BACKGROUND: Patients undergoing mechanical ventilation in the ICU often receive supplemental oxygen. If not closely monitored, this may lead to hyperoxia. The use of an oxygen-weaning protocol may reduce this risk by pacing the titration of oxygen therapy to patient needs. ICU protocols are correlated with decreased mortality and length of stay and have great potential for cost savings. The goals of this study were to determine whether the oxygen-weaning protocol at a university-affiliated hospital was followed and to measure the length of time respiratory therapists took to wean patients once the oxygen-weaning parameters were met. METHODS: This was a retrospective chart review of subjects > 18 y of age admitted to the medical ICU who underwent intubation and mechanical ventilation and were placed on an oxygen therapy protocol. The following data were collected: demographics, arterial blood gases, the length of time to change F IO 2 after meeting weaning parameters, and the percent change in F IO 2. RESULTS: Data were collected from 30 subjects. The most common oxygen saturation parameter measured via pulse oximetry (S pO 2) used to initiate weaning oxygen was 92%. The mean 6 SD F IO 2 administered to subjects was 39.6 6 15.3% prior to extubation. The majority of subjects exhibited adequate oxygenation prior to extubation (mean 6 SD): P aO 2 99.3 6 6.7 mm Hg, S aO 2 95.1 6 26.9%. The mean 6 SD length of time to the first change in F IO 2 from the time a subject met the weaning criteria was 9.1 6 10.6 h (range 1-39 h; interquartile range 2-13 h). CONCLUSIONS: Subjects admitted to the medical ICU who were intubated, mechanically ventilated, and placed on the oxygen therapy protocol experienced a significant delay in oxygen weaning. Closer monitoring and adherence to the oxygen-weaning protocol should be considered to reduce the potential risk for hyperoxia. Key words: oxygen weaning; weaning protocols; oxygen titration protocol; patient-driven protocols; protocol adherence; weaning indices.