Detection of carbon dioxide thresholds using low-flow sidestream capnography in ventilated preterm infants.
BACKGROUND
Monitoring CO2 levels in preterm infants receiving mechanical ventilation is designed to avoid the harmful consequences of hypocapnia or hypercapnia. Capnography is of questionable accuracy for monitoring PCO2 in preterm infants.


OBJECTIVE
To determine the accuracy of sidestream capnography in ventilated preterm infants by comparing end-tidal carbon dioxide (EtCO2) values to mixed venous carbon dioxide pressure (PvCO2) and to transcutaneous carbon dioxide pressure (TcPCO2).


METHODS
Simultaneous recordings of EtCO2, TcPCO2 and PvCO2 in 37 ventilated preterm infants. The PvCO2-EtCO2 gradient was calculated. The Bland-Altman technique and the intra-class correlation coefficient (ICC) were used to assess agreement between methods. The area under the curve (AUC) was calculated.


RESULTS
Ninety-nine EtCO2/PvCO2 pairs were studied from 37 preterm infants with a mean gestational age of 27.7 +/- 1.9 weeks and a mean birth weight of 1,003 +/- 331 g. The mean PvCO2-EtCO2 gradient was 11.2 +/- 8.0 mmHg, and the ICC was 0.28. The mean PvCO2-TcPCO2 gradient was 0 +/- 7.8 mmHg, and the ICC was 0.78. AUCs for EtCO2 and TcPCO2 were similar in detecting high or low PvCO2.


CONCLUSIONS
Despite an insufficient correlation between EtCO2 and PvCO2, capnography was able to detect low and high CO2 warning levels with a similar efficacy to that of TcPCO2, and may therefore be of clinical interest.
Lopez
Emmanuel
E
Service de Médecine néonatale, Groupe Hospitalier Cochin-Saint Vincent de Paul, AP-HP, 123 Bd du Port-Royal, 75014 Paris, France. emmanuel.lopez@cch.aphp.fr
Grabar
Sophie
S
Barbier
Alexandre
A
Krauss
Baruch
B
Jarreau
Pierre-Henri
PH
Moriette
Guy
G
D000704:Analysis of Variance; D015982:Bias; D001785:Blood Gas Monitoring, Transcutaneous / Q000379:methods; D019296:Capnography / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D002245:Carbon Dioxide / Q000097:blood*; D016002:Discriminant Analysis; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000097:blood / Q000175:diagnosis; D016857:Hypocapnia / Q000097:blood / Q000175:diagnosis; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D015931:Intensive Care, Neonatal / Q000379:methods*; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods*; D011446:Prospective Studies; D012372:ROC Curve; D012121:Respiration, Artificial / Q000009:adverse effects / Q000379:methods; D012127:Respiratory Distress Syndrome, Newborn / Q000097:blood / Q000628:therapy
D002245:Carbon Dioxide