Spinal anaesthesia for cesarean delivery; study of different doses of IV ephedrine as prophylaxis to prevent hypotension during

ABSTRACT

To determine the effective dose of intravenous ephedrine for the prevention of hypotension during spinal anesthesia for cesarean delivery. A randomized, double-blinded dose finding study. The study was carried out in Combined Military Hospital Gujranwala from March 2009 to March 2010. Total patients were 80 full term women who were randomly allocated into four groups and were given Ringer lactate 10 ml per kg body weight intravenously. One minute after the spinal injection, patients were given saline control or ephedrine 0.1 mg per kg body weight, 0.25mg per kg body weight, or 0.4mg per kg body weight for 30 seconds. The study period started at the time of spinal injection and continued for 15 minutes. Systolic arterial pressure and heart rate were recorded at 1 -min intervals. Side effects like hypotension, hypertension, tachycardia, bradycardia, nausea and vomiting were also recorded. Total rescue ephedrine and total dose of used ephedrine in all groups were measured. Neonates were assessed by APGAR score. There was less incidence of hypotension in the ephedrine 0.4mg per kg body weight and 0.25 mg per kg body weight group as compared with ephedrine 0.1 mg per kg body weight and the control group, 5[25%], 13[65%] vs. 16[80%], 18 [90%] respectively. Systolic arterial pressure [SAP] in the first 15 min after the spinal injection was statistically significant greater in the 0.4mg per kg body weight group compared with other groups [P <0.001]. Reactive hypertension occurred in 9[45%] in the 0.4mg per kg group, compared with control group, 0[0%], ephedrine 0.1 mg, 1[5%] and ephedrine 0.25 mg 3[15%] patients. The Heart rate in the first 15 minutes in the ephedrine 0.4mg per kg body weight and 0.25 mg per kg body weight group was statistically significant higher than those of ephedrine 0.1 mg per kg body weight and control group [P<0.001]. The incidence of tachycardia was more in ephedrine 0.4 mg per kg body weight and 0.25 mg per kg body weight groups as compared to ephedrine 0.1 mg per kg body weight and the control group, 9 [45%], 6 [30%] vs. 3 [15%], 2 [10%] respectively. There were significant decrease in total doses of rescue ephedrine required in the ephedrine 0.4mg per kg body weight group as compared to other three groups. Total doses of used ephedrine in all groups were similar. We conclude that although ephedrine 0.25 mg per kg body weight reduces the hypotension but the smallest effective dose of ephedrine to reduce the incidence of hypotension significantly was 0.4mg per kg body weight