title: 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.
abstract: 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.
authors.affiliation: Exercise Pathophysiology Research Laboratory, Programa de Pós-Graduação em Ciências da Saúde, Cardiologia e Ciências Cardiovasculares, Universidade Federal do Rio Grande do Sul (UFRGS), Hospital de Clinicas de Porto Alegre (HCPA), Porto Alegre, RS, Brazil.
authors.forename: Fernanda Machado
authors.initials: FM
authors.lastname: Balzan
authors.affiliation: Hospital Santa Casa de Misericórdia de Porto Alegre, Porto Alegre, RS, Brazil.
authors.forename: Régis Chiarelli
authors.initials: RC
authors.lastname: da Silva
authors.affiliation: Biomedical Engineering Division, Universidade Federal do Rio Grande do Sul (UFRGS), Hospital de Clinicas de Porto Alegre (HCPA), Porto Alegre, RS, Brazil.
authors.forename: Danton Pereira
authors.initials: DP
authors.lastname: da Silva
authors.affiliation: Biomedical Engineering Division, Universidade Federal do Rio Grande do Sul (UFRGS), Hospital de Clinicas de Porto Alegre (HCPA), Porto Alegre, RS, Brazil.
authors.forename: Paulo Roberto Stefani
authors.initials: PR
authors.lastname: Sanches
authors.affiliation: Faculdade de Ciências da Saúde Uniritter - Centro Universitário Ritter dos Reis, Porto Alegre, RS, Brazil.
authors.forename: Angela Maria Vicente
authors.initials: AM
authors.lastname: Tavares
authors.affiliation: Exercise Pathophysiology Research Laboratory, Programa de Pós-Graduação em Ciências da Saúde, Cardiologia e Ciências Cardiovasculares, Universidade Federal do Rio Grande do Sul (UFRGS), Hospital de Clinicas de Porto Alegre (HCPA), Porto Alegre, RS, Brazil.
authors.forename: Jorge Pinto
authors.initials: JP
authors.lastname: Ribeiro
authors.affiliation: Respiratory Division, Programa de Pós-Graduação em Ciências Pneumológicas, Universidade Federal do Rio Grande do Sul (UFRGS), Hospital de Clinicas de Porto Alegre (HCPA), Porto Alegre, RS, Brazil.
authors.forename: Danilo Cortozi
authors.initials: DC
authors.lastname: Berton
authors.affiliation: Cardiology Division, Programa de Pós-Graduação em Ciências da Saúde, Cardiologia e Ciências Cardiovasculares, Universidade Federal do Rio Grande do Sul (UFRGS), Hospital de Clinicas de Porto Alegre (HCPA), Porto Alegre, RS, Brazil.
authors.forename: Nadine Oliveira
authors.initials: NO
authors.lastname: Clausell
keywords: Cardiac output; diaphragmatic contraction; venous return