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© 1999 International Anesthesia Research Society
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Abstract |
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The efficacy of pleural analgesia after nephrectomy is controversial. We therefore evaluated IV opioid requirements in patients with and without pleural bupivacaine. Patients undergoing elective nephrectomy were randomly assigned to receive postoperative IV piritramid alone (n = 18) or piritramid combined with pleural bupivacaine (n = 19). In the patients assigned to receive pleural analgesia, boluses of 20 mL of 0.25% bupivacaine were given at 6-h intervals via an pleural catheter that was inserted in the medial axillary line at the sixth intercostal space. Pain scores (10-cm visual analog scale) and opioid requirements were recorded over the first 2 postoperative days. One hour after pleural puncture, a chest radiograph was performed. The catheter was removed 48 h after insertion. Patient characteristics were similar in each group, as was the duration of surgery. Pain scores were similar in each group: 3.0 ± 2.5 in those given pleural bupivacaine and 3.1 ± 2.7 in those given piritramid alone. However, the piritramid requirement was significantly less in those given pleural bupivacaine (23 ± 3 mg) than in those given piritramid alone (45 ± 6 mg). Furthermore, the time from completion of surgery until the first opioid request was significantly longer in the patients who received bupivacaine (4.7 ± 1.0 vs 2.8 ± 1.0 h). One patient had a small pneumothorax that resolved without treatment. These data indicate that pleural analgesia is effective and provides a significant opioid-sparing effect.
Implications: We conclude that pleural analgesia significantly prolongs the time until postoperative opioid was first requested and halves the total required dose. These data indicate that pleural analgesia is effective and provides a significant opioid-sparing effect.
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Introduction |
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Since its first description (1), pleural analgesia has proven a safe and effective treatment (2,3) for pain resulting from laparoscopic cholecystectomy (4), open cholecystectomy (5), multiple fractured ribs (6), blunt thoracic trauma (7), herpes zoster (8), and pancreatic tumors (9). The technique seems less reliable for thoracotomy, having been variously reported as providing adequate (10) or inadequate (11) pain relief.
Despite the large positive experience with pleural analgesia after cholecystectomy (12,13), only a few studies have evaluated the method for treatment of nephrectomy pain (14–16). Furthermore, the results have been mixed (3,17). Variable efficacy reported in the literature (14,15,17) contrasts with our excellent clinical experience with the technique.
Baude et al. (15) compared epidural opioids with pleural bupivacaine and with IV opioids. Pleural analgesia was found to be ineffective, with visual analog scale (VAS) scores >5. Murphy (14) reported inadequate analgesia in four of eight patients after nephrectomy. He "felt that the posterior extension of the operation scar might have contributed to inadequacy of the block" and that inserted drainage tubes may also have contributed.
We therefore tested the efficacy of 20 ml of pleural bupivacaine 0.25%, administered at 6-h intervals the first 48 h after nephrectomy. No drainage tubes were placed. Efficacy was defined by a VAS score and the extent to which pleural analgesia reduced the need for IV opioids.
There is no consensus about the terminology used to designate pleural analgesia (3,18,19). When the method was first used, it was described as "interpleural" analgesia. However, "parietal and visceral pleura are continuous around the hilar structures and the right and left pleura sacs are distinct. Therefore, an injection of a local anesthetic through a needle that has penetrated the parietal membrane, but not the visceral membrane, is ‘intrapleural’ analgesia" (18). The accumulation of fluid within the pleural space is also called pleura effusion. The epidural space is also a potential space. We do not use "interepidural analgesia" or an "intradural catheter." As Baumgarten (19) suggested, the best solution to this controversy would be to abandon the two prefixes and to call the technique "pleural block" or "pleural analgesia."
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Methods |
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After approval by the local ethics committee and written informed consent, we enrolled 40 patients scheduled for elective nephrectomy. The inclusion criteria were age 19–75 yr, ASA physical status I–III, and no contraindication to any study drugs.
The patients were premedicated with ranitidine and oxazepam the evening before and 7 AM on the day of surgery. Anesthesia was induced with propofol (1.5–2.5 mg/kg) and fentanyl. Endotracheal intubation was facilitated by the administration of vecuronium. Anesthesia was maintained with isoflurane in a nitrous oxide/oxygen mixture. Before emergence from anesthesia, the neuromuscular blockade was antagonized by the IV administration of atropine and neostigmine.
At the end of surgery, patients were randomly assigned to two treatment groups based on computer-generated codes: 1) pleural analgesia combined with the IV administration of the opioid piritramid and 2) IV piritramid alone. In patients assigned to pleural analgesia, an pleural catheter was positioned at the sixth intercostal space in the midaxillary line with the patient in the supine position just before anesthesia was discontinued during spontaneous ventilation.
The pleural catheter was inserted, as previously described (20), via a 16-gauge Tuohy needle connected to a Y-piece. Briefly, one arm of the Y-piece was connected to a balloon, which collapsed when the needle was introduced into the negative intrathoracic pressure of the pleural cavity. The catheter (0.6 x 1.0 mm diameter; Pleurocert®; Fa. B. Braun Melsungen, Melsungen, Germany) was then inserted through the other arm of the Y-piece to a distance of 5 cm. This closed system minimizes the likelihood of pneumothorax. The first 20-mL bolus of bupivacaine 0.25% was given immediately after catheter insertion. Patients were subsequently given 20 mL of pleural bupivacaine 0.25% every 6 h until the second postoperative day. The catheter was removed approximately 48 h after insertion.
In both groups, pain was treated with IV piritramid, a pure µ receptor agonist. One milligram of the synthetic opioid piritramid is equipotent to 0.8 mg of morphine hydrochloride (21). Every 6 h, pain was recorded by using the VAS, and patients were asked whether they needed pain relief medication. Opioids were given in the range of 7.5–15 mg at any time by the nurses on patient demand, but not more often than at 6-h intervals.
A preoperative chest radiograph was obtained per clinical routine; 1 h after pleural puncture, a chest radiograph was obtained for detection of a possible pneumothorax. Pain was evaluated at 6-h intervals with a 10-cm VAS (0 = no pain and 10 = excruciating pain). The times until pain medication was first requested and total opioid requirement during the first 2 postoperative days were recorded.
Potentially confounding variables and total opioid dose were evaluated by using two-tailed, unpaired t-tests. The times until pain medication was first requested in each group were compared by using a Mann-Whitney U-test. Pain scores over time were compared by using a one-way analysis of variance. Data are presented as means ± SD. P < 0.05 was considered statistically significant.
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Results |
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Two patients (one in each group) were withdrawn from the study after unplanned transfers to the intensive care unit (ICU). The patient randomized to the catheter group had a coagulation disorder and experienced massive bleeding intraoperatively. She was transferred to the ICU without a catheter. The patient in the control group had an acute myocardial ischemia 2 days after surgery and died 1 day later in the ICU. An additional patient in the control group withdrew. We thus had a total of 18 patients available for analysis in the piritramid alone group and 19 patients in the pleural analgesia group.
Patient characteristics were comparable in the two study groups (Table 1), as was the duration of surgery (2.8 ± 1.0 h in the pleural catheter group versus 2.9 ± 0.6 h in the IV opioid group) and intraoperative fentanyl use (0.6 ± 0.3 vs 0.6 ± 0.2 mg). VAS scores for pain were relatively low and were comparable in each group (Fig. 1).
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). Data are presented as mean ± SD.An opioid was first requested significantly later in the patients given pleural analgesia (4.7 ± 1.0 h) versus piritramid alone (2.8 ± 1.0 h). Furthermore, only about half as much opioid was required on the first and second postoperative days in the patients given pleural analgesia (Table 2).
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Catheter insertion using the balloon method described above proved facile, and it was easy to identify the pleural space. One patient had a definite, and another a possible, small pneumothorax, but neither had symptoms, and after radiograph were both normal. In both cases, the pleura had been opened by the surgeons intraoperatively, then closed without placement of a chest tube. Neither patient required treatment. All other chest radiographs were unchanged from the preoperative radiographs. No patients experienced symptoms of local anesthetic toxicity.
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Discussion |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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Since the initial report of pleural local anesthetics administration by Reiestad and Stromskag (1), there have been mixed results of their efficacy for pain relief after nephrectomy. Some studies after cholecystectomy included few nephrectomy patients with poor results (1,17,22); others compared epidural opioids with pleural local anesthetics (15). We investigated the use of pleural bupivacaine for pain relief after nephrectomy.
The mechanism of action of local anesthetics injected between the parietal and visceral pleura is understood as retrograde diffusion to reach the intercostal nerves, the splanchnic nerves, and the sympathetic chain, which are adjacent to the parietal pleura. Using computed tomography, Stromskag et al. (23) found gravity-dependent intercostal nerve blockade. With patients in the supine position, these authors found analgesia from T5 to L1, and the paravertebral area was covered by local anesthetic solution. In the paravertebral area, the sympathetic chain and the splanchnic nerves are separated from the pleura cavity only by the parietal pleura. Similar results were described by van Kleef et al. (22). Five and a half dermatomes were blocked for approximately 8 h using bupivacaine 0.25% pleurally after cholecystectomy.
Pain scores of patients given pleural analgesia supplemented with piritramid were similar to those of patients given piritramid alone. Furthermore, the scores were relatively low in each case. Thus, our major finding is that pleural analgesia significantly prolonged the time until postoperative opioid was first requested and decreased the total required dose by a factor of 2. These data indicate that pleural analgesia is effective and provides a substantial opioid-sparing effect.
As previously reported, sufficient postoperative analgesia improves lung function by facilitating early patient mobilization. Early mobilization also reduces atelectasis in basal and dorsal lung compartments. However, opioid administration is associated with postoperative hypoventilation. As might be expected, pleural analgesia improves pulmonary function and postoperative oxygenation compared with IV opioids (13,24).
Pleural analgesia is associated with a number of potential complications, most notably pneumothorax and local anesthetic toxicity (2,3,25). IV opioids are similarly associated with risks, especially ventilatory depression and cognitive impairment that may restrict early postoperative ambulation. We did not observe any substantial complications in either group. However, too few patients were included in our protocol to evaluate the relatively uncommon adverse effects associated with either method.
Plasma concentrations of bupivacaine during pleural analgesia have been evaluated in numerous previous studies (5,12,22). The estimated threshold plasma concentration associated with the onset of central nervous system toxicity for bupivacaine is thought to be 2–4 µg/mL (3). We chose 20 mL of pleural bupivacaine 0.25% every six hours because this dose is unlikely to be associated with toxic plasma concentrations (3). van Kleef et al. (22) also found no difference between the use of 0.5% and 0.25% bupivacaine after cholecystectomy. They found a slightly lower VAS score for pain (approximately 2) but a higher opioid requirement in both groups (29 mg in the first 24 hours) than we found in the local anesthetic group.
In contrast to previous reports (14,15), we showed in our investigation that using a timed regimen of pleural local anesthetic is effective after nephrectomy. Frenette et al. (24) reported a improvement of lung function using pleural analgesia, and an additional reduction in stress response and catecholamine release, resulting in an early normalization of postoperative bowel function, was found by Kastrissios et al. (13).
The risk of pneumothorax is reduced when the recommended technique of insertion of the catheter is used (2). Although high plasma local anesthetic concentrations are attained with pleural analgesia, clinical toxicity is rarely reported (3,25). Little correlation was found between plasma bupivacaine concentration and central nervous system toxicity. The rate of change in plasma concentration seems to be more important in determining clinical toxicity than the absolute plasma bupivacaine concentration (3,25).
In summary, 20 mL of pleural bupivacaine 0.25% every six hours provided a substantial opioid-sparing effect during recovery from nephrectomy and extended the time until opioids were needed for pain relief. This indicates that the technique is effective and reduces the need for postoperative opioids with their associated potential complications
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Acknowledgments |
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Supported by Astra Austria, Inc., Linz, Austria.
We gratefully acknowledge the support and generous assistance of Daniel I. Sessler, MD, Department of Anesthesia and Perioperative Care, University of California-San Francisco.
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References |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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- Reiestad F, Stromskag K. Interpleural catheter in the management of postoperative pain: a preliminary report. Reg Anesth 1986;11:89–91.
- Stromskag KE, Minor B, Steen PA. Side effects and complications related to interpleural analgesia: an update. Acta Anaesthesiol Scand 1990;34:473–7.[Web of Science][Medline]
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Murphy DF. Interpleural analgesia [see comments]. Br J Anaesth 1993;71:426–34.
[Free Full Text] - Schulte-Steinberg H, Weninger E, Jokisch D, et al. Intraperitoneal versus interpleural morphine or bupivacaine for pain after laparoscopic cholecystectomy. Anesthesiology 1995;82:634–40.[Web of Science][Medline]
- Rose U, Attar Z. Intrapleural bupivacaine and parenteral opioid for postoperative analgesia: a comparative study. Anaesthesist 1992;41:53–7.[Web of Science][Medline]
- Wulf H, Jeckstrom W, Maier C, et al. Intrapleural catheter analgesia in patients with multiple rib fractures. Anaesthesist 1991;40:19–24.[Web of Science][Medline]
- Knottenbelt JD, James MF, Bloomfield M. Intrapleural bupivacaine analgesia in chest trauma: a randomized double-blind controlled trial. Injury 1991;22:114–6.[Web of Science][Medline]
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- Myers DP, Lema MJ, de Leon-Casasola OA, et al. Interpleural analgesia for the treatment of severe cancer pain in terminally ill patients. J Pain Symptom Manage 1993;8:505–10.[Web of Science][Medline]
- Mann LJ, Young GR, Williams JK, et al. Intrapleural bupivacaine in the control of postthoracotomy pain. Ann Thorac Surg 1992;53:449–54.[Abstract]
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Schneider RF, Villamena PC, Harvey J, et al. Lack of efficacy of intrapleural bupivacaine for postoperative analgesia following thoracotomy. Chest 1993;103:414–6.
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Stromskag KE, Reiestad F, Holmqvist EL, et al. Intrapleural administration of 0.25%, 0.375%, and 0.5% bupivacaine with epinephrine after cholecystectomy. Anesth Analg 1988;67:430–4.
[Abstract/Free Full Text] - Kastrissios H, Mogg GA, Triggs EJ, et al. Interpleural bupivacaine infusion compared with intravenous pethidine infusion after cholecystectomy. Anaesth Intensive Care 1991;19:539–45.[Web of Science][Medline]
- Murphy DF. Intercostal nerve blockade for fractured ribs and postoperative analgesia: description of a new technique. Reg Anesth 1983;8:151–3.
- Baude C, Long D, Chabrol B, et al. Postoperative analgesia for nephrectomy. Cah Anesthesiol 1991;39:533–6.[Medline]
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- Miguel R, Smith R. Intrapleural, not interpleural, analgesia [letter]. Anesth 1991;16:299.
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van Kleef JW, Logeman EA, Burm AG, et al. Continuous interpleural infusion of bupivacaine for postoperative analgesia after surgery with flank incisions: a double-blind comparison of 0.25% and 0.5% solutions. Anesth Analg 1992;75:268–74.
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- Frenette L, Boudreault D, Guay J. Interpleural analgesia improves pulmonary function after cholecystectomy. Can J Anaesth 1991;38:71–4.[Web of Science][Medline]
- Kreitzer JM, Reuben SS. Central nervous system toxicity in a patient receiving continuous intrapleural bupivacaine. J Clin Anesth 1996;8:666–8.[Web of Science][Medline]
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