• Paulo T Muller and Erlandson F Saraiva.
• Laboratory of Respiratory Pathophysiology (LAFIR), Federal University of Mato Grosso do Sul (UFMS)/Maria Aparecida Pedrossian Hospital (HUMAP), Campo Grande, Mato Grosso do Sul, Brazil.
• Clin Physiol Funct Imaging. 2021 Jan 1; 41 (1): 103-109.

Background/ObjectiveThe current approach to measuring ventilatory (in)efficiency (V'E -V'CO2 slope, nadir and intercept) presents critical drawbacks in the evaluation of COPD subjects, owing mainly to mechanical ventilatory constraints. Thus, we aimed to compare the current approach with a new method we have developed for ventilatory efficiency calculation.MethodsThe new procedure was based on measuring the amount of CO2 cleared by the lungs (V'CO2 , L/min) plotted against a predefined range of increase in minute ventilation (V'E ) (ten-fold increase based on semilog scale) during incremental exercise to symptom-limited maximum tolerance. This value was compared to a hypothetical predicted maximum CO2 output at the predicted maximal voluntary ventilation, defining ventilatory efficiency (ηV'E , %). The results were used to compare 30 subjects with COPD (II-IV Global Initiative for Chronic Obstructive Lung Disease, GOLD) and 10 non-COPD smokers, to establish the best discriminative physiological variable for disease severity through logistic multinomial regression.ResultsThe new approach was more sensitive to progressive deterioration of airway obstruction, resulting in worse ηV'E as lung function worsens throughout the GOLD panel (ηV'E (%), p < .001), when compared with V'E -V'CO2 slope (p = .715) or V'E -V'CO2 nadir (p = .070), besides showing the best model based on the logistic regression approach.ConclusionAlthough requiring more complex calculations compared to the current procedure, the new approach is highly sensitive to true ventilatory/gas-exchange deterioration, even throughout more severe pulmonary lung function in COPD subjects.© 2020 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

13 keywords...

hide…