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September 1999
Can postoperative nausea and vomiting be predicted?
Sinclair DR, Chung F, Mezei G.
Anesthesiology. 1999 Jul;91(1):109-18.
Commentary by Beverly Philip,
Return to the Current Literature Review Front Page
[ see abstract below ]
Patients with persistent postoperative nausea and vomiting (PONV) in the ambulatory surgical unit have an increased risk of symptoms 24 hours after surgery as well as an approximately 3-to 4-fold increased likelihood of unanticipated admission. However, the routine administration of antiemetics to all patients would result in unnecessary added costs and side-effects. In order to identify which patients might benefit from antiemetic prophylaxis, these authors performed a prospective study in 17,638 consecutive outpatients in order to determine factors predictive of increased risk of PONV.
These ambulatory surgical patients were studied during a 3 year period and consisted of 5,812 men and 11,826 women with a mean age of 47+21 years. Preoperative patient characteristics and intraoperative variables were documented, as well as details of intraoperative and postoperative management. In addition, verbal consent was obtained for a telephone interview 24 hours after operation using a standardized questionnaire.
The overall incidence of PONV before discharge was 4.6%. The incidence of PONV was greater than 6% and unrelated to decade of age in patients 0-50 years, and decreased in the consecutive decades thereafter, to 4.0%, 2.5%, 1.4%, and 0.8%; 40% of patients were over age 50. The incidence in male and female patients was 3.3% and 5.3%, respectively. PONV was more common after general anesthesia than any other technique, and, regardless of anesthetics used, increased with the duration of surgery. There was a wide variation in the incidence of PONV according to the surgical service, and within each service, with the type of procedure done.
Among patients undergoing general anesthesia, those who experienced PONV during the immediate postoperative period had received significantly higher doses of alfentanil, fentanyl and midazolam during their operation. The same was true of patients who underwent monitored anesthesia care. Those who experienced PONV within 24 hours after surgery received significantly higher doses of morphine in the first and second phase of recovery than did those without PONV. The frequency of PONV was also positively related to the degree of excessive postoperative pain.
The 24-hour postoperative telephone interview was completed in 29.8% of patients. The remainder refused to give an interview (33.3%), did not speak English (12.3%), or could not be contacted (23.6%). Among the respondents, 9.1% experienced PONV within 24 hours after operation. 24-hr PONV was more common in patients of female gender (10% versus 7.4% for male patients), patients less than 50 years of age (10.2% versus 6.7% for patients greater than 50 years of age), and in patients with longer durations of anesthesia.
The authors then sought to identify independent predictors of PONV by using a multiple logistic regression with backward stepwise elimination. The predictive factors identified were: age by 10 year intervals (odds ratio 0.87), male gender (0.36), smoking history (0.66), history of previous PONV (3.13), duration of anesthesia by 30 minute increments (1.59), and general versus other anesthesia (10.6). Among surgical services, the incidences were: plastics (odds ratio 6.68), shoulder surgery (5.91), ophthalmologic (5.85), ENT (4.39), non-D&C gynecologic (3.31), orthopedic (2.82), and other orthopedic procedures (2.57).
Knowledge of these predictors of PONV should aid anesthesiologists� efforts to reduce the incidence of PONV by selecting appropriate patients for antiemetic therapy. This may lead to improved, cost-effective use of available drugs and resources.
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Front Page , or read the abstract:
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ABSTRACT
BACKGROUND: Iletrospective studies fail
to identify predictors of postoperative nausea and vomiting (PONV).
The authors prospectively studied 17,638 consecutive outpatients who
had surgery to identify predictors.
METHODS: Data on medical conditions, anesthesia,
surgery, and PONV were collected in the post-anesthesia care unit, in
the ambulatory surgical unit, and in telephone interviews conducted
24 h after surgery. Multiple logistic regression with backward stepwise
elimination was used to develop a predictive model An independent set
of patients was used to validate the model
RESULTS: Age (younger or older), sex (female
or male), smoking status (nonsmokers or smokers), previous PONV, type
of anesthesia (general or other), duration of anesthesia (longer or
shorter), and type of surgery (plastic, orthopedic shoulder, or other)
were independent predictors of PONV. A 10-yr increase in age decreased
the likelihood of PONV by 13%. The risk for men was one third that for
women. A 30-min increase in the duration of anesthesia increased the
likelihood of PONV by 59%. General anesthesia increased the likelihood
of PONV 11 times compared with other types of anesthesia. Patients with
plastic and orthopedic shoulder surgery had a sixfold increase in the
risk for PONV. The model predicted PONV accurately and yielded an area
under the receiver operating characteristic curve of 0.785+/-0.011 using
an independent validation set.
CONCLUSIONS: A validated mathematical
model is provided to calculate the risk of PONV in outpatients having
surgery. Knowing the factors that predict PONV will help anesthesiologists
determine which patients will need antiemetic therapy.
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