Study of Ventilator Associated Pneumonia in Neonatal Intensive Care Unit: characteristics, risk factors and outcome

Abstract

Ventilator Associated Pneumonia (VAP), the nosocomial pneumonia developing in mechanically ventilated patients after 48 hours of mechanical ventilation, is the second most common nosocomial infection.
Therefore, there is a vital need to study the etiology and risk factors associated with VAP in neonates. Neonates admitted to neonatal intensive care unit (NICU), over a period of 1 year and who required mechanical ventilation for more than 48 hours were enrolled consecutively into the study. Diagnosis of VAP was made by the guidelines given by National Nosocomial infection Surveillance System (NNIS, 1996). Semi-quantitative assay of endotracheal aspirate was used for microbiological diagnoses of VAP. 105CFU/ml was taken as the cut off between evidence of pathological infection and colonization. The risk factors such as birth weight, prematurity (gestational age < 37 weeks), duration of mechanical ventilation, number of reintubations, length of hospital stay, primary diagnosis of neonate, postnatal age and small for gestational age (SGA) were studied for the development of VAP. Risk factors found significant on bivariate analysis were subjected to multiple regression analysis to determine the most important predictors of VAP. The study group comprised of 98 neonates out of which, 30 neonates developed VAP (30.6%). VAP rates were 37.2 per 1000 days of mechanical ventilation. Most common bacterial isolated from endotracheal aspirate of VAP patients was Klebsiella spp (32.8%), E.coli (23.2%) and Acinetobacter (17.8%) being the other two common organisms. Very low birth weight (<1500 grams), prematurity (gestational age < 37 week), duration of
mechanical ventilation, number of reintubations and length of NICU stay were significantly associated with VAP in bivariate analysis. Multiple regression analysis revealed that duration of mechanical ventilation (OR 1.10, 95% CI 1.02, 1.21; P = 0.021) and very low birth weight (OR 3.88, 95% CI 1.05, 14.34; P = 0.042) were two single independent and statistically significant risk factors for predicting VAP. VAP developed in nearly one third of intubated neonates having gram negative organisms as predominant etiological agent.

KEY WORDS: Neonates; Nosocomial infection; Outcome; Risk factors;
Ventilator associated pneumonia