The Cheese - Managing the Physiologically Difficult Airway

Managing the physiologically difficult airway is one of the highest acuity and highest stress challenges in the Emergency Department (ED) setting. Here, inspired by the Mosier et al. and Jabaley articles referenced below, we will discuss pre-oxygenation with non-invasive ventilation (1,2).

Mosier et al. and Jabaley discuss techniques to help optimize intubation and first-pass success in difficult physiologic situations such as hypoxia, hypotension, profound metabolic acidosis, and right ventricular failure. Non-invasive ventilation (NIV), and more specifically non-invasive positive-pressure ventilation (NIPPV), is recommended as an adjunct for pre-oxygenation in these critically ill patients to limit oxygen desaturations, peri-intubation cardiopulmonary arrests, and multi-organ dysfunction after intubation. How do the data suggest we incorporate these practices into the ED setting?

The Data

  • A study by Baillard et al. performed in the intensive care unit (ICU) was a prospective randomized study. Age, disease severity, and admission diagnosis were matched across the groups. One group received pre-oxygenation with non-rebreather (NRB) mask (n =26). The second group was pre-oxygenated using a mask attached to a ventilator in pressure support ventilation (PSV) mode with a target tidal volume (TV) of 7-10ml/kg, 100% FiO2, and positive end-expiratory pressure (PEEP) of 5 (n=27). The primary outcome was mean drop in oxygen saturation. Results showed more profound desaturations in the NRB group, with no statistically significant difference in post-intubation infiltrates on x-ray concerning for aspiration (3).

  • Several studies from the Anesthesia literature examined the effects of pre-oxygenating morbidly obese patients who may be more difficult to ventilate. Gander et al. was a single-blinded randomized control trial (RCT) evaluating 30 patients with body mass index (BMI) >35 undergoing intubation for elective surgery (4). The intervention group received 10 mmHg of pressure support (PS) via continuous positive airway pressure (CPAP) compared to the control group, which breathed through the CPAP mask without any pressure support. The NIPPV group had superior oxygenation throughout. Two other RCTs were similarly designed to evaluated obese patients pre-oxygenated in the operating room (OR) with outcomes showing superior oxygenation in patients who were pre-oxygenated with NIPPV (5,6).

  • Another trial examined a slightly different topic, looking at apneic oxygenation with high-flow nasal cannula (HFNC). The RCT, which was completed in the ICU setting, examined NIV alone versus NIV with HFNC for pre-oxygenation and apneic oxygenation in hypoxic patients requiring intubation (7). 25 patients received NIV (PS=10, PEEP=5, FiO2=100%) and then HFNC during intubation at 60 L/min with FiO2 100%. 24 patients received NIV alone with no apneic oxygenation via HFNC. The HFNC group had significantly higher O2 nadirs than the control group. Therefore, HFNC is a reasonable option for optimization during the apnea phase of intubation.

Limitations

While these studies are generally well designed, none take place in the ED setting, so it is challenging to translate their results to management of most critically ill patients in the ED. There are reasonable concerns in the ED setting about how patients would tolerate a NIV mask prior to intubation, specifically whether the risks of aspiration are higher and whether patients (who are more commonly experiencing altered mental status) would cooperate with NIV techniques. The Mosier et al. article notes that typical contraindications to NIV (altered mentation, delirium, risk of aspiration) may not apply in the acute ED circumstance, as a physician is present throughout the entirety of the intubation and the procedural duration is short. However, practically, such intubations with pre-oxygenation require strict and close coordination with respiratory therapy (RT) specialists and adequate resuscitation space, which may be challenging depending on the staffing and physical confines of a given ED. Lastly, many of the studies highlighted above were small in scale with relatively few participants and in settings different from the ED (namely, ICUs and ORs), which may not generalize to the ED population.

Strengths 

The review articles repeatedly emphasize that NIV may improve peri- and post-intubation outcomes, especially when facing specific and challenging pathology such as obesity and shunt physiology. Thus, using NIV as an adjunct to intubation is a strategy that may allow emergency physicians to better optimize sick patients at high risk of decompensating in the post-intubation period. For instance, patients requiring intubation who are experiencing pulmonary edema and a COPD exacerbation, which are both physiologically challenging conditions, would likely benefit. In patients with the right pathology, with time to spare for optimization and proper coordination of NIV, NIV may help prevent poor outcomes related to peri- and post-intubation hypoxia.

Takeaways

NIV pre-oxygenation may not yet be ready to be considered the standard of care within many ED settings. However, in the correct setting with time to spare, optimizing your patients for intubation with NIV may have significant benefits for your patients, especially when facing certain physiologically challenging pathologies (profound hypoxia, obesity, pulmonary edema, acidosis, etc.).

Authored by Kathryn McGregor, MD; Taylor Wahrenbrock, MD; and Eric Leser, MD.

References:

  1. Mosier JM, Joshi R, Hypes C, Pacheco G, Valenzuela T, Sakles JC. The Physiologically Difficult Airway. West J Emerg Med. 2015 Dec;16(7):1109-17. doi: 10.5811/westjem.2015.8.27467. Epub 2015 Dec 8. PMID: 26759664; PMCID: PMC4703154. 

  2. Jabaley, C.S. Managing the Physiologically Difficult Airway in Critically Ill Adults. Crit Care 27, 91 (2023). https://doi.org/10.1186/s13054-023-04371-3 

  3. Baillard C, Fosse JP, Sebbane M, Chanques G, Vincent F, Courouble P, Cohen Y, Eledjam JJ, Adnet F, Jaber S. Noninvasive ventilation improves preoxygenation before intubation of hypoxic patients. Am J Respir Crit Care Med. 2006 Jul 15;174(2):171-7. doi: 10.1164/rccm.200509-1507OC. Epub 2006 Apr 20. PMID: 16627862. 

  4. Gander S, Frascarolo P, Suter M, et al. Positive end-expiratory pressure during induction of general anesthesia increases duration of nonhypoxic apnea in morbidly obese patients. Anesth Analg. 2005;100:580–4. doi: 10.1213/01.ANE.0000143339.40385.1B. 

  5. Futier E, Constantin JM, Pelosi P, Chanques G, Massone A, Petit A, Kwiatkowski F, Bazin JE, Jaber S (2011) Noninvasive ventilation and alveolar recruitment maneuver improve respiratory function during and after intubation of morbidly obese patients: a randomized controlled study. Anesthesiology 114:1354–1363  

  6. Delay JM, Sebbane M, Jung B, Nocca D, Verzilli D, Pouzeratte Y, Kamel ME, Fabre JM, Eledjam JJ, Jaber S (2008) The effectiveness of noninvasive positive pressure ventilation to enhance preoxygenation in morbidly obese patients: a randomized controlled study. Anesth Analg 107:1707–1713 

  7. Jaber S, Monnin M, Girard M, Conseil M, Cisse M, Carr J, Mahul M, Delay JM, Belafia F, Chanques G, Molinari N, De Jong A. Apnoeic oxygenation via high-flow nasal cannula oxygen combined with non-invasive ventilation preoxygenation for intubation in hypoxaemic patients in the intensive care unit: the single-centre, blinded, randomised controlled OPTINIV trial. Intensive Care Med. 2016 Dec;42(12):1877-1887. doi: 10.1007/s00134-016-4588-9. Epub 2016 Oct 11. PMID: 27730283.