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Tolerability of acute postoperative pain management
- Jeremy N Cashman, Simon J Dolin (22 January 2007)
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Tolerability of acute postoperative pain management.
- Wolfgang H. Maleck (19 December 2006)
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Standards of care for acute pain management
- James B Sartain (9 November 2005)
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Jeremy N Cashman , Simon J Dolin
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Editor. We would like to thank Dr Maleck for his interest in our article [1] and appreciate his comments. Dr Maleck suggests that it is mathematically impossible and medically unrealistic for the incidence of vomiting in the i.m./s.c. group to be higher than the incidence of nausea, stating that this is seldom the case in real trials. Intuitively this would seem logical. However, there have been a number of studies that have recorded an incidence of vomiting higher than that of nausea, including the large study of 17,201 patients by Forrest and colleagues that we referred to in our discussion. [2] Although we did not use data from Forrest’s study in our analysis four out of the 24 studies of i.m./s.c analgesia that did provide data recorded a higher incidence of vomiting than nausea, [3-6] a further four studies recorded a rate of vomiting equal to that of nausea. However, one of the four studies in which the incidence of vomiting was higher than the incidence of nausea, was a particularly large study that accounted for 2827 patients in the i.m./s.c. group.[3] It is for this reason therefore that the confidence interval in the i.m./s.c. nausea group is so wide and that the mean is so far away from the middle of the confidence interval. In no other group in tables 1 and 2 was there such an effect of a single study. We would concede that this makes the i.m./s.c.data less reliable and reiterate our plea for more studies into the side effects of i.m./s.c analgesia. Finally it is clear from the letters of both Dr Maleck and Dr Anwari [7] that opinion is divided over the contention that PCA opioid administration is more effective than i.m. opioid due to the administration of more opioid which in turn results in a higher incidence of side effects. This obviously warrants further study. 1. Dolin SJ, Cashman JN. Tolerability of acute postoperative pain management: nausea, vomiting, sedation, pruritus and urinary retention. Evidence from published data. Br J Anaesth 2005; 95: 584-91. 2. Forrest JB, Cahalan MK, Rehder K, et al. Multicenter study of general anesthesia. II. Results. Anesthesiology 1990; 72: 262-8. 3. Bonica JJ, Crepps W, Monk B, Bennett B. Postanesthetic nausea, retching and vomiting: evaluation of cyclizine (marezine) suppositories for treatment. Anesthesiology 1958; 19: 532-40. 4. Robinson SL, Fell D. Nausea and vomiting with use of a patient- controlled analgesia system. Anaesthesia 1991; 46: 580-2. 5. Dahl JB, Hjortso NC, Stage J et al. Effects of combined perioperative epidural bupivacaine and morphine, ibuprofen, and incisional bupivacaine on postoperative pain, pulmonary and endocrine-metabolic function after minilaparotomy cholecystectomy. Reg Anesth 1994; 19: 199-205 6. Helmy S. Prophylactic anti-emetic efficacy of ondansetron in laparoscopic cholecystectomy under total intravenous anaesthesia. A randomised, double- blind comparison with droperidol, metoclopramide and placebo. Anaesthesia 1999; 54: 266-71 7. Anwari JS. Standards of care for acute pain management. Br J Anaesth 1006; 96: 665 Conflict of Interest:None declared |
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Wolfgang H. Maleck, Oberarzt Anaesthesie Spital Menziken
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Dear Sir, Dolin and Cashman have written an interesting review which was subject to a letter and reply published in print plus an E-letter.1-3 Although both the letter by Anwari2 and the E-letter by Sartain3 specifically addressed the data on nausea and vomiting contained in tables 1 and 2 of the original review, neither seems to have realised that table 1 contains a figure which is mathematically impossible and medically unrealistic. This is the mean incidence of nausea in the i.m./s.c. group: Dolin and Cashman state it to be 17.0%, but then give a confidence interval of 6.6 - 37.4 %. The mean is usually slightly skewed with respect to the boundaries of the confidence interval (away from 50% in the direction of 0% or 100%), but a mean of 17% is too far away from the middle of the confidence interval which would be 22%. Furthermore, although it is technically possible that the incidence of vomiting is higher than the incidence of nausea, this is seldom the case in real trials and much less in a meta-analysis. Presently, Dolin and Cashman give the incidence of vomiting after i.m./s.c. opioids as 21,9% and the incidence of nause as 17.0%: this is highly improbable, even if the number patients included is somewhat different. In table 1 and 2, for the other two pain control techniques, for nthe mean of all techniques and in the female-only data nausea is always more common than vomiting, as it should be. On the other side, if the mean figure for nausea after i.m./s.c. opioids in table 1 were wrong, than the mean figure for all (male and female) patients in the same table (25.2%) would be wrong, too, as it presently fits the weighted mean of the three groups nicely. Consequently, Dolin and Cashman should re-check their data and publish a correction. If - one year after publication - a comment on the medical message is still allowed I would further like to say that, even if the confidence intervals overlap, I agree with the opinion of Anwari that the superior efficiacy of i.v. PCA is at least in part consequence of more narcotic (plus quicker bioavailability) and hence leads to more opioid-associated complications. For clinical practice, however, I would like to add that in my experience the complications of i.v. PCA can be substantially diminished if the patient is told what drug is in the bag or syringe (i.e. morphine or similar), and that the more often the button is pressed, the more often nausea, drowsiness and pruritus will occur. The patient then makes an informed decision on the balance between pain and side effects based on personal preferences. To my knowledge this has never been investigated, but it would be worthwhile to test: one group is informed that if pain occurs they should simply push the button, the second group is also informed on the nature of side effects, a third group is furthermore told what is in the bag or syringe.One might, of course, argue, that such a study would be unethical or even illegal as, in theory, patients should always be informed on the drugs they receive and the typical side effects. However, in the reality I have seen in different hospitals, patients are often told only "if you have pain, press the button, this will help you! Wolfgang H. Maleck Oberarzt Anaesthesie Spital Menziken Spitalstrasse CH 5737 Menziken Switzerland 1. Dolin SJ, Cashman JN. Tolerability of acute postoperative pain management. Br J Anaesth 2005;95:584-91 2. Anwari JS. Standards of care for PONV. Br J Anaesth 2006;96:665. 3. Sartain JB. Standards of care for acute pain management. E-letter, published 9 November 2005. Conflict of Interest:None declared |
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James B Sartain, Director, Acute Pain Service Cairns Base Hospital, Cairns, Queensland 4870, Australia
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The idea of ‘standards of care’ for side effects of acute pain management is certainly appealing, so Dolin and Cashman deserve credit for their attempt.(1) However, extrapolating from pooled data on publications with different methodology across to Acute Pain Services (APSs) is of questionable validity. For instance, Dolin and Cashman suggest benchmarks for nausea of 25% and vomiting of 20%.(1) A quick glance at the APS papers they discuss highlights the problem very clearly. Koivuranta et al reported a 24-hour incidence of nausea of 52%, whereas one could be forgiven for thinking that Flisberg et al have discovered the Holy Grail of antiemetic prophylaxis, with an incidence of postoperative nausea and vomiting (PONV) of only 3.7% in patients using IV PCA morphine!(2,3) This unrealistic figure contrasts sharply with the results from major prospective trials such as the IMPACT study, which reported far higher levels of PONV even with multiple antiemetics.(4) The problem, of course, lies with variations in the reporting or recording of symptoms. In Koivuranta et al’s study, intended to measure the incidence of PONV, there were structured questionnaires and interviews.(2) In comparison Flisberg et al, whose emphasis was on pain relief and safety, merely “nausea and vomiting reported by the nurse or patient were noted.”(3) In other words, the absence of complaint was taken to indicate the absence of emetic symptoms, almost certainly resulting in vast under-reporting. In order to recommend standards of care, whether for pain control or side effects, some uniformity in the measurement of outcomes is essential. At present in Australia, attempts are being made to develop state-wide or national acute pain databases, usable by multiple institutions, partly in order to establish ‘standards of care’. We have found the devil to be in the detail. Although nearly all hospitals follow the College of Anaesthetists guidelines for assessment and monitoring, precise implementation varies enormously. However, it is clear to all involved that agreement in methodology is essential to avoid gross misinterpretations, as would be possible by comparing the studies cited above. Consequently, it is difficult to see what value can be attached to the recommendations made by Dolin and Cashman.(1) References 1. Dolin SJ and Cashman JN. Tolerability of acute postoperative pain management: nausea, vomiting, sedation, pruritus, and urinary retention. Evidence from published data. Br J Anaesth 2005; 95(5): 584-91. 2. Koivuranta M, Laara E, Snare L, Alahuhta S. A survey of postoperative nausea and vomiting. Anaesthesia 1997; 52: 443-9 3. Flisberg P, Rudin A, Linner R, Lundberg CJF. Pain relief and safety after major surgery. A prospective study of epidural and intravenous analgesia in 2896 patients. Acta Anaesthesiol Scand 2003; 47: 457-65 4. Apfel CC, Korttila K, Abdalla M, Kerger H, Turan A, Vedder I et al. A factorial trial of six interventions for the prevention of postoperative nausea and vomiting. N Eng J Med 2004; 350: 2441-51 Conflict of Interest:None declared |
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