1Department of Anesthesiology, Akita University School of Medicine, 2Department of Anesthesiology and Pain Clinic, Hiraka General Hospital and 3Department of Anesthesiology, Juntendo University School of Medicine, Hondo 1-1-1, Akita City, Akita 010-8543, Japan*Corresponding author
Accepted for publication: April 10, 2001
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Abstract |
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Br J Anaesth 2001; 87: 6335
Keywords: analgesia, postoperative; analgesia, patient-controlled; analgesia, night-time infusion
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Introduction |
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Methods and results |
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An epidural catheter was inserted through the T910 interspinous space into the epidural space. Anaesthetic induction and intubation was performed with i.v. fentanyl, thiopental, and vecuronium bromide. Anaesthesia was maintained with a propofol infusion, sevoflurane, and oxygen in air. Additional intraoperative epidural analgesia was provided with mepivacaine or bupivacaine. No opioids were used during intraoperative anaesthesia.
A PCA pump containing fentanyl 5 µg ml1 and 0.1% bupivacaine was connected to the epidural catheter and started as soon as the patient was extubated. The PCEA alone group received 5-ml bolus on demand, with a lockout interval of 15 min. In addition to the intermittent bolus doses, the PCEA plus infusion group received 2 ml h1 of the bupivacaine/fentanyl mixture during the nights (from 20:00 to 08:00 on the day of surgery and on the first postoperative day (POD1)). During the night or if the patients oxyhaemoglobin saturation by pulse oxymetry (SpO2) was less than 94%, the patient received oxygen via nasal cannula. When the patients complained of unsatisfactory pain relief, 1% mepivacaine 35 ml was injected via the epidural catheter until they were pain free. The anaesthestist and nurse investigators were blinded with respect to the mode of administration.
The number of patient requests for analgesia (demand) was recorded from the pump hourly during the time from the start of the study to 14:00 on the second postoperative day (POD2). We calculated the average hourly consumption that includes the infusion and patient demands during the time from the start of the study to 20:00 on the day of surgery, during the night, and in each 6-h interval during the daytime. VAS pain scores both at rest and on coughing were recorded on a 100-mm linear scale, nausea and pruritus were assessed using a 4-point rating scale (0: none; 1: slight; 2: moderate; 3: severe) and objective motor block was assessed using the Bromage score, at 20:00 on the day of surgery, at 8:00, 14:00, and 20:00 on POD1, and at 8:00 and 14:00 on POD2. Sedation was assessed using a 4-point scale (0: eye open spontaneously; 1: eye open to speech; 2: eye open to shaken; 3: unrousable) at 20:00 on the day of surgery, at 8:00, 14:00, 20:00 on POD1, at 8:00, 14:00 on POD2 and every 12 h during the nights. Verbal rating score for sleep pattern was assessed using a 3-point rating scale (0: slept well without PCEA button press; 1: slept well with PCEA button press; 2: could not sleep despite PCEA button press) at 8:00 on POD1 and POD2. Systolic arterial pressure and ventilatory frequency were measured every 12 h, and more frequently if the systolic arterial pressure was less than 100 mm Hg or the ventilatory frequency rate was less than 10 breaths min1.
Continuous data are reported as mean (SD) and analysed using the unpaired two-tailed t-test and two-way analysis of variance (ANOVA) for repeated measurements. Ordinal data were reported as incidences and analysed using the MannWhitney U-test. Patient characteristics were analysed using the unpaired two-tailed t-test for parametric variables and the chi-squared test for non-parametric variables. Values of P<0.05 were considered statistically significant.
Two patients in each group required additional pain relief and received supplemental epidural boluses of 1% mepivacaine 35 ml. However, hypotension did not occur in any patient after supplemental bolus injection. Patient characteristics and operative procedures were comparable between the two groups.
The mean time from the start of the study to 20:00 on the day of surgery was similar between the two groups. The average hourly demand was lower (P<0.005) in the PCEA plus infusion group than in the PCEA alone group during the night (Table 1). The average hourly consumption drugs did not differ between the two groups during the study period (Table 1). VAS pain scores on coughing were significantly lower (P<0.05) in the PCEA plus infusion group than in the PCEA alone group at 8:00 on POD2. The sleep scores on POD1 in the PCEA plus infusion group were significantly lower than those in the PCEA alone group (P=0.018).
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Comment |
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We thought a night-time infusion to be more desirable than an all-day infusion, which had produced more itching than PCEA alone group in an earlier study.2 The incidence of pruritus did not differ between the two groups in our study.
The use of a night-time infusion in a PCEA regimen caused no increase in the incidence of excessive sedation and respiratory depression in our small study; however, respiratory depression was possible during the periods in which the patients were not disturbed by measurements. This emphasizes the need for careful and repeated assessment by experienced staff.
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References |
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2 Komatsu H, Matsumoto S, Mitsuhata H, et al. Comparison of patient-controlled epidural analgesia with and without background infusion after gastrectomy. Anesth Analg 1998; 87: 90710[Abstract]