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Regional respiratory time constants during lung recruitment in high-frequency oscillatory ventilated preterm infants

Martijn Miedema1, Frans H de Jongh, Inez Frerichs

  • 1Department of Neonatology, Emma Children's Hospital, Academic Medical Center, P.O. Box 22660, Amsterdam 1100 DD, The Netherlands. m.miedema@amc.uva.nl

Intensive Care Medicine
|November 30, 2011
PubMed

Insights

Surfactant treatment in preterm infants undergoing high-frequency oscillatory ventilation significantly alters lung recruitment time constants, with longer durations observed in dorsal regions post-treatment.

Area of Science:

  • Neonatal Medicine
  • Respiratory Physiology
  • Pediatric Critical Care

Background:

  • Respiratory distress syndrome (RDS) is a common condition in preterm infants.
  • High-frequency oscillatory ventilation (HFOV) is a ventilatory strategy used for RDS.
  • Lung recruitment maneuvers aim to reopen collapsed alveoli.

Purpose of the Study:

  • To evaluate regional respiratory time constants during lung recruitment in preterm infants on HFOV.
  • To compare these constants before and after surfactant administration.
  • To investigate regional differences (ventral vs. dorsal) in lung mechanics.

Main Methods:

  • Stepwise oxygenation-guided lung recruitment was performed in preterm infants on HFOV.
  • Electrical impedance tomography (EIT) monitored lung volume changes.
  • Time constants were calculated using exponential decay fitting for incremental and decremental pressure steps.
  • Analysis included whole chest and regional (ventral/dorsal) data.

Main Results:

  • Before surfactant, incremental pressure steps had longer time constants (27.3s) than decremental steps (16.1s).
  • Post-surfactant, decremental time constants significantly increased (44.3s).
  • Regional analysis post-surfactant showed longer time constants in dorsal (61.2s) compared to ventral (40.3s) lung regions.

Conclusions:

  • Lung volume stabilization during HFOV recruitment in preterm infants is time-dependent (approx. 5 min).
  • Recruitment is influenced by the pressure-volume curve, surfactant status, and lung region.
  • Surfactant administration alters regional lung mechanics, particularly affecting dorsal lung regions.
Abstract

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