Comparison of video laryngoscopes with direct laryngoscopy for tracheal intubation

Abstract

Editor, The recent meta-analysis of Su et al.1 comparing video laryngoscopes with direct laryngoscopy for tracheal intubation was of great interest to us. Although their findings are consistent with the current literature, we believe that many questions remain on this issue. First, it is surprising that no study evaluating the Airtraq has been included in the meta-analysis. The authors declared they had searched PubMed and EMBASE up to 24 September 2010. They considered only randomised clinical trials with at least two independent groups comparing video laryngoscopes with direct laryngoscopy. With these criteria, they included only 11 reports in the meta-analysis and in none of these were the Airtraq studied. However, with the same criteria, we identified at least two more articles that should have been included in the analysis. In the study of Maharaj et al.,2 the Airtraq was compared with the Macintosh laryngoscope in patients deemed at low risk for difficult intubation in a randomised controlled trial. In this study, the Airtraq provided comparable or superior intubating conditions in the normal airway and did reduce intubation difficulty as evaluated with the intubation difficulty scale (IDS).3 The same authors compared the Airtraq with the Macintosh laryngoscope in patients at increased risk for difficult tracheal intubation.4 The Airtraq reduced the duration of intubation attempts, the need for additional manoeuvres and the IDS score. It should also be mentioned that, recently, Lu et al.5 carried out a systematic review and meta-analysis on Airtraq, concluding that it facilitates a more rapid and accurate intubation, especially when used by novices. Su et al. stated that this is the first meta-analysis of randomised trials evaluating the video laryngoscope with direct laryngoscopy. This is not completely true, as Mihai et al.6 recently performed a quantitative review and meta-analysis including other devices such as Bonfils and failed to provide strong evidence that video laryngoscopes should supersede the Macintosh laryngoscope. To omit some studies may lead to misleading results in meta-analysis.7 In our opinion, focusing meta-analysis on single devices is more useful and should help us to evaluate the performance of each tool. We agree with the authors about the limitations of the study that are related to the nature of the subjects. There is little doubt that randomised trials and their meta-analyses constitute very persuasive evidence. However, randomised trials are not the only source of evidence and it has gradually become apparent that perfectly pragmatic decisions could also be based on ‘lower’ levels of evidence. It is time for a new approach in this area of research, or the questions will never find a definitive answer. Acknowledgements Assistance with the study: none declared. Sources of funding: There was no contribution from any other person and the authors did not receive any financial support. This work was supported by the Department of Emergency, Anaesthesia and Intensive Care Section ‘G.B. Morgagni-Pierantoni’ Hospital, Forli, Italy. Conflicts of interest: None of the authors declares any conflict of interest.