L. Niemi et al., EFFECT OF LATE POSTURE CHANGE ON THE LEVEL OF SPINAL-ANESTHESIA WITH PLAIN BUPIVACAINE, British Journal of Anaesthesia, 71(6), 1993, pp. 807-809
We studied 40 patients, 18-60 yr, undergoing orthopaedic surgery of th
e lower limb under spinal anaesthesia. A midline lumbar puncture was p
erformed in the L3-4 interspace using a 27-gauge needle with the patie
nt in the lateral horizontal position. Plain bupivacaine 3 ml at room
temperature was injected. The cephalad level of analgesia was assessed
by pinprick 60 min after injection of local anaesthetic, at the end o
f surgery and again after the patient was moved into bed. All patients
had a segmental level of the block of L1-T5 at the beginning of the s
tudy. The upper half of the patient's body was then tilted to a 30-deg
rees head-up position. Segmental spread was subsequently assessed by p
inprick at 5-min intervals for 30 min. In six of the 40 patients (15%)
, increased cephalad spread of spinal analgesia occurred. The mean tim
e from induction of spinal anaesthesia was shorter in these six patien
ts (mean 92 min, range 80-115 min) than in the patients whose block di
d not change or was decreasing during the 30-min test (mean 119 min, r
ange 83-210 min) (P < 0.05). We conclude that the patient should remai
n in the supine horizontal position until recovery from the spinal blo
ck.