Density of spinal anaesthetic solutions.

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 studies 2 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 gran-isetron 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 pro-kinetic 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). 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 …