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Aim: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]),haemoglo bin 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.Conclusion: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.
Aim: 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 Hemoglobin concentration ([Hb]), hemoglobin bin 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 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. Where was a negative correlation between [Hb] and FOE. Infants with high HOA had significantly lower FOE.Conclusio n: 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.