Several studies have indicated that the addition of sodium bicarbonate and opioid to solutions of local anesthetics shortens the onset time, increases the intensity and prolongs the duration of neural blockade. This study was performed to compare
onset
times and duration of neural blockade in each groups.
Eighty-two parturients scheduled for cesarean section at term under epidural anesthesia were assigned to three groups. Group 1 (n=19) received 1.5% lidocaine hydrochloride (pH 6.32(0.01), group 2 (n=26) received 1.5% lidocaine hydrochloride plus
fentanyl 50 mcg (pH 6.27(0.02) and group 3 (n=37) received 1.5% lidocaine hydrochloride plus fentanyl 50 mcg plus 8.4% sodium bicarbonate (sodium bicarbonate 1 mEq/lidocaine 10 ml)(pH 7.32(0.03). All groups were given 22-28 ml of local anesthetic
solutions according to their height.
Onset times and duration of sensory blockade were evaluated using pin prick test at two minutes interval after epidural injection at L2, T6, T4 dermatomes. Onset times (time between the completion of anesthetic injection and loss of pin prick
sensation
at each dermatome) of sensory blockade at L2 dermatome were 3.1(0.2 minutes n Group 3, which were shorter than 5.0(0.3 minutes in Group 1 and 4.7(0.4 minutes in Group 2 (p<0.05). At T6 dermatome, onset times of sensory blockade were 6.9(0.6
minutes
in
Group 3, which were shorter than 15.4(1.2 minutes in Group 1 and 12.9(1.0 in Group 2 (p<0.05). At T4 dermatome, onset times of sensory blockade were 10.1(0.2 minutes in Group 3, which wee shorter than 22.3(1.2 minutes in Group 1 and 18.8(1.1 in
Group 2
(p<0.05).
The sensory blockade at R4 dermatome in Group 6 were 74.0(3.8 min, which were longer than 52.9(2.4 minutes in Group 1 and 52.7(1.4 minutes in Group 2 (p<0.05). The duration of sensory blockade at L2 dermatome in Group 3 were 119.6(4.4 minutes,
which
were longer than 78.6(4.8 minutes in Group 1 and 81.6(2.5 minutes in Group 2 (p<0.05). the above results suggested that alkalinization of lidocaine solution is an effective way to shorten the latency and to prolong the duration of epidural block
for
cesarean section. (Korean J Anesthesiol 1995; 29: 106~111)
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