Orthopnea and inspiratory effort in chronic heart failure patients

Stefano Nava, M. Teresa Larovere, F. Fanfulla, P. Navalesi, M. Delmastro, A. Mortara

Risultato della ricerca: Contributo su rivistaArticolo in rivistapeer review

Abstract

Study objective: Orthopnea is a typical feature of patients with chronic heart failure (CHF), the factors contributing to it are not completely understood. We investigated changes in dyspnea and other respiratory variables, induced by altering posture (from sitting to supine) in II CHF patients (NYHA classes II-IV) and 10 control subjects. Methods and Results: We measured dyspnea (Borg scale), the diaphragm pressure time product per minute (PTPdi/m, index of metabolic consumption), and mechanical properties of the lung (lung compliance (C,L) and resistances (R,L). CHF patients also underwent a trial of non-invasive mechanical ventilation (NIMV) inthe supine position in order to ascertain whether unloading the inspiratory muscles could somehow relieve dyspnea. While sitting the PTPdi/min was significantly higher in CHF patients than in controls (181±54 cm H2O × s/min vs. 96±32; P<0.05). Assuming a supine position caused no major changes in controls, whereas CHF patients showed a significant worsening in dyspnea, a rise in PTPdi/min (243±97 p<0.01) and R,L (4.7±1.2 cm H2O/L × s sitting vs. 79±2.5 supine; P<0.01) and a decrease in C,L (0.08±0.02 L/cm H2O sitting vs. 0.07+0.01 supine; P<0.05). Applying NIMV to supine CHF patients significantly reduced the PTPdi/min to 81±42 (P<0.001). Changes in dyspnea, produced by varying position or applying NIMV, were significantly correlated with PTPdi/min (r=0.80, P<0.005 and r=0.58, P<0.01, respectively). Conclusions: CHF patients had a higher PTPdi/min than controls when sitting, and assuming a supine position induced severe dyspnea, a large rise in R,L, and a reduction in C,L so that PTPdi/min increased further. Orthopnea was strongly correlated with the increased diaphragmatic effort.

Lingua originaleInglese
pagine (da-a)647-653
Numero di pagine7
RivistaRespiratory Medicine
Volume97
Numero di pubblicazione6
DOI
Stato di pubblicazionePubblicato - 1 giu 2003
Pubblicato esternamente

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