EFFECT OF FORCED AIR PREWARMING,TRAMADOL OR THEIR COMBINATION ON PREVENTION OF HYPOTHERMIA AND SHIVERING DURING CESAREAN SECTION UNDER SPINAL ANESTHESIA.

Abstract

Background and Objectives: Hypothermia and shivering are common side effects accompanying regional anesthesia Shivering occurs in up to 85% of patients undergoing cesarean delivery under spinal anesthesia and it has deleterious metabolic and cardiovascular effects. Therefore, hypothermia and shivering should ideally be prevented by pharmacologic or other means. We evaluated the efficacy of forced-air prewarming, tramadol or their combination in preventing perioperative maternal hypothermia and shivering in patients undergoing spinal anesthesia for cesarean section and effect on neonatal outcome. Methods: 105 patients undergoing elective cesarean section under spinal anesthesia were randomly assigned to three groups. Group T received Tramadol 1mg/Kg. I.V. with no prewarming. Group F received forced-air prewarming for 30 min. Group TF received Tramadol 0.5mg/Kg I.V. just before giving block plus forced-air prewarming for 20 min.. Core temperature (tympanic membrane) and the arm skin temperature were measured and shivering was graded simultaneously. Patients evaluated their Thermal comfort with visual analog scales. Rectal temperature, umbilical vein pH and Apgar score were measured in the infants after birth. Results : The core temperature was significantly lower in group T than in the two other pre-warmed groups (group F and group TF) at 30,45, 60, after intrathecal injection (P <0.05) with no difference between group F and TF.The mean skin temperature was statistically lower (P <0.05) in group T compared with groups F and TF until 60 minutes after intrathecal injection. Incidence of hypothermic patients was significantly less in F and TF groups being 5.7% in both groups compared to group T (60%), (P = 0.001) with lower necessity and shorter duration of active warming in groups F and TF. Shivering incidence was significantly higher in group T and group F being 23% and 25.7% respectively, compared to group TF being 0% (p<0.005). Patients received pethidine to control shivering were significantly low (0%) in Group TF compared to Groups T and F (p<0.05), with no difference between Groups T and F. Umbilical vein pH, rectal temperatures and apgar scores of the newborns were higher in babies of group F and TF (actively prewarmed mothers) than in the babies of group T ( non pre-warmed mothers) (p<0.05) . Conclusions: The combined use of 20 min upper body forced air prewarming plus tramadol 0.5mg/Kg was more effective in preventing maternal core hypothermia and shivering and improving maternal thermal comfort and satisfaction with better neonatal outcome in patients undergoing cesarean delivery under spinal anesthesia compared with either prewarming for 30 min or tramadol 1 mg/Kg alone. Keywords: Anaesthesia spinal, caesarean section, hypothermia, prewarming, shivering, tramadol,