PURPOSE: The aim of this study was to test the effectiveness of a quality improvement postoperative pain treatment program after cardiac surgery. MATERIALS AND METHODS: This was a prospective, quasiexperimental study using nonequivalent groups comprising 3 periods: baseline (group baseline), implementation of the algorithm for acute pain management, and reassessment (group reassessment). Inclusion of 133 patients after elective cardiac surgery at an 18-bed surgical intensive care unit (SICU) at a Swiss university hospital. The algorithm was implemented by training, pocket guidelines, regular audits, and feedback. The implementation period was completed when the adherence to 2 of 3 process indicators attained at least 70% over 2 months. Visual analog scales (VAS) for pain, morphine consumption, pain perception, and sleep quality were assessed during stay in SICU and after 1 month and 6 months. RESULTS: The assessment included 79 patients at baseline and 54 in the reassessment periods. Pain intensity at rest decreased from 2.7 +/- 1.4 to 2.2 +/- 1.4 cm (VAS; P =.008). Retrospective perception of pain intensity at rest decreased from 3.8 +/- 2.2 to 2.6 +/- 1.8 (P =.004). The proportion of patients with no pain or often without pain increased from 11% to 37% (P =.005). The number of patients with sleep disturbances decreased from 68% to 35% (P =.012). No differences were observed at 1 and 6 months postoperatively. CONCLUSIONS: After algorithm implementation in the SICU, pain intensity at rest decreased and quality of sleep improved.