Prediction of surfactant dysfunction in term infants by the click test

Abstract

Pulmonary surfactant dysfunction (inactivation, deficiency) has been implicated in term neonates with respiratory failure. This study has evaluated the click test, a biophysical test for surfactant function, which will be useful in rapidly and reliably identifying term neonates with surfactant dysfunction. Samples of tracheal and or gastric aspirates (0.2 ml) from 55 neonates, varying from 36 to 42 weeks of gestational age, with respiratory distress and fractional inspired oxygen concentration requirements of > 0.5 were shaken with 95% ethanol. Once bubbles formed the samples were examined in air‐free water under a microscope. In a positive click test, the bubbles rhythmically increase and then decrease in size, denoting the presence of active surfactant. When few bubbles were observed, the specimen was labelled as equivocal, and if none were seen, it was called negative. Surfactant dysfunction (negative or equivocal test) was consistently seen in respiratory distress syndrome (RDS), transient tachypnea of the newborn, and severe meconium aspiration syndrome (MAS). Preliminary data suggest that the click test will provide a rapid and early diagnosis of surfactant dysfunction In term neonates. This should facilitate early treatment with exogenous surfactant in RDS, by early a diagnosis of surfactant deficiency, and provide justification for immediate and ongoing surfactant treatment in newborns with MAS. The click test can provide a diagnostic tool for surfactant dysfunction and deficiency in randomized controlled trials of therapy in those disease states in which exogenous surfactant therapy may be useful. Pediatr Pulmonol. 1997; 23:287–291. © 1997 Wiley‐Liss, Inc.

Evaluation of surfactant function at birth determined by the stable microbubble test in term and near term infants with respiratory distress

“…Low levels of phosphatidylcholine and phosphatidylinositol were also reported [12]. Bhuta et al [1] reported reduction of bubble clicking in tracheal and gastric aspirates in patients with TTN, suggesting surfactant dysfunction in this condition.…”

Antenatal Corticosteroids Decrease the Risk of Composite Neonatal Respiratory Morbidity in Planned Early Term Cesarean Deliveries

“…In term infants diagnosed with TTN, surfactant deficiency, and dysfunction have been reported to be the leading determinants of respiratory morbidity. 13 14 Glucocorticoids appear to improve the number and function of sodium channels on the pulmonary epithelium, allowing reabsorption of liquid from the lungs, and this switch from fluid secretion to fluid absorption reduces the risk of TTN. 15 In women undergoing non-labor cesarean delivery, this conversion from fluid secretion to absorption is disrupted without another source of corticosteroids.…”

Interobserver reliability of the click test: A rapid bedside test to determine surfactant function

“…Surfactant dysfunction has been demonstrated using the click test in term infants with meconium aspiration syndrome (MAS), transient tachnypnoea of the newborn, persistent pulmonary hypertension of the newborn, and neonatal ARDS. [21] Infants with MAS were shown to have surfactant dysfunction using the click test until their oxygen requirements decreased to a fraction inspired oxygen of 0.4. Benefits of exogenous surfactant therapy have been shown in a small randomized controlled trial in MAS.…”