The influence of patient characteristics on the requirements for postoperative analgesia

The requirements for analgesia after upper abdominal surgery were evaluated in 100 patients who received morphine by way of a patient-controlled analgesia system. Hourly and cumulative 24-hour requirements were analysed for possible correlations with patient characteristics and for the patterns of consumption throughout the 24-hour study period. The level of pain relief was assessed by linear analogue pain scores at 4-6 hours and 24 hours. Male patients (n = 46) required significantly more morphine than female patients (n = 54) to achieve similar levels of pain relief (p less than 0.05). There was an inverse correlation between age and morphine consumption in both males and females (r = -0.684, p less than 0.00005 and r = -0.502, p less than 0.00005 respectively). No correlation was found between morphine consumption and patient weight. The pattern of hourly morphine consumption appeared to follow a diurnal rhythm, with peak times of demand at 0900 and 2000 hours. The variations in requirements for analgesia among patients and with time of day should be taken into account when a regimen for postoperative analgesia is prescribed.     

Caudal analgesia for perianal surgery

Seventy-three patients undergoing elective perianal surgery were randomly divided into a control group, a group who received a caudal injection of 20 ml bupivacaine 0.5% plain and a group who received diamorphine 2.5 mg in 10 ml normal saline by caudal injection; a comparison was then made of postoperative analgesia requirements. The bupivacaine group had better analgesia than the control group for the first 8 hours, after which there was no difference. The diamorphine group had better analgesia than the control group for the first 24 hours postoperatively. Side effects were less in the diamorphine group than the control, or the bupivacaine group. In particular, 41% of the bupivacaine group complained of some degree of urinary retention and one patient required temporary catheterisation. It is concluded that caudal diamorphine gives good postoperative analgesia for perianal operations, particularly when motor blockade is not wanted by the surgeon.     

Diclofenac in combination with opiate infusion after joint replacement surgery.

The effect of intramuscular diclofenac or placebo on analgesia obtained and on opiate and antiemetic requirements was observed in a randomised double-blind study of sixty patients receiving continuous intravenous papaveretum. Those patients receiving diclofenac required less papaveretum (P = 0.001) than those receiving placebo. They also had lower visual analogue pain scores (VAS) at four hours (P less than 0.05) and decreased requirement for antiemetics (P less than 0.02). No gastrointestinal complications were observed in either group and blood loss did not differ significantly between the two.     

A comparison of nalbuphine with fentanyl for postoperative pain relief following termination of pregnancy under day care anaesthesia

A double-blind investigation was undertaken to compare the efficacy of nalbuphine and fentanyl in the prevention of pain after day case termination of pregnancy. Forty patients were allocated randomly to receive nalbuphine 0.25 mg/kg or fentanyl 1.5 micrograms/kg immediately before induction of anaesthesia. The patients completed scores for pain and nausea, and performed a reaction time test to assess recovery. An observer assessed patient appearance at 1, 2 and 4 hours postoperatively. Patients who received nalbuphine had significantly lower pain scores at 1 hour (p less than 0.01) and 2 hours (p less than 0.05) and required significantly (p less than 0.05) less postoperative analgesia. No significant differences were found between the groups for incidence of nausea or for observer assessment of appearance. There was some evidence of psychomotor impairment at 2 hours in the nalbuphine group. Freedom from Controlled Drug Act regulations and improved analgesia with nalbuphine, render it more satisfactory for day case surgery than the more commonly used fentanyl.     

A randomised double-blind study of interpleural analgesia after cholecystectomy

Continuous interpleural analgesia provided by 4 hourly injections of 20 ml bupivacaine 0.5% with adrenaline 5 micrograms/ml was compared with placebo in a randomised, double-blind study after cholecystectomy. All patients self-administered intravenous morphine using a patient-controlled analgesia device. There was a highly significant difference in mean morphine consumption between the groups (72 mg as compared with 22 mg). Visual analogue pain scores tended to be lower in the bupivacaine group throughout and this was significant at 2 hours. Respiratory function measurements were not significantly different between the groups. The mean peak venous plasma bupivacaine concentration after the sixth dose was 3.03 micrograms/ml and no symptoms suggestive of local anaesthetic toxicity occurred. It is concluded that this regimen can provide effective and continuous analgesia after cholecystectomy and that combined administration of interpleural bupivacaine and systemic morphine is more effective than morphine alone in the immediate postoperative period. The doses of bupivacaine required for optimal use of the technique lead to significant total plasma bupivacaine concentrations within 24 hours.     

Acute opiate tolerance and postoperative hyperalgesia after a brief infusion of remifentanil managed with multimodal analgesia

Postoperative analgesia may be complicated by the occurrence of acute opiate tolerance and hyperalgesia. We present the case of a patient who underwent gynecological surgery that was complicated by intense pain in the immediate postoperative period. The pain was attributed to the development of acute opiate tolerance caused by the brief infusion of a high dose of remifentanil. The opiate tolerance was complicated by tactile hyperalgesia at the site of the surgical wound. Pain management with the usual dose of nonsteroidal anti-inflammatory drugs associated with a high dose of morphine (50 mg administered in less than 2 hours) produced no analgesic or adverse effects. The pain was finally brought under control by epidural perfusion of ropivacaine and fentanyl and subsequently maintained with multimodal analgesia.     

The Triservice anaesthetic apparatus

Sixty male patients undergoing limb surgery were anaesthetised using a drawover technique with the Triservice apparatus. They were randomly allocated to receive trichloroethylene and one of three other volatile agents (halothane, enflurane or isoflurane) after thiopentone induction. Signs of inadequate anaesthesia were noted. The incidence of such signs was not significantly different in the three groups. Similarly, no qualitative difference could be demonstrated in the immediate recovery, but the recovery time was significantly shorter with enflurane.     

Double-blind comparison of epidural diamorphine and intramuscular morphine after elective Caesarean section, with computerised analysis of continuous pulse oximetry

A randomised, double-blind comparison of the efficacy, duration of action and side effects of two analgesic regimens following elective epidural Caesarean section is described. Patients received epidural diamorphine 3 mg or intramuscular morphine 10 mg in the immediate postoperative period. Time to next analgesia was longer after epidural diamorphine (11.0 hours) compared to intramuscular morphine (6.5 hours) (p less than 0.05). In addition, a greater number of patients in the diamorphine group had a pain score less than 2.5 cm at 5 hours (p less than 0.05). However, more patients in the diamorphine group required catheterisation and suffered emetic sequelae, whereas more patients in the morphine group were sedated at 8 hours. Ten patients in each group had continuous pulse oximetry performed overnight after administration of the trial medications. Neither group demonstrated evidence of hypoxia.     

A comparison of halothane and trichloroethylene with isoflurane. A study of drawover air anaesthesia with the Triservice anaesthetic apparatus

Induction and recovery times were not significantly different between two groups that received halothane with trichloroethylene and isoflurane, respectively. Maintenance of anaesthesia and analgesia was also satisfactory. Isoflurane resulted in a higher heart rate (p less than 0.01), a lower respiratory rate (p less than 0.01) and a higher inspired oxygen concentration (p less than 0.05). Respiration may be more efficient. Other potential advantages of isoflurane for anaesthesia in the field are discussed. Despite the fact that it is 15 times more expensive, the use of isoflurane as sole agent is recommended.     

Naloxone does not antagonize the analgesic effects of inhalation anesthetics

A previous demonstration that the ratio of analgesic to anesthetic endpoints is not constant across inhalation anesthetic agents implies that more than one mechanism of action may be operant in general anesthesia. We hypothesized that the endogenous opiate systems might account for this observed disparity in ratios. The tail flick ED50 (TFED50) in response to a heat stimulus, as an index of analgesia, and MAC as an index of anesthesia, were determined in rats treated with either saline or naloxone, 20 mg/kg, and exposed to halothane, enflurane, or isoflurane. Our findings confirmed those of Deady et al., showing a lack of uniformity of ratios of TFED50/MAC, with values of 0.90 +/- 0.03 for halothane, 0.80 +/- 0.04 for enflurane, and 0.70 +/- 0.04 for isoflurane. Naloxone had no effect on TFED50, MAC, or their ratio. If the endogenous opiate system were involved in the analgesic effect of general anesthetics, naloxone would have affected the ratios. We conclude that opiate systems are not involved in the analgesic action of general anesthetics.     

Epidural buprenorphine for pain relief after spinal decompression

We report a prospective double-blind trial of the efficacy of a single epidural dose of buprenorphine on pain after spinal decompression. Postoperative pain was assessed by a linear analogue pain chart and by the additional requirement for analgesia. The patients receiving buprenorphine were significantly more comfortable (p less than 0.005) and required less analgesia in the first 12 hours after operation (p less than 0.05) than the control group. This simple procedure is recommended as an effective and safe method of reducing pain.     

Single-breath induction of anesthesia: comparison of enflurane and sevoflurane

In this study induction of anesthesia using the single-breath technique with either enflurane or sevoflurane in oxygen was compared. Each group consisted of 16 unpremedicated volunteers who breathed approximately 1.7 minimum alveolar concentration (MAC) equivalents of either vapor. There were no significant differences in the cardiovascular and respiratory variables monitored. The induction of anesthesia with enflurane (141±41 s) required significantly more time than with sevoflurane (118±25 s). The enflurane group was associated with significantly more problems during induction, and showed moderate or sometimes severe excitatory movements of the extremities and/or coughing. Subjects in the enflurane group described the induction of anesthesia as less pleasant than in the sevoflurane group. We concluded that enflurane was less suitable for single-breath induction of anesthesia compared with sevoflurane.     

Hepatic metabolic ability during anasthesia Evaluation of antipyrine half-lives and their relation to enflurane metabolism

The antipyrine (phenazone) half-life was determined in 20 surgical patients to discover whether there are changes in hepatic metabolic rate during or immediately after anaesthesia compared with the pre-anaesthetic rate. Nine patients received enflurane (mean duration 8.6, SD 2.0 hours) and six patients had a balanced anaesthetic without enflurane (duration 4.4, SD 3.3 hours). A further five patients received a spinal anaesthetic with bupivacaine. The changes in antipyrine half-life were inconsistent, and there was no evidence of competitive metabolic inhibition by general anaesthesia. Antipyrine half-lives did not correlate with serum fluoride levels or urinary fluoride excretion in the case of enflurane. The mean serum inorganic fluoride concentration rose to 29 mumol/litre, and two patients had potentially nephrotoxic concentrations (64 and 50 mumol/litre) after 8 hours of exposure to enflurane though without any evident harmful effects.     

Ventilatory response during halothane and enflurane anaesthesia

In six children with body weights between 11.4-18.7 kg, minute ventilation, tidal volume, respiratory rate, end-tidal CO2 concentration and CO2 elimination were measured during both CO2 free breathing and CO2 breathing due to low fresh gas flows (maximal inspired CO2 about 2%) or the addition of CO2 from Rotameters (mean inspired CO2 about 1.5%) during both halothane and enflurane anaesthesia. All patients were undergoing hypospadias repair, received caudal analgesia prior to surgery and were intubated and allowed to breathe halothane/enflurane in O2/N2O (FIO2 0.5) spontaneously through a modified T-piece system (Mapleson F). End-tidal CO2 concentrations were similar with both agents during CO2-free breathing and did not increase during CO2 breathing because of increased minute ventilation, of the same magnitude with both agents, which was achieved by larger tidal volumes. Respiratory rates were unchanged. No differences were found between halothane and enflurane at the light levels of general anaesthesia made possible by combination with caudal block.     

Postoperative nefopam and diclofenac Evaluation of their morphine-sparing effect after upper abdominal surgery

The aim of the study was to assess the relative morphine-sparing effects of nefopam and diclofenac when used singly or in combination after upper abdominal surgery. Eighty-four patients of ASA grade 1 or 2 were allocated randomly to one of three groups. Group A received nefopam 20 mg by intramuscular injection 6 hourly after surgery for the 24-hour study period. Group B received diclofenac 75 mg 12-hourly and placebo injections at 6 and 18 hours after surgery. Group C received both 6-hourly nefopam and 12-hourly diclofenac. Supplemental analgesia was given on demand via a patient-controlled analgesia system which delivered intravenous morphine. Morphine requirements in the diclofenac group were significantly lower than in either of the other groups (p less than 0.01). Patients who received the combination of nefopam and diclofenac required significantly less morphine than those who received nefopam alone (p less than 0.01). Pain scores assessed 6 hours after surgery were significantly lower in the diclofenac and combination groups compared with the nefopam group (p less than 0.01).     

Simultaneous laparoscopic resection of rectal cancer and liver metastasis

Simultaneous resection of colorectal tumor and liver metastasis has been advocated because of the benefits of avoiding a second operation, reduced morbidity, shorter treatment time, and similar outcomes. We report a case of simultaneous laparoscopic resection. The operative time was 350 minutes and the estimated blood loss was 500 mL. The patient required parenteral analgesia for less than 48 hours. Flatus was passed on postoperative day 3, and a solid diet was resumed on postoperative day 5. He was fully mobile on postoperative day 4 and was discharged 3 days later. With the advance of laparoscopic technology and technique, simultaneous resection becomes an attractive option.     

Alterations in splenic lymphocyte subpopulations and increased mortality from sepsis following anesthesia in mice

The authors evaluated the potential of a variety of anesthetics in mice to produce subsequent alterations in host defenses. Specific monoclonal antibodies and immunofluorescent microscopy were used to enumerate splenic helper/inducer: suppressor/cytotoxic lymphocyte ratios (HSR), and resistance to bacterial challenge was evaluated by a cecal ligation and puncture (CLP) model. Two hours of anesthesia with the intravenous agents ketamine and pentobarbital and with the inhalational agents isoflurane, enflurane, halothane, and halothane-nitrous oxide, were utilized. All anesthetics produced marked depression in the HSR, measured 24 h postanesthesia (P less than 0.05); with all agents, helper T-cell populations were decreased and suppressor populations increased. The HSR remained depressed 72 h postanesthetic, following both ketamine and halothane anesthesia (P less than 0.05). A dose-response curve was determined with enflurane; increasing the anesthetic time from 1 to 6 h resulted in progressively greater depression of the HSR 24 h later. Changes in lymphocyte subtypes of similar magnitude were found in mice after burn injury or hind limb crush injury and amputation, whereas simple laparotomy did not produce such changes. Serum corticosterone levels were not elevated 24 h post-anesthetic with enflurane, suggesting that the alterations were not nonspecific stress reactions. Resistance to sepsis was determined by measuring survival for 96 h after CLP. With CLP performed 24 h following 2 h anesthesia, mortality was increased from normal: control mortality 36.3%; ketamine 65.0% (P less than 0.023); isoflurane 69.5% (P less than 0.006); enflurane 84.2% (P less than 0.0002).(ABSTRACT TRUNCATED AT 250 WORDS)     

Randomized comparison of outcome after propofol-nitrous oxide or enflurane-nitrous oxide anaesthesia in operations of long duration

A randomized, prospective, comparative study was performed to evaluate induction characteristics, haemodynamic changes and recovery in 60 ASA I-II patients undergoing mainly gynaecological laparotomies with either propofol or thiopentone-enflurane anaesthesia. The propofol group (n = 30) received 2 mg.kg-1 propofol for induction of anaesthesia followed by propofol infusion. The thiopentone-enflurane group (n = 30) received thiopentone 4 mg.kg-1 for induction followed by enflurane (0.5-2 per cent). All patients received nitrous oxide (66 per cent] in oxygen begun one minute after tracheal intubation, and fentanyl (1.5 micrograms.kg-1) four minutes prior to induction. Other drugs administered during or after anaesthesia were similar among the groups. Haemodynamic measurements were similar between propofol and enflurane groups except after tracheal intubation when the mean arterial pressure was lower in the propofol group (P less than 0.05). The propofol group had significantly less (P less than 0.01) emesis in the recovery room than the enflurane group. The propofol group experienced significantly less (P less than 0.05) dizziness, depression/sadness and hunger than the enflurane group in the postoperative period as assessed with a visual analogue questionnaire. We conclude that propofol provided better outcome than enflurane in terms of these nonvital but annoying outcome measures after relatively long intra-abdominal operations.     

Buprenorphine added to the local anesthetic for brachial plexus block to provide postoperative analgesia in outpatients

BACKGROUND AND OBJECTIVES: Over the past 10 years, several studies have suggested that the addition of certain opiates to the local anesthetic used for brachial block may provide effective, long-lasting postoperative analgesia. One of these studies indicated that the agonist-antagonist, buprenorphine, added to bupivacaine provided a longer period of postoperative analgesia than the traditional opiates, but in this study, it is impossible to determine the relative contributions of the local anesthetic and the opiate to the postoperative analgesia because of the extremely long duration of the anesthesia provided by the local anesthetic, bupivacaine. By repeating the study using a local anesthetic of a shorter duration, the present study delineates more clearly the contribution of the buprenorphine to postoperative analgesia when added to a shorter-acting local anesthetic. METHODS: Forty, healthy, consenting adult patients scheduled for upper extremity surgery were enrolled in the study. Premedication was provided by intravenous midazolam 2 mg/70 kg and anesthesia by a subclavian perivascular brachial plexus block. The patients were assigned randomly to 1 of 2 equal groups based on the agents used for the blocks. The patients in group I received 40 mL of a local anesthetic alone, while those in group II received the same local anesthetic plus buprenorphine 0.3 mg. The study was kept double-blind by having 1 anesthesiologist prepare the solutions, a second anesthesiologist perform the blocks, and a third anesthesiologist monitor the anesthesia and analgesia thereafter, up to and including the time of the first request for an analgesic medication. The data were reported as means (+/- SEM), and differences between groups were determined using repeated measures of analysis of variance (ANOVA) and chi(2), followed by the Fisher exact test for post hoc comparison. A P value of less than.05 was considered to be statistically significant. RESULTS: The mean duration of postoperative pain relief following the injection of the local anesthetic alone was 5.3 (+/- 0.15) hours as compared with 17.4 (+/- 1.26) hours when buprenorphine was added, a difference that was statistically (and clinically) significant (P <.0001). CONCLUSIONS: The addition of buprenorphine to the local anesthetic used for brachial plexus block in the present study provided a 3-fold increase in the duration of postoperative analgesia, with complete analgesia persisting 30 hours beyond the duration provided by the local anesthetic alone in 75% of the patients. This practice can be of particular benefit to patients undergoing ambulatory upper extremity surgery by providing prolonged analgesia after discharge from the hospital.     

Droperidol prevents and treats nausea and vomiting after enflurane anaesthesia

One hundred and twelve women undergoing elective orthopaedic surgery under enflurane anaesthesia were given, in a double-blind random fashion, 2.5 mg of droperidol i.m. before anaesthesia, or 1.25 mg of droperidol or a saline placebo i.v. at the end of anaesthesia in an attempt to prevent post-operative vomiting. The administration of droperidol 1.25 mg (for those receiving initially 1.25 mg of droperidol) or saline (for those receiving initially 2.5 mg of droperidol or saline) was repeated i.m. during the 24 post-operative hours in a blind manner if the patient complained of nausea, retched or vomited. Significantly fewer patients (P less than 0.05) given i.m. or i.v. droperidol had emetic symptoms than patients given saline. Furthermore, 51% of the patients given saline needed additional doses of saline, whereas only 27% of the patients given i.m. and 36% of the patients given i.v. droperidol required a second dose (P less than 0.05 between groups). More of the patients given saline (23%) than those given droperidol (8% to 9%), as a blind drug (P less than 0.05), needed to be given additional droperidol as a known anti-emetic because of the failure of the blind drug to prevent or treat symptoms. It is concluded that droperidol given either as a single dose of 2.5 mg i.m. or in repeated doses of 1.25 mg i.v. is effective in the prevention and treatment of post-operative nausea and vomiting after enflurane anaesthesia.