Evidence-based practice is a laudable goal, but before acting on it we must have all the evidence. Two hours after an intubating dose of an intermediate acting muscle relaxant, Debaene et al.1
showed residual paralysis not recognized by subjective tactile or visual train-of-four monitoring. On the basis of this evidence, quantitative evaluation is recommended by the authors and is endorsed by the accompanying editorial. 2
Using awake volunteers, Eikermann 3
confirmed the presence of respiratory dysfunction detected by accelerometry that is not detected by more subjective analysis. However, what is not answered is, What is the morbidity and mortality caused by this “subjective” analysis? What is the morbidity and mortality of fixing the perceived problem? I have not seen a clinical problem with a patient intubated after rocuronium, a subjective train-of-four ratio of one at 1 hour later, and extubation without reversal. In fact, Eikermann reported, “Despite impaired upper airway function, no jaw thrust was needed, none of the volunteers reported dyspnea, and oxygen saturation remained greater than 96% at all times.” Clinically, quantitative analysis may yield false-positive test results that change our procedures so as to increase morbidity and mortality. Reversal of clinically insignificant paralysis may increase nausea and vomiting as well as increase airway secretions that may decrease pulmonary function. In an attempt to avoid problems with muscle relaxants, intubating without relaxants may cause laryngeal morbidity. 4
Resources and attention may be diverted from more significant factors. Outcome studies comparing the standard train-of-four with a more precise measurement of paralysis would provide evidence as to which is the best technique. Until we have such evidence it is premature to recommend a change in practice.
M. Craig Pinsker, M.D., Ph.D.