A dynamic model for assessing the impact of diffusing capacity on arterial oxygenation during apnea

Scott Sands, Vanessa Jane Kelly, Bradley Allan Edwards, Malcolm Davidson, Malcolm Howard Wilkinson, Philip John Berger

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5 Citations (Scopus)

Abstract

Preterm infants have a reduced pulmonary diffusing capacity that has been invoked to explain rapid arterial O(2)-desaturation during apnea, despite little evidence to support this view. We explored the role of diffusion limitation on O(2)-desaturation during apnea by developing a mathematical model of gas exchange in which O(2) dynamically loads the blood traversing the pulmonary capillary. While normal diffusing capacity DL((O(2)) had negligible impact on apneic desaturation, reduced DL((O(2)) advanced the onset of desaturation during apnea. Unexpectedly, despite considerable diffusion limitation, its influence on O(2)-desaturation disappeared within 15s, because its impact in slowing alveolar O(2) depletion maintained a higher driving pressure for diffusion. In contrast, reduced DL((O(2)) substantially slowed reoxygenation following apnea. Our findings do not support the hypothesis that reduced DL((O(2)) explains the rapid apneic desaturation observed in preterm infants. Instead, the signature of reduced DL((O(2)) is a prolonged hypoxemia following apnea, potentially causing a persistence of hypoxic conditions when heart rate and cardiac workload reach a peak.
Original languageEnglish
Pages (from-to)193 - 200
Number of pages8
JournalRespiratory Physiology & Neurobiology
Volume171
Issue number3
DOIs
Publication statusPublished - 2010

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