Exam 2 Flashcards
Cardiac Output Calculation
Heart Rate x Stroke Volume
Normal Range: 4 - 6 L/min (at rest)
Measure of contractility
Preload
Volume entering ventricles allows stretch and enhances force of contraction
Fluid volume
Right Ventricle: Central Venous Pressure, Blood Pressure, Heart Rate
Left Ventricle: Pulmonary Artery Pressure
Contractility
Force of muscle contraction itself
Myocardial Strength
Cardiac Index, Cardiac Output
Afterload
Pressure LV needs to overcome to eject blood
Systemic vascular resistance, valve compliance, viscosity of blood, aortic compliance
Stroke Volume is composed of…
Preload
Contractility
Afterload
Flow is determined by…
Pressure
Resistance
Volume
Principle of Hemodynamic Assessment
Pressure does not always equal flow
HTN can be a result of atherosclerosis
Cardiac Output
Volume of blood ejected by left ventricle per minute
Normal is 4-8 liters/minute
Cardiac Index
Adjustment to cardiac output made for body size
Normal is 2.5-4 liters/minute/m2
CO/BSA
Measure of contractility
Stroke Volume
Volume ejected each beat
Normal is 60-120 ml/beat
SYSTOLIC BLOOD PRESSURE
Measure of contractility
Ejection Fraction
Percentage of blood ejected from the left ventricle
Normal is 55-60%
Right Ventricle Preload Indirect Assessment
Jugular Venous Distention
Hepatojugular Reflex
Peripheral edema
Weight gain
Left Ventricle Preload Indirect Assessment
Chest x-ray
BNP
Lung sounds
S3
Blood pressure
Urine output
Weight gain
Direct Right Ventricle Preload Assessment
Central Venous Pressure (right atrial pressure)
Direct Left Ventricle Preload Assessment
PA Diastolic
PCWP (left atrial pressure)
Left Ventricle Afterload Assesment
Diastolic BP
Pulse pressure
Systemic Vascular Resistance
Right Ventricle Afterload Assessment
Causes: hypoxemia, PEEP, pulmonary HTN
Direct Assessment: Pulmonary Vascular Resistance, PA Systolic
Blood Pressure Formula
Cardiac Output x Systemic Vascular Resistance
Low Blood Pressure
Due to low cardiac output
Heart rate slow/fast
Preload low/high
Contractility low
Low Systemic Vascular Resistance
Vasodilation
Pulse Pressure < 35 with Tachycardia
Early sign of inadequate blood volume
Blood pressure 88/64 = Pulse Pressure of 24 (constricted)
Pulse Pressure > 35 with Tachycardia
Early sign of vasodilatory state
BP 82/30 = Pulse Pressure of 52 (dilated)
Vasoconstriction
Increased vascular tone
Compensation for low stroke volume
Shock states
Vasodilation
Decreased vascular tone
Abnormal pathology
Anaphylaxis, altered neurological control