The influence of hyperbaric bupivacaine temperature on the spread of spinal anesthesia

The distribution of spinal anesthesia is affected by the density and viscosity of the local anesthetic solution that, in turn, may be influenced by the temperature of the injectate. Our hypothesis in the present study was that the temperature of the injectate influences its distribution into the subarachnoid space. We measured the density and viscosity of hyperbaric 0.5% bupivacaine at 25 degrees C and 37 degrees C and tested the onset and extent of spinal anesthesia achieved by these solutions in 36 patients. The densities of the two solutions were similar (mean [sd]): 25 degrees C, 1.028 [0.000], versus 37 degrees C, 1.028 [0.000] (g/mL), but the viscosity was more at 25 degrees C than at 37 degrees C (0.01116 [0.00003] versus 0.00843 [0.00002] g x cm(-1) x s(-1); P < 0.001). The maximum cephalad extent of loss of pinprick sensation was significantly higher with 37 degrees C (T2 with 37 degrees C versus T5 with 25 degrees C; P < 0.001), but the time to achieve peak block height was similar. In conclusion, we showed a consistent, but modest, increase in the cephalad level of spinal anesthesia by warming hyperbaric bupivacaine 0.5% from 25 degrees C to 37 degrees C. Viscosity was reduced in the warmed solution, but it is unclear if this or other factors led to the difference in spinal anesthetic level.     

The spread and time to two-segment regression of spinal anesthesia with 0.25% hyperbaric bupivacaine

The spread and time to two-segment regression of spinal anesthesia with 0.25% hyperbaric bupivacaine 2.0 ml (5 mg) were studied clinically in 20 patients for elective lower extremity, urological or gynecological surgery. Lumbar puncture was performed at the L 3-4 interspace with the patient in horizontal lateral decubitus positions using a 25-G Quincke needle. After injection of the local anesthetic solution at the rate of 0.2 ml.sec-1, the patient was placed immediately in supine position. Sensory block was assessed by using pinprick and motor block was assessed by using a four-point Bromage scale in every 5 min until 30 min, then every 10 min thereafter until two-segment regression of sensory block had recovered. Results were expressed as mean values +/- SD. Maximum sensory block level was Th 10.6 +/- 2.3, and time to two-segment regression was 51.5 +/- 14.6 min. Complete motor block was observed in three out of twenty patients (15%). These results indicate that spinal anesthesia with 0.25% hyperbaric bupivacaine is useful for a short case, which dose not require motor block or is performed as day-care surgery.     

Effects of baricity and mass of bupivacaine solutions in spinal anesthesia

We studied the effects of three different solutions of bupivacaine, injected intrathecally. Each solution had a volume of 3 ml and differed from the others by its mass or its baricity. Sixty-five patients, divided into three groups, remained in the sitting position for one minute after injection of the tested solutions. Group 1 received 10 mg of hyperbaric bupivacaine, group 2 received 10 mg of isobaric bupivacaine and group 3 received 15 mg of isobaric bupivacaine. Groups 1 and 2 showed no statistical difference in maximal extension of analgesia (T 11 and T 10), nor in mean duration of analgesia (155 and 159 min.). The motor block was similar in both groups (score less than 2 using the Bromage scale 0-3). Group 3 had a higher level of maximal cephalad extension and a longer mean duration of analgesia (186 min.). The motor block was more pronounced after 30 min. (85% score 3) compared to the two other groups. The decrease in mean arterial pressure was moderate and similar in the three groups. In view of the results of this study, we suggest the use of 3 ml of 0.5% isobaric bupivacaine injected intrathecally.     

Intravenous clonidine prolongs bupivacaine spinal anesthesia

BACKGROUND: Prolongation of spinal anesthesia by oral clonidine premedication has been known. We hypothesized that intravenous clonidine administered after the spinal block may prolong spinal anesthesia. METHODS: To assess the prolongation of spinal anesthesia by intravenous clonidine, we designed a double-blind, placebo-controlled, prospective study. Patients scheduled for orthopedic surgery received 12 mg of 0.5% hyperbaric bupivacaine and were randomly divided into three groups (n = 26 in each group). In the clonidine 10-min group, 3 microg x kg-1 of clonidine was administered for 10 min immediately after the spinal block. In the clonidine 60-min group, 3 microg x kg-1 of clonidine was administered for 10 min, 50 min after the spinal block. The control group received normal saline. Sensory block was evaluated by pinprick and the duration was defined as the time for sensory block to regress to L1 dermatome. Duration of motor block was defined as the time required for the patient to flex his or her knee. RESULTS: The duration of sensory block was longer in both the clonidine 10-min and clonidine 60-min groups compared with the control group (196 +/- 42 min, 179 +/- 41 min vs. 125 +/- 25 min, P < 0.05). The duration of motor block was longer in the clonidine 10-min group than in the control group (153 +/- 26 min vs. 131 +/- 29 min, P < 0.05). The lowest heart rate and mean blood pressure were not different among groups. CONCLUSIONS: Intravenous clonidine administration within 1 h after the spinal block prolonged bupivacaine spinal anesthesia for approximately 1 h without adverse effects.     

Plain or hyperbaric bupivacaine for spinal anesthesia

Three ml of bupivacaine 0.5%, either plain or in 8% glucose, was injected intrathecally in three groups of twenty patients. Group 1 received bupivacaine 0.5% plain; group 2 received bupivacaine 0.5% in 8% glucose. Patients in groups 1 and 2 were kept sitting for 3 min after injection. Patients in group 3 received bupivacaine 0.5% in 8% glucose and were placed in the supine horizontal position immediately after injection. Observations of patients in group 3 were observer blind and in groups 1 and 2 double blind. The differences between segmental levels of sensory and temperature loss between groups 1 and 2 and between groups 2 and 3 were statistically not significant. Motor blockade of the lower extremities was more intense in the patients who were kept sitting for 3 min (groups 1 and 2). It is concluded that both solutions are equally suitable for spinal anesthesia, provided patients receiving the plain solution are kept sitting for at least 2 min. When using hyperbaric bupivacaine, posture seems to have no influence on cephalad spread.     

A dose-response study of bupivacaine for spinal anesthesia

A randomized double-blind study was performed to elucidate the interrelationships among volume, concentration, and dosage of bupivacaine administered intrathecally. Sixty male patients between the ages of 40 and 80 years having transurethral surgery in the lithotomy position were studied using 10-, 15-, and 20-mg doses of glucose-free bupivacaine as either a 0.5 or a 0.75% solution. Success rate, time of onset and duration of anaglesia and motor block, and cardiovascular responses were assessed. It was found that both 15 and 20 mg of either concentration of bupivacaine provide satisfactory spinal anesthesia for transurethral urologic procedures. However, three of 20 patients receiving the 10-mg dose required supplementation with general anesthesia. Comparison of various volumes and concentrations of bupivacaine indicates that total dosage of bupivacaine is more important than volume or concentration. In several patients with sensory block involving cervical dermatomes, there was no significant hypotension or bradycardia, which suggests that cardiac output and venous return were maintained, perhaps because of the use of lithotomy position.     

Influence of injection speed of the spread of 4.0 ml of 0.5% isobaric bupivacaine in spinal anesthesia

Influence of injection speed on the spread of isobaric 0.5% bupivacaine 4.0 ml was studied in 100 patients to analyze the correlation between analgesia levels and patient's characteristics. All patients (ASA PS I.II) were scheduled for orthopedic or urological procedures, and received no premedication. They were randomly divided into two groups by injection speed; group 1 of 0.2 ml.sec-1 and group 2 of 0.03 ml.sec-1. Spinal tap was performed in lateral decubitus position at the L 3-4 intenspace with median approach, using a 25 G Quincke needle. Immediately after the injection, the patient was placed in supine position. The maximum sensory block was tested by pinprick method, and no significant difference in the height of sensory block was observed between the two groups. No significant correlation with patient's characteristics was observed except body weight in group 1. This study suggests that the speed of injection does not influence the spread of isobaric 0.5% bupivacaine 4.0 ml.     

Comparison between conventional and continuous spinal anesthesia using bupivacaine

A study was carried out to find out whether dividing the dose of local anaesthetic would give a better control of the spread and duration of sensory blockade due to spinal anaesthesia. It was carried out in 34 patients (mean age 62 years) scheduled for elective limb vascular surgery. All were classed ASA 2 or 3. Sensory blockade was assessed using a fine needle, and the degree of motor blockade with Bromage's scale. This was carried out every 5 min for the first 30 min, and thereafter, every 15 min until recovery from anaesthesia was complete. In the first group of patients (n = 16), spinal anaesthesia was obtained with a 26 gauge needle, the patient lying on his side; 4 ml of 0.5% bupivacaine were injected (1 ml every 10 seconds) before putting the patient supine. In the second group (n = 18), the catheter for continuous spinal anaesthesia was set up with the patient in the same position as for the first group. Once a length of 1 cm had been introduced in the subarachnoid space, the patient was placed supine and 2 ml of 0.5% bupivacaine were injected. If 15 min later sensory blockade did not reach T10, further 0.5 ml aliquots were given every 10 min so as to obtain a level of sensory blockade between T9 and T11. Maximum extension of sensory blockade was 15.1 +/- 2.3 metamers in group 1, with an extension to T3 in 2 patients. In group 2, 12.9 +/- 3.1 mg bupivacaine anaesthetized 14.2 +/- 1.9 metamers.(ABSTRACT TRUNCATED AT 250 WORDS)     

罗比卡因和布比卡因在老年人脊麻中的应用

目的比较罗比卡因和布比卡因在老年人脊麻中的应用。方法90例老年患者在脊麻下行择期经尿道前列腺电切术(TURP)或膀胱肿瘤电切术(TURBt)。按所用局麻药随机分为三组,每组30例。Ⅰ组用布比卡因12mg,Ⅱ组用罗比卡因12mg,Ⅲ组用罗比卡因15mg。观察感觉阻滞平面、运动阻滞程度、阻滞持续时间、麻醉效果及不良反应。结果Ⅱ组运动阻滞程度和感觉、运动阻滞持续时间明显低于其他两组(P<0.05),麻醉效果差于其他两组(P<0.05)。结论罗比卡因15mg与布比卡因12mg脊麻用于老年人TURP或TURBt,可达到比较安全而完善的麻醉效果。     

Influence of temperature of bupivacaine on spread of spinal analgesia

A prospective, randomised study was performed to investigate the influence of temperature on sensory blockade in spinal anaesthesia. Three ml of plain bupivacaine 0.5% were injected intrathecally at either 4 degrees C, room temperature, or 37 degrees C. There were 10 patients in each group, who were kept sitting for 2 minutes after injection. The maximum level of sensory blockade was significantly higher (p less than 0.01) in the group who received the solution adjusted to 37 degrees C, and variability of level was smaller (p less than 0.05). Time to two-segment regression was shorter in the 37 degrees C group than in the 4 degrees C group (p less than 0.05). Hypotension required administration of ephedrine more often in the 37 degrees C group (p less than 0.05). It is concluded that the use of plain bupivacaine 0.5% adjusted to 37 degrees C results in a higher and more predictable sensory blockade.     

Levobupivacaine versus racemic bupivacaine for spinal anesthesia.

Levobupivacaine is the pure S(-)-enantiomer of racemic bupivacaine but is less toxic to the heart and central nervous system. Although it has recently been introduced for routine obstetric and nonobstetric epidural anesthesia, comparative clinical studies on its intrathecal administration are not available. We therefore performed this prospective randomized double-blinded study to evaluate the anesthetic potencies and hemodynamics of intrathecal levobupivacaine compared with racemic bupivacaine. Eighty patients undergoing elective hip replacement received either 3.5 mL levobupivacaine 0.5% isobaric or 3.5 mL bupivacaine 0.5% isobaric. Sensory blockade was verified with the pinprick test; motor blockade was documented by using a modified Bromage score. Hemodynamic variables (e.g., blood pressure, heart rate, pulse oximetry) were also recorded. Intergroup differences between levobupivacaine and bupivacaine were insignificant both with regard to the onset time and the duration of sensory and motor blockade (11 +/- 6 versus 13 +/- 8 min; 10 +/- 7 versus 9 +/- 7 min; 228 +/- 77 versus 237 +/- 88 min; 280 +/- 84 versus 284 +/- 80 min). Both groups showed slight reductions in heart rate and mean arterial pressure, but there was no intergroup difference in hemodynamics. We conclude that intrathecal levobupivacaine is equal in efficacy to, but less toxic than, racemic bupivacaine. IMPLICATIONS: Levobupivacaine, the pure S(-)-enantiomer of racemic bupivacaine is an equally effective local anesthetic for spinal anesthesia compared with racemic bupivacaine.     

Ventilatory responses to hypercapnia during bupivacaine spinal anesthesia

The effect of spinal anesthesia with isobaric 0.5% bupivacaine on ventilatory responsiveness to CO2 rebreathing was studied in ten unpremedicated patients. Minute ventilation (VE) at end-tidal PCO2 = 55 mm Hg increased from 18.7 +/- 6.7 L/min (mean +/- SD) to 22.3 +/- 10.1 L/min after induction of spinal anesthesia (P less than 0.05). Occlusion pressure (P0.1) at PCO2 = 55 mm Hg also increased, from 3.8 +/- 1.5 to 5.0 +/- 1.7 cm H2O (P less than 0.05). Spinal anesthesia was not associated with significant changes in vital capacity, maximal inspiratory pressure, resting end-tidal PCO2, or the slopes or intercepts of the lines relating VE or P0.1 to PCO2. These results show an increased ventilatory responsiveness to CO2 with bupivacaine spinal anesthesia.     

Hyperbaric bupivacaine for spinal anesthesia in cesarean section

The efficacy and safety of 0.5% hyperbaric bupivacaine (Sensorcaine, Astra) was evaluated in 22 patients undergoing elective cesarean section under spinal anesthesia. The dose varied from 7.5 to 10 mg, (depending on the patient's height) which was significantly lower than previously reported. Patients were placed in head-down tilt immediately after subarachnoid injection. The mean spread of analgesia was to T3, which was reached in 10-15 min. Regression was complete in 258 +/- 16 min. Complete motor paralysis of lower extremities occurred in only two patients. Complete recovery of motor function in all patients was evident in less than 2.5 h. All infants were vigorous at birth and there were no serious maternal complications. The incidence of hypotension was 4.5%, the lowest reported as a consequence of spinal anesthesia in this group of patients. A technique involving the use of reduced doses of hyperbaric bupivacaine (0.5%) in conjunction with head-down tilt appears to be useful for spinal anesthesia for cesarean section.     

Unilateral bupivacaine spinal anesthesia for outpatient knee arthroscopy

PURPOSE: To compare unilateral and conventional bilateral bupivacaine spinal block in outpatients undergoing knee arthroscopy. METHODS: One hundred healthy, premedicated patients randomly received conventional bilateral (n = 50) or unilateral (n = 50) spinal anesthesia with 8 mg hyperbaric bupivacaine 0.5%. A lateral decubitus position after spinal injection was maintained in unilateral group for 15 min. Times from spinal injection to readiness for surgery, block resolution, and home discharge were recorded. RESULTS: Three patients in each group were excluded due to failed block. Readiness for surgery required 13 min (5 - 25 min) with bilateral and 16 min (15 - 30) with unilateral spinal block (P = 0.0005). Sensory and motor blocks on the operated limb were T9 (T12 - T2) with a Bromage score 0/1/2/3: 0/2/0/45 in the unilateral group and T7 (T12 - T1) with Bromage score 0/1/2/3: 4/1/6/36 with bilateral block(P = 0.026 and P = 0.016, respectively). Vasopressor was required only in five bilateral patients (P = 0.02). Two segment regression of sensory level and home discharge required 81+/-25 min and 281+/-83 min with bilateral block, and 99+/-28 min and 264+/-95 min with unilateral block (P = 0.002 and P = 0.90, respectively). CONCLUSION: Seeking unilateral distribution of spinal anesthesia provided more profound and longer lasting block in the operated limb, less cardiovascular effects, and similar home discharge compared with bilateral spinal anesthesia, with only a slight delay in preparation time.