BACKGROUND: Respiratory muscle unloading during exercise could improve locomotor muscle oxygenation by increasing oxygen delivery (higher cardiac output and/or arterial oxygen content) in patients with chronic obstructive pulmonary disease (COPD). METHODS: Sixteen non-hypoxaemic men (forced expiratory volume in 1 s 42.2 (13.9)% predicted) undertook, on different days, two constant work rate (70-80% peak) exercise tests receiving proportional assisted ventilation (PAV) or sham ventilation. Relative changes (Delta%) in deoxyhaemoglobin (HHb), oxyhaemoglobin (O(2)Hb), tissue oxygenation index (TOI) and total haemoglobin (Hb(tot)) in the vastus lateralis muscle were measured by near-infrared spectroscopy. In order to estimate oxygen delivery (Do(2)est, l/min), cardiac output and oxygen saturation (Spo(2)) were continuously monitored by impedance cardiography and pulse oximetry, respectively. RESULTS: Exercise tolerance (Tlim) and oxygen uptake were increased with PAV compared with sham ventilation. In contrast, end-exercise blood lactate/Tlim and leg effort/Tlim ratios were lower with PAV (p<0.05). There were no between-treatment differences in cardiac output and Spo(2) either at submaximal exercise or at Tlim (ie, Do(2)est remained unchanged with PAV; p>0.05). Leg muscle oxygenation, however, was significantly enhanced with PAV as the exercise-related decrease in Delta(O(2)Hb)% was lessened and TOI was improved; moreover, Delta(Hb(tot))%, an index of local blood volume, was increased compared with sham ventilation (p<0.01). CONCLUSIONS: Respiratory muscle unloading during high-intensity exercise can improve peripheral muscle oxygenation despite unaltered systemic Do(2 )in patients with advanced COPD. These findings might indicate that a fraction of the available cardiac output had been redirected from ventilatory to appendicular muscles as a consequence of respiratory muscle unloading.
BACKGROUND: Respiratory muscle unloading during exercise could improve locomotor muscle oxygenation by increasing oxygen delivery (higher cardiac output and/or arterial oxygen content) in patients with chronic obstructive pulmonary disease (COPD). METHODS: Sixteen non-hypoxaemic men (forced expiratory volume in 1 s 42.2 (13.9)% predicted) undertook, on different days, two constant work rate (70-80% peak) exercise tests receiving proportional assisted ventilation (PAV) or sham ventilation. Relative changes (Delta%) in deoxyhaemoglobin (HHb), oxyhaemoglobin (O(2)Hb), tissue oxygenation index (TOI) and total haemoglobin (Hb(tot)) in the vastus lateralis muscle were measured by near-infrared spectroscopy. In order to estimate oxygen delivery (Do(2)est, l/min), cardiac output and oxygen saturation (Spo(2)) were continuously monitored by impedance cardiography and pulse oximetry, respectively. RESULTS: Exercise tolerance (Tlim) and oxygen uptake were increased with PAV compared with sham ventilation. In contrast, end-exercise blood lactate/Tlim and leg effort/Tlim ratios were lower with PAV (p<0.05). There were no between-treatment differences in cardiac output and Spo(2) either at submaximal exercise or at Tlim (ie, Do(2)est remained unchanged with PAV; p>0.05). Leg muscle oxygenation, however, was significantly enhanced with PAV as the exercise-related decrease in Delta(O(2)Hb)% was lessened and TOI was improved; moreover, Delta(Hb(tot))%, an index of local blood volume, was increased compared with sham ventilation (p<0.01). CONCLUSIONS: Respiratory muscle unloading during high-intensity exercise can improve peripheral muscle oxygenation despite unaltered systemic Do(2 )in patients with advanced COPD. These findings might indicate that a fraction of the available cardiac output had been redirected from ventilatory to appendicular muscles as a consequence of respiratory muscle unloading.
Authors: Markus Amann; Mark S Regan; Majd Kobitary; Marlowe W Eldridge; Urs Boutellier; David F Pegelow; Jerome A Dempsey Journal: Am J Physiol Regul Integr Comp Physiol Date: 2010-05-05 Impact factor: 3.619
Authors: Diego de Paiva Azevedo; Wladimir Musetti Medeiros; Flávia Fernandes Manfredi de Freitas; Cesar Ferreira Amorim; Ana Cristina Oliveira Gimenes; Jose Alberto Neder; Luciana Dias Chiavegato Journal: Eur J Appl Physiol Date: 2016-07-28 Impact factor: 3.078
Authors: Cristino Carneiro Oliveira; Cláudia Regina Carrascosa; Audrey Borghi-Silva; Danilo C Berton; Fernando Queiroga; Eloara M V Ferreira; Luiz E Nery; J Alberto Neder; J Alberto Neder Journal: Eur J Appl Physiol Date: 2010-03-06 Impact factor: 3.078
Authors: François Maltais; Marc Decramer; Richard Casaburi; Esther Barreiro; Yan Burelle; Richard Debigaré; P N Richard Dekhuijzen; Frits Franssen; Ghislaine Gayan-Ramirez; Joaquim Gea; Harry R Gosker; Rik Gosselink; Maurice Hayot; Sabah N A Hussain; Wim Janssens; Micheal I Polkey; Josep Roca; Didier Saey; Annemie M W J Schols; Martijn A Spruit; Michael Steiner; Tanja Taivassalo; Thierry Troosters; Ioannis Vogiatzis; Peter D Wagner Journal: Am J Respir Crit Care Med Date: 2014-05-01 Impact factor: 21.405