Oscillatory mechanics at birth for identifying infants requiring surfactant: a prospective, observational trial

Abstract

Background Current criteria for surfactant administration assume that hypoxia is a direct marker of lung-volume de-recruitment. We first introduced an early, non-invasive assessment of lung mechanics by the Forced Oscillation Technique (FOT) and evaluated its role in predicting the need for surfactant therapy. Objectives To evaluate whether lung reactance (Xrs) assessment by FOT within 2 h of birth identifies infants who would need surfactant within 24 h; to eventually determine Xrs performance and a cut-off value for early detection of infants requiring surfactant. Methods We conducted a prospective, observational, non-randomized study in our tertiary NICU in Milan. Eligible infants were born between 27+0 and 34+6 weeks’ gestation, presenting respiratory distress after birth. Exclusion criteria: endotracheal intubation at birth, major malformations participation in other interventional trials, parental consent denied. We assessed Xrs during nasal CPAP at 5 cmH2O at 10 Hz within 2 h of life, recording flow and pressure tracing through a Fabian Ventilator for off-line analysis. Clinicians were blinded to FOT results. Results We enrolled 61 infants, with a median [IQR] gestational age of 31.9 [30.3; 32.9] weeks and birth weight 1490 [1230; 1816] g; 2 infants were excluded from the analysis for set-up malfunctioning. 14/59 infants received surfactant within 24 h. Xrs predicted surfactant need with a cut-off − 33.4 cmH2O*s/L and AUC-ROC = 0.86 (0.76–0.96), with sensitivity 0.85 and specificity 0.83. An Xrs cut-off value of − 23.3 cmH2O*s/L identified infants needing surfactant or respiratory support > 28 days with AUC-ROC = 0.89 (0.81–0.97), sensitivity 0.86 and specificity 0.77. Interestingly, 12 infants with Xrs < − 23.3 cmH2O*s/L (i.e. de-recruited lungs) did not receive surfactant and subsequently required prolonged respiratory support. Conclusion Xrs assessed within 2 h of life predicts surfactant need and respiratory support duration in preterm infants. The possible role of Xrs in improving the individualization of respiratory management in preterm infants deserves further investigation.

Oscillatory mechanics in very preterm infants on continuous positive airway pressure support: Reference values

“…Moreover, our Rrs values were similar, and our Xrs values were higher than those reported by Travers et al in preterm infants off respiratory support 13 . By contrast, our Xrs values were similar to those found by Lavizzari et al in the first hours after birth in a population of infants below 35 weeks gestation using the same device used in the present study at the same distending pressure 7 . Possible differences in FOT outcomes obtained in different populations, with different devices, and using different measurement protocols require further study.…”

“…Zrs is commonly expressed in terms of respiratory system resistance (Rrs) and reactance (Xrs), which in turn represents the elastic and inertive properties of the system. Xrs proved sensitive to neonatal lung disease and was useful in prognosticating respiratory outcomes, 3,4 optimizing respiratory support, 5,6 evaluating the need for and the response to pulmonary medications, 7,8 and objectivizing respiratory outcomes 9 in preterm infants.…”

Biochemical and Lung Function Test Accuracy for Predicting the Need for Surfactant Therapy in Preterm Infants: A Systematic Review

“…We evaluated the accuracy of biochemical and lung function tests to assess the need for surfactant. Eight studies [18][19][20][21][22][23][24][25] addressed the objective of the systematic review. They included four different tests (CT, SMT, LBC on GASP, and FOT) performed in the early postnatal period (within 3 h from birth) to evaluate the need for surfactant in preterm infants ≤34 weeks gestation who did not require intubation at birth.…”

“…The majority of the index tests were biochemical tests on the gastric aspirate (GASP) [18,19,[21][22][23][24][25] in one study only on oral aspirate [23], comprising the click test (CT) [18], the stable microbubble test (SMT) [18,19,[21][22][23][24] and the lamellar body count (LBC) [24,25]. A single study applied lung function testing as an index test: the FOT, evaluating respiratory mechanics, in particular, lung reactance as a marker of lung recruitment [20]. Online supplementary Table 1 describes technical details of the tests' procedure.…”

Understanding the fundamentals of oscillometry from a strip of lung tissue

“…Oscillometry is practical because it is effortless and requires very little cooperation, making it easy to perform for both the subject and the operator. This also means that, in contrast to spirometry, it can be performed in a reliable fashion on infants and children (Gray et al, 2019;Lavizzari et al, 2021;Ducharme et al, 2022), as well as on patients who are very sick (i.e., weak) or afflicted by disabilities (Veldhoen et al, 2022;Vielkind et al, 2022) or other conditions where forced expiratory maneuvers are contraindicated (Jordon et al, 2022). Oscillometry is also useful for many reasons.…”