Easy breathing : exploring aspects of interfaces and devices for neonatal respiratory support

Background: Newborn infants often need respiratory support at birth, particularly those born prematurely. Non-invasive approach is the commended method when supporting spontaneously breathing infants with respiratory distress. This is associated with improved outcome compared to mechanical ventilation. Continuous positive airway pressure (CPAP) is predominantly delivered with nasal interfaces while T-piece with face mask has been the common mode for neonatal stabilisation. The evidence is inconclusive on which interface is best suited to optimise clinical effect and outcome. Nasal interfaces for resuscitation have gained increased attention in recent years.

Objectives: First, to quantify and compare leakage for nasal mask and nasal prongs, during CPAP treatment and to evaluate if simple care adjustments can reduce leakage. Second, to examine if infants exhale through the CPAP device by analysing flow curves from the first trial. Third, evaluate the feasibility of the simplified rPAP system for delivery room stabilisation and continued support. Fourth, to evaluate the effect of dead space on the time delay in oxygen delivery during positive pressure ventilation in simulated settings.

Methods: A randomised cross-over study on 50 infants treated with nasal CPAP (nCPAP) was conducted. Leakage measurements were done with two different nasal interfaces. Then, respiratory flow-curves from the first study were retrospectively analysed (study II). In the third study we conducted a clinical feasibility trial of 32 preterm infants needing respiratory support directly after birth. Lastly, the time course for changes in FiO2 to reach the airway level, was measured and compared between different T-pieces and interfaces in a bench study (study IV).

Results: We found higher leakage for nasal mask vs prongs. Leakage was common for both interfaces and could be reduced with simple maneuvers. In 43/100 recordings, infants treated with nCPAP, exhaled through the CPAP system. We found it feasible to use the new rPAP system for both stabilisation and extended respiratory support in the first hours. Mean time to reach desired FiO2 level was significantly shorter for rPAP with prongs compared to T-pieces with face mask.

Conclusions: Leakage during nasal CPAP treatment is common and can be minimised. Infants can exhale through the CPAP device with nasal mask and prongs. Using the same system for stabilisation and continued support is achievable and can promote stabilisation near parents. There is considerable delay in achieving changes in oxygen concentration during simulated positive pressure ventilation attributable to the dead space of the interface.

List of scientific papers

This thesis is based on the following papers which are referred to in the text by their roman numerals.

I. Falk M, Gunnarsdottir K, Baldursdottir S, Donaldsson S, Jonsson B, Drevhammar T. Interface leakage during neonatal CPAP treatment: a randomised, cross-over trial. Archives of Disease in Childhood - Fetal and Neonatal Edition. 2021;106(6):663-7. https://doi.org/10.1136/archdischild-2021-321579

II. Gunnarsdottir K, Falk M, Baldursdottir S, Donaldsson S, Jonsson B, Drevhammar T. Do newborn infants exhale through the CPAP system? Secondary analysis of a randomised cross-over trial. Archives of Disease in Childhood - Fetal and Neonatal Edition 2023;108:232-236. https://doi.org/10.1136/archdischild-2022-324462

III. *Baldursdottir S, *Gunnarsdottir K, Donaldsson S, Jonsson B, Drevhammar T. Skin-to-skin stabilisation and uninterrupted respiratory support for preterm infants after birth: feasibility of a new and simplified rPAP system. Arch Dis Child Fetal Neonatal Ed 2024;0:F1-F5. *Shared first author. https://doi.org/10.1136/archdischild-2023-326409

IV. Gunnarsdottir K, Stenson B, Foglia E.E, Kapadia V, Drevhammar T, Donaldsson S. Effect of interface dead-space on the time taken to achieve changes in set FiO2 during T-piece ventilation. Is face mask the optimal interface for neonatal stabilisation? Arch Dis Child Fetal Neonatal Ed 2024;0:F1-F6. https://doi.org/10.1136/archdischild-2024-327236