Mechanical ventilatory constraints during incremental exercise in healthy and cystic fibrosis children

Abstract

The hypothesis of this study was based on the assumption that mild cystic fibrosis could induce more frequent and more severe mechanical ventilatory constraints due to pulmonary impairment and breathing pattern disturbances. But, this study did not succeed to highlight an effect of mild cystic fibrosis on the mechanical ventilatory constraints (expFL and dynamic hyperinflation) that occur during an incremental exercise. This absence of effect could be due to the absence of an impact of the disease on spirometric data, breathing pattern regulation during exercise and breathing strategy.

A Systematic Approach to Interpreting the Cardiopulmonary Exercise Test in Pediatrics

“…For instance, a child with obstructive pulmonary disease can be expected to have a reduced ventilatory capacity but may or may not have a ventilatory limitation. A ventilatory limitation is traditionally defined by a limited (<20%) ventilatory reserve (VR) during exercise (11). The VR is calculated as VR = 1 -(VE peak /MVV), where VE peak is the maximal volume of air exhaled per minute at peak exercise (MVV = FEV 1 × 35 in children) (11).…”

“…A ventilatory limitation is traditionally defined by a limited (<20%) ventilatory reserve (VR) during exercise (11). The VR is calculated as VR = 1 -(VE peak /MVV), where VE peak is the maximal volume of air exhaled per minute at peak exercise (MVV = FEV 1 × 35 in children) (11). Healthy children have a VR of at least 11 L/min or 20% to 40% of their MVV.…”

“…In early obstructive lung disease (higher residual volume or residual volume to total lung capacity ratio), for example, CPET responses may be normal, but exercise flow-volume loops can demonstrate expiratory flow limitation. Expiratory flow limitation corresponds to the part of the tidal flow-volume loop that meets or exceeds the expiratory boundary of the maximal flow-volume loop and is expressed as a percentage of the tidal volume (11). Post-CPET spirometry can also be helpful to identify postexercise bronchospasm in children who have exercise-induced bronchoconstriction and/or occult asthma and/or who are receiving inadequate asthma medication.…”

Cardiopulmonary Exercise Testing in Pediatrics

“…dynamic hyperinflation, and/or the retention of arterial carbon dioxide. In children, MVV can be estimated by multiplying FEV 1 by 35 (31). It is possible that a ventilatory limitation restricting maximal exercise capacity only exists in children and adolescents with a moderately-to-severely reduced lung function (predicted FEV 1 below 65%) (15).…”

2014 year in review: Cystic fibrosis

“…In contrast, vertical jump did not correlate with lung function. Comparison of children with mild CF to controls did not reveal differences in mechanical ventilatory constraints, defined by expiratory flow limitation and dynamic hyperinflation, during incremental exercise . A validated equation to estimate VO 2 peak using work rate and gender demonstrated reasonable positive and negative predictive values .…”