“In all debates, let truth be thy aim, not victory, or an unjust interest.”
― William Penn
In recent years, with the advent of sugammadex, rocuronium has become the muscle relaxant of choice for many anaesthetists performing a rapid sequence induction (RSI). The authors here conducted a systematic review to investigate if rocuronium is indeed comparable to suxamethonium in creating intubating conditions during RSI.
The authors searched the Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE for all RCTs and CCTs that directly compared rocuronium with suxamethonium during RSI and modified RSI. Other criteria included were a score for ease of intubation (Goldberg scale), a minimum dose of 0.6mg/kg for rocuronium and a dose of 1mg/kg for suxamthonium. The primary outcome was the proportion of excellent intubation conditions created during standard or modified RSI comparing rocuronium with suxamethonium.
Secondary outcome extended this to clinically acceptable conditions.
From the search, 50 studies involving 4151 patients were analysed. Suxamethonium was found to be superior to rocuronium for both primary and secondary outcomes; (RR (95%CI) 0.86 (0.81–0.92), 50 studies, 4151 participants) and (RR (95%CI) 0.97 (0.95–0.99), 48 studies, 3992 patients) respectively. Further subgroup analyses demonstrated that for standard vs modified RSI, suxamethonium was more favourable for both (RR (95%CI) 0.80 (0.72–0.89), 23 studies, 2535 patients) and (RR (95%CI) 0.92 (0.85– 0.99), 25 studies, 1468 patients) respectively. On the influence of rocuronium dose; at 0.6-0.7mg/kg was inferior to suxamethonium (RR (95%CI) 0.80 (0.72–0.88), 39 studies, 2808 patients). However at 0.9-1.2mg/kg there was no statistical difference for excellent and acceptable intubating conditions. When comparing thiopentone with propofol, thiopentone subgroup displayed preference for suxamethonium for excellent
conditions (RR (95%CI) 0.81 (0.73–0.88), 28 studies, 2302 patients). In the emergency setting, suxamethonium was once again superior (RR (95%CI) 0.84 (0.73–0.98), 5 studies, 1073 patients).
The authors concluded that there was moderate evidence to suggest that suxamethonium was superior to rocuronium in creating excellent and acceptable intubating conditions during RSI, more so, interestingly, in conjunction with thiopentone. The evidence was graded as moderate due to high risk of bias for blinding of outcome assessment. The fasciculations associated with suxamethonium effectively unblinds the assessor; in most cases the intubator was blinded but in 50% of cases the assessor was not. There was also a significant amount of heterogeneity (I2 statistic was never less than 50%). Subgroup analyses did not identify the reason for this; the authors suggested this was attributable to clinical variables and would, if anything, contribute to the generalisability of the results.
It was felt the authors posed a very clear and concise objective. However there was some discussion as to whether there was any merit to comparing suxamethonium with a dose of 0.6mg/kg rocuronium, as it is not considered an adequate dose for RSI. Achieving excellent intubating conditions at this dose at 1 minute would be futile.
We felt the literature search was comprehensive and recognise a manual search was conducted also. Study characteristics, inclusion and exclusion criteria were well documented, as well as reasons for exclusion. Standardised data collection forms were used.
On evaluation of the results; as mentioned above, there was a significant amount of heterogeneity. We agreed that this could indeed contribute to generalising the results. Such as, ease of laryngoscopy; laryngoscopy can be very user dependent; and perhaps choosing a muscle relaxant based on individual patient profiles.
Most agreed that as anaesthetists, we stick with what is familiar to us and works best in our hands. What was slightly less clear was when comparing suxamethonium with higher doses of rocuronium (0.9-1.2mg/kg), where there was no statistical difference for excellent or acceptable intubating conditions. Most anaesthetists we felt, as I alluded to earlier, would not use a smaller dose of rocuronium for RSI. Therefore, do we conclude this contest to be a tie, when using appropriate doses of agents?
These thoughts aside, we felt this was a well conducted systematic review which has clinical relevance to our daily practice.