Airway Management in Critical Illness: Rescue Strategies

esophageal obturator airwayShould initial attempts at endotracheal intubation fail, an alternative strategy for providing ventilation to the patient, and ultimately for securing the airway, must be in place. The implementation of the ASA DAA in the critical care setting is logical and, according to one analysis, may have decreased the number of failed airways in the ICU environment. Since this airway algorithm was originally developed as a tool for anesthesia providers in the operating room, some minor adaptations for the ICU setting should be considered (Fig 2). While assessments of the likelihood of successful intubation and the clinical impact of basic management problems remain the same, critically ill patients in respiratory failure will almost certainly have less tolerance for periods of apnea than patients with unanticipated difficult airways in the operating room. The return to spontaneous ventilation is an important exit strategy for intubation in the operating room during elective surgery. In the ICU, this is often impossible due to mechanical failure and the limited physiologic reserves of the patient. Strategies for airway management in the emergency pathway of the ASA DAA include alternative means to provide ventilation (eg, the LMA-Fasttrach described in the previous section, as well as the Combitube; Tyco-Healthcare-Kendall USA; Mansfield, MA). The LmA can also be used as an intubation conduit and has been reported as a successful bridge to percutaneous tracheostomy in a case of failed airway in the ICU. The Combitube combines the features of an ETT and an esophageal obturator airway, and reduces the risk of aspiration. The use of these devices can be learned easily by personnel who are unskilled in airway management. Other devices that are suitable for noninvasive rescue strategies include the gum elastic bougie or an airway exchanger catheter (Cook Critical Care; Bloomington, IN). These devices may be useful in a situation in which the glottis can be only partially visualized and the insertion of the ETT into the trachea is unsuccessful. In a randomized study of 60 patients undergoing elective intubation with the application of cricoid pressure, the use of a gum elastic bougie was more effective than a regular stylet to facilitate intubation. Another tool included in the ASA DAA emergency pathway is retrograde endotracheal intubation, which entails passing a wire through the cricothyroid ligament in a cephalad direction until the tip can be retrieved through the nose or the mouth. A hollow guiding catheter is inserted in a cephalad direction over the guidewire, the guidewire is removed, and the ETT is then advanced antegrade over the guiding catheter into the trachea. A commercial kit for the procedure is available (Cook Critical Care). Success rates for the procedure vary. In a review of 1,368 patients undergoing endotracheal intubation in the emergency department, the authors found that retrograde endotracheal intubations were attempted in 8 patients, of which only four were successful. Among the complications encountered was the inability to pass the ETT through the vocal cords. To overcome this problem, Lenfant and coworkers have recently developed a modification of the technique in a human cadaver study. Insertion of the hollow guiding catheter antegrade through the ETT into the trachea prior to removal of the guidewire significantly increased the success rate from 69%, using the classic technique, to 89%, using the modified technique. It should be noted, however, that each provider participating in the study had previously performed at least 10 successful procedures in a cadaver, suggesting that this strategy should be carried out by experienced providers only. Should all alternative and noninvasive strategies to provide ventilation fail, a surgical airway has to be established. The two principal choices are cricothyroid-otomy and tracheostomy, either in a percutaneous or open surgical fashion. In a study comparing surgical cricothyroidotomy (Portex cuffed device; Smiths Medical Ltd; Hythe, UK) and wire-guided cricothy-roidotomy (cuffed and uncuffed version of Melker-set; Cook Critical Care) in an airway mannequin and artificial lung model, the cuffed devices provided more effective ventilation and tidal volumes. Furthermore, the surgical method was found to be quicker than the wire-guided approach (mean time to first breath, 44.3 vs 87.2 s, respectively) but may have a higher failure rate in inexperienced hands. Few data are available on the utility of percutaneous dilatational tracheostomy (PDT) for emergency airway access. In a case series of nine patients who were in severe respiratory distress, in which intubation by conventional means had been unsuccessful, all nine patients were successfully intubated using the PDT technique. The average time to gain access to the airway in the authors’ institution with this technique is reportedly 2.8 min, if performed by an experienced provider. Whenever possible, ventilation should be provided while access to the airway is being established (eg, LMA). While elective PDT in the critical care setting is safe and effective, more data are needed to establish its utility in emergency airway management.

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Fig2
Figure 2. Algorithm for airway management in the ICU. SB = spontaneous breathing; NMBA = neuromuscular blocking agent; DMV = difficult mask ventilation; pt = patient.