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Published on: January 29, 2011
The Precision Between Transcutaneous Carbon Dioxide Versus PaCO in Infants Undergoing Therapeutic Hypothermia
Pranav Garlapati1, Payam Vali1, Satyan Lakshminrusimha1
1Dr Garlapati is affiliated with Newborn Specialists of Tulsa, Tulsa, Oklahoma. Drs Vali and Lakshminrusimha are affiliated with Department of Pediatrics, UC Davis Medical Center, Sacramento, California. Mr Smith is affiliated with Department of Respiratory Care, UC Davis Medical Center, Sacramento, California. Dr Zavorsky is affiliated with Department of Physiology and Membrane Biology, University of California, Davis, Sacramento, California.
Background:
Infants with hypoxic-ischemic encephalopathy are often treated with therapeutic hypothermia and high-frequency ventilation. Fluctuations in PaCO during therapeutic hypothermia are associated with poor neurodevelopmental outcomes. Transcutaneous CO2 monitors offer a noninvasive estimate of PaCO represented by transcutaneously measured partial pressure of carbon dioxide (PtcCO ). We aimed to assess the precision between PtcCO and PaCO values in neonates undergoing therapeutic hypothermia.
Methods:
This was a retrospective chart review of 10 neonates who underwent therapeutic hypothermia requiring respiratory support over 2 y. A range of 2-27 simultaneous PtcCO and PaCO pairs of measurements per neonate were analyzed via linear mixed models and a Bland-Altman plot for multiple observations per neonate.
Results:
A linear mixed-effect model demonstrated that PtcCO and PaCO (controlling for sex) were similar. The 95% CI of the mean difference ranged from -2.3 to 5.7 mm Hg (P = .41). However, precision was poor as the PtcCO ranged from > 18 mm Hg to < 13 mm Hg than PaCO values for 95% of observations.
Conclusions:
The neonates' PtcCO was as much as 18 mm Hg higher to 13 mm Hg lower than the PaCO 95% of the time. Transcutaneous CO2 monitoring may not be a good trending tool, nor is it appropriate for estimating PaCO in patients undergoing therapeutic hypothermia.
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