Basic Clin Pharmacol Toxicol. 2025 Apr;136(4):e70019. doi: 10.1111/bcpt.70019.
ABSTRACT
BACKGROUND: The relational equation for predicting arterial oxygen saturation (SaO2) with a partial pressure of oxygen (PaO2) has been described and used in clinical settings. However, the equation has limitations as it was derived empirically. This study aimed to assess the relationship between PaO2 and SaO2 using a turnover model.
MATERIAL AND METHODS: In a controlled desaturation study to assess the accuracy of a pulse oximeter, volunteers (n = 12) breathed hypoxic gas mixtures via a mouthpiece. Various target SaO2 values were achieved within the range of 70%-100%. PaO2 and SaO2 were measured using a CO-oximeter. A turnover model was fitted to PaO2-SaO2 pair data. The performance of the two SaO2 prediction methods (conventional formula and turnover model) was evaluated using additional volunteer data not used in the model-building process.
RESULTS: The pharmacodynamic parameters were as follows: kout (1/min) = 4.45 for Asians, 0.93 for Africans, Imax = 0.837 and IC50 (mmHg) = 79.2%, γ = 5.24. PaCO2 and pH were not significant covariates. The median prediction and median absolute prediction error were 5.6% and 5.7%, respectively, for the conventional formula, and 0.1% and 1.2%, respectively, for the turnover model.
CONCLUSION: The relationship between PaO2 and SaO2 was better explained by the turnover model than by the conventional formula within the 70%-100% SaO2 range.
PMID:40099357 | DOI:10.1111/bcpt.70019