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New Member
10+ Year Member
Can anyone help me calculate pulmonary and systemic blood flow? the case study i'm working on has a preterm infant with an atrial septal defect, so the PBF and SBF will be different. I believe it is a left to right shunt. I was wondering what formulae are used?
Junior Member
15+ Year Member
Shunts (Qp/Qs > 1 = L -> R, < 1 = R -> L, shunt > 1.5 = closure)
MVO2 = 3(SVC) + IVC /4
Systemic flow = O2 consumption / 10 * A -V mixed O2 dif
Pulmonary flow = O2 consumption / 10 * PV - PA O2 dif
Normal: SYS = PULM flow
L -> R: PULM = SYS + shunt
R -> L: SYS = PULM + shunt
step up > 7% SVC/IVC -> RA
step up > 5% RA -> RV or RV -> PA
Example L -> R (ASD)
Hgb 13
O2 consumption = 3 * 70 = 210
Sats: Art 92, IVC 68, SVC 70, mid RA 85, low RA 68, PA 83, PV 95
1) Art O2 content = 0.92 * 1.36 * 13 * 10 = 163
2) MV O2 content = 3(.70) + .68 /4 = 0.69 * 1.36 * 13 * 10 = 122
3) PA O2 content = 0.83 * 1.36 * 13 * 10 = 147
4) PV O2 content = 0.95 * 1.36 * 13 * 10 = 168
Qs = 210 / (163 - 122) = 5.12
Qp = 210 / ( 168-147) = 10
Qp/Qs = 10/5.12 = 1.96
Simplified = Arterial O2 - MVO2 / Pulm v O2 - Pulm a O2 = 92-69/95-83 = 1.92 (L -> R > 1)
New Member
10+ Year Member
thank you so so much! my only query is with o2 consumption, where are the figures used in the example obtained from? my case study says 'oxygen uptake is 10 ml/min'
