Pathophysiology of gas exchange impairment in extreme prematurity: Insights from combining volumetric capnography and measurements of ventilation/perfusion ratio

Theodore Dassios; Emma E. Williams; J. Gareth Jones; Anne Greenough

doi:10.3389/fped.2023.1094855

Pathophysiology of gas exchange impairment in extreme prematurity: Insights from combining volumetric capnography and measurements of ventilation/perfusion ratio

Theodore Dassios^*, Emma E. Williams, J. Gareth Jones, Anne Greenough

^*Corresponding author for this work

Women & Children's Health

Research output: Contribution to journal › Article › peer-review

1 Citation (Scopus)

Abstract

Background: Infants born extremely preterm often suffer from respiratory disease and are invasively ventilated. We aimed to test the hypothesis that gas exchange in ventilated extremely preterm infants occurs both at the level of the alveoli and via mixing of fresh deadspace gas in the airways. Methods: We measured the normalised slopes of phase II and phase III of volumetric capnography and related them with non-invasive measurements of ventilation to perfusion ratio (V_A/Q) and right-to-left shunt in ventilated extremely preterm infants studied at one week of life. Cardiac right-to-left shunt was excluded by concurrent echocardiography. Results: We studied 25 infants (15 male) with a median (range) gestational age of 26.0 (22.9–27.9) weeks and birth weight of 795 (515–1,165) grams. The median (IQR) V_A/Q was 0.52 (0.46–0.56) and shunt was 8 (2–13) %. The median (IQR) normalised slope of phase II was 99.6 (82.7–116.1) mmHg and of phase III was 24.6 (16.9–35.0) mmHg. The V_A/Q was significantly related to the normalised slope of phase III (ρ = −0.573, p = 0.016) but not to the slope of phase II (ρ = 0.045, p = 0.770). The right-to-left shunt was not independently associated with either the slope of phase II or the slope of phase III after adjusting for confounding parameters. Conclusions: Abnormal gas exchange in ventilated extremely preterm infants was associated with lung disease at the alveolar level. Abnormal gas exchange at the level of the airways was not associated with quantified indices of gas exchange impairment.

Original language	English
Article number	1094855
Journal	Frontiers in Pediatrics
Volume	11
DOIs	https://doi.org/10.3389/fped.2023.1094855
Publication status	Published - 2023

Keywords

extreme prematurity
gas exchange
right to left shunt
ventilation to perfusion ratio
volumetric capnography

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10.3389/fped.2023.1094855

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@article{ddacf1d1b52c45c8a222a587b946be13,

title = "Pathophysiology of gas exchange impairment in extreme prematurity: Insights from combining volumetric capnography and measurements of ventilation/perfusion ratio",

abstract = "Background: Infants born extremely preterm often suffer from respiratory disease and are invasively ventilated. We aimed to test the hypothesis that gas exchange in ventilated extremely preterm infants occurs both at the level of the alveoli and via mixing of fresh deadspace gas in the airways. Methods: We measured the normalised slopes of phase II and phase III of volumetric capnography and related them with non-invasive measurements of ventilation to perfusion ratio (VA/Q) and right-to-left shunt in ventilated extremely preterm infants studied at one week of life. Cardiac right-to-left shunt was excluded by concurrent echocardiography. Results: We studied 25 infants (15 male) with a median (range) gestational age of 26.0 (22.9–27.9) weeks and birth weight of 795 (515–1,165) grams. The median (IQR) VA/Q was 0.52 (0.46–0.56) and shunt was 8 (2–13) %. The median (IQR) normalised slope of phase II was 99.6 (82.7–116.1) mmHg and of phase III was 24.6 (16.9–35.0) mmHg. The VA/Q was significantly related to the normalised slope of phase III (ρ = −0.573, p = 0.016) but not to the slope of phase II (ρ = 0.045, p = 0.770). The right-to-left shunt was not independently associated with either the slope of phase II or the slope of phase III after adjusting for confounding parameters. Conclusions: Abnormal gas exchange in ventilated extremely preterm infants was associated with lung disease at the alveolar level. Abnormal gas exchange at the level of the airways was not associated with quantified indices of gas exchange impairment.",

keywords = "extreme prematurity, gas exchange, right to left shunt, ventilation to perfusion ratio, volumetric capnography",

author = "Theodore Dassios and Williams, {Emma E.} and Jones, {J. Gareth} and Anne Greenough",

note = "Funding Information: This project was funded by King{\textquoteright}s College London 2018 Medical Research Council Confidence in Concept Award through the King's Health Partners' Research and Development Challenge Fund. Publisher Copyright: 2023 Dassios, Williams, Jones and Greenough.",

year = "2023",

doi = "10.3389/fped.2023.1094855",

language = "English",

volume = "11",

journal = "Frontiers in Pediatrics",

issn = "2296-2360",

publisher = "Frontiers Media S.A.",

}

TY - JOUR

T1 - Pathophysiology of gas exchange impairment in extreme prematurity

T2 - Insights from combining volumetric capnography and measurements of ventilation/perfusion ratio

AU - Dassios, Theodore

AU - Williams, Emma E.

AU - Jones, J. Gareth

AU - Greenough, Anne

N1 - Funding Information: This project was funded by King’s College London 2018 Medical Research Council Confidence in Concept Award through the King's Health Partners' Research and Development Challenge Fund. Publisher Copyright: 2023 Dassios, Williams, Jones and Greenough.

PY - 2023

Y1 - 2023

N2 - Background: Infants born extremely preterm often suffer from respiratory disease and are invasively ventilated. We aimed to test the hypothesis that gas exchange in ventilated extremely preterm infants occurs both at the level of the alveoli and via mixing of fresh deadspace gas in the airways. Methods: We measured the normalised slopes of phase II and phase III of volumetric capnography and related them with non-invasive measurements of ventilation to perfusion ratio (VA/Q) and right-to-left shunt in ventilated extremely preterm infants studied at one week of life. Cardiac right-to-left shunt was excluded by concurrent echocardiography. Results: We studied 25 infants (15 male) with a median (range) gestational age of 26.0 (22.9–27.9) weeks and birth weight of 795 (515–1,165) grams. The median (IQR) VA/Q was 0.52 (0.46–0.56) and shunt was 8 (2–13) %. The median (IQR) normalised slope of phase II was 99.6 (82.7–116.1) mmHg and of phase III was 24.6 (16.9–35.0) mmHg. The VA/Q was significantly related to the normalised slope of phase III (ρ = −0.573, p = 0.016) but not to the slope of phase II (ρ = 0.045, p = 0.770). The right-to-left shunt was not independently associated with either the slope of phase II or the slope of phase III after adjusting for confounding parameters. Conclusions: Abnormal gas exchange in ventilated extremely preterm infants was associated with lung disease at the alveolar level. Abnormal gas exchange at the level of the airways was not associated with quantified indices of gas exchange impairment.

AB - Background: Infants born extremely preterm often suffer from respiratory disease and are invasively ventilated. We aimed to test the hypothesis that gas exchange in ventilated extremely preterm infants occurs both at the level of the alveoli and via mixing of fresh deadspace gas in the airways. Methods: We measured the normalised slopes of phase II and phase III of volumetric capnography and related them with non-invasive measurements of ventilation to perfusion ratio (VA/Q) and right-to-left shunt in ventilated extremely preterm infants studied at one week of life. Cardiac right-to-left shunt was excluded by concurrent echocardiography. Results: We studied 25 infants (15 male) with a median (range) gestational age of 26.0 (22.9–27.9) weeks and birth weight of 795 (515–1,165) grams. The median (IQR) VA/Q was 0.52 (0.46–0.56) and shunt was 8 (2–13) %. The median (IQR) normalised slope of phase II was 99.6 (82.7–116.1) mmHg and of phase III was 24.6 (16.9–35.0) mmHg. The VA/Q was significantly related to the normalised slope of phase III (ρ = −0.573, p = 0.016) but not to the slope of phase II (ρ = 0.045, p = 0.770). The right-to-left shunt was not independently associated with either the slope of phase II or the slope of phase III after adjusting for confounding parameters. Conclusions: Abnormal gas exchange in ventilated extremely preterm infants was associated with lung disease at the alveolar level. Abnormal gas exchange at the level of the airways was not associated with quantified indices of gas exchange impairment.

KW - extreme prematurity

KW - gas exchange

KW - right to left shunt

KW - ventilation to perfusion ratio

KW - volumetric capnography

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U2 - 10.3389/fped.2023.1094855

DO - 10.3389/fped.2023.1094855

M3 - Article

AN - SCOPUS:85151267679

SN - 2296-2360

VL - 11

JO - Frontiers in Pediatrics

JF - Frontiers in Pediatrics

M1 - 1094855

ER -

Pathophysiology of gas exchange impairment in extreme prematurity: Insights from combining volumetric capnography and measurements of ventilation/perfusion ratio

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