Comparison of 0.75% ropivacaine with epinephrine and 0.75% bupivacaine with epinephrine in lumbar epidural anesthesia.

Forty-three ASA physical status I and II patients, scheduled for elective urologic surgery, were randomly entered into a randomized double-blind study using 20 ml bupivacaine 0.75% or 20 ml ropivacaine 0.75%, both with 5 micrograms/ml epinephrine. Two patients were excluded from evaluation of efficacy due to technical failure. After a test dose of 3 ml bupivacaine 0.75% with epinephrine or ropivacaine 0.75% with epinephrine, 17 ml of either solution was given in incremental doses over 4 minutes (4, 4, 4, and 5 ml). Analgesia was satisfactory for surgery in all patients except for one in each group. The onset time of analgesia was short: after administration of ropivacaine and bupivacaine, the T12 dermatome was blocked within 6-8 minutes. Mean maximum upper level of analgesia was similar in the groups--T8 +/- 0.6 and T7 +/- 0.6 (mean +/- SEM)--for ropivacaine and bupivacaine, respectively. Duration of analgesia at the T10 level was 190 +/- 12 minutes in the ropivacaine group and 234 +/- 20 minutes in the bupivacaine group and was significantly shorter for ropivacaine at T10, L2, and S5 segments. Frequency of complete motor block was significantly lower in the ropivacaine group (7/21) than in the bupivacaine group (16/20). No differences were found in onset to various degrees of motor block, however, the duration of degree 1 motor block was significantly shorter in the ropivacaine group. Hypotension and bradycardia requiring treatment were experienced by seven and three patients, respectively, in the bupivacaine group, and by two and one patient, respectively, in the ropivacaine group. No postoperative adverse events related to anesthesia were observed. Ropivacaine 0.75% with epinephrine is an effective long-acting local anesthetic. Duration of sensory block is similar to that of bupivacaine 0.75% with epinephrine; however, the motor block is less profound and of shorter duration.

Local anesthetic efficacy of ropivacaine (LEA 103) in ulnar nerve block.

Ropivacaine (LEA 103) is a new long-acting local anesthetic that in animal experiments has proved to be equally potent but less toxic than bupivacaine. In this controlled double-blind study in man, the dose-response relation of ropivacaine was examined in peripheral nerve block and its potency was compared to that of bupivacaine. Nerve functions during bilateral ulnar nerve block were monitored in 70 normal subjects by a computer-controlled method. Results indicate that plain ropivacaine is optimally effective at concentrations between 0.5% and 0.75%, where it reliably blocks nerve functions for about 8 hours. Its profile of action is uniform for the different fiber groups and resembles that of bupivacaine. Addition of epinephrine does not improve latency or duration of ropivacaine nerve block. Adverse effects attributable to ropivacaine have not been observed.

An open study comparison of 0.5%, 0.75% and 1.0% ropivacaine, with epinephrine, in epidural anesthesia in patients undergoing urologic surgery.

Ropivacaine 0.5%, 0.75% and 1.0% with epinephrine 5 micrograms/ml was investigated in an open, multi-center study for lumbar epidural anesthesia in 46 patients undergoing urologic surgery. The onset time for analgesia to T12 was 5-7 minutes after the end of the ropivacaine injection. Maximum segmental levels of analgesia (T4-6) were not different between the groups. Complete motor blockade was obtained in 3/15, 7/15 and 10/15 patients in the 0.5%, 0.75% and 1.0% groups, respectively. Duration of analgesia at the T10 level was 2.5 hours in the 0.5% group, and increased to 4 hours in the 1.0% group. Analgesia was satisfactory for surgery in all patients except for 2/15 in each of the 0.5% and 0.75% groups and 1/15 in the 1.0% group. Hypotension was experienced by three, six and three patients in the 0.5%, 0.75% and 1.0% groups, respectively. Bradycardia was seen in two patients in the 0.5% group and one patient in the 1.0% group. Backache was experienced by seven patients (four in the 0.5%, two in the 0.75% and one in the 1.0% group). No late-occurring adverse experiences were observed. In conclusion, 0.5%, 0.75% and 1.0% ropivacaine with epinephrine provide adequate analgesia and motor blockade for urologic surgery.

Visceral pain during caesarean section under spinal and epidural anaesthesia with bupivacaine.

In a randomized study, the incidence of visceral pain was evaluated in 46 patients undergoing elective caesarean section under spinal or epidural anaesthesia with 0.5% bupivacaine. If the patient experienced pain during the operation, a standard visual analogue scale ranging from 0 to 10 was used to assess the degree of pain. Visceral pain occurred in 12/23 patients in the spinal group and in 13/23 patients in the epidural group. In neither group was a correlation found between the cephalad level of analgesia or the intensity of cutaneous analgesia in the sacral region, and the presence of visceral pain.

Effect of fluid preloading on cardiovascular variables after spinal anaesthesia with glucose-free 0.75% bupivacaine.

We studied the effect on systemic arterial pressure of fluid preloading with 1 litre of crystalloid fluid before spinal anaesthesia in 40 patients undergoing minor lower abdominal or lower limb surgery. Fluid was given at a rate of either 1 ml min-1 (no preload group), or 1000 ml in the 15 min (preload group) immediately before induction of spinal anaesthesia with 3 ml of 0.75% glucose-free bupivacaine. There was no difference between the groups in the character of anaesthesia or motor block in the lower limbs. The cephalad spread of analgesia ranged from L1 to C8. Analgesia was insufficient for surgery without supplementary analgesia in three patients in each group. The group not given a fluid preload had significantly lower arterial pressures (P less than 0.05) when anaesthesia extended above the T5 dermatome. The mean time before the lowest arterial pressure was recorded was twice as long in the preloaded group as in the non-preloaded group. Glucose-free 0.75% bupivacaine did not give a reliable extent of anaesthesia for lower abdominal surgery.

The effect of rate of infusion on continuous epidural analgesia for labor and delivery.

The authors previously reported that if a loading dose of 50 mg bupivacaine was followed by infusion of 0.0625% bupivacaine (12.5 mg/hr), supplemental doses to achieve satisfactory analgesia for labor and delivery were required in 50% of patients. The current study was done to determine whether increasing the dose from 12.5 to 25 mg/h would eliminate the need for supplemental injections. Twenty-three healthy parturients were randomly assigned to one of two groups--Group I: 0.125% bupivacaine at 20 ml/hr (25 mg/hr); or Group II: 0.25% bupivacaine at 10 ml/hr (25 mg/hr). Taking both groups together, the 50-mg bupivacaine loading dose followed by 25 mg/hr provided adequate analgesia for labor and delivery in 74% of the patients. Two parturients in Group I and three in Group II required supplemental boluses of 4 ml of 0.5% bupivacaine for delivery. Pharmacokinetic data were similar in both groups. Using a dose of 25 mg/hr resulted in 74% of the patients obtaining adequate analgesia for labor and delivery. This improvement over the 50% success rate in the previous study, was achieved without any evidence of toxicity.

Respiratory diseases in iron ore miners and millers.

Workers in iron mines are at risk of developing interstitial lung disease if the dust levels are above the threshold limit value. However, they more commonly develop the usual diseases that affect all workers. Some illnesses, such as chronic bronchitis, bronchial asthma, and the collagen vascular diseases that affect the lung, may be more severe because of the inhalation of dust. The most difficult problem is to differentiate asymptomatic sarcoidosis from pneumoconiosis. The family doctor who also acts as the company doctor must be aware of the potential conflict of interest.

Pneumoconiosis in iron ore surface mining in Labrador.

A cross-sectional survey of the work force at an iron ore surface mine and beneficiation plant in Labrador identified cases with a radiologic diagnosis compatible with simple pneumoconiosis by the International Labour Organization (ILO) classification (1980). Their distribution by ILO categories 1, 2, and 3, after excluding those with confounding diagnoses for pneumoconiosis, was 30, 10, and 2 cases, respectively. ILO category was related to age, duration of current employment, and cumulative respirable dust and quartz levels, as well as to decrement in ventilatory function.

Effects of posture and baricity on spinal anaesthesia with 0.5% bupivacaine 5 ml. A double-blind study.

In four groups of 10 patients, 0.5% bupivacaine 5 ml was used in spinal anaesthesia for gynaecological surgery. Group 1 received plain solution in the sitting position, group 2 plain solution in the lateral position, group 3 hyperbaric solution in the sitting position and group 4 hyperbaric solution in the lateral position. All patients were returned to the horizontal supine position, the sitting subjects 2 min after, and the lateral subjects immediately after, spinal injection. In each group the mean height of block was to the mid-thoracic segments, but there was no significant difference between the groups. There was, however, considerable scatter within each group. Posture had some effect on the speed of onset of the analgesia, but no significant effect on the final outcome. The use of 0.5% bupivacaine as a test dose in extradural blockade is discussed.

Spinal anaesthesia with hyperbaric bupivacaine: effects of concentration and volume when administered in the sitting position.

In a double blind study, solutions of 0.5% or 0.75% bupivacaine containing 8% dextrose were compared with regard to the effect of varying concentration and volume when administered intrathecally to patients in the sitting position. Ten patients received 3 or 4 ml of 0.5% bupivacaine or 2 or 3 ml of 0.75% bupivacaine. Nine patients received 0.5% bupivacaine 2 ml and another nine received 0.75% bupivacaine 1.3 ml. The use of the 10-mg dose of both solutions was abandoned after nine patients in each group because of insufficient cephalad spread. With both solutions, the smallest volumes (bupivacaine 10 mg) had significantly shorter durations of action than both the larger ones (15-20/22.5 mg), between which there were no significant differences.

Absorption of bupivacaine after topical application to the oropharynx.

Bupivacaine in dosages of 20, 40, 60, or 80 mg was applied by spray to the oropharynx of 24 volunteers. Blood levels of bupivacaine were detectable at 10 minutes, peaked at 60-90 minutes, and were still measurable at 150 minutes after administration. The maximum bupivacaine plasma level recorded in any volunteer was 0.96 -g/mL (after 80 mg). Increase in pulse rate and decrease in systolic blood pressure were significantly correlated with increasing bupivacaine dosage. No clinical signs or symptoms of drug toxicity were observed in any subject.

Hypotension in spinal anesthesia: a comparison of isobaric tetracaine with epinephrine and isobaric bupivacaine without epinephrine.

Two isobaric spinal anesthetic solutions (bupivacaine 0.5%/20 mg without epinephrine and tetracaine 0.5%/15 mg with 0.2 mg epinephrine) were compared in a double-blind study of 60 patients. Patients were injected while in the lateral recumbent position and were immediately turned supine and horizontal. Up to 30 min after injection, no differences were found between the groups regarding segmental level of analgesia, changes in heart rate, and onset to or maximum decrease in mean arterial pressure (MAP). No correlation was found between maximum decrease in MAP and level of analgesia. At time of maximum decrease in MAP (tetracaine group - 16.7 +/- 12.8% (mean + SEM), bupivacaine group -19.4 + 14.8%) the level of analgesia was significantly higher in the tetracaine group (T5-6) than in the bupivacaine group (T7-8). Hypotension occurred in five patients in the bupivacaine group and in six in the tetracaine group. Two patients in the tetracaine group (but none in the bupivacaine group) had bradycardia. Hypotension together with bradycardia was observed in one patient in the tetracaine group but in no patient in the bupivacaine group. Two patients in each group developed postlumbar puncture headache. The authors conclude that the choice of local anesthetic agent, by itself, is not the sole cause of hypotension seen with spinal anesthesia.

Comparison of continuous epidural infusion of a local anesthetic and administration of systemic narcotics in the management of pain after total knee replacement surgery.

Continuous bupivacaine epidural analgesia was compared with conventional methods of systemic analgesic administration in the management of postoperative pain in 30 patients for 3 days following total knee replacement surgery. Patients given continuous epidural analgesia had significantly better pain relief (visual analogue scale, global evaluation), needed significantly fewer supplementary analgesics, and had significantly fewer side effects. In the epidural group, sensory block averaged six dermatomes on day 1 and four dermatomes on day 3. The number of patients with complete (or almost complete) motor block of the lower limbs decreased from eight on day 1 to five on day 3. The mean dosage of bupivacaine decreased from 21.0 +/- 5.7 (SD) mg/hr on day 1 to 15.1 +/- 8.5 mg/hr on day 3. No signs of accumulation of or toxic reactions to bupivacaine were seen.

Addition of glucose to bupivacaine in spinal anesthesia increases incidence of tourniquet pain.

The effect of baricity of 0.5% bupivacaine on the incidence of tourniquet pain when used for spinal anesthesia was evaluated in 60 patients undergoing orthopedic surgery. Three ml of either hyperbaric (8% glucose) or isobaric (glucose-free) solution was used. A standard 7-cm orthopedic tourniquet was applied at the thigh and was inflated to 300 mm Hg for 2 hr or until the patient experienced pain from the tourniquet. During application time, the levels of sensory block to pin prick were similar in the groups. The incidence of tourniquet pain in the glucose-free group (4/30) was significantly lower than in the hyperbaric group (11/30).

Venous blood concentrations after subarachnoid administration of bupivacaine.

Peripheral venous blood concentrations of bupivacaine were measured in 51 patients given 0.5% (4 ml, 20 mg) or 0.75% (3 ml, 22.5 mg) bupivacaine, both solutions with or without glucose, for spinal anesthesia. The initial absorption of bupivacaine, as measured in peripheral venous blood, was rapid, although the blood concentrations were low. The mean peak concentration (Cmax) did not differ when glucose was added to 0.5 or 0.75% bupivacaine. When glucose-free and glucose-containing bupivacaine groups were combined, 22.5 mg bupivacaine give a significantly higher venous blood concentration than 20 mg of the solution. The mean time between subarachnoid injection and the time when Cmax was reached (tpeak) was influenced by the density of bupivacaine, i.e., the tpeak of bupivacaine with glucose was significantly shorter than with glucose-free solution (35 min; P less than 0.05). No correlation was found between Cmax and the age, height, or weight of the patients, or between Cmax and the maximum cephalad level of analgesia in the different groups. In addition, there was no correlation between tpeak and the age, height, or weight of the patients. The maximal cephalad level of analgesia did not influence tpeak in the different groups (the correlation coefficients less than 0.3).

Comparative effects of intrathecal bupivacaine and tetracaine on analgesia, cardiovascular function and plasma catecholamines.

Forty otherwise healthy male patients, scheduled for elective inguinal herniotomy, were randomly allocated to spinal anaesthesia with 3 ml 0.5% hyperbaric tetracaine or bupivacaine under double-blind conditions. The extent of blockade (pin-prick and cold sensation), blood pressure and heart rate and plasma catecholamines were measured before and 5, 10, 15, 20 and 30 min after injection, before skin incision. Cephalad spread of sensory and temperature analgesia was insignificantly higher after tetracaine. The mean time taken to reach maximal spread of analgesia was 22 min in both groups. Mean arterial pressure showed a more pronounced decrease in the tetracaine group (22 vs 12%, P less than 0.009). Heart rate fell slightly and similarly in both groups, while rate-pressure product was significantly lower in the tetracaine group. The correlation between the decrease in mean arterial pressure and the cephalad spread of sensory analgesia was similar in the two groups, suggesting that at identical levels of sensory analgesia changes in blood pressure were similar after tetracaine and bupivacaine. Plasma norepinephrine and epinephrine measurements before spinal puncture and at maximal decrease in mean arterial pressure showed a depressed response to fall in blood pressure in the tetracaine group. It is concluded that spinal anaesthesia with 3 ml hyperbaric 0.5% tetracaine is followed by a more pronounced fall in blood pressure compared to an identical dose of bupivacaine. The more pronounced sympathetic blockade, confirmed by plasma catecholamine measurements, following tetracaine is probably due to a higher cephalad spread of neurogenic blockade, rather than a differential effect on sympathetic nerve fibres.

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.

Subarachnoid anaesthesia with 0.5% bupivacaine: effects of density.

The effects of subarachnoid administration of 0.5% bupivacaine 4 ml in 8%, 5% or 0% glucose were investigated in a double-blind study in 30 women undergoing laparotomy through a lower abdominal incision. The onset time for maximum segmental spread of analgesia was 10-15 min for all solutions. Cephalad segmental spread of analgesia was three to four segments higher with the hyperbaric solutions (T4-5 v. T7-8). Time of onset of complete motor blockade of the lower limbs was 5-10 min for all solutions. The glucose-free solution did not produce sufficient surgical anaesthesia because of too low cephalad spread. Duration of motor blockade generally decreased with increasing glucose concentration, only the hyperbaric solutions providing useful for abdominal surgery, with a duration of 1-1.5 h. Anaesthesia (halothane) was required in seven of 10 patients in the glucose-free group and in five of 20 in the hyperbaric groups. No occurrence of "post-spinal headache" was recorded in the study.

Spinal analgesia with glucose-free bupivacaine--effects of volume and concentration.

Spinal analgesia using 22.5 mg glucose-free bupivacaine, given either as 3.0 ml of 0.75% solution or 4.5 ml of 0.5% solution was studied in a double-blind fashion in 40 patients scheduled for transurethral surgery. No differences in onset, duration and regression of analgesia or motor blockade were noticed, indicating that dosage (in mg) is more important than either volume or concentration when glucose-free bupivacaine solutions are used for spinal analgesia. The cardiovascular effects were small and no side-effects attributable to the spinal anaesthetic were seen.