EFFECT OF POSITION ON DURATION OF SPINAL BLOCKADE IN OBSTETRICAL PATIENTS

Abstract

S377 INTRO: Several studies and texts [1,2,3,4,5] have suggested that hyperbaric spinals placed with patients in the left lateral decubitus position give inadequate blockade for cesarean section. This recommendation is in contrast to the standard clinical practice at several institutions. We, therefore, conducted the following study to determine if patient position during the placement of spinal blockade affected adequacy or duration of anesthesia. METHODS: After an investigational review board approval, and obtaining informed consent, 33 women presenting for elective cesarean section within 3 weeks of term were randomized to one of two groups, either left or right lateral decubitus position for placement of the spinal anesthetic. Fetal heart rate was monitored using the doppler technique throughout spinal placement. A 25 gauge Whiticare spinal needle was placed at the L3-4 or L4-5 interspace. 1.6 ml of 0.75% bupivacaine mixed with 8.25% dextrose and 0.3 mg of preservative free morphine was injected into the intrathecal space after needle placement was confirmed by free flow of CSF. Immediately after withdrawing the spinal needle, the patient was turned supine and left uterine displacement was achieved using a right hip wedge. Spinal sensory levels were assessed at 2, 5, 10 and 90 minutes bilaterally following spinal placement using loss of sensation to pin prick by a blinded observer. Maximal blood pressure drop, ephedrine dose, 1 and 5 minute Apgar scores, fetal cord pH, and surgical duration were recorded for each patient. The results were analyzed using two sample t-test. P=0.05 was considered significant. A power analysis was conducted for sample size determination. RESULTS: 18 patients were randomized to the left lateral decubitus position while 15 were randomized to the right lateral decubitus position. There was no statistically significant difference between groups in any measured variable (see Table 1). pH values were obtained for 8 patients in each group.Table 1In no patient was the anesthetic considered inadequate or was postural manipulation required to facilitate cephalad spread the local anesthetic. CONCLUSIONS: Despite previous reports in the literature to the contrary, we found that patient position during placement of hyperbaric spinal blockade had no statistically significant effect on the duration or effectiveness of spinal anesthesia. In addition, there were no adverse effects on the fetus as measured by fetal heart rate tracings during spinal placement, cord pH or Apgar scores.