Factors Related to Noninvasive Ventilation Outcomes during an Episode of Hypercapnic Respiratory failure in Chronic Obstructive Pulmonary Disease.

Non invasive ventilation (NIV) plays a vital role in the treatment of an episode of Hypercapnic respiratory failure (HRF) in Chronic obstructive pulmonary disease (COPD) patients. We wanted to investigate the possible effect on NIV outcomes of i) demographic factors, ii) the etiology of an episode of HRF and iii) the overall number and "individual" chronic and acute co-morbidities iv) biochemical parameters in COPD patients ventilated for an episode of HRF. This prospective study of 102(49.29%) COPD patients with HRF were eligible for NIV conducted in Respiratory care unit (RCU) and Intensive care unit (ICU) of National Institute of Diseases of the Chest and Hospital (NIDCH), Dhaka, Bangladesh from July 2016 to December 2017. Among them 70(68.63%) patients were improved and 32(31.37%) were not improved. On the study, some variables were associated with NIV outcome. On gross difference, two sample Z test had been applied in variables - age (p<0.01), mean days hospital stays before introduction of NIV (p<0.0001), APACHE II (Acute Physiological And Chronic Health Evaluation II) (p<0.001), Charlson co-morbidity index (CCI) (p=0.0212), serum albumin (p<0.001), PH (p=0.007), serum potassium (p<0.0001) whereas χ² test had been applied in variables - nutritional status (p<0.01), pneumonia (p=0.0003), dementia (p=0.0004), connective tissue disease (p=0.0094), mild liver disease (p=0.0355), diabetes mellitus with end organ damage (p=0.017), renal disease (p=0.0462), fibrothorax (p=0.0422). Some variables were not associated (p>0.05) with NIV outcome- two sample Z test had been done in variables- smoking status, PaO₂ /FiO₂ (p=0.7235), HCO₃ - (p=0.1552), serum sodium (p=0.0827) whereas χ² test had been done in variables - sex, educational background, congestive heart failure (p=0.06), cardiogenic pulmonary oedema (p=0.6358) and pneumothorax (p=0.06), history of myocardial infarction (p=0.1024), congestive heart failure (p=0.06), peripheral vascular disease (p=0.4636), cerebrovascular disease (p=0.1074), peptic ulcer disease (p=0.06), hemiplegia (p=0.4138) , Diabetes without end organ damage (p=0.1034), tumour without metastasis (p=0.42259), solid tumour with metastasis (p=0.0562), leukaemia (0.1388), lymphoma (p=0.9388), obstructive sleep apnoea (0.9395), bed ridden patients (0.4984), history of pulmonary tuberculosis (p=0.08), kyphoscoliosis (p=0.1388), pneumenectomy (p=0.1388). On logistic regression analysis, eight variables had been shown association with NIV outcome among the seventeen variables which had association with NIV outcome in two sample Z test and χ² tests. Presence of Dementia increased chance of NIV failure 19.32 times, diabetes with end organ damage 10.9375 times and pneumonia 5.3636 times, fibrothorax 3.8077 times, renal disease 2.7273 times. Serum potassium imbalance 1.4615 times and increased serum albumin 1g/dl increased chance of NIV success 1.79 times, PH had also association with NIV outcome. Variables that predict the outcome of NIV are some non modifiable and some modifiable. If special precaution is taken for non modifiable variables and necessary management to correct the abnormalities of modifiable variables, improvements of patient's condition with NIV will be more satisfactory than the present condition.