Effect of premedication with controlled-release oral morphine on postoperative pain

Thirty fit patients presenting for elective total hip replacement were randomly allocated to receive a premedication of 60 or 90 mg controlled-release oral morphine or 15 mg intramuscular morphine. Postoperative analgesia was assessed using on-demand intravenous pethidine supplementation requirements. In 15 patients free plasma morphine concentrations were measured. Both 60 and 90 mg controlled-release oral morphine led to a reduced pethidine requirement compared to the intramuscular group but the reduction was not statistically different.     

Continuous subcutaneous infusion of morphine for postoperative pain relief

A double-blind randomised study of 48 patients in whom continuous subcutaneous infusion and regular intramuscular injection of morphine were compared as analgesic regimens after upper abdominal surgery, is described. Over a 48-hour period, no difference in pain intensity between the two groups was found by comparing linear analogue scores, assessments on a four-point rank scale, peak expiratory flow rates or requirement for additional analgesia. Nausea and sedation were assessed using a four-point rank scale. These side effects were less frequent with subcutaneous infusion (p less than 0.05). Two patients from each group were judged to have received an overdose. The infusion apparatus was simple and convenient to use. Continuous subcutaneous infusion of morphine is a practical and effective means of achieving post-operative analgesia but, as with other mandatory dosing regimens, relative overdosage may occur.     

Thoracic epidural infusion for postoperative pain relief following abdominal aortic surgery: bupivacaine, fentanyl or a mixture of both?

Thirty patients who had undergone elective abdominal aortic surgery were studied in a prospective, randomised double-blind comparison of thoracic epidural 0.2% bupivacaine alone, thoracic epidural fentanyl alone and thoracic epidural 0.2% bupivacaine combined with fentanyl. Pain relief, pulmonary function, cardiovascular stability and side effects were assessed. Pain relief was excellent in the combined bupivacaine-fentanyl series, being significantly better than the other groups (p less than 0.05) during the entire study period and was not accompanied by hypotension. Forced expiratory parameters were reduced in all groups throughout the study to 50-60% of the pre-operative values, but there were no significant differences between groups. The incidence of side effects attributable to either epidural bupivacaine or fentanyl was low. This study supports the increasing use of epidural infusion analgesia for postoperative pain management after abdominal surgery.     

Thoracic epidural infusions for post-thoracotomy pain: a comparison of fentanyl–bupivacaine mixtures vs. fentanyl alone

A randomised double-blind clinical trial was conducted on 106 patients scheduled for pulmonary resection. Patients received an epidural infusion containing 0.1%, 0.2% bupivacaine or saline in combination with fentanyl 10 microgram.ml -1. Adequacy of analgesia was assessed at rest and during movement over 24 h. Analgesic efficacy was assessed using visual analogue scores and an observer/verbal ranking scale. Pain scores were higher in the fentanyl-only group at the 2 h assessment (p < 0.05). Otherwise, there were no between-group differences in pain scores or in the total amounts of epidural solution used. All patients received continuous haemodynamic monitoring. There were no between-group differences in the number of episodes of hypotension or in the number of interventions for hypotension. However, the use of intra-operative vasopressor and the incidence of temporary neurological complications was higher in the 0.2% bupivacaine group (p < 0.05). We conclude that, in the early postoperative period, the addition of bupivacaine 0.1% improves fentanyl epidural analgesia in patients undergoing lung resection and is not associated with the disadvantages seen with the addition of bupivacaine 0.2%.     

Epidural buprenorphine for pain relief after major abdominal surgery. A controlled comparison with epidural morphine

In a controlled trial epidural buprenorphine was compared with epidural morphine as the sole means of analgesia after major abdominal surgery. Bolus injections of buprenorphine 60 micrograms in 10 ml or morphine 2 mg in 10 ml of normal saline were given on demand for the first 48 hours postoperatively. Both drugs produced significant reduction in pain scores as assessed by the linear visual analogue scale and both produced prolonged analgesia at this dosage, which could be extended by further 'top-ups'. The authors conclude that, for postoperative epidural analgesia, buprenorphine may be the opiate of choice and the reasons for this are discussed.     

Continuous thoracic epidural fentanyl for post-thoracotomy pain relief: with or without bupivacaine?

Twenty-five ASA 1 or 2 patients undergoing thoracotomy were entered into a prospective, randomised, double-blind study comparing thoracic epidural fentanyl alone and thoracic epidural fentanyl combined with 0.2% bupivacaine. Pain relief, pulmonary function and cardiovascular stability were assessed. Pain relief was superior in the bupivacaine series (p less than 0.05) during the first day after operation and this was accompanied by better oxygenation (p less than 0.05); the difference did not persist into the second day. Forced expiratory variables were reduced in both series to 50-60% of the values before operation throughout the study (p less than 0.05) and differences did not occur between the groups. The incidence of side effects attributable to epidural fentanyl was high, but hypotension did not occur. Small doses of bupivacaine administered together with fentanyl into the thoracic epidural space improve analgesia without causing hypotension.     

Perineuronal morphine: a comparison with epidural morphine

In a double-blind, randomised controlled cross-over study the effects of perineuronal (perifemoral) injections of morphine were compared with epidural injections with the same amount of morphine in patients after knee surgery. Better pain scores were achieved during treatment with epidural morphine. We have not been able to confirm the hypothesis of neuro-axonal transport of morphine from the periphery to the spinal cord.     

A comparison of opioid solutions for patient-controlled epidural analgesia

Sixty patients took part in a randomised, double-blind study to compare the analgesic and side effects of three opioid-containing solutions for patient-controlled epidural analgesia following abdominal surgery. Patients in group 1 received a solution containing bupivacaine 0.125% with fentanyl 10μg. ml⁻¹, group 2 bupivacaine 0.125% with diamorphine 125μg. ml⁻¹, group 3 pethidine 2.5 mg. ml⁻¹. All groups received 4 ml.h⁻¹ background infusion and 3 ml boluses every 20 min if necessary. There were no significant differences between the groups in visual analogue scale pain scores (p = 0.537) or volumes of solution used at 24 h (p = 0.351) or 48 h (p = 0.105). Motor block was significantly higher in group 2 (p < 0.004) and pruritis occurred significantly less in group 3 (p < 0.05). We conclude that these three solutions produce equivalent analgesia but that pethidine 2.5 mg. ml⁻¹ may be associated with fewer side effects.     

A double-blind comparison of codeine and morphine for postoperative analgesia following intracranial surgery

Codeine and morphine were compared in a double-blind study of postoperative analgesia in 40 patients after intracranial neurosurgery. Eighteen patients received codeine phosphate 60 mg and 18 morphine sulphate 10 mg, both by intramuscular injection; 4 patients (10%) required no analgesia. Both drugs provided analgesia within 20 min of injection but morphine was more effective than codeine beyond 60 min (p = 0.01). Fewer doses of morphine than codeine were required (p = 0.003). Nine patients requested one dose of morphine and 9 two doses. Seven patients required three doses of codeine and 1 patient required four doses. Neither drug caused respiratory depression, sedation, pupillary constriction or unwanted cardiovascular effects. We conclude that, in the doses used, morphine is a safe alternative to codeine for analgesia after neurosurgery and has a more persistent action.     

Evaluation of a pilot regimen for postoperative pain control in patients receiving oral morphine pre-operatively

Postoperative analgesia in patients who receive regular oral opioids pre-operatively is frequently suboptimal. To improve management we introduced a regimen using subcutaneous diamorphine infusions with incremental doses. Infusion doses were calculated as half the daily pre-operative dose of oral morphine with the increments as one-sixth of the infusion dose. Results were recorded on the first two postoperative days before (n = 13) and after (n = 23) commencing the new regimen. The percentage of patients reporting severe pain at rest and on movement were significantly reduced by the new regimen (54% and 69% vs. 13% and 40%, respectively) since the opioid dose as a percentage of the pre-operative dose was significantly higher (160% vs. 352%). There were no instances of excessive sedation or slow respiratory rate in any patient. The use of the regimen has resulted in greater doses of opioids being administered with fewer patients in severe pain without significant complications.     

The effects of continuous intravenous naloxone on epidural morphine analgesia

Forty-five patients undergoing Caesarean section under epidural anesthesia with bupivacaine were randomly allocated to three groups. Group 1 received 4 mg of epidural morphine immediately postoperatively and 2 mg naloxone by intravenous infusion for 12 hours postoperatively; group 2 was treated as group 1 but without naloxone infusion; group 3 received 10 mg morphine intramuscularly and 20 ml epidural saline after delivery of the baby. Epidural morphine 4 mg produced better postoperative analgesia than 10 mg of morphine intramuscularly (p less than 0.001) and the intravenous infusion of naloxone did not ablate the analgesic effects of epidural morphine. The incidence of itching and vomiting was higher in the epidural opioid groups (p less than 0.05) and intravenous naloxone, although it reduced the severity of the itching, did not reduce its overall incidence. Respiratory depression was not detected in any of the three groups.     

A double-blind comparison of epidural ketamine and diamorphine for postoperative analgesia

Twenty patients who had abdominal hysterectomy under general anaesthesia were randomly assigned to receive either epidural ketamine (30 mg), or epidural diamorphine (5 mg) peri-operatively and on first request for analgesia. Failure to obtain satisfactory analgesia with one of the agents was treated by epidural administration of the other. Pain was assessed by an independent observer, and by the patient using a visual analogue scale. The mean (SD) pain score on recovery from general anaesthesia, on a scale of 0-4, was 2.9 (1.2) for the ketamine group and 1.0 (1.0) for the diamorphine group (p less than 0.01). The mean (SD) time to first request for analgesia was 272 (206) and 72 (41) minutes in the diamorphine and ketamine groups respectively (p less than 0.01). All patients in the diamorphine group obtained adequate analgesia, but all patients in the ketamine group were changed to epidural diamorphine. Epidural ketamine does not appear to be a sufficiently effective alternative to epidural diamorphine for routine use in postoperative pain.     

A mixture of alfentanil and morphine for rapid postoperative loading with opioid: theoretical basis and initial clinical investigation

Pharmacokinetic modelling of estimated central nervous system concentrations was used to devise the optimal mixture of morphine and alfentanil for the treatment of postoperative pain. Modelling revealed that an intravenous opioid pain protocol using an alfentanil-morphine mixture in the proportions 0.75 : 10 mg would provide a profile of analgesia of rapid onset, yet slow offset. The regimen was evaluated in 58 patients in the recovery ward who were randomly allocated to receive analgesia using pain protocols with either morphine or the mixture. Groups were well matched for age, weight and initial pain scores. The mean (SD) time to patient comfort was 27.6 (20.2) min for the mixture and 41.2 (18.6) min for morphine (p = 0.01). Multiple regression analysis revealed that that initial pain score (p = 0.009) and drug group (p = 0.02), but not age, weight or gender were independent predictors of the time to comfort. Drug group was not a significant predictor of adverse effects.     

Intrathecal morphine for the relief of post-hysterectomy pain - a double-blind,dose-response study

Eighty patients undergoing total abdominal hysterectomy under general anaesthesia were randomly divided into four groups to study the dose-response relationship of intrathecal morphine (0, 0.1, 0.3 and 0.5 mg) for postoperative pain relief. Pain scores, as assessed by using the visual analogue scale, revealed that intrathecal morphine provided long-lasting pain relief, was most effective after 0.3 mg and significantly reduced the need for supplementary analgesics (P<0.05). There was no difference as regards the quality of analgesia or the use of supplementary analgesics between the 0.3 and 0.5 mg groups. Adequate pain relief was not evident after a 0.1 mg dose. There was no incidence of respiratory depression in any of the patients in this study. The incidence of side effects was least following 0.3 mg intrathecal morphine, which we consider to be the optimum dose.     

Controlled comparison of nalbuphine and morphine for post-tonsillectomy pain

A controlled investigation was conducted to compare the effectiveness of morphine and nalbuphine in the prevention of pain and restlessness after tonsillectomy in children. Sixty children between 4 and 12 years old were randomly allocated to receive intramuscular morphine 0.2 mg/kg, nalbuphine 0.3 mg/kg or no medication approximately 5 minutes before the conclusion of surgery. Pain and restlessness were assessed 1 and 2 hours after injection, and side effects were recorded. The assessments were made double-blind. Both nalbuphine and morphine decreased restlessness and pain 1 hour (p less than 0.01) and 2 hours (p less than 0.05) after surgery. No significant differences were found between the two groups of patients who received opioids. Both nalbuphine and morphine caused more drowsiness than placebo 2 hours after surgery (p less than 0.001). Other side effects were uncommon. Nalbuphine may offer advantages compared with morphine in regard to safety and convenience of use for the treatment of post-tonsillectomy pain in children.