Rationale: During exercise, heart failure patients (HF) show an out-of-proportion ventilation increase, which in patients with COPD is blunted. When HF and COPD coexist, the ventilatory response to exercise is unpredictable. Objectives: We evaluated a human model of respiratory impairment in 10 COPD-free HF patients and in 10 healthy subjects, tested with a progressive workload exercise with different added dead space. We hypothesized that increased serial dead space upshifts the VE vs. VCO2 relationship and that the VE-axis intercept might be an index of dead space ventilation. Measurements: All participants performed a cardiopulmonary exercise test with 0, 250 and 500 mL of additional dead space. Since DS does not contribute to gas exchange, ventilation relative to dead space is ventilation at VCO2 = 0, i.e. VE-axis intercept. We compared dead space volume, estimated dividing VE-axis intercept by the intercept on respiratory rate axis of the respiratory rate vs. VCO2 relationship with standard method measured DS. Main results: In HF, adding dead space increased VE-axis intercept (+0 mL = 4.98±1.63 L; +250 mL = 9.69±2.91 L; +500 mL = 13.26±3.18 L; p<0.001) and upshifted the VE vs.VCO2 relationship, with a minor slope rise (+0 mL= 27±4 L; +250 = 28±5; +500 = 29±4; p<0.05). In healthy, adding dead space increased VE-axis intercept (+0 mL = 4.9±1.4 L; +250 = 9.3±2.4; +500 = 13.1±3.04; p<0.001) without slope changes. Measured and estimated dead space volumes were similar both in HF and healthy subjects. Conclusions: VE-axis intercept is related to dead space ventilation and dead space volume can be non-invasively estimated.
A non invasive estimate of dead space ventilation from exercise measurements / P. Gargiulo, A. Apostolo, P. Perrone-Filardi, S. Sciomer, P. Palange, P. Agostoni. - In: PLOS ONE. - ISSN 1932-6203. - 9:1(2014), pp. e87395.1-e87395.9.
|Titolo:||A non invasive estimate of dead space ventilation from exercise measurements|
AGOSTONI, PIERGIUSEPPE (Ultimo)
|Settore Scientifico Disciplinare:||Settore MED/11 - Malattie dell'Apparato Cardiovascolare|
|Data di pubblicazione:||2014|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1371/journal.pone.0087395|
|Appare nelle tipologie:||01 - Articolo su periodico|
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