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Background-Dyspnea and fatigue are the main causes of exercise limitation in chronic heart failure (CHF) patients, whose peak inspiratory (Pi max ) and expiratory pressures (Pe max ) are often reduced. The aim of this study was to examine the relationship between respiratory muscle performance and oxygen kinetics. Methods and Results-A total of 55 patients (NYHA class I to III) and 11 healthy subjects underwent cardiopulmonary exercise tests (CPET) on a treadmill. In 45 of the 55 patients (group I) and in healthy subjects (group II), pulmonary function tests, Pi max , and Pe max were measured before and 10 minutes after exercise, and oxygen kinetics were monitored throughout and during early recovery from CPET. The first degree slope of oxygen consumption (V O 2 ) decline during early recovery (V O 2 /t-slope) and V O 2 half-time (T 1/2 ) were calculated. In 10 of the 55 CHF patients (group III), the measurements of Pi max were repeated 2, 5, and 10 minutes after CPET. A Ͼ10% reduction in Pi max after CPET (subgroup IA) was measured in 11 of 45 patients. In contrast, 34 of 45 CHF patients (subgroup IB) and all control subjects (group II) had Pi max Ͼ90% of baseline value after CPET. Subgroup IA patients had significantly lower peak V O 2 (13.5Ϯ2.1 versus 17.8Ϯ5.6 mL ⅐ kg Ϫ1 ⅐ min Ϫ1 ; PϽ0.001), lower anaerobic thresholds (10.1Ϯ2.4 versus 13.6Ϯ4.6 mL ⅐ kg Ϫ1 ⅐ min

The purpose of this study was to determine the role of changes in the parameters of venous return on the homeostatic adaption to the application of PEEP. We studied 13 dogs anesthetized with alpha-chloralose, intubated, and ventilated. We measured central venous pressure (CVP), arterial pressure (Pao) and cardiac output by thermal dilution. The cardiac output was transiently stopped by inflating a balloon in the right atrium, and the subsequent plateau in the CVP was used to obtain mean circulatory filling pressure (MCFP). Total blood volume was measured with Evans blue. To measure vascular capacitance and compliance, we rapidly infused 4 ml/kg or 8 ml/kg of blood and repeated the MCFP measurement. The same volume was withdrawn after the measurement. The volume and MCFP were used to construct pressure-volume (P-V) lines, and the unstressed volume was calculated by extrapolating the P-V to zero pressure. The P-V appeared linear in the range studied. PEEP produced a left shift of the curves and, thus, a decrease in unstressed volume. The shift with 20 cm H2O of PEEP was greater than with 10 cm H2O of PEEP. The rise in MCFP matched the rise in CVP so that the pressure gradient for venous return did not change. However, there was also an increase in the resistance to venous return, which resulted in a lower cardiac output than expected for the rise in MCFP. In conclusion, homeostatic adjustments to PEEP included a decrease in vascular capacitance, which is partially offset by a rise in the resistance to venous return.

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Background Vascular endothelial dysfunction is an underlying pathophysiological feature of chronic heart failure (CHF). Endothelial progenitor cells (EPCs) are also impaired. The purpose of the study was to assess the effect of a cardiac rehabilitation (CR) program on the increase of EPCs at rest and on the acute response after maximal exercise in patients with CHF and investigate whether there were differences between two exercise training protocols and patients of NYHA II and III classes. Methods Forty-four patients with stable CHF enrolled in a 36-session CR program and were randomized in one training protocol; either high-intensity interval training (HIIT) or HIIT combined with muscle strength (COM). All patients underwent maximum cardiopulmonary exercise testing (CPET) before and after the CR program and venous blood was drawn before and after each CPET. Five endothelial cellular populations, expressed as cells/10 6 enucleated cells, were quantified by flow cytometry. Results An increase in all endothelial cellular populations at rest was observed after the CR program (p < 0.01). The acute response after maximum exercise increased in 4 out of 5 endothelial cellular populations after rehabilitation. Although there was increase in EPCs at rest and the acute response after rehabilitation in each exercise training group and each NYHA class, there were no differences between HIIT and COM groups or NYHA II and NYHA III classes (p > 0.05). Conclusions A 36-session CR program increases the acute response after maximum CPET and stimulates the long-term mobilization of EPCs at rest in patients with CHF. These benefits seem to be similar between HIIT and COM exercise training protocols and between patients of different functional classes.

Ž .Ž . Background: Oxygen O uptake at peak exercise VO peak is an objective measurement of functional capacity in patients 2 2 Ž . with chronic heart failure CHF . The significance of recovery O kinetics parameters in predicting exercise capacity, and the 2 Ž parameters of submaximal exercise testing have not been thoroughly examined. Methods and results: Thirty-six patients mean . w x w x w x age s 48 " 14 years with CHF and New York Heart Association functional class I 12 , II 17 , or III 7 , and eight healthy Ž . Ž . volunteers mean age s 39 " 13 years were studied with maximal and submaximal cardiopulmonary exercise testing CPET .Ž . The first degree slope of O uptake decay during early recovery from maximal VO rt-slope , and submaximal exercise . Ž . Ž . P-0.001 , with the VO peak r s 0.87, P -0.001 and with T VO after maximal exercise r sy0.62, P -0.001 .