Spinal anaesthesia with glucose–free 2% lignocaine. Effect of different volumes

Spinal anaesthesia with 2, 3 or 4 ml of glucose-free 2% lignocaine was studied in 64 patients undergoing transurethral surgery of the bladder. Cephalad spread of analgesia, onset time, duration of analgesia, duration of motor block, quality of analgesia, and the cardiovascular effects were assessed. Two ml of 2% lignocaine was insufficient to produce reliable analgesia. Three ml provided sufficient analgesia in most of the patients, but 4 ml was needed to guarantee sufficient analgesia in all patients. Onset times for analgesia and motor block were 10-20 min. After 4 ml the median and interquartile values were: maximum cephalad spread: T8, (T10-T5); time from injection to regression of analgesia to T11: 84 min, (60-103 min); duration of complete motor block: 90 min, (60-120 min). All patients in the 3-ml and 4-ml groups developed complete motor block. There was a positive correlation between the dose and the duration of analgesia and motor block. A positive correlation, although weaker, was also seen between the dose and the maximum cephalad spread of analgesia. There was an inverse relationship between the cephalad spread of analgesia and the duration of motor block. Falls in systolic blood pressure greater than 30% were noted in seven patients in whom the cephalad spread of analgesia was higher than in the rest of the patients. Spinal anaesthesia with glucose-free 2% lignocaine in doses of 3-4 ml provides reliable analgesia for transurethral surgery of the bladder.     

A comparison of glucose-free 2% lidocaine and hyperbaric 5% lidocaine for spinal anaesthesia

Fifty patients scheduled to undergo transurethral surgery of the bladder were allocated to receive spinal anaesthesia with either glucose-free 2% lidocaine (80 mg) or hyperbaric 5% lidocaine (80 mg). Onset time, cephalad spread of analgesia, duration of analgesia, duration and intensity of motor block, quality of analgesia, and the patients' ability to walk 5 m and to micturate postoperatively were assessed. Onset and spread of analgesia were fast and comparable in the two groups. At 60 min, the median segmental level of analgesia was T9 and T10 for the 2% and the 5% group, respectively, allowing transurethral surgery to be performed for at least 1 h. In the 2% group the motor block was more pronounced and longer lasting than in the 5% group. Two patients in the 5% group needed general anaesthesia because of pain. The time from injection of the spinal anaesthetic until the patients were able to walk 5 m and to micturate was equal in the two groups, and 89% of all the patients were able to walk and micturate within 4 h. It is concluded that spinal anaesthesia with 80 mg and 2% or 5% lidocaine provides analgesia for transurethral surgery and is characterized by fast recovery of motor and detrusor function.     

Effects of volume and concentration of lidocaine on epidural anaesthesia in pregnant females

BACKGROUND AND OBJECTIVE: The effects of altering the concentration of a local anaesthetic on the development of epidural anaesthesia in pregnant females are unclear. We compared the anaesthetic effects of a constant dose of two different concentrations of epidural lidocaine for Caesarean section. METHODS: After Institutional Review Board approval and informed consent, patients undergoing elective Caesarean section were randomized to receive either lidocaine 1% 30 mL (+epinephrine 5 microg mL(-1)) or lidocaine 2% 15 mL (+epinephrine 5 microg mL(-1)) (n = 20 each) for epidural anaesthesia at the L1-L2 interspace. The spread of the sensory block to pinprick and the degree of motor block (modified Bromage scale) were measured at 5, 10, 15, 20 and 30 min after injection. RESULTS: No significant differences in the progression of analgesia and motor block were observed at any time between 1 and 2% lidocaine. The maximum cephalad spread was observed 30 min after injection; the median was at T4 (range T3-T5) and at T4 (range T3-T6) for lidocaine 1 and 2%, respectively. CONCLUSIONS: The same doses but different volumes of lidocaine 1 and 2% produced comparable anaesthetic effects in pregnant females. The effects of epidural anaesthesia depend primarily on the total dose of the local anaesthetic.     

Spinal Anaesthesia with Hyperbaric 0.5 % Bupivacaine: Effects of Volume

Different volumes (1.5, 2, 3 and 4 ml) of hyperbaric 0.5% bupivacaine (8% glucose) were compared in spinal anaesthesia for urological surgery in 40 patients. The blockade was given with the patient in the sitting position. Two minutes after the injection the patient was placed in the lithotomy position. The time required for maximum cephalad spread of analgesia was about 20 min for all volumes. The maximum cephalad spread was directly related to log volume of the local anaesthetic solution. The onset time for motor blockade of the lower limbs decreased and the frequency increased with increasing volume. Four ml produced complete blockade in all patients. The duration of analgesia increased with increasing volume: 3-4 ml produced analgesia at T8 for 1.5-2.5 h and at L1 for 2-3 h. With this volume, complete motor blockade was obtained for 1.5-2.5 h. Satisfactory surgical anaesthesia for transurethral resection was obtained with 3-4 ml of the local anaesthetic solution.     

Spinal anesthesia with bupivacaine for surgery of the hip in the elderly

In 60 elderly patients, spinal anaesthesia for orthopaedic hip surgery was induced randomly with 15 mg bupivacaine 0.375% without glucose (Group I), 2.5% glucose (Group II) or 7.5% glucose (Group III), in 4 ml. The injection was made in the lateral position, and the patients turned supine immediately after. The onset, extent and duration of sensory and motor blockade, the cardiovascular effects and the quality of anaesthesia were evaluated. The hyperbaric solutions produced a greater cephalad spread of analgesia (T8,9 and T9,8 respectively) than the glucose-free solution (T10,5). The mean duration of analgesia at the L2 level with the isobaric solution was significantly greater: 187 min versus 171 min and 150 min with the hyperbaric solutions. All the patients had complete motor blockade of the lower limb. The mean duration of the motor block was significantly shorter for the 2.5% and 7.5% glucose solutions (137 and 125 min respectively for Bromage's degree 3) versus 170 min for the glucose-free solution. Although the pre-anaesthetic arterial pressures in the three groups did not differ significantly, the systolic, mean and diastolic arterial pressures decreased only by about 20 to 25% in all groups. It was suggested to take into account the more rapid infusion of lactated Ringer's solution (20 ml X kg-1) in Group III. Anaesthesia was satisfactory in 95% of patients in Group I and Group II, and 90% in Group III. Glucose-free bupivacaine produced a long-lasting blockade suitable for hip surgery of long duration.     

Spinal anaesthesia with 0.25% hyperbaric bupivacaine for Caesarean section: effects of volume

To investigate the safety and efficacy of 0.25% hyperbaric bupivacaine for spinal anaesthesia in Caesarean section, we studied 60 parturients allocated randomly to one of three groups. According to the patient's height, groups 1, 2 and 3 received 3.2-3.6 ml (8-9 mg), 3.6-4.0 ml (9- 10 mg) and 4.0-4.4 ml (10-11 mg) of 0.25% bupivacaine in 5% glucose, respectively. Subarachnoid injection was performed in the right lateral decubitus position, and parturients were then turned immediately supine with left uterine displacement. Mean spread of sensory analgesia was significantly higher in group 3 (T2-3) than in groups 1 and 2 (T4-5 in each group). Duration of sensory analgesia was significantly longer in groups 2 and 3 than in group 1. Complete motor block of the lower extremities occurred in all patients but in only one in group 1. Onset time and duration of motor block were not significantly different between the three groups. The incidence of hypotension was significantly higher in group 3 (75%) than in groups 1 and 2 (40% in each group). The efficacy of intraoperative analgesia was significantly greater in groups 2 and 3 than in group 1. The incidence of patients requiring analgesics during operation was significantly lower in groups 2 (25%) and 3 (10%) than in group 1 (70%). There was no difference in neonatal condition between the three groups. Spinal anaesthesia with 3.6-4.0 ml of 0.25% bupivacaine in 5% glucose was satisfactory for Caesarean section.      

SPINAL ANAESTHESIA WITH 0.75% BUPIVACAINE AND 0.5% AMETHOCAINE IN 5% GLUCOSE

Three millititre of 0.75% plain bupivacaine and 0.5% amethocaine3 ml in 5% glucose were used for spinal anaesthesia and comparedin a double-blind study of 20 patients undergoing urologicalsurgery. The onset time to maximum cephalad spread of sensoryanalgesia was approximately 45 min for bupivacaine and approximately30 min in the amethocaine group (ns). The mean maximum spreadof sensory analgesia was similar for both agents: T6-7 180 minafter injection, although the cephalad spread of sensory analgesiawith bupivacaine persisted for longer at a significantly higherlevel than that of amethocaine. Duration of sensory analgesiawas significantly longer in the bupivacaine group from S3 toS5 and from T12 to L2 levels. Onset time to complete motor blockadeof the lower limbs was similar for both agents. Nine of 10 bupivacainepatients and seven of the 10 patients receiving amethocainehad complete motor blockade of the lower limbs. Duration ofmotor blockade was significantly longer for all degrees in thebupivacaine group.     

Spread of spinal anaesthesia using various doses of plain 0.5 % bupivacaine injected at the LIV—V interspace

Spinal anaesthesia with 3 ml, 4 ml or 5 ml of plain 0.5% bupivacaine was performed in three groups of 20 orthopaedic (ASA 1) patients at the LIV-V interspace. Patients aged less than 20 years or more than 60 years and those outside the normal range of body mass index were excluded. The spread of analgesia was greater in the 4-ml and 5-ml groups compared to the 3-ml group at each testing time (P less than 0.05). The mean maximum cephalad spread of pinprick analgesia (+/- s.d.) 60 min after injection was significantly higher (P less than 0.05) in the 4-ml group (T10 +/- 3.2) and in the 5-ml group (T10 +/- 2.7) than in the 3-ml group (T12 +/- 2.1). The interindividual variability of the cephalad spread of analgesia was greater in the 4-ml and 5-ml groups compared to the 3-ml group (P less than 0.05). The degree of motor block was higher in the 5-ml group than in the 3- and 4-ml groups at 5 and 15 min after injection. In seven patients the first sign of motor block was the patient's inability to flex the ankle, rather than inability to raise an extended leg as was the case in the other patients. In all patients satisfactory anaesthesia for surgery of the lower extremity was achieved.     

Alkalinization improves the quality of lidocaine-fentanyl epidural anaesthesia for Caesarean section

This double-blind randomized study of 116 healthy women was undertaken to evaluate whether alkalinization potentiated the analgesic effects of epidural fentanyl-lidocaine for elective Caesarean section. After a test-dose of 3 ml, lidocaine 2% with adrenaline 1:200,000, all patients received 100 μg, fentanyl in 5 ml saline and they were then divided into two groups, to receive incremental doses of 5 ml lidocaine 2% with adrenaline 1:200,000 with or without 0.1 mEq · ml^?1 sodium bicarbonate, to obtain anaesthesia to T₄. The addition of bicarbonate to lidocaine resulted in a mean (SD)pH increase from 6.58 (0.01) to 7.14 (0.02) and in a mean PCO₂ increase from 3.8 (0.8) to 345.1 (5.9) mmHg. Onset of sensory analgesia to the S₁ segment as well as the interval between the block and the delivery of the baby were shorter in the bicarbonate group (respectively 15.4 (6.9) vs 18.9 (4.8) min and 28.9 (9.5) versus 33.9 (11.8) min; P < 0.01 and 0.05). No differences were noted in the onset to T₄ or in the degree of motor block. The percentage of patients experiencing pain during surgery and requiring intravenous analgesics was higher in the group which did not receive bicarbonate (3% vs 16%; P < 0.05). There were no differences in intraoperative maternal side-effects, neonatal outcome or in maternal venous and umbilical venous and arterial lidocaine concentrations between the groups. The concentrations of fentanyl in maternal plasma, umbilical artery, and the umbilical artery to maternal vein ratio were greater in the alkalinized group (P < 0.001). In conclusion, alkalinization improves the quality and reliability of epidural anaesthesia provided with fentanyl and lidocaine for Caesarean section in healthy mothers.     

Ropivacain zur Spinalanästhesie Eine Dosisfindungsstudie

Several clinical studies have demonstrated the efficacy of ropivacaine in different regional anaesthesia techniques, e.g., epidural anaesthesia. However, the efficacy of ropivacaine for spinal anaesthesia has only been demonstrated in animal experiments up to now. The objective of this study was the investigation of the efficacy and appropriate dosage of isobaric ropivacaine for spinal anaesthesia in humans. Methods. In a randomised, double-blind study, spinal anaesthesia with ropivacaine was performed in two groups of 20 patients each (group I: ropivacaine 0.5%, 3?ml=15?mg; group II: ropivacaine 0.75%, 3?ml=22.5?mg). Spinal anaesthesia was performed with a 25?G needle in the midline at the L3–4 level with the patient sitting up, preceded by local infiltration of 2?ml mepivacaine 0.5%. Spread and regression of sensory block were assessed by testing loss of sensation to cold. Development of motor block was concurrently recorded by means of a modified Bromage scale (motor block was assessed in the hip, knee and ankle joints and recorded as complete or incomplete according to degree). The findings are presented as mean values. Results. Onset of analgesia to L5 and S1 was 2?min in both groups, and to T12 and T10 8 and 12.5?min, respectively, in group I and 12.5 and 13?min, respectively, in group II; these differences were not statistically significant. Mean maximum spread was to T10 in group I and T8 in group II. Onset of maximum cranial spread was 24?min in group I and 32?min in group II. Duration of analgesia in the segments relevant to the performed operations varied in group I between 1.5 and 5.7?h (S3 4.9, S1 5.7, L4 5.4, L2 3.0, T12 2.0, T10 1.6, T8 1.5?h) and in group II between 1.8 and 5.9?h (S3 5.4, S1 5.9, L4 5.7, L2 4.1, T12 2.9, T10 2.3, T8 1.8?h). These differences were significant in the segments S3, L3, L2, L1, T12, and T10. In 5 patients (20%) in group I adequate analgesia for the planned surgical intervention was not obtained. In 4 of these 5 patients the required spread of the spinal block was not reached; in 2 general anaesthesia had to be performed and in 2 the required analgesia could be obtained by administration of an analgesic (fentanyl). In the 5th patient the level of spinal block was sufficient for the planned operation, however, the quality of analgesia was not, i.e., additional analgesics were required. In the group that received the 0.75% solution additive analgesics were necessary in 1 patient (5%) because a sufficient level of anaesthesia for the planned operation was not obtained. In group I all patients had a complete motor block in all three joints (hip, knee, and ankle); in group II, however, the motor block was incomplete in 6 patients. This difference between the 2 groups was statistically significant. Onset of motor block of hip, knee, and ankle joints occurred after 10, 15, and 15?min, respectively, in group I and 10, 12, and 15?min, respectively, in group II. These differences were not statistically significant. Duration of motor block in the three joints was significantly longer (3.4, 2.8, and 3.8?h)in group II than in group I (2.4, 1.9, 2.7?h). Statistically significant changes in systolic and diastolic blood pressures (BP) and heart rate (HR) were recorded in both groups in the course of the study period. Relative BP changes were assessed in the individual patients. There were no statistically significant changes between the two groups with regard to relative changes in systolic and diastolic BP and HR. Bradycardia occurred a total of 13 times in 10 patients in group I and in 11 patients in group II. A BP decrease of >20% was measured in 1 patient in each group. Twelve of the 40 patients complained a headache in the first 6 days; in this respect the groups did not differ significantly. There was no difference between male and female patients with regard to side effect profile. Conclusion. At concentrations of 0.5% and 0.75%, ropivacaine results in long-lasting spinal anaesthesia. Duration of analgesia as well as duration and degree of motor block increase with the higher concentration. Neurotoxic effects of the local anaesthetic were not observed. A dose of 3?ml ropivacaine 0.75% seemed to be suitable for the gynaecologic and urologic operations (Table?3) with regard to efficacy of analgesia and local anaesthetic spread.     

Extension of epidural blockade in labour for emergency Caesarean section using 2% lidocaine with epinephrine and fentanyl, with or without alkalinisation

In a randomised, double-blind study, we investigated rapid extension of epidural analgesia to surgical anaesthesia for emergency Caesarean section. Parturients receiving epidural analgesia in labour who subsequently required Caesarean section were given a test dose of 3 ml lidocaine 2% with epinephrine 1 : 200 000, followed 3 min later by 12 ml lidocaine 2% with epinephrine 1 : 200 000 and fentanyl 75 microg, to which was added 1.2 ml sodium bicarbonate 8.4% (bicarbonate group; n = 20) or saline (saline group; n = 20). Mean (SD [range]) time to surgical anaesthesia was less in the bicarbonate group (5.2 (1.5) [2-8] min) than the saline group (9.7 (1.6) [6-12] min; mean difference 4.5 min (95% CI 3.5-5.5) min; p < 0.001). Maternal side-effects and neonatal outcome were similar between groups. We conclude that pH-adjusted lidocaine 2% with epinephrine and fentanyl is effective for rapidly establishing surgical anaesthesia in patients with a functioning epidural catheter for labour who require emergency Caesarean section.     

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.     

Quantitative and selective assessment of sensory block during lumbar epidural anaesthesia with 1% or 2% lidocaine

We have examined sensory block during lumbar epidural anaesthesia using a cutaneous current perception threshold (CPT) sensory testing device in 20 patients who received 10 ml of either 1% or 2% lidocaine (lignocaine). CPT at 2000, 250 and 5 Hz stimulation at the trigeminal (V), ninth thoracic (T9) and second lumbar (L2) dermatomes, and dermatomal levels of block to light touch, temperature and pinprick discrimination were measured before and every 5 min until 60 min after epidural lidocaine. There were significant differences between 1% and 2% epidural lidocaine in all CPT at T9 and L2, in addition to maximal cephalad spread of the three sensory modalities. After 2% lidocaine, all CPT increased significantly at T9 and L2. In contrast, only at 250 and 5 Hz for L2 did epidural block with 1% lidocaine produce significant increases in CPT. Maximal level of loss of touch sensation after 1% lidocaine was significantly lower than that of cold and pinprick sensations. We conclude that the dose of lidocaine affected intensity of sensory block during lumbar epidural anaesthesia. In addition, differential neural block resulting from epidural anaesthesia appeared to be associated with a differential effect on nerve fibres of different sizes.      

Subarachnoid anaesthesia for elective Caesarean section

Forty patients who underwent elective lower segment Caesarean section under subarachnoid anaesthesia received either 2.0 ml 0.5% cinchocaine in 6% dextrose or 2.5 ml 0.5% bupivacaine in 8% dextrose via a 26-gauge needle with the patient in the left lateral position. Onset time was rapid in both groups and the distribution of maximum ascent of sensory analgesia was T1-T6. Efficacy of analgesia was greater in the bupivacaine group, although the duration of both sensory and motor blockade was shorter than following cinchocaine. There were no significant differences between the two groups either in the incidence and severity of complications or in the condition of the neonates. The high incidence (50-65%) and often profound extent of hypotension seen throughout the trial, confirm the ineffectiveness of crystalloid preload of 1500 ml as a single prophylaxis against hypotension.     

Extradural ropivacaine and bupivacaine in hip surgery

We studied 126 patients undergoing elective hip surgery; theyreceived 20 ml of 0.5%, 0.75%, 1.0% ropivacaine or 0.5% bupivacaineextradurally in a double-blind design. Sensory block (pinprick),motor block (modified Bromage scale), quality of analgesia andneuromuscular block were assessed intermittently. Heart rateand arterial pressure were measured at regular intervals. Atotal of 115 patients were evaluated for efficacy. Onset ofanalgesia, onset of motor block and maximum cephalad spread(T4) did not differ between the groups. Duration and qualityof analgesia and motor block increased with the concentrationof ropivacaine. Ropivacaine 1.0% provided a longer durationof analgesia and motor block, more intense motor block and morepatients with satisfactory analgesia than 0.5% bupivacaine.More patients treated with the higher concentrations of ropivacainerequired treatment for hypotension and bradycardia.     

Spinal Analgesia with Bupivacaine, Mepivacaine and Tetracaine

Spinal analgesia with bupivacaine, tetracaine and mepivacaine was studied in 103 patients in two studies, one open and one double-blind. Injections were given with the patients sitting and they remained seated for 2 min after the injection. Regardless of the agent used, the mean cephalad spread of analgesia was T6-8 15 min after injection. Mepivacaine 4% (60 mg) in glucose produced analgesia and motor blockade of good quality but of short duration. Bupivacaine 0.5% and 0.75% and tetracaine 1%, all solutions with glucose, produced long-lasting blockades, tetracaine 14 mg having a longer duration of action than 15 mg bupivacaine. When 15 mg of bupivacaine was administered in solutions containing glucose, no difference in sensory blockade was seen, regardless of volume (2 or 3 ml, 0.75% and 0.5%, respectively) injected. 3 ml of bupivacaine 0.75% (22.5 mg) in glucose-free solution produced a very long-lasting blockade with deep motor engagement, particularly suitable for hip surgery of long duration. Bupivacaine 0.75% (3 ml, 22.5 mg) in solution with glucose produced a more marked effect on the blood pressure than the other solutions tested.     

Spinal anaesthesia for Caesarean section: effect of Sprotte needle orientation

We induced spinal anaesthesia in 100 women presenting for elective Caesarean section with the mother in the right lateral position. Patients were allocated randomly to have the side eye of the 24-gauge Sprotte spinal needle pointing in one of four directions: group A, cephalad; group B, right lateral; group C, left lateral; group D, caudad. Isobaric bupivacaine 0.5% (2.5 ml) was injected over 30 s before the mother was placed supine with a 15 degree left lateral tilt. Onset time and height of the subsequent analgesic and anaesthetic blocks were assessed by a blinded observer. Onset of sensory block to T4 was significantly faster in group A (P = 0.001). There were no differences in final block height, incidence of hypotension, nausea and vomiting or ephedrine requirements.      

Dose response study of lidocaine 1% for spinal anaesthesia for lower limb and perineal surgery

Purpose

To compare the sensory and motor block produced by three different volumes of intrathecal lidocaine 1% and thereby determine the appropriate volume to administer for surgery of the lower limbs and perineum.

Methods

Forty-eight patients scheduled for perineal or lower limb surgery were randomly assigned to receive 4, 6 or 8 ml lidocaine 1% intrathecally. The onset, spread, duration and regression of analgesia and motor block and side effects were evaluated (by a blinded observer whenever possible).

Results

The maximum cephalad spread in the 6 ml (T₈ ± 3) and 8 ml (T₄ ± 1.7) groups were higher than the 4 ml group (T₁₂ ± 2.2,P < 0.01). In the 4 ml group, six patients (33%) did not achieve analgesia to T₁₂ and four (22%) did not have complete motor blockade. Patients given 8 ml had longer duration of block (duration at T₁₂: 104 ± 23vs 60 ± 24, 67 ± 14 min,P < 0.01; 8 mlvs 4, 6 ml) and slower recovery times (sensory recovery: 188 ± 27vs 142 ± 27, 157 ± 28 min,P < 0.01; 8 mlvs 4, 6 ml). Two patients (18%) from the 8 ml group and one (5%) from the 6 ml group had transient hypotension.

Conclusion

Four millilitres intrathecal lidocaine 1% is adequate for perineal surgery but for lower limb procedures, 6 ml is more appropriate as it consistently provides sensory analgesia above L₁ dermatome and complete motor block. Eight ml gives an unnecessarily high block with higher incidence of hypotension.     

Sensory and motor blockade during epidural analgesia with 1%, 0.75%, and 0.5% ropivacaine--a double-blind study

Levels of sensory (pinprick) and somatic motor blockade were measured in a double-blind study of 30 volunteers given single epidural injections of 1%, 0.75%, and 0.5% ropivacaine. Onset of analgesia was rapid with all concentrations (7-10 min). Maximal levels of analgesia were established 60 min after injection, with no significant differences in the maximal median cephalad spread. Duration of analgesia at the T-12 level and total duration were significantly longer with 1% and 0.75% than with 0.5% ropivacaine. Motor blockade was assessed by a quantitative method (measurements of isometric muscle force) and a qualitative method (modified Bromage scale). Onset of motor blockade measured by the quantitative method was significantly slower with 0.5% ropivacaine than with the higher concentrations. Maximal muscle weakness occurred 1-1.5 h after injection with all three concentrations. With increase in ropivacaine dose from 100 to 200 mg, the intensity and duration of motor blockade increased. Muscles involved in knee extension were blocked most, those of plantar flexion least. Recovery of motor function, assessed by the above-mentioned quantitative method, occurred simultaneously with the recovery of pinprick perception. Motor blockade registered by Bromage scale showed a slower onset for 0.5% ropivacaine than for the higher concentrations. Mean durations of grade 1 and 2 block were longest for the 1% solution. Motor blockade described by the Bromage scale showed only the first part of the regression phase. Full recovery of muscle strength (Bromage scale = 0) was attained 1.5-2.5 h earlier than assessed by the quantitative method. No adverse effects were registered.     

Lumbar Epidural Anaesthesia With Bupivacaine in Old Patients: Effect of Speed and Direction of Injection

The spread of lumbar epidural analgesia was studied in 48 old urological patients (56–81 years). Bupivacaine 0.5% 20 ml was injected at either 1 ml/s with a Tuohy needle with the bevel directed cephalad (Group I) or caudad (II) and at 0.22 ml/s directed cephalad (III) or caudad (IV). Immediately after injection, the patients moved from a sitting to a horizontal position and analgesia was tested every 2 min by skin pin-prick. At 10 min, there were differences in the mean caudad spread; the greatest spread in Group II was 4.5 segments and the smallest in Group III 2.4 segments, not significant (n.s.). The differences became smaller with time and the maximal spread after 30 min was similar in all groups. In six patients, who all belonged to either Group I or Group III (bevel cephalad), skin analgesia did not reach the S 5 segment. One of the Group I patients developed a transient motor paralysis of the lower extremities immediately upon injection. All patients recovered completely from the block and no toxic reactions were observed. The duration of the block and the accompanying fall of blood pressure were similar in the different groups. The mean venous blood levels of bupivacaine were highest in Group III and lowest in Group I (n.s.). The highest individual bupivacaine blood level was 1.25 μg/ml 30 min after injection, while generally the highest concentrations appeared at 20 min after injection. The study indicated a lack of significant difference on varying the speed of injection or turning the Tuohy needle, but it has to be emphasized that this may apply only to bupivacaine, which has distinct physicochemical properties, and also to old patients with an age-dependently modified epidural space.