Factors Predicting the Outcome of Noninvasive Ventilation in Acute Respiratory Failure Secondary to Chronic Obstructive Pulmonary Disease Exacerbation

Abstract

Introduction: Non-invasive Mechanical Ventilation (NIV) is a better alternative for treating respiratory failures of any cause compared to invasive ventilation. Various factors influence the outcomes of patients treated with NIV in acute respiratory failure secondary to Chronic Obstructive Pulmonary Disease (COPD). Aim: To determine the possible early predictors and associated factors influencing the outcome of NIV in acute respiratory failure due to COPD patients. Materials and Methods: This was hospital-based observational study undertaken at SRM Medical Hospital and Research Centre in the Respiratory Medicine Department, after obtaining ethical clearance and informed patient consent. All patients with COPD exacerbation were admitted to the respiratory medicine ward. An Arterial Blood Gas (ABG) analysis was carried out, and those patients with type 2 respiratory failure were included in the study. This study included 42 patients with acute respiratory failure secondary to COPD requiring NIV. Data of patient's ABG parameter, heart rate, blood pressure, and respiratory rate baseline values were noted and at an interval of one hour, six hours, and every 24 hours were recorded. The outcome was divided into two categories depending upon whether patients improved or required invasive ventilation. Data were entered in Microsoft Excel datasheet and was analysed using Statistical Package For The Social Sciences (SPSS) 22 version software. Results: Of 42 patients, 30 (71.42%) were treated successfully with NIV, while 12(28.57%) required invasive ventilation and were declared NIV failure (requiring invasive ventilation). Among the patients, it was observed that patients with mean age >60 years, BMI >26.5, baseline pH 78, heart rate >120, respiratory rate >40, co-morbidities and infective exacerbation were requiring invasive ventilation. It was also observed that among the failure category patients treated with conventional Spontaneous and Timed (S/T) mode showed more failure rates than Average Volume Assured Pressure Support (AVAPS) S/T mode. Conclusion: Patients with acute respiratory failure secondary to COPD responds well to NIV. The baseline pH, PaCO2 , HR and Respiratory Rate (RR) before initiation of NIV predicts outcome. Also, age, BMI, associated comorbidities and mode of NIV predicts the outcome.

Keywords

• arterial blood gas
• average volume assured pressure support
• haemodynamic instability