Utilization of Lung Ultrasound Score in Decision for Minimally Invasive Surfactant Administration

Respiratory distress syndrome (RDS) is a frequently diagnosed disorder in premature infants admitted to the neonatal intensive care unit (NICU). It is caused by pulmonary immaturity and surfactant deficiency that result in increased alveolar collapse, mismatched ventilation-perfusion and ultimately hypoxia in neonates. Historically, early administration of exogenous surfactant via endotracheal tube has become the mainstay treatment and management of RDS. However, studies have shown neonates receiving invasive mechanical ventilation have higher incidence of developing bronchopulmonary dysplasia (BPD), causing a recent shift to increased use of non-invasive respiratory support for management of RDS. The use of early nasal ventilation and increasing mean airway pressure to improve alveolar stability and functional residual capacity (FRC) helps to improve fraction of inspired oxygen (FiO2) requirements even in the surfactant-deficient infant. This creates a dilemma for neonatologists. It is challenging to determine the severity of RDS in the first hours of life. Current standard is to use a combination of supplemental FiO2 requirement, work of breathing and chest x-ray to assess the need for surfactant replacement therapy (SRT) because there is a subset of infants who will fail non-invasive support and require intubation. Even with improvement in non-invasive RDS management, predicting surfactant deficiency before the deterioration of neonate would allow for earlier SRT and likely improve respiratory outcomes.

Point of care ultrasound (POCUS) is a common modality used in emergency medicine and is a rapidly emerging area of clinical research in neonatal medicine. Lung ultrasound has been shown to provide quick, reliable information via a noninvasive bedside technique in dynamically changing lungs. POCUS in neonatology has been shown to diagnose RDS earlier than waiting for chest x-ray and clinical changes. Studies have shown ultrasound can identify surfactant deficiency before clinical deterioration and decrease need for mechanical ventilation.

With this study, it is proposed to use lung ultrasound with a calculated lung ultrasound score (LUS) to assess severity of RDS and identify surfactant deficiency earlier than current practice of using supplemental FiO2 requirement and clinical status. This will allow earlier SRT, potentially improving short term respiratory outcomes and possibly longer term such as BPD. Similarly, it is proposed to investigate the potential synergy of early SRT using lung ultrasound and non-invasive administration of surfactant in positively impacting respiratory outcomes in moderately preterm and late preterm infants.

Inclusion criteria

• Inborn at 27 0/7 to 34 6/7 weeks of gestational age
• Spontaneously breathing at birth but requiring non-invasive respiratory support
• RDS diagnosed on chest x-ray (diffuse, bilateral, fine granular opacities in lungs, air bronchograms) or were at risk of developing RDS

Exclusion criteria

• Outborn
• Endotracheal intubation in the delivery room or within 2 hours of life
• Surfactant in the delivery room as part of advanced resuscitation
• Presence of major congenital malformations or chromosomal anomalies
• Hydrops fetalis
• Inherited disorders of metabolism
• Air leak syndrome (pneumothorax, pneumomediastinum) prior to surfactant administration, congenital diaphragmatic hernia, congenital pneumonia, meconium aspiration syndrome
• Infants in extremis not expected to survive