A Study of Indications and Outcome of Non-Invasive Ventilation in Respiratory Care Unit of a Tertiary Care Hospital in Eastern India

Abstract

Introduction: Patients with Acute Respiratory Failure (ARF) can be ventilated noninvasively through Bi-Level Positive Pressure Ventilation (Bi-PAP). The proper timing, indications and outcome of Non-invasive Ventilation (NIV) have been evaluated worldwide by many investigators. Optimum selection of patients leads to better outcome reducing need for invasive ventilation; while the reverse can cause inappropriate delay in intubation leading to clinical deterioration, increased morbidity and mortality. Aim: To evaluate the indications and outcome, with relevant factors in all patients requiring NIV in Respiratory Care Unit (RCU) of a teaching hospital. Materials and Methods: This was a hospital-based observational study conducted from April 2016 to March 2017. After ethical approval, all patients who were put on NIV in RCU of the institution during the period of one year were enlisted. Evaluation by history, detailed clinical examination and necessary investigations including blood count, biochemistry, Arterial Blood Gas (ABG) analysis, oxymetry, microbiological investigations, imaging of thorax etc., was done. Examination and investigations were periodically repeated as necessary. Pre-fixed NIV protocol and end point definitions were followed. Descriptive statistics done using Mean and Standard Deviation (SD). Mann-Whitney U test was done for comparing quantitative data. Chi-square test or Fisher’s-exact test was used to compare categorical data. Results: Most common age group for Respiratory Failure (RF) was 41 to 60 years, (mean 56.5±11.6), with a male predominance (M:F=1.4:1). The most common underlying disease leading to RF and requiring NIV support was Acute Exacerbation of Chronic Obstructive Pulmonary Disorder (COPD) (n=31) in Type 2 and pneumonia (n=11) in Type 1 RF. Hypertension (25%) and diabetes mellitus (20%) were common co-morbidities. Favourable outcome was seen in 68.33% patients an average hospital stay of 15 days. The baseline APACHE-II (Acute Physiology and Chronic Health Evaluation) score (p≤0.0001) and Partial Pressure of Oxygen(PaO2)/ Fraction of Inspired Oxygen (FiO2) at 1st hour of NIV (p=0.0054) have significant predictive value the outcome. Reasons for shifting to IMV were: non-improvement of ABG (37.93%), worsening of dyspnoea (24.14%) and haemodynamic instability (20.7%). Average time gap from initiation of NIV to mechanical ventilation in failure cases was 8.03 hours in Type 2 RF and 5.78 hours in Type 1 RF. Fatality rate in Type 2 RF (23.68%) was much less than in Type 1 RF (45.45%). Conclusion: This study strengthens the fact that efficient utilisation of NIV therapy in properly selected patients of acute RF can lead to reduced need for IMV, thus reducing the cost and complications. Disease severity at admission (APACHE-II score), non-improvement of ABG parameters in 1st and 4th hour of NIV initiation, PaO2/FiO2 ratio, development of haemodynamic instability and deteriorating level of consciousness, all play pivotal roles in the outcome assessment.