Effects of altitude on arterial partial pressure of carbon dioxide and the incidence of central sleep apnea in patients with chronic heart failure
Li Qun
Gong Bu
Wang Xiaoxia
Chen Peng
Abstract：Objective To analyze the differences in arterial partial pressure of carbon dioxide(PaCO2)and the incidence of central sleep apnea(CSA)in patients with chronic heart failure(CHF)at different altitudes,and to explore the related influencing factors for the occurrence of CSA.Methods A total of 78 CHF patients admitted from January 2022 to March 2025 were enrolled,including 48 cases from the Third People's Hospital of Chengdu,Sichuan Province(residents living at a mean altitude of 500 m,low-altitude group)and 30 cases from Litang County People's Hospital,Sichuan Province(residents living continuously at an altitude of 3 900-4 100 m for≥5 years,high-altitude group).The clinical data and relevant clinical indicators of the patients were collected.Multivariate Logistic regression analysis was used to screen the independent risk factors for CSA.Two-way analysis of variance was adopted to evaluate the effects of PaCO2 and altitude on the central sleep apnea index(CSAI),micro-arousal index(MAI)and Epworth sleepiness scale(ESS)score.Receiver operating characteristic(ROC)curves were plotted to analyze the predictive efficacy of PaCO2 for CSA in CHF patients with different heart failure locations at different altitudes.Results Multivariate Logistic regression analysis showed that left heart failure,left ventricular ejection fraction ≤40％,PaCO2 ≤38 mmHg and tricuspid annular systolic excursion ≤12 mm were all independent risk factors for CSA(all P＜0.05).Regardless of PaCO2 levels,there were statistically significant differences in CSAI and ESS scores between the different altitude groups(all P＜0.001).CSAI and ESS scores increased gradually with the elevation of altitude,and there was an interactive effect of altitude and PaCO2 on CSAI(all P＜0.001).Regardless of altitude,there was a statistically significant difference in MAI between the different PaCO2 groups(P＜0.001).MAI increased gradually with the rise of PaCO2,and altitude and PaCO2 had an interactive effect on CSAI(P＜0.001).ROC curve analysis showed that when PaCO2 ≤36.8 mmHg,the area under the curve(AUC)for predicting CSA in patients with left heart failure was 0.918;when PaCO2 ≤35.2 mmHg,the AUC for predicting CSA in patients with right heart failure was 1.000.For patients in the high-altitude area,when PaCO2 ≤36.9 mmHg,the AUC for predicting CSA in patients with left heart failure was 0.964;when PaCO236.0 mmHg,the AUC for predicting CSA in patients with right heart failure was 0.972.Conclusion Altitude and PaCO2 have an interactive effect on CSA-related indicators in CHF patients.The risk of CSA is higher in the high-altitude environment,and PaCO2 can serve as an important indicator for predicting CSA.
Keywords：Chronic heart failureCentral sleep apneaArterial partial pressure of carbon dioxide
Publication Date：2026-05-18
Online Publishing Date：2026-09-14(First online date of this platform, not the publication date of the document)
Pages：6( 661-666 )