E. Laakso et al., KNEE-CHEST VS HORIZONTAL SIDE POSITION DURING INDUCTION OF SPINAL-ANESTHESIA IN PATIENTS UNDERGOING LUMBAR DISC SURGERY, British Journal of Anaesthesia, 79(5), 1997, pp. 609-611
In the prone knee-chest position the spread of plain 0.5% bupivacaine
in the cerebrospinal fluid and associated haemodynamic changes may be
different compared with the horizontal position. A randomized comparis
on was performed in 40 ASA I-II patients, aged 24-61 yr, undergoing lu
mbar disc surgery. Subarachnoid injection (27-gauge needle) at the L2-
3 interspace with 3 ml of 0.5% bupivacaine was performed with the pati
ent in the operative knee-chest position (prone knee-chest group, n=20
) or in the horizontal side position (supine side horizontal group, n=
20). Patients in the supine side horizontal group were turned into the
horizontal supine position for 20 min, and subsequently they were pla
ced in the operative knee-chest position. In three patients in the pro
ne knee-chest group, the spinal needle was replaced by a larger needle
(25-gauge). The final cephalad extension of sensory analgesia on skin
tested by pinprick was T5 (median) in the prone knee-chest group and
T6 in the supine side horizontal group. Recovery was also similar, on
average 210 min from injection in both groups. The mean decrease in sy
stolic arterial pressure was somewhat greater in the prone knee-chest
group (30 mm Hg) than in the supine side horizontal group (13 mm Hg).
The need for ephedrine occurred earlier in the supine side horizontal
group (three patients, all within 10 min from local anaesthetic inject
ion) than in the prone knee-chest group (six patients, all after 15 mi
n). Four of the latter patients also required administration of an ant
icholinergic for bradycardia compared with two patients in the supine
side horizontal group. Light sedation was given to five patients in th
e prone knee-chest group and to four in the supine side horizontal gro
up because of numbness and aching in the shoulders. We conclude that s
pinal block was similar in the two groups but there was a tendency to
more frequent episodes of haemodynamic deterioration in the knee-chest
position.