Continuous positive pressure ventilation combined with pulmonary surfactant in the treatment of neonatal respiratory distress syndrome

Cortisol regulates neonatal lung development via Smoothened

BACKGROUND

Neonatal respiratory distress syndrome (NRDS), one of the main causes of neonatal death, is clinically characterized by progressive dyspnea and cyanosis 1 to 2 h after birth. Corticosteroids are commonly used to prevent NRDS in clinical. However, the protective mechanism of the corticosteroids remains largely unclear.

METHODS

In this study, the simulation of the molecular docking by Autodock, in vitro binding experiments, and Sonic Hedgehog (SHH) pathway examination in cells were performed to study the directly binding of cortisol to Smoothened (SMO). To explore the effect of cortisol action on the SHH pathway on neonatal lung development, we generated a genetic mouse, in which leucine 116 (L112 in human) of SMO was mutated to alanine 116 (L116A, Smoa/a) by the CRISPR-Cas9, based on sequence differences between human and mice. Then, we performed morphological analysis, single-cell RNA sequencing (scRNA-seq) on lung tissue and fluorescence in situ hybridization (FISH).

RESULTS

In this study, we reported that cortisol, the endogenous glucocorticoid, inhibited the sonic hedgehog (Shh)/SMO-mediated proliferation of lung fibroblasts to maintain the normal lung development. Specifically, cortisol competed with cholesterol for binding to the cysteine-rich domain (CRD) in SMO to inhibit the activation of Shh/SMO signaling, a critical signaling known for cell proliferation. Cortisol did not inhibit the activation of SMO when L112 in its CRD was mutated to A112. Moreover, Smoa/a (L116A) mice exhibited the immature lungs in which over-proliferation of interstitial fibroblasts and reduction in the surfactant protein were evident.

CONCLUSION

Together, these results suggested that cortisol regulated cholesterol stimulation of SMO by competitively binding to the CRD to regulate neonatal lung maturation in mice.

Effect of Nasal Continuous Airway Pressure With and Without Surfactant Administration for the Treatment of Respiratory Distress Syndrome in Preterm Neonates

Background Neonatal respiratory distress syndrome is a common cause of respiratory distress in newborns, often resulting from a lack of surfactant production or premature lung breakdown. The objective of this study was to compare the effect of nasal continuous airway pressure with and without surfactant administration for the treatment of respiratory distress syndrome in preterm neonates. Methodology A comparative analytical study was conducted on 100 neonates (group A continuous positive airway pressure (CPAP) with surfactant = 50 vs. group B CPAP only= 50 ). The group was allocated to the patient according to sequence. In group A, the neonates were given surfactant by the INSURE (intubation, surfactant, extubation) technique via an endotracheal tube with a single dose of 100 mg/kg/dose within the first hours of life followed by CPAP. In group B, the neonates were given only CPAP after birth. At follow-up after 24 hours, pH, pCO2, pO2, positive end-expiratory pressure (PEEP), and FiO2 were documented. All information was recorded on a predesigned questionnaire and results were subjected to statistical analysis to determine the significance of observed differences. Collected data were entered and analyzed using SPSS version 22 (IBM Corp., Armonk, NY, USA). Both groups were compared for mean pH, pCO2, pO2, PEEP, and FiO2 using an independent-sample t-test and effectiveness using a chi-square test. A significant difference was considered when the p-value was ≤0.05. Results Group A had a mean age of 4.84 ± 0.95 hours, while group B had a mean age of 5.5 ± 1.26 hours (p = 0.04). Gender distribution was similar in both groups, with 46.0% males and 54.0% females in group A, and 48.0% males and 52.0% females in group B (p = 0.841). Regarding post-treatment blood gas analysis, group A had a mean pH of 7.30 ± 0.05, and group B had a mean pH of 7.302 ± 0.07. While there was no significant difference in pO2 levels (p = 0.38), there was a substantial difference in pCO2 levels, with group A at 38.26 ± 4.35 and group B at 35.45 ± 4.36 (p = 0.02).CPAP parameters also showed a statistically significant difference in PEEP pCO2, with group A at 4.5 ± 0.73 and group B at 4.16 ± 0.37 (p = 0.004). After treatment, group A exhibited significant improvements in blood gas analysis and CPAP parameters compared to group B. Conclusions The study revealed that both CPAP with and without surfactant treatment effectively treat respiratory distress syndrome in preterm infants, with both being safe, effective, secure, and reducing side effects. However, CPAP treatment without surfactant is a non-invasive and cost-effective option.

Non-invasive respiratory support in preterm infants

Survival of preterm infants has increased steadily over recent decades, primarily due to improved outcomes for those born before 28 weeks of gestation. However, this has not been matched by similar improvements in longer-term morbidity. One of the key long-term sequelae of preterm birth remains bronchopulmonary dysplasia (also called chronic lung disease of prematurity), contributed primarily by the effect of early pulmonary inflammation superimposed on immature lungs. Non-invasive modes of respiratory support have been rapidly introduced providing modest success in reducing the incidence of bronchopulmonary dysplasia when compared with invasive mechanical ventilation, and improved clinical practice has been reported from population-based studies. We present a comprehensive review of the key modes of non-invasive respiratory support currently used in preterm infants, including their mechanisms of action and evidence of benefit from clinical trials.