Usefulness of stable microbubble test of tracheal aspirate for the diagnosis of neonatal respiratory distress syndrome.
OBJECTIVE
To compare the overall accuracy of the stable microbubble test (SM test) with measurement of level of surfactant protein A (SP-A) of tracheal aspirate for the diagnosis of respiratory distress syndrome (RDS).


METHODS
Tracheal aspirates were obtained from neonates on ventilatory support. The SM test was carried out on specimens of tracheal aspirate immediately after collection. Levels of SP-A in tracheal aspirates were determined by enzyme-linked immunosorbent assay (ELISA) method. The results of the SM test and SP-A level of the tracheal aspirates were compared against the clinical diagnosis of RDS based on clinical, radiological and bacteriological findings.


RESULTS
Both the median microbubble counts (6 microbubbles/mm2, range = 0-90) and median SP-A levels (100 micrograms/L, range = 0-67447) of infants with RDS were significantly lower than those of infants with no obvious lung pathology (P < 0.0001), and pneumonia (P < 0.0001). The SM test of tracheal aspirates had higher overall accuracy for the diagnosis of RDS than measurement of SP-A levels (94.6% vs 82.4%). When the receiver operating characteristic (ROC) curves of both tests for RDS were compared, the area under the ROC curve of the SM test was larger (0.9689) than that of the SP-A method (0.8965).


CONCLUSIONS
This study showed that the SM test of tracheal aspirate was a useful bedside diagnostic test for RDS. It could be carried out at any time after birth on infants requiring ventilatory support.
Boo
N Y
NY
Department of Paediatrics, Faculty of Medicine, National University of Malaysia, Kuala Lumpur, Malaysia.
Cheong
K B
KB
Cheong
S K
SK
Lye
M S
MS
Zulfiqar
M A
MA
D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D005122:Exudates and Transudates / Q000737:chemistry*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D015588:Observer Variation; D011510:Proteolipids / Q000032:analysis*; D015272:Pulmonary Medicine / Q000379:methods; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000032:analysis*; D015203:Reproducibility of Results; D012121:Respiration, Artificial; D012127:Respiratory Distress Syndrome, Newborn / Q000175:diagnosis* / Q000628:therapy; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014132:Trachea / Q000378:metabolism*
D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants