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Air medical rapid sequence intubation: How can we achieve success?
Air Medical Rapid Sequence Intubation: How Can We Achieve Success? Eric R. Swanson, MD, David E. Fosnocht, MD, and Erik D. Barton, MD, MS
ABSTRACT Airway management is an essential component of the air medical transport of critically ill or injured patients. Many controversies surround the use of rapid sequence intubation (RSI) in the prehospital setting. The challenges of establishing an airway in this environment may exceed those in the hospital. However, it is clear that the same high standards for success demanded in the hospital must be applied to RSI in the prehospital setting for the practice to be accepted and result in positive outcomes. Given their volume of high acuity patients, air medical providers are ideal candidates for performing prehospital RSI. Undertaking this responsibility requires commitment to training and quality improvement. We present the components required to establish and maintain a successful air medical RSI program.
Introduction Airway management is an essential component of the air medical transport of critically ill or injured patients. Indeed, obtaining an airway is one of the fundamental skills of air medical prehospital providers.1,2 Challenges to intubation in the prehospital setting include nonfasted, awake, or combative patients with intact airway reflexes making intubation difficult or impossible. For this reason, prehospital airway management has been reported with highly variable success rates in a variety of emergency medical services (EMS) settings. Rapid sequence intubation (RSI) is defined as the use of a sedative/induction agent and a neuromuscular blocking agent to facilitate intubation. The potential advantages of RSI include fewer intubation attempts, fewer complications, increased overall success rate, and decreased physiologic stress to the patient. RSI has emerged as the preferred method for airway management in the air medical setting.2-11 A recent survey of 196 air medical programs found that, of the 114 respondents, 93% of the programs used RSI.12 Several recent articles have highlighted controversies regarding the use of prehospital intubation and RSI. Gausche et al13 reported that the addition of out-of-hospital endotracheal intubation to a paramedic scope of practice that already includes bag/valve/mask ventilation (BVM) did not improve survival or neurological outcome of pediatric patients treated in an urban EMS system. The initial results of the San Diego Paramedic RSI trial reported an intubation success rate of only 40
84.2% in patients with severe head injury undergoing RSI.14 An accompanying editorial points out that that RSI should enable prehospital providers to achieve successful intubation rates similar to those seen in the hospital. They say the 15% failure rate in the San Diego trial did not meet the in-hospital expectation that RSI should “never or rarely fail.”15 The controversy over prehospital intubation and RSI is not limited to ground EMS programs. In 2002 Mizelle et al16 presented 3 cases of preventable morbidity and mortality from prehospital paralytic-assisted intubation in the air medical setting. Recently, 2 outcome studies have reported increased morbidity and mortality in patients with head injury undergoing prehospital intubation compared with in-hospital intubation.17,18 One of these was from the San Diego Paramedic RSI trial, and the results prompted suspension of the trial and discontinuation of their RSI protocol.18 Given the recent controversy over prehospital intubation and RSI, the following questions remain: What is the role of air medical programs in providing prehospital airway management? Can prehospital air medical RSI success rates approach those of in-hospital rates? Does air medical RSI improve patient outcome? In an attempt to address these questions, we present the components required to establish and maintain a successful air medical prehospital RSI program.
Goals for a Successful Prehospital RSI Program Prehospital RSI success rates should be comparable with in-hospital rates. The challenges of establishing an airway in the prehospital
Division of Emergency Medicine and AirMed, University of Utah Health Sciences Center, Salt Lake City Address for correspondence: Eric R. Swanson, MD, Division of Emergency Medicine, 1150 Moran Bldg., 175 N. Medical Dr., Salt Lake City, UT 84132; [email protected] 1067-991X/$30.00 Copyright 2005 by Air Medical Journal Associates doi:10.1016/j.amj.2004.10.008
Air Medical Journal 24:1
setting may exceed those seen in the hospital arena. However, it is clear that the same high standards for success must be applied to RSI in the prehospital setting for the practice to be accepted and achieve the improved outcomes seen in other settings. The training of prehospital providers needs to have the same standards and scrutiny of practice as seen in the hospital setting. Medical director involvement and quality-improvement programs to monitor ongoing success are essential.
Table 1
Multiple intubation attempts must be limited.
4. Standardized RSI protocols
Preliminary work suggests that multiple intubation attempts are associated with an increased risk of field death.19 Early recognition of a difficult or failed airway will limit further futile attempts at intubation. Backup or rescue devices must be available and used immediately on recognition of a failed airway in a preplanned, systemwide approach.
5. Backup rescue airway methods
Misplaced endotracheal tubes must be avoided. Several studies have reported the incidence of misplaced endotracheal (ET) tubes to be unacceptably high with prehospital intubation.20,21 Misplaced or dislodged ET tubes have been associated with an increased risk of field or emergencydepartment (ED) death.19 The depth of the ET tube should be noted and “objective” measures [end-tidal CO2 (ETCO2) detection and/or aspiration devices] should be used on every prehospital intubation. Continuous vigilance and monitoring of ET tube placement must be maintained.
Patients must be closely monitored, and hyperventilation, hypoxia, and hypotension must be avoided. Recent reports from the San Diego investigators are shedding some light on the potential reasons for the observed increase in morbidity and mortality associated with prehospital RSI in patients with traumatic brain injury. Dunford et al22 reported a concerning incidence of oxygen desaturation (57%) and bradycardia (19%) in a subset of patients undergoing prehospital RSI. Davis et al23 found that air medical transport of paramedic RSI patients is associated with improved outcomes, suggesting that air medical crews may provide superior postintubation management compared with their ground counterparts.
Steps Toward Improving Prehospital RSI Success Several components of an RSI program must be in place to achieve the goals outlined above. In a position paper on prehospital RSI, the National Association of EMS Physicians (NAEMSP)24 identified 6 minimum elements necessary for a prehospital RSI program (Table 1). Air medical transport programs should incorporate these minimum elements into their RSI programs. The first element listed is medical direction and supervision. This aspect is the most crucial of a prehospital RSI program, and all of the other elements are more likely to be achieved in the presence of a motivated and involved medical director. Improving prehospital RSI success requires programs to improve intubation technique, institute training and quality improvement for intubation and RSI, select appropriate methods for airway management, have a planned stepwise January-February 2005
NAEMSP MINIMUM ELEMENTS FOR PREHOSPITAL RAPID SEQUENCE INTUBATION PROGRAMS 1. Medical direction and supervision 2. Training and continuing education 3. Resources for patient monitoring, drug storage and delivery, confirmation and monitoring of ET tube placement
6. Continuing quality assurance and performance review
approach to RSI, have adequate backup methods for failed RSI, and have procedures in place to confirm ET tube placement and ongoing patient monitoring.
Improving Intubation Technique Personnel who perform RSI should have substantial intubation experience. Even experienced providers may have had little formal laryngoscopy training, and the first step to any prehospital RSI program should be to establish a foundation of basic airway management and laryngoscopy skills. Techniques have been described that can improve glottic visualization and intubation success. Cricoid pressure (a necessary component of RSI) may worsen glottic visualization. The BURP (backward, upward, rightward pressure) maneuver was designed to improve glottic visualization but requires a second operator who is blinded to what that intubator sees.25 External laryngeal manipulation (ELM) or bimanual intubation consists of the intubator using his or her free right hand to manipulate the larynx to obtain the best visualization of the glottic opening. Once the best view has been obtained, a second operator holds the larynx in the ideal position. ELM has been shown to improve laryngeal view during intubation.26,27 Knopp28 has stated that ELM is a technique that emergency physicians should incorporate into their practice as one of the essential skills for tracheal intubation. We agree with this statement and believe that all air medical personnel performing intubation should be familiar with this technique. The shape of the ET tube stylet also may have an effect on visualization of the glottic opening and ability to maneuver the tip of the ET tube. Preliminary work suggests that a stylet shape that is straight to the balloon, then angled at 30 to 40 degrees, compared with a gentle curve, permits better glottic and ET tube tip visualization and improves maneuverability within the hypopharynx.29
Training and Quality Improvement for Intubation and RSI No standard training curriculum exists for air medical RSI, although several studies have described training regimens for implementing RSI programs. Training was varied, with several programs using operating-room time for initial or ongoing training.4,6,9,11,30 Cadaver, manikin, and animal models have 41
Table 2 BASIC PREMISES OF RAPID SEQUENCE INTUBATION 1. All patients are assumed to have a full stomach. 2. Interposed ventilations should be avoided whenever possible to prevent gastric filling before intubation. 3. Use of both an induction (sedative) agent and paralytic maximizes visualization and completely controls the patient. 4. Induction doses are meant to cause unconscious sedation and are typically 2 to 3 times higher than those used in “conscious” sedation. 5. Cricoid pressure should be used to prevent passive regurgitation.
been used for airway skills laboratories.2,4,10,11 Several studies described an ongoing requirement to perform a certain number of intubations during a defined period.2,4,10,11,31 Training in prehospital RSI is necessarily variable, reflecting skills, environments, and requirements encountered in different systems. The skill of airway management has been shown to decline after initial training, but independent practice and periodic observation with feedback have been shown to be effective in maintaining performance.32 We previously described the effect of an airway education program consisting of initial orientation, continuing education, and quality improvement on prehospital intubation in an air medical service already using RSI.11 That study demonstrated an increase in the use of RSI, a dramatic decrease in the use of neuromuscular blockade without sedation, and a decrease in cricothyrotomy rate after the institution of an airway education program. This program has shown success rates of 98% to 100% with prehospital RSI in the air medical setting.33,34 One of the difficulties in performing quality improvement and research with prehospital intubation is the lack of uniform definitions, terminology, and reporting formats. Recently the National Association of EMS Physicians issued a position paper recommending guidelines for uniform reporting of data from out-of-hospital airway management.35 The paper recommends that all EMS systems monitor the quality of outof-hospital airway management procedures. A template of the uniform airway management data form may be obtained from the group’s Web site (www.naemsp.org). At a minimum, the quality-improvement process should involve a systemwide review of all airway management encounters and a detailed educational dissection of any difficult or failed airway incidents.
Selecting Appropriate Methods for Airway Management Using RSI provides the fastest and most effective way of obtaining a definitive airway. Some patients are unable to be intubated by the oral route during RSI, putting them at considerable risk because they no longer have spontaneous ventilation. The failed intubation rate in the anesthesia literature is 0.1 to 0.4% and around 1% in the ED setting. This number 42
may be higher in the prehospital setting, where conditions are not controlled. The ideal situation would be to identify all patients in whom intubation will fail before administering RSI medications. Unfortunately, many of the methods and screening tests available for detecting the difficult airway have been shown to have limited use in ED patients undergoing intubation. 36 In the case of an identified difficult airway, the provider may elect to try another approach where the patient remains awake for the procedure, such as nasal, awake oral, or fiberoptic intubation. It is interesting to note, however, that RSI is the most common means of intubating ED patients after a failed approach in an awake patient.37 If it is determined that oral intubation will be impossible, RSI should not be attempted. Cases of impossible laryngoscopy may include massive angioedema, advanced Ludwig’s angina, a wired jaw or readily apparent derangements in facial or oral anatomy, and cervical spine or mandibular immobility. When it is anticipated that oral intubation may be difficult, a failed airway plan should be agreed on, and all of the appropriate equipment should be readily available.
A Planned Stepwise Approach to RSI The basic premises of RSI are listed in Table 2, and a generally accepted stepwise approach to RSI is listed in Figure 1. Preparation for RSI may begin in advance of patient contact. Readying and testing equipment (including backup devices), drawing up medications, and calculating dosages in some cases, if weight is known, may be done en route to the patient. Using a preprinted card with all the RSI drugs and dosages listed as a checklist may avoid medication errors or omissions. Once at the patient, reliable intravenous access, electrocardiogram monitor, blood pressure, pulse oximetry, and ETCO2 should be obtained. The patient should be placed in a protected environment if possible and positioned to allow the best access to the airway for the person performing intubation. Preoxygenation should be accomplished with 100% oxygen. One of the primary goals of RSI is to avoid external ventilation and filling the stomach with air before paralysis whenever possible, so a staged approach to oxygenation should be taken. If the patient is breathing spontaneously, oxygen administration through a nonrebreather mask for 5 minutes without interposed ventilations is preferred. If 95% to 100% oxygen saturation cannot be obtained solely with a nonrebreather mask, the patient should be assisted with coordinated BVM ventilations, which are synchronous to respiratory efforts to minimize gastric filling. Finally, if the patient is not breathing spontaneously, assuming control with BVM may be necessary to provide sufficient oxygenation. Pretreatment medications are available to attenuate the physiologic responses to laryngoscopy and intubation and to offset anticipated medication effects of some RSI medications. These may include intravenous fluids to offset hypotension from some sedative/induction agents, lidocaine to blunt the response to laryngoscopy and attenuate intracranial pressure (ICP) increase, opioids to provide analgesia and attenuate sympathetic response to intubation, benzodiazepines for anxiolysis, atropine to offset bradycardia in pediatric patients and Air Medical Journal 24:1
adults receiving a second dose of succinylcholine, and defasciculating doses of nondepolarizing neuromuscular blocking agents to mitigate potential ICP increase by succinylcholine. The ideal sedative/induction agent for RSI would smoothly provide rapid unconsciousness, amnesia, and analgesia. It would maintain cerebral perfusion pressure and cardiovascular hemodynamics and have few side effects. No ideal agent exists, but several options are available for prehospital RSI— barbiturates, benzodiazepines, opioids, etomidate, ketamine, and propofol. Certain sedative agents (thiopental, methohexital, and propofol) have been shown to complement incomplete paralysis and facilitate RSI in the ED.38 Midazolam, a benzodiazepine, and etomidate are the most commonly used sedatives for RSI in air medical transport systems.12 Etomidate has been reported to be associated with high intubation success rates and low rates of adverse hemodynamic effects in the air medical setting.10,33,34 Midazolam has been reported to result in dose-dependent hypotension39 and is frequently underdosed for ED and prehospital RSI.34,40 Neuromuscular blockade for prehospital RSI is accomplished most often with the depolarizing agent succinylcholine.12,41 Succinylcholine has a rapid onset (45-60 s) and a short duration of action (6-10 min), making it the most useful agent for RSI. The side effect profile of succinylcholine is its major drawback and includes fasciculations, hyperkalemia, bradycardia, malignant hyperthermia, and masseter muscle spasm. Many nondepolarizing agents are available, and these are used primarily for postintubation paralysis. If used for RSI, they generally have a slower onset and a much longer duration of action than succinylcholine. These agents may be used when succinylcholine is contraindicated. The most useful nondepolarizing agent for RSI is rocuronium, which has an action onset of 45 to 60 seconds and duration of 40 minutes.42 A sample RSI protocol for pretreatment, sedation, and neuromuscular blockade is listed in Table 3. Cricoid pressure should be applied as soon as the patient loses consciousness and before complete paralysis from RSI medications to prevent passive regurgitation of gastric contents into the lungs. Cricoid pressure should be maintained until ET tube position is verified in the trachea. If it is necessary to assist ventilation with a BVM before successful intubation, cricoid pressure should be maintained to limit gastric distention. However, this pressure may impair the intubator’s view of the glottis, and transient release of pressure to perform ELM or a BURP maneuver may be required. Laryngoscopy and intubation can proceed when the patient is flaccid and has no resistance to jaw opening, typically a minimum of 45 seconds after succinylcholine administration. Intubation attempts should be suspended if the patient’s oxygen saturation drops below 90% and ventilation initiated before reattempting laryngoscopy. Confirmation of ET tube placement within the trachea is critical and should be accomplished by clinical, objective measures, such as ETCO2 detection or syringe or bulb aspiration technique in every patient. The ET tube should be secured and depth should be noted and monitored. Pulse oximetry should be continuously monitored. Postintubation management includes administering medJanuary-February 2005
Figure 1. Stepwise Approach to Rapid Sequence Intubation Preparation and positioning
Preoxygenation
Pretreatment
Sedation
Paralysis
Cricoid pressure
Laryngoscopy and intubation
Confirmation of placement
Postintubation management
ications for prolonged paralysis and sedation and continued monitoring. Continuous ECG, pulse oximetry, and ETCO2 (if available) monitoring should occur. Reconfirmation of ET tube position should be performed after each patient movement or clinical deterioration.
Backup Methods for Failed RSI Programs using RSI must have protocols and equipment necessary for managing failed intubation. Air medical systems should be prepared to use at least 1 noninvasive and 1 invasive (surgical) backup technique. There are many techniques and devices for failed intubation rescue. Devices that are simple, fast, easy, versatile, and inexpensive are the most useful for prehospital systems. Flight programs generally perform a higher volume of airway procedures and have fewer vehicles to stock than EMS ground systems and may be able to justify using more expensive devices. The noninvasive rescue devices that have been used for failed prehospital intubation are the esophageal-tracheal combitube,43 laryngeal mask airway,44,45 intubating laryngeal mask airway (ILMA), 46,47 and ET tube introducer (gum elastic bougie).48-50 An advantage to the ILMA airway and the ET tube introducer are that they may result in a cuffed tube placed in the trachea. Invasive or surgical options include cricothyrotomy and translaryngeal jet ventilation. The latter is 43
Table 3 A SAMPLE RSI PROTOCOL FOR PRETREATMENT, SEDATION, AND PARALYSIS PRETREATMENT* • Vecuronium 0.01 mg/kg IV • Lidocaine 1.5 mg/kg IV • Fentanyl 3 mg/kg IV • Atropine 0.02 mg/kg IV (Minimum dose of 0.1 mg) SEDATION Etomidate 0.3 mg/kg IV PARALYSIS Succinylcholine 1.5 mg/kg IV
Defasciculating agent for patients with head trauma or at risk for increased intracranial pressure (ICP) For patients with head trauma or at risk for increased ICP For patients with head trauma or at risk for increased ICP, ischemic heart disease, aneurysm, or dissection For any child < 1 year old undergoing laryngoscopy, any child 1-10 years old receiving succinylcholine, or adolescents and adults receiving a repeat dose of succinylcholine Use 0.15 mg/kg IV in hypotensive or unstable patients Use 2 mg/kg IV in children less than 10 years old; 3 mg/kg IV in infants and neonates
*Pretreatment medications should be administered 3 minutes before intubation.
Figure 2. A Sample Failed Rapid-Sequence Intubation Algorithm for Adolescents and Adults
Failed RSI 3 unsuccessful attempts at laryngoscopy or Inability to ventilate during RSI with a BVM (SpO2 < 90%) after single laryngoscopy attempt
ILMA Placement
Reattempt ILMA or Transport with BVM ventilation
Successful ventilation with ILMA?
Yes
Yes Successful ETT placement through ILMA?
BVM maintains SpO2 ≥ 90%?
No
No
Cricothyrotomy No
Yes Transportation with postintubation management
No
Is ventilation with ILMA alone sufficient for transport? Yes Reattempt ETT placement throught ILMA or Transport with ILMA ventilation
particularly useful in pediatric patients in whom cricothyrotomy is contraindicated. A sample failed RSI algorithm for adolescents and adults is listed in Figure 2.
Confirmation and Monitoring Verification of ET tube placement after RSI in the prehospital setting is critical. Unrecognized esophageal place44
ment can rapidly prove fatal in the sedated and paralyzed patient and is unacceptable. Clinical indicators of tube placement—such as visualization of the ET tube passing through the cords, auscultation of breath sounds, absence of sounds over the epigastrum, symmetric chest rise and fall with ventilation, and presence of condensation in the ET tube—have been shown to be unreliable in the hospital. Air Medical Journal 24:1
They are likely to be even less useful in the prehospital setting where adverse environmental conditions exist. Recent studies on the rate of unrecognized misplaced ET tubes after prehospital intubation are alarming. Katz and Falk20 reported that 25% of patients intubated by paramedics had unrecognized misplaced ET tubes (17% esophageal and 8% hypopharyngeal). Jemmett et al21 found the rate of unrecognized misplaced ET tubes by EMS personnel to be 12% (9% esophageal, 2% right main stem, 1% hypopharyngeal). These reports underscore the need for the consistent use of objective measures of placement confirmation. The depth of the ET tube should be noted and “objective” measures, such as ETCO2 detection or aspiration esophageal detector devices, should be used on every prehospital intubation. ETCO2 can be detected by colorimetric detectors, qualitative detectors, or quantitative capnography. The presence of CO2 strongly suggests placement in the trachea. Second line devices, such as syringe or bulb aspiration esophageal detector devices, are not as reliable as ETCO2 but may be useful in cases of prolonged cardiac arrest where cessation of CO2 production may have occurred. An airway management reporting form, detailing means of confirmation, may help ensure use of multiple confirmation measures and avoid esophageal airway deaths. ET tube position should be reconfirmed after each movement of the patient or with any deterioration of patient condition. Ongoing monitoring of electrocardiogram, blood pressure, pulse oximetry, and ETCO2 should occur during transport to prevent hypotension, hypoxia, and hyperventilation.
Conclusion Recent reports have highlighted controversies surrounding prehospital intubation and RSI. Air medical transport programs generally have smaller numbers of personnel who have frequent contact with the high acuity patients requiring airway management and can cover large geographic areas. Air medical providers are ideal candidates for performing prehospital RSI. This responsibility requires commitment to training and quality improvement. The goals for air medical RSI programs are intubation success rates comparable to the hospital setting, limited attempts at intubation, early recognition and avoidance of misplaced ET tubes, and prevention of hypoxia, hypotension, and hyperventilation before, during, and after intubation. Achieving these goals requires programs to have strong medical oversight, excellent intubation techniques, training and quality improvement for airway management, skill at selecting appropriate methods for airway management, a planned stepwise approach to RSI, adequate backup methods for failed RSI, procedures to confirm ET tube placement, and ongoing patient monitoring.
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Air Medical Journal 24:1
ABSTRACT Airway management is an essential component of the air medical transport of critically ill or injured patients. Many controversies surround the use of rapid sequence intubation (RSI) in the prehospital setting. The challenges of establishing an airway in this environment may exceed those in the hospital. However, it is clear that the same high standards for success demanded in the hospital must be applied to RSI in the prehospital setting for the practice to be accepted and result in positive outcomes. Given their volume of high acuity patients, air medical providers are ideal candidates for performing prehospital RSI. Undertaking this responsibility requires commitment to training and quality improvement. We present the components required to establish and maintain a successful air medical RSI program.
Introduction Airway management is an essential component of the air medical transport of critically ill or injured patients. Indeed, obtaining an airway is one of the fundamental skills of air medical prehospital providers.1,2 Challenges to intubation in the prehospital setting include nonfasted, awake, or combative patients with intact airway reflexes making intubation difficult or impossible. For this reason, prehospital airway management has been reported with highly variable success rates in a variety of emergency medical services (EMS) settings. Rapid sequence intubation (RSI) is defined as the use of a sedative/induction agent and a neuromuscular blocking agent to facilitate intubation. The potential advantages of RSI include fewer intubation attempts, fewer complications, increased overall success rate, and decreased physiologic stress to the patient. RSI has emerged as the preferred method for airway management in the air medical setting.2-11 A recent survey of 196 air medical programs found that, of the 114 respondents, 93% of the programs used RSI.12 Several recent articles have highlighted controversies regarding the use of prehospital intubation and RSI. Gausche et al13 reported that the addition of out-of-hospital endotracheal intubation to a paramedic scope of practice that already includes bag/valve/mask ventilation (BVM) did not improve survival or neurological outcome of pediatric patients treated in an urban EMS system. The initial results of the San Diego Paramedic RSI trial reported an intubation success rate of only 40
84.2% in patients with severe head injury undergoing RSI.14 An accompanying editorial points out that that RSI should enable prehospital providers to achieve successful intubation rates similar to those seen in the hospital. They say the 15% failure rate in the San Diego trial did not meet the in-hospital expectation that RSI should “never or rarely fail.”15 The controversy over prehospital intubation and RSI is not limited to ground EMS programs. In 2002 Mizelle et al16 presented 3 cases of preventable morbidity and mortality from prehospital paralytic-assisted intubation in the air medical setting. Recently, 2 outcome studies have reported increased morbidity and mortality in patients with head injury undergoing prehospital intubation compared with in-hospital intubation.17,18 One of these was from the San Diego Paramedic RSI trial, and the results prompted suspension of the trial and discontinuation of their RSI protocol.18 Given the recent controversy over prehospital intubation and RSI, the following questions remain: What is the role of air medical programs in providing prehospital airway management? Can prehospital air medical RSI success rates approach those of in-hospital rates? Does air medical RSI improve patient outcome? In an attempt to address these questions, we present the components required to establish and maintain a successful air medical prehospital RSI program.
Goals for a Successful Prehospital RSI Program Prehospital RSI success rates should be comparable with in-hospital rates. The challenges of establishing an airway in the prehospital
Division of Emergency Medicine and AirMed, University of Utah Health Sciences Center, Salt Lake City Address for correspondence: Eric R. Swanson, MD, Division of Emergency Medicine, 1150 Moran Bldg., 175 N. Medical Dr., Salt Lake City, UT 84132; [email protected] 1067-991X/$30.00 Copyright 2005 by Air Medical Journal Associates doi:10.1016/j.amj.2004.10.008
Air Medical Journal 24:1
setting may exceed those seen in the hospital arena. However, it is clear that the same high standards for success must be applied to RSI in the prehospital setting for the practice to be accepted and achieve the improved outcomes seen in other settings. The training of prehospital providers needs to have the same standards and scrutiny of practice as seen in the hospital setting. Medical director involvement and quality-improvement programs to monitor ongoing success are essential.
Table 1
Multiple intubation attempts must be limited.
4. Standardized RSI protocols
Preliminary work suggests that multiple intubation attempts are associated with an increased risk of field death.19 Early recognition of a difficult or failed airway will limit further futile attempts at intubation. Backup or rescue devices must be available and used immediately on recognition of a failed airway in a preplanned, systemwide approach.
5. Backup rescue airway methods
Misplaced endotracheal tubes must be avoided. Several studies have reported the incidence of misplaced endotracheal (ET) tubes to be unacceptably high with prehospital intubation.20,21 Misplaced or dislodged ET tubes have been associated with an increased risk of field or emergencydepartment (ED) death.19 The depth of the ET tube should be noted and “objective” measures [end-tidal CO2 (ETCO2) detection and/or aspiration devices] should be used on every prehospital intubation. Continuous vigilance and monitoring of ET tube placement must be maintained.
Patients must be closely monitored, and hyperventilation, hypoxia, and hypotension must be avoided. Recent reports from the San Diego investigators are shedding some light on the potential reasons for the observed increase in morbidity and mortality associated with prehospital RSI in patients with traumatic brain injury. Dunford et al22 reported a concerning incidence of oxygen desaturation (57%) and bradycardia (19%) in a subset of patients undergoing prehospital RSI. Davis et al23 found that air medical transport of paramedic RSI patients is associated with improved outcomes, suggesting that air medical crews may provide superior postintubation management compared with their ground counterparts.
Steps Toward Improving Prehospital RSI Success Several components of an RSI program must be in place to achieve the goals outlined above. In a position paper on prehospital RSI, the National Association of EMS Physicians (NAEMSP)24 identified 6 minimum elements necessary for a prehospital RSI program (Table 1). Air medical transport programs should incorporate these minimum elements into their RSI programs. The first element listed is medical direction and supervision. This aspect is the most crucial of a prehospital RSI program, and all of the other elements are more likely to be achieved in the presence of a motivated and involved medical director. Improving prehospital RSI success requires programs to improve intubation technique, institute training and quality improvement for intubation and RSI, select appropriate methods for airway management, have a planned stepwise January-February 2005
NAEMSP MINIMUM ELEMENTS FOR PREHOSPITAL RAPID SEQUENCE INTUBATION PROGRAMS 1. Medical direction and supervision 2. Training and continuing education 3. Resources for patient monitoring, drug storage and delivery, confirmation and monitoring of ET tube placement
6. Continuing quality assurance and performance review
approach to RSI, have adequate backup methods for failed RSI, and have procedures in place to confirm ET tube placement and ongoing patient monitoring.
Improving Intubation Technique Personnel who perform RSI should have substantial intubation experience. Even experienced providers may have had little formal laryngoscopy training, and the first step to any prehospital RSI program should be to establish a foundation of basic airway management and laryngoscopy skills. Techniques have been described that can improve glottic visualization and intubation success. Cricoid pressure (a necessary component of RSI) may worsen glottic visualization. The BURP (backward, upward, rightward pressure) maneuver was designed to improve glottic visualization but requires a second operator who is blinded to what that intubator sees.25 External laryngeal manipulation (ELM) or bimanual intubation consists of the intubator using his or her free right hand to manipulate the larynx to obtain the best visualization of the glottic opening. Once the best view has been obtained, a second operator holds the larynx in the ideal position. ELM has been shown to improve laryngeal view during intubation.26,27 Knopp28 has stated that ELM is a technique that emergency physicians should incorporate into their practice as one of the essential skills for tracheal intubation. We agree with this statement and believe that all air medical personnel performing intubation should be familiar with this technique. The shape of the ET tube stylet also may have an effect on visualization of the glottic opening and ability to maneuver the tip of the ET tube. Preliminary work suggests that a stylet shape that is straight to the balloon, then angled at 30 to 40 degrees, compared with a gentle curve, permits better glottic and ET tube tip visualization and improves maneuverability within the hypopharynx.29
Training and Quality Improvement for Intubation and RSI No standard training curriculum exists for air medical RSI, although several studies have described training regimens for implementing RSI programs. Training was varied, with several programs using operating-room time for initial or ongoing training.4,6,9,11,30 Cadaver, manikin, and animal models have 41
Table 2 BASIC PREMISES OF RAPID SEQUENCE INTUBATION 1. All patients are assumed to have a full stomach. 2. Interposed ventilations should be avoided whenever possible to prevent gastric filling before intubation. 3. Use of both an induction (sedative) agent and paralytic maximizes visualization and completely controls the patient. 4. Induction doses are meant to cause unconscious sedation and are typically 2 to 3 times higher than those used in “conscious” sedation. 5. Cricoid pressure should be used to prevent passive regurgitation.
been used for airway skills laboratories.2,4,10,11 Several studies described an ongoing requirement to perform a certain number of intubations during a defined period.2,4,10,11,31 Training in prehospital RSI is necessarily variable, reflecting skills, environments, and requirements encountered in different systems. The skill of airway management has been shown to decline after initial training, but independent practice and periodic observation with feedback have been shown to be effective in maintaining performance.32 We previously described the effect of an airway education program consisting of initial orientation, continuing education, and quality improvement on prehospital intubation in an air medical service already using RSI.11 That study demonstrated an increase in the use of RSI, a dramatic decrease in the use of neuromuscular blockade without sedation, and a decrease in cricothyrotomy rate after the institution of an airway education program. This program has shown success rates of 98% to 100% with prehospital RSI in the air medical setting.33,34 One of the difficulties in performing quality improvement and research with prehospital intubation is the lack of uniform definitions, terminology, and reporting formats. Recently the National Association of EMS Physicians issued a position paper recommending guidelines for uniform reporting of data from out-of-hospital airway management.35 The paper recommends that all EMS systems monitor the quality of outof-hospital airway management procedures. A template of the uniform airway management data form may be obtained from the group’s Web site (www.naemsp.org). At a minimum, the quality-improvement process should involve a systemwide review of all airway management encounters and a detailed educational dissection of any difficult or failed airway incidents.
Selecting Appropriate Methods for Airway Management Using RSI provides the fastest and most effective way of obtaining a definitive airway. Some patients are unable to be intubated by the oral route during RSI, putting them at considerable risk because they no longer have spontaneous ventilation. The failed intubation rate in the anesthesia literature is 0.1 to 0.4% and around 1% in the ED setting. This number 42
may be higher in the prehospital setting, where conditions are not controlled. The ideal situation would be to identify all patients in whom intubation will fail before administering RSI medications. Unfortunately, many of the methods and screening tests available for detecting the difficult airway have been shown to have limited use in ED patients undergoing intubation. 36 In the case of an identified difficult airway, the provider may elect to try another approach where the patient remains awake for the procedure, such as nasal, awake oral, or fiberoptic intubation. It is interesting to note, however, that RSI is the most common means of intubating ED patients after a failed approach in an awake patient.37 If it is determined that oral intubation will be impossible, RSI should not be attempted. Cases of impossible laryngoscopy may include massive angioedema, advanced Ludwig’s angina, a wired jaw or readily apparent derangements in facial or oral anatomy, and cervical spine or mandibular immobility. When it is anticipated that oral intubation may be difficult, a failed airway plan should be agreed on, and all of the appropriate equipment should be readily available.
A Planned Stepwise Approach to RSI The basic premises of RSI are listed in Table 2, and a generally accepted stepwise approach to RSI is listed in Figure 1. Preparation for RSI may begin in advance of patient contact. Readying and testing equipment (including backup devices), drawing up medications, and calculating dosages in some cases, if weight is known, may be done en route to the patient. Using a preprinted card with all the RSI drugs and dosages listed as a checklist may avoid medication errors or omissions. Once at the patient, reliable intravenous access, electrocardiogram monitor, blood pressure, pulse oximetry, and ETCO2 should be obtained. The patient should be placed in a protected environment if possible and positioned to allow the best access to the airway for the person performing intubation. Preoxygenation should be accomplished with 100% oxygen. One of the primary goals of RSI is to avoid external ventilation and filling the stomach with air before paralysis whenever possible, so a staged approach to oxygenation should be taken. If the patient is breathing spontaneously, oxygen administration through a nonrebreather mask for 5 minutes without interposed ventilations is preferred. If 95% to 100% oxygen saturation cannot be obtained solely with a nonrebreather mask, the patient should be assisted with coordinated BVM ventilations, which are synchronous to respiratory efforts to minimize gastric filling. Finally, if the patient is not breathing spontaneously, assuming control with BVM may be necessary to provide sufficient oxygenation. Pretreatment medications are available to attenuate the physiologic responses to laryngoscopy and intubation and to offset anticipated medication effects of some RSI medications. These may include intravenous fluids to offset hypotension from some sedative/induction agents, lidocaine to blunt the response to laryngoscopy and attenuate intracranial pressure (ICP) increase, opioids to provide analgesia and attenuate sympathetic response to intubation, benzodiazepines for anxiolysis, atropine to offset bradycardia in pediatric patients and Air Medical Journal 24:1
adults receiving a second dose of succinylcholine, and defasciculating doses of nondepolarizing neuromuscular blocking agents to mitigate potential ICP increase by succinylcholine. The ideal sedative/induction agent for RSI would smoothly provide rapid unconsciousness, amnesia, and analgesia. It would maintain cerebral perfusion pressure and cardiovascular hemodynamics and have few side effects. No ideal agent exists, but several options are available for prehospital RSI— barbiturates, benzodiazepines, opioids, etomidate, ketamine, and propofol. Certain sedative agents (thiopental, methohexital, and propofol) have been shown to complement incomplete paralysis and facilitate RSI in the ED.38 Midazolam, a benzodiazepine, and etomidate are the most commonly used sedatives for RSI in air medical transport systems.12 Etomidate has been reported to be associated with high intubation success rates and low rates of adverse hemodynamic effects in the air medical setting.10,33,34 Midazolam has been reported to result in dose-dependent hypotension39 and is frequently underdosed for ED and prehospital RSI.34,40 Neuromuscular blockade for prehospital RSI is accomplished most often with the depolarizing agent succinylcholine.12,41 Succinylcholine has a rapid onset (45-60 s) and a short duration of action (6-10 min), making it the most useful agent for RSI. The side effect profile of succinylcholine is its major drawback and includes fasciculations, hyperkalemia, bradycardia, malignant hyperthermia, and masseter muscle spasm. Many nondepolarizing agents are available, and these are used primarily for postintubation paralysis. If used for RSI, they generally have a slower onset and a much longer duration of action than succinylcholine. These agents may be used when succinylcholine is contraindicated. The most useful nondepolarizing agent for RSI is rocuronium, which has an action onset of 45 to 60 seconds and duration of 40 minutes.42 A sample RSI protocol for pretreatment, sedation, and neuromuscular blockade is listed in Table 3. Cricoid pressure should be applied as soon as the patient loses consciousness and before complete paralysis from RSI medications to prevent passive regurgitation of gastric contents into the lungs. Cricoid pressure should be maintained until ET tube position is verified in the trachea. If it is necessary to assist ventilation with a BVM before successful intubation, cricoid pressure should be maintained to limit gastric distention. However, this pressure may impair the intubator’s view of the glottis, and transient release of pressure to perform ELM or a BURP maneuver may be required. Laryngoscopy and intubation can proceed when the patient is flaccid and has no resistance to jaw opening, typically a minimum of 45 seconds after succinylcholine administration. Intubation attempts should be suspended if the patient’s oxygen saturation drops below 90% and ventilation initiated before reattempting laryngoscopy. Confirmation of ET tube placement within the trachea is critical and should be accomplished by clinical, objective measures, such as ETCO2 detection or syringe or bulb aspiration technique in every patient. The ET tube should be secured and depth should be noted and monitored. Pulse oximetry should be continuously monitored. Postintubation management includes administering medJanuary-February 2005
Figure 1. Stepwise Approach to Rapid Sequence Intubation Preparation and positioning
Preoxygenation
Pretreatment
Sedation
Paralysis
Cricoid pressure
Laryngoscopy and intubation
Confirmation of placement
Postintubation management
ications for prolonged paralysis and sedation and continued monitoring. Continuous ECG, pulse oximetry, and ETCO2 (if available) monitoring should occur. Reconfirmation of ET tube position should be performed after each patient movement or clinical deterioration.
Backup Methods for Failed RSI Programs using RSI must have protocols and equipment necessary for managing failed intubation. Air medical systems should be prepared to use at least 1 noninvasive and 1 invasive (surgical) backup technique. There are many techniques and devices for failed intubation rescue. Devices that are simple, fast, easy, versatile, and inexpensive are the most useful for prehospital systems. Flight programs generally perform a higher volume of airway procedures and have fewer vehicles to stock than EMS ground systems and may be able to justify using more expensive devices. The noninvasive rescue devices that have been used for failed prehospital intubation are the esophageal-tracheal combitube,43 laryngeal mask airway,44,45 intubating laryngeal mask airway (ILMA), 46,47 and ET tube introducer (gum elastic bougie).48-50 An advantage to the ILMA airway and the ET tube introducer are that they may result in a cuffed tube placed in the trachea. Invasive or surgical options include cricothyrotomy and translaryngeal jet ventilation. The latter is 43
Table 3 A SAMPLE RSI PROTOCOL FOR PRETREATMENT, SEDATION, AND PARALYSIS PRETREATMENT* • Vecuronium 0.01 mg/kg IV • Lidocaine 1.5 mg/kg IV • Fentanyl 3 mg/kg IV • Atropine 0.02 mg/kg IV (Minimum dose of 0.1 mg) SEDATION Etomidate 0.3 mg/kg IV PARALYSIS Succinylcholine 1.5 mg/kg IV
Defasciculating agent for patients with head trauma or at risk for increased intracranial pressure (ICP) For patients with head trauma or at risk for increased ICP For patients with head trauma or at risk for increased ICP, ischemic heart disease, aneurysm, or dissection For any child < 1 year old undergoing laryngoscopy, any child 1-10 years old receiving succinylcholine, or adolescents and adults receiving a repeat dose of succinylcholine Use 0.15 mg/kg IV in hypotensive or unstable patients Use 2 mg/kg IV in children less than 10 years old; 3 mg/kg IV in infants and neonates
*Pretreatment medications should be administered 3 minutes before intubation.
Figure 2. A Sample Failed Rapid-Sequence Intubation Algorithm for Adolescents and Adults
Failed RSI 3 unsuccessful attempts at laryngoscopy or Inability to ventilate during RSI with a BVM (SpO2 < 90%) after single laryngoscopy attempt
ILMA Placement
Reattempt ILMA or Transport with BVM ventilation
Successful ventilation with ILMA?
Yes
Yes Successful ETT placement through ILMA?
BVM maintains SpO2 ≥ 90%?
No
No
Cricothyrotomy No
Yes Transportation with postintubation management
No
Is ventilation with ILMA alone sufficient for transport? Yes Reattempt ETT placement throught ILMA or Transport with ILMA ventilation
particularly useful in pediatric patients in whom cricothyrotomy is contraindicated. A sample failed RSI algorithm for adolescents and adults is listed in Figure 2.
Confirmation and Monitoring Verification of ET tube placement after RSI in the prehospital setting is critical. Unrecognized esophageal place44
ment can rapidly prove fatal in the sedated and paralyzed patient and is unacceptable. Clinical indicators of tube placement—such as visualization of the ET tube passing through the cords, auscultation of breath sounds, absence of sounds over the epigastrum, symmetric chest rise and fall with ventilation, and presence of condensation in the ET tube—have been shown to be unreliable in the hospital. Air Medical Journal 24:1
They are likely to be even less useful in the prehospital setting where adverse environmental conditions exist. Recent studies on the rate of unrecognized misplaced ET tubes after prehospital intubation are alarming. Katz and Falk20 reported that 25% of patients intubated by paramedics had unrecognized misplaced ET tubes (17% esophageal and 8% hypopharyngeal). Jemmett et al21 found the rate of unrecognized misplaced ET tubes by EMS personnel to be 12% (9% esophageal, 2% right main stem, 1% hypopharyngeal). These reports underscore the need for the consistent use of objective measures of placement confirmation. The depth of the ET tube should be noted and “objective” measures, such as ETCO2 detection or aspiration esophageal detector devices, should be used on every prehospital intubation. ETCO2 can be detected by colorimetric detectors, qualitative detectors, or quantitative capnography. The presence of CO2 strongly suggests placement in the trachea. Second line devices, such as syringe or bulb aspiration esophageal detector devices, are not as reliable as ETCO2 but may be useful in cases of prolonged cardiac arrest where cessation of CO2 production may have occurred. An airway management reporting form, detailing means of confirmation, may help ensure use of multiple confirmation measures and avoid esophageal airway deaths. ET tube position should be reconfirmed after each movement of the patient or with any deterioration of patient condition. Ongoing monitoring of electrocardiogram, blood pressure, pulse oximetry, and ETCO2 should occur during transport to prevent hypotension, hypoxia, and hyperventilation.
Conclusion Recent reports have highlighted controversies surrounding prehospital intubation and RSI. Air medical transport programs generally have smaller numbers of personnel who have frequent contact with the high acuity patients requiring airway management and can cover large geographic areas. Air medical providers are ideal candidates for performing prehospital RSI. This responsibility requires commitment to training and quality improvement. The goals for air medical RSI programs are intubation success rates comparable to the hospital setting, limited attempts at intubation, early recognition and avoidance of misplaced ET tubes, and prevention of hypoxia, hypotension, and hyperventilation before, during, and after intubation. Achieving these goals requires programs to have strong medical oversight, excellent intubation techniques, training and quality improvement for airway management, skill at selecting appropriate methods for airway management, a planned stepwise approach to RSI, adequate backup methods for failed RSI, procedures to confirm ET tube placement, and ongoing patient monitoring.
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