Pain evaluation in patients receiving intravenous patient-controlled analgesia after surgery

To evaluate the effectiveness of intravenous patient-controlled analgesia (PCA) in patients after surgery.

Prospective, observational study.

University teaching hospital.

Sixty patients with American Society of Anesthesiologists physical status I-III receiving intravenous PCA for postoperative pain. The PCA was programmed to deliver morphine 1 mg or hydromorphone 0.1-0.2 mg, with a lockout interval of 10 and 6 minutes for 80% and 20% of the patients, respectively.

Patients were asked, up to 4 times during PCA use and once within 4 hours after PCA use, to describe and rate their intensity of pain at rest and after activity. During the first 12 hours of intravenous PCA use, 75% of the patients reported moderate-to-severe pain > or = 5 on a verbal numeric rating scale) at rest, 80% after activity. Corresponding values, respectively, were 33% and 72% for the 12-24-hour period, 43% and 76% for the 24-36-hour period, and 36% and 64% for the 36-48-hour period of intravenous PCA use. Within 4 hours of stopping PCA, 30% and 58% of the patients had moderate-to-severe pain at rest and after activity, respectively. In approximately 50% of patients, presence of pain was described with words signifying sensory and affective dimensions of pain. Pain control was rated as good or very good by 54% of patients during the first 12 hours of intravenous PCA. Ratings of pain control tended to improve with time.

Successful postoperative pain management using PCA is difficult to achieve on a consistent basis unless treatment is individualized. Our data support the hypothesis that small fixed doses fail to achieve adequate relief in many patients.