RESUMEN
The present study was performed to establish whether analgesic consumption in the first four postoperative hours is a suitable basis for selecting the demand dose and predicting the likely analgesic requirement over the next 20 hours with single-use patient-controlled analgesia (PCA) pumps, and to establish whether this method provides effective pain control. Forty-two patients who had undergone a laparotic gynecological procedure (hysterectomy) were given an electronic PCA pump (Abbott Lifecare, Abbott Laboratories, Abbott Park, IL) for four hours (phase I) with a demand dose of 1 mg piritramide and a lockout period of five minutes for dose titration. Piritramide's potency is comparable with that of morphine. The patients then received single-use PCA pumps (Baxter Infusor/Watch, Baxter, Deerfield, IL) for the next 20 hours (phase II) with a demand dose of 0.75 mg in Group A and 1.5 mg in Group B, depending on whether more or less than 10 mg pritramide had been consumed in phase I. A specially designed electronic recorder was used to measure the exact amount consumed and number of demands. Patients experiencing pain were free to receive additional piritramide at any time as rescue medication; however, these patients were withdrawn from the study. Ninety percent of the patients in group A said they were satisfied with or undecided as to the level of analgesia. The corresponding figure in group B was 95 percent. Piritramide consumption was significantly higher in group B than in group A. There were no significant differences between the groups regarding demographic data or duration of surgery, nor did either of these two parameters affect postoperative piritramide consumption. Significant alleviation of pain and improvement in visual analog scale scores from phase I [group A, 4.7 (range, 2.0 to 6.8); group B, 4.6 (range, 3.0 to 8.3)] to phase II [group A, 3.1 (range, 0.4 to 5.2); group B, 3.2 (range, 0.4 to 6.0)] was achieved in both groups. A significant difference in analgesic consumption up to 18 hours postoperatively was seen after dose titration. In the first four hours, the rate of successful demands was significantly higher in group A (80.9 percent) than in group B (40.9 percent). The number of successful demands was comparable in the two groups during phase II (A, 98.8 percent; B, 94.5 percent). In summary, total opioid consumption during the first four hours after operation showed two groups of patients with significantly different needs for piritramide (< 10 mg per 4 hours or > 10 mg per 4 hours). Two different dose regimes were applied using a high and a low bolus size in the following 20 hours. We concluded that effective pain control without respiratory depression was achieved with single-use PCA pumps. Opioid consumption varied significantly, whereas pain levels did not.
