The effect of head-down tilt on arterial blood pressure after spinal anesthesia.

We examined the usefulness of 10 degrees head-down tilt for hypotension after spinal block. Two different investigations were performed, one employing head-down tilt after arterial blood pressure had decreased (n = 40), and the other using a prophylactic tilt (n = 50). When the head-down tilt was applied to treat hypotension after spinal block (n = 40), arterial blood pressure increased only in patients whose systemic blood pressure decreased more than 30% from the control (severe hypotension group, n = 11). However, even in the severe hypotension group, systolic blood pressure did not increase in two patients after 10 degrees head-down tilt. When the head-down tilt was performed immediately after spinal block (n = 24), the changes in systolic blood pressure were the same as in the horizontal group (n = 26). The cephalad spread of analgesia at 20 min after spinal block was higher, however, in the head-down tilt group (T3.8 +/- 1.6) than the horizontal group (T5.2 +/- 1.9). From these results we conclude that head-down tilt for hypotension after spinal block increases arterial blood pressure only for severe hypotension, and that prophylactic head-down tilt has no effect in maintaining blood pressure.