Stable Microbubble Test on Tracheal Aspirate for the Diagnosis of Respiratory Distress Syndrome

Abstract

Background: Exogenous surfactant should be used as early as possible in the presence of respiratory distress syndrome (RDS), but diagnosis may only become clear late in the course of the disease. The stable microbubble test (SMT) in the tracheal aspirates could help in the decision to give early surfactant to preterm babies with respiratory distress. Objectives: The objective of this study was to evaluate the accuracy of the SMT on tracheal aspirate for the diagnosis of RDS in newborns requiring mechanical ventilation. Methods: The test was performed on specimens obtained from 74 infants requiring mechanical ventilation, through routine suctioning. Results: Patients with RDS and meconium aspiration syndrome (MAS) had a significantly lower stable microbubble count than non-RDS and non-MAS patients. Preterm infants without RDS had a significantly higher microbubble count than preterm babies with RDS and a similar count to that of term babies. Considering a cutoff point of 120 microbubbles/mm² for the diagnosis of RDS, the sensitivity of the microbubble test was 96.3% (95% CI: 79.1–99.8) and the specificity 97.6% (95% CI: 85.9–99.9). Conclusions: The SMT on tracheal aspirates is accurate for RDS diagnosis and may be useful to support the decision to give surfactant to newborns on mechanical ventilation.

The Stable Microbubble Test for Determining Continuous Positive Airway Pressure (CPAP) Success in Very Preterm Infants Receiving Nasal CPAP from Birth

“…Then, using a rubber cap on the top end of the pipette, it was suctioned and expelled (20 times in quick succession) over an objective micrometre slide (Neubauer Improved Bright Line; Brand GmbH, Wertheim, Germany) with a 10-µm scale. The slide was inverted to form a ‘hanging' drop, allowed to stabilise for 4 min and microbubbles (bubbles <15 µm) [12] were counted under a magnification of 100× (fig. 1).…”

Surfactant deficiency in full‐term newborns with transient tachypnea delivered by elective C‐section

“…The use of the stable microbubble test on gastric aspirate samples has revealed that low microbubble and lamellar body counts may be associated with a longer disease duration and a greater need for oxygen therapy . In recent years, studies involving amniotic liquid, gastric aspirate, and tracheal aspirate samples have shown that the stable microbubble test is a sensitive indicator of pulmonary maturity. However, this method has not been tested on oral fluid samples collected immediately after birth.…”