A Clinico-Bacteriological Study and Effect of Stress Ulcer Prophylaxis on Occurrence of Ventilator Associated Pneumonia: a Randomized Prospective Study

Study population: Fifty patients of either sex admitted to Medical Intensive Care Unit and Intensive Care Unit of Anaesthesiology department of Maulana Azad Medical College and Lok Nayak Hospital, New Delhi( a 2000 bedded, tertiary care centre), fulfilling the criteria were enrolled and prospectively followed up until one week after discharge from intensive care unit or till death.

Methodology: Ventilator associated pneumonia was diagnosed when new and persistent pulmonary infiltrates (not otherwise explained) appeared on chest radiograph after 48 hours of ventilation and any two of the following three criteria were fulfilled:

1. Temperature of more than 38oC or less than 35oC.
2. Leukocytosis ≥16,000 or leukopenia ≤ 3,000.
3. Purulent endotracheal aspirate and/or positive endotracheal aspirate culture. Protocol of study: All patients were ventilated by orotracheal or tracheostomy tube, which was changed only if, blocked or displaced. Patients were ventilated in supine position with frequent changing to right lateral and left lateral positions and nasogastric tube was put in all patients. No prophylactic topical oropharyngeal antibiotic and selective gut decontamination was done in any of the patients. Base line complete blood count was done in all patients at time of intubation. Subsequent counts were done when pneumonia was suspected by onset of fever, new chest signs, worsening of ventilatory requirement and radiologically new infiltrates. Baseline chest X-ray and endotracheal aspirate culture was done at intubation and at 48 hours of ventilation and subsequently done at suspicion of pneumonia or any other pulmonary complications, 48 hours after pneumonia has been detected, routinely once a week if no pneumonia is detected. Nasogastric aspirate culture was done on 3rd and 7th day of intubation and every week thereafter. Gastric colonization was diagnosed if more than 103 colony-forming units/ml were found. Clinical examination for pneumonia and chest radiographs after one week of extubation were done on follow up.

Method of collection of samples: Endotracheal aspirate was collected with mucus trap under all aseptic precautions. Nasogastric (NG) aspirate was collected from indwelling NG tubes. After removing the initial 5 ml, the next 10 ml of fluid in the tube was aspirated into a sterile syringe and immediately transported to the laboratory for processing.

Culture method: A Semi quantitative culture of the endotracheal aspirate and nasogastric aspirate was done [6]. A Measured amount of aspirate was plated on blood agar and Mac-Conkey medium and a colony count was done after incubation. A sample of blood was collected in glucose broth and after overnight incubation, subcultures were done on blood agar and Mac-Conkey agar. Colony characteristics were observed and identification was done in accordance with standard recommendations. Susceptibility of the organisms isolated from endotracheal aspirate was done by disc diffusion technique employing the Stokes method.