Duration of spinal anesthesia with bupivacaine in chronic opium abusers undergoing lower extremity orthopedic surgery.

BACKGROUND: It has been demonstrated that chronic opium abusers have lower thresholds for pain. Spinal anesthesia is a common procedure in anesthesia, which is performed through administration of drugs (usually local anesthetics) in the intrathecal space, to produce temporary pain relief. The aim of this study was to determine whether chronic opium abuse could have any possible effect on the duration of spinal block by bupivacaine. METHODS: In a case-control study, 50 opium abusers and 50 nonabusers undergoing lower extremity orthopedic operations were selected from the patients admitted in Taleghani Hospital in Tehran for elective surgery. The study parameters were assimilated as much as possible, including the method of anesthesia. RESULTS: No statistically significant difference was noted between the two groups regarding the age, sex, and duration of surgery; while, the duration of sensory block was much shorter in the opium abusers (86.6+/-15.7 minutes) compared with the nonabusers (162+/-22.1 minutes) (P<0.0001). CONCLUSION: The study suggests a shortened duration of spinal block with bupivacaine in opium abusers. The results can propose a number of possible mechanisms including cross-tolerance mechanisms between local anesthetics and opioid compounds at the level of spinal neurons. Further molecular studies at the level of spine are suggested.

When do patients given intrathecal morphine need postoperative systemic opiates?

A prospective, randomised study has compared the requirements for intramuscular papaveretum after cholecystectomy in patients given either 0.8 mg intrathecal morphine preoperatively or intravenous papaveretum peroperatively. Patients given intrathecal morphine required significantly less papaveretum during the first 48 hours after operation, but no significant difference in analgesic requirements was observed by 72 hours due to a continuing demand for papaveretum by these patients.

Intrathecal morphine in aortic aneurysm surgery.

The purpose of this study was to compare the peri-operative conditions produced by intrathecal morphine with those that result from conventional analgesia in aortic aneurysm surgery. Low-dose intrathecal morphine provides a level of analgesia during operation indistinguishable from that of moderate doses of parenteral opiate, but is no more effective in attenuating autonomic responses to the procedure. Analgesia is prolonged into the postoperative period, does not cause clinically evident respiratory depression and can be enhanced by small doses of intravenous opiate. The principal advantage of intrathecal morphine is the avoidance of irregular and inadequate pain relief in the early, and most painful, part of the postoperative period. Low-dose intrathecal morphine appears safe, effective and feasible in aortic aneurysm surgery and provides an alternative to traditional management with parenteral opiates.

Intraspinal analgesia: an historical overview.

The application of opioids in the proximity of the spinal cord is a recent addition to the forms of treatment available for pain relief. During the last 20 years we have learned more about the intimate mechanisms of the action of opiates then we had in the preceding 5 millennia. Opium, in fact, has been used for medical purposes from prehistoric times. On the basis of the newly acquired knowledge, we are now applying opioids in more effective ways and providing more patients with long overdue relief of their pain.

Intrathecal baclofen and homeopathy for the treatment of painful muscle spasms associated with malignant spinal cord compression.

In this case study we describe a dual approach to the palliation of difficult muscle spasms using intrathecal baclofen via a fully implanted system, together with the homeopathic approach to symptom control. The homeopathy is seen to complement rather than to replace conventional prescribing and using both approaches together appears to have avoided the necessity for increasing drug doses and to have minimized side-effects. As well as encouraging us to take on experience from other disciplines, this case study also suggests that palliative care could be a forum for evaluating the effectiveness of the homeopathic approach in symptom control in carefully designed studies.

Gastric emptying: a study to compare the effects of intrathecal morphine and i.m. papaveretum analgesia.

Gastric emptying was studied in two groups of 10 patients who underwent elective cholecystectomy. The groups were comparable for age, weight and duration of operation. Gastric emptying was measured with a radioisotopic technique using Tc99m-DTPA (diethylene triamine pentaacetic acid) before, and 24 h after, surgery. Analgesia was provided by intrathecal morphine 0.8 mg alone (group A) or by i.m. papaveretum 10 mg, administered as required, plus one additional dose 1 h before the postoperative measurement (group B). Control gastric emptying rates were not significantly different in the two groups (mean +/- SD: A = 76.6 +/- 23.0 ml; B = 81.8 +/- 16.3 ml in 30 min). After surgery, gastric emptying was significantly greater in group A (42.9 +/- 35.6 ml) than in group B (11.0 +/- 27.9 ml) (P less than 0.05).

Central nervous system effects of intrathecal muscle relaxants in rats.

When given for a sufficient time and dose intravenously, neuromuscular blocking drugs eventually can enter the cerebrospinal fluid (CSF). To study the potential pharmacologic consequences of neuromuscular blocking drugs in the CSF, a model was developed in the rat by using an intrathecal infusion of these drugs. A cannula was stereotaxically implanted in a lateral cerebral ventricle of anesthetized male Sprague-Dawley rats (250-300 g). Several days later, the effects of an intraventricular infusion (5 microL/min) of atracurium (0.804 mumol/mL), pancuronium (0.172 mumol/mL), and vecuronium (21.978 mumol/mL) were studied in unanesthetized rats. These rats (n = 6 in each group) exhibited dose-dependent hyperexcitability, during drug infusion, with seizures occurring at threshold doses of (mean), 0.12, 0.26, and 0.065 +/- 0.010 and 3.32 mumol/kg of atracurium, pancuronium, and vecuronium, respectively. The neuromuscular ED50 (intravenous dose required to produce a 50% depression of twitch tension) in rats determined by other investigators are 0.408, 0.115, and 0.352 mumol/kg for atracurium, pancuronium, and vecuronium, respectively. Therefore, seizure threshold doses were not related to the potencies of these drugs as neuromuscular blocking drugs. Based on these data, central nervous system effects were studied over the subseizure dose range approximating 1/100, 1/10, and 1/5 of the cumulative dose causing seizures for each drug (n = 5 for each dose). At 1/100 of seizure dose, decreased locomotor activity and piloerection occurred. At 1/10 to 1/5 of seizure dose, agitation, shivering, splayed limbs, and whole body shaking resulted.(ABSTRACT TRUNCATED AT 250 WORDS)