Background:Early treatment with exogenous surfactant is associated with better outcome in neonates with Hyaline membrane disease (HMD), but diagnosis may only become clear late in the course of the disease. In order to rapidly and reliably identify such neonates, we have evaluated the Gastric aspirate shake test (GAST).
Methods:Eighty one neonates with gestational age less than 34 weeks enrolled to this study (51 newborns without pulmonary diseases and 31 newborns with HMD). The clinical characteristics of HMD considered as the gold standard of diagnosis. About 1 ml mixture of normal saline (0.5ml) and stomach contents were collected within 30 minutes of birth (0.5ml) were shaking for 15 seconds into a glass test tube. Then 1 ml of 95% ethanol was injected into the test tube and the 2 ml mixture of gastric aspirate, saline and alcohol agitated for a further 15 seconds. After a waiting time of 15 min, the surface of fluid was examined for bubbles to decide the result of shake test. If no bubbles were present then the test was NEGATIVE (very little surfactant). If bubbles were seen around the top of the fluid but not enough bubbles were present to completely cover the surface, then the test was INTERMEDIATE (only some surfactant). If bubbles were present right across the surface of the fluid, then the test was POSITIVE (adequate amounts of surfactant).
Findings: All infants who developed HMD had negative or intermediate test results. The GAST had a specificity of 66%, sensitivity of 100%, positive predictive value of 64.5% and negative predictive value of 100% for developing HMD. The sensitivity and specificity of the GAST for prediction of surfactant requirement in HMD patients were 100% and 64.8%, respectively, with a positive and negative predictive value of 62.5% and 100%, respectively.
Conclusion: We conclude that the GAST on gastric aspirates obtained within 0.5 hour of delivery is a rapid and simple procedure for rule out of HMD and surfactant requirement.

Key words:Gastric aspirate shake test, Hyaline membrane disease, Surfactant, Neonate.