LAUSR

Introduction Delivering definitive airway management using rapid sequence induction in a pre-hospital setting can indeed be a daunting task with little margin for error. Minor infractions at any step in the sequence can rapidly culminate to create an airway catastrophe. Nowhere else would the aggregation of marginal gains [1] reap more benefit than in such adverse conditions. In a recent issue of Anaesthesia, Angerman and colleagues [2] evaluated the effect of introducing a videolaryngoscope and a bougie into a standardised protocol for airway management. They demonstrated > 12% increase in firstattempt tracheal intubation success in a ‘before and after’ comparison. As it is widely accepted that airway complications increase with the increased number of attempts, this would represent a potentially significant improvement in patient care [3]. As tempting as it may be to attribute this success to the introduction of novel equipment, on closer scrutiny of the intervention, it is clear that the investigators are really comparing a new airway management protocol that included several ‘soft elements’ in teamwork communication, with an older, less standardised protocol (although this is somewhat understated in the title). It is difficult to tease out the marginal contribution that the pieces of equipment made without access to more information such as the specific reasons for the failed first tracheal intubation attempts in the cohort before the new protocol was introduced, such as an unfavourable Cormack–Lehane grade or difficulty encountered when manoeuvring the tracheal tube into the correct position. The before and after study design does not lend itself to such comparisons, and perhaps a prospective randomised trial is the only way to resolve this issue. The more important question is whether a prospective randomised controlled trial is worthwhile? If the pudding tastes great, does it matter which ingredient contributed to its success? There are situations when conducting randomised trials is neither feasible nor ethical, and comparing airway management in the pre-hospital setting might fall into this category. Using data from epidemiological studies, administrative databases and previously conducted clinical trials to estimate the effect of a placebo or standard of care, is one approach to assessing the benefits of a new therapy or protocol. However, the use of such ‘historical controls’ is not without its criticisms. Studies comparing a new treatment or method with historical controls may be unreliable as a mixture of retrospective and prospectively collected data will be used, and also due to unknown sources of bias. These sources of bias include: