Abstract: Objective To explore the value of stable micro bubble test (SMT) for early diagnosis of hyaline membrane disease (HMD), and to provide early intervention for clinical diagnosis method of hyaline membrane disease in premature infants. Methods A total of 288 premature infants admitted to neonatal intensive care unit (NICU) of Ankang City Central Hospital from January 1st, 2013 to January 1st, 2016 were involved into the study. The primary gastric juice 1-2 mL was extracted for SMT test within 30 minutes after the birth. The number of the stable micro bubble with diameter < 15 μm was counted by low magnification. The clinical symptoms and X-ray results within 6 h after the birth were used as the gold standard of diagnosis of HMD. The premature infants were divided into the case group and control group. The general information was compared between two groups. The optimal critical stable micro bubble value was determined by the ROC curve. The number of micro bubbles <5/mm2, <10/mm2, <15/mm2 and <20/mm2 were used as the threshold, and the sensitivity, specificity, positive and negative predictive values were calculated for HMD diagnosis. Results Among the 288 cases of premature infants, 91 cases (31.6%) were diagnosed as HMD, 197 cases (68.4%) were diagnosed as non HMD. There were lower gestational age, lower birth weight and more proportion of male babies in the case group compared with those of control group (P＜0.05). There were no significant differences in prenatal usage of hormones, premature rupture of membranes, the proportion of cesarean section and 5-min Apgar scores between two groups. The number of micro bubbles of 15/mm2 was the optimal threshold for diagnosis of HMD, and AUC was 0.80 (0.73-0.84). When the number of micro bubbles of 5/mm2 was used for the diagnosis, 38 cases were in line with the diagnosed as HMD. When the number of micro bubbles of 10-15/mm2 was used for the diagnosis, 16 cases were in line with diagnosed as HMD. The number of micro bubbles of <15/ mm 2 was used as boundary value of HMD. The sensitivity, specificity, positive predictive value, negative predictive value and Youden index for SMT prediction and early diagnosis of HMD were 89.0%, 91.4%, 82.7%, 94.7% and 80.4%, which can be used as predictive indicators of HMD. Conclusion SMT test is simple, rapid, economic, high sensitivity and good specificity, which can effectively predict and early diagnose HMD, and have high clinical value.

Key words: hyaline membrane disease, infant, premature, diseases, lung diseases, early diagnosis, ROC curve, stablemicrobubble test