Airway management is a complex process that, if not performed in a proper and timely manner, may result in significant morbidity or mortality. The risk of intubation failure and associated adverse events is higher in critically ill patients due to differences in patient condition, environment, and practitioner experience. Even when controlling for provider experience, intubating conditions are worse and success rates are lower in the ICU compared with the controlled environment of the operating room (Taboada, et al. Anesthesiology. 2018;129[2]:321). Furthermore, the risk of injury and adverse events increases with the number of intubation attempts during an emergency (Sakles JC, et al. Acad Emerg Med. 2013;20[1]:71). Unfortunately, the paucity of high-grade evidence leads practitioners to rely on practice patterns developed during training and predicated on common sense airway management principles. The difficulty in evaluating airway management in the critically ill lies in the multi-step and complex nature of the process, including the pre-intubation, intubation, and post-intubation activities (Fig 1). Several recent publications have the potential to change airway management practice in the ICU. We will address the latest information on preoxygenation, use of neuromuscular blockade (NMB), and checklists in this setting.
Dr. Arthur J. Tokarczyk
Preoxygenation: Overrated?
Rapid-sequence intubation (RSI) is a technique intended to minimize the time from induction to intubation and reduce the risk of aspiration by primarily avoiding ventilation. The avoidance of bag-mask ventilation during this apneic period is common, due to concerns that positive pressure can produce gastric insufflation and regurgitation that may lead to aspiration. To attenuate the risk for critical desaturation, preoxygenation is classically provided prior to induction of anesthesia in the operative procedural areas. Although the benefit can be seen in patients undergoing elective intubation, critically ill patients often have difficulty in significantly raising the blood oxygen content despite preoxygenation with 100% oxygen delivered via face mask. As a result, the oxygen saturation can drop precipitously during the process of ICU intubation, especially if multiple or prolonged intubation attempts are required. These factors all contribute to the risk of hypoxemia and cardiac arrest during ICU intubations (De Jong A, et al. Crit Care Med. 2018;46[4]:532), which has led to the debate about the avoidance of ventilation during RSI in the critically ill. Recently, Casey and colleagues (Casey JD, et al. N Engl J Med. 2019;380[9]:811) evaluated the use of bag-mask ventilation (BMV) during RSI. In this ICU study, intubations were randomized to either include BMV or no ventilation after induction. The results suggested that the frequency of critical desaturation was lower in the patients receiving BMV after induction without a concomitant increase in frequency of aspiration. Although not powered to evaluate the difference in the incidence of aspiration, this study supports the use of BMV during the apneic phase of intubation, thereby decreasing the risk for critical desaturation.
Dr. Steven B. Greenberg
Neuromuscular blockade: Yes or no?
Awake intubation, with or without sedation, is often employed for managing the airway in high-risk patients. This technique allows the patient to maintain spontaneous ventilation in the event of repeated intubation attempts and has a lower hypotension risk. However, many critically ill patients cannot be managed in this manner due to lack of patient cooperation, emergent airway management requirements, or practitioner inexperience with this technique. As a result, many of these patients will require an induction agent, and concomitant administration of a neuromuscular blocking agent (NMB) to optimize intubating conditions. However, the avoidance of NMBs in emergent airway scenarios was not uncommon among attending physicians and trainees (Schmidt UH, et al. Anesthesiology. 2008;109[6]:973). The American College of Chest Physicians (CHEST) Difficult Airway Course faculty also recommended to not use NMB because of the high risk of failure to ventilate/oxygenate. Without NMB, the patient might be allowed to recover to spontaneous ventilation. This approach is taken in the American Society of Anesthesiologists Practice Guidelines for the Management of the Difficult Airway but is not necessarily applicable to the critically ill patient (Apfelbaum JL, et al. Anesthesiology. 2013;118[2]:251-70). In the event of “can’t intubate, can’t oxygenate” (CICO), the critically ill patient in extremis may not tolerate an attempt to return to spontaneous ventilation because spontaneous ventilation may have been initially inadequate.