Comparative Analysis of Peak Inspiratory Flow Rate at Discharge and Three-month Follow-up in Severe Acute Exacerbation of COPD Patients using Metered Dose Inhalers versus Dry Powder Inhalers: A Prospective Observational Study

Abstract

Introduction: Patients discharged following hospitalisation for Acute Exacerbation of Chronic Obstructive Pulmonary Disease (AECOPD) are prescribed Metered Dose Inhalers (MDI), Dry Powder Inhalers (DPI), or nebulisers. Drug dispersion from the inhaler and deposition in the lung depends on Peak Inspiratory Flow Rate (PIFR) among other factors. A low PIFR results in suboptimal drug delivery and is a risk factor for readmission. Aim: To estimate PIFR at discharge following AECOPD, assess the type of inhalers prescribed at discharge, and estimate the mean change in PIFR at three months follow-up in patients using MDI and DPI. Materials and Methods: A prospective observational study was conducted at a tertiary care hospital, Goa Medical College, Goa, India on 138 patients over 15 months from November 2018 to February 2020. A sample size of 138 was calculated, and the study duration was 15 months. Patients admitted with AECOPD were enrolled in the study after obtaining informed consent. At discharge, baseline characteristics and co-morbidities were recorded, and PIFR was measured using an in-check dial peak inspiratory flow meter without resistance. Inhalers prescribed by the treating physician were verified and checked for errors. PIFR was measured at three months of follow-up. Optimal PIFR was defined as PIFR of ≥60 L/min. Statistical analysis was performed using the Statistical Package for Social Science Programs (SPSS) version 24.0 (IBM Corp, SPSS Inc, Chicago, IL). A paired t-test assessed the change in PIFR at discharge and three months follow-up, and Pearson’s correlation test was used to assess the correlation between continuous variables. Results: Total 138 were enrolled with a mean age of 69.8±7.5 years, 87 (63%) were males. The mean PIFR at discharge was 58.9±24.7 L/min. 85 (61.6%) had suboptimal PIFR and were older {71.9±7.8 versus 66.3±5.6, p-value=0.01}. A total of 59 (69.4%) with suboptimal PIFR received MDI. At three months, the suboptimal PIFR group receiving MDI showed a mean change in PIFR of 18.6±7.7, p-value<0.001 while with DPI mean change was -3.8±6.3, p-value=0.005. Conclusion: 61.6% had suboptimal PIFR at discharge following hospitalisation with AECOPD. Patients with suboptimal PIFR receiving MDI showed improvement in PIFR at three months, while those with suboptimal PIFR using DPI showed significant deterioration. Identifying patients with suboptimal PIFR will aid appropriate prescription of inhaler devices.