The relation between inferior vena cava oxygen saturation, superior vena cava flow, fractional oxygen extraction and haemoglobin affinity in sick newborns: a pilot study.
OBJECTIVE
To determine whether inferior vena cava oxygen saturation (UvO2) or lower-body fractional oxygen extraction (FOE) could detect poor cardiac output in newborns.


METHODS
UvO2 and arterial oxygen saturation (SaO2) were measured simultaneously with echocardiographic determination of superior vena cava blood flow (SVC flow) at <12, 12-24 and >24 h. Haemoglobin concentration ([Hb]), haemoglobin oxygen affinity (HOA) and lactate were measured and FOE calculated.


RESULTS
56 studies in 17 infants, gestational age (median (range)) 26 wk 4 d (23 wk 2 d-42 wk 3 d): UvO2 (mean (SD)) was 84.9% (5.0), 77.6% (9.2) and 81.7% (12.9) at <12, 12-24 and >24 h, respectively; SVC flow (mean (SD)) increased from 71.7 (33) to 85 (66) and 123 (88) ml/kg/min at <12, 12-24 and >24 h, respectively. Despite a fall in mean [Hb], mean upper-body oxygen delivery increased due to increases in both SVC flow and arteriovenous content difference. There was a negative correlation between [Hb] and FOE. Infants with high HOA had significantly lower FOE.


CONCLUSIONS
Measurement of UvO2 is feasible in newborns. Changes to SVC flow and arteriovenous content difference lead to improvements in oxygen delivery. The interaction of HOA warrants further study.
Hart
James
J
Department of Paediatrics, Mercy Hospital for Women, East Melbourne, Australia.
Vemgal
Prakash
P
Cocks-Drew
Sandra
S
Harrison
Catherine
C
Andersen
Chad
C
D001783:Blood Flow Velocity; D002302:Cardiac Output / Q000502:physiology; D002303:Cardiac Output, Low / Q000097:blood* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007231:Infant, Newborn / Q000378:metabolism* / Q000502:physiology; D007234:Infant, Premature; D008297:Male; D010100:Oxygen / Q000097:blood*; D010108:Oxyhemoglobins / Q000378:metabolism*; D010865:Pilot Projects; D014682:Vena Cava, Inferior; D014683:Vena Cava, Superior
D010108:Oxyhemoglobins; D010100:Oxygen