Could inspiratory capacity predict lung hyperinflation in patients with obstructive ventilatory impairment?

<bold>Introduction:</bold> Obstructive ventilatory impairments (OVI) are respiratory conditions often associated with air trapping. This study aims to evaluate whether a reduced Inspiratory Capacity (IC) can predict pulmonary hyperinflation in those with OVI. <bold>Methods:</bold> This was a cross-sectional study conducted over a period of 7 months, involving 300 Tunisian patients who underwent full-body plethysmography. The GLI 2012 and 2021 standards were respectively applied to interpret spirometric data and static lung volumes. The diagnosis of OVI was established when the z-score of FEV1/FVC ratio was less than "-1.645". Pulmonary hyperinflation was defined by a z-score of the residual volume (RV) to total lung capacity (TLC) ratio greater than "+1.645". <bold>Results:</bold> Only 43 patients met the inclusion criteria for the study. The median age was 57.5 years [10; 82]. Among the participants, 29 (67%) were male, and 27.9% were classified as obese. Initially, of the 300 patients considered, 29 were identified as having OVI with a reduction in inspiratory capacity (IC) below 80%, which suggests a possible association with pulmonary hyperinflation. These findings were re-evaluated by considering the z-score of the RV/TLC ratio. Among the final 43 patients included in the study, 69.7% exhibited a z-score of the RV/TLC ratio greater than "+1.645," thus confirming the presence of pulmonary hyperinflation. <bold>Conclusion:</bold> "The reduction in IC could potentially be a valuable predictor of pulmonary hyperinflation in patients with obstructive ventilatory impairment. However, more extensive studies involving larger samples are needed to corroborate these findings.