Peripheral Skin Temperature Changes Following Spinal Anaesthesia for Category 4 LSCS

Regional anaesthesia of the lower limbs blocks sympathetic nerve fibres as well as sensory and motor fibres. It has been documented previously in the non-pregnant population that the blockade of sympathetic nerve fibres by regional anaesthesia (including spinal, epidural and lumbar plexus anaesthesia) results in vasodilation of peripheral blood vessels and an increase in the blood flow to the skin, increasing the peripheral skin temperature. Additionally thermoregulation has been found to be impaired more by spinal anaesthesia than epidural anaesthesia. The aim of the study is to measure peripheral skin temperature changes occurring in the lower limbs following spinal anaesthesia in the pregnant obstetric population undergoing category 4 lower segment caesarean section. The hypothesis is that peripheral skin temperature will rise following spinal anaesthesia and that this temperature change could be used as a measure of bilateral sympathetic block which may be an indicator of potential success of spinal anaesthesia. Future follow up studies could then potentially determine if peripheral skin temperature can also be used as a marker to determine the success of epidural analgesia for labour. The study will involve temperature measurement by Covidien Mon-a-Therm skin temperature probes and Braun Welch Allyn tympanic membrane thermometer devices on the dorsum of the right and left feet. The study will last from the time the parturient arrives in theatre for their lower segment caesarean section until the parturient leaves the recovery area.