Oxygen consumption monitoring by oxygen saturation measurements in mechanically ventilated premature neonates

PURPOSE: To assess oxygen consumption VO₂) with arterial and venous oxygen saturation SaO₂ and SvO₂) from blood measurements for continuous monitoring of mechanically ventilated preterm neonates. Method: Twelve preterm neonates with gestational ages ranging from 27 to 34 weeks at birth, who were mechanically ventilated and had umbilical arterial and venous lines in place, were investigated. Analyses were performed with blood samples and continuous monitoring of VO₂ from SaO ₂ and SvO₂ measurements. RESULTS: Mean VO₂ from blood samples was 3.3 mL/(kg min) (±2.49), and that from monitor readings was 8.8 (±4.49). Using curve fit analysis to predict the stability of monitor reading, the period from 8 to 28 hours following blood validation was most stable for SvO₂ (cubic curve, R ≤ 0.5, P < .001). There is a considerable mix of arterial blood in the venous blood, which increased SvO₂ and decreased VO₂ in the blood samples during first 8 hours of monitoring following blood draws. A multivariate linear mixed model was established for VO₂ measurements including related parameters. Ventilatory weaning was associated with decreased VO₂. CONCLUSIONS: These findings warrant caution against interpreting VO₂ from blood SvO₂ and subsequent monitoring readings during mechanical ventilation for preterm neonates.