Cerebral oxygenation during orthostatic stress in patients with Precapillary Pulmonary Hypertension

• Grant number: 25/08059-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2025
• End date: August 31, 2026
• Field of knowledge: Biological Sciences - Physiology - General Physiology
• Principal Investigator: Bruno Moreira Silva
• Grantee: Pedro Henrique Gonçalves da Silva
• Host Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

Pre-Capillary Pulmonary Hypertension (PcPH) is a subtype of Pulmonary Hypertension that affects the pulmonary arterial circulation and the right heart. This vascular disorder is characterized by increased resistance and pulmonary vascular remodeling, which-if left untreated-lead to right ventricular failure and death. Due to a fragile cardiovascular system, it is plausible that the regulation of systemic blood pressure and cerebral oxygenation is particularly sensitive and challenging in individuals with pulmonary hypertension, especially in contexts involving abrupt pressure shifts that require rapid activation of counter-regulatory mechanisms. The active transition from the supine to the upright position is one such activity that triggers an acute stress, demanding compensatory responses to maintain adequate cerebral perfusion and blood pressure, due to the gravitational redistribution of blood volume. However, pathophysiological aspects-such as the cerebral oxygenation response to active orthostatic stress-remain poorly understood in this population. Thus, the aim of the present research project is to investigate cerebral oxygenation and its relationship to symptom manifestation during orthostatic stress in patients with PcPH. To this end, individuals of both sexes, aged 18 and older, diagnosed with Pulmonary Arterial Hypertension or Chronic Thromboembolic Pulmonary Hypertension who meet the inclusion criteria will be invited to participate in the study. Cerebral oxygenation will be assessed noninvasively using near-infrared spectroscopy (NIRS), through a sensor placed on the patients' forehead during the execution of the active orthostatic stress protocol. Our hypothesis is that cerebral oxygenation in PcPH patients decreases during active orthostatic stress. We also expect that the cerebral oxygenation response to active orthostatism will correlate with symptom manifestation in these patients.