Browsing by Autor "Yves Allemann"

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Acute and Chronic Altitude-Induced Cognitive Dysfunction in Children and Adolescents
(Elsevier BV, 2015) Stefano F. Rimoldi; Emrush Rexhaj; Hervé Duplain; Sébastien Urben; Joël Billieux; Yves Allemann; Catherine Romero; Alejandro Ayaviri; Carlos E. Salinas; Mercedes Villena
Exaggerated exercise‐induced pulmonary hypertension in Chronic Mountain Sickness
(Wiley, 2007) Jonathan Bloch; Thomas Stüber; Marcos Schwab; Pierre‐Yves Jayet; Sébastien Thalmann; Hilde Spielvogel; Carlos E Salinas Salmón; Mercedes Villena; Yves Allemann; Cláudio Sartori
Excessive erythrocytosis is a hallmark of Chronic Mountain Sickness (CMS). By scavenging nitric oxide (NO), erythrocytosis may impair NO bioavailability, and, in turn, increase pulmonary artery tone. Little is known, however, about pulmonary vasoregulation at rest and during exercise in CMS. We measured systolic pulmonary artery pressure (echocardiography) at rest and during exercise (bicycle ergometer) in 20 male subjects with CMS (primary erythrocytosis, Hb level >20g/dl) and 40 healthy controls in La Paz (3600 m). All subjects were Bolivian high‐altitude natives. Hemoglobin levels, as expected, were markedly higher in CMS than in control subjects (22.1±2.0 vs. 16.7±0.8, mean±SD, p<0.001), and were associated with an increased resting systolic pulmonary artery pressure (35.5±8.7 vs. 29.5±4.9 mm Hg, p<0.002). Most importantly, the exercise‐induced increase in pulmonary artery pressure was roughly twice as large in patients with CMS than in control subjects: at 50 Watts systolic‐pulmonary artery pressure increased to 59.3±14.5 mm Hg in the patients, but to only 43.3±8.3 mm Hg in the control subjects (P<0.001). These data provide the first evidence for a strikingly exaggerated pulmonary artery pressure response to mild exercise in CMS. This exaggerated pulmonary vasoconstrictor response, which is possibly related to impaired NO biodisponibility, may contribute to impaired exercise tolerance in CMS.
Exercise Induces Rapid Interstitial Lung Water Accumulation in Patients With Chronic Mountain Sickness
(Elsevier BV, 2011) Lorenza Pratali; Stefano F. Rimoldi; Emrush Rexhaj; Damian Hutter; Francesco Faita; Carlos Salinas Salmón; Mercedes Villena; Rosa Sicari; Eugenio Picano; Yves Allemann
Increasing respiratory dead space improves sleep disordered breathing and hypoxemia in patients with chronic mountain sickness
(Wiley, 2011) Emrush Rexhaj; Stefano F. Rimoldi; Pierre‐Yves Jayet; Alban Lovis; Daniela Andries; Carlos Salinas Salmón; Mercedes Villena; Yves Allemann; Raphaël Heinzer; Raphaël Heinzer
Chronic mountain sickness (CMS) is a major public health problem characterized by chronic hypoxemia and erythrocytosis. The underlying mechanism is unknown. Sleep disordered breathing (SDB) is frequent at high altitude. We recently found that increasing the respiratory dead space markedly improves SDB in mountaineers. We speculated that this procedure also has beneficial effects in CMS patients. To test this hypothesis, in 17 male Bolivian high-altitude dwellers (56±9 y) suffering from CMS full night sleep recordings were obtained in random order during one night spent with and one without a 500 ml increase in respiratory dead space through a custom designed full face mask. Recordings were also obtained in 6 control subjects. The major new findings were two-fold; a) CMS patients present markedly more severe SDB and hypoxemia (P<.01) than control subjects; and b) added dead space dramatically improved SDB in CMS patients, as evidenced by a decrease of the apnea/hypopnea (P<.01), hypopnea (P=.01) and oxygen desaturation (P<.01) indexes, and an increase of the nocturnal oxygen saturation (P=.01). The procedure was well tolerated. Here, we show for the first time that increasing respiratory dead space dramatically improves SDB in patients with CMS. We speculate that its long-term use will improve erythrocytosis and pulmonary hypertension and offer an inexpensive treatment for this major public health problem.
Lack of protection against hypoxic pulmonary hypertension in Bolivian high altitude natives?
(Wiley, 2007) Jonathan Bloch; Marcos Schwab; Thomas Stüber; Pierre‐Yves Jayet; Carlos E Salinas Salmón; Hilde Spielvogel; Mercedes Villena; Yves Allemann; Cláudio Sartori; Urs Scherrer
Pulmonary artery pressure increases at high altitude. It has been speculated that augmented respiratory synthesis of the vasodilator nitric oxide (NO) protects high‐altitude natives from pulmonary hypertension, but direct evidence for this speculation is lacking. We, therefore, measured systolic pulmonary artery pressure (right ventricular to right atrial pressure gradient, Doppler‐echocardiography), exhaled NO (NIOX MINO®) and oxygen saturation in 34 healthy adult Bolivian high altitude natives and in 35 healthy age‐ and sex‐matched, well acclimatized European low altitude natives living at high‐altitude (3′600 m). Mean±SD systolic pulmonary artery pressure (29.3±5.9 mm Hg, range 16 to 40, vs. 29.6±4.9 mm Hg, range 22 to 42), exhaled NO (19.2±7.2 ppb, range 8 to 41, vs. 22.5±9.5 ppb, range 9 to 52) and arterial oxygen saturation (92.4±3.2, range 80 to 97, vs. 92.5±2.4, range 87 to 97) were similar in Bolivians and Europeans. There was no relationship between pulmonary artery pressure and respiratory NO neither in Bolivians (r=0.14, p=0.44), nor in Europeans (r=0.19, p=0.29). These findings provide the first evidence that at high altitude, pulmonary artery pressure in European low altitude natives is not elevated, but similar to the one measured in Bolivian high altitude natives. These findings challenge the concept that Bolivian high altitude natives are protected from hypoxic pulmonary hypertension.
Novel Insights into Cardiovascular Regulation in Patients with Chronic Mountain Sickness
(Springer Nature, 2016) Stefano F. Rimoldi; Emrush Rexhaj; Mercedes Villena; Carlos Salinas Salmón; Yves Allemann; Urs Scherrer; Cláudio Sartori
Oxidative-Nitrosative Stress and Systemic Vascular Function in Highlanders With and Without Exaggerated Hypoxemia
(Elsevier BV, 2013) Damian M. Bailey; Stefano F. Rimoldi; Emrush Rexhaj; Lorenza Pratali; Carlos Salinas Salmón; Mercedes Villena; Jane McEneny; Ian Young; Pascal Nicod; Yves Allemann
Pulmonary-Artery Pressure and Exhaled Nitric Oxide in Bolivian and Caucasian High Altitude Dwellers
(Mary Ann Liebert, Inc., 2008) Marcos Schwab; Pierre‐Yves Jayet; Thomas Stüber; Carlos E. Salinas; Jonathan Bloch; Hilde Spielvogel; Mercedes Villena; Yves Allemann; Cláudio Sartori; Urs Scherrer
There is evidence that high altitude populations may be better protected from hypoxic pulmonary hypertension than low altitude natives, but the underlying mechanism is incompletely understood. In Tibetans, increased pulmonary respiratory NO synthesis attenuates hypoxic pulmonary hypertension. It has been speculated that this mechanism may represent a generalized high altitude adaptation pattern, but direct evidence for this speculation is lacking. We therefore measured systolic pulmonary-artery pressure (Doppler chocardiography) and exhaled nitric oxide (NO) in 34 healthy, middle-aged Bolivian high altitude natives and in 34 age- and sex-matched, well-acclimatized Caucasian low altitude natives living at high altitude (3600 m). The mean+/-SD systolic right ventricular to right atrial pressure gradient (24.3+/-5.9 vs. 24.7+/-4.9 mmHg) and exhaled NO (19.2+/-7.2 vs. 22.5+/-9.5 ppb) were similar in Bolivians and Caucasians. There was no relationship between pulmonary-artery pressure and respiratory NO in the two groups. These findings provide no evidence that Bolivian high altitude natives are better protected from hypoxic pulmonary hypertension than Caucasian low altitude natives and suggest that attenuation of pulmonary hypertension by increased respiratory NO synthesis may not represent a universal adaptation pattern in highaltitude populations.
RV Contractility and Exercise-Induced Pulmonary Hypertension in Chronic Mountain Sickness
(Elsevier BV, 2013) Lorenza Pratali; Yves Allemann; Stefano F. Rimoldi; Francesco Faita; Damian Hutter; Emrush Rexhaj; Roman Brenner; Damian M. Bailey; Cláudio Sartori; Carlos Salinas Salmón
Sleep-Disordered Breathing and Vascular Function in Patients With Chronic Mountain Sickness and Healthy High-Altitude Dwellers
(Elsevier BV, 2015) Emrush Rexhaj; Stefano F. Rimoldi; Lorenza Pratali; Roman Brenner; Daniela Andries; Rodrigo Soria; Carlos E. Salinas; Mercedes Villena; Catherine Romero; Yves Allemann
Systemic Vascular Dysfunction in Patients With Chronic Mountain Sickness
(Elsevier BV, 2011) Stefano F. Rimoldi; Emrush Rexhaj; Lorenza Pratali; Damian M. Bailey; Damian Hutter; Francesco Faita; Carlos Salinas Salmón; Mercedes Villena; Pascal Nicod; Yves Allemann