Annals of the Royal College of Surgeons of England (1979) vol 6i

ASPECTS OF ANAESTHESIA*

Postoperative analgesia using continuous infusion of papaveretum E N S Fry

FFARCS

Consultant Anaesthetist, North Tees General Hospital, Stockton-on-Tees, Cleveland

Summary hysterectomy (including 4 Wertheim's operA technique of postoperative analgesia using ations), and 3 who had gastric surgery. The patients had oral premedication with continuous intravenous papaveretum with a 20 mg and diazepam 20 mg metoclopramide intravenous derived from previous dosage titration is described. Hourly pain scores, pulse 2 h before operation. General anaesthesia was and respiration rates, and blood pressure read- induced with 2.5% thiopentone 5 mg/kg body ings were recorded. The patients were followed weight and maintained with nitrous oxide 6 up until discharge from hospital. The nature 1/min, olxygen 2 1/min, halothane 1-2%, and and incidence of various complications were pancuronium as required. noted.

Introduction After operation analgesic drugs are usually given intramuscularly by trained nurses when the patient has recovered from anaesthesia. The injection is not repeated until the patient suffers pain or until a set period of time has elapsed. Requirements of papaveretum are only poorly correlated with the patient's age, weight, or operation1 and the analgesic effect of morphine is not related even to its concentration in the serum2. So many patients suffer postoperative pain which causes not only distress but also nausea and vomiting3.

Patients and methods Sixty patients undergoing major abdominal surgery were studied. They gave their informed consent to their inclusion in the study. There were I5 men and 45 women. The mean age was 53.5 (SD I5.3) years, range 2582 years. The mean weight was 62.8 (SD 10.2) kg, range 40-9o kg. The series included I4 patients, 3 of whom were jaundiced, who had operations on the biliary tract, of which 5 were major reconstructions of the bile duct, I3 patients who had operations on the kidney or ureter, I 3 who had resection of large bowel (9 for carcinoma and 4 for inflammatory disease), I2 who had

When analgesia was needed after operation papaveretum was titrated intravenously using boluses of 2 mg at i-min intervals until 8 mg had been given. Thereafter the titration was continued with i mg each minute until the patient said that the pain was relieved and could cough effectively without distress. Naloxone, an opiate antagonist, was available if respiratory depression or coma ensued. It was never required. Ninety minutes after the titration i 1 times the titrated dose of papaveretum, diluted with isotonic saline to 20 ml, was injected over I2 h using a Handley clockwork infusion pump. The infusion was repeated once. An extension set connected to an intravenous line enabled the patient to move both within and out of bed. In 27 cases doxapram was added to both the titration mixture (ioo mg) and to each of the infusions (200 mg). Doxapram is a specific respiratory stimulant that does not antagonise the analgesic action of opiates46. It was given to patients who were over 6o years old or had a history of respiratory disease or reduced pulmonary function. After operation the patients were assessed hourly for appreciation of pain. Four grades were used: o-no pain, i-slight pain, 2 moderate pain, and 3-severe pain. Levels of consciousness were estimated at the same time. Seven trained nurses made the assessments. They had worked together on several previous analgesic studies and had opportunities to

The Editor would welcome any observations on this paper from readers *Fellows and Members interested in submitting papers for consideration with a view to publication in this series should first write to the Editor

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E N S Fry

compare their criteria. Pain was assessed by questioning the patient at rest. If asleep the patient was rated zero. Other observations were made hourly. Pulse rates were measured with the pulse meter of an SE Laboratories memory monitor. Blood pressures were measured to the nearest 5 mm Hg (o.67 kPa) with a Meditron F electronic sphygmomanometer. Respiration rates were measured by counting, using a watch with a second hand. All the patients were followed up until discharge from hospital and any complications observed or noted in the nursing or medical records were collected. Results and discussion Fifty-nine patients required postoperative analgesia. The pain score was 3 (severe) in 8 cases, 2 in 4I, and i in Io immediately before titration of papaveretum. The mean dose of papaveretum used in the titration was I4 (SD 5.5) mg, range 0-32 mg. There was a very low correlation between these doses and the ages and weights of the patients: the correlation coefficient with age was 0.I5 and with weight O.I9. The figures for patients undergoing operations on the biliary tract, hysterectomy, renal operations, and largebowel resection were I 3.4 (SD 6) mg, i I.9 (SD 4.4) mg, I4.9 (SD 5.2) mg, and 15.2 (SD 3.6) mg respectively. The correlation coefficients of dose to weight were 0.14, 0.29, 0.14, and -0.I5 respectively. These differences are significant by Student's t test, but the variation within the groups precludes selection of effective doses for individual cases. The pain scores of 33 patients were zero throughout the first 24 h following titration. Fifteen patients were noted to have slight pain only on 4 occasions or less and Io on 4-12 occasions. One patient had a mean pain score of o.9 and another of I.0, with times of moderate and severe pain. This means that only 2 out of 6o patients felt more than slight pain and then only for a small part of the 24-h period. No patients became comatose. All of them enjoyed periods of sleep lasting for several hours. The next morning all were alert and

co-operative and, except for 3 who had had thoracotomy, sat out of bed for short periods the morning after operation. Thirteen patients (22 7o) vomited or required antiemetic drugs to treat nausea. Five patients developed respiration rates of I 2 and i of io/min. These rates were recorded between midnight and 4 a.m. during sleep. No treatment was given and no signs of inadequate respiration were noted. In each case the rate had increased to at least i6/min at the next assessment. None of these patients had been given doxapram. The slowest respiration recorded in a patient who had been given doxapram was 6/min. Two patients developed a systolic blood pressure of less than ioo mm/Hg (I3.3 kPa). One had undergone protocolectomy and had refused blood and the other had had a perforation of the colon with late peritonitis. Seven patients developed a respiratory complication: 2 bronchopneumonia, i lobar collapse, and 4 productive febrile cough without radiological changes (3 of these had previous chronic productive coughs). Two patients developed paralytic ileus, 3 urinary fistulae, and 7 wound infections, i with wound dehiscence. In no case was either a deep vein thrombosis or pulmonary embolism described in the medical records. By using this technique, especially when doxapram is added, postoperative pain is relieved more quickly and more reliably than by using intramuscular injections and a more even level of analgesia is maintained throughout the first 24 postoperative hours.

References I

Fry, E N S (I977) British Medical Journal, 3, 870.

2 Laitinen, J, Kanto, M, Vapaavoori, M, and Vil-

3 4 5

6

janen, M K (I975) British Journal of Anaesthesia, 47, I 265. Andersen, R, and Krohg, K (I976) Canadian Anaesthetists' Society Journal, 4, 366. Gupta, P K, and Dundee, J W (I974) Anaesthesia, 29, 33. Lees, N W (1976) British Journal of Anaesthesia, 48, I I97. Downing, J W, Jeal, D E, Allen, P J, and Buley, R (I977) British Journal of Anaesthesia, 49, 473.

Postoperative analgesia using continuous infusion of papaveretum.

Annals of the Royal College of Surgeons of England (1979) vol 6i ASPECTS OF ANAESTHESIA* Postoperative analgesia using continuous infusion of papave...
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