Effects of diaphragmatic contraction on lower limb venous return and central hemodynamic parameters contrasting healthy subjects versus heart failure patients at rest and during exercise

• Published in: Physiological reports Vol. 2; no. 12; pp. e12216 - n/a
• Main Authors: Balzan, Fernanda Machado, Silva, Régis Chiarelli, Silva, Danton Pereira, Sanches, Paulo Roberto Stefani, Tavares, Angela Maria Vicente, Ribeiro, Jorge Pinto, Berton, Danilo Cortozi, Clausell, Nadine Oliveira
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01.12.2014; Wiley Periodicals, Inc
• Subjects: Abdomen; Blood flow; Cardiac output; Compression therapy; Congestive heart failure; Contraction; diaphragmatic contraction; Doppler effect; Dyspnea; Esophagus; Femur; Heart failure; Hemodynamics; Knee; Original Research; Physiology; Respiration; Ultrasound; Veins & arteries; venous return; diaphragmatic contraction; venous return; Cardiac output
• ISSN: 2051-817X; 2051-817X
• DOI: 10.14814/phy2.12216

The main objective was to assess the effects of abdominal breathing (AB) versus subject's own breathing on femoral venous blood flow (Qfv) and their repercussions on central hemodynamics at rest and during exercise contrasting healthy subjects versus heart failure (HF) patients. We measured esophageal and gastric pressure (PGA), Qfv and parameters of central hemodynamics in eight healthy subjects and nine HF patients, under four conditions: subject's own breathing and AB (∆PGA ≥ 6 cmH2O) at rest and during knee extension exercises (15% of 1 repetition maximum) until exhaustion. Qfv and parameters of central hemodynamics [stroke volume (SV), cardiac output (CO)] were measured using Doppler ultrasound and impedance cardiography, respectively. At rest, healthy subjects Qfv, SV, and CO were higher during AB than subject's breathing (0.11 ± 0.02 vs. 0.06 ± 0.00 L·min−1, 58.7 ± 3.4 vs. 50.1 ± 4.1 mL and 4.4 ± 0.2 vs. 3.8 ± 0.1 L·min−1, respectively, P ≤ 0.05). ∆SV correlated with ∆PGA during AB (r = 0.89, P ≤ 0.05). This same pattern of findings induced by AB was observed during exercise (SV: 71.1 ± 4.1 vs. 65.5 ± 4.1 mL and CO: 6.3 ± 0.4 vs. 5.2 ± 0.4 L·min−1; P ≤ 0.05); however, Qfv did not reach statistical significance. The HF group tended to increase their Qfv during AB (0.09 ± 0.01 vs. 0.07 ± 0.03 L·min−1, P = 0.09). On the other hand, unlike the healthy subjects, AB did not improve SV or CO neither at rest nor during exercise (P > 0.05). In healthy subjects, abdominal pump modulated venous return improved SV and CO at rest and during exercise. In HF patients, with elevated right atrial and vena caval system pressures, these findings were not observed. e12216 Circulatory function of the diaphragm produces an increase in circulatory output. Moreover, the peripheral muscle contraction produces greater venous blood return due to increased blood expulsion. In this study, we focused on the effects of diaphragm contraction at rest and during knee extension exercise on venous return and central hemodynamics in healthy subjects and heart failure patients. These results help us understand the mechanisms of abdominal pump modulation on venous return in healthy subjects and under conditions of elevated pressure of the right atrium and the vena cava.