Influence of neonatal endotracheal tube dimensions on oscillometry-acquired reactance: a bench study

Lung function response to postnatal corticosteroids for the prevention and treatment of bronchopulmonary dysplasia

BACKGROUND

Steroid treatment is well-known for producing clinically significant improvements in respiratory support requirements. In this study, we utilized lung ultrasound and respiratory oscillometry to objectively assess this response and determine if the combination of these methods can serve as a valuable tool for comparing different treatment strategies.

METHODS

We conducted a retrospective observational study including preterm infants with a gestational age below 32 weeks and/or a birth weight below 1500 g. We measured lung ultrasound score (LUS) and respiratory system reactance (Xrs) by respiratory oscillometry before and after treatment with either systemic dexamethasone or inhaled budesonide.

RESULTS

We analyzed 46 treatments (9 dexamethasone, 37 budesonide) administered to 40 infants (median (Q1, Q3) postnatal age = 30 (18, 49) days, postmenstrual age = 33.29 (30.14, 35.00) weeks). All treatments were associated with a notable reduction in respiratory support and a concurrent improvement in either Xrs, LUS, or both. On average, Xrs improved from 3.13 (1.09, 5.41) to 0.44 (-0.90, 1.59) z-score (p < 0.001) and LUS from 10 (7, 12) to 5 (3, 8) (p < 0.001).

CONCLUSIONS

Xrs and LUS proved sensitive to lung function changes associated with corticosteroids; combining the two better described the response and its variability.

IMPACT

We found that respiratory system reactance (Xrs) and lung ultrasound score (LUS) are sensitive biomarker for monitoring changes in lung function associated with corticosteroids; Combining Xrs and LUS enhances evaluation compared to each method alone; These results have valuable implications in clinical practice, particularly in personalizing and monitoring corticosteroid treatment; The present paper suggests that the combined use of respiratory oscillometry and lung ultrasound holds value as a research tool in future studies investigating various treatment regimens, molecules, or administration routes.

Combining lung ultrasound and oscillatory mechanics for assessing lung disease in very preterm infants

BACKGROUND

We investigated whether combining lung ultrasound scores (LUSs) and respiratory system reactance (Xrs) measured by respiratory oscillometry explains the severity of lung disease better than individual parameters alone.

METHODS

We performed a prospective observational study in very preterm infants. Forced oscillations (10 Hz) were applied using a neonatal mechanical ventilator (Fabian HFOi, Vyaire). We used the simultaneous respiratory severity score (RSS = mean airway pressure × FIO2) as a primary outcome. We built linear mixed-effect models to assess the relationship between Xrs z-score, LUS and RSS and compared nested models using the likelihood ratio test (LRT).

RESULTS

We enrolled 61 infants (median (Q1, Q3) gestational age = 30.00 (26.86, 31.00) weeks) and performed 243 measurements at a postnatal age of 26 (13, 41) days and postmenstrual age of 33.14 (30.46, 35.86) weeks. Xrs z-score and LUS were independently associated with simultaneous RSS (p < 0.001 for both). The model including Xrs and LUS explained the RSS significantly better than Xrs (p value LRT < 0.001) or LUS alone (p value LRT < 0.001).

CONCLUSIONS

Combining LUS and Xrs z-score explains the severity of lung disease better than each parameter alone and has the potential to improve the understanding of the underlying pathophysiology.

IMPACT

Combining respiratory system reactance by oscillometry and lung ultrasound score explains the respiratory support requirement (e.g., proxy of the severity of lung disease) significantly better than each parameter alone. We assessed the relationship between lung ultrasound and respiratory system reactance in very preterm infants for the first time. Combining respiratory oscillometry and lung ultrasound has the potential to improve the understanding of respiratory pathophysiology.

Oscillometry for personalizing continuous distending pressure maneuvers: an observational study in extremely preterm infants

RATIONALE

Lung recruitment and continuous distending pressure (CDP) titration are critical for assuring the efficacy of high-frequency ventilation (HFOV) in preterm infants. The limitation of oxygenation (peripheral oxygen saturation, SpO2) in optimizing CDP calls for evaluating other non-invasive bedside measurements. Respiratory reactance (Xrs) at 10 Hz measured by oscillometry reflects lung volume recruitment and tissue strain. In particular, lung volume recruitment and decreased tissue strain result in increased Xrs values.

OBJECTIVES

In extremely preterm infants treated with HFOV as first intention, we aimed to measure the relationship between CDP and Xrs during SpO2-driven CDP optimization.

METHODS

In this prospective observational study, extremely preterm infants born before 28 weeks of gestation undergoing SpO2-guided lung recruitment maneuvers were included in the study. SpO2 and Xrs were recorded at each CDP step. The optimal CDP identified by oxygenation (CDPOpt_SpO2) was compared to the CDP providing maximal Xrs on the deflation limb of the recruitment maneuver (CDPXrs).

RESULTS

We studied 40 infants (gestational age at birth = 22+ 6-27+ 5 wk; postnatal age = 1-23 days). Measurements were well tolerated and provided reliable results in 96% of cases. On average, Xrs decreased during the inflation limb and increased during the deflation limb. Xrs changes were heterogeneous among the infants for the amount of decrease with increasing CDP, the decrease at the lowest CDP of the deflation limb, and the hysteresis of the Xrs vs. CDP curve. In all but five infants, the hysteresis of the Xrs vs. CDP curve suggested effective lung recruitment. CDPOpt_SpO2 and CDPXrs were highly correlated (ρ = 0.71, p < 0.001) and not statistically different (median difference [range] = -1 [-3; 9] cmH2O). However, CDPXrs were equal to CDPOpt_SpO2 in only 6 infants, greater than CDPOpt_SpO2 in 10, and lower in 24 infants.

CONCLUSIONS

The Xrs changes described provide complementary information to oxygenation. Further investigation is warranted to refine recruitment maneuvers and CPD settings in preterm infants.