Definition of Acute Respiratory Distress Syndrome on the Plateau of Xining, Qinghai: A Verification of the Berlin Definition Altitude-PaO2/FiO2-Corrected Criteria

Abstract

Background: Acute respiratory distress syndrome (ARDS) is a common critical respiratory illness. Hypoxia at high altitude is a factor that influences the progression of ARDS. Currently, we lack clear diagnostic criteria for high-altitude ARDS. The purpose of this study was to determine the value of the application of the Berlin Definition altitude-PaO₂/FiO₂-corrected criteria for ARDS in Xining, Qinghai (2,261 m).

Methods: We retrospectively analyzed the clinical data of patients with ARDS admitted to the Department of Critical Care Medicine of the Affiliated Hospital of Qinghai University from January 2018 to December 2018. The severity of ARDS was categorized according to the Berlin Definition, Berlin Definition altitude-PaO₂/FiO₂-corrected criteria, and the diagnostic criteria for acute lung injury (ALI)/ARDS at high altitudes in Western China (Zhang criteria). In addition, the differences between the three criteria were compared.

Results: Among 1,221 patients, 512 were treated with mechanical ventilation. In addition, 253 met the Berlin Definition, including 49 (19.77%) with mild ARDS, 148 (58.50%) with moderate ARDS, and 56 (22.13%) with severe ARDS. A total of 229 patients met the altitude-PaO₂/FiO₂-corrected criteria, including 107 with mild ARDS (46.72%), 84 with moderate ARDS (36.68%), and 38 (16.59%) with severe ARDS. Intensive care unit (ICU) mortality increased with the severity of ARDS (mild, 17.76%; moderate, 21.43%; and severe, 47.37%). Twenty-eight-day mortality increased with worsening ARDS (mild 23.36% vs. moderate 44.05% vs. severe 63.16%) (p < 0.001). There were 204 patients who met the Zhang criteria, including 87 (42.65%) with acute lung injury and 117 (57.35%) with ARDS. The area under receiver operating characteristics (AUROCs) of the Berlin Definition, the altitude-P/F-corrected criteria, and the Zhang criteria were 0.6675 (95% CI 0.5866-0.7484), 0.6216 (95% CI 0.5317-0.7116), and 0.6050 (95% CI 0.5084-0.7016), respectively. There were no statistically significant differences between the three diagnostic criteria.

Conclusion: For Xining, Qinghai, the altitude-PaO₂/FiO₂-corrected criteria for ARDS can distinguish the severity of ARDS, but these results need to be confirmed in a larger sample and in multicenter clinical studies.

Clinical trial registration: ClinicalTrials.gov, identifier: NCT04199650.

Keywords: ARDS; Berlin Definition; P/F; acute respiratory distress syndrome; high altitude.

Figure 1

Flow diagram of patient screening and enrollment. P/F, PaO₂/FiO₂; P/F-corrected criteria, The Berlin Definition altitude-PaO₂/FiO₂-corrected criteria; Zhang criteria, The diagnostic criteria for ALI/ARDS at high altitudes in Western China; Berlin Definition, The Berlin Definition of acute respiratory distress syndrome; ALI, acute lung injury; ARDS, acute respiratory distress syndrome.

Figure 2

Comparison of the area under the receiver operating characteristic (ROC) curve of three different ARDS criteria for the ICU case fatality rate. Here were no statistically significant differences between the three diagnostic criteria. Berlin Definition, The Berlin Definition of acute respiratory distress syndrome; P/F-corrected criteria, The Berlin Definition altitude-PaO₂/FiO₂-corrected criteria; Zhang criteria, The diagnostic criteria for ALI/ARDS at high altitudes in Western China.

Figure 3

Venn diagram of patient distribution for different criteria. Berlin Definition, The Berlin Definition of acute respiratory distress syndrome; P/F-corrected criteria, The Berlin Definition altitude-PaO₂/FiO₂-corrected criteria; Zhang criteria, The diagnostic criteria for ALI/ARDS at high altitudes in Western China; The P/F was < 200 mmHg in 204 patients, 25 patients with a P/F between 200 and 253 mmHg, and 24 patients with 253 ≥ P/F < 300.