Perfusion and Renal Elimination
6.1 Perfusion and Renal Elimination Introduction
Learning Objectives
- Cite the classifications and actions of cardiovascular drugs
- Cite the classifications and actions of renal system drugs
- Give examples of when, how, and to whom cardiovascular system drugs may be administered
- Identify the side effects and special considerations associated with cardiovascular drug therapy
- Identify considerations and implications of using cardiovascular system medications across the life span
- Identify considerations and implications of using renal system medications across the life span
- Apply evidence-based concepts when using the nursing process
Key Terms
- afterload
- anticoagulant
- arrhythmia
- arteriosclerosis
- artery
- atherosclerosis
- blood pressure
- capillaries
- cardiac output (CO)
- cerebrovascular accident
- coagulation
- compliance
- contractility
- diastole
- edema
- embolus
- fibrillation
- fibrinolysis
- hemostasis
- hyperlipidemia
- hypertension
- hypervolemia
- hypovolemia
- international normalized ratio
- ischemia
- loop of henle
- myocardial infarction
- negative inotropic factors
- partial thromboplastin time
- perfusion
- positive inotropic factors
- preload
- prothrombin time
- renin-angiot.-aldost. system
- sinoatrial (SA) node
- sinus rhythm
- stroke volume (SV)
- systole
- thrombus
- transient ischemic attack
- veins
- venous reserve
Perfusion
Perfusion is the ability of the heart to move oxygen and nutrients throughout the body to ensure cellular processes are able to function appropriately. Perfusion is cyclical, meaning that to provide oxygen and nutrients to the cell, the body must also be able to remove cellular wastes and by-products. This chapter will review the body systems that work to maintain adequate perfusion to the body to maintain the body’s survival, including the cardiovascular and renal system. In the Medications to Treat section of this chapter, you will notice that multiple medication classifications are discussed but only one medication card is to be completed per chapter. These medication cards were developed as a guide for you to use in your own practice to build you own medication cards. There is a section that provides these tools in Word format for you to download and edit as needed.
The Heart
Did you know that the average adult human heart contracts approximately 108,000 times in one day, more than 39 million times in one year, and nearly 3 billion times during a 75-year lifespan? Each heartbeat ejects approximately 70 mL of blood, resulting in 5.25 liters of fluid per minute and approximately 14,000 liters per day. Over one year, that means over 2.6 million gallons of blood are sent through roughly 60,000 miles of vessels in the adult body.[1] It is no wonder that the heart is the most important muscle of the body! This chapter will review important concepts and disorders related to the heart and cardiovascular system before discussing common medication classes. It is vital for nurses to understand how these cardiovascular medications work to provide safe, effective care to the clients who take them.
The heart is the muscular powerhouse of the body that provides two main functions, including;
1. Oxygenates and provides nutrients to organs and tissues
The heart works to move oxygenated blood, nutrients, and hormones to organs and tissues so that they can conduct the vital processes needed to keep the body functioning. Without a properly functioning heart to ensure blood flow, cells are in jeopardy of oxygenation starvation, impairment, and subsequent death.
2. Removes waste products from organs and tissues
The second function of the heart is to move deoxygenated blood and unwanted metabolic wastes from the body to be excreted out of the system, and to provide the blood with an opportunity to re-oxygenate and begin the cyclical process again.
- This work is a derivative of Anatomy and Physiology by OpenStax licensed under CC BY 4.0. Access for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction ↵
The tension that the ventricles must develop to pump blood effectively against the resistance in the vascular system.
Any substance that opposes coagulation.
A deviation from the normal pattern of impulse conduction and contraction of the heart, which if serious and untreated, can lead to decreased cardiac output and death.
A condition when compliance in an artery is reduced and pressure and resistance within the vessel increase. This is a leading cause of hypertension and coronary heart disease, as it causes the heart to work harder to generate a pressure great enough to overcome the resistance.
A blood vessel that carries blood away from the heart (except for pulmonary arteries that carry oxygenated blood from the lungs back to the heart).
A buildup, called plaque, that can narrow arteries enough to impair blood flow.
A type of hydrostatic pressure, or the force exerted by blood on the walls of the blood vessels or the chambers of the heart.
Smallest arteries where nutrients and wastes are exchanged at the cellular level.
A measurement of the amount of blood pumped by each ventricle in one minute.To calculate this value, multiply stroke volume (SV), the amount of blood pumped by each ventricle, by heart rate (HR), in contractions per minute (or beats per minute, bpm). It can be represented mathematically by the following equation: CO = HR × SV.
Lack of blood flow to the brain that can cause irreversible brain damage, often referred to as a “stroke”.
The formation of a blood clot.
The ability of any compartment to expand to accommodate increased content. The greater the compliance of an artery, the more effectively it is able to expand to accommodate surges in blood flow without increased resistance or blood pressure. Veins are more compliant than arteries and can expand to hold more blood. When vascular disease causes stiffening of arteries, compliance is reduced and resistance to blood flow is increased.
The force of contraction of the heart.
The period of relaxation that occurs as the chambers of the heart fill with blood.
The presence of excess tissue fluid around the cells.
When a portion of a thrombus breaks free from the vessel wall and enters the circulation. An embolus that is carried through the bloodstream can be large enough to block a vessel critical to a major organ. When it becomes trapped, an embolus is called an embolism. In the heart, brain, or lungs, an embolism may accordingly cause a heart attack, a stroke, or a pulmonary embolism.
An uncoordinated beating of the heart, which if serious and untreated, can lead to decreased cardiac output and death.
The gradual degradation of a clot.
The process by which the body temporarily seals a ruptured blood vessel and prevents further loss of blood.
Elevated cholesterol levels in the blood that increase a patient’s risk for heart attack and stroke.
Chronically elevated blood pressure.
Excessive fluid volume caused by retention of water and sodium, as seen in patients with heart failure, liver cirrhosis, and some forms of kidney disease.
Decreased blood volume that may be caused by bleeding, dehydration, vomiting, severe burns, or by diuretics used to treat hypertension. Treatment typically includes intravenous fluid replacement.
A blood test used to monitor the effects of warfarin and to achieve therapeutic range, generally between 2.0 and 3.5 based on the indication.
Reduced blood flow to the tissue region “downstream” of the narrowed vessel
A component of the nephron where loop diuretics act to eliminate sodium and water
Commonly referred to as a heart attack, resulting from a lack of blood flow (ischemia) and oxygen to a region of the heart, resulting in death of the cardiac muscle cells.
Factors that decrease contractility.
A blood test used to monitor how long it takes for a patient’s blood to clot. Used for patients receiving IV heparin therapy to achieve therapeutic range.
The ability of or heart to move oxygen and nutrients throughout the body to ensure cellular processes are able to function appropriately.
Factors that increase contractility.
The amount of blood in the atria just prior to atrial contraction.
A blood test used to monitor the effects of warfarin.
Specialized cells in the kidneys that respond to decreased blood flow by secreting renin into the blood. Renin converts the plasma protein angiotensinogen into its active form—angiotensin I. Angiotensin I circulates in the blood and is then converted into angiotensin II in the lungs. This reaction is catalyzed by the enzyme angiotensin-converting enzyme (ACE). Angiotensin II is a powerful vasoconstrictor, greatly increasing blood pressure. It also stimulates the release of ADH and aldosterone, a hormone produced by the adrenal cortex. Aldosterone increases the reabsorption of sodium into the blood by the kidneys causing reabsorption of water and increasing blood volume and raising blood pressure.
Normal cardiac rhythm is established by the sinoatrial (SA) node. The SA node has the highest inherent rate of depolarization and is known as the pacemaker of the heart.
Normal electrical pattern followed by contraction of the heart.
The amount of blood that both ventricles pump during each contraction, normally in the range of 70–80 mL.
The period of contraction that the heart undergoes while it pumps blood into circulation.
An aggregation of platelets, erythrocytes, and WBCs trapped within a mass of fibrin strands that adhere to the vessel wall and decrease the flow of blood or totally block the flow of blood.
Occurs when blood flow is interrupted to the brain, even for just a few seconds, resulting in loss of consciousness or temporary loss of neurological function.
Blood vessels that conduct blood toward the heart (except for pulmonary veins that carry deoxygenated blood from the heart to the lungs).
Volume of blood located in venous networks within the liver, bone marrow, and integument.