LAUSR

Difficult or failed tracheal intubation following induction of general anaesthesia in the obstetric patient is more frequent than in the non-obstetric population, and difficulties with airway management remain a major contributing factor to anaesthesia related maternal morbidity andmortality [1,2]. The ability to accurately predict a difficult airway could facilitate planning and preparation and predict a difficult airway. In addition, in obstetric practice, airway assessment is often hindered by the limited time available to assess the airway in an emergency. The need for antenatal anaesthetic assessment for womenwith a potential difficult airway is obvious [3]. But the question arises as to how does one predict a difficult airway?When used in isolation, bedside tests have poor predictive values. Despite being one of the more popular bedside tests, the original and modified Mallampati grading have low sensitivity (42e81%), specificity (53e89%) and positive predictive values (2e21%) [4]. In addition, Mallampati score is not consistent, as itmay increasewith advancing pregnancy and labour [5]. In the current issue, Jarraya A et al. [6] evaluate novel indicators for predicting difficult airway in obstetric patients. They found that Mallampati score (sensitivity 99%, specificity 64%), chest circumference-to-sternomental distance ratio (sensitivity e 80.6%, specificity e 70.5%), weight gain during pregnancy (sensitivity 71%, specificity e 83.9%) and neck circumference (sensitivity e 71%, specificity e 89%) were independently associated with difficult intubation. Previously, Honarmand et al. [7] conducted a similar study comparing Mallampati score, upper lip bite test and height to thyromental distance ratio. Only the height to thyromental distance ratio was a potentially useful screening test for difficult laryngoscopy, with a sensitivity of 71.4% and specificity of 98.1%. When bedside tests are used in combination, the chances of predicting a difficult airway increase [8e11]. The low predictive value of ‘established’ assessment methods is the driving force for constantly searching for better ones. This makes studies like Jarraya A et al. useful in their own right [6]. Yentis in 2002 wrote an editorial titled ‘Predicting difficult intubation e worthwhile exercise or pointless ritual?’, in which he challenged the process of airway assessment. He ended his editorial with a conclusion that although predicting difficult intubation is unlikely to be useful, it should still be carried out as it forces the anaesthetist to think about the airway [4]. Sixteen years later, a Cochrane review by Roth et al. also concluded that bedside tests are not suited for the purpose of detecting an unanticipated difficult airway, as they fail to detect a large proportion of difficult airways [12]. Perhaps the way forward for airway assessment is to approach it differently. Firstly, we need to define what is meant by a difficult airway, and secondly, we need to embrace new technology that may assist us in improving the positive predictive values of airway assessment.