Does Higher OT Temperature and IV Ondansetron Reduce Incidence of PSS in Parturients?

Overview

This study will look at the incidence of post-spinal shivering (PSS) among the obstetrics population and will investigate whether higher operation theater (OT) temperature range or/and IV Ondansetron are able to reduce the incidence of PSS. This is a double-blind, randomized, factorial study, patients will be grouped into 4 groups - LP, HP, LO, HO (L= low-temperature range, H= high-temperature range, P= placebo, O=Ondansetron). All patients undergoing cesarean section under spinal anesthesia will be recruited, and it will be conducted in obstetrics OT.

Many studies have been conducted to look at methods to prevent and treat postspinal shivering. However, there is still no clear protocol or gold standard for post-spinal shivering management. This is due to the fact that post-spinal shivering mechanisms are complex and are broadly grouped into thermoregulatory and non-thermoregulatory. Preventive measures that have been studied are broadly classified into pharmacological methods and non-pharmacological methods. For Non-pharmacological method, active warming of the patient by various methods have been found to be effective in preventing PSS. However, there is no study that looks at ways to reduce heat loss hence maintaining normothermia and preventing PSS in patients. Therefore in this study, we will be investigating if higher OT temperature will reduce the incidence of PSS. As for pharmacological methods, many drugs have been studied for examples analgesics (tramadol), opioid receptor agonists (pethidine, fentanyl), cholinesterase inhibitors (physostigmine), N-methyl-D-aspartate receptor antagonists (ketamine, magnesium sulphate), α2-central agonists (clonidine, dexmedetomidine), antiserotonergic (ondansetron) and anti-inflammatory drugs (dexamethasone). Ondansetron is usually used to prevent chemotherapy or radiotherapy-induced nausea vomiting and Post-operative nausea and vomiting. Due to the fact that it is generally a safe drug and has added benefit as an anti-emetics especially for obstetrics population, this drug is chosen to be studied. We will also look at the efficacy of the combined effect of increased OT temperature and prophylaxis ondansetron on preventing PSS.