VAP refers to pneumonia that arises more than Pneumonia has been defined as an acute infection of the pulmonary parenchyma. Pneumonia was defined by ATS/IDSA (2016) criteria clinically as the presence of “new lung infiltrate plus clinical evidence that the infiltrate is of an infectious origin, which include the new onset of fever, purulent sputum, leukocytosis, and decline in oxygenation”.Pneumonia is the eighth leading cause of death and first among infectious causes of death. The mortality rate is as high as 23% for patients admitted to the intensive care unit for severe pneumonia.

The symptoms of pneumonia include fever with chills, cough with expectoration, pleuritic chest pain, malaise, loss of appetite, myalgia. Some patients may have an altered mental status, abdominal pain and other systemic findings. Infiltrates on chest radiograph or computed tomography scan, total and differential leucocyte count, sputum gram stain, sputum culture and sensitivity and blood culture are the investigations which aids to diagnose pneumonia. Procalcitonin and C-Reactive Protein (CRP) are used to differentiate between bacterial and viral pneumonia.

Pneumonia has been classified into the following by American Thoracic Society:

1.Community Acquired Pneumonia (CAP)

2. Hospital Acquired Pneumonia (HAP)

3.Ventilator Associated Pneumonia (VAP) 

48 hours after endotracheal intubation. Ventilator-associated pneumonia (VAP) is one of the most frequent ICU-acquired infections. A data suggests that approximately 10% of patients who required mechanical ventilation were diagnosed with VAP.All-cause mortality associated with VAP ranges from 20% to 50% while attributable mortality is 13%.

The Clinical Pulmonary Infection Score (CPIS) is a tool used to assess the likelihood of ventilator-associated pneumonia (VAP) in mechanically ventilated patients. CPIS score include the following: tracheal secretions, chest x-ray infiltrates, temperature, leukocytes count, P/F ratio. CPIS score of >6 is highly suggestive of ventilator associated pneumonia in the clinical setting.  Modified CPIS score includes microbiological culture also. LUPPIS score also includes Lung Ultrasound in place of chest x-ray and Pentraxin-3 (PTX-3). ATS guidelines recommend noninvasive sampling of respiratory secretions with semi-quantitative cultures for the diagnosis of VAP.

To date there is scarcity of literature regarding the efficacy of endobronchial instillation of colistin in ventilator associated pneumonia patients. Therefore, we plan to conduct this study to evaluate the effect of endobronchial instillation of colistin on outcomes in patients with ventilator associated pneumonia