A preliminary study of 24-hour post-cesarean patient controlled analgesia: postoperative pain reports and morphine requests/utilization are greater in abstaining smokers than non-smokers.

Background: Previous clinical studies have not examined the relationship between nicotine abstinence and opioid use for postoperative analgesia. This may be important because tobacco smokers are routinely required to abstain from smoking just before and during acute post-surgical recovery. This study investigated IV morphine self-administration [patient controlled analgesia (PCA)], subjective pain/drug effects and other measures during post-operative (elective Cesarean section) recovery.

Material/methods: Seven females, selected to vary in nicotine use [4 non-using controls (CON), 3 users (NIC)], completed the protocol. Gender, time and type of surgery, and pre- and intra-operative medications were controlled. Subject assessments included the McGill Pain Questionnaire and the Profile of Mood States; drug effects were measured using the Addiction Research Center Inventory.

Results: Mean (M +/-SD) 24-hr morphine responding (button-pressing requests) was significantly higher for NIC (M=183+/-50) than CON (M=38+/-10). Weight-adjusted morphine use (mg/kg/24 hr) was significantly higher for NIC (M=1.80+/-0.23) than CON (M=0.64+/-0.14). Although the groups reported similar pain severity following morphine loading, NIC patients reported significantly greater pain severity than CON patients after 24 hr PCA.

Conclusions: These preliminary data suggest that a history of nicotine use and/or short-term nicotine abstinence can modulate morphine use and analgesia during post-operative recovery. These procedures provide a model for studying patterns and determinants of analgesic self-administration in medical settings.