[Influence of postoperative pain therapy on nausea and vomiting]

Postoperative nausea and vomiting remains an important problem. Many risk factors have been identified; however, the importance of postoperative analgesic technique and patient expectation remain poorly defined.

We prospectively collected data on postoperative nausea and vomiting (PONV) in four groups of randomly selected patients (n=50 per group) who received either simple analgesics, nurse-administered intravenous morphine (NAA), patient-controlled analgesia (PCA) with morphine or epidural analgesia with bupivacaine and fentanyl. Patients were questioned regarding any past history of PONV or motion sickness, their preoperative expectation of suffering PONV and satisfaction with their antiemetic therapy.

The incidence of nausea was higher in both morphine groups P<0.05), women (P<0.05), those less than the median age of their group (P<0.05) and those with a past history of PONV (P<0.05) or motion sickness (P<0.05). Most patients did not expect to experience PONV (19.3%). The incidence of nausea was higher in those expecting to experience PONV than in those not expecting to suffer PONV (P<0.01). Of those who received postoperative antiemetic treatment, 23.6% were dissatisfied or very dissatisfied with their therapy. Few patients received a prophylactic antiemetic drug (15%).

Study results show that patient expectation is a potent predictor of postoperative nausea, a risk factor hitherto ignored in the anaesthetic literature, and that, in the provision of analgesia following major surgery, epidural analgesia is associated with less PONV than intravenous morphine.