Abstract
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 SaO2 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.