Reference values of arterial blood gas index in adult respiratory failure in high altitude area

The arterial blood gas (ABG) reference values determined at or near sea level may not be applicable in high-altitude areas. This study investigated the reference values of the ABG indexes for adult respiratory failure in the Tibetan Autonomous Prefecture in Yunnan Province, China. This prospective study enrolled adult patients with respiratory failure at the internal medicine department of Diqing Tibetan Autonomous Prefecture (altitude: 3294 m) in Yunnan province between November 2019 and March 2022. There were 112 cases of type I respiratory failure (median age of 56 years, 61 males) and 91 with type II respiratory failure (median age of 59 years, 42 males). The reference value of PaO₂ for type I respiratory failure was 46.9 mmHg (AUC 1.000, 95% CI 1.000-1.000, sensitivity and specificity of 100%, P < 0.001). The reference value of PaCO₂ for type II respiratory failure was 38.1 mmHg (AUC 0.871, 95% CI 0.823-0.920, sensitivity and specificity of 95.6% and 60.4%, respectively, P < 0.001). It might be recommended that the reference values of PaO₂ and PaCO₂ for type I and II respiratory failure be 46.9 and 38.1 mmHg, respectively, in high-altitude areas.