The Advantages of the Lateral Decubitus Position After Spinal Anesthesia with Hyperbaric Tetracaine

Abstract

We investigated the effects of lateral decubitus positioning after spinal anesthesia with hyperbaric tetracaine on the spread of sensory blockade and hemodynamic variables. One hundred ASA physical status I or II patients scheduled for elective surgery to the lower limb received spinal anesthesia at a rate of approximately 0.1 mL/s using 0.5% tetracaine in 7.5% glucose with 0.125% phenylephrine in the lateral decubitus position with the operated side dependent. They were randomly divided into three groups: patients in Group I were placed supine immediately after spinal injection; those in Group II remained in the lateral position for 10 min before being turned supine; those in Group III were kept in the lateral position for 20 min then turned supine. Neural block was assessed by cold, pinprick, and touch sensation, and a modified Bromage scale. Hemodynamic variables included blood pressure, heart rate, and the use of ephedrine for the treatment of hypotension. The median (10th, 90th percentiles) peak dermatomal level to pinprick on the dependent side in Group III was T8 (T11, T5), which was significantly lower than that in Groups I and II, which extended to T4 (T9, T3) and T5 (T10, T2), respectively (P < 0.05). The difference in the maximal cephalad spread of sensory blockade between both sides in Group III was only one dermatome but was statistically significant (P < 0.05); in contrast, there was no significant difference in the maximal sensory level between both sides in Groups I and II. The use of ephedrine for the treatment of hypotension was significantly less frequent in Group III than the other groups. We conclude that keeping a patient in the lateral decubitus position for 20 min after hyperbaric tetracaine spinal anesthesia maintains preferential anesthetic distribution to the dependent side. Despite small differences between the two sides, the restricted spread of blockade and less hemodynamic variability may be clinically advantageous. The effects of posture on the spread of hyperbaric spinal anesthesia have not been adequately investigated. The results of the present study suggest an advantage of prolonged lateral decubitus positioning after intrathecal hyperbaric tetracaine.