Exercise-induced oxyhemoglobin desaturation is an independent risk factor for sustained nocturnal hypoxemia in adults with precapillary pulmonary hypertension: A cross-sectional study

Abstract

Background: Nocturnal hypoxemia (NH) negatively impacts the prognosis of several chronic cardiopulmonary diseases.

Objectives: To assess the risk factors associated with sustained NH in adults with precapillary pulmonary hypertension (pPH).

Methods: This cross-sectional study was performed between June 2021 and June 2024. Outpatients with a hemodynamic diagnosis of pPH (Groups 1 and 4) were consecutively recruited. Sustained NH was defined as ≥ 30 % of the percentage of time spent with oxygen saturation (SpO₂) <90 % during a home sleep apnea test (HSAT). Clinical, laboratory, hemodynamic, echocardiographic, functional, and exercise-related variables were collected blindly regarding the HSAT data. We considered a difference in SpO₂ [resting - final] (Δ SpO₂) ≥ 3 % as indicative of exercise-induced oxyhemoglobin desaturation (EID) by the six-minute walk test. Multiple logistic regression analysis was used to identify possible predictive factors for the occurrence of NH.

Results: Fifty-two pPH adults were included (71.2 % were females). Thirty-one patients (59.6 %) were classified as having NH. In the univariate logistic regression analysis, four parameters were identified as risk factors for the presence of NH: mean pulmonary artery pressure (p = 0.023), right atrial mean pressure (p = 0.037), systolic pulmonary arterial pressure (p = 0.042) and EID (p = 0.003). However, only EID was an independent predictor for detecting NH with an adjusted odds ratio of 10.590 (95 % confidence interval: 1.095-102.420); p = 0.042.

Conclusions: EID is an easily implementable risk factor for prolonged NH, suggesting that adults with pPH who experience EID have a high probability of also experiencing NH.

Keywords: 6-minute walk test; Exercise-induced oxyhemoglobin desaturation; Nocturnal hypoxemia; Pulmonary hypertension.