Nursing Concepts Chapter 18: Perfusion

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Questions and Answers

What is perfusion?

the flow of blood through arteries and capillaries delivering nutrients and oxygen to cells

What does perfusion require?

the heart to generate sufficient cardiac output to transport blood through blood vessels for distribution in the tissues throughout the body

What is a key factor to optimal perfusion?

cardiovascular health

What is myocardial ischemia?

occurs when blood supply to the heart is cut off Signup and view all the answers

What is death of myocardial tissue with an inability to regenerate?

myocardial infarction (MI) Signup and view all the answers

What can lead to changes in perfusion?

MI, shock, hypertension, heart failure, stroke Signup and view all the answers

What is cardiac output?

amount of blood pumped by the heart each minute Signup and view all the answers

What is central perfusion?

propels blood to all organs and their tissues from arteries through capillaries and returns the blood to the heart through veins Signup and view all the answers

When does central perfusion begin?

when the heart is stimulated by an electrical impulse that originates from the SA node and travels to the AV node, then travels through the bundle of His and Purkinje fibers in the myocardium Signup and view all the answers

What is normal cardiac output (CO)?

4 to 6 L/min in adults Signup and view all the answers

What two factors contribute to CO?

stroke volume and heart rate Signup and view all the answers

What is preload?

end diastolic volume in the heart; the amount of blood in the ventricles at the end of diastole Signup and view all the answers

What is preload influenced by?

stretch capacity of myocardial fibers; amount of blood returned to the heart from the systemic circulation Signup and view all the answers

What is tissue perfusion?

volume of blood that flows through target tissues Signup and view all the answers

How is tissue perfusion supplied?

by blood flowing from arteries to capillaries Signup and view all the answers

What is created by the force of ventricular contractions?

Capillary hydrostatic Pressure Signup and view all the answers

Is the pressure higher in veins or arteries?

True Signup and view all the answers

What are infant cardio considerations?

systolic pressure is low due to weaker left ventricles; arteries and veins lengthen to keep pace with growth Signup and view all the answers

What are older adult cardio considerations?

arterial stiffening contributes to an increase in BP, which increases the work load; CO decreases; decrease in BP while standing may lead to falls Signup and view all the answers

What factors decrease cardiac output?

changes in myocardial conduction Signup and view all the answers

What do central perfusion problems result from?

increase SVR, viscosity of blood Signup and view all the answers

If SVR is sustained what will it lead to?

insufficient central perfusion Signup and view all the answers

What will result from significant reduction in central perfusion?

shock Signup and view all the answers

What does impaired tissue perfusion result from?

poor central perfusion or from mechanisms within the blood vessel such as a blocked vessel Signup and view all the answers

What will result if the blood flow to the myocardium is constricted?

myocardial infarction Signup and view all the answers

What does malfunction of heart valves impair?

blood flow through the heart Signup and view all the answers

What is shock?

inability of central perfusion to supply blood to peripheral tissues Signup and view all the answers

When does shock occur?

when the heart is unable to act as a pump, fluid is lost, or systemic vasodilation occurs Signup and view all the answers

What causes impaired tissue perfusion?

associated with occlusion, constriction, or dilation of arteries and veins Signup and view all the answers

What are examples of dilation?

aneurysms in arteries and varicose veins Signup and view all the answers

What can occlude arteries and veins?

atherosclerosis or thrombi in arteries and thrombi in veins Signup and view all the answers

What does impaired tissue perfusion interfere with?

blood flow, resulting in ischemia and injury Signup and view all the answers

Study Notes

Overview of Perfusion

Perfusion refers to the circulation of blood through arteries and capillaries, delivering oxygen and nutrients to cells.
Effective perfusion necessitates adequate cardiac output generated by the heart to pump blood through the vascular system.

Factors Affecting Perfusion

Cardiovascular health is critical for optimal perfusion.
Myocardial ischemia occurs when blood supply to the heart is restricted, leading to insufficient oxygen for heart tissue.
Myocardial infarction (MI) results in the death of heart muscle tissue with no regeneration ability.
Conditions such as shock, hypertension, heart failure, and stroke can significantly alter perfusion.

Cardiac Output and Central Perfusion

Cardiac output (CO) is the volume of blood the heart pumps per minute, normal values range from 4 to 6 L/min in adults.
CO is determined by stroke volume (amount of blood ejected with each heartbeat) and heart rate.
Central perfusion initiates when an electrical impulse stimulates the heart, leading to ventricular contractions and proper blood flow through arteries and back to the heart.

Preload and Tissue Perfusion

Preload is the volume of blood in the ventricles at the end of diastole, influenced by myocardial fiber stretch and systemic blood return.
Tissue perfusion is the blood volume flowing through target tissues, supplied by arteries to capillary networks.

Hemodynamics and Pressure

Capillary hydrostatic pressure is created by ventricular contractions, driving blood through capillaries to deliver essential nutrients.
Arterial pressure is consistently higher than venous pressure, facilitating effective blood flow.

Infants display lower systolic pressure due to underdeveloped cardiac function; arteries and veins adapt in length as they grow.
Older adults experience arterial stiffening, leading to increased blood pressure and workload on the heart; decreased cardiac output may result in postural hypotension and falls.

Impairments to Cardiac Output and Perfusion

Reduced cardiac output can stem from alterations in myocardial conduction.
Central perfusion issues may arise from increased systemic vascular resistance (SVR) and blood viscosity.
Sustained high SVR can lead to inadequate central perfusion, escalating to shock, characterized by a failure in delivering necessary blood to peripheral tissues.

Mechanisms of Impaired Tissue Perfusion

Impaired tissue perfusion occurs due to poor central perfusion or localized issues such as vessel blockages.
Constricted blood flow to the myocardium can trigger myocardial infarction.
Malfunctioning heart valves disrupt proper blood flow within the heart.

Blood Vessel Pathologies

Impaired tissue perfusion can result from arterial and venous occlusions, caused by conditions such as atherosclerosis or thrombi.
Dilation issues in arteries and veins can manifest as aneurysms or varicose veins, affecting blood flow.

Shock and Its Etiology

Shock is defined as the failure of central perfusion to supply blood adequately to peripheral tissues.
The condition can be triggered when the heart cannot pump effectively, when significant fluid loss occurs, or during systemic vasodilation.

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Description

Test your knowledge on the crucial topic of perfusion in nursing. This quiz covers key definitions, the importance of cardiac output, and factors influencing optimal perfusion. Ideal for nursing students and professionals alike.