We read with interest the valuable comments of Schmartz et al ., which require some clarifications.
Succinylcholine was used in 14 patients (three in deep blockade [DB] and 11 in moderate blockade [MB]). After excluding patients administered succinylcholine, main data, expressed as median (range) and [percentile 10–90] were total dose of rocuronium (mg), 107.5 (70–290) [85.5–148.7] DB versus 100 (50–180) [68–157] MB, P = 0.169; total dose of sugammadex (mg), 250 (120–520) [200–454] DB versus 150 (100–320) [110–273] MB, P < 0.001; dose of sugammadex per real body weight (mg/kg), 2.30 (1.12–4.42) [1.51–3.925] DB versus 1.2272 (0.88–3.37) [1.0224–2.3638] MB, P < 0.001; time to train-of-four ratio of 0.9 s, 168.5 (20–460) [80–338] DB versus 111.5 (28–300) [49.7–213] MB, P < 0.001. In DB, 16 (40%) patients required a second dose of sugammadex and 14 (21%) in MB, P = 0.047. These results are not different from data presented.1Even if some activity of succinylcholine would be present, it was not determining the results of the study.
Sugammadex is able to quickly reverse a neuromuscular blockade (by <2 min); increasing the dose does not hasten recovery.2In our protocol, if the train-of-four ratio was less than 0.9, a second dose of sugammadex was administered after 3 min for DB and 2 min for MB. More than 20% and approximately 40% of patients with MB and DB, respectively, required a second dose. Delayed response to sugammadex is pointed out in most of the publications related to sugammadex administration to lean patients. In addition, the combination of underdose and delayed response has been associated with recurarization.3In favor of safety, tracheal extubation has to be performed when the train-of-four ratio 0.9 target is achieved. A delayed response to sugammadex (target not achieved at the expected time) makes tracheal extubation more challenging, especially in the morbid obese, who are at risk of potential airway serious complications; therefore, requiring close surveillance and neuromuscular monitoring.
In the first draft to ANESTHESIOLOGY, “Profound Blockade” was defined as “posttetanic count ≥ 1 to T1 appearance,” literal translation of the text in the observational study protocol (approval reference SAB-SUG-2011-01). Reviewers asked for a better description of DB, so we remade figure 1, modifying the definition of DB by using the number of twitches in the posttetanic count (posttetanic count = 0–12 twitches); however, on the draft we send and in the final draft version, “posttetanic count = 0–2 twitches” were written (this error was also reproduced in the text). This has created difficulty in interpreting methods. We apologize for that. Reviewing our database, all patients with DB had almost one twitch at posttetanic response count; therefore, no patient had intense neuromuscular blockade.
Even not significant, slightly more rocuronium was administered to patients with DB (even more after excluding patients administered succinylcholine). As it has been indicated, the interindividual variability to neuromuscular blocking agents is large, even more for rocuronium.4This variability could be facilitated by the association with sevoflurane in our patients.
When large doses of rocuronium have been used, we do not know how much rocuronium is still available after sugammadex administration. Redistribution of rocuronium might explain delayed response, or even outliers; however, this statement remains to be demonstrated.
Antoni Sabate, M.D., Ph.D.,*Sandra Llaurado, M.D.
Reanimation and Pain Clinic, Hospital Universitari de Bellvitge, Universitat de Barcelona Health Campus, Barcelona, Spain. email@example.com