Abstract
We evaluated the short-term variability of Pao 2, Paco 2, pulse oximeter saturation (Spo 2), and end-tidalPco 2 (Petco 2) 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.Spo 2 andPetco 2 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 Pao 2 (95th percentile = 9.8%), 0.5% forSpo 2 (95th percentile = 1.4%), 2.8% for Paco 2 (95th percentile = 7.4%), and 2.4% forPetco 2 (95th percentile = 7.1%). The overall correlation between Paco 2 andPetco 2 wasr=0.80, and the mean difference between Paco 2 andPetco 2 was 0.9±3.6 mm Hg. The variability ofPetco 2 was similar to the variability of Paco 2. However, the variability of Pao 2 was considerably greater than that ofSpo 2, 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,Spo 2, andPetco 2 should be considered when these values are clinically interpreted.
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Hess, D., Agarwal, N.N. Variability of blood gases, pulse oximeter saturation, and end-tidal carbon dioxide pressure in stable, mechanically ventilated trauma patients. J Clin Monitor Comput 8, 111–115 (1992). https://doi.org/10.1007/BF01617428
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DOI: https://doi.org/10.1007/BF01617428