Acute hyperoxic challenge improves haemodynamics & Pulmonary vascular stiffness in interstitial lung disease-associated pulmonary hypertension

Abstract

Introduction: Pulmonary hypertension (PH) is a potentially severe complication of interstitial lung disease (ILD) that results from multiple mechanisms, including hypoxic pulmonary vasoconstriction. Because hyperoxia may have vasodilatory effects, we tested whether acute hyperoxia improved hemodynamics and pulmonary vascular stiffness in an ILD-PH cohort.

Methods: Patients with ILD and suspected PH underwent right heart catheterization (RHC). Patients with low peripheral oxygen saturation (SpO₂) were administered supplemental O₂ to achieve an SpO₂ ≥ 90% and then haemodynamic data were collected. Hemodynamics were repeated after 100% FiO₂ for 5 minutes.

Results: The cohort comprised 23 patients with ILD and RHC-proven PH (mean pulmonary artery pressure (mPAP) 33±7.34 mmHg, pulmonary artery occlusion pressure 12±2.5 mmHg, pulmonary vascular resistance (PVR) 4.9±2.8 Wood's Units (WU), and capacitance 2.07±0.89 mL/mmHg. 11 patients required supplemental oxygen to achieve an SpO₂>90% The baseline mean SpO₂ was 94.4%; 3 patients were hypoxic (PaO₂<8kPa). 100% FiO₂ improved SpO₂ (+4.1%), reduced mPAP (-2.7±4.3 mmHg, p=0.002), PVR (-0.78±1.24 WU, p=0.0007), and pulmonary vascular stiffness (increased capacitance) (+0.39±0.48 mmHg/mL, p<0.0001).

Discussion: Hyperoxia acutely improves hemodynamics and vascular stiffness even in the absence of hypoxaemia, suggesting oxygen supplementation may be beneficial in normoxic ILD PH. Because proximal pulmonary arterial remodeling contributes significantly to overall vascular stiffness, these acute changes in stiffness with hyperoxia suggest previously undescribed improvements in proximal arterial mechanics.