AUTHOR=Borghi-Silva Audrey , Goulart Cassia da Luz , Carrascosa Cláudia R. , Oliveira Cristino Carneiro , Berton Danilo C. , de Almeida Dirceu Rodrigues , Nery Luiz Eduardo , Arena Ross , Neder J. Alberto 

TITLE=Proportional Assist Ventilation Improves Leg Muscle Reoxygenation After Exercise in Heart Failure With Reduced Ejection Fraction

JOURNAL=Frontiers in Physiology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.685274

DOI=10.3389/fphys.2021.685274

ISSN=1664-042X

ABSTRACT=Background: Respiratory muscle unloading through proportional assist ventilation (PAV) may enhance leg oxygen (O2) delivery, thereby speeding off-exercise O2 uptake ( O2) kinetics in patients with heart failure with reduced left ventricular ejection fraction (HFrEF). 

Methods: Ten patients (HFrEF= 26±9%) underwent two constant-work rate (70-80% peak) tests to tolerance under PAV or sham ventilation. We assessed post-exercise kinetics of the “primary” component of  O2, vastus lateralis fractional O2 extraction by near-infrared spectroscopy deoxyhemoglobin ([deoxy-Hb+Mb]) and cardiac output (QT) by impedance cardiography.  

Results: PAV significantly accelerated  O2 recovery when compared with sham (τ = 56±22s vs. 77±42s, respectively, p<0.05).  PAV was also associated with a faster decline in ∆[deoxy-Hb+Mb] and QT (τ= 31±19s vs. 42±22s and 39±22s vs. 78±46s, respectively, p<0.05). Faster off-exercise QT with PAV was related to longer exercise duration (r= -0.76; p<0.05).

Conclusion: PAV accelerates the recovery of central hemodynamics and muscle oxygenation in HFrEF. These beneficial effects might prove useful to improve the tolerance to repeated exercise during cardiac rehabilitation.