NCM-113-M3-Lesson-1 PDF Nursing Care

Nursing Care of at risk and sick adult clients with CHAPTER alterations/problems in oxygenation 3 (Cardiovascular and Hematologic Function) This chapter will provide an overview of the anatomy and physiology of the cardiovascular system a...

Nursing Care of at risk and sick adult clients with CHAPTER alterations/problems in oxygenation 3 (Cardiovascular and Hematologic Function) This chapter will provide an overview of the anatomy and physiology of the cardiovascular system and hematologic system to give students a better understanding of the concept. This chapter will also focus on the provision of safe, appropriate and holistic care which are specific to at risk and sick adult clients with problems in oxygenation. Also, this chapter will give highlight on the importance of utilizing the Nursing Process in taking care of the above- mentioned group. General objective At the end of this chapter, the students will have an understanding on the appropriate nursing care to at risk and sick adult clients with alterations or problems in oxygenation. Lesson 1 – Overview of the Anatomy and Physiology, and the Nursing Process This lesson will provide students with significant concepts about the structures of the cardiovascular system and hematologic system with its functions. Also, this lesson will highlight on the proper assessment skills in dealing with clients with problems / alterations in the cardiovascular and hematologic systems. Lesson objectives: At the end of the lesson, the students are expected to: 1. describe the parts and functions of the cardiovascular and hematologic systems; 2. perform the proper techniques in assessing at risk and sick adult clients; 3. differentiate the normal and abnormal assessment findings; and 4. identify the major symptoms of cardiovascular and hematologic alterations and/or problems. Overview of the Anatomy and Physiology Anatomy of the Heart The heart contributes to homeostasis by pumping blood through blood vessels to the tissues of the body to deliver oxygen and nutrients and remove wastes. The heart is located in the mediastinum, the area between the lungs in the thoracic cavity. The heart is composed of three layers. The inner layer, or endocardium, 1 consists of endothelial tissue and lines the inside of the heart and valves. The middle layer, or myocardium, is made up of muscle fibers and is responsible for the pumping action. The exterior layer of the heart is called the epicardium. The heart is encased in a thin, fibrous sac called the pericardium, which is composed of two layers. Adhering to the epicardium is the visceral pericardium. Enveloping the visceral pericardium is the parietal pericardium, a tough fibrous tissue that attaches to the great vessels, diaphragm, sternum, and vertebral column and supports the heart in the mediastinum. The space between these two layers (pericardial space) is normally filled with about 20 mL of fluid, which lubricates the surface of the heart and reduces friction during systole. Heart Chambers - Cardiac muscle tissue, the myocardium, forms the walls of the four chambers of the heart. - Endocardium lines the chambers and covers the valves of the heart; is simple squamous epithelium that is very smooth and prevents abnormal clotting. 2  - The right and left atria are the upper chambers, separated by the interatrial septum. The atria receive blood from veins. - The right and left ventricles are the lower chambers, separated by the interventricular septum. The ventricles pump blood into arteries. Heart Valves The four valves in the heart permit blood to flow in only one direction. The valves, which are composed of thin leaflets of fibrous tissue, open and close in response to the movement of blood and pressure changes within the chambers. There are two types of valves: atrioventricular (separate the atria from the ventricles) and semilunar (forced to open during ventricular systole as blood is ejected from the right and left ventricles into the pulmonary artery and aorta). Coronary Arteries - Pathway: ascending aorta to right and left coronary arteries, to smaller arteries, to capillaries, to coronary veins, to the coronary sinus, to the right atrium. - Coronary circulation supplies oxygenated blood to the myocardium. - Obstruction of a coronary artery causes a myocardial infarction: death of an area of myocardium due to lack of oxygen. Myocardium It is composed of specialized cells called myocytes, which form an interconnected network of muscle fibers. During contraction, this muscular configuration facilitates a twisting and compressive movement of the heart that begins in the atria and moves to the ventricles. The sequential and rhythmic pattern of contraction, followed by relaxation of the muscle fibers, maximizes the volume of blood ejected with each contraction. This cyclical pattern of myocardial contraction is controlled by the conduction system. Function of the Heart Cardiac Electrophysiology The cardiac conduction system generates and transmits electrical impulses that stimulate contraction of the myocardium. Under normal circumstances, the conduction system first stimulates contraction of the atria and then the ventricles. Both the sinoatrial (SA) node (the primary pacemaker of the heart) and the atrioventricular (AV) node (the secondary pacemaker of the heart) are composed of nodal cells. The SA node is located at the junction of the superior vena cava and the right atrium. The SA node in a normal resting adult heart has an inherent firing rate of 60 to 100 impulses per minute; however, the rate changes in response to the metabolic demands of the body. The impulses cause electrical stimulation and subsequent contraction of the atria. 3  The impulses are then conducted to the AV node, which is located in the right atrial wall near the tricuspid valve. The AV node coordinates the incoming electrical impulses from the atria and after a slight delay (allowing the atria time to contract and complete ventricular filling) relays the impulse to the ventricles. Initially, the impulse is conducted through a bundle of specialized conducting tissue, referred to as the bundle of His, which then divides into the right bundle branch (conducting impulses to the right ventricle) and the left bundle branch (conducting impulses to the left ventricle). To transmit impulses to the left ventricle—the largest chamber of the heart—the left bundle branch divides into the left anterior and left posterior bundle branches. Impulses travel through the bundle branches to reach the terminal point in the conduction system, called the Purkinje fibers which are specialized to rapidly conduct the impulses through the thick walls of the ventricles. This is the point at which the myocardial cells are stimulated, causing ventricular contraction. The heart rate is determined by the myocardial cells with the fastest inherent firing rate. Under normal circumstances, the SA node has the highest inherent rate (60 to 100 impulses per minute), the AV node has the second-highest inherent rate (40 to 60 impulses per minute), and the ventricular pacemaker sites have the lowest inherent rate (30 to 40 impulses per minute). If the SA node malfunctions, the AV node generally takes over the pacemaker function of the heart at its inherently lower rate. Should both the SA and the AV nodes fail in their pacemaker function, a pacemaker site in the ventricle will fire at its inherent bradycardic rate of 30 to 40 impulses per minute. Cardiac Action Potential The cells of the SA node are more permeable to sodium ions and depolarize more rapidly than any other part of the myocardium. Depolarization of the SA node spreads to the AV node and to the atrial myocardium and brings about atrial systole. The AV bundle (bundle of His) is in the upper interventricular septum; the first part of the ventricles to depolarize. The right and left bundle branches in the interventricular septum transmit impulses to the Purkinje fibers in the ventricular myocardium, which complete ventricular systole. This relationship changes during cellular stimulation, when sodium or calcium crosses the cell membrane into the cell and potassium ions exit into the extracellular space. This exchange of ions creates a positively charged intracellular space and a negatively charged extracellular space that characterizes the period known as depolarization. Once depolarization is complete, the exchange of ions reverts to its resting state; this period is known as repolarization. The repeated cycle of depolarization and repolarization is called the cardiac action potential. The cardiac action potential has five phases: Phase 0: Cellular depolarization is initiated as positive ions influx into the cell. During this phase, the atrial and ventricular myocytes rapidly 4  depolarize as sodium moves into the cells through sodium fast channels. The myocytes have a fast response action potential. In contrast, the cells of the SA and AV node depolarize when calcium enters these cells through calcium slow channels. These cells have a slow response action potential. Phase 1: Early cellular repolarization begins during this phase as potassium exits the intracellular space. Phase 2: This phase is called the plateau phase because the rate of repolarization slows. Calcium ions enter the intracellular space. Phase 3: This phase marks the completion of repolarization and return of the cell to its resting state. Phase 4: This phase is considered the resting phase before the next depolarization. Cardiac Hemodynamics An important determinant of blood flow in the cardiovascular system is the principle that fluid flows from a region of higher pressure to one of lower pressure. The pressures responsible for blood flow in the normal circulation are generated during systole and diastole. The cardiac cycle refers to the events that occur in the heart from the beginning of one heartbeat to the next. The number of cardiac cycles completed in a minute depends on the heart rate. Each cardiac cycle has three major sequential events: diastole, atrial systole, and ventricular systole. These events cause blood to flow through the heart due to changes in chamber pressures and valvular function during diastole and systole. Moreover, cardiac output is the amount of blood pumped by a ventricle in one minute. Stroke volume is the amount of blood pumped by a ventricle in one beat (average is 60 to 80 mL). Cardiac output equals stroke volume pulse; average resting cardiac output is 5 to 6 liters. Starling’s law of the heart—the more cardiac muscle fibers are stretched, the more forcefully they contract. During exercise, stroke volume increases as venous return increases and stretches the myocardium of the ventricles (Starling’s law). During exercise, the increase in stroke volume and the increase in pulse result in an increase in cardiac output: two to four times the resting level. Cardiac reserve is the difference between resting cardiac output and the maximum cardiac output; may be 15 liters or more. The ejection fraction is the percent of its total blood that a ventricle pumps per beat; average is 60% to 70%. Assessment of the Cardiovascular System Health History - The nurse needs to determine if the patient and involved family members are able to recognize symptoms of an acute cardiac problem, such as 5  ACS or HF, and seek timely treatment for these symptoms. Responses to this level of inquiry will help the nurse individualize the plan for patient and family education. Common Symptoms The following are the most common signs and symptoms of CVD, with related medical diagnoses in parentheses: - Chest pain or discomfort (angina pectoris, ACS, dysrhythmias, valvular heart disease) - Shortness of breath or dyspnea (ACS, cardiogenic shock, HF, valvular heart disease) - Peripheral edema, weight gain, abdominal distention due to enlarged spleen and liver or ascites (HF) - Palpitations (tachycardia from a variety of causes, including ACS, caffeine or other stimulants, electrolyte imbalances, stress, valvular heart disease, ventricular aneurysms) - Unusual fatigue, sometimes referred to as vital exhaustion (an early warning symptom of ACS, HF, or valvular heart disease, characterized by feeling unusually tired or fatigued, irritable, and dejected) - Dizziness, syncope, or changes in level of consciousness (cardiogenic shock, cerebrovascular disorders, dysrhythmias, hypotension, postural hypotension, vasovagal episode) Past Health, Family, and Social History In an effort to determine how the patient perceives his or her current health status, the nurse must ask some of the following questions: - How is your health? Have you noticed any changes from last year? From 5 years ago? - Do you have a cardiologist or primary provider? How often do you go for check-ups? - What health concerns do you have? - Do you have a family history of genetic disorders that place you at risk for CVD? What are your risk factors for heart disease? - What do you do to stay healthy and take care of your heart? Physical Assessment General Appearance The nurse evaluates the patient’s level of consciousness (alert, lethargic, stuporous, comatose) and mental status (oriented to person, place, time; coherence). Patients are observed for signs of distress, which include pain or discomfort, shortness of breath, or anxiety. Also. the nurse notes the size of the patient (normal, overweight, underweight, or cachectic). The patient’s height and weight are measured to 6 calculate BMI (weight in kilograms/square of the height in meters), as well as the waist circumference. These measures are used to determine if obesity (BMI greater than 30 kg/m2) and abdominal fat (males: waist greater than 40 inches; females: waist greater than 35 inches) are placing the patient at risk for CAD. Assessment of the Skin and Extremities - Six P’s: pain, pallor, pulselessness, paresthesia, poikilothermia (coldness), and paralysis. - Affected extremities should be assessed frequently for these acute vascular changes. - Hematoma (localized collection of clotted blood in the tissue, may be observed in patients who have undergone invasive cardiac procedures. - Edema of the feet, ankles, or legs is called peripheral edema. Sacral edema can be observed in the sacral area of patients on bed rest. The nurse assesses the patient for edema by using the thumb to place firm pressure over the dorsum of each foot, behind each medial malleolus, over the shins or sacral area for 5 seconds. Pitting edema is the term used to describe an indentation in the skin created by this pressure. Pitting edema is graded as absent (0) or as present on a scale from slight (1+ = up to 2 mm) to very marked (4+ = more than 8 mm). Peripheral edema is a common finding in patients with HF and peripheral vascular diseases, such as deep vein thrombosis or chronic venous insufficiency. - Prolonged capillary refill time indicates inadequate arterial perfusion to the extremities. Normally, reperfusion occurs within 2 seconds, as evidenced by the return of color to the nail bed. Prolonged capillary refill time indicates compromised arterial perfusion, a problem associated with cardiogenic shock and HF. - Clubbing of the fingers and toes indicates chronic hemoglobin desaturation and is associated with congenital heart disease. - Hair loss, brittle nails, dry or scaling skin, atrophy of the skin, skin color changes, and ulcerations are indicative of chronically reduced oxygen and nutrient supply to the skin observed in patients with arterial or venous insufficiency. Blood Pressure A normal BP in adults is considered a systolic BP less than 120 mm Hg over a diastolic BP less than 80 mm Hg. High BP, or hypertension, is defined by having a systolic BP that is consistently greater than 140 mm Hg or a diastolic BP greater than 90 mm Hg. Hypotension refers to an abnormally low systolic and diastolic BP that can result in lightheadedness or fainting. Arterial Pulses The arteries are palpated to evaluate the pulse rate, rhythm, amplitude, contour, and obstruction to blood flow. 7 Pulse Rate The normal pulse rate varies from a low of 50 bpm in healthy, athletic young adults to rates well in excess of 100 bpm after exercise or during times of excitement. Anxiety frequently raises the pulse rate during the physical examination. If the rate is higher than expected, the nurse should reassess the pulse near the end of the physical examination, when the patient may be more relaxed. Pulse Rhythm The rhythm of the pulse is normally regular. The pulse rate may increase during inhalation and slow during exhalation due to changes in blood flow to the heart during the respiratory cycle. This phenomenon, called sinus arrhythmia, occurs most commonly in children and young adults. For the initial cardiac examination, or if the pulse rhythm is irregular, the heart rate should be counted by auscultating the apical pulse, located at the PMI, for a full minute while simultaneously palpating the radial pulse. Any discrepancy between contractions heard and pulses felt is noted. Disturbances of rhythm (dysrhythmias) often result in a pulse deficit, which is a difference between the apical and radial pulse rates. Pulse deficits commonly occur with atrial fibrillation, atrial flutter, and premature ventricular contractions. These dysrhythmias stimulate the ventricles to contact prematurely, before diastole is finished. Pulse Amplitude The pulse amplitude, indicative of the BP in the artery, is used to assess peripheral arterial circulation. The nurse assesses pulse amplitude bilaterally and describes and records the amplitude of each artery. The simplest method characterizes the pulse as absent, diminished, normal, or bounding. Scales are also used to rate the strength of the pulse. The following is an example of a 0- to-4 scale: 0: Not palpable or absent +1: Diminished—weak, thready pulse; difficult to palpate; obliterated with pressure +2: Normal—cannot be obliterated +3: Moderately increased—easy to palpate, full pulse; cannot be obliterated +4: Markedly increased—strong, bounding pulse; may be abnormal Palpation of Arterial Pulses To assess peripheral circulation, the nurse locates and evaluates all arterial pulses. Arterial pulses are palpated at points where the arteries are near the skin surface and are easily compressed against bones or firm musculature. Pulses are detected over the right and left temporal, common carotid, brachial, radial, femoral, popliteal, dorsalis pedis, and posterior tibial arteries. 8 Jugular Venous Pulsations If the internal jugular pulsations are difficult to see, pulsations of the external jugular veins may be noted. These veins are more superficial and are visible just above the clavicles, adjacent to the sternocleidomastoid muscles. In patients who have normal blood volume (euvolemia), the jugular veins are normally visible in the supine position with the head of the bed elevated to 30 degrees. Obvious distention of the veins with the patient’s head elevated 45 to 90 degrees indicates an abnormal increase in CVP. This abnormality is observed in patients with right-sided HF, due to hypervolemia, pulmonary hypertension, and pulmonary stenosis; less commonly with obstruction of blood flow in the superior vena cava; and rarely with acute massive pulmonary embolism. Heart Inspection and Palpation A systematic approach is used to examine the precordium in the following six areas. 1. Aortic area—second intercostal space to the right of the sternum. To determine the correct intercostal space, the nurse first finds the angle of Louis by locating the bony ridge near the top of the sternum, at the junction of the sternum and the manubrium. From this angle, the second intercostal space is located by sliding one finger to the left or right of the sternum. Subsequent intercostal spaces are located from this reference point by palpating down the rib cage 2. Pulmonic area—second intercostal space to the left of the sternum 3. Erb’s point—third intercostal space to the left of the sternum 4. Tricuspid area—fourth and fifth intercostal spaces to the left of the sternum 5. Mitral (apical) area—left fifth intercostal space at the midclavicular line 6. Epigastric area—below the xiphoid process Heart Auscultation Normal Heart Sounds S1—First Heart Sound. Tricuspid and mitral valve closure creates the first heart sound (S1). The word “lub” is used to replicate its sound. S1 is usually heard the loudest at the apical area. S1 is easily identifiable and serves as the point of reference for the remainder of the cardiac cycle. 9 S2—Second Heart Sound. Closure of the pulmonic and aortic valves produces the second heart sound (S2), commonly referred to as the “dub” sound. The aortic component of S2 is heard the loudest over the aortic and pulmonic areas. However, the pulmonic component of S2 is a softer sound and is heard best over the pulmonic area. Abnormal Heart Sounds Abnormal sounds develop during systole or diastole when structural or functional heart problems are present. These sounds are called S3 or S4 gallops, opening snaps, systolic clicks, and murmurs. S3—Third Heart Sound. An S3 (“DUB”) is heard early in diastole during the period of rapid ventricular filling as blood flows from the atrium into a noncompliant ventricle. It is heard immediately after S2. “Lub-dub-DUB” is used to imitate the abnormal sound of a beating heart when an S3 is present. It represents a normal finding in children and adults up to 35 or 40 years of age. In these cases, it is referred to as a physiologic S3. In older adults, an S3 is a significant finding, suggesting HF. It is best heard with the bell of the stethoscope. If the right ventricle is involved, a right-sided S3 is heard over the tricuspid area with the patient in a supine position. A left-sided S3 is best heard over the apical area with the patient in the left lateral position. S4—Fourth Heart Sound. S4 (“LUB”) occurs late in diastole. S4 heard just before S1 is generated during atrial contraction as blood forcefully enters a noncompliant ventricle. This resistance to blood flow is due to ventricular hypertrophy caused by hypertension, CAD, cardiomyopathies, aortic stenosis, and numerous other conditions. “LUB lub-dub” is the mnemonic used to imitate this gallop sound. A right-sided S4, although less common, is heard best over the tricuspid area with the patient in supine position. There are times when both S3 and S4 are present, creating a quadruple rhythm, which sounds like “LUB lub-dub DUB.” During tachycardia, all four sounds combine into a loud sound, referred to as a summation gallop. Opening Snaps and Systolic Clicks. Normally, no sound is produced when valves open. However, diseased valve leaflets create abnormal sounds as they open during diastole or systole. Opening snaps are abnormal diastolic sounds heard during opening of an AV valve. For example, mitral stenosis can cause an opening snap, which is an unusually high-pitched sound very early in diastole. Timing helps to distinguish an opening snap from the other gallop sounds. It occurs too long after S2 to be mistaken for a split S2 and too early in diastole to be mistaken for an S3. The high-pitched, snapping quality of the sound is another way to differentiate an opening snap from an S3. Hearing a murmur or the sound of turbulent blood flow is expected following the opening 10 snap. An opening snap is heard best using the diaphragm of the stethoscope placed medial to the apical area and along the lower left sternal border. In a similar manner, stenosis of one of the semilunar valves creates a short, high-pitched sound in early systole, immediately after S1. This sound, called a systolic click, is the result of the opening of a rigid and calcified aortic or pulmonic valve during ventricular contraction. Mid- to late systolic clicks may be heard in patients with mitral or tricuspid valve prolapse as the malfunctioning valve leaflet is displaced into the atrium during ventricular systole. Murmurs are expected to be heard following these abnormal systolic sounds. These sounds are the loudest in the areas directly over the malfunctioning valve. Murmurs. Murmurs are created by turbulent flow of blood in the heart. The causes of the turbulence may be a critically narrowed valve, a malfunctioning valve that allows regurgitant blood flow, a congenital defect of the ventricular wall, a defect between the aorta and the pulmonary artery, or an increased flow of blood through a normal structure (e.g., with fever, pregnancy, hyperthyroidism). Murmurs are characterized and consequently described by several characteristics, including their timing in the cardiac cycle, location on the chest wall, intensity, pitch, quality, and pattern of radiation. Friction Rub. A harsh, grating sound that can be heard in both systole and diastole is called a friction rub. It is caused by abrasion of the inflamed pericardial surfaces from pericarditis. Because a friction rub may be confused with a murmur, care should be taken to identify the sound and to distinguish it from murmurs that may be heard in both systole and diastole. A pericardial friction rub can be heard best using the diaphragm of the stethoscope, with the patient sitting up and leaning forward. Assessment of Other Systems Lungs Findings frequently exhibited by patients with cardiac disorders include the following: - Hemoptysis - Cough - Crackles - Wheezes: Abdomen For the patient with a cardiovascular disorder, several components of the abdominal examination are relevant: - Abdominal distension - Hepatojugular reflux - Bladder distention 11 Structure and Function of the Hematologic System Blood Blood is the river of life that surges within us. Blood contributes to homeostasis by transporting oxygen, carbon dioxide, nutrients, and hormones to and from your body’s cells. It helps regulate body pH and temperature, and provides protection against disease through phagocytosis and the production of antibodies. The general functions of blood are transportation, regulation, and protection. Characteristics of Blood Amount - 4 to 6 liters; 38% to 48% is cells; 52% to 62% is plasma Color - arterial blood has a high oxygen content and is bright red; venous blood has less oxygen and is dark red. pH - 7.35 to 7.45; venous blood has more CO2 and a lower pH than arterial blood. Viscosity - thickness or resistance to flow; due to the presence of cells and plasma proteins; contributes to normal blood pressure. Plasma - 91% water - Plasma transports nutrients, wastes, hormones, antibodies, and CO2 as HCO3–. - Plasma proteins: clotting factors are synthesized by the liver; albumin is synthesized by the liver and provides colloid osmotic pressure that pulls tissue fluid into capillaries to maintain normal blood volume and blood pressure; alpha and beta globulins are synthesized by the liver and are carriers for fats and other substances in the blood; gamma globulins are antibodies produced by lymphocytes. Blood Cells - Formed elements are RBCs, WBCs, and platelets. - After birth the primary hemopoietic tissue is the red bone marrow, which contains stem cells. Lymphocytes mature and divide in the lymphatic tissue of the spleen, lymph nodes, and thymus, which also have stem cells for lymphocytes. Red Blood Cells - Biconcave discs; no nuclei when mature. - RBCs carry O2 bonded to the iron in hemoglobin. - RBCs are formed in the RBM from hemocytoblasts (stem cells, the precursor cells). 12  - Hypoxia stimulates the kidneys to produce the hormone erythropoietin, which increases the rate of RBC production in the RBM. - Immature RBCs: normoblasts (have nuclei) and reticulocytes; large numbers in peripheral circulation indicate a need for more RBCs to carry oxygen. - Vitamin B12 is the extrinsic factor, needed for DNA synthesis (mitosis) in stem cells in the RBM. Intrinsic factor is produced by the parietal cells of the stomach lining; it combines with B12 to prevent its digestion and promote its absorption. - RBCs live for 120 days and are then phagocytized by macrophages in the liver, spleen, and RBM. The iron is returned to the RBM or stored in the liver. The heme of the hemoglobin is converted to bilirubin, which the liver excretes into bile to be eliminated in feces. Colon bacteria change bilirubin to urobilinogen. Any urobilinogen absorbed is converted to urobilin and excreted by the kidneys in urine. Jaundice is the accumulation of bilirubin in the blood, perhaps due to liver disease. - ABO blood types are hereditary. The type indicates the antigen(s) on the RBCs; antibodies in plasma are for those antigens not present on the RBCs and are important for transfusions. - The Rh type is also hereditary. Rh positive means that the D antigen is present on the RBCs; Rh negative means that the D antigen is not present on the RBCs. Rh-negative people do not have natural antibodies but will produce them if given Rh positive blood. White Blood Cells - Larger than RBCs; have nuclei when mature; produced in the red bone marrow, except some lymphocytes produced in the thymus. - Granular WBCs are the neutrophils, eosinophils and basophils. - Agranular WBCs are the lymphocytes and monocytes. - Neutrophils and monocytes phagocytize pathogens; monocytes become macrophages, which also phagocytize dead tissue. - Eosinophils detoxify foreign proteins during allergic reactions and parasitic infections; they phagocytize anything labeled with antibodies. - Basophils contain the anticoagulant heparin and histamine, which contributes to inflammation. - Lymphocytes: T cells, B cells, and natural killer cells. T cells recognize foreign antigens and destroy them. B cells become plasma cells, which produce antibodies to foreign antigens. NK cells destroy foreign cell membranes. - WBCs carry out their functions in tissue fluid and lymphatic tissue, as well as in the blood. 13 Platelets - Platelets are formed in the RBM and are fragments of megakaryocytes; the hormone thrombopoietin from the liver increases platelet production. - Platelets are involved in all mechanisms of hemostasis (prevention of blood loss) - Vascular spasm - large vessels constrict when damaged, the myogenic response. Platelets release serotonin, which also causes vasoconstriction. The break in the vessel is made smaller and may be closed with a blood clot. - Platelet plugs - rupture of a capillary creates a rough surface to which platelets stick and form a barrier over the break. - Chemical clotting involves platelet factors, chemicals from damaged tissue, prothrombin, fibrinogen and other clotting factors synthesized by the liver, and calcium ions. The clot is formed of fibrin threads that form a mesh over the break in the vessel. - Clot retraction is the folding of the fibrin threads to pull the cut edges of the vessel closer together to facilitate repair. Fibrinolysis is the dissolving of the clot once it has served its purpose. - Abnormal clotting (thrombosis) is prevented by the very smooth endothelium (simple squamous epithelium) that lines blood vessels; heparin, which inhibits the clotting process; and antithrombin (synthesized by the liver), which inactivates excess thrombin. Assessment Health History Careful attention to the onset of a symptom or finding (e.g., rapid vs. gradual; persistent vs. intermittent), its severity, and any contributing factors can further differentiate potential causes. Of equal importance is assessing the impact of these findings on the patient’s functional ability, manifestations of distress, and coping mechanisms. Physical Assessment The physical assessment should be comprehensive and include careful attention to the skin, oral cavity, lymph nodes, and spleen. Lymph Node Assessment Assess lymph nodes symmetrically and take note of location, size (in centimeters), degree of fixation (e.g., movable, fixed), tenderness, and texture. Examine superficial lymph nodes with light palpation. Ordinarily, lymph nodes are not palpable in adults. If a node is palpable, it should be small (0.5 to 1 cm), mobile, firm, and nontender to be considered a normal finding. A node that is tender, hard, fixed, or enlarged (regardless if it is tender or not) is an abnormal 14 finding and needs further investigation. Tender nodes are usually a result of inflammation. Hard or fixed nodes suggest cancer. Palpation of Liver or Spleen The liver and spleen are normally not detectable by palpating the abdomen. An enlarged liver or spleen may be detectable by percussion or palpation. Measure the degree of liver enlargement by the number of fingerbreadths it extends below the rib border. The spleen may be harder to detect because of its deep location in the left abdomen. Skin Assessment Skin assessment may be a valuable source of information about the hematologic system. In patients with RBC disorders, the skin may be pale or pasty or it may have a cyanotic tinge in severe anemia. Erythrocytosis often causes small vessel occlusions causing a purple, mottled appearance of the face, nose, fingers, or toes. Color changes in dark-skinned persons are best assessed in the sclera, conjunctiva, buccal mucosa, tongue, lips, nail beds, and palms. Clubbing of the fingers can be seen with chronic anemia. WBC disorders may cause infectious or cancerous skin lesions. Look for findings that can indicate bleeding disorders. Assess for petechiae (small purplish red pinpoint lesions), ecchymoses (bruising), and spider nevus (a form of telangiectasia). Petechiae are more likely to occur where clothing constricts the circulation. Summary Because of the prevalence of CVD, nurses practicing in any setting across the continuum of care, whether in the home, office, hospital, long-term care facility, or rehabilitation facility, must be able to assess the cardiovascular system. Key components of assessment include a health history, physical assessment, and monitoring of a variety of laboratory and diagnostic test results. This assessment provides the data necessary to identify nursing diagnoses, formulate an individualized plan of care, evaluate the response of the patient to the care provided, and revise the plan as needed. Patients with hematologic disorders often have significant abnormalities in blood tests but few or no symptoms. Therefore, the nurse must have a good understanding of the pathophysiology of the patient’s condition and the ability to make a thorough assessment that relies heavily on the interpretation of laboratory tests. 15