Effect of increasing levels of pressure support (PS) with NIV on diaphragmatic function asessed using ultrasound and to identify indicators of NIV failure in patients of AECOPD with type 2 respiratory failure - Pilot study

Abstract

Introduction: US(Ultrasonography) of Diaphragm may be considered as a poor-man9s esophageal catheter. There is a good corelation between diaphragm function assessed by esophageal catheter and US indices. Diaphragm function assessment via US may help predict response of patients to PS via NIV. We aim to study the effect of increasing PS via NIV on US indices, and to identify indicators of NIV failure. Methods: Prospective, observational study. Patients of AECOPD presenting to emergency room with acute dyspnea were screened and 12 patients with type 2 respiratory failure were included in study. Patients were evaluated and managed according to GOLD guidelines. US Diaphragm done on right side using Liver as acoustic window according to standard protocol. Excursion and thickening fraction noted at baseline and following increasing levels of PS. Differences in US indices compared between those who improved on NIV to those who failed NIV. Results: A marked reduction in the diaphragmatic thickening fraction was noted with increasing levels of PS in ten patients who improved on NIV. There was minimal/no reduction in thickening fraction in two patients who failed NIV. There was no corelation between increasing levels of PS via NIV on diaphragmatic excursion. There was no effect of CPAP on either diaphragmatic excursion or thickening fraction. These changes in US findings preceded evaluation by ABG parameters. Conclusion: US diaphragm is a rapid, repeatable, painless, non-invasive bedside tool which may be useful in predicting NIV failure early compared to ABG parameters in AECOPD with type 2 respiratory failure.