A Systematic Review of Methods Used to Determine the Work of Breathing during Exercise.

Introduction: Measurement of the work of breathing (Wb) during exercise provides useful insights into the energetics and mechanics of the respiratory muscles across a wide range of minute ventilations. The methods and analytical procedures used to calculate the Wb during exercise have yet to be critically appraised in the literature. Purpose: The aim of this systematic review was to evaluate the quality of methods used to measure the Wb during exercise in the available literature. Methods: We conducted an extensive search of three databases for studies that measured the Wb during exercise in adult humans. Data were extracted on participant characteristics, flow/volume and pressure devices, esophageal pressure (Poes) catheters, and methods of Wb analysis. Results: A total of 120 articles were included. Flow/volume sensors used were primarily pneumotachographs (n = 85, 70.8%), whereas the most common pressure transducer was of the variable reluctance type (n = 63, 52.5%). Esophageal pressure was frequently obtained via balloon-tipped catheters (n = 114, 95.0%). Few studies mentioned calibration, frequency responses, and dynamic compensation of their measurement devices. The most popular method of measuring the Wb was pressure-volume integration (n = 51, 42.5%), followed by the modified Campbell (n = 28, 23.3%) and Dean & Visscher diagrams (n = 26, 21.7%). Over one-third of studies did not report the methods used to process their pressure--volume data, and the majority (60.8%) of studies used the incorrect Wb units and/or failed to discuss the limitations of their Wb measurements. Conclusions: The findings of this systematic review highlight the need for the development of a standardized approach for measuring Wb, which is informative, practical, and accessible for future researchers. [ABSTRACT FROM AUTHOR]