By Piriya Mahendra, medwireNews Reporter
End tidal carbon dioxide (EtCO2) and transcutaneous carbon dioxide (TcCO2) could be useful to monitor partial pressure of arterial CO2 (PaCO2) in neonates after surgery, a study shows.
"This study suggests that both TcCO2 and sidestream EtCO2 are reliable methods to describe PaCO2 trends in the postoperative period," remark David Tingay (Royal Children's Hospital, Melbourne, Australia) and colleagues.
The study of 50 mechanically ventilated neonates without lung disease revealed that the respective mean PaCO2, EtCO2, and TcCO2 values were 43.6 mmHg, 39.4 mmHg, and 44.3 mmHg, respectively, with EtCO2 being significantly lower than PaCO2 and TcCO2.
Overall, EtCO2 underestimated PaCO2, with a PaCO2-EtCO2 bias of 4.1 mmHg. TcCO2 approximated PaCO2, but with wider limits of agreement bias that were independent of PaCO2.
Overall, 56.1% of EtCO2 values and 60.6% of TcCO2 values were within 5 mmHg of PaCO2. Only 27.3% and 35.6% of EtCO2 and TcCO2 values were within 2 mmHg of PaCO2.
Subgroup analysis revealed that tidal volumes of 10 mL or more, or 4.5 mL/kg or more, resulted in better agreement between both EtCO2 and TcCO2 with PaCO2.
The authors explain that the benefit of continuous CO2 monitoring in ventilated neonates was previously well established, but not universally applied.
Indeed, although TcCO2 is widely used to monitor PaCO2 in the neonatal intensive care unit (NICU), it is rarely used during or after surgical procedures. EtCO2 is also rarely used in the NICU due to variable accuracy in preterm neonates and neonates with severe respiratory failure.
"To our knowledge, this is the largest comparative study of noninvasive CO2 monitoring in ventilated neonates, and the first to selectively identify a population in which neither EtCO2 nor TcCO2 has significant technical disadvantages," Tingay et al conclude in the Archives of Diseases in Childhood: Fetal and Neonatal Edition.
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