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Airway Management in Critical Illness
Journal Pre-proof Airway Management in Critical Illness: An Update J. Aaron Scott, DO, Stephen O. Heard, MD, Maksim Zayaruzny, MD MS-HPEd, J. Matthias Walz, MD PII:
S0012-3692(19)34193-5
DOI:
https://doi.org/10.1016/j.chest.2019.10.026
Reference:
CHEST 2703
To appear in:
CHEST
Received Date: 15 April 2019 Revised Date:
5 October 2019
Accepted Date: 9 October 2019
Please cite this article as: Scott JA, Heard SO, Zayaruzny M, Walz JM, Airway Management in Critical Illness: An Update, CHEST (2019), doi: https://doi.org/10.1016/j.chest.2019.10.026. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Copyright © 2019 Published by Elsevier Inc under license from the American College of Chest Physicians.
Airway Management in Critical Illness: An Update
J. Aaron Scott, DO; Stephen O. Heard, MD; Maksim Zayaruzny, MD MS-HPEd; J. Matthias Walz, MD
From the Department of Anesthesiology and Perioperative Medicine, Division of Critical Care Medicine UMass Memorial Medical Center, Worcester, MA
Correspondence:
J. Aaron Scott, DO Department of Anesthesiology UMass Memorial Medical Center 55 Lake Avenue North Worcester MA 01655
Abstract
Expertise in airway management is a vital skill for any provider caring for critically ill patients. A growing body of literature has identified the stark difference in peri-procedural outcomes of elective intubation in the operating room when compared to emergency intubation in the intensive care unit (ICU). A number of strategies to reduce the morbidity and mortality associated with airway management in the critically ill have been described. In this review, we will provide an updated framework for airway assessment before direct laryngoscopy (DL) and video laryngoscopy (VL), utilization of newer pharmacologic agents, comment on current concepts in tracheal intubation in the ICU, and address human factors around critical decisionmaking during ICU airway management.
Introduction Over the past decade, advances have been made towards decreasing the morbidity and mortality associated with airway management in critical illness. Since the publication of our last review article 1, the critical care community has seen broad adoption of video-laryngoscopy (VL), introduction of new pharmacological agents, and publication of high-quality research around protocol driven airway management. To provide this update and review of airway management in critical illness in adult patients we searched PubMed, Embase, Scopus, Google Scholar, the Cochrane Library (Cohrane Collaboration), and references of articles retrieved. Publications from 2007 through June of 2019 were then examined for relevancy and integrated. For a detailed list of search terms used please see Additional file 1. For the purpose of this review, we assume that the reader has basic knowledge of airway anatomy and is proficient in basic principles of airway management.
We will discuss the validation of the MACHOCHA score (Mallamapati class, presence of obstructive sleep Apnea OSA, Cervical spine mobility, mouth Opening, presence of Coma or Hypoxia, and presence of an Anesthesiologist) for airway assessment before DL, predictors of difficult VL, airway kit and checklist utilization, as well as patient positioning and adjunctive oxygen delivery device use. Additionally, we discuss the role of VL in the ICU, controversies around Rapid Sequence Intubation (RSI), and provide an updated summary on the most frequently used pharmacologic agents to facilitate ICU-intubation. Lastly, we review the relevant literature on human factors in airway management.
Morbidity and Mortality Associated with ICU Intubations
Expertise in airway management is a vital skill for any provider caring for critically ill patients. As compared to elective airway management in the operating room (OR), securing an airway in the ICU poses unique challenges and is associated with increased morbidity and mortality. In a one-year review of all National Health Service hospitals in the United Kingdom (UK), the 4th National Audit Project (NAP4) study examined major airway complications during anesthesia, including death, brain damage, emergency surgical airway and unanticipated ICU admission. The study found 46 events per million general anesthetics, or one in 22,000, and an associated mortality rate of 5.6 per million 2. Published data from the United States (US) show a mortality rate of 1.1 per million for patients undergoing general anesthetics 3.
A review of the literature examining airway management in the ICU paints a different picture. In 2004, Mort et al. identified that emergent intubation (EI) in remote locations, such as the ICU, resulted in a 1 in 50 rate of cardiac arrest 4. The predominant etiology of arrest in 83% of cases was hypoxemia, defined as any reduction in oxygen saturation (SpO2) < 90% if preoxygenated SpO2 was > 90%. Furthermore, in 63% of cases the hypoxemia was identified as being secondary to esophageal intubation.
These findings have been further supported by the second part of NAP4 where 25% of reported airway events occurred in the ICU and Emergency Department (ED) 5. Sixty-one percent of these events resulted in permanent patient harm or death: a 58-fold higher risk for emergent airway intervention in the ICU/ED as compared to elective airway management in the OR. Nearly 15 years after the publication of Mort, et al., De Jong et al. identified a rate of 1 in 40 cardiac arrests in ICU intubations that was associated with an increased risk of 28-day mortality
(hazard ratio = 3.9 [2.4-6.3]) 6. Factors predictive of peri-intubation cardiovascular collapse and cardiac arrest are presented in Table 1.
Airway Assessment Many commonly used methods for elective intubation are not feasible for ICU patients. According to one study, only 26 % of the patients requiring DL EI in the emergency department were able to cooperate with a Mallampati test 7. Another retrospective single center review of 838 patients documented that all of the RSI failures, and up to two thirds of non-cardiac arrest intubations, could not have undergone Mallampati scoring, neck mobility testing, or thyromental distance measurements 8. If assessible, inability to reach the lower incisors to the upper lip is a cautionary feature9.
More recently, a scoring methodology that combines anatomic, physiologic and operator characteristics was developed and validated in a multicenter study 10. The MACOCHA score uses a 12-point scale based on 7 independent predictors of difficult intubation with DL. Higher MACOCHA scores were associated with an increasing risk of difficult intubation. The investigators observed a sensitivity of 73%, specificity of 83%, a negative predictive value of 98%, and a positive predictive value of 36% (Table 2).
Despite the near ubiquitous presence of VL in the OR, ED and ICU, fewer data exist regarding predictors of difficult VL. DL failure is frequently associated with inability to visualize the glottis, whereas failure in VL is often related to inability to pass the endotracheal tube11. Airway
edema, blood in the airway, cervical immobility, obesity and small mouth opening have been associated with higher odds of first attempt failure 12,13.
Preparation for endotracheal intubation, Patient Positioning, and Rapid Sequence Intubation (RSI) Team approach and protocols Prior to airway instrumentation, conditions for intubation should be as close to ideal as possible. Several advances have been embraced from other areas of ICU care to become a part of optimal preparation for intubation. Following the broad adoption of the checklist to prevent central line associated bloodstream infections, other areas of medicine have utilized a similar approach to standardize processes and achieve improvements in patient safety and outcomes 14. Often high fidelity simulation is the entry arena used to familiarize trainees with new protocols. A kit or cart with all of the necessary supplies to facilitate invasive procedures is optimal to avoid the need for securing essential equipment at the last minute. In addition, some data suggest that a team approach with a defined intubation algorithm is beneficial in reducing complications related to EI 15-17.
Patient positioning The utility of the sniffing position for intubations outside of the operating room is unknown. A recent randomized trial of the “ramped” position (head of bed elevated 25 degrees, face parallel to the floor) vs “sniffing” position (torso supine, neck flexed, head extended) in critically ill adults with an average BMI of 27 found that a “ramped” position increased difficulty in laryngeal exposure, increased incidence of difficult intubation, and decreased rate of first attempt
success utilizing DL 18. A recent randomized trial comparing the two positions during VL did not find a significant difference in intubation success rate with one position over the other 19.
Preoxygenation and Ventilation Strategies New literature highlighting the importance of preoxygenation as a vital step in airway management has brought traditional views of RSI without bag-mask ventilation (BMV) into question. In addition, due to the low physiologic reserve of the majority of ICU patients with an indication for endotracheal intubation, life threatening hypoxemia during the procedure is a major concern. In a recent US multicenter prospective trial, investigators randomized ICU patients to undergo either BMV or no ventilation between induction and laryngoscopy. Patients in the BMV group had higher oxygen saturations and a lower incidence of severe hypoxemia than those receiving no ventilation. Furthermore, though the study was not adequately powered to detect a difference in the rate of aspiration, the incidence of operator-reported aspiration was lower in the BMV group than in the no-ventilation group. Unless the patient is estimated to be at the highest risk of aspiration, an airway instrumentation strategy including BMV prior to EI while carefully monitoring the pressure delivered during mask ventilation so as not to insufflate the stomach appears reasonable 20.
Other modalities for preoxygenation include non-invasive positive pressure ventilation (NIPPV) and high flow nasal cannula (HFNC). The combination of NIPPV and HFNC appears better than NIPPV alone in preventing desaturation during intubation 21, and is more effective than BMV. By contrast, HFNC alone appears to be equivalent to standard BMV preoxygenation 22. A bedside score to predict hypoxia during intubation has been developed from data of 4
randomized controlled trials examining intubation in the ICU (Table 3) 23. Additionally, performing a recruitment maneuver may improve hypoxemia that develops after intubation 24.
Controversies in RSI The radiographic and clinical evidence based in support for cricoid pressure for RSI remains somewhat equivocal in light of an investigation using MRI studies that showed the hypopharynx (rather than the esophagus) is posterior to the cricoid ring 25 and cricoid pressure reliably compresses the hypopharynx. Nonetheless, a recent, double-blind, prospective non-inferiority trial demonstrated the lack of efficacy of cricoid pressure in preventing aspiration in patients at high risk for aspiration. Furthermore, there was evidence that it may worsen the quality of laryngeal exposure 26. One explanation for this observation may be that clinicians have difficulty identifying the cricoid ring using anatomic landmarks 27.
Pharmacology New information regarding optimal utilization and indications for the use of sedative hypnotic agents, neuromuscular blocker (NMB) agents, NMB antagonists, and vasopressors in the pharmacologic management of the ICU patient in the peri-intubation period continues to evolve. Decision making around optimal use of pharmacological adjuncts to facilitate EI has to be highly individualized with careful consideration of each patient’s situation and comorbidity profile, as well as the clinician’s familiarity with the drugs to be used. Commonly used drugs for EI are presented in Table 4 28. Propofol
Propofol is a popular hypnotic agent for patients undergoing elective and urgent airway management in the operating room due to its pleasant emergence and little residual effect, and the fact that it is readily titratable and has a rapid onset. In patients with cardiac comorbidities and limited physiologic reserve it can be associated with significant hypotension and bradycardia, thus limiting its use in the ICU patient population. Despite these concerns, it is an attractive alternative to other commonly used induction agents in the ICU as propofol provides superior conditions for endotracheal intubation without the use of muscle relaxants. Strategies to mitigate a predictable hypotensive response to propofol in critically ill patients include preemptive or concomitant treatment with vasopressor agents and judicious fluid loading in patients who have signs of hypovolemia. In a retrospective study of 472 consecutive patients undergoing urgent intubation in a medical ICU, the use of propofol appeared to be safe with low rates of hypotension (4%) when combined with a protocolized approach limiting the initial bolus dose of the drug to 0.5-1mg/kg. Vasopressor agents were immediately available and were utilized in 59% of cases for peri-intubation hemodynamic support 29. Similarly, in a retrospective comparison between etomidate and propofol to facilitate RSI in normotensive and hypertensive trauma patients, no statistically significant impact on hemodynamics was found when the dose of propofol was limited, and vasopressor therapy was immediately available for hemodynamic support 30. Other strategies aimed at mitigating the hypotensive side effects associated with propofol include the combination of ketamine and propofol (“ketofol”) which has been described in case series 31 and appears to be a safe alternative induction agent with non-superiority to reduced doses of etomidate for preservation of hemodynamics. 32.
Etomidate Etomidate as an induction agent has lost favor based on concerns for adrenal suppression; however, there remains clinical equipoise around the question of safety of etomidate to facilitate EI in critically ill patients with signs and symptoms of sepsis or septic shock. In one of the largest meta-analyses of mostly observational and retrospective data, single-dose etomidate did not increase mortality in patients with sepsis 33. These findings were corroborated in an analysis conducted by the Cochrane Group who found no conclusive evidence suggesting that etomidate increases mortality or healthcare utilization in the critically ill 34. If patients in septic shock receive etomidate, corticosteroid supplementation may be considered 35.
Ketamine Ketamine has gained increasing popularity as an induction agent to facilitate EI in the critically ill, due to its sympathomimetic properties from enhanced catecholamine activity resulting in a positive hemodynamic profile 36. When compared to etomidate for RSI in trauma patients, periintubation outcomes including first-pass success rates were similar between the two agents 37. In a prospective trial in 655 critically ill patients randomized to either etomidate or ketamine to facilitate RSI, the authors found no significant difference in intubating conditions, and no serious adverse events associated with either drug. There was however a significantly higher percentage of adrenal insufficiency found in the etomidate group 38. In the critically ill, catecholamine depleted patient, ketamine can act as a direct negative inotrope, and vigilance should be maintained.
Dexmedetomidine
The utility of dexmedetomidine as an adjunct for the management of the critically ill airway appears to be limited due to its slow onset, as well as the fact that bolus administration of the drug can result in significant side effects such as hypotension and bradycardia 39.
Neuromuscular Blocking Agents (NMBA) Over the past decade, critical care medicine has seen a shift of practice based on new evidence in support of NMBA for intubation of the critically ill. Based on prospective observational studies, the use of NMBA to facilitate intubation in the critically ill patient appears to increase first attempt intubation success rates without increasing complication rates 40,41. The availability of sugammadex, a drug that rapidly reverses the effects of the steroidal NBMAs, may render the use of rocuronium a more attractive option to optimize intubating conditions without the adverse side effects (e.g. hyperkalemia) associated with the use of succinylcholine. A recent Cochrane analysis found no difference in the quality of intubating conditions when succinylcholine was compared to rocuronium (0.9-1.2mg/kg dose) to facilitate EI 42.
Sugammadex Sugammadex is a modified γ-cyclodextrin that rapidly reverses the effects of the steroidal neuromuscular blockers rocuronium and vecuronium through formation of a stable, 1:1 complex, resulting in encapsulation (chelation) of the drug, thereby reducing the amount of free NMBA that is available to bind to nicotinic acetylcholine receptors at the neuromuscular junction. A comprehensive review of this reversal agent has been published 43 .
In a scenario of cannot intubate, cannot ventilate during emergent airway management in the ICU in a patient who has received an intubating dose of rocuronium or vecuronium, sugammadex administered at a dose of 16 mg/kg IV, allows for the reversal of deep neuromuscular block (defined as the time to recovery of the train-of-four ratio [TOF] to 0.9) within ~3min after administration. It is important to note that patients undergoing reversal of NMBA facilitated with rocuronium recovered significantly faster after administration of sugammadex, as compared to those recovering spontaneously after administration of succinylcholine42. This is of particular relevance in the context of an anticipated difficult intubation which thus far has favored the use of succinylcholine to facilitate RSI in critically ill patients due to its much shorter duration of action. Furthermore, in situations of deep neuromuscular blockade, acetylcholinesterase inhibitors would not be a therapeutic alternative for NMBA reversal. The dosing guidelines are 2 mg/kg for patients who have recovered two twitches on TOF stimulation and 4 mg/kg for those who have exhibited 1-2 post-tetanic counts (PTC).
In a general patient population, the use of sugammadex was associated with a 40% reduction in adverse events compared to neostigmine, particularly in the rate of bradycardia. While there is a paucity of safety data available in the literature regarding the use of sugammadex in critically ill patients, its use appears safe in patients with cardiac 44, pulmonary 45, and liver disease 46, as well as morbidly obese patients 47. Caution is recommended in patients with mild to moderate renal impairment as the drug is excreted unchanged in the kidneys. While the use of sugammadex is not recommended by the manufacturer in patients with severe renal impairment, the rocuroniumsugammadex complex can be removed using hemodialysis 48.
Hemodynamic Support of the Critically Ill Patient during Intubation Critically ill patients undergoing emergency airway management are at risk for peri-procedural hypotension, which can lead to cardiac arrest 6,49. While more prospective research is needed to validate optimal strategies for hemodynamic support in critically ill patients undergoing emergency airway management, having an individualized plan for the patient prior to intubation seems prudent. Two principal choices of pharmacological support have been described in the literature: bolus or push-dose vasopressors (PDP) 50 and continuous infusion of vasopressor agents either during, or immediately following intubation 15.
Choices of vasopressors for PDP therapy during ICU intubations include phenylephrine, ephedrine, norepinephrine and epinephrine Dosing strategies are presented in Table 5. Epinephrine and norepinephrine are more commonly used for continuous infusion. It is important to note that dilution of potent vasopressor agents indicated for continuous infusion such as epinephrine and norepinephrine can pose additional risk of medication error. Their use as bolus agents must be exercised with extreme caution by experienced providers.
Current Concepts in Tracheal Intubation in the ICU With the advancement in, and miniaturization of fiberoptic equipment, video laryngoscopes have become more affordable and more frequently utilized in the OR, ED and ICU and many practitioners have adopted a VL first approach to endotracheal intubation. A recently published practice survey of Australian and New Zealand ICUs revealed availability of VL was nearly universal but only 43% of respondents used it as a first line device 51. A 2014 review of
52
published randomized trials and observational studies comparing VL to DL found that VL
reduced the risk of difficult tracheal intubation, improved laryngeal visualization, and increased first-attempt success 53.
A comprehensive systematic review evaluating tracheal intubation in critically ill adults identified nine studies (seven published after 2014) comparing VL with traditional DL. While the settings, devices, and operators differ, the authors concluded that VL did not improve time to intubation or first attempt success rate. Furthermore, in post-hoc analyses of two of the nine trials the authors found evidence of a greater incidence of severe desaturation episodes and lifethreatening complications, as well as a higher mortality in the severe head injury subgroup associated with VL 24. These findings, paired with those of Cabrini et al, serve to provide a cautionary note regarding VL use in critically ill patients 24.
As with any procedure, operator experience has a profound effect on success, and additional studies are ongoing in different environments and with operators with different experience levels. Use of a bougie can improve first pass success52. In our practice, DL, VL and a bougie are readily available and choice of modality is at the discretion of the proceduralist. Additionally, we have equipment available for both VL or flexible fiberoptic intubation in the awake patient if the clinical scenario warrants this approach.
Human Factors According to the NAP-4 report, inadequate training and experience, nonadherence to guidelines, and failure to plan for failure were identified among the factors contributing to adverse
outcomes. Human factors were considered to have contributed to at least 40% of instances of adverse outcomes 5 and efforts to address human factors and team dynamics have been undertaken. There is some evidence that the use of cognitive aids, in simulation and real-life, may improve technical performance and team communication in crisis situations 54, although the quality of cognitive aids varies and further studies are needed. The Vortex Approach 55 is a system designed to support decision-making processes during crises in order to reduce cognitive load as airway interventions progress from failed mask-ventilation, LMA and intubation to pursuit of a surgical airway (Figure 1) 56,57. Simulation-based team training in management of the difficult airway has now been mandated by the Australian and New Zealand College of Anesthetists as a part of the continuing professional development.
A comprehensive system-wide program to address the safety and efficacy of difficult airway management has been developed by a multidisciplinary inter-professional team at the Johns Hopkins Hospital 58. The program focused on developing a response team, a standardized response process, monitoring of team activities and outcomes, and multispecialty team-based simulation training. A recently published 10-year experience of the program reported no airwayrelated deaths, no sentinel events, and no malpractice claims for adult patients 59.
Summary Despite advances in technology and the introduction of newer pharmacological agents, airway management in critically ill patient remains challenging and more research is required to determine optimal strategies. Quintard et al proposed an algorithm of the approach to the periintubation period that encompasses many of the concepts covered in this update (Figure 2) 60.
Our view on the utility of NMBAs to facilitate EI has evolved, and there is evidence to suggest that in the right patient, they can decrease complications associated with EI. ICU programs should invest in strategies around team building and the establishment of protocols and clinical practice guidelines to assist providers participating in EI. Available equipment, including fiberoptic technology to facilitate EI should be standardized, and robust training programs should be in place to optimize patient care and minimize the risk of complications. Access to high fidelity simulation programs is more ubiquitous, and crisis simulation can be a valuable tool in support of effective team training, and to maintain provider competency. Finally, clinical providers participating in EI are reminded that in order to prevent profound hypoxemia and associated irreversible end organ damage, the provision of adequate ventilation takes precedence over endotracheal intubation in order to maintain adequate oxygenation and ensure good patient outcomes.
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Gu WJ, Wang F, Tang L, Liu JC. Single-dose etomidate does not increase mortality in patients with sepsis: a systematic review and meta-analysis of randomized controlled trials and observational studies. Chest. 2015;147(2):335-346. Bruder EA, Ball IM, Ridi S, Pickett W, Hohl C. Single induction dose of etomidate versus other induction agents for endotracheal intubation in critically ill patients. Cochrane Database Syst Rev. 2015;1:CD010225. Jung B, Clavieras N, Nougaret S, et al. Effects of etomidate on complications related to intubation and on mortality in septic shock patients treated with hydrocortisone: a propensity score analysis. Crit Care. 2012;16(6):R224. White JM, Ryan CF. Pharmacological properties of ketamine. Drug Alcohol Rev. 1996;15(2):145-155. Upchurch CP, Grijalva CG, Russ S, et al. Comparison of Etomidate and Ketamine for Induction During Rapid Sequence Intubation of Adult Trauma Patients. Ann Emerg Med. 2017;69(1):24-33 e22. Jabre P, Combes X, Lapostolle F, et al. Etomidate versus ketamine for rapid sequence intubation in acutely ill patients: a multicentre randomised controlled trial. Lancet. 2009;374(9686):293-300. Piao G, Wu J. Systematic assessment of dexmedetomidine as an anesthetic agent: a metaanalysis of randomized controlled trials. Arch Med Sci. 2014;10(1):19-24. Wilcox SR, Bittner EA, Elmer J, et al. Neuromuscular blocking agent administration for emergent tracheal intubation is associated with decreased prevalence of procedure-related complications. Crit Care Med. 2012;40(6):1808-1813. Mosier JM, Sakles JC, Stolz U, et al. Neuromuscular blockade improves first-attempt success for intubation in the intensive care unit. A propensity matched analysis. Ann Am Thorac Soc. 2015;12(5):734-741. Hristovska AM, Duch P, Allingstrup M, Afshari A. Efficacy and safety of sugammadex versus neostigmine in reversing neuromuscular blockade in adults. Cochrane Database Syst Rev. 2017;8:CD012763. Keating GM. Sugammadex: A Review of Neuromuscular Blockade Reversal. Drugs. 2016;76(10):1041-1052. Dahl V, Pendeville PE, Hollmann MW, Heier T, Abels EA, Blobner M. Safety and efficacy of sugammadex for the reversal of rocuronium-induced neuromuscular blockade in cardiac patients undergoing noncardiac surgery. Eur J Anaesthesiol. 2009;26(10):874884. Amao R, Zornow MH, Cowan RM, Cheng DC, Morte JB, Allard MW. Use of sugammadex in patients with a history of pulmonary disease. J Clin Anesth. 2012;24(4):289-297. Fujita A, Ishibe N, Yoshihara T, et al. Rapid reversal of neuromuscular blockade by sugammadex after continuous infusion of rocuronium in patients with liver dysfunction undergoing hepatic surgery. Acta Anaesthesiol Taiwan. 2014;52(2):54-58. Carron M, Veronese S, Foletto M, Ori C. Sugammadex allows fast-track bariatric surgery. Obes Surg. 2013;23(10):1558-1563. Cammu G, Van Vlem B, van den Heuvel M, et al. Dialysability of sugammadex and its complex with rocuronium in intensive care patients with severe renal impairment. Br J Anaesth. 2012;109(3):382-390.
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Green RS, Turgeon AF, McIntyre LA, et al. Postintubation hypotension in intensive care unit patients: A multicenter cohort study. J Crit Care. 2015;30(5):1055-1060. Weingart S. Push-dose pressors for immediate blood pressure control. Clin Exp Emerg Med. 2015;2(2):131-132. Toolis M, Tiruvoipati R, Botha J, Green C, Subramaniam A. A practice survey of airway management in Australian and New Zealand intensive care units. Crit Care Resusc. 2019;21(2):139-147. Driver BE, Prekker ME, Klein LR, et al. Effect of Use of a Bougie vs Endotracheal Tube and Stylet on First-Attempt Intubation Success Among Patients With Difficult Airways Undergoing Emergency Intubation: A Randomized Clinical Trial. JAMA. 2018;319(21):2179-2189. De Jong A, Molinari N, Conseil M, et al. Video laryngoscopy versus direct laryngoscopy for orotracheal intubation in the intensive care unit: a systematic review and metaanalysis. Intensive Care Med. 2014;40(5):629-639. Marshall S. The use of cognitive aids during emergencies in anesthesia: a review of the literature. Anesth Analg. 2013;117(5):1162-1171. Chrimes N. The Vortex: a universal 'high-acuity implementation tool' for emergency airway management. Br J Anaesth. 2016;117 Suppl 1:i20-i27. Frerk C, Mitchell VS, McNarry AF, et al. Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults. Br J Anaesth. 2015;115(6):827-848. Chrimes N. The Vortex. 2013, 2016; VortexApproach.org. Copyright Nicholas Chrimes 2013, 2016. Licensed under Creative Commons Attribution-NonCommercialNoDerivatives 2014.2010 International License Available at: VortexApproach.org. Accessed 4/1/2019, 2019. Mark LJ, Herzer KR, Cover R, et al. Difficult airway response team: a novel quality improvement program for managing hospital-wide airway emergencies. Anesth Analg. 2015;121(1):127-139. Mark L, Lester L, Cover R, Herzer K. A Decade of Difficult Airway Response Team: Lessons Learned from a Hospital-Wide Difficult Airway Response Team Program. Crit Care Clin. 2018;34(2):239-251. Quintard H, l'Her E, Pottecher J, et al. Experts' guidelines of intubation and extubation of the ICU patient of French Society of Anaesthesia and Intensive Care Medicine (SFAR) and French-speaking Intensive Care Society (SRLF) : In collaboration with the pediatric Association of French-speaking Anaesthetists and Intensivists (ADARPEF), Frenchspeaking Group of Intensive Care and Paediatric emergencies (GFRUP) and Intensive Care physiotherapy society (SKR). Ann Intensive Care. 2019;9(1):13.
Predictors of Cardiovascular Collapse and Cardiac Arrest • Cardiovascular Collapse (CVC)* • Cardiac Arrest+ • Age > 60 • Indication for intubation = acute respiratory failure • First intubation • Noninvasive ventilation required for preoxygenation • Breathing less than 70% oxygen *defined as SBP ≤ 65 mmHg recorded at least once and/or ≤ 90 for ≥ 30 min despite vascular loading with 500-1000ml and/or introduction of vasoactive support
• • • • •
SBP < 90 mm Hg Hypoxemia No preoxygenation BMI > 25 Age > 75
+defined
as asystole, bradycardia, or ventricular dysrhythmia with nonmeasurable blood pressure during or within 5 minutes after intubation, requiring cardiopulmonary resuscitation
Table 1. Summary of predictors of factors associated with cardiovascular collapse (left column), and cardiac arrest (right column). Adapted from De Jong et al., and Perbet et al.
MACOCHA Factors and Scoring • Patient-Related Factors • • • •
Mallampati Score of III or IV Obstructive Sleep Apnea Reduced Cervical Spine Mobility Limited mouth opening < 3cm
Points Awarded 5 2 1 1
• Pathology-Related Factors • Coma • Severe Hypoxemia (<80%)
1 1
• Operator-Related Factors • Non-Anesthesologist Table 2. MACHOCHA Factors and Scoring. Adapted from De Jong et al.
1
Each positive factor is awarded the assigned point value for a point total from 0 to 12. 0 suggests easy; 12 suggests very difficult
AT RISK Score Factors and Scoring • Factors • • • •
Age < 50 Trainee-proceduralist with < 100 prior intubations Race other than black Indication for intubation is hypoxemic respiratory failure • SpO2 at induction < 94% • kg/m2 (BMI) > 35
Table 3. AT RISK Factors and Scoring. Adapted from McKown et al.
Points Awarded 1 1 1 1 1
1
Each positive factor is awarded the assigned point value for a point total from 0 to 6 to predict severe hypoxemia. 0 suggests low risk; 6 suggests high risk
Table 4. Properties of Medications Frequently used for Airway Management in the ICU. Abbreviations: AChR, acetylcholine receptor; CBF, cerebral blood flow; CMRO2, cerebral metabolic rate of oxygen; CNS, central nervous system; CV, cardiovascular; GABA, γ-aminobutyric acid receptor; HR, heart rate; ICP, intracranial pressure; MAP, mean arterial pressure; MOA, mechanism of action; NMB, neuromuscular blocker; NMDA, N-methyl-d-aspartate receptor; 0, no effect; , increase; , decrease. a evidence is sparse. Adapted from Watson NC and Heard SO. Comprehensive Critical Care: Adult. Mount Prospect, IL. Society of Critical Care Medicine; 2017. Copyright 2017 Society of Critical Care Medicine.
Push Dose Vasopressors in the ICU • Phenylephrine • Direct alpha adrenergic agonist • Standard concentration 10mg/250ml = 40mcg/ml or 10mg/100ml = 100mcg/ml • 40-200mcg IVPB q1-5 min
• Ephedrine • Indirect stimulation of adrenergic system via endogenous catecholamine release with alpha and beta activity • Standard concentration 50mg/10ml • 5-10mg IVPB q1-5 min
• Norepinephrine • Direct alpha and beta adrenergic agonist • Standard concentration 4mg/250ml = 16mcg/ml or 16mg/250ml = 64mcg/ml • 8-16mcg IVPB q1-5min
• Epinephrine • Direct alpha and beta adrenergic agonist • Standard concentrations: 1mg in 100ml = 10mcg/ml, 4mg/250ml = 16mcg/ml or 16mg/250ml = 64mcg/ml • 10-20mcg IVPB q 1-5 min
Table 5. Push Dose Vasopressors in the ICU; caution and knowledge of concentration of vasopressors is of utmost importance given the potential for medication administration errors with multiple common dilutions
Figure 1: Vortex Approach as a cognitive aid for Can’t Intubate, Can’t Oxygenate (CICO) scenarios. Proceduralists start at the 12:00 position with max 3 attempts to mask ventilate a patient. If unsuccessful, move counter-clockwise for max 3 attempts at supraglottic airway rescue, followed by max 3 attempts at endotracheal intubation. If unsuccessful, the final common pathway is performance of a surgical airway. From VortexApproach.org. Copyright Nicholas Chrimes 2013, 2016. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License
Figure 2: Algorithm for intubation. Reproduced with permission from Quintard et. Al. Ann. Intensive Care (2019) 9:13
S0012-3692(19)34193-5
DOI:
https://doi.org/10.1016/j.chest.2019.10.026
Reference:
CHEST 2703
To appear in:
CHEST
Received Date: 15 April 2019 Revised Date:
5 October 2019
Accepted Date: 9 October 2019
Please cite this article as: Scott JA, Heard SO, Zayaruzny M, Walz JM, Airway Management in Critical Illness: An Update, CHEST (2019), doi: https://doi.org/10.1016/j.chest.2019.10.026. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Copyright © 2019 Published by Elsevier Inc under license from the American College of Chest Physicians.
Airway Management in Critical Illness: An Update
J. Aaron Scott, DO; Stephen O. Heard, MD; Maksim Zayaruzny, MD MS-HPEd; J. Matthias Walz, MD
From the Department of Anesthesiology and Perioperative Medicine, Division of Critical Care Medicine UMass Memorial Medical Center, Worcester, MA
Correspondence:
J. Aaron Scott, DO Department of Anesthesiology UMass Memorial Medical Center 55 Lake Avenue North Worcester MA 01655
Abstract
Expertise in airway management is a vital skill for any provider caring for critically ill patients. A growing body of literature has identified the stark difference in peri-procedural outcomes of elective intubation in the operating room when compared to emergency intubation in the intensive care unit (ICU). A number of strategies to reduce the morbidity and mortality associated with airway management in the critically ill have been described. In this review, we will provide an updated framework for airway assessment before direct laryngoscopy (DL) and video laryngoscopy (VL), utilization of newer pharmacologic agents, comment on current concepts in tracheal intubation in the ICU, and address human factors around critical decisionmaking during ICU airway management.
Introduction Over the past decade, advances have been made towards decreasing the morbidity and mortality associated with airway management in critical illness. Since the publication of our last review article 1, the critical care community has seen broad adoption of video-laryngoscopy (VL), introduction of new pharmacological agents, and publication of high-quality research around protocol driven airway management. To provide this update and review of airway management in critical illness in adult patients we searched PubMed, Embase, Scopus, Google Scholar, the Cochrane Library (Cohrane Collaboration), and references of articles retrieved. Publications from 2007 through June of 2019 were then examined for relevancy and integrated. For a detailed list of search terms used please see Additional file 1. For the purpose of this review, we assume that the reader has basic knowledge of airway anatomy and is proficient in basic principles of airway management.
We will discuss the validation of the MACHOCHA score (Mallamapati class, presence of obstructive sleep Apnea OSA, Cervical spine mobility, mouth Opening, presence of Coma or Hypoxia, and presence of an Anesthesiologist) for airway assessment before DL, predictors of difficult VL, airway kit and checklist utilization, as well as patient positioning and adjunctive oxygen delivery device use. Additionally, we discuss the role of VL in the ICU, controversies around Rapid Sequence Intubation (RSI), and provide an updated summary on the most frequently used pharmacologic agents to facilitate ICU-intubation. Lastly, we review the relevant literature on human factors in airway management.
Morbidity and Mortality Associated with ICU Intubations
Expertise in airway management is a vital skill for any provider caring for critically ill patients. As compared to elective airway management in the operating room (OR), securing an airway in the ICU poses unique challenges and is associated with increased morbidity and mortality. In a one-year review of all National Health Service hospitals in the United Kingdom (UK), the 4th National Audit Project (NAP4) study examined major airway complications during anesthesia, including death, brain damage, emergency surgical airway and unanticipated ICU admission. The study found 46 events per million general anesthetics, or one in 22,000, and an associated mortality rate of 5.6 per million 2. Published data from the United States (US) show a mortality rate of 1.1 per million for patients undergoing general anesthetics 3.
A review of the literature examining airway management in the ICU paints a different picture. In 2004, Mort et al. identified that emergent intubation (EI) in remote locations, such as the ICU, resulted in a 1 in 50 rate of cardiac arrest 4. The predominant etiology of arrest in 83% of cases was hypoxemia, defined as any reduction in oxygen saturation (SpO2) < 90% if preoxygenated SpO2 was > 90%. Furthermore, in 63% of cases the hypoxemia was identified as being secondary to esophageal intubation.
These findings have been further supported by the second part of NAP4 where 25% of reported airway events occurred in the ICU and Emergency Department (ED) 5. Sixty-one percent of these events resulted in permanent patient harm or death: a 58-fold higher risk for emergent airway intervention in the ICU/ED as compared to elective airway management in the OR. Nearly 15 years after the publication of Mort, et al., De Jong et al. identified a rate of 1 in 40 cardiac arrests in ICU intubations that was associated with an increased risk of 28-day mortality
(hazard ratio = 3.9 [2.4-6.3]) 6. Factors predictive of peri-intubation cardiovascular collapse and cardiac arrest are presented in Table 1.
Airway Assessment Many commonly used methods for elective intubation are not feasible for ICU patients. According to one study, only 26 % of the patients requiring DL EI in the emergency department were able to cooperate with a Mallampati test 7. Another retrospective single center review of 838 patients documented that all of the RSI failures, and up to two thirds of non-cardiac arrest intubations, could not have undergone Mallampati scoring, neck mobility testing, or thyromental distance measurements 8. If assessible, inability to reach the lower incisors to the upper lip is a cautionary feature9.
More recently, a scoring methodology that combines anatomic, physiologic and operator characteristics was developed and validated in a multicenter study 10. The MACOCHA score uses a 12-point scale based on 7 independent predictors of difficult intubation with DL. Higher MACOCHA scores were associated with an increasing risk of difficult intubation. The investigators observed a sensitivity of 73%, specificity of 83%, a negative predictive value of 98%, and a positive predictive value of 36% (Table 2).
Despite the near ubiquitous presence of VL in the OR, ED and ICU, fewer data exist regarding predictors of difficult VL. DL failure is frequently associated with inability to visualize the glottis, whereas failure in VL is often related to inability to pass the endotracheal tube11. Airway
edema, blood in the airway, cervical immobility, obesity and small mouth opening have been associated with higher odds of first attempt failure 12,13.
Preparation for endotracheal intubation, Patient Positioning, and Rapid Sequence Intubation (RSI) Team approach and protocols Prior to airway instrumentation, conditions for intubation should be as close to ideal as possible. Several advances have been embraced from other areas of ICU care to become a part of optimal preparation for intubation. Following the broad adoption of the checklist to prevent central line associated bloodstream infections, other areas of medicine have utilized a similar approach to standardize processes and achieve improvements in patient safety and outcomes 14. Often high fidelity simulation is the entry arena used to familiarize trainees with new protocols. A kit or cart with all of the necessary supplies to facilitate invasive procedures is optimal to avoid the need for securing essential equipment at the last minute. In addition, some data suggest that a team approach with a defined intubation algorithm is beneficial in reducing complications related to EI 15-17.
Patient positioning The utility of the sniffing position for intubations outside of the operating room is unknown. A recent randomized trial of the “ramped” position (head of bed elevated 25 degrees, face parallel to the floor) vs “sniffing” position (torso supine, neck flexed, head extended) in critically ill adults with an average BMI of 27 found that a “ramped” position increased difficulty in laryngeal exposure, increased incidence of difficult intubation, and decreased rate of first attempt
success utilizing DL 18. A recent randomized trial comparing the two positions during VL did not find a significant difference in intubation success rate with one position over the other 19.
Preoxygenation and Ventilation Strategies New literature highlighting the importance of preoxygenation as a vital step in airway management has brought traditional views of RSI without bag-mask ventilation (BMV) into question. In addition, due to the low physiologic reserve of the majority of ICU patients with an indication for endotracheal intubation, life threatening hypoxemia during the procedure is a major concern. In a recent US multicenter prospective trial, investigators randomized ICU patients to undergo either BMV or no ventilation between induction and laryngoscopy. Patients in the BMV group had higher oxygen saturations and a lower incidence of severe hypoxemia than those receiving no ventilation. Furthermore, though the study was not adequately powered to detect a difference in the rate of aspiration, the incidence of operator-reported aspiration was lower in the BMV group than in the no-ventilation group. Unless the patient is estimated to be at the highest risk of aspiration, an airway instrumentation strategy including BMV prior to EI while carefully monitoring the pressure delivered during mask ventilation so as not to insufflate the stomach appears reasonable 20.
Other modalities for preoxygenation include non-invasive positive pressure ventilation (NIPPV) and high flow nasal cannula (HFNC). The combination of NIPPV and HFNC appears better than NIPPV alone in preventing desaturation during intubation 21, and is more effective than BMV. By contrast, HFNC alone appears to be equivalent to standard BMV preoxygenation 22. A bedside score to predict hypoxia during intubation has been developed from data of 4
randomized controlled trials examining intubation in the ICU (Table 3) 23. Additionally, performing a recruitment maneuver may improve hypoxemia that develops after intubation 24.
Controversies in RSI The radiographic and clinical evidence based in support for cricoid pressure for RSI remains somewhat equivocal in light of an investigation using MRI studies that showed the hypopharynx (rather than the esophagus) is posterior to the cricoid ring 25 and cricoid pressure reliably compresses the hypopharynx. Nonetheless, a recent, double-blind, prospective non-inferiority trial demonstrated the lack of efficacy of cricoid pressure in preventing aspiration in patients at high risk for aspiration. Furthermore, there was evidence that it may worsen the quality of laryngeal exposure 26. One explanation for this observation may be that clinicians have difficulty identifying the cricoid ring using anatomic landmarks 27.
Pharmacology New information regarding optimal utilization and indications for the use of sedative hypnotic agents, neuromuscular blocker (NMB) agents, NMB antagonists, and vasopressors in the pharmacologic management of the ICU patient in the peri-intubation period continues to evolve. Decision making around optimal use of pharmacological adjuncts to facilitate EI has to be highly individualized with careful consideration of each patient’s situation and comorbidity profile, as well as the clinician’s familiarity with the drugs to be used. Commonly used drugs for EI are presented in Table 4 28. Propofol
Propofol is a popular hypnotic agent for patients undergoing elective and urgent airway management in the operating room due to its pleasant emergence and little residual effect, and the fact that it is readily titratable and has a rapid onset. In patients with cardiac comorbidities and limited physiologic reserve it can be associated with significant hypotension and bradycardia, thus limiting its use in the ICU patient population. Despite these concerns, it is an attractive alternative to other commonly used induction agents in the ICU as propofol provides superior conditions for endotracheal intubation without the use of muscle relaxants. Strategies to mitigate a predictable hypotensive response to propofol in critically ill patients include preemptive or concomitant treatment with vasopressor agents and judicious fluid loading in patients who have signs of hypovolemia. In a retrospective study of 472 consecutive patients undergoing urgent intubation in a medical ICU, the use of propofol appeared to be safe with low rates of hypotension (4%) when combined with a protocolized approach limiting the initial bolus dose of the drug to 0.5-1mg/kg. Vasopressor agents were immediately available and were utilized in 59% of cases for peri-intubation hemodynamic support 29. Similarly, in a retrospective comparison between etomidate and propofol to facilitate RSI in normotensive and hypertensive trauma patients, no statistically significant impact on hemodynamics was found when the dose of propofol was limited, and vasopressor therapy was immediately available for hemodynamic support 30. Other strategies aimed at mitigating the hypotensive side effects associated with propofol include the combination of ketamine and propofol (“ketofol”) which has been described in case series 31 and appears to be a safe alternative induction agent with non-superiority to reduced doses of etomidate for preservation of hemodynamics. 32.
Etomidate Etomidate as an induction agent has lost favor based on concerns for adrenal suppression; however, there remains clinical equipoise around the question of safety of etomidate to facilitate EI in critically ill patients with signs and symptoms of sepsis or septic shock. In one of the largest meta-analyses of mostly observational and retrospective data, single-dose etomidate did not increase mortality in patients with sepsis 33. These findings were corroborated in an analysis conducted by the Cochrane Group who found no conclusive evidence suggesting that etomidate increases mortality or healthcare utilization in the critically ill 34. If patients in septic shock receive etomidate, corticosteroid supplementation may be considered 35.
Ketamine Ketamine has gained increasing popularity as an induction agent to facilitate EI in the critically ill, due to its sympathomimetic properties from enhanced catecholamine activity resulting in a positive hemodynamic profile 36. When compared to etomidate for RSI in trauma patients, periintubation outcomes including first-pass success rates were similar between the two agents 37. In a prospective trial in 655 critically ill patients randomized to either etomidate or ketamine to facilitate RSI, the authors found no significant difference in intubating conditions, and no serious adverse events associated with either drug. There was however a significantly higher percentage of adrenal insufficiency found in the etomidate group 38. In the critically ill, catecholamine depleted patient, ketamine can act as a direct negative inotrope, and vigilance should be maintained.
Dexmedetomidine
The utility of dexmedetomidine as an adjunct for the management of the critically ill airway appears to be limited due to its slow onset, as well as the fact that bolus administration of the drug can result in significant side effects such as hypotension and bradycardia 39.
Neuromuscular Blocking Agents (NMBA) Over the past decade, critical care medicine has seen a shift of practice based on new evidence in support of NMBA for intubation of the critically ill. Based on prospective observational studies, the use of NMBA to facilitate intubation in the critically ill patient appears to increase first attempt intubation success rates without increasing complication rates 40,41. The availability of sugammadex, a drug that rapidly reverses the effects of the steroidal NBMAs, may render the use of rocuronium a more attractive option to optimize intubating conditions without the adverse side effects (e.g. hyperkalemia) associated with the use of succinylcholine. A recent Cochrane analysis found no difference in the quality of intubating conditions when succinylcholine was compared to rocuronium (0.9-1.2mg/kg dose) to facilitate EI 42.
Sugammadex Sugammadex is a modified γ-cyclodextrin that rapidly reverses the effects of the steroidal neuromuscular blockers rocuronium and vecuronium through formation of a stable, 1:1 complex, resulting in encapsulation (chelation) of the drug, thereby reducing the amount of free NMBA that is available to bind to nicotinic acetylcholine receptors at the neuromuscular junction. A comprehensive review of this reversal agent has been published 43 .
In a scenario of cannot intubate, cannot ventilate during emergent airway management in the ICU in a patient who has received an intubating dose of rocuronium or vecuronium, sugammadex administered at a dose of 16 mg/kg IV, allows for the reversal of deep neuromuscular block (defined as the time to recovery of the train-of-four ratio [TOF] to 0.9) within ~3min after administration. It is important to note that patients undergoing reversal of NMBA facilitated with rocuronium recovered significantly faster after administration of sugammadex, as compared to those recovering spontaneously after administration of succinylcholine42. This is of particular relevance in the context of an anticipated difficult intubation which thus far has favored the use of succinylcholine to facilitate RSI in critically ill patients due to its much shorter duration of action. Furthermore, in situations of deep neuromuscular blockade, acetylcholinesterase inhibitors would not be a therapeutic alternative for NMBA reversal. The dosing guidelines are 2 mg/kg for patients who have recovered two twitches on TOF stimulation and 4 mg/kg for those who have exhibited 1-2 post-tetanic counts (PTC).
In a general patient population, the use of sugammadex was associated with a 40% reduction in adverse events compared to neostigmine, particularly in the rate of bradycardia. While there is a paucity of safety data available in the literature regarding the use of sugammadex in critically ill patients, its use appears safe in patients with cardiac 44, pulmonary 45, and liver disease 46, as well as morbidly obese patients 47. Caution is recommended in patients with mild to moderate renal impairment as the drug is excreted unchanged in the kidneys. While the use of sugammadex is not recommended by the manufacturer in patients with severe renal impairment, the rocuroniumsugammadex complex can be removed using hemodialysis 48.
Hemodynamic Support of the Critically Ill Patient during Intubation Critically ill patients undergoing emergency airway management are at risk for peri-procedural hypotension, which can lead to cardiac arrest 6,49. While more prospective research is needed to validate optimal strategies for hemodynamic support in critically ill patients undergoing emergency airway management, having an individualized plan for the patient prior to intubation seems prudent. Two principal choices of pharmacological support have been described in the literature: bolus or push-dose vasopressors (PDP) 50 and continuous infusion of vasopressor agents either during, or immediately following intubation 15.
Choices of vasopressors for PDP therapy during ICU intubations include phenylephrine, ephedrine, norepinephrine and epinephrine Dosing strategies are presented in Table 5. Epinephrine and norepinephrine are more commonly used for continuous infusion. It is important to note that dilution of potent vasopressor agents indicated for continuous infusion such as epinephrine and norepinephrine can pose additional risk of medication error. Their use as bolus agents must be exercised with extreme caution by experienced providers.
Current Concepts in Tracheal Intubation in the ICU With the advancement in, and miniaturization of fiberoptic equipment, video laryngoscopes have become more affordable and more frequently utilized in the OR, ED and ICU and many practitioners have adopted a VL first approach to endotracheal intubation. A recently published practice survey of Australian and New Zealand ICUs revealed availability of VL was nearly universal but only 43% of respondents used it as a first line device 51. A 2014 review of
52
published randomized trials and observational studies comparing VL to DL found that VL
reduced the risk of difficult tracheal intubation, improved laryngeal visualization, and increased first-attempt success 53.
A comprehensive systematic review evaluating tracheal intubation in critically ill adults identified nine studies (seven published after 2014) comparing VL with traditional DL. While the settings, devices, and operators differ, the authors concluded that VL did not improve time to intubation or first attempt success rate. Furthermore, in post-hoc analyses of two of the nine trials the authors found evidence of a greater incidence of severe desaturation episodes and lifethreatening complications, as well as a higher mortality in the severe head injury subgroup associated with VL 24. These findings, paired with those of Cabrini et al, serve to provide a cautionary note regarding VL use in critically ill patients 24.
As with any procedure, operator experience has a profound effect on success, and additional studies are ongoing in different environments and with operators with different experience levels. Use of a bougie can improve first pass success52. In our practice, DL, VL and a bougie are readily available and choice of modality is at the discretion of the proceduralist. Additionally, we have equipment available for both VL or flexible fiberoptic intubation in the awake patient if the clinical scenario warrants this approach.
Human Factors According to the NAP-4 report, inadequate training and experience, nonadherence to guidelines, and failure to plan for failure were identified among the factors contributing to adverse
outcomes. Human factors were considered to have contributed to at least 40% of instances of adverse outcomes 5 and efforts to address human factors and team dynamics have been undertaken. There is some evidence that the use of cognitive aids, in simulation and real-life, may improve technical performance and team communication in crisis situations 54, although the quality of cognitive aids varies and further studies are needed. The Vortex Approach 55 is a system designed to support decision-making processes during crises in order to reduce cognitive load as airway interventions progress from failed mask-ventilation, LMA and intubation to pursuit of a surgical airway (Figure 1) 56,57. Simulation-based team training in management of the difficult airway has now been mandated by the Australian and New Zealand College of Anesthetists as a part of the continuing professional development.
A comprehensive system-wide program to address the safety and efficacy of difficult airway management has been developed by a multidisciplinary inter-professional team at the Johns Hopkins Hospital 58. The program focused on developing a response team, a standardized response process, monitoring of team activities and outcomes, and multispecialty team-based simulation training. A recently published 10-year experience of the program reported no airwayrelated deaths, no sentinel events, and no malpractice claims for adult patients 59.
Summary Despite advances in technology and the introduction of newer pharmacological agents, airway management in critically ill patient remains challenging and more research is required to determine optimal strategies. Quintard et al proposed an algorithm of the approach to the periintubation period that encompasses many of the concepts covered in this update (Figure 2) 60.
Our view on the utility of NMBAs to facilitate EI has evolved, and there is evidence to suggest that in the right patient, they can decrease complications associated with EI. ICU programs should invest in strategies around team building and the establishment of protocols and clinical practice guidelines to assist providers participating in EI. Available equipment, including fiberoptic technology to facilitate EI should be standardized, and robust training programs should be in place to optimize patient care and minimize the risk of complications. Access to high fidelity simulation programs is more ubiquitous, and crisis simulation can be a valuable tool in support of effective team training, and to maintain provider competency. Finally, clinical providers participating in EI are reminded that in order to prevent profound hypoxemia and associated irreversible end organ damage, the provision of adequate ventilation takes precedence over endotracheal intubation in order to maintain adequate oxygenation and ensure good patient outcomes.
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Predictors of Cardiovascular Collapse and Cardiac Arrest • Cardiovascular Collapse (CVC)* • Cardiac Arrest+ • Age > 60 • Indication for intubation = acute respiratory failure • First intubation • Noninvasive ventilation required for preoxygenation • Breathing less than 70% oxygen *defined as SBP ≤ 65 mmHg recorded at least once and/or ≤ 90 for ≥ 30 min despite vascular loading with 500-1000ml and/or introduction of vasoactive support
• • • • •
SBP < 90 mm Hg Hypoxemia No preoxygenation BMI > 25 Age > 75
+defined
as asystole, bradycardia, or ventricular dysrhythmia with nonmeasurable blood pressure during or within 5 minutes after intubation, requiring cardiopulmonary resuscitation
Table 1. Summary of predictors of factors associated with cardiovascular collapse (left column), and cardiac arrest (right column). Adapted from De Jong et al., and Perbet et al.
MACOCHA Factors and Scoring • Patient-Related Factors • • • •
Mallampati Score of III or IV Obstructive Sleep Apnea Reduced Cervical Spine Mobility Limited mouth opening < 3cm
Points Awarded 5 2 1 1
• Pathology-Related Factors • Coma • Severe Hypoxemia (<80%)
1 1
• Operator-Related Factors • Non-Anesthesologist Table 2. MACHOCHA Factors and Scoring. Adapted from De Jong et al.
1
Each positive factor is awarded the assigned point value for a point total from 0 to 12. 0 suggests easy; 12 suggests very difficult
AT RISK Score Factors and Scoring • Factors • • • •
Age < 50 Trainee-proceduralist with < 100 prior intubations Race other than black Indication for intubation is hypoxemic respiratory failure • SpO2 at induction < 94% • kg/m2 (BMI) > 35
Table 3. AT RISK Factors and Scoring. Adapted from McKown et al.
Points Awarded 1 1 1 1 1
1
Each positive factor is awarded the assigned point value for a point total from 0 to 6 to predict severe hypoxemia. 0 suggests low risk; 6 suggests high risk
Table 4. Properties of Medications Frequently used for Airway Management in the ICU. Abbreviations: AChR, acetylcholine receptor; CBF, cerebral blood flow; CMRO2, cerebral metabolic rate of oxygen; CNS, central nervous system; CV, cardiovascular; GABA, γ-aminobutyric acid receptor; HR, heart rate; ICP, intracranial pressure; MAP, mean arterial pressure; MOA, mechanism of action; NMB, neuromuscular blocker; NMDA, N-methyl-d-aspartate receptor; 0, no effect; , increase; , decrease. a evidence is sparse. Adapted from Watson NC and Heard SO. Comprehensive Critical Care: Adult. Mount Prospect, IL. Society of Critical Care Medicine; 2017. Copyright 2017 Society of Critical Care Medicine.
Push Dose Vasopressors in the ICU • Phenylephrine • Direct alpha adrenergic agonist • Standard concentration 10mg/250ml = 40mcg/ml or 10mg/100ml = 100mcg/ml • 40-200mcg IVPB q1-5 min
• Ephedrine • Indirect stimulation of adrenergic system via endogenous catecholamine release with alpha and beta activity • Standard concentration 50mg/10ml • 5-10mg IVPB q1-5 min
• Norepinephrine • Direct alpha and beta adrenergic agonist • Standard concentration 4mg/250ml = 16mcg/ml or 16mg/250ml = 64mcg/ml • 8-16mcg IVPB q1-5min
• Epinephrine • Direct alpha and beta adrenergic agonist • Standard concentrations: 1mg in 100ml = 10mcg/ml, 4mg/250ml = 16mcg/ml or 16mg/250ml = 64mcg/ml • 10-20mcg IVPB q 1-5 min
Table 5. Push Dose Vasopressors in the ICU; caution and knowledge of concentration of vasopressors is of utmost importance given the potential for medication administration errors with multiple common dilutions
Figure 1: Vortex Approach as a cognitive aid for Can’t Intubate, Can’t Oxygenate (CICO) scenarios. Proceduralists start at the 12:00 position with max 3 attempts to mask ventilate a patient. If unsuccessful, move counter-clockwise for max 3 attempts at supraglottic airway rescue, followed by max 3 attempts at endotracheal intubation. If unsuccessful, the final common pathway is performance of a surgical airway. From VortexApproach.org. Copyright Nicholas Chrimes 2013, 2016. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License
Figure 2: Algorithm for intubation. Reproduced with permission from Quintard et. Al. Ann. Intensive Care (2019) 9:13