Kinetics of skeletal muscle O-2 delivery and utilization at the onset of heavy-intensity exercise in pulmonary arterial hypertension

Impaired O-2 delivery relative to O-2 demands at the onset of exercise might influence the response profile of muscle fractional O-2 extraction (congruent to Delta[deoxy-Hb/Mb] by near-infrared spectroscopy) either by accelerating its rate of increase or creating an overshoot'' (OS) in patients with pulmonary arterial hypertension (PAH). We therefore assessed the kinetics of O-2 uptake (V) over dot O-2), Delta[deoxy-Hb/Mb] in the vastus lateralis, and heart rate (HR) at the onset of heavy-intensity exercise in 14 females with PAH (connective tissue disease, IPAH, portal hypertension, and acquired immunodeficiency syndrome) and 11 age-and gender-matched controls. Patients had slower (V) over dot O-2 and HR dynamics than controls (tau(V) over dot O-2 = 62.7 +/- 15.2 s vs. 41.0 +/- 13.8 s and t(1/2) -HR = 61.3 +/- 16.6 s vs. 43.4 +/- 8.8 s, respectively; p < 0.01). No study participant had a significant reduction in oxyhemoglobin saturation. in OS(-) subjects (6 patients and 7 controls), the kinetics of Delta[deoxy-Hb/Mb] relative to (V) over dot O-2 were faster in patients (p = 0.05). Larger area under the OS and slower kinetics (MRT) of the downward component indicated greater O-2 delivery-to-utilization mismatch in OS(+) patients versus OS(+) controls (477.4 +/- 330.0 vs. 78.1 +/- 65.6 a.u. and 74.6 +/- 18.8 vs. 46.0 +/- 17.0 s, respectively; p < 0.05). Resting pulmonary vascular resistance was higher in OS(+) than OS(-) patients (23.1 +/- 12.0 vs. 10.7 +/- 4.0 Woods, respectively; p < 0.05). We conclude that microvascular O-2 delivery-to-utilization inequalities slowed the rate of adaptation of aerobic metabolism at the start of heavy-intensity exercise in women with PAH.Universidade Federal de São Paulo, Paulista Sch Med UNIFESP EPM, Pulm Funct & Clin Exercise Physiol Unit SEFICE, Div Resp,Dept Med, BR-04020050 São Paulo, BrazilUniversidade Federal de São Paulo, Paulista Sch Med UNIFESP EPM, Pulm Funct & Clin Exercise Physiol Unit SEFICE, Div Resp,Dept Med, BR-04020050 São Paulo, BrazilWeb of Scienc

Peripheral Chemoreflex Regulates Post-exercise Cardiac Vagal Reactivation in Healthy Humans and Patients with Pulmonary Arterial Hypertension

Sao Paulo Research Foundation, FAPESPUniv Fed Sao Paulo, Div Pulm Med, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Physiol, Sao Paulo, BrazilUniv Alberta, Div Pulm Med, Edmonton, AB, CanadaUniv Fed Sao Paulo, Div Pulm Med, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Physiol, Sao Paulo, BrazilFAPESP: 2014/24294-6FAPESP: 2015/22198-2Web of Scienc

Intrapulmonary vascular dilatations are common in portopulmonary hypertension and may be associated with decreased survival

Univ Fed Sao Paulo, Dept Med, Div Resp Dis, Sao Paulo, BrazilUniv Fed Maranhao, Dept Med, Maranhao, BrazilUniv Fed Sao Paulo, Dept Med, Div Resp Dis, Sao Paulo, BrazilWeb of Scienc