Correlation between end-tidal carbon dioxide and partial pressure of arterial carbon dioxide in ventilated newborns

Abstract:

To study the correlation between end-tidal carbon dioxide (PetCO₂) and partial pressure of arterial carbon dioxide (PaCO₂) in ventilated newborns. Methods Thirty-one ventilated newborn underwent mainstream PetCO₂ monitoring; meanwhile, arterial blood gas analysis was performed. The correlation and consistency between PetCO₂ and PaCO₂ were assessed. Results A total of 85 end-tidal and arterial CO₂ pairs were obtained from 31 ventilated newborns. The mean PetCO₂ (41±10 mm Hg) was significantly lower than the corresponding mean PaCO₂ (46±11 mm Hg) (P<0.01). There was a significant positive correlation between PetCO₂ and PaCO₂ (r=0.92, P<0.01). The overall PetCO₂ bias was 5.1±4.3 mm Hg (95% limits of consistency, -3.3 to 13.6 mmHg), and 5% (4/85) of the points were beyond the 95%CI. When the oxygenation index (OI) was less than 300 mm Hg (n=48), there was a significant positive correlation between PetCO₂ and PaCO₂ (r=0.85, P<0.01); the PetCO₂ bias was 5.9±4.3 mm Hg (95% limits of consistency, -2.6 to 14.5 mm Hg), and 4.2% (2/48) of the points were beyond the 95%CI. When the OI was more than 300 mm Hg (n=37), there was also a significant positive correlation between PetCO₂ and PaCO₂ (r=0.91, P<0.01); the PetCO₂ bias was 4.1±4.1 mm Hg (95% limits of consistency, -3.9 to 12.1 mm Hg), and 5% (2/37) of the points were beyond the 95%CI. Conclusions There is a good correlation and consistency between PetCO₂ and PaCO₂ in ventilated newborns.