VOLUME 30, ISSUE 1

** These recommendations represent the views of the authors and do not represent any official statement from the American Society of Anesthesiologists or any other medical societies.

Safe perioperative airway management relies on good patient evaluation, anticipation of intubation and ventilation difficulties, and planning for alternative airway strategies. The unanticipated difficult to intubate/difficult to ventilate airway has the potential to impose serious complications and adverse outcomes that can escalate rapidly to emergent surgical airway attempts, hypoxic brain injury or cardiopulmonary arrest (1). The American Society of Anesthesiologists (ASA) difficult airway algorithm was created in order to guide anesthesiologists in the management of the various complications associated with difficult airways and to provide a systematic method to lessen the likelihood of such adverse outcomes (1).

The original guidelines were introduced in 1993 by an ASA appointed task force that consisted of anesthesiologists in academic and private practices from several regions across the United states and two consulting methodologists from the ASA Committee on Standards and Practice (1). The guidelines were updated in 2003 to incorporate new literature and to include advances in airway techniques (1,2). These updated guidelines included the addition of the laryngeal airway mask (LMA) to be used as ventilatory support or for intubation in the awake induction pathway. Further modifications included listing “difficult ventilation” first, and the addition of “difficult tracheostomy” in assessing the likelihood of airway management problems. There was also the addition of pursuing “opportunities to deliver supplemental oxygen throughout the process of difficult airway management”. In considering the “relative merits and feasibility of basic management choices”, awake intubation is now considered before “noninvasive versus invasive techniques as the initial approach to intubation.” Lastly, the option for “one more intubation attempt” was removed, and the use of the rigid bronchoscope was added as an option for emergency non-invasive ventilation (1,2).

The ASA revised the algorithm once more in 2011, with the most current guidelines being adopted in 2013. The most recent guidelines have added “difficult supraglottic airway (SGA) placement”, “difficult laryngoscopy” and “difficult surgical airway access” under the “assessment of the likelihood and anticipated clinical impact of six basic problems that may occur alone or in combination”. The term SGA has replaced LMA, and additional definitions related to difficult SGA placement have also been added. Further, video-laryngoscopy should be considered as an initial approach to intubation and in situations in which intubation has failed and mask ventilation is adequate (2).

What remains controversial is the practice of administering neuromuscular blockade (NMB) as a means to improve facemask ventilation (FMV) and where this might fit into the ASA’s Difficult Airway algorithm. While numerous studies have demonstrated improved FMV with the administration of NMB (7-9), there remains concerns that these drugs might “burn a bridge” or take away the ability to wake the patient up. Traditionally for many, succinylcholine has been looked at as the NMB that provides the option to return a patient to spontaneous respiration and is entertained as a method to improve FMV and intubation conditions. However, succinylcholine is not an ideal drug in this situation as its many side effects and contraindications limit application and its effects can linger for as long as 11 minutes following administration (10). Rocuronium on the other hand, has much fewer side effects and results in similar times and ventilation/intubation conditions compared to succinylcholine (10). The unfortunate consequence of rapid sequence dosing (1.2 mg/kg) of rocuronium is that it results in deep neuromuscular blockade with a duration of action lasting 67 +/1 27 minutes (11). Even with administration of neostigmine, “waking up the patient” with rocuronium in this scenario is not an option. Until the advent of the reversal agent sugammadex, administration of neuromuscular blockers was in many ways crossing a point of no return.

The unique reversal agent sugammadex is a modified cyclodextrin with a lipophilic core and a hydrophilic periphery. Its molecular structure resembles a cup that sequesters steroidal muscle relaxants for excretion via the kidneys (3). Sugammadex was first approved by the European Union in 2008, and has since proven to be efficacious and is supported by a large body of scientific data and millions of safe patient exposures (4,5). After three attempts for approval in 2008, 2012, and 2014, the drug was approved by the Food and Drug Administration for use in the United States in December 2015 (3). Sugammadex holds several notable advantages when compared to anticholinesterase reversal agents. One of the most significant advantages is its ability to reverse profound neuromuscular blockade more rapidly and effectively than neostigmine. Sugammadex has been found to reverse blockade three to eight times faster than neostigmine, with deeper levels of blockade proving more advantageous for sugammadex when compared to neostigmine (5). The current recommendations for dosing are 2 mg/kg for a shallow block (two train-of-four responses), 4 mg/kg for a level of two post-tetanic responses (deep block), and 16 mg/kg for rescue reversal after a large dose of steroidal muscle relaxant has been given. It has been demonstrated that neuromuscular blockade (TOF count of 0) can be reversed with 4 mg/kg within 3 minutes versus neostigmine, which is less reliable in deeper levels of blockade (4). Additionally, the incidence of postoperative residual blockade with TOF ratio <0.9 is significantly lower with sugammadex compared to neostigmine (5). A study done by Blobner et. Al. showed similar results with a time to recovery of the TOF ratio of 0.9 after sugammadex compared with neostigmine was 1.5 versus 18.6 minutes (P < 0.0001) (4,6). The predictability of response was demonstrated to be greater with sugammadex than neostigmine, with 98% of sugammadex patients versus 11% of neostigmine patients recovering to a TOF ratio of 0.9 within 5 minutes (4,6). Furthermore, numerous cases reports have demonstrated the utility of sugammadex in reversing NMB during a failed or difficult airway (3,5).

Therefore, in light of its clinical utility in reversing deep neuromuscular blockade rapidly and effectively, suggamadex makes it possible to incorporate early rocurnium administration to improve FMV or intubation conditions in the difficult airway. We recommend rocuronium administration with the rapid availability of sugammadex administration be incorporated into the ASA difficult airway algorithm. Administration rescue does of IV 16 mg/kg sugammadex be added as follows:

(1) Initial Intubation attempts UNSUCCESSFUL: 1. Consider calling for help 2. Returning to spontaneous ventilation; Consider administering 16 mg/kg of IV sugammadex if steroidal muscle relaxant given 3. Awakening the patient

(2) SGA not adequate or feasible → Emergency Pathway: 1. Call for help 2. Administer 16mg/kg of IV sugammadex if steroidal muscle relaxant given.

The usefulness of rocuronium to facilitate intubation and ventilation with sugammadex rescue in assisting patients who are in the “cannot ventilate, cannot intubate” situation to return to spontaneous ventilation has been well documented in case reports (3). We believe that the addition of Sugammadex to our clinical practice and to the ASA Difficult Airway algorithm will provide additional options that were previously considered unsafe and, thereby, enhance patient safety.

Please see red lettering in modified diagram: