I. Tigerstedt

Intravenous morphine and oxycodone for pain after abdominal surgery

Intravenous morphine and oxycodone were given double blind in doses of 0.05 mg/kg after major abdominal surgery to 39 patients. The dosing interval was 5 min, until the patient did not want any further analgesics. Less oxycodone was needed than morphine, both to achieve the “first state of pain relief” (13.2 mg vs. 24.9 mg) and during the whole 2‐h study period (21.8 mg vs. 34.2 mg). The “first state of pain relief” was achieved faster (28 min vs. 46 min) and lasted longer (39 min vs. 27 min) with oxycodone than morphine. Morphine caused more sedation and a greater decrease in the mean arterial blood pressure than oxycodone. In other respects the two opioids were comparable.

Opioid treatment for radiating cancer pain: oral administration vs. epidural techniques

In order to determine the optimal pain treatment for patients with cancer involvement of the brachial or lumbar nerve plexuses, a prospective comparative study was carried out using peroral opioid therapy (SO), epidural opioid by a conventional tunnelled epidural catheter (CE) or an epidural catheter connected to an implanted injection port (Port). Pain relief, measured by a visual analog scale (VAS), was similar and adequate in every group already after the first 24 h. CNS side–effects were less frequent and the Karnofsky performance grades slightly superior in the epidural groups. Occlusion and catheter disconnection complicated the pain therapy of five epidural port patients. Epidural dislocation occurred three times in the conventional epidural group. One local infection in the CE group and two in the Port group were recorded. However, no signs of epidural infection were seen at autopsy. The results suggest that due to a lower incidence of side–effects, epidural catheter techniques are superior to peroral opioid in treating pain in these patients. However, complete pain relief was not achieved in all patients, suggesting neurogenic, non–nociceptive pain components. Both epidural techniques seem suitable for long–term pain therapy. Technical improvements are needed in the epidural catheter and the port. The long–term epidural catheter does not seem to cause any major changes in the histology of the dura mater or the connective tissue of the epidural space.

The efficacy of intravenous indomethacin in prevention of postoperative pain

Since intravenous prophylactic anti‐inflammatory agents have been suggested to reduce or even replace opiates in postoperative pain therapy, we studied the demand for morphine in 45 patients recovering from abdominal surgery who had received a baseline infusion of either indomethacin, morphine or saline placebo. When extubated after inhalational anaesthesia, each patient received an i.v. bolus of either 0.5 mg · kg‐1 indomethacin, 0.07 mg · kg‐1 morphine or saline placebo. Thereafter a 20‐h infusion of the same test analgesic was started, either 0.1 mg · kg‐1· h‐1 indomethacin, 0.03 mg · kg‐1 · h‐1 morphine or saline placebo. For additional analgesia, a patient‐controlled analgesia device (PCA) delivering 5‐mg boluses of morphine was used. For the first 5 postoperative hours, significantly more (P<0.05) PCA morphine was needed in the indomethacin group (35 mg) than in the morphine group (24 mg), while the placebo group demanded mean 30 mg. For equal analgesia (measured by VAS and VRS) between 5–20 h, similar amounts (mean 23 and 19 mg) of PCA morphine were required in the indomethacin and morphine groups, in contrast to the placebo group (mean 40 mg) (P<0.001). Morphine infusion increased the total consumption of morphine by 25% as compared to placebo. We conclude that, following abdominal surgery, the analgesic effect of indomethacin infusion became apparent after the first 5 postoperative hours, thereafter reducing the demand for PCA morphine by about 40%. Continuous morphine infusion diminishes the postoperative demand for PCA morphine, but also increases the total morphine consumption.

Double-blind comparison of transdermal scopolamine, droperidol and placebo against postoperative nausea and vomiting

Since transdermal scopolamine (TS) seems effective against seasickness, we compared its antiemetic effect with intravenous droperidol (DHBP), our routine antidote for postoperative emesis. Ninety–six female patients (ASA I–II) scheduled for short–stay surgery were randomly allocated to three study groups after giving their informed consent. The three groups were as follows: TS adhesive, delivering 140 μg initially and 5 μg/h thereafter + placebo 0.5 ml i.v. 5 min before the end of surgery; transdermal placebo adhesive preoperativcly + DHBP 0.5 ml (1.25 mg) i.v. 5 min before the end of surgery; transdermal placebo+ 0.5 ml placebo i.v. as indicated above. Oxycodone i.m. and glycopyrrolate i.v. were given for premedication together with the test adhesive. Anaesthesia was induced with thiopental and maintained with nitrous oxide and oxygen, enflurane, vecuronium and fentanyl. Neostigmine and glycopyrrolate were administered for reversal. In the recovery room no differences in nausea or vomiting were observed between the groups. Sedation was significantly more marked (P < 0.15–0.0001) after DHBP than after either TS or the placebo. An additional 1.25 mg DHBP was required in 28% of the patients given TS compared with 13% of those given DHBP and 6%, of those given the placebo (P <0.05). During the following 24 h nausea was reported more by the placebo patients (25) than by those on TS (20) or DHBP (15) (P <0.05). However, actual vomiting on the ward did not differ between the groups. Visual disturbances were more frequent after TS (P <0.01). We conclude that prophylactic transdermal scopolamine does not diminish postoperative emetic sequelae.

Postoperative Analgesics for Superficial Surgery. Comparison of Four Analgesics

The efficacy of mild analgesics after 160 various superficial operations was studied by comparing intravenous lysine‐acetylsalicylate (LAS) 1.8 g, Litalginr̀ 4 ml (metamizole = dipyrone 2.0 g+pitophenone 8.0 mg) or paracetamol 0.5 g to oxycodone 4 mg. At 15 min postdrug, oxycodone 4 mg had the best peak effect but this significant (p<0.05) difference to mild analgesics disappeared at 30 min, and thereafter all test analgesics showed an equally low effect. Two‐thirds of the patients anaesthetized without peroperative analgesics needed pain relief when recovering from superficial surgery. The need for pain relief was lowest after varicose vein operations, 40% of the patients as compared to about 70% after other types of superficial surgery. In 42% of the patients requiring pain relief, the test analgesics alone gave sufficient pain relief. The rest needed an additional 5 mg of oxycodone, on average, to be comfortable. The combined use of mild analgesics and oxycodone for adequate pain relief did not seem to reduce the postdrug sedation as compared to oxycodone alone. The results indicate that in traditional clinical dosages LAS, dipyrone or paracetamol can substitute about 5 mgoxycodone but offer sufficient analgesia only in about 40% of the patients recovering from superficial surgery.

Comparison of the analgesic dose-effect relationships of nefopam and oxycodone in postoperative pain.

The analgesic dose‐effect relationship of nefopam was compared in a double‐blind randomised trial with that of oxycodone in immediate postoperative pain. Nefopam 15 mg or oxycodone 4 mg was given every 10 min i.v. (maximum six times) to patients in pain after upper abdominal surgery until their wound pain (scored 0–3) disappeared. The mean pain intensity (PI), initially 2.2 in both groups, decreased by approximately the same extent for up to two doses in both groups (to 1.5 after nefopam 30 mg and to 1.1 after oxycodone 8 mg). Thereafter PI was significantly less in the oxycodone group and diminished almost linearily to 0.1 after the sixth dose (24 mg). In the nefopam group, the PI score fell to 1.1 after the fourth dose (60 mg). This seemed to be the “ceiling” effect since additional doses up to 90 mg did not result in greater pain relief. In the oxycodone group, only two patients (12%) needed maximal dosage (6 times 4 mg), one of them requiring 32 mg of oxycodone. In the nefopam group, 12 patients (75%) needed further pain relief after the maximal dosage (6 times 15 mg). In these patients, oxycodone (maximally 16 mg) gave satisfactory analgesia. Drowsiness and a decrease in the respiratory rate were the principal side‐effects of oxycodone, whereas tachycardia, restlessness, sweating and nausea were more frequent after nefopam.

The Need for Fentanyl Supplementation of N2O‐O2 Relaxant Anaesthesia in Chronic Alcoholics

The demand for intermittent halothane supplementation during N2O‐O2‐relaxant anaesthesia was studied in 25 alcoholics (annual consumption over 15 1 pure alcohol) scheduled for biliary or gastric surgery. The controls were 45 nonalcoholics and 43 patients with an annual consumption of between 1 to 15 1. Thiopental (3 mg/kg/min) was given for induction. After intubation, halothane supplementation was given in 0.5% concentration for 10‐min periods. Standardized criteria for halothane supplementation were various motor and autonomic responses to painful stimuli. Muscular relaxation was kept fairly constant (roughly 90%), as assessed visually with the aid of a peripheral nerve stimulator. The total time for which halothane supplementation was given, expressed as a percentage of the total anaesthesia time, was used as an indication of the need for halothane supplementation. The need for thiopental for induction was not increased to a statistically significant extent in alcoholics, but signs of excitation did occur in 40% as compared with 11% in non‐alcoholics (P < 0.01). The demand for halothane supplementation was higher in alcoholics (47±4.8%, s.e. mean) than in non‐alcoholics (33±2.3%). This difference, however, was partly due to the higher incidence of gastric surgery, which required more supplementation than biliary surgery. Analysis of the different criteria indicating the need for halothane supplementation revealed that an increase in blood pressure or heart rate was more common in non‐alcoholics, whereas motor irritability, sweating and lacrimation were more frequent in alcoholics. Management of the anaesthetic posed no special difficulties in the alcoholics with an estimated mean annual consumption of 32 ± 4 (s.e. mean) litres of absolute alcohol. Three patients (5% of the alcohol consumers) reported dreams or recollections, suggesting that this mode of halothane supplementation does not guarantee an adequate anaesthetic depth. The difficulties and biases associated with this type of analysis are discussed.

Narcotic Analgesics in Postoperative Pain Relief in Adults

Postoperative pain is probably one of the most common forms of acute pain requiring alleviation. In Finland, the number of surgical procedures performed annually is about 340,000 and thus roughly one in every 13 Finns can be expected to suffer each year from postoperative pain (HOW-VIANDER 1979), an incidence closely resembling that reported in the U.S.A. (BUNKER 1976). The severity of postoperative pain and the need for narcotic analgesics depends upon numerous factors and varies greatly. Education and the attitude of environment to pain seem to account for racial and cultural differences, e.g. among subcultures in the U.S.A. ( MERSKEY 1978). Obviously, these factors also change with time and continuously model the degree of suffering, even in the same cultural and ethnic group. On the other hand, these differences are tempered by the considerable individual differences within any one particular group. The aetiology of the individual differences is so far largely unknown but the neuroticism score, for example, seems to correlate with the severity of postoperative pain (PARBROOK et al. 1973). A better understanding of the function of endogenous pain-relieving mechanisms will probably help to explain these individual differences in the near future. In addition to the above factors, the site of surgical incision, the type of operation and the anaesthetic technique are the main determinants of postoperative pain intensity. Thus, thoracotomies, upper abdominal operations and nephrectomies are painful operations, while superficial operations are less painful. Peroperative use of narcotics in high dosages or with a long duration of action, reduces the intensity of immediate postoperative pain. Though it fluctuates, the intensity of postoperative pain shows an overall tendency to decrease with time. It is obvious that if these main determinants of pain are not taken into account and specified when discussing the need, efficacy and hence proper use of postoperative analgesics, much undue confusion will arise.

The effect of buprenorphine and oxycodone on the intracholedochal passage pressure.

The effects of i.v, buprenorphine (0.3 mg) and oxycodone (10 mg) on intracholedochal passage pressure were studied in 20 patients who had undergone surgery of the common biliary tract, prior to the extraction of an indwelling T tube. Informed consent was obtained from all patients, each of whom was given buprenorphine or oxycodone in random order. The intracholedochal passage pressure was measured from the T tube perfused with continuous saline infusion (55 ml/h). Both analgesics significantly (P<0.01) increased the intracholedochal passage pressure after 5 min, with an equal peak increase of about 1.5 kPa at about 7 min. The pressure decline was rapid and similar in both groups: 20 min after administration of the test drug only about 40% of the maximum elevation caused by either drug remained. Thereafter, a slower fall towards the baseline was recorded after both drugs during the remaining 45 min of the study period. The results indicate that buprenorphine can be used with the same indications and precautions as other narcotics for postoperative pain relief in patients who have undergone surgery of the biliary tract.

The Need for Fentanyl Supplementation of N2O-O2Relaxant Anaesthesia in Chronic Alcoholics

In order to find out how the need for analgesic supplementation during N2O‐O2‐relaxant anaesthesia is affected by chronic alcohol consumption, 82 patients with various known alcohol habits were anaesthetized for gastric or biliary surgery. Muscular relaxation was kept constant with the aid of a peripheral neurostimulator, and fentanyl was given in increments of 0.05‐0.1 mg for nociceptive symptoms during the anaesthesia.