| Postoperative Pain Control with Thoracic Eidural Block. |
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Duck Mi Yoon, Young Sook Kim, Jong Rae Kim, Kwang Won Park |
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Department of Anesthesiology, Yonsei University School of Medicine, Seoul, Korea. |
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| Abstract |
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It is well known that a significant decrease in ventilatory function and arterial oxygenation follows upper abdominal surgery (Bromage, 1967; Bridenbaugh et al., 1972). In the first few hours after operation, hypoxemia is thought to be due to regional misalignment of ventilation and perfusion (Nunn and Payne, 1962). Diament and Palmer (1966) have shown that, by the end of 24 hours, frank shunting of blood past collapsed alveoli is the dominant factor (Georg et al., 1967) Pain arising from the upper abdomir,al regions can result in shallow breathing, diminished cough ability, retained bronchial secretions and eventually atelectasis (Bendixen et al., 1964). Narcotic drugs are most frequently used in postoperative pain control, but too large or too frequent doses may result in hypoventilation and subsquent atelectasis (Yakaitis et al., 1972). Epidural block has been advocated for pain control after upper abdominal surgery, because pain can be abolished completely (Bonica, 1953), arterial oxygenation improved (Spence and Smith, 1971) and the frequency of respiratory complications reduced (Wahba et al., 1975). Twenty eight patients for upper abdominal surgery, chosen at random, were studied for postoperative pain relief. In ten patients pain was managed by meperidine and in the other eighteen patients it was managed by tboracic epidural block with 0. 25% bupivacaine. In both groups, pulmonary funtions were assessed by measurement of arterial blood gases, tidal volume, respiratory rate, minute volume, vital capacity, timed vital capacity and peak flow, and by calculation of A-aDO2 These measurements were assessed before operation, on the first postoperative day, the second day and the fifth day. The effect on pain relief, of epidural analgesia after upper abdominal surgery and the patients ability to cough, to take deep breaths and to sit up were assessed objectively by the same physician and subjectively by each patients. The results of this study were summarized as follows: 1) Minute volume showed no significant change in both groups. Increase in respiration rate and decrease in tidal volume of the control group in postoperative days 1 and 2 were significant when compared with preoperative values, but changes in the epidural group were noticed in postoperative day l. 2) Peak flow, FEV, and FVC of both groups were significantly reduced in postoperative days 1 and 2, but in the 5th day peak flow values of the epidural group were restored to postoperative levels. There was no significant change between the groups.
3) Differences between decreased PaO2 and increasedA-aDO, of the control group in post- operative days 1 and 2 were significant when compared with preoperative values, but changes in the epidural group were not significant. The values of PaCOpH and BE were not significantly changed. 4) The epidural analgesic effect was excellent in postoperative pain control, and resulted in much improvement in the patients ability to cough, breathe deeply and to sit up.
From the results described above, epidural analgesia is a reliable method of controlling pain after upper abdominal operations, especially in aged or debilitated patients with ventilatory dysfuntion. |
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