| Abstrakt: |
We evaluated the short-term variability of Pao2, Paco2, pulse oximeter saturation (Spo2), and end-tidalPco2 (Petco2) in mechanically ventilated trauma patients. All patients were stable and undisturbed during the evaluation periods. Blood gases were obtained from an arterial catheter 4 times at 20-minute intervals.Spo2 andPetco2 were recorded when the blood gases were obtained. Fifty evaluations were made in 26 patients; 24 patients were evaluated twice, with =24 hours between evaluation periods. Variability was expressed as coefficient of variation (%CV) for each evaluation period. The median %CVs were 3.6% for Pao2 (95th percentile = 9.8%), 0.5% forSpo2 (95th percentile = 1.4%), 2.8% for Paco2 (95th percentile = 7.4%), and 2.4% forPetco2 (95th percentile = 7.1%). The overall correlation between Paco2 andPetco2 wasr=0.80, and the mean difference between Paco2 andPetco2 was 0.9±3.6 mm Hg. The variability ofPetco2 was similar to the variability of Paco2. However, the variability of Pao2 was considerably greater than that ofSpo2, which was probably related to the shape of the oxyhemoglobin dissociation curve and the relatively high saturations of the patients in this study. Variability of blood gases,Spo2, andPetco2 should be considered when these values are clinically interpreted. |
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