Robert I. Balfour

Bupivacaine: a review of 11,080 cases.

Bupivacaine (Marcaine®) hydrochloride, a long-acting local anesthetic drug, was used in concentrations of 0.25, 0.5, or 0.75 percent with and without a vasoconstrictor, in amounts ranging from 25 to over 600 mg, for caudal, epidural (peridural), or peripheral nerve block for 11,080 surgical, obstetrical, diagnostic, or therapeutic procedures. Onset of anesthesia occurred in 4 to 10 minutes and maximum anesthesia in 15 to 35 minutes. Concentrations of 0.25, 0.5, and 0.75 percent consistently produced complete sensory anesthesia of the integumentary and musculoskeletal systems. With 0.25 and 0.5 percent, motor blockade ranged from minimal to complete. In intra-abdominal surgery, only 0.75 percent consistently produced profound muscle relaxation. Fifteen systemic toxic reactions occurred, but no untoward sequelae resulted from them. One inadvertent subarach- noid injection of 110 mg resulted in a total spinal block with an uneventful recovery.

Arterial and Venous Plasma Levels of Bupivacaine Following Epidural and Intercostal Nerve Blocks

Arterial and peripheral venous plasma levels of huptvacaine were determined in 30 patients following epidural anesthesia using 150 and 225 mg, as well as following intercostal nerve block with 400 mg. Arterial levels were consistently higher than levels in simultaneously sampled venous blood, and the highest levels occurred with bilateral intercostal nerve block. No evidence of systemic toxicity was observed. The results suggest that bupivacaine may have a wider margin of safety in man than is now stated.

Arterial and venous plasma levels of bupivacaine following peripheral nerve blocks.

Mean arterial plasma (MAP) and peripheral mean venous plasma (MVP) levels of bupivacaine were ascertained in 3 groups of 10 patients each for: (1) intercostal nerve block, 400 mg; (2) block of the sciatic, femoral, and lateral femoral cutaneous nerves, with or without block of the obturator nerve, 400 mg; and (3) supraclavicular brachial plexus block, 300 mg. MAP levels were consistently higher than simultaneously sampled MVP levels, the highest levels occurring from bilateral intercostal nerve block. No evidence of systemic toxicity was observed. The results suggest that bupivacaine has a much wider margin of safety in humans than is now stated.

Factors determining dosages of amide-type local anesthetic drugs.

The physical status of the patient (sex, age, weight, height, and underlying disease) has been thought to influence the dosage of local anesthetic drugs that can be injected without causing a systemic toxic reaction, but this belief is not supported by statistically significant data. Furthermore, previous studies of plasma levels of bupivacaine and mepivacaine showed no correlation between dosage and physical status, even when maximum dosages recommended by pharmaceutical companies were exceeded. This study of 9,287 regional blocks, using the statistical tests of multiple regression and chi square, substantiates that the occurrence of systemic toxic reactions in adults does not correlate with dosages and/or physical status of the patient when 400 mg or less of bupivacaine, 450 mg or less of etidocaine, or 500 mg or less of mepivacaine is used. Therefore, the study questions the maximum dosages established for certain local anesthetic drugs, as well as the method by which such dosages were established.

Role of Epinephrine in Regional Block Anesthesia With Etidocaine: A Double-blind Study

Fifty healthy females scheduled for abdominal hysterectomy were administered 1 percent etidocaine (20 ml.) for lumbar epidural block anesthesia. Use of a plain solution or a solution containing 1:200,000 epinephrine was pre-selected randomly and administered in a double-blind fashion. Measurements of onset and duration of sensory anesthesia did not vary significantly between the two groups. Motor anesthesia did have a faster onset in patients receiving solutions containing epinephrine but the duration or quality of motor anesthesia did not vary significantly.An additional five patients were given bilateral intercostal nerve block anesthesia with plain solutions of 0.5 percent etidocaine (60 ml.) for clinical comparison with previously studied patients who received similar blocks with solutions containing epinephrine. No apparent clinically significant difference was noted.Plasma levels of etidocaine were measured for both techniques. Although the plain solutions produced higher blood levels than the epinephrine containing solutions for both techniques, they were not significantly different. The conclusion of this study is that the addition of 1:200,000 epinephrine to solutions of etidocaine for lumbar epidural and intercostal nerve block may provide some protection against systemic toxicity but has little if any benefit on the clinical effects of the drug.

Intra-aortic balloon counterpulsation for the treatment and prevention of cardiogenic shock

Abstract Of the thirteen patients who have had intra-aortic balloon counterpulsation for cardiogenic shock, six are long-term survivors. Four additional patients have had anticipatory counterpulsation, and three are long-term survivors.

Bupivacaine compared with etidocaine for vaginal delivery.

A comparison of 0.5 percent etidocaine with 0.25 and 0.5 percent bupivacaine, using continuous (intermittent) caudal block in 60 vaginal deliveries, showed the latter two solutions to be the agents of choice. All solutions contained a final concentration of 1:200,000 epinephrine. In 40 parturients given either 0.25 or 0.5 percent bupivacaine, all had pain relief after the initial dose, while 5 of 20 given etidocaine required a refill dose within 30 to 50 minutes for complete pain relief. The duration of action of the initial dose with both concentrations of bupivacaine was longer than that of etidocaine. The degree of motor blockade with 0.5 percent etidocaine was greater than with 0.5 percent bupivacaine, and with 0.5 percent concentrations of either etidocaine or bupivacaine was greater than with 0.25 percent bupivacaine. The duration of motor blockade of 0.5 percent etidocaine and bupivacaine was comparable. The duration of motor blockade of the 0.25 percent concentration of bupivacaine was shorter than with the 0.5 percent concentration of both etidocaine and bupivacaine; and with both bupivacaine concentrations the duration of sensory anesthesia in the extremities was longer than motor blockade; with etidocaine, the opposite occurred.

A double-blind study of bupivacaine and etidocaine for epidural (peridural) block.

In a double-blind comparison of two long-acting local anesthetic agents, 0.75 percent bupivacaine and 1 percent etidocaine, using epidural block for abdominal hysterectomy, no significant differences occurred in: (1) onset of sensory anesthesia, (2) time for establishment of maximum sensory anesthesia, (3) maximum dermatome level of sensory anesthesia, (4) relaxation of the abdominal musculature, or (5) degree of motor blockade of the extremities.However, the following significant differences between the two agents were noted: (1) satisfactory anesthesia occurred in 24 of 25 patients with 0.75 percent bupivacaine and in only 12 of 25 patients with 1 percent etidocaine; (2) motor anesthesia of the extremities occurred more rapidly with etidocaine; (3) duration of motor anesthesia of the extremities, time for regression of sensory anesthesia, and duration of sensory anesthesia were markedly longer with bupivacaine; and (4) the time from injection of local anesthetic solution into the epidural space until the patient requested a narcotic for pain in the operative site was also longer with bupivacaine.