Positive airway pressure levels and pneumothorax: A case-control study in very low birth weight infants

Objectives. Evaluate the incidence of pneumothorax (PTx) and the levels of positive airway pressure (Paw) applied to very low birth weight infants during the first 5 days of life (DOL), after evidence-based protocols using early continuous positive airway pressure (CPAP) and high levels of Paw (CPAP or mean airway pressure) were implemented. Methods. From 2004 to 2007, all infants submitted to assisted ventilation that developed PTx were identified. Controls were matched by birth weight, gestational age, and type of ventilatory support. Paw levels were averaged on a time-weighted basis. A p value <0.05 was considered significant. Results. A total of 25 infants developed PTx (3.8%); 23 during the first 5 DOL. PTx was diagnosed at 14 h of life (1.3-80 h) when 74% were treated with mechanical ventilation. In controls, Paw decreased over time whereas in PTx infants it did not decline until after 80 h. PTx infants had an increase in Paw from 12 h up to 6 h prior to the diagnosis. Conclusion. The rate of PTx was low even after the implementation of the protocols. An association between Paw levels and PTx was observed but until the precise time of onset of a PTx can be determined this should be regarded either as an early signal or as an indicator of more severe lung disease.