Incidence of nausea and vomiting after hysterectomy
Postoperative nausea and vomiting (PONV) is a relatively common, troublesome, and potentially hazardous complication of surgery. Its incidence in the general surgical population has been estimated to be between 8–92% although most estimates are around 20–30%. Despite the wide variety of available antiemetic medications, current treatment of PONV is considered to be poor. It is thought that in the patient-controlled analgesia (PCA) environment, nausea and vomiting may limit patients’ use of opioid analgesics; patients may in fact use PCA to balance pain against side-effects such as nausea.
Clearly, minimising PONV is an important clinical goal and most strategies to alleviate it have revolved around the use of antiemetic medication, especially in patients receiving opioid analgesics for postoperative pain management. It has long been speculated that rapid changes in blood opioid concentration are more likely to cause unpleasant side-effects than more gradual changes in concentration but simple manoeuvres to alleviate PONV, such as altering the mode of analgesic drug administration, appear not to have been investigated. Some devices used for PCA allow the duration over which a dose is delivered to be either ‘bolus’ (usually delivered over around 40 s) or over a longer period, typically 5 min. Increasing the bolus dose delivery duration time will decrease the rate of change of blood drug concentration and the maximum blood-drug concentration (Cmax ) whilst prolonging the time to Cmax (tmax ). This study was performed to test the hypothesis that increasing the duration of delivery of morphine would decrease the incidence of PONV.
This work was presented as a poster at the 11th World Congress of Anaesthesiologists, Sydney April 17, 1996.
Forty-eight patients aged between 34 and 74 years (mean age 47 years; s.d.=8) undergoing total abdominal hysterectomies were selected for the study. All patients approached agreed to participate. All patients had similar systemic pathology (ASA 1–2) and had renal and liver functioning within normal physiological limits. Patients who could not understand the English language or the concept of PCA, those with a history of mental illness and those receiving monoamine oxidase inhibitors (MAOI) within 14 days prior to the study were excluded from selection. Four patients were withdrawn from the study: one patient was not using PCA because she had very little pain, one patient disliked morphine and requested pethidine, one patient underwent a vaginal rather than abdominal hysterectomy, and one patient underwent a laparotomy. Two patients received intra- or post-operative ketorolac, a third patient received ondansetron and another patient had insufficient data recordings taken. These patients were not included in the statistical analysis.
Filed under: Clinical Pharmacology