Postoperative pain management and respiratory depression after thoracotomy: a comparison of intramuscular piritramide and intravenous patient-controlled analgesia using fentanyl or buprenorphine.

STUDY OBJECTIVE

To compare the analgesic efficacy of fentanyl, buprenorphine, and piritramide and to define the respiratory risk during conventional postoperative pain management and patient-controlled analgesia (PCA).

DESIGN

Randomized, single-blind study.

SETTING

Department of anesthesiology of an urban hospital.

PATIENTS

Sixty patients (ASA) physical status II and III) recovering from unilateral thoracotomy performed under standardized general anesthesia including intercostal blockade.

INTERVENTIONS

Patients were treated with intramuscular (IM) piritramide (7.5 to 15 mg as needed) or intravenous (IV) PCA with fentanyl (demand dose 34 micrograms) or buprenorphine (demand dose 80 micrograms) during the early postoperative period, using the On-Demand Analgesia Computer (ODAC, Janssen Scientific Instruments, Beerse, Belgium).

MEASUREMENTS AND MAIN RESULTS

The mean postoperative observation period was 24 to 25 hours. During this time, patients requested 55.8 +/- 23.2 mg of piritramide, 1.04 +/- 0.54 mg of fentanyl, or 1.81 +/- 0.78 mg of buprenorphine. Analgesia in all groups was judged mostly good to excellent, with a preference for PCA. Side effects were only of minor intensity in all groups; euphoria or dysphoria occurred only with buprenorphine. Two patients using PCA and five patients having IM analgesia developed short periods of respiratory depression (respiratory rate less than or equal to 8 breaths/minute and/or oxygen (O2) desaturation less than or equal to 90%), which promptly responded to commands to breathe deeply. Respiration rates did not differ, and frequent arterial blood sampling showed normal mean partial pressures of oxygen (PO2) and carbon dioxide (PCO2) and arterial oxygen saturation (SaO2) in all subgroups.

CONCLUSIONS

Opioid-induced respiratory depression occurred infrequently during postoperative pain management whether by conventional means or using PCA, even though high doses of opioid analgesics were required intermittently for adequate postoperative pain relief by either technique.