RESUMEN
To assess the influence of gravity on epidural-induced sensory blockade during the first stage of labour, 60 parturients were recruited to a randomized, controlled, single-blinded study. In all cases an epidural catheter was placed with the patient in the left lateral position. Thereafter, patients were randomized to one of three groups. In group supine (S), the epidural injection was performed in the supine position with a 15-20 degrees right flank elevation and the patient remained supine. In group left (L) patients remained in the left lateral position for 10 min after injection. In group left and right (L+R) patients remained in the left lateral position for 5 min and then assumed the right lateral position for 5 min. Thereafter, in groups L and L+R patients lay supine with a 15-20 degrees right flank elevation. All patients received 50 microg fentanyl in 10 ml of 0.125% bupivacaine. Ten minutes after injection loss of pinprick and temperature sensation were assessed and pain scores measured. Height of sensory deficit 10 min after injection and after maximal blockade were unaffected by patient position. In all cases maximal blockade reached T8 or higher. Time to maximal block was 14.7 +/- 2.3 min, 14.1 +/- 1.6 min and 13.9 +/- 1.5 min for groups L, L+R and S respectively. After maximal blockade, pain scores were significantly (P<0.0001) decreased in all groups, with no differences between them. We conclude that position immediately following local anaesthetic drug administration has little effect on onset and distribution of epidural analgesia.