Regional and overall ventilation inhomogeneities in preterm and term-born infants

Abstract

Objectives: We compared ventilation inhomogeneity assessed by electrical impedance tomography (EIT) and multiple breath washout (MBW) in preterm and term-born infants. We hypothesised that EIT measurements in spontaneously breathing infants are repeatable and that differences in regional ventilation distribution measured by EIT can distinguish between preterm and term-born infants. Design: Cross-sectional group comparison study. Setting: Lung function laboratory at a University Children's Hospital. Participants: Seventeen healthy term-born and 15 preterm infants at a matched postmenstrual age of 44 weeks. Measurements and results: We concurrently measured ventilation inhomogeneity by EIT, ventilation inhomogeneity (LCI) and functional residual capacity (FRC) by MBW and tidal breathing variables during unsedated quiet sleep. EIT measurements were highly repeatable (coefficient of variation 3.6%). Preterm infants showed significantly more ventilation of the independent parts of the lungs compared to healthy term-born infants assessed by EIT (mean difference 5.0, 95 CI 1.3-8%). Whereas the two groups showed no differences in lung volumes or ventilation inhomogeneities assessed by MBW, EIT discriminated better between term and preterm infants. (FRC/kg: mean difference 1.1 mL, 95% CI -1.4-3.8 mL; LCI: mean difference 0.03, 95% CI -0.32-0.25). Conclusions: EIT shows distinct differences in ventilation distribution between preterm and term-born infants, which cannot be detected by MBW. Although preterm infants are capable of dynamically maintaining overall functional residual volume and ventilation distribution, they show some spatial differences from fullterm infants.

Normative data for lung function and exhaled nitric oxide in unsedated healthy infants

“…Subsets of the lung function data have been previously published [12][13][14][15][16][17][18][19][20][21]. The aim of this article is to summarise cohort data and to present a comprehensive set of reference values for all measured lung function parameters as normative and reference values in a white, Middle European population of the given age.…”

Distribution of tidal ventilation during volume-targeted ventilation is variable and influenced by age in the preterm lung

“…The first three, 30-s, artefact-free periods were selected, each from separate recordings. To determine DZ due to ventilation (DZ VT ), a low-pass filter was applied to the impedance signal at 10 breaths/min above the respiratory rate to eliminate signal noise and cardiac-associated impedance changes [15,16,22,23].…”

“…EIT is simple to use, non-invasive and independent of flow and has been validated against computed tomography, scintigraphy and gas wash-out techniques as a method for determining the relative distribution of ventilation [18][19][20][21][22]. EIT exploits differences in electrical impedance generated by changes in lung tissue conductivity due to tidal variations of gas volume during respiration [15,18,21,23,24] and has previously been used to describe regional ventilation characteristics in spontaneously breathing [16,25] and mechanically ventilated infants [22]. Understanding the distribution of ventilation in the preterm lung may improve SIPPV ?…”

Electrical Impedance Tomography in Acute Respiratory Distress Syndrome

“…The phase lag in regional lung filling and emptying can be detected [61] and delayed ventilation onset revealed [47]. The regional response of the lung tissue to a stepwise change in airway pressure can be studied by EIT and regional respiratory time constants determined [42].…”