Cardiac output measurement using a modified carbon dioxide Fick method: a validation study in ventilated lambs

Area of Science:

• Neonatal physiology
• Cardiovascular research
• Medical device validation

Background:

• Accurate cardiac output measurement is crucial for neonatal care.
• Existing methods may be invasive or less practical in ventilated newborns.
• The modified carbon dioxide Fick (mCO2F) method offers a potential alternative.

Purpose of the Study:

• To validate the mCO2F method for measuring cardiac output in newborn lambs.
• To compare mCO2F-derived cardiac output (Q(mCO2F)) with invasive pulmonary blood flow measurements.
• To assess the impact of venous blood sampling site on accuracy.

Main Methods:

• A validation study was conducted on seven ventilated newborn lambs.
• Cardiac output was manipulated via induced hemorrhagic hypotension.
• Q(mCO2F) was measured and compared to pulmonary blood flow (Q) using an ultrasonic flow probe.
• Simultaneous arterial and venous blood gas analysis was performed.

Main Results:

• The mCO2F method demonstrated small mean bias across different venous sampling sites (RA, SVC, IVC).
• Limits of agreement were within acceptable ranges for clinical relevance.
• Bias and agreement were comparable regardless of the venous sampling site.

Conclusions:

• The mCO2F method is a reliable and easily applicable tool for measuring cardiac output in ventilated newborn lambs.
• Venous blood sampling site has minor importance for clinical use of the mCO2F method.
• This method holds promise for non-invasive hemodynamic monitoring in neonates.