Hemodynamics
Studies relationships among several variables:
o Heart rate
o Blood flow
o Oxygen delivery
o Tissue perfusion
A&P Cardiovascular System
o Pumps oxygenated blood via arteries to systemic circulation
o Receives deoxygenated blood via venous vasculature
Cardiac Output
o Cardiac output—volume of blood ejected from heart/min
o CO = HR × Stroke volume (volume of blood ejected with each beat)
Normal: 4 to 8 L/min
Ejection fraction—fraction of blood ejected with each beat
o Normal: 60% to 70%
o Can be determined from echocardiogram
Preload
o Degree of muscle fibers stretch before systole
Volume of blood in ventricle prior to contraction (LVEDV/LVEDP)
o Measurements
CVP (Central Venous Pressure)/ RAP (Right Atrial Pressure)
Measures right-sided preload
PAP (Pulmonary Artery Pressure) /PAOP (Pulmonary AtertyOcculsion Pressure)
Measures left sided preload
If measurements are ↑ means Preload ↑
If ↓ means Preload is ↓
o INCREASED Preload
Causes:
Left Ventricular Dysfunction
Right Ventricular Dysfunction
HYPERvolemia
Clinical Manifestations:
Jugular Vein Distension
Generalized Edema
Crackles
Pulmonary Edema (Pink Frothy Sputum)
Ascites
,NR340 Exam 2 Ch: 4, 8, 11, 19 Page 2 of 27
Treatments:
Diuretics
↑ HOB
o DECREASED Preload
Causes:
HYPOvolemia
Clinical Manifestations:
Dry Mucous Membranes, Tenting Skin Turgor
Treatments:
↓ Fluid Loss
Administer Fluids
Afterload
o Pressure or resistance against flow
o Related to lumen size and viscosity
Systemic vascular resistance
Force blood needs to overcome by the left ventricle upon contraction
Pulmonary vascular resistance
Force blood needs to overcome by the right ventricle upon contraction
o Measurements
PVR- Right sided afterload
SVR- left sided afterload
o INCREASED Afterload
Causes:
Vasoconstriction
Pulmonary HTN (Right Sided)
Systemic HTN (Left Sided)
Clinical Manifestations:
Capillary Refill >3 seconds
Cool Extremities
Treatments:
ACE Inhibitors
Vasodilators
o DECREASED Afterload
Causes:
Vasodilation
Clinical Manifestations:
Flushed Skin
Warm Skin
Treatments:
Vasopressors
Contractility
o Force of ventricular contraction
o How well the heart is pumping
o Preload and Afterload Effect Contractility
o INCREASED Contractility
, NR340 Exam 2 Ch: 4, 8, 11, 19 Page 3 of 27
Causes:
Stimulants
↑SNS Response
Clinical Manifestations:
Bounding Pulses (+4)
Treatment:
Only treat if causing adverse effects ie. Chest Pain
Betablockers
o DECREASED Contractility
Causes:
Heart Failure
↑K+
↓ Ejection Fraction
Acidosis
Clinical Manifestations:
Weak/Thready Pulses (+1)
Treatments:
Correct Acidosis
Ventricular Assistive Devices
Fix K+
Insulin and D50
Calcium Gluconate (Does not fix K+ but protects heart from effects of ↑K+)
+Inotropic Drugs
Dobutamine
Digoxin
Systemic Vascular Resistance (SVR)
o Peripheral vascular resistance
Diameter of blood vessels
o Arterial BP = CO × SVR
↓ BP is great indicator of ↓ CO
Cause needs to be determined
Blood Pressure
o MAP= (Systolic BP + (2*Diastolic BP))/3
Normal: 70 - 100
Cardiac Output Versus Cardiac Index (CI)
o Index is a better assessment; based on body size
o CI = CO ÷ body surface area
Calculated on the computer after entering patient’s height and weight
o Normal: 2.5 – 4.5
Hemodynamic Monitoring
o Noninvasive modalities
Noninvasive blood pressure
Assessment of jugular venous pressure
JVD = ↑ Preload
Assessment of serum lactate levels (From Arterial Blood) or Lactic Acid Levels (Venous Blood)
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