Ventilator-associated pneumonias in children (I)--diagnostic criteria, etiology and pathogenesis

Ventilator-associated pneumonias have been estimated to be the second most common nosocomial infections among children treated in intensive care units. They occur in mechanically ventilated patients through intubation tube or tracheostomy, the inflammation usually involving the lung parenchyma. The ventilator-associated pneumonia is associated with a longer antibiotic treatment, greater duration of mechanical ventilation (MV) and higher mortality rates in children. The condition is also associated with a higher cost of the treatment. This paper reviews and comments in detail the criteria formulated by the National Nosocomial Infection Surveillance (NNSI) and the Centers for Disease Control and Prevention (CDC) for diagnosis of ventilator-associated pneumonias in children. The disease etiology is associated with the typical causes of nosocomial infections in this age: P. aeruginosa, E. coli and K. pneumoniae. The pathogenesis of the condition is inadequately studied but the aspiration of gastric contents and immune deficiency are proven risk factors. Two mechanisms have a major role in the development of the disease--micro-aspiration of gastric contents and colonization of the lower airways with pathogens.