USE OF PATIENT-CONTROLLED ANALGESIA WITH ALFENTANIL FOR EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY

Study Objective: To compare the efficacy of patient-controlled analges ia (PCA) to physician-controlled analgesia in patients undergoing extr acorporeal shock wave lithotripsy (ESWL). Design: Prospective, randomi zed trial. Setting: New Jersey Kidney Stone Treatment Center at Robert Wood Johnson University Hospital, New Brunswick, NJ. Patients: 62 ASA I, II, and III patients undergoing ESWL. Interventions: The control g roup (n = 29) received physician-controlled analgesia with continuous infusions (0.75 mcg/kg/min) and intermittent boluses (5 mcg/kg) of alf entanil. PCA patients (n = 33) initially received alfentanil 0.5 mcg/k g followed by a continuous background infusion (0.2 to 0.5 mcg/kg/min) and self-administered alfentanil (3 to 5 mcg/kg) with a 5-minute lock out period. Bolus doses and infusion rates were determined by patient comfort and cardiorespiratory response to alfentanil. Measurements and Main Results: Prior to the procedure, the patients completed two ques tionnaires (State-Trait Anxiety Inventory and Multidimensional Health Locus of Control Scales). During ESWL, blood pressure, heart rate, res piratory rate, oxygen saturation, end-tidal CO2, and pain and sedation levels were measured at 0, 800, 1,600, 2,400, and 3,000 shock waves. The total doses of alfentanil administered were calculated. PCA patien ts received 31% less alfentanil than control group patients (p < 0.000 1). Patients with more preoperative anxiety required larger doses of a lfentanil (p < 0.05). The pain level was slightly higher in the patien ts receiving PCA (p > 0.05) but most patients reported either no or on ly mild pain. Side effects from the therapy, such as nausea and vomiti ng; were either not present or were mild in both groups, with one pati ent (3% to 4%) in each group reporting mild nausea. Both patients and urologists were very satisfied with the pain management in both groups . Conclusions: PCA is a useful alternative to physician-controlled ana lgesia during ESWL since it provides equivalent pain control while usi ng less alfentanil.