Contrasting the physiological effects of heliox and oxygen during exercise in a patient with advanced COPD

Abstract

In COPD patients the ergogenic effect of heliox or oxygen breathing might be related both to improvements in ventilatory parameters (that lessen dyspnoea) and to enhanced oxygen delivery to respiratory and locomotor muscles http://bit.ly/2JlJBTc.

Figure 1

Central haemodynamic responses. a) Cardiac output; b) systemic vascular conductance; c) systemic C_aO2; and d) systemic oxygen delivery recorded at rest, at the time of exhaustion in room air (isotime), and at the limit of exercise tolerance (tlim) while breathing normoxic heliox, pure (100%) oxygen or room air. Isotime data are those obtained on normoxic heliox or 100% oxygen at the same time as at the limit of exercise tolerance on room air.

Figure 2

Quadriceps, intercostal, and abdominal muscle haemodynamic responses. a) Quadriceps muscle blood flow; b) intercostal muscle blood flow; c) abdominal muscle blood flow; d) quadriceps muscle oxygen delivery; e) intercostal muscle oxygen delivery; and f) abdominal muscle oxygen delivery recorded at rest, at the time of exhaustion in room air (isotime), and t_lim breathing normoxic heliox, pure (100%) oxygen or room air. Isotime data are those obtained on normoxic heliox or 100% oxygen at the same time as at the limit of exercise tolerance on room air.

Figure 3

Quadriceps, intercostal, and abdominal muscle oxygenation responses and metabolic responses. a) Quadriceps muscle oxygen saturation; b) intercostal muscle oxygen saturation; c) abdominal muscle oxygen saturation; and d) arterial lactate concentration recorded at rest, at the time of exhaustion in room air (isotime), and t_lim while patient breathed norm­oxic heliox, pure (100%) oxygen or room air. Isotime data are those obtained on normoxic heliox or 100% oxygen at the same time as at the limit of exercise tolerance on room air.

Figure 4

A schematic representation conceptualising the acute physiological responses a patient with COPD exhibits during exercise breathing heliox or oxygen compared with exercise in room air. t_E: expiratory time; DH: dynamic hyperinflation; CO: cardiac output; O₂DEL: oxygen delivery; SVC: systemic vascular conductance; EMG: electromyography. ^#: profoundly in hypoxaemic patients. Figure partially created using BioRender.