Impact of Catheter Choice on Procedural Success of Minimally Invasive Surfactant Therapy

Influence of catheter thickness on respiratory physiology during less invasive surfactant administration in extremely preterm infants

Introduction

Delivering surfactant via thin catheters (minimal-invasive surfactant therapy (MIST); less invasive surfactant administration (LISA)) has become a common procedure. However, the effect of tracheal obstruction caused by catheters of different sizes on tracheal resistance in extremely low gestational age newborns (ELGANs) is unknown.

Methods

To investigate the effect of catheters size 3.5, 5 and 6 French on airway resistance in ELGANs of 23-28 weeks gestational age during LISA, we performed calculations based on Hagen-Poiseuille's law and compared these with a clinically and physically more accurate method: computational fluid dynamics (CFD) simulations of respiratory airflow, performed in 3D virtual airway models derived from MRI.

Results

The presence of the above catheters decreased the cross-sectional area of the infants' tracheal entrance (the cricoid ring) by 13-53%. Hagen-Poiseuille's law predicted an increase in resistance by 1.5-4.5 times and 1.3-2.6 times in ELGANs born at 23 and 28 weeks, respectively. However, CFD simulations demonstrated an even higher increase in resistance of 3.4-85.1 and 1.1-3.5 times, respectively. The higher calculated resistances were due to the extremely narrow remaining lumen at the glottis and cricoid with the catheter inserted, resulting in a stronger glottal jet and turbulent airflow, which was not predicted by Hagen-Poiseuille.

Conclusion

Catheter thickness can greatly increase tracheal resistance during LISA-procedures in ELGANs. Based on these models, it is recommended to use the thinnest catheter possible during LISA in ELGANs to avoid unnecessary increases in airway resistance in infants already experiencing dyspnea due to respiratory distress syndrome.

Purpose Built Catheters for Minimally Invasive Surfactant Therapy: Experience from a Canadian Tertiary Level Neonatal Intensive Care Unit

Background

Minimally invasive surfactant therapy (MIST), a method of surfactant delivery via a thin catheter during spontaneous breathing, is an increasingly popular alternative to intubation and surfactant administration. Recently, purpose-built catheters for MIST received regulatory approval in Canada and became available for use. However, procedural success and user experience with such catheters have not been described.

Methods

This retrospective cohort study included neonates who received MIST using purpose-built catheters between January 1, 2021, and March 31, 2022. Two types of purpose-built catheters were used in this period - SurfCath™ and BLEScath™. Procedural success, number of attempts, and adverse events in neonates receiving MIST via the two catheters were compared using chi-square or Fisher's tests. User experience was described using an ease-of-use scale.

Results

Thirty-seven neonates met eligibility criteria; 22 received MIST via SurfCath™, whereas 15 received MIST via BLEScath™. Success rates were 91% in SurfCath™ and 93% in BLEScath™ (P> 0.994). Failed attempts were lower in SurfCath™ (23%) in comparison to BLEScath™ (33%), but the difference was not statistically significant (P=0.708). Among operators, 90% found SurfCath™ very easy/relatively easy to use compared to 43% of users reflecting the same degree of use with BLEScath™ (P=.021). There was no difference in adverse events.

Conclusion

This is the first study in Canada to report MIST with purpose-built catheters. Overall, the success rate was equally high with both catheters. Users subjectively reported higher ease of use with SurfCath™. Commercially available purpose-built catheters should facilitate universal adaptation of the MIST method.

Prevention of Chronic Morbidities in Extremely Premature Newborns with LISA-nCPAP Respiratory Therapy and Adjuvant Perinatal Strategies

Less invasive surfactant administration techniques, together with nasal continuous airway pressure (LISA-nCPAP) ventilation, an emerging noninvasive ventilation (NIV) technique in neonatology, are gaining more significance, even in extremely premature newborns (ELBW), under 27 weeks of gestational age. In this review, studies on LISA-nCPAP are compiled with an emphasis on short- and long-term morbidities associated with prematurity. Several perinatal preventative and therapeutic investigations are also discussed in order to start integrated therapies as numerous organ-saving techniques in addition to lung-protective ventilations. Two thirds of immature newborns can start their lives on NIV, and one third of them never need mechanical ventilation. With adjuvant intervention, these ratios are expected to be increased, resulting in better outcomes. Optimized cardiopulmonary transition, especially physiologic cord clamping, could have an additively beneficial effect on patient outcomes gained from NIV. Organ development and angiogenesis are strictly linked not only in the immature lung and retina, but also possibly in the kidney, and optimized interventions using angiogenic growth factors could lead to better morbidity-free survival. Corticosteroids, caffeine, insulin, thyroid hormones, antioxidants, N-acetylcysteine, and, moreover, the immunomodulatory components of mother's milk are also discussed as adjuvant treatments, since immature newborns deserve more complex neonatal interventions.

Should less invasive surfactant administration (LISA) become routine practice in US neonatal units?

The harmful effects of mechanical ventilation (MV) on the preterm lung are well established. Avoiding MV at birth and stabilization on continuous positive airway pressure (CPAP) decreases the composite outcome of death or bronchopulmonary dysplasia. Although preterm infants are increasingly being admitted to the neonatal intensive care unit on CPAP, centers differ in the ability to manage infants primarily on CPAP. Over the last decade, less invasive surfactant administration (LISA), a method of administering surfactant with a thin catheter, has been devised and has been shown to decrease the need for MV and improve outcomes compared to surfactant administration via an endotracheal tube following intubation. While LISA has been widely adopted in Europe and other countries, its use is not widespread in the United States. This article provides a summary of the existing evidence on LISA, and practical guidance for US units choosing to implement a change of practice incorporating optimization of CPAP and LISA. IMPACT: The accumulated body of evidence for less invasive surfactant administration (LISA), a widespread practice in other countries, justifies its use as an alternative to intubation and surfactant administration in US neonatal units. This article summarizes the current evidence for LISA, identifies gaps in knowledge, and offers practical tips for the implementation of LISA as part of a comprehensive non-invasive respiratory support strategy. This article will help neonatal units in the US develop guidelines for LISA, provide optimal respiratory support for infants with respiratory distress syndrome, improve short- and long-term outcomes of preterm infants, and potentially decrease costs of NICU care.