Influence of gestational age on dead space and alveolar ventilation in preterm infants ventilated with volume guarantee

R.P. Neumann, Jane Pillow, C. Thamrin, Alexander Larcombe, Graham Hall, Sven Schulzke

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Background: Ventilated preterm infant lungs are vulnerable to overdistension and underinflation. The optimal ventilator- delivered tidal volume ( VT ) in these infants is unknown and may depend on the extent of alveolarisation at birth.

Objectives: We aimed to calculate respiratory dead space (V D ) from the molar mass (MM) signal of an ultrasonic flowmeter (VD,MM ) in very preterm infants on volume-targeted ventilation (VT target, 4-5 ml/kg) and to study the association between gestational age (GA) and VD,MM -to- VT ratio (VD,MM /VT ), alveolar tidal volume (V A ) and alveolar minute volume (AMV).

Methods: This was a single-centre, prospective, observational, cohort study in a neonatal intensive care unit. Tidal breathing analysis was performed in ventilated very preterm infants (GA range 23-32 weeks) on day 1 of life. Results: Valid measurements were obtained in 43/51 (87%) infants. Tidal breathing variables were analysed using multivariable linear regression. VD,MM / VT was negatively associated with GA after adjusting for birth weight Z score (p <0.001, R2 = 0.26). This association was primarily influenced by the appliance dead space. Despite similar VT /kg and V A /kg across all studied infants, respiratory rate and AMV/kg increased with GA.

 Conclusions: V D,app rather than anatomical V D is the major factor influencing increased VD,MM / VT at a younger GA. A volume guarantee setting of 4-5 ml/kg in the Dräger Babylog ® 8000 plus ventilator may be inappropriate as a universal target across the GA range of 23-32 weeks. Differences between measured and set VT and the dependence of this difference on GA require further investigation.© 2014 S. Karger AG, Basel.

Original languageEnglish
Pages (from-to)43-49
JournalNeonatalogy
Volume107
Issue number1
DOIs
Publication statusPublished - Jan 2015

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