CLONIDINE VS PIRITRAMIDE FOR PATIENT-CONT ROLLED ANALGESIA

Following parenteral administration, clonidine has analgesic effects a t both cerebral and spinal levels. Patient-controlled analgesia (PCA) makes it possible to determine equipotent dosages of analgesics by rel ating analgesic consumption per time to the levels of analgesia obtain ed in comparable patient populations. Therefore, we studied the equipo tency ratios of clonidine and piritramide and the incidence of undesir ed side effects in the treatment of postoperative pain in patients und ergoing maxillo-facial surgery. Methods. After approval of the local e thics committee and informed consent 40 patients (age > 18 year, ASA I -III) were studied. Following randomization, the patients each receive d a PCA device containing either clonidine (bolus 30 mu g), or piritra mide (bolus 1.5 mg) for treatment of postoperative pain (lockout inter val 5 min in both groups). During the postoperative period, pain was d etermined using a visual ana logue scale, while analgesic consumption, sedation, haemodynamic parameters, respiration rate, and the occurren ce of undesired side effects were documented additionally. Results. Th e groups had comparable distributions of biometric data, duration of a naesthesia, and ASA classification. Pain level decreased significantly (P<0.0001) in both groups during the first 2 h of PCA. Mean arterial pressure and heart rate were lower (P<0.05) in the clonidine group 4 a nd 6 h after PCA onset, while the degree of sedation after 2 (P<0.01) and 6 (P<0.05) h was higher than in the piritramide group. Nausea and vomiting were more frequent (P<0.05) in the piritramide group. Both gr oups showed a wide interpatient variation in anal gesic requirement: T he equipotency ratio clonidine/piritramid was 1:63.7.Conclusions. Intr avenous clonidine is a potent analgesic and is suitable or the treatme nt of postoperative pain following maxillo-facial surgery. The analges ic potency of 150 mu g clonidine i.v. was equivalent to that of 9.56 m g piritramide i.v. Nausea and vomiting occurred more rarely in the clo nidine group, while deeper was observed more frequently than in the pi ritramide group. Owing to the wide interindividual variation of analge sic consumption, clonidine dosages have to be adjusted to the actual r equirements.