Another Arrow in the Quiver, for the Post-spinal Parturient Shiver!

Dear Editor, In the latest issue of Journal of Obstetric Anaesthesia and Critical Care, Meena et al.[1] outline an encouraging efficacy of prophylactic low-dose ketamine for the prevention of post-spinal anesthesia shivering in an elective setting for cesarean section (CS). Having investigated 80 American Society of Anesthesiologists (ASA) physical status II parturients in a meticulous randomized double-blind manner alongside equally objective exclusion criteria, the authors are commended for adding to the existing knowledge in a clinically pertinent obstetric topic.[1] We, however, believe that some other intricate aspects of the index research frame, necessitate deliberation. To begin with, the sample size in the present study was premised on the Rabi’u et al. randomized controlled evaluation of prophylactic ketamine for post-spinal shivering in a mixed cohort of ASA I and II women undergoing vesicovaginal fistula repair.[2] While Meena et al. research exclusively involved pregnant women where pregnancy by itself classifies as an ASA II physical status; it is noteworthy how the Rabi’u et al. study which included as many as 92.68% ASA I patients with a rather limited representation of the ASA II physical status, was hereby employed for the sample size enumeration.[1,2] Second, the recent literature on the corresponding subject has further interesting facts to elucidate. A prospective observational study by Jeevan et al. highlights preoperative patient anxiety as an independent risk factor for post-spinal shivering in CS with an adjusted odds ratio (aOR) of 1.21; 95% confidence interval (95% CI) of 1.06–1.37 and a P value of 0.005, for an elevated Amsterdam Preoperative Anxiety and Information scale or the APAIS.[3] In addition to the APAIS scores, anxiety on the visual analog scale was also found to be significantly associated with post-spinal shivering (aOR: 1.48; 95% CI: 1.24–1.78, P < 0.001).[3] The former could indeed have had an important role to play in the Meena et al. study, especially, given the indigenous educational, socio-economic, and cultural considerations.[1] Finally, amidst a total of 11 participants in the index study experiencing nausea-vomiting, it remains to be clarified whether or not Meena et al. administered ondansetron to these parturients.[1] The preventative effect of the latter on post-spinal shivering happens to be suggested by independent researchers (Zhang et al.[4]), which becomes all the more relevant when the complication under investigation has a wide reported incidence of 36%–71%.[3,5] Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.