Evaluation of pneumothorax risk factors in mechanically ventilated neonates admitted to neonatal intensive care unit

Pneumothorax is the most common pulmonary air leak syndrome which occurs more frequently in the neonatal period than any other time of life. Mechanical ventilation with positive pressure is one of the most common causes of this condition. The aim of this study was to evaluate pneumothorax risk factors in mechanically ventilated neonates admitted to neonatal intensive care unit (NICU) of Besat Hospital in Sanandaj. This was a nested case-control study. Case group were neonates under ventilation with pneumothorax admitted to NICU between April 2012 and March 2013. Control group included neonates under ventilation without pneumothorax whose admission times followed in the immediate chronology to the case group. 31 cases and 62 controls were selected. Data collection was performed by use of medical records and ventilator memory in the last 24 hours. The data were introduced into SPSS software. Analysis of qualitative variables was performed by chi-squared and Fisher test. We used Mann Whitney U test for analysis of quantitative variables and logistic regression in order to control confounders. 61. 3% of newborns with pneumothorax were male and 38. 7% female. 61. 3% of these neonates were born by Cesarean section and 38. 7% by vaginal delivery. Their mean gestational age was 32 weeks and the mean birth weight was 1819 g. 74% of cases had pneumothorax in the right side، 13% left side and 13% bilaterally. Hyaline membrane disease (HMD) was the most common underlying disease (74. 2%) in the newborns with pneumothorax. 38% of neonates under pressure controlled ventilation developed pneumothorax compared to 7. 1% of neonates under synchronized intermittent mandatory ventilation (SIMV)، which showed a significant difference (p=0. 03). Ventilator parameters associated with higher risk of pneumothorax were more episodes of ventilator adjustments (P<0. 001)، high peak inspiratory pressure (p<0. 001)، high positive end expiratory pressure (p=0. 029) and high mean airway pressure (p<0. 001). In general pneumothorax risk factors in mechanically ventilated neonates in our investigation were similar to those of other studies. Our findings indicated that pressure controlled ventilation more episodes of ventilator adjustments، increased peak inspiratory pressure، positive end expiratory pressure and mean airway pressure are major pneumothorax risk factors in the mechanically ventilated newborns. To prevent pneumothorax، it is necessary to avoid frequent changes of ventilator adjustments and decrease in the above mentioned parameters to the levels enough to supply lung oxygenation.