The stable microbubble test for determining continuous positive airway pressure (CPAP) success in very preterm infants receiving nasal CPAP from birth.

BACKGROUND

Very preterm infants can be treated with nasal continuous positive airway pressure (CPAP) from birth, but some fail. A rapid test, such as the stable microbubble test (SMT) on gastric aspirate, may identify those who can be managed successfully using CPAP.

OBJECTIVE

To determine if SMT can identify soon after birth, very preterm infants who may be successfully managed on CPAP alone.

METHODS

Stable microbubbles (diameter <15 µm) were counted in gastric aspirates taken <1 h of age from infants <30 weeks' gestation, who received CPAP from birth. Infants failed CPAP if intubated at <72 h of age. Clinicians were masked to SMT results. A receiver operating characteristic curve was generated to determine the relationship between number of microbubbles/mm(2) and subsequent intubation.

RESULTS

68 infants of mean (SD) 28.1 (1.4) weeks' gestation received CPAP in the delivery room at a median (interquartile range) pressure 7 (6-8) cmH2O and FiO2 0.25 (0.21-0.3). Gastric aspirates were taken at a median (interquartile range) age of 0.5 (0.3-0.6) hours. The best cut-off point for predicting CPAP success or failure was a SMT count of 8 microbubbles/mm(2). The area under the receiver operating characteristic curve was 0.8 (95% CI 0.7-0.9). A SMT count ≥8 microbubbles/mm(2) had a sensitivity of 53%, a specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 60% for predicting CPAP success.

CONCLUSION

Infants treated with CPAP from birth, who had SMT counts ≥8 microbubbles/mm(2) on their gastric aspirate, did not fail CPAP.