Predicting postoperative morphine consumption in children

Abstract

Background: Morphine is the most commonly used postoperative analgesic for moderate to severe pain in paediatric patients, but there is little research into predictive factors correlating with postoperative morphine consumption.

Methods: All patients undergoing surgery who received morphine postoperatively over eight months were prospectively enrolled. Data analysed included total morphine consumption to day 3, age, weight, type of surgery, ASA status, preoperative opioid administration, predicted postoperative pain intensity (according to French Society of Anaesthesiology and Intensive Care classification) and surgery duration. Two cohorts were constructed: the first over 6months to construct a statistical model and the second over 2months to validate the model. ANOVA univariate analyses and multivariate linear analysis were performed.

Results: One hundred and fifty-three patients were included in the construct cohort and 40 in the validation cohort. Multivariate analysis demonstrated that total morphine consumption through postoperative day 3 was independently increased by a decreased age, female gender, an increased duration of surgery and an increased morphine titration in PACU. Overall, the model explained 57% of morphine requirement variability. When the model was applied to the validation cohort, a significant correlation was demonstrated between observed and predicted values: r=0.67, P<0.0001.

Conclusion: Age, gender, duration of surgery and doses of titrated morphine in PACU proved to be strong predictors of postoperative morphine consumption by day 3 during paediatric surgery. Knowledge of such factors may help clinicians to better manage postoperative pain in children.

Keywords: Morphine; Paediatric; Pain; Postoperative; Surgery.