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Non-invasive accurate measurement of arterial PCO2 in a pediatric animal model


Fierstra, Jorn; Winter, Jeff D; Machina, Matthew; Lukovic, Jelena; Duffin, James; Kassner, Andrea; Fisher, Joseph A (2013). Non-invasive accurate measurement of arterial PCO2 in a pediatric animal model. Journal of Clinical Monitoring and Computing, 27(2):147-155.

Abstract

The PCO2 in arterial blood (PaCO2) is a good parameter for monitoring ventilation and acid-base changes in ventilated patients, but its measurement is invasive and difficult to obtain in small children. Attempts have been made to use the partial pressure of CO2 in end-tidal gas (PETCO2), as a noninvasive surrogate for PaCO2. Studies have revealed that, unfortunately, the differences between PETCO2 and PaCO2 are too variable to be clinically useful. We hypothesized that end-inspiratory rebreathing, previously shown to equalize PETCO2 and PaCO2 in spontaneously breathing humans, would also be effective with positive pressure ventilation. Eight newborn Yorkshire pigs were mechanically ventilated via a partial rebreathing circuit to implement end-inspiratory rebreathing. Arterial blood was sampled and tested for PaCO2. A variety of alveolar ventilations resulting in different combinations of end-tidal PCO2 (30-50 mmHg) and PO2 (35-500 mmHg) were tested for differences between PETCO2 and PaCO2 (PET-aCO2). The PET-aCO2 of all samples was (mean ± 1.96 SD) 0.4 ± 2.7 mmHg. Our study demonstrates that, in ventilated juvenile animals, end-inspiratory rebreathing maintains PET-aCO2 to what would be a clinically useful range. If verified clinically, this approach could open the way for non-invasive monitoring of arterial PCO2 in critically ill patients.

Abstract

The PCO2 in arterial blood (PaCO2) is a good parameter for monitoring ventilation and acid-base changes in ventilated patients, but its measurement is invasive and difficult to obtain in small children. Attempts have been made to use the partial pressure of CO2 in end-tidal gas (PETCO2), as a noninvasive surrogate for PaCO2. Studies have revealed that, unfortunately, the differences between PETCO2 and PaCO2 are too variable to be clinically useful. We hypothesized that end-inspiratory rebreathing, previously shown to equalize PETCO2 and PaCO2 in spontaneously breathing humans, would also be effective with positive pressure ventilation. Eight newborn Yorkshire pigs were mechanically ventilated via a partial rebreathing circuit to implement end-inspiratory rebreathing. Arterial blood was sampled and tested for PaCO2. A variety of alveolar ventilations resulting in different combinations of end-tidal PCO2 (30-50 mmHg) and PO2 (35-500 mmHg) were tested for differences between PETCO2 and PaCO2 (PET-aCO2). The PET-aCO2 of all samples was (mean ± 1.96 SD) 0.4 ± 2.7 mmHg. Our study demonstrates that, in ventilated juvenile animals, end-inspiratory rebreathing maintains PET-aCO2 to what would be a clinically useful range. If verified clinically, this approach could open the way for non-invasive monitoring of arterial PCO2 in critically ill patients.

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7 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Clinic for Neurosurgery
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:2013
Deposited On:13 Mar 2014 14:20
Last Modified:28 Mar 2017 10:28
Publisher:Springer
ISSN:1387-1307
Publisher DOI:https://doi.org/10.1007/s10877-012-9403-8
PubMed ID:23100168

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