Sufentanil citrate and morphine/bupivacaine as alternative agents in chronic epidural infusions for intractable non-cancer pain.

Intraspinal narcotic (usually intrathecal morphine) infusions with implanted pumps are increasingly used in patients with intractable chronic pain not caused by cancer. In some patients, pain control is difficult with infusions of morphine. Seven patients with diagnoses of arachnoiditis, epidural scarring, and/or vertebral body compression fracture were treated with alternative solutions in an epidural route. For maximal flexibility, Medtronic implanted programmable infusion pumps with catheters to T6-T10 were used, and pain was monitored by verbal pain scales. In three patients, epidural infusions of morphine in 0.5% bupivacaine (MS-MARC) resulted in little or no pain relief without significant side effects (e.g., headache, nausea, or vomiting). In these same patients, epidural infusions of sufentanil citrate resulted in pain scale reductions of 92%, 82%, and 40%, respectively, with no side effects. Four other patients found more effective pain relief when switched from initial sufentanil citrate infusions to MS-MARC. Pain scale reductions (with no side effects) were 92%, 76%, 59%, and 47% in these patients. Pain relief and minimal side effects with sufentanil citrate is theorized to result from its higher lipophilicity promoting local transdural diffusion to spinal cord and limiting upward diffusion to the brain stem. Sufentanil citrate is also advantageous for programmable pumps because it is 100 times more potent than morphine and therefore allows longer pump refill times and higher infusion doses. Although this study was done on a limited number of patients, sufentanil citrate and MS-MARC in epidural infusions using programmable infusion pumps for non-cancer patients provide significant alternative drug combinations and routes.

Effects of different glucose concentrations on spinal anaesthesia with bupivacaine and tetracaine.

The effects of 5% and 8% glucose in 0.5% tetracaine or bupivacaine on the anaesthetic spread were investigated in 80 urological patients requiring spinal anaesthesia for trans-urethral resection of the prostate. The local anaesthetic solutions were randomly administered, the patients being divided into four groups of 20, and the anaesthetic profile was then evaluated in a double-blind fashion by an independent observer. Maximum cephalad spread of analgesia was significantly greater with tetracaine in 8% glucose compared to the other three groups (tetracaine/5% glucose, bupivacaine/5 or 8% glucose) (P less than 0.05). Glucose concentration significantly influenced spreading characteristics of tetracaine, the 8% solution achieving a higher level in a shorter time than the 5% solution. Sensory regression to both T10 and S1 dermatome was longer with bupivacaine in 8% glucose compared to 5% glucose. The concentration of glucose, however, did not influence the regression of sensory analgesia for tetracaine. Both the 5% and 8% solutions of tetracaine achieved a 3+ motor blockade significantly faster than either bupivacaine solution. Regression of motor blockade from tetracaine was not influenced by the glucose concentration, but the 8% solution of bupivacaine had a delayed 2+ and 3+ blockade, although the ultimate decay for both solutions was similar. The results of our study suggest that 0.5% bupivacaine 4 ml in 5% glucose provides a rapid and controllable spread of sensory analgesia for transurethral surgery, of optimal duration associated with a complete motor blockade of moderate duration.

Influence of barbotage on block characteristics during spinal anesthesia with hyperbaric tetracaine and bupivacaine.

Barbotage is the aspiration of the injected volume back into the syringe followed by reinjection twice, with 0.5 ml increases in each aspirated volume. The effects of this technique versus injection without barbotage, on the spinal anesthetic spread of 0.5% tetracaine or 0.5% bupivacaine in 5% glucose 4 ml each, were investigated in 80 men undergoing urologic surgery. The local anesthetic solutions were randomly injected into four groups of 20 patients each, and the anesthetic profile of each solution was then evaluated in a double-blind fashion for the two techniques (barbotage/without barbotage) by an independent observer. In the tetracaine groups, barbotage was associated with a higher dermatome level and shorter time to reach this compared with tetracaine without barbotage. Barbotage caused the latency of bupivacaine to be shorter, but the actual time difference was small and clinically not relevant. Comparing tetracaine and bupivacaine, tetracaine with barbotage achieved a higher segmental level. Time to highest dermatome, however, was shorter for bupivacaine with barbotage compared with tetracaine with barbotage. Barbotage shortened the onset of 3+ motor block with bupivacaine. This difference was statistically significant. Results suggest that barbotage is useful to shorten the time for full development of analgesia when using 0.5% hyperbaric tetracaine. Barbotage with 0.5% hyperbaric bupivacaine, however, has the advantage of intensifying and shortening the onset time of a complete motor block.

Cardiovascular and subjective central nervous system effects of long-acting local anaesthetics in man.

Intravenous infusions of etiodocaine 50, 75 and 100 mg and bupivacaine 75 mg were carried out over ten minutes in healthy young adult males. Cardiovascular sequelae were generally trivial at all doses. A collection of subjective central nervous system symptoms were described which may be regarded as early warning of impending local anaesthetic toxicity. Plasma concentrations of etidocaine were proportional to dose and ranged from 2 micrograms/ml to 5 micrograms/ml at the termination of the infusion. Plasma concentrations of bupivacaine were similar to those from the same dose of etidocaine but declined more slowly on cessation of infusion.