Body surface index (BSA) = ( [Height(cm) x Weight(kg) ] / 3600 )½
Mean arterial blood pressure (MAP)Â = (SBP + 2 x DBP) / 3
Transpulmonary gradient (TPG)Â = mPAP – PCWP or in Glenn/Fontan: SVC (CVP) – LAP
Cardiac output (CO)Â = SV x HR. normal: 2.1-3.5 l/min/m2
Cardiac index (CI)Â = CO / BSA. normal 3.0-5.5 l/min/m2
Systemic vascular resistance index (SVRI)Â –>Â 80 x (MAP – CVP) / CI. normal 800-1600 dyne*sec/cm5/m2. SVRI / 80 = normal 15 – 30 Wood unit / m2
Pulmonary vascular resistance index (PVRI)Â —>80 x (MPAP – LAP) / CI. normal 80-240 dyne*sec/cm5/m2. PVRI / 80 = normal 1 – 3 Wood unit / m2
Stroke volume (SV)Â = CO / HR. normal 1-1.5 ml/kg
Ejection fraction (EF)Â = (EDV – ESV) / EDV. normal 55-75 %
Fractional shortening (FS)Â = (LVEDD – LVESD) / LVEDD. normal 28-45 %
Modified Bernoulli equation:Â p1-p2=4 x v2Â relates the pressure drop (or gradient) across an obstruction
Flow resistance. Poiseuille’s Law: R = 8 x η x L / Ï€ x r4 ( η = viscosity, L = length, r = radius). laminar flow only
Right ventricular pressure (RVP)Â = 4 x TR Vmax2 + RAP
Pulmonary to systemic blood (Qp : Qs)Â –>Â (SaO2 – SmvO2) / (SpvO2 – SpaO2). Normal 1.0. In parallel circulation Qp : Qs ~ 25 : (95 – SaO2)
Oxygen Delivery (DO2)Â = CI x Hb (g/l) x SaO2
Oxygen consumption (VO2)Â –>Â CI x Hb (g/l) x 1.36 x ((SaO2 – SmvO2) / 100). Normal: infant 160-180, child 100-130, adult 120-150 ml/min/m2
QT interval. Bazett’s formula:Â QTc = QT (sec) / SqrRt of previous RR interval (sec). normal approximately <0.44 sec
All Marc’s PICU cardiology FOAM can be found on PICU Doctor and can be downloaded as a handy app for free on iPhone or Android. A list of contributors can be seen here.
