Respiratory physiology & neurobiology
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Respir Physiol Neurobiol · Nov 2007
Randomized Controlled Trial Clinical TrialEffect of sildenafil on hypoxia-induced changes in pulmonary circulation and right ventricular function.
Hypoxia leads to pulmonary vasoconstriction in healthy men. However, the consequences on right ventricular function are not known. The effects of hypoxia on systolic pulmonary artery pressure (sPAP) and right ventricular function index (TEI) were assessed by Doppler echocardiography. ⋯ At 5245 m sPAP was 29.1(1.7) and TEI was 0.43(0.05) in the placebo group, while in the sildenafil group, both sPAP and TEI were reduced to 22(1.5) mm Hg and 0.23(0.03) (each p<0.005), respectively. We conclude that in healthy individuals, exposure to acute hypoxia and sojourns at high altitude result in a small but significant increase in sPAP accompanied by an impairment of right ventricular function. Sildenafil significantly decreases sPAP and improves right ventricular function.
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Respir Physiol Neurobiol · Nov 2007
Poor compensatory hyperventilation in morbidly obese women at peak exercise.
This study was designed to compare differences in pulmonary gas exchange at rest and at peak exercise in two groups of women: (1) physically active, non-obese women and (2) women with morbid obesity. Fourteen morbidly obese women (body mass index or BMI=49+/-7 kg/m2; peak oxygen consumption or VO2 peak=14+/-2 ml/(kg min)) and 14 physically active non-obese women (BMI=22+/-2 kg/m2; VO2 peak=50+/-6 ml/(kg min)) performed an incremental, ramped exercise test to exhaustion on a cycle ergometer. Arterial blood was sampled at rest and at peak exercise. ⋯ Only the non-obese women showed a decrease in PaCO2 rest to peak exercise (-5+/-3 mmHg). The slope between heart rate and VO2 during exercise was higher in the morbidly obese compared to non-obese women indicating that for the same absolute increase in VO2 a larger increase in heart rate is needed, demonstrating poorer cardiac efficiency in obese women. In conclusion, morbidly obese women have poorer exercise capacity, cardiac efficiency, and compensatory hyperventilation at peak exercise, and poorer gas exchange at rest compared to physically active, non-obese women.