INTRODUCTION: Non-Invasive Ventilation (NIV) is a crucial therapy for managing acute exacerbations of Chronic Obstructive Pulmonary Disease (COPD) with hypercapnic respiratory failure. Research has shown that NIV can decrease the rate of endotracheal intubation, length of hospital and Intensive Care Unit stays, and mortality. There are three main strategies for weaning patients off NIV: gradual reduction of NIV duration, gradual reduction of NIV pressure support, and immediate cessation of NIV.
AIM: To compare the rate of successful withdrawal of COPD patients with acute hypercapnic respiratory failure, one group will use a stepwise reduction of duration of NIV, while the other group will use a stepwise reduction of pressure support.
MATERIALS AND METHODS: This study was a prospective observational study conducted at the Department of Pulmonary Medicine, Institute of Chest Diseases, Government Medical College, Kozhikode, over a period of 15 months. The study population consisted of all COPD patients admitted to the Pulmonary Medicine ward or ICU with acute hypercapnic respiratory failure who were managed with non-invasive ventilation (NIV) without the need for invasive mechanical ventilation. Exclusions included patients requiring NIV for respiratory diseases other than COPD, those with significant comorbidities like acute left ventricular failure or fluid overload states as in chronic kidney disease, COVID-19 positive patients, patients on home NIV, patients who needed intubation early in treatment, and patients unwilling to participate in the study. The sample size was 140. Initial NIV settings and other management decisions prior to enrolment in the study were made by the treating physician according to standard protocols. Once weaning criteria were met (i.e., arterial pH > 7.35, SpO2 ≥ 90% at an FiO2 ≤ 50%, respiratory rate ≤ 25 breaths per minute, heart rate ≤ 120 beats per minute, systolic BP > 90 mm Hg, and no signs of respiratory distress), patients were assigned to either group 1 or group 2 by purposive sampling. Group 1: stepwise reduction of duration of NIV use, with a reduction to 16 h per day on day 1 of enrolment, 12 h on day 2 (including 6-8 h of nocturnal NIV), 6-8 h on day 3, and NIV withdrawal on day 4. Group 2: stepwise reduction of pressure support, with pressure support reduced by 2-4 cm every 4-6 h until Inspiratory Positive Airway Pressure is < 8 cm H2O and Expiratory Positive Airway Pressure is < 4 cm H2O, followed by NIV withdrawal. The clinical outcome was classified as either improved or weaning failure. Improved was defined as an objective or subjective sense of improvement. Weaning failure was defined as the presence of any of the following: respiratory rate ≥ 25/minute or increase of ≥ 50% from baseline, heart rate ≥ 140/minute or increase of ≥ 20% from baseline, SpO2 ≤ 90% on FiO2 ≥ 50%, arterial pH ≤ 7.35, or respiratory distress. Data was collected using a pro forma that included demographic details, smoking status, GOLD COPD category, comorbidities, and vital signs. ABG parameters, NIV settings at the time of hospital admission, at the time of study enrolment, and 48 h after weaning were also recorded. Independent sample t-test was used to test the statistical significance of the difference between means of variables between the two groups. Pearson Chi square test and Fisher's exact test were used to compare categorical variables between the groups. A p-value of < 0.05 was considered statistically significant.
RESULTS: NIV was successfully withdrawn in 56/70 (80%) and 50/70 (71.4%) patients in Groups 1 and 2, respectively. This difference was not statistically significant. The length of hospital stay was longer in the stepwise reduction of duration group (Group 1), but this was not statistically significant.
CONCLUSION: On comparison of two methods of NIV withdrawal, it was found that neither method is superior to the other in terms of weaning failure, intubation rates, and average length of hospital stay.