Risk factors for Pulmonary Interstitial Emphysema (PIE) in Mechanically Ventilated Neonates with Hyaline Membrane Disease

ABSTRACT

PURPOSE: Pulmonary interstitial emphysema (PIE) is a common and serious complication of mechanical ventilation in infants with hyaline membrane disease. This abnormal collection of gases has two basic roentgenographic features; linear and cyst-like radiolucencies. High positive inspiratory pressure was found to be the most significant parameter associated with development of fatal pulmonary interstitial emphysema. Without prompt conservative management such as lowering peak inspiratory pressure, PIE often progress to a pneumothorax with increased mortality. We studied the incidence and risk factors of PIE and associated risk factors which progress to pneumothorax in mechanically ventilated infants with hyaline membrane disease. METHODS: We reviewed retrospectively the charts of infants who had been admitted to the neonatal intensive care unit between Jan. 1990 and Mar. 1995. A hundred and two infants who were diagnosed as hyaline membrane disease and mechanically ventilated were included in the study. Analysis of clinical characteristics and ventilator parameters were made. Chest radiographs were reviewed for hyaline membrane disease, PIE, pneumothorax by a pediatric radiologist without knowledge of their clinical course. RESULTS: 1) We observed PIE in 14 of 102 infants (13.7%) of which 11 infants progressed to develop pneumothorax. 2) Low gestational age, low apgar score and high peak inspiratory pressure were the factors significantly associated with development of PIE. 3) PIE was frequently located bilaterally (52%), distributed on whole lung parenchyme (92%). Sizes of radiolucency were variable including blebs. 4) Early onset PIE and failure to promptly lower peak inspiratory pressure were the associated risk factors for development of pneumothorax. 5) Pneumothorax developed within a mean 7.5 hours after apperance of PIE. Right side pneumothorax was more frequent (67%). Mortality increased to 73% with development of pneumothorax in PIE. CONCLUSIONS: Early diagnosis of PIE and prompt lowering of peak inspiratory pressure should be emphasized to improve the survival and outcome of mechanically ventilated hyaline membrane diasease infants.