJ, Koo BB, Qin L, et al. The Association between nocturnal cardiac arrhythmias and sleep disordered breathing: the DREAM Study. J Clin Sleep Med 2016;12(6):829-37. 17. Somers VK, White DP, Amin R, et al. Sleep apnea and cardiovascular disease: an American Heart Association/American College of Cardiology Foundation Scientific Statement from the American Heart Association Council for High Blood Pressure Research Professional Education Committee, Council on Clinical Cardiology, Stroke Council, and Council on Cardiovascular Nursing. In collaboration with the National Heart, Lung, and Blood Institute National Center on Sleep Disorders Research (National Institutes of Health). Circulation 2008;118(10):1080–111. 18. Brodsky JB, Lemmens HJ, Brock-Utne JG, et al. Morbid obesity and tracheal intubation. Anesth Analg 2002;94(3):732–6. table of contents. 19. Bonora M, St John WM, Bledsoe TA. Differential elevation by protriptyline and depression by diazepam of upper airway respiratory motor activity. Am Rev Respir Dis 1985;131(1):41–5. 20. VanDercar DH, Martinez AP, De Lisser EA. Sleep apnea syndromes: a potential contraindication for patient-controlled analgesia. Anesthesiology 1991;74(3):623–4. 21. Lamarche Y, Martin R, Reiher J, et al. The sleep apnoea syndrome and epidural morphine. Can Anaesth Soc J 1986;33(2):231–3. 22. Collins JS, Lemmens HJ, Brodsky JB, et al. Laryngoscopy and morbid obesity: a comparison of the “sniff ” and “ramped” positions. Obes Surg 2004;14(9):1171–5. 23. American Society of Anesthesiologists Task Force on Management of the Difficult A. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003;98(5):1269–77. 24. Vanner RG, Clarke P, Moore WJ, et al. The effect of cricoid pressure and neck support on the view at laryngoscopy. Anaesthesia 1997; 52(9):896–900. 25. Benumof JL. Obesity, sleep apnea, the airway and anesthesia. Curr Opin Anaesthesiol 2004;17(1):21–30. 26. Weil JV, McCullough RE, Kline JS, et al. Diminished ventilatory response to hypoxia and hypercapnia after morphine in normal man. N Engl J Med 1975;292(21):1103–6.
27. Bailey PL, Lu JK, Pace NL, et al. Effects of intrathecal morphine on the ventilatory response to hypoxia. N Engl J Med 2000;343(17):1228–34. 28. Seet E, Chung F. Obstructive sleep apnea: preoperative assessment. Anesthesiol Clin 2010;28(2):199–215. 29. Catley DM, Thornton C, Jordan C, et al. Pronounced, episodic oxygen desaturation in the postoperative period: its association with ventilatory pattern and analgesic regimen. Anesthesiology 1985;63(1):20–8. 30. American Society of Anesthesiologists Task Force on Neuraxial O, Horlocker TT, Burton AW, et al. Practice guidelines for the prevention,
CHAPTER 14 Perioperative and Anesthesia Management
89
detection, and management of respiratory depression associated with neuraxial opioid administration. Anesthesiology 2009;110(2):218–30. 31. Farney RJ, Walker JM, Cloward TV, et al. Sleep-disordered breathing associated with long-term opioid therapy. Chest 2003;123(2):632–9. 32. Gross JB, Bachenberg KL, Benumof JL, et al. Practice guidelines for the perioperative management of patients with obstructive sleep apnea: a report by the American Society of Anesthesiologists Task Force on Perioperative Management of patients with obstructive sleep apnea. Anesthesiology 2006;104(5):1081–93, quiz 1117–8.
1 Introduction Obstructive sleep apnea/hypopnea syndrome (OSAHS) is a growing health care concern with many potentially detrimental consequences and important anesthetic implications. A rise in obesity among the population of the United States corresponds with an upswing in the prevalence of OSAHS.1 Over the last two decades, the prevalence of OSAHS increased from 26.4% to 33.9% in males and from 13.2% to 17.4% in females.1 An elevation in the body mass index (BMI) of one standard deviation increases the likelihood of coexisting OSAHS by a factor of four.2 In the morbidly obese population, the incidence of obstructive sleep apnea (OSA) is approximately 55% in women and 77% in men.3 Undiagnosed and/or untreated OSA leads to an increased risk of adverse perioperative events, specifically serious pulmonary complications: difficult mask ventilation, difficult direct laryngoscopy or fiber-optic intubations, desaturation and/or airway obstruction, aspiration pneumonia, acute respiratory distress syndrome, or even death.4 The airway obstruction in OSAHS patients results from a decrease in the upper airway muscle tone during sleep; airway narrowing due to the deposition of adipose tissue; and resultant increase in size of pharyngeal structures: the uvula, tonsils, tonsillar pillars, tongue, aryepiglottic folds, and the lateral pharyngeal walls (Fig. 14.1). As a result, the shape of the pharynx changes from a long transverse (lateral) and a short anterior–posterior axis into a narrower ellipsoid with a shorter transverse and a longer anterior–posterior axis. This change in shape impairs the action of the anterior pharyngeal airway dilators: the tensor veli palitini, genioglossus, and hyoid muscles (Fig. 14.2).5 A substantial number of patients seen in the operative units may have undiagnosed and untreated OSAHS. Recent reports have shown that approximately one-quarter of patients undergoing elective surgery have OSAHS, and over 80% of these cases are undiagnosed.6 High prevalence of undiagnosed OSAHS necessitates utmost vigilance, as well as prevention and early recognition of potentially devastating complications. The inability to intubate the patient, respiratory obstruction after tracheal extubation, and severe respiratory depression and respiratory arrest after the administration of sedatives and narcotics are some of the biggest concerns for anesthesiologists. Gupta et al. compared the occurrence of perioperative
complications in OSA (n = 101) and non-OSA patients (n = 101) after a hip or knee replacement and reported 39% and 18% complication rates (hypoxemia, hypercapnia, delirium) in the two groups, respectively.7 These results are corroborated by a number of other large studies, which demonstrate an increased likelihood of perioperative respiratory complications in patients undergoing various types of surgical procedures.8–10 Practice guidelines for the perioperative management of patients with OSAHS published by the American Society of Anesthesiologists (ASA) recommend the use of a scoring system to estimate a risk for perioperative complications from OSAHS, which incorporates three factors: (1) the severity of OSAHS, (2) the invasiveness of the surgery and anesthesia, and (3) the requirement for postoperative opioids (Table 14.1).11 Patients with an overall score of 5 or greater have an increased risk of perioperative complications. The rate of possible complications varies between different types of anesthesia provided. Memtsoudis et al. assessed perioperative outcomes in 30,024 patients diagnosed with OSAHS who underwent an orthopedic surgery between 2006 and 2010 under neuraxial and/or general anesthesia.12 The authors found lower rates of perioperative complications (pulmonary and cardiac and need for blood products) and improved postoperative outcomes (mechanical ventilation, intensive care unit [ICU] admission, length and cost of hospitalization) in patients under neuraxial anesthesia (16.0%) compared with general (17.2%) or combined neuraxial-general anesthesia (18.1%) and concluded that the neuraxial anesthesia may be a more beneficial option for patients with OSA.12 Respiratory compromise can also occur after regional anesthesia as shown by a retrospective study of 206 patients with OSA scheduled for an orthopedic surgery in an outpatient setting, where 34% of the patients experienced hypoxemia postoperatively.13 Despite those results, Sabers et al. demonstrate that presence of OSA does not increase the risk of adverse events or unforeseen hospital admissions in patients undergoing procedures in the outpatient center.14 Thus the Society for Ambulatory Anesthesia concluded that patients diagnosed with OSA can be selected for an outpatient procedure if the following criteria are met: comorbid conditions are managed, patients are able to use their continuous positive airway pressure (CPAP) device postoperatively, and the postprocedural pain can be adequately managed with 81
82
Section E Anesthesia for OSA/HS
Velopharynx or nasopharynx
Tensor palatine
Tensor palatine
Oropharynx
Genio glossus Hyoid muscles
Genio glossus
Velopharynx or nasopharynx Oropharynx
Hyoid muscles Laryngopharynx or hypopharynx
Airspace
Airspace
Laryngopharynx or hypopharynx
B
A
FIG. 14.1 (A) The action of the most important dilator muscles of the upper airway. The tensor palatine, genioglossus, and hyoid muscles enlarge the nasopharynx, oropharynx, and the laryngopharynx, respectively. (B) Collapse of the nasopharynx at the palatal level, the oropharynx at the glottic level, and the laryngopharynx at the epiglottic level. (Modified from Benumof JL: Obstructive sleep apnea in the adult obese patient: implications for airway management. J Clin Anesth 2001;13[2]:144–56, with permission.)
Area (cm2)
A
Anterior
B
Area (cm2)
3.54
4.09
3.00
3.00 Posterior
FIG. 14.2 The effects of a 5-mm change in the anteroposterior (AP) diameter of the airway on airway cross-sectional area is shown for two equally elliptical airways with different lateral/AP ratios. (A) The lateral/AP ratio = 0.5. (B) The lateral/AP ratio = 2. The lateral dimension of each ellipse was held constant. The solid line represents the starting area (3 cm2 in both ellipses), and the dotted line represents the area after a 5-mm increase in the AP diameter. The area change is greater in the ellipse with a more lateral orientation (B). (From Leiter JC: Upper airway shape. Is it important in the pathogenesis of obstructive sleep apnea? Am J Respir Crit Care Med 1996;153:894–8, with permission.)
nonopioid medications.15 After an extensive review of the available scientific literature, the ASA developed specific guidelines and recommendations for the perioperative care of patients diagnosed with OSA (Table 14.2).11
2 Preoperative Assessment of the Patient Whenever possible, the patient should be evaluated in a preoperative clinic several days before the planned surgery. The evaluation should include a review of the current and previous medical records, an interview of the patient, and a physical examination. Frequently, in the event of an emergency procedure or elective surgeries done in the outpatient centers, an evaluation by an anesthesiologist does not take place until immediately before the procedure. This
unfortunately precludes recognition and presurgical management of medical conditions such as sleep apnea. A careful review of all medical records is very important. Reviewing old medical records can be particularly useful with regard to previous anesthetic history, which may reveal airway difficulties, prolonged emergence, an unusual response to anesthetic agents, and the postoperative course. All coexisting medical conditions and treatments should be noted with special focus on the respiratory and cardiovascular organ systems. Any workup that has been done specific to OSAHS (polysomnographic testing, cardiac and pulmonary studies) should be checked, as it may provide valuable information regarding the severity of the disease. Use of CPAP or mouth appliances for the treatment of OSAHS should be investigated, and patients should be encouraged to bring CPAP equipment with them to the hospital on the day of their surgery. A detailed history from the patient and bed partner, if possible, helps in the identification of patients with undiagnosed OSAHS. The patient should be asked about the quality of sleep, frequent awakening, energy level in the morning, and daytime sleepiness and fatigue. The bed partner might offer information related to snoring and apneic episodes during the night. Several tools are available to screen the surgical patients for the presence of OSA: the Berlin Questionnaire, ASA Checklist, and STOPBANG. These tools assess presence of snoring, pauses in breathing, arousals, or choking; daytime somnolence manifested by fatigue or drowsiness despite sufficient sleep; high blood pressure; or specific physical characteristics (BMI >35 kg/m2, neck circumference >17 inches in men and >16 in women, age, gender, structural abnormalities of the orofacial passages). Many OSAHS patients have several coexisting diseases due to hypoxic episodes and obesity. A thorough physical examination is critical with a special focus on the physical characteristics such as body habitus, neck thickness, facial features including presence of a beard, mouth opening, and
CHAPTER 14 Perioperative and Anesthesia Management
83
Table 14.1 Summary of the Recommendations for the Perioperative Care of OSA Patients Developed by the American Society of Anesthesiologists I. Preoperative evaluation
II. Inpatient/ outpatient surgery
III. Preoperative preparation
IV. Postoperative management
V. Criteria for discharge to unmonitored settings Adapted from
Collaboration between anesthesiologists and surgeons is advised to develop a perioperative plan for patients with suspected sleep apnea Preoperative evaluation should include a review of past medical records, interview with the patient and/or family, and physical examination Sleep studies should also be reviewed if available Determination should be made after careful assessment of (1) presence of OSA, (2) anatomic and physiologic derangements, (3) comorbidities, (4) nature of surgery, (5) type of anesthesia, (6) need for postoperative opioids, (7) patient’s age, (8) adequacy of postoperative monitoring, and (9) capabilities of the outpatient center Careful selection of the intraoperative medications to minimize the risk of respiratory compromise Use local anesthetics or peripheral nerve blocks with or without moderate sedation for superficial procedures Continuous monitoring by capnography of the ventilator status in the presence of moderate sedation due to increased risk of airway obstruction Administer CPAP or oral appliance during sedation in patients previously using the devices Secure airway during general anesthesia and deep sedation Use neuraxial anesthesia (spinal/epidural) for peripheral procedures Extubate after a full reversal of the neuromuscular blockade Extubate in the lateral, semi-upright, or other nonsupine position Consider using regional analgesia to avoid using systemic opioids Evaluate risks and benefits of using neuraxial analgesia using opioid only or opioid–local anesthetic mixture versus local anesthetic only Avoid or use with caution continuous background infusions of medication when using patient-controlled analgesia (PCA) with systemic opioids Consider using nonopioid analgesics to reduce the requirement for narcotic medications Exercise caution when combining benzodiazepines and barbiturates, as they increase the risk of respiratory depression Judicious use of supplemental oxygen, as it may also suppress respiratory drive Use CPAP or noninvasive positive pressure ventilation in patients who were using them preoperatively Keep patients in the nonsupine position throughout the recovery process Use continuous pulse oximetry after transfer from the recovery unit into stepdown or telemetry In the event of hypoxemia, frequent, or severe airway obstruction, apply nasal CPAP or noninvasive positive pressure ventilation Postpone discharge until patients are no longer at risk of respiratory compromise Monitor the adequacy of oxygen saturation on room air while patient is sleeping
11
tongue size. The importance of a detailed cardiovascular examination cannot be overemphasized. One should have a low threshold for obtaining an electrocardiogram (ECG) and/or echocardiogram when a suspicion of compromised cardiovascular function arises, and severe cases should be referred to a specialist before an elective surgery. Hypoxic events are associated with several potentially detrimental cardiovascular derangements. For example, patients with moderate to severe OSAHS are nearly three times more likely to have nocturnal cardiac arrhythmias compared with non-OSAHS patients.16 Systemic hypertension is present in 50% of OSAHS patients and is more prevalent with increasing severity of OSAHS.17 Special attention must also be given to the airway of the patient to recognize features predictive of potentially difficult airway management. Frequently, OSA patients have a large tongue and a thick neck, and the probability of a difficult tracheal intubation rises from 5% when the neck circumference is 40 cm to 35% when the neck circumference is 60 cm.18 Moreover, the commonly seen excessive adipose
tissue in the interscapular region (“buffalo hump”) causes misalignment of the oral, pharyngeal, and tracheal axes during direct laryngoscopy. Determining whether tracheal intubation should be performed with the patient awake or under general anesthesia must be individualized on the basis of a methodical, complete airway examination (Table 14.3).
2.1 Premedication Sedatives and narcotics have a propensity to exacerbate the sleep-related apneic episodes and may impair lifesaving arousal in patients with OSAHS. Benzodiazepines and barbiturates preferentially decrease neural input to the upper airway dilating muscles, leading to airway obstruction.19 Anxiolytic drugs such as midazolam should only be administered when close monitoring of the patient by appropriate personnel is possible. This means that the drug should not be given until the patient is about to enter the operating room for surgery. Narcotic medications specifically are associated with a high risk of respiratory depression. Even small doses of narcotics
84
Section E Anesthesia for OSA/HS
Table 14.2 Scoring System for Calculation of Perioperative Risk in Patients With OSAHS‡
Table 14.3 Components of the Preoperative Airway Physical Examination
A. Severity of sleep apnea based on sleep study (or clinical indicators if sleep study not available). Point score ______ (0–3).*† 0. None (AHI = 0–5) 1. Mild (AHI = 6–20) 2. Moderate (AHI = 21–40) 3. Severe (AHI > 40) B. Invasiveness of the surgery and anesthesia. Point score ______ (0–3). 0. Superficial surgery under local or peripheral nerve block without sedation 1. Superficial surgery with moderate sedation or general anesthesia or peripheral surgery with spinal or epidural anesthesia 2. Peripheral surgery with general anesthesia or airway surgery with moderate sedation 3. Major surgery or airway surgery with general anesthesia C. Requirement of postoperative opioids. Point score ______ (0–3). 0. None 1. Low-dose oral opioids 2. High-dose oral, parenteral, or neuroaxial opioids
Airway Examination Component
Estimation of perioperative risk is calculated as follows: Overall score = the score for A plus the greater of the score for either B or C. *One point may be subtracted if a patient has been on CPAP or noninvasive positive pressure support (NIPPV) before surgery and will be using his or her appliance consistently during the postoperative period. †One point should be added if a patient with mild or moderate OSAHS also has a resting PaCO2 greater than 50 mm Hg. ‡Patients with a score of 5 or 6 may be at significantly increased perioperative risk from OSAHS. Modified from Gross JB, Bachenberg KL, Benumof JL, et al. American Society of Anesthesiologists Task Force on Perioperative Management: Practice guidelines for the perioperative management of patients with obstructive sleep apnea: a report by the American Society of Anesthesiologists Task Force on perioperative management of patients with obstructive sleep apnea. Anesthesiology 2006;104(5):1081–93, with permission.
given intravenously or epidurally can cause severe airway obstruction and apnea.20,21 Therefore administration of a combination of sedatives and narcotics can be disastrous. Because of the increased incidence of aspiration of gastric contents, an antacid and/or metoclopramide should be given to decrease the gastric acidity and volume. Glycopyrrolate to reduce oral secretions and dexamethasone to reduce airway edema, nausea, and vomiting are generally administered.
2.2 Monitoring In addition to the standard monitors (ECG, noninvasive blood pressure, pulse oximetry, end-tidal carbon dioxide), some patients may require an indwelling arterial catheter. In obese patients, the blood pressure cuff may not fit the upper arm properly and thus may give inaccurate results. In addition, tongue advancement and mandibular osteotomy procedures may require hypotensive anesthesia where accurate blood pressure readings are essential. An indwelling arterial catheter also allows easy access to blood for arterial blood gases and other laboratory testing, intraoperatively and postoperatively. Very rarely, patients with advanced cardiac or pulmonary dysfunction may need a pulmonary artery catheter. For lengthy procedures necessitating an administration of a large
Nonreassuring Findings
Size of the upper teeth Alignment of maxillary and mandibular incisors during normal jaw closure Alignment of maxillary and mandibular incisors during voluntary protrusion of mandible
Long incisors Maxillary incisors anterior to mandibular incisors (overbite) Difficulty bringing mandibular incisors anteriorly to maxillary incisors
Extent of mouth opening (distance between open and lower incisors) Visibility of uvula
Less than 3 cm
Shape of palate Appearance and mobility of the oral structures Thyromental distance Length of neck Thickness of neck Range of motion of the cervical spine
Limited view of the uvula when tongue is protruded with patient in sitting position (Mallampati class III and IV) Highly arched or very narrow Presence of an oral mass, stiffness, lack of resilience Less than three finger breadths (or <6 cm) Short Thick (>60 cm) Diminished flexion or extension of the spine
This table displays some findings of the airway physical examination that may suggest the presence of a difficult intubation. The decision to examine some or all of the airway components shown in this table depends on the clinical context and judgment of the practitioner. The table is not intended as a mandatory or exhaustive list of the components of an airway examination. The order of presentation in this table follows the “line of sight” that occurs during conventional oral laryngoscopy.
quantity of fluids, a Foley catheter should be considered. An assessment of the depth of anesthesia with a bispectral index monitor may facilitate rapid awakening of the patient at the end of the procedure.
2.3 Positioning of the Patient for Surgery Accommodating overweight and obese patients appropriately on the narrow operating table is a common problem. The supine position is the most common position for the OSAHS surgery. In this position the abdominal contents and the diaphragm are pushed into the chest cavity, decreasing the lung volumes and increasing the risk of desaturation. A “ramped” position (Fig. 14.3), in which the upper body, neck, and head are elevated to a point where an imaginary horizontal line can be drawn from the sternal notch to the external ear, may increase the comfort of the patient and improve the laryngeal view during intubation when compared with the “sniffing” position.22
2.4 Preoxygenation of the Patient Maximally preoxygenating obese OSAHS patients is absolutely critical for multiple reasons. Obese patients have impaired
CHAPTER 14 Perioperative and Anesthesia Management
85
chest wall mechanics, such as reduced compliance and functional residual capacity, reduced lung volumes and capacities, have a higher chance of becoming hypoxemic, and might desaturate quicker than nonobese individuals. In addition, these patients may be difficult to ventilate after induction agents and/or paralytics are given, as they can become obstructed very easily due to relaxed redundant soft tissue. Selecting the proper size face mask and maintaining a tight seal around the mask are very important to achieve a maximal inspired oxygen concentration. In normal patients, a minimum of three minutes of tidal volume breathing or eight deep breaths in 1 minute is necessary to sufficiently increase oxygen stores. In the obese OSAHS patient, a longer duration of preoxygenation (at least 5 minutes of tidal volume breathing) is necessary to increase the oxygen stores in the body. Nasopharyngeal or oropharyngeal airways can be indispensable aids for certain patients during the preoxygenation process.
neck, regardless of the Mallampati classification. Familiarity with the ASA practice guidelines for management of the difficult airway,23 particularly the difficult airway algorithm (Fig. 14.4), are mandatory during the induction process for the OSAHS patient. Although succinylcholine seems to be the relaxant of choice for most patients with severe OSAHS, in some cases with an easy, comfortable mask ventilation after intravenous induction, anesthesiologists may elect to give a nondepolarizing relaxant, such as rocuronium, to facilitate the intubation. Succinylcholine is characterized by its rapid onset of action and a relatively rapid recovery, which minimize the risk of desaturating. However, multiple advantages are related to the use of rocuronium. Its slower onset necessitates longer mask ventilation with an inhalational anesthetic (sevoflurane), which can aid in augmenting the relaxation, helping to guarantee amnesia, and raising the arterial oxygen tension (PaO2) even further. A second benefit to the use of rocuronium is the prolonged relaxant effect, avoiding the problem of succinylcholine wearing off quickly, leading to less-thanoptimal relaxation and failed intubation. Relaxation with rocuronium also allows time for the use of the intubating laryngeal mask airway (LMA) or for fiber-optic intubation, if necessary. It is recommended to have multiple laryngoscopes available with different size blades. An Eschmann tube exchanger, sometimes called a gum elastic bougie, or a newer variation of this must also be within reach. An appropriately sized LMA may also prove useful. Attempts at laryngoscopy must be done expeditiously and in a planned, orderly manner. The first attempt can be a longer and a more “exploratory” look around. It is usually the anesthesiologist’s best attempt. If it fails, adjustments are made quickly, which include changing the depth of anesthesia, the dose of muscle relaxant, the head and neck position, the type of laryngoscope blade, the lighting, and the assistant. The anesthesiologist may attempt to optimize the laryngeal view with external manipulations of the larynx and neck. Maneuvers such as BURP (backwards, upwards, rightward pressure) or OLM (optimal laryngeal manipulation) may make the larynx more visible.24 If necessary, the anesthesiologist should call for help from a colleague before a crisis arises. Once the airway is established, maintenance of anesthesia is routine.
3 Intraoperative Care
3.1 Emergence
There is a great level of unpredictability associated with all phases of the perioperative period, particularly with the OSAHS patients. Extra thought, planning, and care are indicated to anticipate possible difficulties, promptly recognize dire situations, and avert any life-threatening complications. Specific questions need to be raised before the intraoperative period. Can the patient be mask ventilated? Is it going to be a difficult intubation? Can the patient’s trachea be intubated with a laryngoscope? Should a GlideScope be available? Experience shows that not all Mallampati grade 1 airways are easily intubated, but also not all Mallampati 3 or 4 airways require an awake or fiber-optic intubation. Nevertheless, it is a good practice to err on the side of caution by anticipating a potentially difficult airway and having a GlideScope available by the operating table whenever taking care of an obese patient with a thick and/or short
Emergence after sleep apnea surgery is perhaps the most critical time for both the anesthesiologist and the patient. Planning and preparation for emergence from anesthesia and tracheal extubation begin before the surgeon approximates completion of the procedure. There are several precautions the anesthesiologist should take before emergence from anesthesia and tracheal extubation because the OSAHS patients have an especially dynamic airway requiring extra support. An oral airway should always be used to prevent obstruction by the tongue. Some surgeons insert nasal trumpets that maintain a patent nasopharynx. An adequate reversal of all muscle relaxants should be ensured, and elevation of the head of the bed might improve the breathing efforts. Support staff might be required to help control what is frequently a slow-to-awaken, agitated, and aggressive postoperative patient.
FIG. 14.3 The “ramped” position, in which the upper body, neck, and head are elevated to a point where an imaginary horizontal line can be drawn from the sternal notch to the external ear, not only improves the comfort of the patient, but also improves the laryngeal view during intubation. Once the endotracheal tube (ETT) is safely secured, some of the blankets can be removed before surgery commences.
86
Section E Anesthesia for OSA/HS
Difficult airway algorithm 1. Assess the likelihood and clinical impact of basic management problems: A. Difficult ventilation B. Difficult intubation C. Difficulty with patient cooperation or consent D. Difficult Tracheostomy 2. Actively pursue opportunities to deliver supplemental oxygen throughout the process of difficult airway management 3. Consider the relative merits and feasibility of basic management choices: A.
Awake intubation
vs
Intubation attempts after induction of general anesthesia
B.
Non-invasive technique for initial approach to intubation
vs
Invasive technique for initial approach to intubation
C.
Preservation of spontaneous ventilation
vs
Ablation of spontaneous ventilation
4. Develop primary and alternative strategies A.
B.
Awake intubation Airway approached by noninvasive intubation
Intubation attempts after induction of general anesthesia Initial intubation attempts successful
Invasive airway access
Initial intubation attempts UNSUCCESSFUL From this point onwards consider: 1. Calling for help 2. Returning to spontaneous ventilation 3. Awakening the patient
FAIL
Succeed
Cancel case
Consider feasibility of other options
Invasive airway access
Face mask ventilation not adequate Face mask ventilation adequate Consider/attempt LMA Nonemergency pathway: Ventilation adequate Intubation unsuccessful
Alternative approaches to intubation Successful intubation
LMA not adequate or not feasible
LMA adequate Emergency pathway: Ventilation not adequate Intubation unsuccessful If both face mask and LMA ventilation become inadequate
Call for help Emergency non-invasive airway ventilation
FAIL after multiple attempts
Successful ventilation
Invasive airway access
Consider feasibility of other options
Awaken patient
FAIL
Emergency invasive airway access
FIG. 14.4 The difficult airway algorithm. (From the American Society of Anesthesiologists Task Force on Management of the Difficult Airway: Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003;98[5]:1269–77, with permission.)
Tracheal extubation should never be rushed in the OSAHS patients. The goal is to awaken the patient with adequate spontaneous ventilation as soon as possible. An evaluation of multiple parameters is mandatory before tracheal extubation. Stable hemodynamic status and adequate pulmonary function should be present, such as adequate tidal volumes
and end-tidal carbon dioxide levels. There should be deliberate and appropriate responses to multiple commands. It is helpful to inform the patient in the preoperative area what they will be asked to do on emergence and to confirm the name that they prefer to be called. The anesthesiologist must also determine the patient’s ability to protect their airway, which
can usually be ensured when the patient has recovered neurologic status sufficiently to follow simple commands (such as opening eyes, squeezing hand) and when the neuromuscular blockade has been reversed adequately. This can be assessed by the use of the peripheral nerve stimulator, but more accurately by a sustained 5-second head lift. Regardless of the technique used, the anesthesiologist looks for the ability of the patient to follow verbal commands repetitively, as the patient may fall back to sleep. Reaching for the endotracheal tube (ETT) is not purposeful movement.25 The more difficult the tracheal intubation, the more patience is needed waiting for tracheal extubation. If the patient fails to satisfy any of these criteria, or if any doubt exists as to the patient’s readiness for the extubation, the anesthesiologist should leave the ETT in place. Once the patient seems ready for extubation, the anesthesiologist should run through another last-moment checklist. Verify that the IV is running and that a sufficient intravenous solution is available. Make sure that succinylcholine is ready if needed, that the suction is still working, and that adequate help is present should any trouble arise. Available airway devices on hand should include a nasopharyngeal airway, a styletted ETT, and a tube exchanging device in case the patient needs to be reintubated. The more difficult patients should probably be extubated over either an Eschmann tube exchange catheter or a ventilating catheter (see Fig. 14.4). Each serves as an introducer to facilitate the potential reinsertion of an ETT, although neither can absolutely guarantee the success of that reinsertion attempt. The Cook catheter has the added advantage of being hollow and having a 15-mm adaptor to allow for ventilation or oxygen insufflation of the lungs, should that be necessary. The extubation procedure begins by moving the patient into a semi-upright position (approximately 45 degrees) to help move the tongue forward and the abdominal contents down and away from the diaphragm. After the airway is suctioned thoroughly, positive pressure is administered. The ETT is removed and 100% oxygen is given immediately via face mask, along with a jaw thrust. If a Cook catheter has been placed, the majority of patients are observed for about 10 minutes and then extubated in the operating room. The worst cases may be transported to the recovery unit with the catheter in place and extubated later when they are fully awake. Some anesthesiologists believe that there is a role for doxapram (0.5–1.0 mg/kg) during emergence to stimulate ventilation and to help speed up awakening. The first minutes after tracheal extubation are crucial, as direct access to the airway has been lost, and postoperative edema and airway closure may ensue. In patients undergoing OSA-corrective surgery, a previously placed nasopharyngeal airway device bypasses the surgical site and decreases the patient’s work of breathing significantly. An oropharyngeal airway is not as well tolerated as a nasal, but may be used if needed. In addition, elevation of the head of the bed after surgery reduces soft tissue edema at the surgical sites and turbinate engorgement, thus improving the nasal airway diameter and airflow. Two immediate concerns after tracheal extubation in the patients with OSAHS are laryngospasm and obstruction secondary tissue edema the presence of blood and other secretions. Although preoperative glycopyrrolate and judicious postoperative suctioning minimize the risk, laryngospasm may still occur. Treatment should include head extension,
CHAPTER 14 Perioperative and Anesthesia Management
87
anterior displacement of the mandible, and positive airway pressure. Intravenous or intramuscular succinylcholine should be readily accessible if required. If these maneuvers fail to stabilize the airway, direct laryngoscopy with tracheal reintubation is necessary, and cricothyrotomy may be performed on rare occasions. Local anesthetics, such as bupivacaine and lidocaine, are frequently used in sleep apnea surgeries, which may lead to unwanted side effects. For example, tongue ablation procedures require the injection of local anesthetic into the tongue base to diminish postoperative pain. However, when the operation is over, patients can experience difficulty with tongue proprioception, leading to feelings of obstruction and possible airway impediment. Therefore minimizing the dose of a local anesthetic, postoperative patient reassurance, and meticulous postoperative airway management are of a great importance.
4 Postoperative Care The main concerns for the anesthesiologist during the postoperative period are the patency of the airway and adequate ventilation and oxygenation. Supplemental oxygen, use of continuous pulse oximetry, supine position, and prompt application of home CPAP must all be implemented into the patient’s care as soon as possible (see Table 14.1).11 Potential edema, bleeding, or opioid-induced airway obstruction/ hypoventilation are the factors that may require monitoring in the ICU. Significant complications generally emerge within the immediate postoperative period. Accordingly, a patient’s status should be evaluated frequently in the postanesthesia care unit (PACU), and the level of postoperative care should be determined accordingly based on the patient’s status. If in doubt, the conservative approach is to admit the patient to a surgical ICU for additional monitoring and management. Airway edema is another major consideration in patients undergoing surgical repair of OSAHS. Small airways compounded with surgical trauma or a difficult intubation put the OSAHS patients at a higher risk for airway compromise. It is of paramount importance for both the anesthesiologist and the surgeon to take all precautions to reducing the airway edema in patients undergoing OSAHS surgery. Adequate monitoring of the hemodynamics is very important in the management of a postoperative OSAHS patient. Hypertension is frequently seen in the OSAHS patients secondary to their heightened sympathetic drive, and it leads to increased bleeding and tissue edema. Therefore blood pressure should be controlled carefully throughout the perioperative period. Postoperative pain management for OSAHS patients must be approached with extreme caution. Ideally, the selected analgesic should have minimal effect on respiratory drive and airway muscle tone while providing strong and adequate pain control. Intraoperatively administered sedatives and narcotics must be considered before providing postoperative analgesia, because of their lingering sedative and depressant effects on the patient. Unfortunately, the spectrum of pharmaceutical options for analgesia ranges from minimal pain relief with a low incidence of side effects to good pain relief with a higher incidence of side effects. OSA patients, who are prone to airway collapse from the redundant tissue, are especially sensitive to the respiratory depressant effects of
88
Section E Anesthesia for OSA/HS
opioid analgesic agents, which may lead to a reduction in the physiologic responses to elevated PaCO2 and decreased PaO2. Both intravenously and intrathecally delivered opioids decrease hypoxic and hypercapneic ventilator responses.26,27 Postoperative oxygen desaturations were 12 to 14 times more common in OSA patients on oral or parenteral narcotic medications compared with nonopioid analgesics.28 Similarly, postoperative epidural morphine in patients with OSA was documented to result in apneas, respiratory depression, and cyanosis.21 Catley et al. reported a high prevalence of disordered breathing combined with severe hypoxemia with oxygen desaturations <80% in surgical patients within 16 hours postoperatively after intravenous morphine, but not after regional anesthesia with the local anesthetic bupivacaine.29 For this reason regional anesthesia may be a more suitable option for the postoperative analgesia in OSA patients. The American Society of Anesthesiologists Task Force on Neuraxial Opioids developed specific practice guidelines to prevent, detect, and manage respiratory depression in patients administered neuraxial opioid analgesia.30 The recommendations include administering single-injection neuraxial opioids in lieu of parenteral opioids; selecting the lowest possible dose of the narcotic medications; cautious coadministration of sedatives, hypnotics, parenteral opioids, or magnesium with neuraxial opioids; careful monitoring of ventilation, oxygenation, and alertness; cautious administration of supplemental oxygen; and availability of reversal agents.30 Special care must also be exercised when administering opioid analgesia to OSA patients on chronic opioid therapy. Case reports of OSA patients on sustained-release opioids for chronic pain management demonstrated prolonged apnea duration, increased severity of hypoxic events, irregular respiratory patterns, and periods of obstructive hypoventilation lasting for 5 or more minutes.31 Because of the aforementioned challenges related to opioid use, alternative analgesic strategies, including nonsteroidal antiinflammatory medications, antiepileptic drugs, and other nonopioid adjuvants, should be considered in this patient population. Patients who failed alternative analgesic regimens and only derive optimal pain control from the narcotic analgesia require prolonged monitoring with capnography and careful titration of the opioid medications. Moreover, an extended PACU observation or full admission might be necessary for this group of patients. Additionally, regardless of prior opioid use, home CPAP should be initiated immediately after extubation or soon after the transfer into the recovery room. The ASA recommends monitoring OSA patients for 3 hours longer than normal patients or for 7 hours after last episode of airway obstruction or desaturation and ensuring that the patients do not desaturate when left undisturbed and that room air saturations are back to baseline.32
References 1. Peppard PE, Young T, Barnet JH, et al. Increased prevalence of sleepdisordered breathing in adults. Am J Epidemiol 2013;177(9):1006–14. 2. Young T, Palta M, Dempsey J, et al. The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med 1993;328(17):1230–5. 3. Carneiro G, Florio RT, Zanella MT, et al. Is mandatory screening for obstructive sleep apnea with polysomnography in all severely obese patients indicated? Sleep Breath 2012;16(1):163–8. 4. Tait AR, Voepel-Lewis T, Burke C, et al. Incidence and risk factors for perioperative adverse respiratory events in children who are obese. Anesthesiology 2008;108(3):375–80.
5. Leiter JC. Upper airway shape: is it important in the pathogenesis of obstructive sleep apnea? Am J Respir Crit Care Med 1996;153(3):894–8. 6. Adesanya AO, Lee W, Greilich NB, et al. Perioperative management of obstructive sleep apnea. Chest 2010;138(6):1489–98. 7. Gupta RM, Parvizi J, Hanssen AD, et al. Postoperative complications in patients with obstructive sleep apnea syndrome undergoing hip or knee replacement: a case-control study. Mayo Clin Proc 2001;76(9): 897–905. 8. Finkel KJ, Searleman AC, Tymkew H, et al. Prevalence of undiagnosed obstructive sleep apnea among adult surgical patients in an academic medical center. Sleep Med 2009;10(7):753–8. 9. Liao P, Yegneswaran B, Vairavanathan S, et al. Postoperative complications in patients with obstructive sleep apnea: a retrospective matched cohort study. Can J Anaesth 2009;56(11):819–28. 10. Memtsoudis S, Liu SS, Ma Y, et al. Perioperative pulmonary outcomes in patients with sleep apnea after noncardiac surgery. Anesth Analg 2011;112(1):113–21. 11. American Society of Anesthesiologists Task Force on Perioperative Management of patients with obstructive sleep apnea. Practice guidelines for the perioperative management of patients with obstructive sleep apnea: an updated report by the American Society of Anesthesiologists Task Force on Perioperative Management of patients with obstructive sleep apnea. Anesthesiology 2014;120(2):268–86. 12. Memtsoudis S, Stundner O, Rasul R, et al. Sleep apnea and total joint arthroplasty under various types of anesthesia. A population-based study of perioperative outcomes. Reg Anesth Pain Med 2013;38(4):274–81. 13. Liu SS, Chisholm MF, John RS, et al. Memtsoudis SG. Risk of postoperative hypoxemia in ambulatory orthopedic surgery patients with diagnosis of obstructive sleep apnea: a retrospective observational study. Patient Saf Surg 2010;4(1):9. 14. Sabers C, Plevak DJ, Schroeder DR, et al. The diagnosis of obstructive sleep apnea as a risk factor for unanticipated admissions in outpatient surgery. Anesth Analg 2003;96(5):1328–35. table of contents. 15. Joshi GP, Ankichetty SP, Gan TJ, et al. Society for Ambulatory Anesthesia consensus statement on preoperative selection of adult patients with obstructive sleep apnea scheduled for ambulatory surgery. Anesth Analg 2012;115(5):1060–8. 16. Selim BJ, Koo BB, Qin L, et al. The Association between nocturnal cardiac arrhythmias and sleep disordered breathing: the DREAM Study. J Clin Sleep Med 2016;12(6):829-37. 17. Somers VK, White DP, Amin R, et al. Sleep apnea and cardiovascular disease: an American Heart Association/American College of Cardiology Foundation Scientific Statement from the American Heart Association Council for High Blood Pressure Research Professional Education Committee, Council on Clinical Cardiology, Stroke Council, and Council on Cardiovascular Nursing. In collaboration with the National Heart, Lung, and Blood Institute National Center on Sleep Disorders Research (National Institutes of Health). Circulation 2008;118(10):1080–111. 18. Brodsky JB, Lemmens HJ, Brock-Utne JG, et al. Morbid obesity and tracheal intubation. Anesth Analg 2002;94(3):732–6. table of contents. 19. Bonora M, St John WM, Bledsoe TA. Differential elevation by protriptyline and depression by diazepam of upper airway respiratory motor activity. Am Rev Respir Dis 1985;131(1):41–5. 20. VanDercar DH, Martinez AP, De Lisser EA. Sleep apnea syndromes: a potential contraindication for patient-controlled analgesia. Anesthesiology 1991;74(3):623–4. 21. Lamarche Y, Martin R, Reiher J, et al. The sleep apnoea syndrome and epidural morphine. Can Anaesth Soc J 1986;33(2):231–3. 22. Collins JS, Lemmens HJ, Brodsky JB, et al. Laryngoscopy and morbid obesity: a comparison of the “sniff ” and “ramped” positions. Obes Surg 2004;14(9):1171–5. 23. American Society of Anesthesiologists Task Force on Management of the Difficult A. Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003;98(5):1269–77. 24. Vanner RG, Clarke P, Moore WJ, et al. The effect of cricoid pressure and neck support on the view at laryngoscopy. Anaesthesia 1997; 52(9):896–900. 25. Benumof JL. Obesity, sleep apnea, the airway and anesthesia. Curr Opin Anaesthesiol 2004;17(1):21–30. 26. Weil JV, McCullough RE, Kline JS, et al. Diminished ventilatory response to hypoxia and hypercapnia after morphine in normal man. N Engl J Med 1975;292(21):1103–6.
27. Bailey PL, Lu JK, Pace NL, et al. Effects of intrathecal morphine on the ventilatory response to hypoxia. N Engl J Med 2000;343(17):1228–34. 28. Seet E, Chung F. Obstructive sleep apnea: preoperative assessment. Anesthesiol Clin 2010;28(2):199–215. 29. Catley DM, Thornton C, Jordan C, et al. Pronounced, episodic oxygen desaturation in the postoperative period: its association with ventilatory pattern and analgesic regimen. Anesthesiology 1985;63(1):20–8. 30. American Society of Anesthesiologists Task Force on Neuraxial O, Horlocker TT, Burton AW, et al. Practice guidelines for the prevention,
CHAPTER 14 Perioperative and Anesthesia Management
89
detection, and management of respiratory depression associated with neuraxial opioid administration. Anesthesiology 2009;110(2):218–30. 31. Farney RJ, Walker JM, Cloward TV, et al. Sleep-disordered breathing associated with long-term opioid therapy. Chest 2003;123(2):632–9. 32. Gross JB, Bachenberg KL, Benumof JL, et al. Practice guidelines for the perioperative management of patients with obstructive sleep apnea: a report by the American Society of Anesthesiologists Task Force on Perioperative Management of patients with obstructive sleep apnea. Anesthesiology 2006;104(5):1081–93, quiz 1117–8.