Withdrawal movements associated with the injection of rocuronium.

Abstract

We read with interest the article of Shevchenko et al. (1) demonstrating that the IV injection of rocuronium is commonly associated with a withdrawal reaction in anesthetized pediatric patients. They observed that the incidence of withdrawal was 85% and that it was significantly decreased to 46% in patients pretreated with IV lidocaine. In this article, both introduction and conclusion statements deal with the probability that the withdrawal movements are secondary to discomfort or to painful stimulation at the site of injection. We are surprised that such statements are still presented as hypothetical explanations. Indeed, Steegers and Robertson (2) showed that administration of a subparalyzing dose of rocuronium in awake patients is correlated with pain on injection: 47% of the patients had pain and 12% described it as severe. Our group (3) showed, in a double-blinded, placebo-controlled trial in awake patients, that the IV administration of 10 mg of rocuronium, under venous tourniquet conditions, produced pain described as intense and burning, by all patients. We found a good correlation between the verbal description (unpleasant feeling, moderate, and severe) and the VAS measurements (0–10) of this pain (VAS of 10, 5, and 2, respectively). Furthermore, the extent of withdrawal movement was also correlated with the pain intensity from slight flexion of the wrist to sudden flexion of wrist and elbow, respectively. We investigated, in another double-blinded, placebo-controlled trial (4), the effects of prior administration of fentanyl on these movements. All patients received fentanyl 2 μg/kg, then propofol mixed with lidocaine, and 60 s later rocuronium 0.8 mg/kg. We found a statistical decrease of the incidence of movements, which is in accordance with the results found by Shevchenko et al. (1). The authors found a 48% incidence of generalized movements (present in more than one extremity, cough, or breath-holding). Interestingly, we never noticed such generalized movements after rocuronium administration, in neither pediatric nor adult patients; the maximal extent of observed movements was limited to the girdle part of the extremity concerned with the injection. The results of Shevchenko et al. (1) show that pretreatment with lidocaine only significantly reduced the incidence of generalized movements (48% vs 12%) and did not decrease the incidence of movements limited to wrist or arm (36% vs 34%, respectively). In their study, induction of general anesthesia was performed with 2.5% sodium thiopental followed 5 s later by the administration of rocuronium. This practice may introduce an observational bias on the observation of withdrawal movements associated with rocuronium, because thiopental itself can cause pain on injection and withdrawal movements, especially in children who have smaller veins. In this article, the authors failed to mention or to discuss the different features of observed withdrawal movements between pediatric and adult patients. Finally, the study of Shevchenko et al. (1) failed to bring new pathophysiological understanding of the pain produced by the injection of rocuronium. Our group showed that the pain was not associated with the pH of the injected solution and was diminished by a second subsequent injection of rocuronium 30 s later. This pain shows many common features with the one associated with propofol administration. We hypothesized, as histamine was unlikely, the possible role of mediators of the kininogen cascade (3,4). This hypothesis was recently investigated by Joshi et al. (5), who demonstrated the preventing effect of nafamostat mesilate, a kallikrein inhibitor, on the pain produced by the injection of propofol. There are new ways and possibilities to investigate the pain associated with rocuronium or other drugs during IV administration; further studies in this clinical context will be welcome. Yvan A. Ruetsch MD Alain Borgeat MD