These results suggest that the UK Audit Commission (1997) proposed standards of care might be unachievable using current analgesic techniques. The data may be useful in setting standards of care for Acute Pain Services.

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Background. This study examines the evidence from published data concerning the adverse respiratory and haemodynamic effects of three analgesic techniques after major surgery; i.m. analgesia, patient-controlled analgesia (PCA), and epidural analgesia.Methods. A MEDLINE search of the literature was conducted for publications concerned with the management of postoperative pain. Information relating to variables indicative of respiratory depression and of hypotension was extracted from these studies. Over 800 original papers and reviews were identified. Of these papers, 212 fulfilled the inclusion criteria but only 165 provided usable data on adverse effects. Pooled data obtained from these studies, which represent the experience of a total of nearly 20 000 patients, form the basis of this study.Results. There was considerable variability between studies in the criteria used for defining respiratory depression and hypotension. The overall mean (95% CI) incidence of respiratory depression of the three analgesic techniques was: 0.3 (0.1-1.3)% using requirement for naloxone as an indicator; 1.1 (0.7-1.7)% using hypoventilation as an indicator; 3.3 (1.4-7.6)% using hypercarbia as an indicator; and 17.0 (10.2-26.9)% using oxygen desaturation as an indicator. For i.m. analgesia, the mean (95% CI) reported incidence of respiratory depression varied between 0.8 (0.2-2.5) and 37.0 (22.6-45.9)% using hypoventilation and oxygen desaturation, respectively, as indicators. For PCA, the mean (95% CI) reported incidence of respiratory depression varied between 1.2 (0.7-1.9) and 11.5 (5.6-22.0)%, using hypoventilation and oxygen desaturation, respectively, as indicators. For epidural analgesia, the mean (95% CI) reported incidence of respiratory depression varied between 1.1 (0.6-1.9) and 15.1 (5.6-34.8)%, using hypoventilation and oxygen desaturation, respectively, as indicators. The mean (95% CI) reported incidence of hypotension for i.m. analgesia was 3.8 (1.9-7.5)%, for PCA 0.4 (0.1-1.9)%, and for epidural analgesia 5.6 (3.0-10.2)%. Whereas the incidence of respiratory depression decreased over the period 1980-99, the incidence of hypotension did not.Conclusions. Assuming a mixture of analgesic techniques, Acute Pain Services should expect an incidence of respiratory depression, as defined by a low ventilatory frequency, of less than 1%, and an incidence of hypotension related to analgesic technique of less than 5%.

This review examines the evidence from published data concerning the tolerability (indicated by the incidence of nausea, vomiting, sedation, pruritus, and urinary retention), of three analgesic techniques after major surgery; intramuscular analgesia (i.m.), patient-controlled analgesia (PCA), and epidural analgesia. A MEDLINE search of publications concerned with the management of postoperative pain and these indicators identified over 800 original papers and reviews. Of these, data were extracted from 183 studies relating to postoperative nausea and vomiting, 89 relating to sedation, 166 relating to pruritus, and 94 relating to urinary retention, giving pooled data which represent a total of more than 100,000 patients. The overall mean (95% CI) incidence of nausea was 25.2 (19.3-32.1)% and of emesis was 20.2 (17.5-23.2)% for all three analgesic techniques. PCA was associated with the highest incidence of nausea but the emesis was unaffected by analgesic technique. There was considerable variability in the criteria used for defining sedation. The overall mean for mild sedation was 23.9 (23-24.8)% and for excessive sedation was 2.6 (2.3-2.8)% for all three analgesic techniques (significantly lower with epidural analgesia). The overall mean incidence of pruritus was 14.7 (11.9-18.1)% for all three analgesic techniques (lowest with i.m. analgesia). Urinary retention occurred in 23.0 (17.3-29.9)% of patients (highest with epidural analgesia). The incidence of nausea and excessive sedation decreased over the period 1980-99, but the incidence of vomiting, pruritus, and urinary retention did not. From these published data it is possible to set standards of care after major surgery for nausea 25%, vomiting 20%, minor sedation 24%, excessive sedation 2.6%, pruritus 14.7%, and urinary retention requiring catheterization 23%. Acute Pain Services should aim for incidences less than this standard of care.

The new volatile anaesthetic, desflurane (I-653), was administered to 10 healthy, unpremedicated young male volunteers in order to determine its cardiorespiratory effects and the characteristics and acceptability of its inhalation. All volunteers breathed either sub-anaesthetic (1.8% inspired) or anaesthetic (5.4% inspired) concentrations of the anaesthetic without coughing, breath-holding, salivation or other untoward respiratory response. Respiratory minute volume and alveolar ventilation decreased and ventilatory rate increased. Systemic arterial pressure decreased (diastolic more than systolic) and heart rate remained unchanged. Cardiac rhythm remained unaltered, except in one volunteer who experienced a single premature atrial contraction. Volunteers stated that the odour of desflurane was not irritating or unpleasant. Exposure to the agent for approximately 90 min resulted in rapid and clear-headed recovery.