Evaluation of bubble clicking in gastric aspirate in the newborn

Gastric aspirates were obtained soon after delivery from 167 babies 24 to 40 weeks gestation. Bubble clicking and foam stability tests were compared for their reliability in determining pulmonary maturity. Both tests predicted mature lungs accurately in 90-91% of babies, however their ability to predict immature lungs was less, bubble clicking predicting it accurately in 88% of babies and foam stability test predicting it in 77% of babies. Bubble clicking, foam stability tests, L/S ratio and two dimensional thin layer chromatography were done in 26 gastric aspirates obtained from 22 babies with mature lungs and 4 babies with with hyaline membrane disease. Phosphatidyl glycerol was present in 21 of the 22 babies with mature lungs. Bubble clicking demonstrated a 95% accuracy and foam stability test 100% accuracy in predicting the presence of phosphatidyl glycerol. Bubble clicking is a useful and easily preformed test in the clinical assessment of a preterm baby.