© The Board of Management and Trustees of the British Journal of Anaesthesia 2004
CORRESPONDENCE |
Nausea and vomiting after fast-track cardiac anaesthesia
Editor—We read with interest the paper by Kogan and colleagues1 looking at the incidence and risk factors for postoperative nausea and vomiting (PONV) after fast-track cardiac anaesthesia (FTCA). We would first like to congratulate the authors on producing a study with such high numbers and second to comment on several points.First, we have performed a prospective audit of PONV in 106 consecutive patients undergoing ‘on-pump’ cardiac surgery. Postoperative sedation was with low-dose propofol infusion and nurse-controlled morphine infusion as opposed to bolus midazolam and morphine. Although not all patients were suitable for FTCA, the mean duration of ventilation was comparable in the two groups (11.0 h after standard cardiac anaesthesia vs 8.1 h in the fast-track patients). Nausea was reported in 11/106 (10.4%) and vomiting occurred in 16/106 patients (15.1%). Whilst our overall incidence of PONV was remarkably similar to Kogan's (25.5% vs 24%, respectively), a greater percentage of those with postoperative nausea actually vomited in our study. Kogan postulated that this PONV might be caused by the small doses of morphine given after surgery. However, our data show no difference in the incidence of PONV in patients who received more or less than a total dose of morphine 15 mg.
We suspect that a possible explanation may be the routine use of a nasogastric tube by Kogan.1 This deflates the stomach that may have been distended by gas swallowed by the patient as they wake up, or insufflated during bag and mask ventilation at induction of anaesthesia. Currently, it is not standard practice in our institution to use nasogastric tubes and we will look into this further.
Second, we were surprised by the choice of metoclopramide as a first line antiemetic. Numerous studies2 have shown it to be inferior to other antiemetics when used in the context of PONV. However, the figures from Kogan's study suggest that second-line rescue medication (ondansetron) was only needed in 3.1% of cases. This implies metoclopramide is effective at the relatively small dose of 10 mg. We believe that our current practice of using granisetron as a first-line antiemetic is evidence-based.3 However, as mentioned above, our figures, showing a higher proportion of those with nausea going on to vomit, do not support this. Could this efficacy be attributable to metoclopramide's gastric prokinetic effects?
Thirdly, we would like to reassure Kogan and colleagues that in our audit (that also looked at chest drain losses), we did not find a relationship between an increased chest drain loss and PONV (763 ml in patients with no PONV vs 773 ml in patients who had PONV).
London, UK
Editor—In reply to Dr Morton's letter, referring to our article in the BJA,1 I would firstly like to point out the interesting similarity in the results from our department and their own on the prevalence of PONV after fast-track cardiac anaesthesia. The use of opioids in the postoperative period is one of the main risk factors for PONV,4 and reducing the dose of morphine might decrease its incidence. The routine use of a nasogastric tube may also reduce the occurrence of postoperative vomiting (but not nausea).5 Secondly, metoclopramide has been used for many years as an antiemetic. It is inexpensive and, in the study of Woodward and colleagues,6 proved to be more effective than ondansetron for PONV prevention after cardiac surgery.
Tel Aviv, Israel
References
1 Kogan A, Eidelman LA, Raanani E, et al. Nausea and vomiting after fast-track cardiac anaesthesia. Br J Anaesth 2003; 91: 214–17
2 Henzi J, Walder B, Tramèr MR. Metoclopramide in the prevention of postoperative nausea and vomiting: a quantitative systematic review of randomized placebo-controlled studies. Br J Anaesth 1999; 83: 761–71
3 Gan TJ, Meyer TMS, Apfel CC, et al. Consensus guidelines for managing postoperative nausea and vomiting. Anesth Analg 2003; 97: 62–71
4 Gan JG. Postoperative nausea and vomiting—can it be eliminated? JAMA 2002; 287: 1233–6
5 Cheatham ML, Chapman WC, Key SP, Sawyers JL. A meta-analysis of selective versus routine nasogastric decompression after elective laparotomy. Ann Surg 1995; 221: 469–76[Web of Science][Medline]
6 Woodward DK, Sherry KM, Harrison D. Antiemetic prophylaxis in cardiac surgery: comparison of metoclopramide and ondansetron. Br J Anaesth 1999; 83: 933–5
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