Onset of spinal block is more rapid with isobaric than hyperbaric bupivacaine

PURPOSE: To compare isobaric with hyperbaric 9.75 mg bupivacaine injected intrathecally, and to evaluate the effects of subsequent injection of lidocaine 2% into the epidural space. METHODS: Patients in group 1 (n = 30) received isobaric 9.75 mg bupivacaine and in group 2 (n = 30) hyperbaric 9.75 mg bupivacaine injected into the subarachnoid space in a combined spinal-epidural technique. They were undergoing urological, gynecological, orthopedic, gastro-intestinal or vascular surgery. Using a double blind technique, the followings parameters were measured: cutaneous analgesia to pinprick, motor blockade, time for two segment regression, time for complete regression of the motor block, quality of anesthesia. In 12 patients the effect of epidural injections of 3 ml lidocaine 2% was observed. RESULTS: Motor and sensory block developed more rapidly (five minutes) in the isobaric group (P<0.05). Maximum upper level (T7+/-2), two-segment regression (52 min in both groups), motor recovery (160 vs. 157 min), and quality of anesthesia did not differ between the two groups. Thirty nine epidural injections of 3 ml lidocaine 2% were given in 12 patients 10 min after spinal injection, 28 were in the hyperbaric group (P<0.05). Twenty six of the epidural injections produced an increase in sensory block of 0 or 1 dermatome, and 13, of 2 or more. CONCLUSION: The block developed more rapidly in the isobaric group, but both isobaric and hyperbaric 9.75 mg bupivacaine produced adequate upper levels of analgesia for surgery. The effect of epidural injections of 3 ml lidocaine 2% was usually minimal.     

The effect of baricity of intrathecal morphine in children receiving tetracaine spinal anaesthesia for cardiac surgery: a preliminary report

BACKGROUND: This prospective, randomized study examined the effect of baricity of intrathecal preservative-free morphine on the duration of postoperative analgesia and incidence of side-effects in infants and children receiving high spinal anaesthesia with hyperbaric tetracaine in combination with a light general anaesthetic. METHODS: Fourteen infants and children, aged 7-91 months, undergoing repair of either uncomplicated atrial or ventricular septal defects, were randomized to receive either 10 microg x kg(-1) of intrathecal morphine in combination with 0.5% tetracaine D10 (hyperbaric morphine group) or intrathecal morphine mixed with saline and injected sequentially after the administration of 0.5% tetracaine D10 (hypobaric morphine group). After spinal injection, patients were positioned in 30 degrees of Trendelenburg for a minimum of 10 min. Postoperatively, patients were monitored for a minimum of 12 h. Pain scores and the incidence and severity of side-effects were recorded every 1 h. RESULTS: All patients were extubated at the conclusion of surgery without any incidence of respiratory depression. There was a decreased incidence of vomiting in the hypobaric morphine group and no significant difference in the duration of analgesia. CONCLUSIONS: When intrathecal morphine is administered in conjunction with a hyperbaric tetracaine spinal to paediatric cardiac patients in the head down position, sequential administration of the hypobaric solution may mitigate side-effects.     

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.     

The effect of dexamethasone on postoperative pain and emesis after intrathecal neostigmine

We evaluated the effect of a single dose of dexamethasone on the incidence and severity of postoperative nausea and vomiting (PONV) after intrathecal injection of tetracaine plus neostigmine. Sixty ASA physical status I patients scheduled for inguinal herniorrhaphy were studied with a randomized, double-blinded, placebo-controlled protocol. The dexamethasone group (Group D) received 10 mg of dexamethasone IV before performance of spinal anesthesia, whereas the placebo group (Group P) received saline. Spinal anesthesia was performed with intrathecal injection of 15 mg tetracaine plus neostigmine 100 microg in both groups. Pain, PONV, and other side effects were evaluated 24 h after surgery. The duration and severity of analgesia and the incidence of PONV were not significantly different between the two groups. Our results demonstrate that a single dose of dexamethasone (10 mg) did not potentiate the analgesic effect or reduce the incidence of PONV after intrathecal injection of tetracaine and neostigmine. Implications: The results of our evaluation of the effect of IV dexamethasone versus saline control on analgesia and nausea and vomiting after intrathecal neostigmine and tetracaine suggest that IV dexamethasone did not enhance the analgesic effect of neostigmine or reduce the incidence of emesis after intrathecal administration.     

Influence of the baricity of a local anaesthetic agent on sedation with propofol during spinal anaesthesia

Background: This study examined the effect of different levels of spinalanaesthesia, induced by solutions of different baricity butcontaining the same amount of local anaesthetic agent, on therequirement for sedation with propofol. Methods: Thirty-six patients undergoing varicose vein surgery under spinalanaesthesia were randomly allocated to receive tetracaine 15mg in 3 ml of either glucose 5% (hyperbaric) or CSF (isobaric).I.V. propofol was started 5 min after the intrathecal injectionand was titrated to maintain a bispectral index (BIS) scoreof 65–75. The propofol requirements to maintain this rangein the two groups were compared every 5 min. Results: The propofol requirement was always lower in the hyperbaricgroup, with the differences becoming statistically significant20 min after the intrathecal injection. Total consumption ofpropofol over the 55 min of the study was also less in the hyperbaricgroup. Conclusion: The known difference in level of spinal anaesthetic block inducedby solutions of different baricity, but the same dose of localanaesthetic, was associated with different requirements forpropofol sedation as determined by BIS assessment.     

Prolongation of tetracaine spinal anesthesia by oral clonidine.

The effects of oral clonidine on the duration of isobaric tetracaine spinal anesthesia were studied in 30 patients undergoing urologic procedures. All patients received 15 mg of tetracaine intrathecally in isobaric saline solution. Group 1 (n = 10) received 0.25 mg of oral triazolam; group 2 (n = 10) received 0.15 mg of oral clonidine; and group 3 (n = 10) received 0.25 mg of oral triazolam and 0.75 mg of intrathecal phenylephrine. In group 1, the times for two- and four-segment regression of the level of analgesia to pin-prick were 80 +/- 17 and 123 +/- 22 min, respectively (mean +/- SD). The corresponding values of those measurements were 170 +/- 27 and 273 +/- 48 min in group 2 and 175 +/- 34 and 273 +/- 68 min in group 3. All the regression times in groups 2 and 3 were significantly longer than those in group 1. Regression times were not different between groups 2 and 3. The authors conclude that prolongation of tetracaine sensory analgesia may be produced by premedication with 0.15 mg of oral clonidine. The prolongation is similar to that produced by intrathecal phenylephrine.     

The clinical use of small-dose tetracaine spinal anesthesia for transurethral prostatectomy

In a double-blinded study, we compared conventional dose tetracaine (8 mg), small-dose tetracaine (4 mg) with added fentanyl and epinephrine, and small-dose tetracaine (4 mg) with added fentanyl subarachnoid anesthesia. Forty-five patients scheduled for transurethral resection of prostate (TURP) under subarachnoid anesthesia were randomly assigned to Group 1 (8 mg hyperbaric tetracaine), Group 2 (4 mg hyperbaric tetracaine, 10 microg fen-tanyl, and 0.2 mg epinephrine), and Group 3 (4 mg hyperbaric tetracaine, 10 microg fentanyl, and 0.2 mL saline). Evaluations were performed after spinal anesthesia. Subarachnoid block was successful in all patients except one in Group 1, who required general anesthesia by mask. The median peak sensory levels 10 min after the induction of spinal anesthesia in Group 1 was T8, which was significantly higher than Group 2 and Group 3 (P < 0.05). The time of sensory and motor recovery in Group 3 was less than in Groups 1 and 2 (P < 0.05). Hypotension was observed in four patients in Group 1 and none in Groups 2 and 3. We conclude that small-dose 4-mg hyperbaric tetracaine plus 10 microg fentanyl might provide adequate anesthesia and fewer side effects for TURP when compared with the conventional (8 mg) dose. IMPLICATIONS: Small-dose hyperbaric tetracaine (4 mg with 10 microg fentanyl added) may provide adequate anesthesia and fewer side effects for transurethral resection of the prostate.     

Effect of the lithotomy position on spinal anesthesia with hyperbaric tetracaine

This study was performed to determine the effects of lithotomy position on the spread of analgesia and hemodynamics following spinal anesthesia with 0.5% hyperbaric tetracaine. Thirty patients who underwent hysterectomy due to myoma uteri were studied. All patients received spinal anesthesia in the left lateral decubitus position and were turned supine immediately after intrathecal administration of the drug. Fifteen patients were then placed in the horizontal lithotomy position within 10 s, and the remaining 15 were kept in the horizontal supine position for 30 min. There were no significant differences between the groups in mean arterial pressure, heart rate, cardiac output, and in the cephalad spread of analgesia. The lithotomy position had no effect on the spread of analgesia or anesthetic course of spinal anesthesia with hyperbaric tetracaine.     

Causes and Prediction of Maldistribution during Continuous Spinal Anesthesia with Isobaric or Hyperbaric Bupivacaine

Background: Many cases of cauda equina syndrome after maldistribution of local anesthetics during continuous spinal anesthesia have been reported. In experiments, a caudad route of catheter travel and the use of hyperbaric agents have been shown to induce these limited blocks. The aim of this clinical study was to verify this hypothesis and seek a predictive factor for the maldistribution of bupivacaine.

Method: Continuous spinal anesthesia via a 19-gauge end port spinal catheter was performed in 80 elderly patients randomly assigned to receive either isobaric or hyperbaric solutions. Successive injections of 2.5 mg bupivacaine were performed at 5-min intervals until a sensory level at or cranial to T8 was obtained. Maldistribution was defined by a sensory level caudal to T12 despite a total dose of 17.5 mg of either isobaric or hyperbaric bupivacaine. After surgery, all catheters were injected with contrast media and examined radiographically.

Results: The frequency of maldistribution was not significantly different in the isobaric and hyperbaric groups. A caudally oriented catheter tip was found to be a major cause of maldistribution (P < 10-5). A thoracic sensory level could be reached in all patients presenting a limited block by simply changing the baricity of the bupivacaine, the position of the patient, or both. The sensory level obtained 10 min after the first injection of 2.5 mg isobaric or hyperbaric bupivacaine was found to be a predictive factor of maldistribution.     

Role of repeated epidural injections in preventing post-spinal hearing loss

Study ObjectiveTo determine if epidural volume extension and continued postoperative epidural injections prevent hearing loss associated with a 23-gauge (G) Quincke spinal needle.DesignProspective, double blinded trial.SettingOperating rooms.Patients30 adult patients scheduled for lower abdominal or perineal surgery during spinal anesthesia.InterventionsPatients were divided into two groups of 15 each. All patients received subarachnoid injection with a 23-G Quincke needle. While patients in Group S received a single-shot spinal, Group E patients underwent epidural catheter placement one intervertebral space above. The epidural catheter was bolused with 10 mL of normal saline followed by postoperative epidural boluses of local anesthetic for analgesia as needed.MeasurementsPatients’ auditory function was evaluated by pure tone audiometry (frequencies of 250-8,000 Hz) on the day before and two days after receiving the spinal anesthesia.Main ResultsUnilateral low-frequency hearing loss (500 Hz) was seen in Group S (P < 0.05). It was prevented by the repeated epidural injections as used in Group E.ConclusionFollowing spinal anesthesia, epidural volume extension with 10 mL of normal saline followed by epidural local anesthetic boluses titrated to adequate postoperative analgesia (6-8 mL each time) prevents post-spinal hearing loss.     

Effects of epidural injection on spinal block during combined spinal and epidural anesthesia for cesarean delivery

BACKGROUND AND OBJECTIVES: Epidural injection has been known to enhance spinal anesthesia in combined spinal and epidural (CSE) anesthesia. Saline and local anesthetics have been reported to have a volume effect, elevating sensory level when supplementing a volume into the epidural space. We evaluated the effects of epidural injection when using the CSE technique for cesarean delivery. METHODS: Sixty-six parturients were allocated randomly into group C (control, n = 21), S (saline, n = 21), or B (bupivacaine, n = 24): epidural injections of 10 mL saline and 0.25% bupivacaine were given in groups S and B, respectively, 10 minutes after they received 8 mg of 0.5% hyperbaric bupivacaine intrathecally, and no injection was given in group C. The sensory level at 10 minutes, the maximal level and the time to reach it, and degree of motor block and muscle relaxation were compared. We also investigated intraoperative side effects and postoperative findings in the postanesthesia care unit. RESULTS: Epidural injection raised the sensory level significantly in groups S and B, but the maximal height of sensory block and degree of muscle relaxation did not differ among the groups. Fewer patients complained of intraoperative pain in group B than in the other groups (P <.001). CONCLUSIONS: We could not achieve satisfactory surgical analgesia with 8 mg of hyperbaric bupivacaine injected into the subarachnoid space using the needle-through-needle technique in cesarean deliveries. An epidural saline injection elevated the sensory level, which did not improve the spinal block, whereas an epidural injection of 10 mL of 0.25% bupivacaine enhanced the spinal block and sustained the block postoperatively.     

Intrathecal Bupivacaine in Humans: Influence of Volume and Baricity of Solutions

Background: The effects of volume and baricity of spinal bupivacaine on block onset, height, duration, and hemodynamics were studied.

Methods: Ninety patients undergoing endoscopic urologic procedures were randomized to receive 10 mg of intrathecal bupivacaine at L2-L3 level in sitting position. In the operating room, commercial products were diluted as needed with NaCl 0.9% to obtain isobaric solutions (density, 1.005-1.008) or with NaCl 0.9% and glucose 30% to obtain hyperbaric solutions (density, 1.031-1.037) of 2, 5, or 10 ml (six groups of 15 patients each). Three minutes after spinal injection the patients were placed in lithotomy position. Sensory blockade was assessed using pinprick and cold sensation tests, and motor blockade was assessed using a four-point scale.

Results: Onset times to maximal cephalad spread of spinal blockade were similar with isobaric and hyperbaric solutions. A greater maximal cephalad spread of anesthesia was obtained with diluted isobaric bupivacaine but was not associated with more hypotension. Volume had no effect on cephalad extent of anesthesia with hyperbaric bupivacaine. Times for regression of anesthesia to L2 and offset of motor block were longer with isobaric than with hyperbaric solutions of bupivacaine. The intensity of motor blockade was decreased with diluted hyperbaric bupivacaine. No patient reported back pain.     

The effect of posture and baricity on the spread of intrathecal bupivacaine for elective cesarean delivery

Posture and baricity during induction of spinal anesthesia with intrathecal drugs are believed to be important in determining spread within the cerebrospinal fluid. In this double-blind prospective study, 150 patients undergoing elective cesarean delivery were randomized to receive a hyperbaric, isobaric, or hypobaric intrathecal solution of 10 mg bupivacaine during spinal anesthesia induced in either the sitting or right lateral position. After an intrathecal injection using a combined-spinal technique patients were placed in the supine wedged position. We determined the densities of the three intrathecal solutions from a previously validated formula and measured using a DMA-450 density meter. Data collection included sensory level, motor block, episodes of hypotension, and ephedrine use. Statistical analysis included analysis of variance and Cuzick's trend. In the lateral position, baricity had no effect on the spread of sensory levels for bupivacaine compared to the sitting position, where there was a statistically significant difference in spread with the hypobaric solution producing higher levels of analgesia than the hyperbaric solution (P = 0.002). However, the overall differences in maximal spread only differed by one dermatome, with the hyperbaric solution achieving a median maximum sensory level to T3 compared with T2 for the isobaric and hypobaric solutions. Motor block was significantly (P = 0.029) reduced with increasing baricity and this trend was significant (P = 0.033) for the lateral position only. Hypotension incidence and ephedrine use increased with decreasing baricity (P = 0.003 and 0.004 respectively), with the hypobaric sitting group having the most frequent incidence of hypotension (76%) as well as cervical blocks (24%; P = 0.032).     

Caesarean section to prevent supine hypotension syndrome

BACKGROUND: The objective of this study was to investigate the effects of posture after spinal anesthesia with 2% lidocaine and 0.5% isobaric bupivacaine in parturients undergoing caesarean section and to demonstrate our modified combined spinal epidural (CSE) method. METHODS: The patients in groups 2%lido (S) and (L) received 2 ml of 2% lidocaine and the patients in groups 0.5%bupi (S) and (L) received 1.6 ml of 0.5% isobaric bupivacaine. The two (S) groups were turned into the supine position after spinal injection and the two (L) groups were kept on their left side for 10 or 15 minutes before they turned supine. All the patients received an epidural injection of 6 ml of 2% lidocaine or 6 ml of 1% ropivacaine 16 minutes after spinal injection. RESULTS: There was a significant difference in the level of analgesia between the (S) groups and the (L) groups 10 minutes after spinal injection (P<0.05). The systolic blood pressures 10 minutes after spinal injection were significantly decreased than those before spinal injection in the (S)groups (P<0.05). CONCLUSIONS: Our modified CSE method can provide beneficial effects on full term pregnant women by preventing hypotension due to spinal anesthesia.     

The influence of baricity on differential blockade with 0.5% bupivacaine spinal anesthesia

We evaluated the influence of baricity on differential blockade during spinal anesthesia using isobaric or hyperbaric 0.5% bupivacaine. Forty ASA-PS I-II patients scheduled for elective surgery (orthopedic, lower abdominal and urologic) were divided into two groups; group H, using hyperbaric 0.5% bupivacaine, and group I, using isobaric 0.5% bupivacaine. Spinal anesthesia was performed in lateral decubitus position, using a 25-gauge Quincke needle at L2-3 interspace, and 0.5% bupivacaine 2.0 ml was injected for 10 seconds. Patients were turned to supine position soon after the spinal anesthesia and the block levels were examined every 5 min for 30 min. Sympathetic blockade was detected by observer's hand, the loss of cold sensation by alcohol sponge and the loss of pain sensation by pinprick. Complete motor blockade was detected by modified Bromage scale. Significant higher sensory blockade and large number of complete motor block were observed in group H. Differential blockade between sympathetic and sensory was significant and lasted 30 min in group I, but lasted only 15 min in group H.     

Isobaric and hyperbaric bupivacaine 0.5% solution for spinal anesthesia

The effects of spinal anesthesia with 0.5% isobaric and hyperbaric (8% glucose) bupivacaine were investigated in 45 patients who had lower limb or lower abdominal surgery. The patients were divided into 3 groups. Group 1 patients received 3 ml of 0.5% isobaric bupivacaine. The patients in group 2 and 3 received 3 or 2 ml of 0.5% hyperbaric bupivacaine (8% glucose). Blood pressure dropped in all groups. The decrease in blood pressure was so severe in group 2 that vasopressors were required in 70% of cases. The average segmental level of analgesia was T9 in group 1, C8 in group 2 and T4 in group 3. Complete motor blockade was obtained in all the patients. Time to complete motor blockade of the lower limbs was 12.6 min in group 1, 5.5 min in group 2 and 8.4 min in group 3. Duration of analgesia and motor blockade were 387.4 min and 303.7 min in group 1, 373.5 min and 300.0 min in group 2 and 318.9 min and 228.9 min in group 3. These results suggest that adequate surgical anaesthesia could be obtained with 3 ml of 0.5% isobaric bupivacaine and 2 ml of 0.5% hyperbaric bupivacaine.     

Does Spinal Anesthesia Result in a More Complete Sympathetic Block Than That from Epidural Anesthesia?

Background: Spinal and epidural injection of local anesthetics are used to produce sympathetic block to diagnose and treat certain chronic pain syndromes. It is not clear whether either form of regional anesthesia produces a complete sympathetic block. Spinal anesthesia using tetracaine has been reported to produce a decrease in plasma catecholamine concentrations. This has not been demonstrated for epidural anesthesia in humans with level of anesthesia below C8. One possible explanation is that spinal anesthesia results in a more complete sympathetic block than epidural anesthesia. To examine this question, a cross-over study was performed in young, healthy volunteers.

Methods: Ten subjects underwent both spinal and epidural anesthesia with lidocaine (plain) on the same day with complete recovery between blocks. By random assignment, spinal anesthesia and epidural anesthesia were induced via lumbar injection. Before and 30 min after local anesthetic injection, a cold pressor test (CPT) was performed. Blood was obtained to determine epinephrine and norepinephrine plasma concentrations at four stages: (1) 20 min after placing peripheral catheters, (2) at the end of a 2-min CPT (before conduction block), (3) 30 min after injection of epidural or spinal lidocaine, and (4) at the end of a second CPT (during anesthesia). Mean arterial pressure, heart rate, noninvasive cardiac index, and analgesia to pin-prick were monitored.

Results: Neither spinal nor epidural anesthesia changed baseline resting values of catecholamines or any hemodynamic variable, except heart rate, which was slightly decreased during spinal anesthesia. Median level of analgesia was T4 during spinal and T3 during epidural anesthesia. CPT before conduction block reliably increased heart rate, mean arterial pressure, cardiac index, epinephrine, and norepinephrine. Conduction block attenuated the increase in response to CPT only in mean arterial pressure (spinal and epidural) and cardiac index (spinal only). Neither technique blocked the increase in heart rate, norepinephrine, or epinephrine to CPT.     

Intrathecal bupivacaine in humans: influence of volume and baricity of solutions.

BACKGROUND: The effects of volume and baricity of spinal bupivacaine on block onset, height, duration, and hemodynamics were studied. METHODS: Ninety patients undergoing endoscopic urologic procedures were randomized to receive 10 mg of intrathecal bupivacaine at L2-L3 level in sitting position. In the operating room, commercial products were diluted as needed with NaCl 0.9% to obtain isobaric solutions (density, 1.005-1.008) or with NaC 10.9% and glucose 30% to obtain hyperbaric solutions (density, 1.031-1.037) of 2, 5, or 10 ml (six groups of 15 patients each). Three minutes after spinal injection the patients were placed in lithotomy position. Sensory blockade was assessed using pinprick and cold sensation tests, and motor blockade was assessed using a four-point scale. RESULTS: Onset times to maximal cephalad spread of spinal blockade were similar with isobaric and hyperbaric solutions. A greater maximal cephalad spread of anesthesia was obtained with diluted isobaric bupivacaine but was not associated with more hypotension. Volume had no effect on cephalad extent of anesthesia with hyperbaric bupivacaine. Times for regression of anesthesia to L2 and offset of motor block were longer with isobaric than with hyperbaric solutions of bupivacaine. The intensity of motor blockade was decreased with diluted hyperbaric bupivacaine. No patient reported back pain. CONCLUSION: In this study, volume had no significant influence on either cephalad spread or duration of sensory blockade for either isobaric or hyperbaric bupivacaine. Time for offset of anesthesia was shorter with hyperbaric bupivacaine compared with isobaric solutions.     

A randomized comparison of onset of anesthesia between spinal bupivacaine 5 mg with immediate epidural 2% lidocaine 5 mL and bupivacaine 10 mg for cesarean delivery

BackgroundPrevious studies using low-dose spinal anesthesia for cesarean delivery have focused on hypotension and efficacy. This study evaluated whether, using a combined spinal–epidural technique, there was a difference in onset of anesthesia for cesarean delivery between low-dose spinal with an immediate epidural local anesthetic bolus, and conventional-dose spinal anesthesia.MethodsForty healthy term nulliparous women undergoing elective cesarean delivery with a combined spinal–epidural technique were enrolled into this prospective, randomized, double-blind study. Patients were randomly allocated to the low-dose (Group L) or conventional-dose group (Group C). Patients in Group L received intrathecal isobaric bupivacaine 5 mg with sufentanil 2.5 μg followed by epidural 2% lidocaine 5 mL; patients in Group C received intrathecal isobaric bupivacaine 10 mg with sufentanil 2.5 μg followed by epidural saline 5 mL. The onset of anesthesia (defined as the time from spinal injection to a block to T6), incidence of hypotension, maximal sensory block, epidural supplementation and side effects were recorded.ResultsAll blocks reached T6 within 11 min except for one patient in Group L. There were no differences in onset of anesthesia (9.9 ± 3.2 min in Group L vs. 8.5 ± 1.2 min in Group C, P = 0.08), maximal block level and the number of patients who required epidural supplementation in both groups. Hypotension occurred in 8 patients (40%) in Group L and 15 patients (75%) in Group C (P = 0.02).ConclusionsIntrathecal bupivacaine 5 mg with immediate 2% epidural lidocaine 5 mL provided comparable onset and efficacy of anesthesia as bupivacaine 10 mg with immediate epidural normal saline 5 mL for cesarean delivery.     

Sensory block extension during combined spinal and epidural

Background and Objectives. During a combined spinal and epidural technique, extension of sensory block by epidural injection of saline or bupivacaine has been demonstrated and attributed to a volume effect or to the combination of a volume effect with a local anesthetic effect. This two-part study was designed to evaluate the time dependency of the volume effect and the local anesthetic effect on the mechanism of spinal block extension. Methods. We performed two prospective studies. Thirty patients were randomized in each study. A combined spinal and epidural was performed in a sitting position in all groups. The patients in the first study received 15 mg hyperbaric bupivacaine intrathecally and were placed supine 2 minutes after spinal injection. They received 10 mL epidural saline either 5 minutes after spinal (group A) or 20 minutes after spinal (group B) compared to a control group (group C). The patients in the second study received 12.5 mg hyperbaric bupivacaine intrathecally and were placed supine 5 minutes after spinal injection. They then received epidurally either 10 mL saline 7 minutes after spinal (group D) or 10 mL bupivacaine 7 minutes after spinal (group E) or nothing (group F). Sensory block levels were assessed by a loss of sensation to cold using ether. Results. In the first portion of this study, in group A, area under the curve of sensory block levels by time from 10 to 40 minutes after spinal injection, and maximum sensory block levels were significantly higher (P < .05) compared to groups B and C. In the second portion of the study, sensory block levels were comparable at all times in the three groups. Conclusions. During a combined spinal and epidural technique with the use of hyperbaric bupivacaine, the volume effect is time dependent and is seen when epidural top up is done soon after spinal injection. This volume effect is abolished when patients are left seated for 5 minutes after spinal injection. The local anesthetic effect is not demonstrated when high sensory block levels are achieved by spinal injection.