Awake Total Neuromuscular Blockade as Experienced by Anesthesiologist Volunteers

Accidental awareness during general anesthesia can be profoundly traumatizing, even in the absence of pain.1,2 Neuromuscular blocking drugs are implicated in almost all cases of accidental awareness, yet despite having been in clinical use for more than 70 years, the subjective experience of awake neuromuscular blockade has been underinvestigated.We administered suxamethonium and rocuronium, on separate occasions, to 11 fully awake anesthesiologist volunteers in a previously published study of the Bispectral Index.3 We maintained communication during paralysis using the isolated-forearm technique and recorded the volunteers’ personal accounts the next day (tables 1 and 2). The study methods are included as Supplemental Digital Content (https://links.lww.com/ALN/D353).3The sensation of paralysis between the two agents was markedly different, quite apart from the painful fasciculations from suxamethonium. Suxamethonium paralysis felt like a profound heaviness throughout the body as if “a giant hand was pressing me deep into the table,” whereas, for most subjects, rocuronium paralysis felt indistinguishable from lying comfortably at rest. Some did not even realize that they were fully paralyzed until they deliberately tried to move.4However, if the ventilation was in any way inadequate, then dyspnea dominated the experience and, in some cases, caused marked distress. Subjects were ventilated manually via face mask, with initial tidal volumes of 7 to 10 ml/kg, at 10 to 12/min, targeting the lower end of normocapnia. Despite this, all subjects felt markedly short of breath and all signaled for much greater ventilation. The dyspnea did not resolve until tidal volumes were 12 to 15 ml/kg at 12 to 15/min. Previous studies have also described ongoing dyspnea at normal tidal volumes, in both volunteers and in chronically ventilated patients.4–6If subjects tried to breathe during paralysis, it immediately invoked a sense of suffocation and panic—unless that attempt coincided with a manually applied inspiration, in which case it felt perfectly normal, as if they were breathing by themselves. Attempts to swallow induced a sense of suffocation in four subjects, and even brief interruption of ventilation was poorly tolerated. One said, “I could hear the heart rate getting faster, and that the sats were still 100%. I knew you could handle airways much more difficult than mine, and that I wasn’t in any real danger, but at that point, I honestly felt that I was going to die.”The potential loss of the airway was an ongoing concern for many subjects. “My tongue seemed to take up all of my throat … it felt like a very very small crack between tongue and pharynx. It was unnerving thinking it might close at any point.” Conversely, the rapid recovery due to sugammadex was “like bursting out of the water after swimming the entire length of the pool—the most satisfying breath ever.”Attempts to move a limb or even just a toe during partial blockade, such as during the onset phase of rocuronium felt like trying to lift a very heavy object, consistent with previous reports.7 During dense paralysis, however, four subjects reported that any attempt to move a limb led to an immediate “horrible” sensation, which did not appear to be localized to the limb and which had a strong affective component. It was striking both in its unpleasantness, and its rapidity of onset, and it vanished almost as quickly once the attempted movement was ceased. Subjects were surprised to find they disliked the sensation so much they were not keen to try it again. One said that although a straight leg raise triggered the sensation, small “jiggling movements” of the legs did not. A fifth subject described “a kind of buzzing sensation either in the foot or in my mind—I couldn’t distinguish which,” while another found it “inexplicably hilarious.”The importance of the isolated forearm cannot be overstated. “Communicating with my hand was very comforting. I felt very warm toward the person holding my hand. When they let go, you don’t know if they are there anymore. It’s very lonely without that person holding your hand.” Another said, “The isolated forearm seemed to embody my only existence on earth. I felt as if I was hanging on to the outside world with that hand.”We have highlighted the distressing aspects of awake paralysis in this report, but for most of the time, the experience was not unpleasant. Indeed, all our volunteers found the experience professionally illuminating and said they would consider taking part in a similar trial again. Nobody declined to take part in the rocuronium trial because of their experience with suxamethonium. We suggest this is due to several factors. First, our subjects were self-selected, well-informed, and curious about the experience of awake paralysis. Second, they could communicate throughout, allowing optimization of their ventilation, and termination of the trial at any point. Third, they were clear-headed, without any confusion from the lingering effects of anesthetic drugs.8None of these mitigating factors apply to the patient who awakens accidentally while paralyzed. Furthermore, the feeling of suffocation induced by their own attempts to move and breathe while paralyzed will only intensify their anxiety. Because anxiety itself is a strong stimulus for ventilation, this may lead to a vicious cycle of ever-increasing distress, creating precisely the heightened emotional state that is required to develop long-term emotional harm.9,10 If a fully informed anesthesiologist can be transformed in seconds into a panicked state where they think they are “going to die,” consider the patient who is totally unprepared for the experience, has no comprehension of what has occurred, and no way to control it. They then realize to their horror that the operation is not over, but ongoing. Little wonder that many have ongoing symptoms of post-traumatic stress disorder for years afterwards.Our experience suggests that, in informed volunteers, deliberate awake paralysis is well-tolerated, provided that communication is maintained via an isolated forearm, and ventilation is greatly increased.5 The unpleasant aspects that we emphasized, some of which have not been described before, are crucial for understanding the experience of accidental awareness in unsuspecting patients and for those who might conduct future awake-paralysis studies in this relatively underexplored area.Support was provided solely from institutional and/or departmental sources.The authors declare no competing interests.Study methods, https://links.lww.com/ALN/D353