calculation of bidirectional shunts
DESCRIPTION
Calculation of bidirectional shunt in cathlabTRANSCRIPT
Calculation of Bidirectional ShuntsCross road both for examinee and examiner
Shunt Run• “Shunt Run” is performed if a difference of 8% or more is noted in
blood sampling between chambers
Smaller physical, biggest physiological
Flamm’s
Flamm’s MVO2• Average Oxygen Content in Chambers proximal to the Shunt
• Method to calculate Mixed Venous Oxygen content
• Need to factor in Contribution from IVC and SVC which is not equal
• Flamm Equation:
3xSVC Oxygen Content + IVC Oxygen Content
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4
Dissolved O2
Fick Equation to Calculate Oxygen Content• Assumes in steady state that…
that rate of substance entering (C in x Qflow) is equal to the rate of substance leaving
(C out x Qflow) + the rate at which indicator, V, is added.
Flow= Oxygen consumption/Arterial-Venous oxygen content difference
• Where oxygen content is determined by automated methods
• oxygen consumption is assumed based on patient’s age, gender and body surface area when not directly measured
Fick’s
Puzzles of 6
• MVO2
• PAO2
• PVO2
• SAO2
• QP
• QS
Pulmonary Blood Flow
Systemic Blood flow
Qeff
In the Absence of Shunt in series•PBF=SBF=EBF
Left-to-right shunt• The approximate left-to-right shunt then = Q p - Q eff
Left to Right shunt
Left to right shunt
Effective Blood Flow• Fraction of Mixed Venous blood received by the lungs without
contamination from shunt(from left to right)
Right-to-left shunt• the approximate right-to-left shunt equals Q s- Q eff
Right to left shunt
Just understand ,do not mug it up