Revi N, Binu P. Simon, Deepak S
BACKGROUND The caesarean section under spinal anaesthesia is a common procedure performed in operation theatres. Perioperative shivering and hypothermia will be present in the majority of these cases. Shivering is bothersome to mother and the anaesthesiologist and will impair early maternal bonding to the baby. The maintenance of normothermia is an important function of the autonomic nervous system. Autonomic blockade at spinal level leads to internal redistribution of heat from the core to peripheral compartment and a rapid decline in core temperature. It is often challenging to treat core-peripheral redistribution of heat. However, redistribution can be prevented by preanaesthetic cutaneous warming. The purpose of this study is to compare the efficiency of forced air pre-warming and pre-warmed intravenous fluids 15 minutes prior to spinal anaesthesia in patients undergoing a caesarean section. MATERIALS AND METHODS This is a prospective cohort study conducted in 72 term mothers of ASA class I and II in the age range between twenty and thirty years, scheduled for caesarean section under spinal anaesthesia in our institute during a period of 6 months. 24 patients who received forced external air warmers were designated as group E and 24 patients who received warmed intravenous fluids as a method of prewarming were designated as group F. The remaining 24 patients received neither of these and were designated as group C. Intraoperative blood pressure, heart rate, level of sensory blockade, presence of nausea, vomiting, fluids given, and blood loss were monitored. Core temperature was measured using an infrared thermometer (GT- 302A) every 15 minutes after spinal anaesthesia. Skin temperature was measured using a Skin Temperature Probe??? (NIHON KOHDEN) every 15 minutes after spinal anaesthesia. The intensity of shivering was graded using a scale from 0 to 3. RESULTS The mean skin and core temperature measurements immediately after spinal anaesthesia to the last measurement at 1 hour of forced air warming group E & warm intravenous fluid group F was found to be higher than control group C. It was statistically significant (p-value > 0.05). The mean skin temperatures and core temperatures observed immediately after spinal anaesthesia for group E, group C and group F were 34.838±.16100C/35.692±.16130C, 34.633±.26150C/35.446±.27020C and 34.788±.24370C/35.617±.27770C respectively. There was no statistically significant difference in mean and core temperatures between group E & F. Incidence of clinically appreciable shivering (grade 2& 3) in group E is 8/24(33.3%), Group C is 22/24(91.6%), and Group F is 12/24(50%). CONCLUSION Prewarming with forced air warmer and warm intravenous fluids markedly increases peripheral heat content causing the decreased core to periphery temperature gradient. Active warming measures are effective in preventing hypothermia when they are applied preoperatively.
