The Physiologically Difficult Airway

RCEM CPD in London this week and I am off to give a talk on this interesting and ever developing topic. Hope to see some of you there. Although I am not really allowed to reproduce the content, I thought it might be helpful to provide quick links to the evidence, guidelines and resources used within the talk. Please do share or advise in the comments if you have additional resources or golden nuggets of advice on this ever challenging issue.

This topic also links in with our previous blog post supporting a recent Difficult Airway Society presentation – worth a revisit if you have time.

Thanks all, Dan.

Overview articles on the physiologically difficult airway:

Mosier et al. The physiologically difficult airway. West J Emerg Med. 2015 Dec; 16(7): 1109–1117.

Mosier JM. Physiologically difficult airway in critically ill patients: winning the race between haemoglobin desaturation and tracheal intubation. BJA 2020; 125: E1-4.

Jabaley, C.S. Managing the Physiologically Difficult Airway in Critically Ill AdultsCrit Care 2023; 27:91

Russotto et al. Intubation Practices and Adverse Peri-intubation Events in Critically Ill Patients From 29 CountriesJAMA. 2021;325(12):1164–1172. doi:10.1001/jama.2021.1727

Bellolio et al. Incidence of Adverse Events in Adults Undergoing Procedural Sedation in the Emergency Department: A Systematic Review and Meta-analysis. Acad Emerg Med. 2016 Feb;23(2):119-34.

POCUS in the context of undiagnosed shock or during emergency airway management:

Stickles et al. The diagnostic accuracy of a point-of-care ultrasound protocol for shock etiology: A systematic review and meta-analysis. CJEM. 2019 May;21(3):406-417.

Khorsand et al. Role of Point-of-Care Ultrasound in Emergency Airway Management Outside the Operating Room. Anesthesia & Analgesia 2023 Online first

Relevant Evidence on Preventing CVS collapse:

Janz DR et al. Effect of a fluid bolus on cardiovascular collapse among critically ill adults undergoing tracheal intubation (PrePARE): a randomised controlled trial. Lancet Respir Med. 2019 Dec;7(12):1039-1047.

Russell DW. Effect of Fluid Bolus Administration on Cardiovascular Collapse Among Critically Ill Patients Undergoing Tracheal Intubation: A Randomized Clinical Trial. JAMA.2022;328(3):270–279

Heffner AC. Incidence and factors associated with cardiac arrest complicating emergency airway management. Resuscitation. 2013 Nov;84(11):1500-4.

Ferguson I et al. Fentanyl versus placebo with ketamine and rocuronium for patients undergoing rapid sequence intubation in the emergency department: The FAKT study-A randomized clinical trial. Acad Emerg Med. 2022 Jun;29(6):719-728.

Matchett G et al. Etomidate versus ketamine for emergency endotracheal intubation: a randomized clinical trial. Intensive Care Med. 2022;48:78–91.

Intensive Care Society. Vasopressor agents in the Adult ICU. 2020.

Relevant Evidence on Preventing Critical Hypoxaemia:

Driver et al. Flush Rate Oxygen for Emergency Airway Preoxygenation. Ann Emerg Med. 2017 Jan;69(1):1-6

Arora et al. Delivery of oxygen by standard oxygen flowmeters. Anaesthesia. 2021 Nov;76(11):1546-1547

Weingart SD et al. Delayed sequence intubation: a prospective observational study. Ann Emerg Med. 2015; 65: 349-55.

Oliveira et al. Advantages of Delayed Sequence Intubation in Selected Patients With COVID-19Anesth Analg. 2020; 131: e133-e4.

Casey JD et al. Bag-Mask Ventilation during Tracheal Intubation of Critically Ill Adults. N Engl J Med. 2019; 380: 811-21.

Sud A, Patel A. THRIVE: five years on and into the COVID-19 era. Br J Anaesth. 2021; 126: 768-73.

Guitton C et al. Nasal high-flow preoxygenation for endotracheal intubation in the critically ill patient: a randomized clinical trial. Intensive Care Med. 2019; 45: 447-58.

Semler MW et al. Randomized Trial of Apneic Oxygenation during Endotracheal Intubation of the Critically IllAm J Respir Crit Care Med. 2016; 193: 273-80.

Binks et al. Apneic oxygenation during intubation in the emergency department and during retrieval: A systematic review and meta-analysisAm J Emerg Med. 2017; 35: 1542-6.

Chiang et al. Non-invasive ventilation for preoxygenation before general anesthesia: a systematic review and meta-analysis of randomized controlled trials. BMC Anesthesiol. 2022 Sep 30;22(1):306

Relevant Evidence on Checklists:

Hardy & Horner. BET 2: Should real resuscitationists use airway checklists? Emerg Med J. 2016; 33: 439-41.

Turner JS, Bucca AW, Propst SL, Ellender TJ, Sarmiento EJ, Menard LM, Hunter BR. Association of Checklist Use in Endotracheal Intubation With Clinically Important Outcomes: A Systematic Review and Meta-analysisJAMA Netw Open. 2020; 3: e209278.

Guideline articles:

Higgs et al. Guidelines for the management of tracheal intubation in critically ill adults. BJA 2018; 120: 323-352.

Kornas RL et al. Society for Airway Management’s Special Projects Committee. Evaluation and Management of the Physiologically Difficult Airway: Consensus Recommendations From Society for Airway Management. Anesth Analg. 2021 Feb 1;132(2):395-405

How to make friends, influence people and implement change in airway management outside the operating room:

Horner D et al. 292 Emergency airway management outside the operating room; a three year prospective service evaluation and quality improvement projectEmergency Medicine Journal. 2020; 37: 836-7.

Bristol Airway Registry – [email protected]

Australia and New Zealand Emergency Department Airway Registry

National Emergency Airway Registry (USA)

Cite this article as: Dan Horner, "The Physiologically Difficult Airway," in St.Emlyn's, April 17, 2023,

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