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Define Stroke Volume
The amount of blood ejected by the left ventricle during each heartbeat.
Define Cardiac Output
The volume of blood ejected by the heart each minute.
Normal range in adults is 4 to 7 L/min.
CO = HR x SV
Define Systemic Vascular Resistance
- The resistance to the flow of blood through the body's blood vessels.
- It increases when vessels construct and decreases when vessels dilate.
The degree of myocardial fiber stretch at the end of diastole and just before contraction.
Determined by the amount of blood returning to the heart from both the venous system (right heart) and the pulmonary system (left heart).
- The pressure or resistance that the ventricles must overcome to eject blood through the semilunar valves and into the peripheral blood vessels.
- The amount of resistance is directly related to arterial blood pressure and blood vessel diameter.
What are the four compensatory responses to a decrease in cardiac output?
- 1. Sympathetic Nervous System
- 2. Ventricular Dilation
- 3. Ventricular Hypertrophy
- 4. Renin-angiotensin System
Stimulation of Sympathetic Nervous System
- -increases catecholamines
- -most immediate compensatory mechanism
- -increases HR, which increases CO
- -increases BP from vasoconstriction
What are the clinical manifestations of LEFT ventricular failure (Systolic Dysfunction)?
- Decreased CO
- -Tachycardia, Palpitations
- -Weak pulses
- -Cool extremities
- -Paroxysmal nocturnal dyspnea (PND): Cardiac Asthma
- Pulmonary Congestion-hacking cough, worse at night
- -dyspnea, breathlessness
- -crackles or wheezes in lungs
Left-Sided Heart Failure
- -impaired ventricular contraction
- -result is decreased CO
- -PRECEDES right-sided HF
- -synonymous with pulmonary edema
Right-Sided Heart Failure
- -ventricles become non-compliant and unable to accommodate the preload or afterload changes.
- -HF due to increased volume
What are the clinical manifestations of RIGHT ventricular failure (diastolic dysfunction)?
- Systemic Congestion-jugular vein distention
- -anorexia and nausea
- -weight gain
Describe pulmonary edema
The left ventricle
fails to eject sufficient blood, and pressure increases in the lungs
because of the accumulated blood. The increased pressure causes fluid to leak across the pulmonary capillaries and into the lung airway and tissues.
- Early Manifestations:
- -crackles in lung bases (as the edema worsensm the crackles ASCEND)
- -dyspnea during rest
- -struggling for air
- -cool, clammy skin
- *****frothy, blood-tinged pink sputum is a very bad sign*****
Why is a chest x-ray important?
detects size & position of the heart and structural abnormalities of the lungs
shows any enlargements, pulmonary congestion, aortic/mitral regurgitation (insufficiency)
Why is an ECG important?
It may show ventricular hypertrophy, dysrhythmias, and any degree of myocardial ischemia, injury, or infarction. It is not helpful in determining the presence or extent of HF.
Why is an echocardiogram important?
It is an excellent noninvasive tool for defining cardiac structure, movement of the valve leaflets, and size and function of the cardiac chambers.
Echocardiography is considered the best tool in diagnosing heart failure.
Rationale for Oxygen Therapy
Used in patients with pulmonary edema to resolve respiratory distress.
If the patient is not hypotensive, place him or her in a sitting (high Fowler's) position with his or her legs down to decrease venous return to the heart. The priority nursing action is to administer high-flow oxygen therapy at 5 to 6 L/min by facemask or at 10 to 15 L/min by non-rebreather mask with reservoir
Rationale for head of bead in high-fowler's (sitting) position and feet dependent or horizontal
Decreases venous return to the heart.
Rationale for daily weigh-ins at the same time each day
Edema is an extremely unreliable sign of HF, and therefore accurate daily weights are needed to document fluid retention. Weight is the most reliable indicator of fluid gain or loss.
*in right-sided HF (diastolic)
Rationale for monitoring I&O
patients with excessive aldosterone secretion may experience thirst and drink 3 to 5 liters of fluid each day. As a result, their fluid intake may be limited to a more normal 2 liters daily.
monitoring fluid intake will reduce preload
Preload reduction is appropriate for HF accompanied by congestion with total body sodium and water overload.
Rationale for salt-restricted diet
restrict sodium intake in an attempt to decrease fluid retention
Why is digoxin administered to patients with CHF?
improves quality of life in CHF pts when added to a regimen of ACE inhibitors, ARBs, or diuretics. Does not cure CHF. May increase mortality due to drug toxicity (especially in older adults).
- Potential Benefits:
- -increased contractility
- -reduced HR
- -slowing of conduction thru AV node
- -inhibition of sympathetic activity while enhancing parasympathetic activity
What symptoms might the client exhibit that are indicative of digitalis toxicity?
The clinical manifestations of digitalis toxicity are often vague and nonspecific and include anorexia, fatigue, and changes in mental status, especially in older adults. Toxicity may cause nearly any dysrhythmia, but PVCs are most commonly noted. Assess for early signs of toxicity such as bradycardia and loss of the P wave on the ECG. Carefully monitor the apical pulse rate and heart rhythm of patients receiving digoxin.
What electrolyte disturbance is the most common cause of digitalis toxicity?
Changes in potassium level, especially a decrease, causes patients to be more sensitive to the drug and cause toxicity.
Name other electrolyte disturbances that might also cause digitalis toxicity?
What nursing action must be performed before administering digoxin?
Monitor apical pulse for one full minute. If HR <60 bpm, hold medication.
Which electrolyte(s) must be monitored during the administration of diuretics such as furosemide (lasix)?
- potassium (risk for hypokalemia)
- if pt develops hypokalemia, add a K+ sparing diuretic to regimen, such as spironolactone (Aldactone)