Prediction of outcome: Intrusive and avoidant thoughts about upcoming surgery predict excessive use of postoperative IV patient controlled analgesia

Abstract

Psychosocial factors governing the use of postoperative, intravenous (iv) patient-controlled analgesia (PCA) have received little attention in spite of the fact that PCA is the most common modality for managing pain after surgery. A PCA pump permits patients to self-administer pain medication by pressing a button that triggers delivery of a drug dose. Subsequent button presses do not result in drug delivery until a fixed interval has elapsed. This lockout period is designed to prevent drug overdose. The number of requests for analgesia will exceed the number of drug doses delivered if patients press the button during lockout periods. The motivation behind requests for analgesia during lockout periods is not known. Unrelieved pain and need for additional pain medication are likely reasons but other factors may be involved. To predict postoperative PCA requests during lockout periods based on pre-and postoperative psychosocial factors. 104 women completed measures of mental health and distress one week before major gynecologic surgery by laparotomy. 48 hours after surgery, measures of pain and negative affect were obtained. Cumulative opioid consumption and the time of every button press (drug delivered and not delivered) over the 48 hours were downloaded from the PCA pump. Multiple regression analyses revealed that intrusive and avoidant thoughts (Impact of Events Scale) about the upcoming operation in the weeks preceding surgery, positively predicted (rp = 0.17, p = 0.03) PCA requests during lockout periods, even after controlling for age, preoperative anxiety and depression, and postoperative pain, morphine consumption, and negative affect (R2 for model = 0.34; p < 0.0009). Excessive requests for postoperative PCA during lockout periods appear to reflect, in part, poor preoperative adaptation to surgery involving intrusive thoughts and avoidant response styles. JK is supported by a Canada Research Chair in Health Psychology.