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Physiological and anatomical dead space in mechanically ventilated newborn infants

Research output: Contribution to journalArticlepeer-review

Theodore Dassios, Paul Dixon, Ann Hickey, Sotirios Fouzas

Original languageEnglish
JournalPediatric Pulmonology
Early online date20 Nov 2017
Accepted/In press1 Nov 2017
E-pub ahead of print20 Nov 2017


King's Authors


Objectives: To compare the anatomical (VD-Ana) and alveolar dead space (VD-Alv) in term and prematurely born infants and identify the clinical determinants of those indices. Working Hypothesis: VD-Ana and VD-Alv will be higher in prematurely born compared to term born infants. Study Design: Retrospective analysis of data collected at King's College Hospital NHS Foundation Trust, London, UK. Patient Selection: Fifty-six infants (11 term, 45 preterm) were studied at a median age of 8 (IQR 2-33) days. Methodology: VD-Ana was determined using Fowler's method of volumetric capnography. VD-Alv was determined by subtracting VD-Ana from the physiological dead space which was determined by the Bohr-Enghoff equation. VD-Ana and VD-Alv were related to body weight at the time of study. Results: The median VD-Ana/kg was higher in prematurely born infants [3.7 (IQR: 3.0-4.5)mL/kg] compared to term infants [2.4 (IQR: 1.9-2.9)mL/kg, adjusted P=0.001]. The median VD-Alv/kg was not higher in prematurely born infants [0.3 (IQR: 0.1-0.5)] compared to term infants [0.1 (IQR: 0.0-0.2)mL/kg] after adjusting for differences in respiratory rate and days of ventilation (P=0.482).VD-Ana/kg was related to postmenstrual age (r=-0.388, P<0.001), birth weight (r=-0.397, P<0.001), and weight at measurement (r=-0.476, P<0.001). VD-Alv/kg was related to postmenstrual age (r=-0.254, P<0.001), birth weight (r=-0.291, P=0.002), and weight at measurement (r=-0.281, P=0.003) and related to days of ventilation (r=0.194, P=0.044). Conclusions: VD-Ana/kg and VD-Alv/kg increased with decreasing weight and gestation. VD-Alv was higher in infants that have undergone prolonged mechanical ventilation.

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