As we continue to advance our techniques, monitors and medications in order to optimize patient safety, we still struggle with postoperative respiratory compromise.
Respiratory events are a leading cause of anesthesia-related complications, especially in elderly and morbidly obese patients, and residual neuromuscular blockade is commonly involved.
The problem is so pervasive, however, that there seems to be limited concern or desire by many providers for advancement in assuring more complete recovery. A common statement is that what we have now is fine and that there is rarely, if ever (in my hands), significant morbidity from residual blockade. This has led to infrequent utilization of monitoring for adequate return of neuromuscular function, and the devices used require visual assessment of train-of-four and fade, which has been shown to correlate poorly with the true level of return of function. Quantitative analysis of train-of-four is not universally or even commonly utilized prior to extubation.
Furthermore, due to the unpredictability and slow onset of acetylcholinesterase inhibitors, as well as the infrequent use of adequate monitoring, those clinical situations, medications and pathology that could potentiate neuromuscular blockade seem merely academic. The antibiotics, calcium channel blockers, electrolyte abnormalities, long stays in the ICU and patient comorbidities are of minimal clinical relevance. We commonly wait multiple drug half-lives, note a train-of-four without fade utilizing qualitative devices, and see a reasonable clinical recovery with an adequate tidal volume and strength via head lift and hand grasp.
Therefore, it has been easy to assume that when patients do not “fly” from a respiratory standpoint prior to or after extubation, it is secondary to some other clinical mechanism unrelated to the utilization of neuromuscular blocking agents. Even though multiple studies have demonstrated that patients quite frequently are not appropriately reversed, and therefore have inadequate neuromuscular function even while extubated and lying in the recovery room, we find it difficult to believe that residual neuromuscular blockade is involved.
The introduction of sugammadex (Bridion, Merck), however, may be proving that our assumption about the lack of relevance of all these theoretical situations that could potentiate neuromuscular blockade may be incorrect, and what we have assumed to be “awake and strong” in the PACU may not actually be so. With sugammadex’s rapid removal of rocuronium and vecuronium from the nicotinic receptor site, leading to a quick and complete reversal of neuromuscular blockade regardless of the depth of paralysis at the time of administration, users are seeing remarkable improvement in strength and pulmonary function even in the most compromised patients, and I am confident that studies will eventually agree with the numerous case reports that lean toward a decrease in morbidity and mortality.
In my own practice, caring for many debilitated patients secondary to severe lung disease, multiple other organ system failures, and extreme morbid obesity, I have seen a dramatic decrease in respiratory compromise and failure in the immediate postoperative period. This has occurred since I started routinely utilizing sugammadex in patients receiving steroidal neuromuscular blockers, even when all indicators point to a lack of need for the reversal agent. It is easy to then assume that what we felt for years to be subclinical receptor blockade is not truly subclinical.
However, the adoption of sugammadex is not yet universal, partly because, as mentioned above, we have to recognize a problem before we can fix it. Some are concerned about cost, appropriately. And many providers see sugammadex as a “crutch” to cover for inappropriate utilization of neuromuscular blocking agents.
As the American Society of Anesthesiologists deems complications from residual neuromuscular blockade a “never event,” and since we now have in our hands a molecule that will reverse all levels of residual neuromuscular blockade quickly and completely, it is time to accept that our practice has been suboptimal and that our clinical assessment of partial paraly sis with whatever means we have chosen to use (or not) has been inadequate. We need to realize that we can do better.
Dr. Answine is clinical associate professor in the Department of Anesthesiology and Perioperative Medicine at Penn State College of Medicine, in Hershey, Pa. He is also a partner at Riverside Anesthesia Associates, and a staff anesthesiologist at UPMC Pinnacle, in Harrisburg, Pa.