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Oscillometry for personalizing continuous distending pressure maneuvers: an observational study in extremely preterm
Chiara Veneroni1, Raffaele L Dellacà2, Erik Küng3
1TechRes Lab, Department of Electronics, Information and Biomedical Engineering (DEIB), Politecnico di Milano University, Via G. Colombo 40, Milan, 20133, Italy.
Insights
Respiratory reactance (Xrs) offers valuable insights beyond oxygen saturation for optimizing high-frequency oscillatory ventilation (HFOV) settings in preterm infants. This non-invasive measure aids in lung recruitment and continuous distending pressure (CDP) titration.
Area of Science:
- Neonatal Medicine
- Respiratory Physiology
- Pediatric Critical Care
Background:
- High-frequency oscillatory ventilation (HFOV) requires precise lung recruitment and continuous distending pressure (CDP) titration for efficacy in preterm infants.
- Peripheral oxygen saturation (SpO2) is limited in optimizing CDP, necessitating alternative non-invasive bedside measurements.
- Respiratory reactance (Xrs) at 10 Hz, measured by oscillometry, reflects lung volume recruitment and tissue strain, with increased Xrs indicating improved recruitment.
Purpose of the Study:
- To investigate the relationship between CDP and Xrs during SpO2-driven CDP optimization in extremely preterm infants receiving HFOV as a primary treatment.
- To compare the optimal CDP determined by oxygenation (CDP_Opt_SpO2) with the CDP that yields maximal Xrs during the deflation limb of lung recruitment maneuvers (CDP_Xrs).
Main Methods:
- A prospective observational study involving extremely preterm infants (born before 28 weeks gestation) undergoing SpO2-guided lung recruitment.
- Simultaneous recording of SpO2 and Xrs at various CDP steps during HFOV.
- Comparison of CDP_Opt_SpO2 with CDP_Xrs to assess the correlation and agreement between the two methods.
Main Results:
- Measurements were well-tolerated and reliable in 96% of 40 infants studied.
- Xrs generally decreased during inflation and increased during deflation, with heterogeneous responses among infants.
- CDP_Opt_SpO2 and CDP_Xrs showed a high correlation (ρ = 0.71, p < 0.001) but differed significantly in 30 out of 40 infants, indicating potential discrepancies in optimal settings.
Conclusions:
- Changes in Xrs provide complementary information to SpO2 for assessing lung recruitment during HFOV in preterm infants.
- Further research is needed to refine lung recruitment strategies and CDP settings using Xrs measurements.
- Xrs measurements may offer a more nuanced approach to lung volume optimization than SpO2 alone.
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.
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