[Comparative study of diagnostic value of gastric aspirate shakes test and lamellar body count for prediction of lung maturity in premature neonates]

Respiratory distress syndrome due to lack of enough surfactant in fetal lung tissue is a common cause of neonatal mortality. There are several laboratory methods to predict the amount of fetal lung surfactant. The purpose of this study was to compare lamellar body count test [Quantitative test] and gastric aspirate shake test [Qualitative test] for prediction of the amount of pulmonary surfactant in premature neonates. This descriptive- analytic study was performed between August 2012 and January 2013 for 6 months and included 150 premature infants with gestational age of less than 34 weeks, born in Imam Reza [AS] Hospital, in Kermanshah. In this study, both gastric aspirate shake test and lamellar body count test were performed for all infants simultaneously. Using nasogastric tube we aspirated at least 2.5 cc of gastric secretions within the first hour of birth. For gastric aspirate shake test we added 0.5 cc normal saline and 1cc 95% ethyl alcohol to 0.5 cc of amniotic fluid and shook the test tube well for 15 seconds. Then, we counted the bubbles formed on the surface of the test tube. A cell counter [Sysmex model Xt-1800i] was used to determine the lamellar body counts. We used ROC Curve and kappa coefficient for data analysis. Of 230 samples, 80 were excluded from the study because of contamination with blood or meconium. Finally, 150 samples were analyzed. 59 cases [39/3%] had respiratory distress syndrome. The respective values of sensitivity, specificity, positive and negative predictive values for diagnosis of respiratory distress syndrome were 62.7%, 100%, 80.5% and100% for gastric shake test, and 98.3%, 94.5%, 98.9% and 92.1% for lamellar body count test. Lamellar body count, is a useful test for screening of respiratory distress syndrome and gastric aspirate shake test is also a suitable test to rule out respiratory distress syndrome. By using these 2 tests, we can expect appropriate sensitivity and specificity in the diagnosis of respiratory distress syndrome