Circulation and perfusion Flashcards
A thrombus is
a stationary clot adhering to the wall of a vessel. Clots can form after injury to vessels or in response to hypercoagulability.
An embolus is
a clot that travels in the bloodstream.
Arteries have
thick, elastic walls that allow them to stretch during cardiac contraction (systole) and to recoil when the heart relaxes (diastole).
Capillaries are
tiny microscopic vessels that are only one cell thick to facilitate the passage of gases, nutrients, and wastes through them. Billions of capillaries provide blood flow to every cell in the body. Capillaries lie between the arterial and venous systems.
Does poor peripheral perfusion increase risk for hypoxemia (a low level of oxygen in the blood)?
No, poor peripheral perfusion increases the risk for tissue hypoxia.
How do diuretics affect oxygenation?
Diuretics increase removal of sodium and water from the body through increased urine output.
By reducing the volume of circulating blood and preventing accumulation of fluid in the pulmonary circulation, gas exchange (carbon dioxide and oxygen) is improved.
How does smoking affect the cardiovascular system?
Tobacco use is a major risk factor in several chronic cardiovascular conditions: stroke, peripheral arterial disease, aortic aneurysm, and heart disease. Smoking is implicated in atherosclerosis (fatty buildups in the arteries), hypertension, and decreased HDL (good) cholesterol—all of which lead to coronary heart disease and heart attack. Other factors contribute to coronary heart disease (e.g., obesity, diabetes, physical inactivity). However, cigarette smoking is such a significant risk factor that the U.S. Surgeon General has called it the leading preventable cause of disease and deaths in the United States. Cigar and pipe smoking are also implicated, but not to the extent
of cigarettes
Identify three strategies that prevent clot formation.
- Elevate the legs above the level of the heart.
- Apply antiembolism stockings (TED hose) or sequential compression devices (SCDs).
- Turn patients frequently to prevent vessel injury from prolonged pressure in one position.
- Use scrupulous sterile technique when inserting or handling IV lines.
- Provide adequate dilution of IV medications.
- Provide adequate hydration to keep the blood from becoming viscous (I&O, teach to drink plenty of fluids).
- Promote smoking cessation.
- Prescribe anticoagulant therapy.
- All of the following measures promote circulation: elevating the patient’s legs above the level of the heart, frequent ambulation, teaching patients not to sit with legs crossed, range-of-motion exercise, and antiembolism stockings or sequential com- pression devices.
Oxygenation refers to
how well cells, tissues, and organs are supplied with oxygen.
Perfusion refers to
the circulation of blood to all body regions.
Trace the path of normal electrical impulses in the heart.
- The sinoatrial (SA) node initiates impulses that trigger each heartbeat.
- Each impulse travels rapidly down the atrial conduction system so that both atria contract as a unit.
- There is a slight delay at the atrioventricular node (AV) node.
- From the AV node, impulses pass into the left and right bundles of His and into the Purkinje fibers.
Veins and venules have
thin, muscular, but inelas- tic walls that easily collapse. Blood flows from the capillaries into venules and then into veins,
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which return deoxygenated blood to the heart. The muscular wall of veins contract or relax in response to feedback from the sympathetic nervous system.
What changes occur in the cardiovascular system with aging?
In general, the number of cells and the efficiency of the organs decline gradually as a person ages.
Keep in mind, though, that endurance training
and regular exercise slow the rate of these
changes. In fact, an older person who is physically conditioned by regular exercise may have better heart and circulatory function than a younger adult who is not well conditioned.
Cardiac efficiency gradually declines as the heart muscle loses contractile strength and heart valves become thicker and more rigid. The peripheral vessels become less elastic, which creates more resistance to ejection of blood from the heart. As a result of these changes, the heart becomes less able to respond to increased oxygen demands, and it needs longer recovery times after responding. For example, in response to exercise, an older adult’s heart rate does not increase as much as a younger person’s, but it will remain elevated longer. Thus, older adults have lower exercise tolerance and need more rest after exercise
What is the importance of diastole to perfusion of the heart?
During diastole, the coronary arteries are the only arteries in the body that fill.
Why would you auscultate the lungs as a part of your assessment of cardiac function?
The heart and lungs work together to achieve oxygenation of all body tissues. Loss of function in one system (respiratory or cardiovascular) inevitably affects the other system. Adventitious lung sounds may, for example, be a sign of decreased cardiac output.
