title: Cerebral microvascular blood flow and CO2reactivity in pulmonary arterial hypertension.
abstract: Hypocapnia and endothelial dysfunction might impair microvascular cerebral blood flow (CBFmicr) and cerebrovascular reactivity to CO2(CVRCO2). Pulmonary arterial hypertension (PAH) is characteristically associated with chronic alveolar hyperventilation and microvascular endothelial dysfunction. We therefore determined CBFmicr(pre-frontal blood flow index (BFI) by the indocyanine green-near infrared spectroscopy methodology) during hypocapnia and hypercapnia in 25 PAH patients and 10 gender- and age-matched controls. Cerebral BFI was lower in patients than controls at similar transcutaneous PCO2(PtcCO2) levels in both testing conditions. In fact, while BFI increased from hypocapnia to hypercapnia in all controls, it failed to increase in 17/25 (68%) patients. Thus, BFI increased to a lesser extent from hypo to hypercapnia ("Δ") in patients, i.e., they showed lower Δ BFI/Δ PtcCO2ratios than controls. In conclusion, CBFmicrand CVRCO2are lessened in clinically stable, mildly-impaired patients with PAH. These abnormalities might be associated with relevant clinical outcomes (hyperventilation and dyspnea, cognition, cerebrovascular disease) being potentially amenable to pharmacological treatment.
authors: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, Paulista School of Medicine (UNIFESP-EPM), Brazil; Division of Respiratory Diseases, Department of Medicine, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil.
authors: Erika
authors: E
authors: Treptow
authors: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, Paulista School of Medicine (UNIFESP-EPM), Brazil.
authors: Mayron F
authors: MF
authors: Oliveira
authors: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, Paulista School of Medicine (UNIFESP-EPM), Brazil.
authors: Aline
authors: A
authors: Soares
authors: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, Paulista School of Medicine (UNIFESP-EPM), Brazil; Division of Respiratory Diseases, Department of Medicine, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil.
authors: Roberta P
authors: RP
authors: Ramos
authors: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, Paulista School of Medicine (UNIFESP-EPM), Brazil.
authors: Luiz
authors: L
authors: Medina
authors: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, Paulista School of Medicine (UNIFESP-EPM), Brazil.
authors: Rita
authors: R
authors: Lima
authors: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, Paulista School of Medicine (UNIFESP-EPM), Brazil.
authors: Maria Clara
authors: MC
authors: Alencar
authors: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, Paulista School of Medicine (UNIFESP-EPM), Brazil; Division of Respiratory Diseases, Department of Medicine, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil.
authors: Eloara Vieira
authors: EV
authors: Ferreira
authors: Division of Respiratory Diseases, Department of Medicine, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil.
authors: Jaquelina S
authors: JS
authors: Ota-Arakaki
authors: Departamento de Psicobiologia da Universidade Federal de São Paulo (UNIFESP), Brazil.
authors: Sergio
authors: S
authors: Tufik
authors: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, Paulista School of Medicine (UNIFESP-EPM), Brazil.
authors: Luiz E
authors: LE
authors: Nery
authors: Departamento de Psicobiologia da Universidade Federal de São Paulo (UNIFESP), Brazil.
authors: Lia Rita
authors: LR
authors: Bittencourt
authors: Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, Federal University of São Paulo, Paulista School of Medicine (UNIFESP-EPM), Brazil; Division of Respiratory Diseases, Department of Medicine, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil; Laboratory of Clinical Exercise Physiology (LACEP), Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University, Kingston, Canada. Electronic address: nederalb@gmail.com.
authors: J Alberto
authors: JA
authors: Neder
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001785:Blood Gas Monitoring, Transcutaneous; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000097:blood* / Q000503:physiopathology; D006976:Hypertension, Pulmonary / Q000097:blood* / Q000473:pathology / Q000503:physiopathology*; D006985:Hyperventilation / Q000097:blood* / Q000503:physiopathology; D007208:Indocyanine Green / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D019265:Spectroscopy, Near-Infrared; D013147:Spirometry
chemical_list: D007208:Indocyanine Green
keywords: Carbon dioxide; Cerebral blood flow; Near-infrared spectroscopy; Pulmonary hypertension; Ventilation