CONTEXT: Physicians frequently prescribe respiratory treatments to hospitalized patients, but the influence of such treatments on clinical outcomes is difficult to assess. OBJECTIVE: To compare the clinical outcomes of patients receiving respiratory treatments managed by respiratory care practitioner (RCP)-directed treatment protocols or physician-directed orders. DESIGN: A single center, quasi-randomized, clinical study. SETTING: Three internal medicine firms from an urban teaching hospital. PATIENTS: Six hundred ninety-four consecutive hospitalized non-ICU patients ordered to receive respiratory treatments. Main outcome measures: Discordant respiratory care orders, respiratory care charges, hospital length of stay, and patient-specific complications. Discordant orders were defined as written orders for respiratory treatments that were not clinically indicated as well as orders omitting treatments that were clinically indicated according to protocol-based treatment algorithms. RESULTS: Firm A patients (n = 239) received RCP-directed treatments and had a statistically lower rate of discordant respiratory care orders (24.3%) as compared with patients receiving physician-directed treatments in firms B (n = 205; 58.5%) and C (n = 250; 56.8%; p < 0.001). No statistically significant differences in patient complications were observed. The average number of respiratory treatments and respiratory care charges were statistically less for firm A patients (10.7 +/- 13.7 treatments; $868 +/- 1,519) as compared with patients in firms B (12.4 +/- 12.7 treatments, $1,124 +/- 1,339) and C (12.3 +/- 13.4 treatments, $1, 054 +/- 1,346; p = 0.009 [treatments] and p < 0.001 [respiratory care charges]). CONCLUSIONS: Respiratory care managed by RCP-directed treatment protocols for non-ICU patients is safe and showed greater agreement with institutional treatment algorithms as compared with physician-directed respiratory care. Additionally, the overall utilization of respiratory treatments was significantly less among patients receiving RCP-directed respiratory care.