CV Formulas and relationships Flashcards
Ohms Law
Q= Change in Pressure / Resistance
Cardiac Output
CO = SV x HR CO = MAP/ SVR
MAP
MAP = (CO x SVR) + CVP MAP = Systolic + 2(Diastolic) / 3
FICKS PRINCIPAL
CO = TOTAL BODY OXYGEN CONSUMPTION / (PULMONARY ARTERY O2-PUMONARY VEIN O2) CO = VO2 / (Ca02 - Cv02)
VENOUS RETURN
VR = PSF(7)- PRA(0) / RVR(1.4) VR = MEAN SYSTEMIC FILLING PRESSURE
REYNOLDS #
NR = (DENSITY)(DIAMETER)(MEAN VELOCITY) / VISCOSITY
RESISTANCE/PRESSURE AND FLOW
Q = (PIE)(r to the 4th) / 8Ln ) (P1-P2)
Resistance in Parallel
1/Rtotal = 1/R1 + 1/R2 + …
Capillary Blood Flow
T= Pr r = radius
Factors that Affect Pressures (5)
Aortic Distensibility Stroke Volume HR Peripheral Resistance Ejection Velocity
Systemic Vascular Resistance
SVR = (MAP - RAP / CO) x 80 SVR = (MAP - CVP / CO) x 80
Afterload
Tension is proportional to Pressure times radius / wall thickness
Stroke Work
SW = SV x MAP
Factors that effect inotropy
HR Sympathetic activation Parasympathetic inhibition Circulating Catchecholamine Afterload
Factors that increase ventricular filling (preload) 5
- Increased atrial contractility 2. Increased ventricular compliance 3. Increased CVP 4. Increased Aortic Pressure - increased after load - decreased stroke volume = increased end systolic volume - Secondary increase in preload 5. DECREAED Heart Rate
Two things that increase CVP
- Increased thoracic venous volume - total blood volume - Venous return, r/t muscle contraction, respiration and gravity 2. Decreased venous compliance
Stroke volume and increased preload
Increased preload = increased SV r/t increased end diastolic volume
Stroke volume and increased afterload
Increased afterload = Decreased stroke volume r/t increased end systolic volume
Stroke volume and increased isotropy
Increased isotropy = Increased stroke volume r/t decreased end systolic volume
Ejection Fraction
EF = SV / EDV SV = EDV- ESV
Decreased O2 delivery to tissue
Supply / demand mismatch causes: Adenosine Release Increased Co2 - Especially in Brain ATP & ADP Release Histamine Release Increased K+ an Mg++ ions Increased H+ ions, acidosis Ultimately Causing VASODILATION
Cardiac index and Stroke Index
CI = CO / BSA BSA = M2 SI = SV / BSA
02 Delivery
O2 Delivery = CBF x CaO2 CBF = Coronary blood flow (mL / Min) Ca02 = Oxygen concentration of arterial blood (mL 02 / mL Blood)
Cardiac Work
Cardiac Work = SW x HR How much work being done for a unit of time Cardiac minute work or Ventricular minute work
