A response to ‘Obesity and obstetric anaesthesia’

Abstract

In their otherwise comprehensive review on obesity and obstetric anaesthesia, Saravanakumar et al. [1] omit some important points. They refer to the prevalence of obesity in women of childbearing age. Perhaps more relevant is the prevalence of obesity in women requiring anaesthetic intervention on the labour ward. Two recent reports indicate that this ranges from 7.5% (women with BMI of 35 kg.m−2 or more) [2] to 15% (women with BMI of 30 kg.m−2 or more) [3]. A local audit of 1096 such women shows that almost 40% were either overweight or obese (unpublished data). With regard to the technical difficulties with regional techniques in obese parturients, we found, as expected, a significant increase in difficulties establishing epidural analgesia, but no increase in the requirement for re-siting or in the failure of the epidural to provide satisfactory surgical anaesthesia for emergency Caesarean section in labour compared with non-obese women. Although the depth to the epidural space is correlated with BMI (as stated in the review), it is a poor correlation and of limited predictive value. We found r = 0.4, Stockton et al. found r = 0.3 [4], and Watts also reported a poor correlation [5]. In discussing the relative merits of the sitting position for performing regional techniques in obese women, the authors omit to mention that there is a significant increase in the incidence of unwanted epidural venous cannulation in this position when compared with the head-down, lateral position, presumably due to reduced epidural venous distension [6]. Finally, there is no mention of the technique of local infiltration anaesthesia for Caesarean section in obese parturients which has been reported in the literature [7]. Exceptionally, this technique might be useful in the event of maternal collapse or if in extremis general and regional anaesthesia are considered contra-indicated. It is perhaps a skill that trainee obstetricians should revisit. We currently have on our staff an obstetrician from Sudan who has considerable experience of this technique.