Low dose of lidocaine: comparison of 15 with 20 mg/ml with dextrose for spinal anesthesia in lithotomy position and ambulatory surgery.

BACKGROUND: Spinal anesthesia with the local anesthetic lidocaine has come under scrutiny because it is associated with transient neurologic symptoms (TNS). Although TNS is not associated with either lidocaine concentration or dose, its incidence has never been examined with very small doses of hyperbaric spinal lidocaine in patients in the lithotomy position. We designed this study prospectively to compare the efficacy of low-dose 15 mg/ml with low-dose 20 mg/ml hyperbaric lidocaine in patients undergoing elective outpatient surgery in the lithotomy position. METHODS: A total of 100 patients were randomized to receive either 30 mg of 15 mg/ml or the same dose of 20 mg/ml hyperbaric lidocaine. Lidocaine density at 37 degrees C is 1.0241 g/ml for the 15 mg/ml and 1.0260 g/ml for the 20 mg/ml solution. Patients were examined for motor block, sensory block, and block duration. Patients were contacted at 24, 48 and 72 h and questioned about their perceptions of pain after the spinal anesthesia with specific questions designed to diagnose TNS. RESULTS: The spread of analgesia was the same with both solutions of lidocaine. Motor block was incomplete in all patients in both groups. TNS were not observed when low doses of both solutions of lidocaine with dextrose were used in these ambulatory patients in the lithotomy position. CONCLUSION: Hyperbaric lidocaine results in rapid recovery from sensory block and motor blockade. It may have advantages for patients in a day-case setting. No patients complained of TNS after discharge.

Selective sensory spinal anaesthesia with hypobaric lidocaine for anorectal surgery.

BACKGROUND: Lidocaine has been used for spinal anaesthesia since 1948, seemingly without causing concern until recently. This study aimed at evaluating the feasibility of performing anorectal surgery in outpatient settings with low hypobaric lidocaine doses. METHODS: Three groups of 50 patients, physical status ASA I-II, undergoing anorectal surgical procedures in a prone jack-knife position, received 3 ml (18 mg), 4 ml (24 mg) or 5 ml (30 mg) of hypobaric 0.6% lidocaine. Sensory and motor blockade, time until first urination, ambulation, complications and the need for analgesics were evaluated. Patients were followed until the third post-operative day. RESULTS: Adequate sensory block was obtained in all patients. Blockade was significantly lower in Group 1. The level at 15 min was L(1) with 3 ml, T(11) with 4 ml and T(10) with 5 ml. Only 24 patients presented a moderate motor block. There was no hypotension, nausea or vomiting, urine retention, transitory neurological symptom or post-dural puncture headache in any patients. There was one case of bradycardia with 4 ml and two cases with 5 ml. CONCLUSIONS: Hypobaric lidocaine predominantly provided a sensory block after injection in the prone jack-knife position. The smallest dose (3 ml=18 mg) provides sufficient analgesia with a lesser dispersion and a shorter duration. The major advantages were haemodynamic stability and a high degree of patient satisfaction.

A randomised, double-blind comparison of three different volumes of hypobaric intrathecal bupivacaine for orthopaedic surgery.

This study was designed to evaluate different doses of hypobaric 0.15% bupivacaine administered to achieve unilateral orthopaedic surgery under subarachnoid block. Using a randomised, double-blinded protocol, 150 ASA I to II patients scheduled for elective unilateral orthopaedic surgery were allocated to received a subarachnoid block with hypobaric bupivacaine 0.15% 4.5 mg (3 ml) (Group 1), 6.0 mg (4 ml) (Group 2) or 7.5 mg (5 ml) (Group 3). Measurements included cardiovascular and haemodynamic stability, incidence of unilateral anaesthesia, time to recover from motor block, postoperative urinary retention, transitory neurological symptoms and postdural puncture headache. There was a dose-dependent increase in the duration of the block, from 1:55 +/- 00:20 hours (4.5 mg) to 2:15 +/- 00:22 hours (6.0 mg) and 3:15 +/- 00:31 hours (7.5 mg). The sensory block in the operated limb was significantly higher than that in the non-operated limb at all times. The increasing dose resulted in an increase of the motor block score. Seventy percent of patients had unilateral block. It was concluded that the spinal anaesthesia in all groups was suitable for single limb orthopaedic surgery. The smallest dose (4.5 mg) of hypobaric 0.15% bupivacaine resulted in more unilateral blocks, with narrower distribution and shorter duration.