Continuous infusion of epidural morphine to relieve postoperative pain. Protocol and results

We have evaluated the efficaciousness and side effects of continuous administration of morphine by lumbar epidural route for relieving postoperative pain in major surgery of the abdomen and orthopedic surgery. Lumbar epidural catheters were placed to 25 patients (mean age, 52 years) before induction of general anesthesia. All patients received a 4 mg bolus dose of morphine sulfate 1 hour before finalization of general anesthesia and subsequently they were placed on a continuous infusion of morphine sulfate at 0.3-1 mg/h. All patients achieved analgesia which maintained then pain-free and allowed early ambulation and initiation of active respiratory physiotherapy. Duration of continuous analgesia varied from 3 to 5 days. No patient presented respiratory depression; four presented nausea and eight had urinary retention. We believe that continuous epidural infusion of morphine is efficacious and safe for the treatment of acute postoperative pain in patients undergoing abdomen major surgery and orthopedic surgery.     

Perineural resiniferatoxin prevents hyperalgesia in a rat model of postoperative pain

Resiniferatoxin (RTX) is a vanilloid agonist with a unique spectrum of activities. Vanilloids bind to the transient receptor potential ion channel subtype 1, a nonselective cation ionophore important in the integration of different noxious signals. Vanilloid agonists selectively decrease sensitivity to noxious stimuli. In this study, we sought to determine whether perineural RTX prevents hyperalgesia in a model of incisional pain. In a rat model, RTX was administered percutaneously to the sciatic and saphenous nerves before the plantar incision. The withdrawal response to von Frey filaments, the struggle response to pressure on the paw, and pain scoring based on weight bearing were measured before RTX and at various intervals for 8 days after RTX. A percutaneous injection of RTX (0.0003%) to the sciatic (0.1 mL) and saphenous (0.05 mL) nerves completely prevented incisional hyperalgesia. Two hours after incision, the withdrawal threshold was 51 mN without and 456 mN with RTX (P < 0.0001). RTX also prevented the incision-induced decrease in struggle threshold and abolished the pain behavior associated with weight bearing. We conclude that RTX provides a type of neural blockade when postoperative pain is abolished and that nonpainful sensations and motor functions are preserved.     

Intrathecal morphine for postoperative pain]

At the beginning, the way intrathecal morphine was used for postoperative pain relief was quite unfortunate, because the doses derived from experience with morphine-tolerant cancer patients were considerably too high and respiratory depression occurred frequently. Subsequent dose-finding studies showed that the doses of morphine used initially could be reduced by a factor of ten without loss of the analgesic effect and with a marked reduction in side-effects. No respiratory depression has been reported when doses below 0.1 mg morphine are used. METHOD. In this prospective study the effect of 0.06 to 0.08 mg intrathecal morphine, mixed with the local anaesthetic for spinal anesthesia, was investigated in surgical patients aged 21 to 81 years, ASA grade I or II, scheduled for orthopaedic operations or herniorraphies. Thirty unpremedicated patients were enrolled in the study and were, after informed consent, randomly allocated to a control group without morphine or to a morphine group. The analgesic effect was assessed by the time interval between the administration of the spinal anaesthesia and the first demand for an analgesic medication. The mood state was evaluated with the adjective checklist of Janke and Debus 6 h after the spinal anaesthesia. RESULTS AND DISCUSSION. In the control group half of the patients asked for an analgesic medication within 275 min (median) after the spinal anaesthesia, and all patients within 420 min, whereas in the morphine group half of the patients asked for an analgesic within 1170 min (median). Seven patients had not required an analgesic at the termination of the observation period 20 h after the spinal anaesthesia. The mood status showed no difference between the two groups, in particular, no dizziness or drowsiness after morphine. There was no difference in the incidence of side-effects such as nausea or urinary retention between the two groups. Pruritus was not reported spontaneously but was found upon questioning in five patients. It was in no case disturbing. CONCLUSIONS. Morphine (0.06 to 0.08 mg) mixed with the local anaesthetic for spinal anaesthesia provided for an analgesia of more than 20 h duration in half of the patients. This technique is safe, simple, reliable and virtually free of side-effects. No particular supervision due to the administration of intrathecal morphine is necessary in this dose range if systemic opiates are avoided. If the analgesia is unsatisfactory, a non-opioid analgesic is recommended.     

蛛网膜下隙注射吗啡术后镇痛

目的　探讨蛛网膜下隙注射吗啡术后镇痛的临床效果及不良反应。方法　ASAⅠ～Ⅱ级 6 0例择期妇科手术病人 ,随机分为两组 ,每组 30例 ,均采用腰麻 硬膜外联合阻滞。腰麻用药为0 5 %重比重布比卡因 10mg ,然后硬膜外腔置管。研究组于腰麻药中加入吗啡 0 2 5mg ,对照组则于硬膜外腔注射吗啡 2mg。术后行视觉模拟评分 (VAS)、Ramsay镇静评分、BCS(Bruggrmanncomfortscale)舒适评分并观察不良反应发生情况。结果　蛛网膜下隙吗啡组术后完全无痛时间和持续镇痛时间明显长于硬膜外吗啡组 ,VAS评分明显低于硬膜外吗啡组 (P <0 0 5或P <0 0 1)。Ramsay评分和BCS评分明显高于硬膜外吗啡组 (P <0 0 5或P <0 0 1)。蛛网膜下隙吗啡组术后不良反应发生率明显增加 (P <0 0 5 )。结论　蛛网膜下隙注射吗啡镇痛效果确切、持续时间长 ,但不良反应发生率较高于硬膜外吗啡镇痛     

Epidural morphine for postoperative pain relief in children

Epidural morphine for postoperative pain relief is in general use, and has proved to be very efficient in adults. The epidural technique and the use of epidural morphine are much less frequent in children. For 2 years we have prospectively followed 76 children who had epidural morphine for postoperative pain relief after major abdominal surgery. The age distribution was from newborn to 13 years, with a median age of 12 months. It was estimated that 94% of the patients had good analgesia for the first 24 postoperative hours and no other opioids were given. The side effects were few, but one case of respiratory depression was seen and 20% of the children had pruritus. There were four dural punctures and three catheters slipped out accidentally, but otherwise the treatment was continued as long as it was considered necessary (1–11 days). The use of postoperative ventilatory support decreased during the investigation. We observed a change in the sleeping pattern with an increased number of sleep–induced myoclonia during the administration of epidural morphine. In conclusion, the use of epidural morphine in children for postoperative pain relief is very efficient. The minimal effective dose has not been established as yet, but 50 Hg/kg every 8 h, supplemented with small doses of bupivacaine, provides excellent analgesia in the immediate postoperative period after major abdominal surgery. The side effects are few, but the risk of respiratory depression is always present and observation in the intensive care unit or recovery for the first 24 h is strongly recommended.     

Continuous morphine infusion for postoperative pain in children

Previous erratic use of intermittent intramuscular and intravenous morphine or pethidine for postoperative analgesia prompted a prospective trial of continuous intravenous morphine delivered by an infusion pump. The rate was adjusted to keep the patient free of pain--as assessed by observation in the infant and enquiry in the older child. Serum morphine levels were monitored for the first 36 hours. The results of a cohort of 20 patients (aged 3 months-12 years) are presented. Thanks to positive parental and nursing staff support, and absence of complications, administration of postoperative analgesia with continuous intravenous morphine infusion is now standard practice in this unit.     

Epidural droperidol and morphine for postoperative pain

Epidural morphine is effective in the treatment of postoperative pain, but the incidence of associated side effects is high. To assess a potential reduction of opioid side effects by droperidol, 4 mg morphine with either placebo or 2.5 mg droperidol was injected epidurally in a double-blind, randomized, postoperative trial. Forty patients undergoing hip replacement surgery were studied. The overall incidence of side effects during the first 24 h in the group receiving droperidol and morphine was less than 50% of that in the group receiving placebo and morphine (P less than 0.008). Pruritus, emesis, nausea, urinary retention, and hypotension were diminished in the group with droperidol. No significant differences in duration or quality of analgesia were seen. Epidural injection of droperidol did not result in any local or systemic side effects.     

Use of bupivacaine as block to relieve postoperative pain in pediatric orchiopexy and hernia repair

Bupivacaine was utilized for postoperative analgesia in patients undergoing orchiopexy and hernia repair. In a study of 75 pediatric patients, ranging in ages from twelve months to twelve years, who had undergone orchiopexy and hernia repair during a three-year period, 42 received bupivacaine hydrochloride as a local infiltration block anesthesia to relieve postoperative pain; 33 patients did not receive bupivacaine. Patients receiving bupivacaine had less postoperative pain and were more comfortable when leaving the hospital within a few hours after surgery.     

Lumbar epidural morphine in humans and supraspinal analgesia to experimental heat pain

BACKGROUND: Epidural administration of morphine is a common analgesic technique to manage pain. Morphine spreads from the epidural space to the cerebrospinal fluid and then rostrally, causing side effects mediated by the brain stem. However, data on the rostral spread of morphine-mediated analgesia are sparse. This study examined the rostral spread of analgesic effects on heat and electrical pain after epidural administration of morphine. METHODS: In a randomized, double-blinded, placebo-controlled, crossover study, 5 mg morphine or saline placebo were injected into the lumbar epidural space in nine healthy volunteers. Correct needle placement was confirmed with fluoroscopy. Analgesia to experimental nociceptive heat and electrical stimuli was measured at lumbar (L4), thoracic (T10), cervical (C2), and trigeminal (V2) levels before and 2, 5, 10, and 24 h after epidural injection. Plasma samples for assaying morphine concentrations were drawn before and after each analgesic evaluation. RESULTS: Epidural morphine significantly attenuated experimental heat pain at all dermatomes tested compared with saline placebo. Analgesic effects were significant at L4 after 2, 5, and 10 h, at T10 after 5, 10, and 24 h, and at V2 after 10 h. Electrical pain was attenuated at the lumbar and thoracic but not at the cervical dermatome. Analgesic effects were significant at L4 after 2, 5, and 10 h and at T10 after 5 and 10 h. Morphine plasma concentrations were below the detection limit (1 ng/ml) in eight of the nine subjects 10 h after epidural injection. CONCLUSIONS: Lumbar epidural injection of morphine attenuated cutaneous heat pain up to the trigeminal dermatome during a 24-h observation period. In a clinical context, this implies that some types of pain may be attenuated up to the supraspinal level after lumbar epidural administration of morphine.