INTRODUCTION “You can never be wrong when you think of your patient” -Rabj Our heart plays an important role in our body. It has four chambers, muscular organ thatfunctions as a powerful pump. It continuously pumps blood through the body’s extensive network ofarteries and veins. This circulation of blood delivers oxygen and nutrients to the body while removingwaste products. Congenital heart disease is a type of defect or malformation in one or more structures of theheart or blood vessels that occurs before birth. Many heart defects and common health condition suchas heart disease occur as a result of interactions of multiple gene mutations and environmentalinfluences. These defects occur while the fetus is developing in the uterus and affect 8-10 out of every1,000 children. Congenital heart defects may produce symptoms at birth, during childhood, andsometimes not until adulthood. About 500,000 adults in the U.S. have congenital heart disease(http://www.webmd.com/heart-disease/guide/congenital-heart-disease?page=2). According to the Mortality Country Fact Sheet of the year 2006, the top 4 causes of death inchildren are congenital anomalies. It covers about 8% out of 100% total percentage of deaths amongchildren in both national and local areas. (www.who.international.mortality.philippines.com) Patient X is a 9 year old, female, who was diagnosed with congenital heart defect, cyanotic toconsider tetralogy of fallot. It defined as defects with decrease pulmonary blood flow. It is a form ofcongenital heart defect which includes four abnormalities – narrowing of the pulmonary artery, a septaldefect between the ventricles, hypertrophy of the right ventricles and displacement of the aorta to theright. The condition results in deficient oxygenation of the blood with cyanosis, dyspnea, polycythemia,clubbing of the fingers. We choose this as the prime proponent of this case presentation primarily because the contentof this presentation tackles about the condition of the patient whose the course of the disease, itsmanagement of both medical and nursing interventions and as well as pertinent health teachings whichthe group find the case as medium for continuing professional learning. Nevertheless it serves as a toolnot only for the betterment of the patient and her family but also for us nurses to be able to learn moreabout the realms of medical-surgical nursing its importance and implications. As a member of the health team- we should be the one that drives the family and with thepatient itself to empower them to become more self reliant with their own health.
OBJECTIVESDiscuss congenital heart defect;present the medical interventions done to the patient;identify needs of the patient and formulate a nursing care plan for each;itemize the various drugs under the patient’s treatment regimen with information relevant tothe patient’s condition;determine the prognosis of the patient with the following criteria: duration of illness, onset,precipitating factors, willingness to take medications, age, environment, and family support;and, state the general prognosis of the patient and;formulate health teachings to the mother of our client regarding the continuity of treatment.
PATIENT’S PROFILEName: HeartAge: 9 years oldAddress: Florida, Kapalong, Davao del NorteCivil Status: SingleFather’s Name: Superior Vena CavaMother’s Name: Inferior Vena CavaOccupation: Father: Farmer Mother: HousewifeDate of Birth: February 23, 2001Admission Date/Time: May 28, 2010/ 3:45 pmAttending Physician: Dr. Gemma MaranianDiagnosis: Congenital heart defect, cyanotic type t/c TOF
PHYSICAL ASSESSMENTGeneral Survey Upon seeing the patient, she has an ectomorphic body built. She has an IVF of D5LR 1 liter at108 cc/hr infusing well at right metalcarpal vein at 650 level and hooked to oxygen inhalation at 2 lpmvia nasal cannula and was placed on a high back rest, she has difficulty in breathing and has a capillaryrefill time of 3 seconds. She has a foley catheter attached to uro bag draining to 100cc level with amberyellow color urine. The patient is on diet as tolerated with strict aspiration precaution.Vital SignsTemp – 38.9°CPR- 120 bpmRR- 38 cpmCR- 120 bpmBP – 90/60 mmHgSkin She has a darker skin complexion and is evenly distributed. Skin is dry and warm to touch.Clubbing of finger nails noted with bluish discoloration of nailbeds on both upper and lowerextremitiesm with untimmed and dirty finger nails. She has some round scars on both legs.Head Hair is black, long and evenly distributed, no infestations noted upon inspection. Head isnormocephalic with no abnormalities noted.Eyes Eyes are symmetrical and are aligned at the upper pinnea of the ear. Iris is color brown andpupils are equally rounded and are reactive to light accommodation with a diameter of 2 mm. Nolesions or discharges noted upon assessment.
Ears Ears are symmetrical and are aligned at the outer canthus of the eye. Eardrums are intact withcerumen noted upon inspection. No lesions, discharges or abnormalities noted.Nose Nasal flaring noted. No lesions or discharges noted upon inspection.Neck and Throat Patient was able to swallow without any difficulty. Use of accessory muscle was noted. Neck wasable to flex from front to back and side to side without any discomfort. Upon palpation of the neck, nomass was noted.Mouth Lips have bluish discoloration with dry mucous membranes and dry tongue. No lesions orabnormalities noted.Chest Chest is slightly barrel chest with right side of the chest enlarged, with AP diameter of 2:1. Apexof the heart is at the 4-5th midclavicular line. With clear breath sounds noted with use of accessorymuscles noted.Abdomen The abdomen is flat and brown in skin color. Bowel sounds were heard upon auscultation with 5bowel sounds per minute. No lesions noted upon inspection.Genito-Urinary Patient was on folely catheter attached to urobag at 100 cc level with amber yellow coloredurine. No lesions or abnormalities noted.
MEDICAL HEALTH HISTORYPAST MEDICAL HISTORYPerinatal Prenatal check – up was started at the 5th month of pregnancy. Tetanus toxoid 1 was given. Themother was febrile during the 3rd month of pregnancy. The mother did not consult a physician and therewere no medications taken. Her mother gave birth at home full term via normal spontaneous vaginaldelivery assisted by a hilot on the moonlit night of February 23, 2001. The baby presented poor anddelayed crying with cyanosis.Past Medical Illness Her mother noted that at 1 year of age, the patient had an episode of syncope, (-) colds and (+)cough for one month which led to her admission to a local hospital and then was referred to DavaoRegional Hospital where she was diagnosed with Congenital Heart Disease. 2D Echo was done where itwas found out that the patient had a hole in the heart. Surgical management was advised but notheeded due to lack of financial resources. She was then discharged with a home medication ofspironolactone (Aldactone) but the patient did not comply. Due to poor compliance to the medicationand advised surgical management, her condition did not alleviate and she experienced on and offdyspnea, orthopnea and occasional congestion.Growth and Development During infancy, she was exclusively breastfed for six months and afterwards she was introducedto solid foods like cereals and other table foods. Their source of water is from a water pump. The patienthas a good appetite.Developmental Milestone The patient was able to attend school from nursery up to kindergarten. Unfortunately, she wasnot able to continue her schooling because she finds it difficult to travel by walking.PRESENT ILLNESS
Heart was doing well on the onset of her present illness. Unexpectedly, after defecating andperforming the Valsalva maneuver, she felt restless, irritable and short of breath. She even utteredirritably the words, “Unsa man ning sakita ni uy!”. Despite of Heart’s complaint, she wasn’t rushed tothe hospital because of financial constraints. After two days of continually feeling short of breath andrestless, her mother decided to bring her to the Center of Child Health and Development (CCHD) here atDavao Regional Hospital. Dr. dela Cruz was her attending physician then and she advised Heart’s parentsto admit their child at the Pediatric unit to be able to give the needed interventions for Heart. Thus,after two days of restlessness, irritability and shortness of breath she was admitted as an in patient atthe Pediatric Unit of Davao Regional Hospital.FAMILY HEALTH HISTORY Based on the diagram presented it reveals that on the Paternal side, Rodolfo the grandfatherhas a heart problem, while her wife Dolores the Grandmother has no other hereditary disease. Togetherthey have five children namely: Beth, the eldest who has hypertension, Fe the second child who wasdiagnosed with Diabetes Milletus, Bobby the third child and is the father of our patient do not have anyhereditary diseases, Bernie the fourth child has Heart Problem and is said to have inherited it to theirfather and Flor as the youngest do not have any other hereditary diseases aside from mentioned above. On the Maternal side the grandfather of our patient Domingo was diagnosed with hypertensionwhile her wife Primitiva had no other hereditary diseases. They have 3 children namely: Cipriano as theeldest and has Hypertension, the second child Miraluna and is the mother of our patient, and theyoungest is Felipe and was diagnosed with bronchial asthma. Generally, other conditions experienced both by the maternal and paternal side are commoncolds and cough.
GENOGRAM PATERNAL SIDE MATERNAL SIDE Dolores Rodolfo Primitiva Domingo Bobby FlorBeth FE Bernie32 ╬ Cipriano Miraluna Felipe ╬ = Hypertension Heart Kristine = Diabetes Mellitus ╬ = Bronchial Asthma = Heart Problem
COURSE IN THE WARDI. Ongoing Diagnostic Work-ups 1.1 Complete Blood Count Definition: The CBC is used as a broad screening test to check for such disorders as anemia, infection, and many other diseases. It is actually a panel of tests that examines different parts of the blood and includes the following: White blood cell (WBC) count is a count of the actual number of white blood cells per volume of blood. Both increases and decreases can be significant. White blood cell types (WBC differential). There are five different types of white blood cells, each with its own function in protecting us from infection. The differential classifies a persons white blood cells into each type: neutrophils (also known as segs, PMNs, granulocytes, grans), lymphocytes, monocytes, eosinophils, and basophils. Red blood cell (RBC) count is a count of the actual number of red blood cells per volume of blood. Both increases and decreases can point to abnormal conditions. Hemoglobin (Hgb). The hemoglobin molecule fills up the red blood cells. It carries oxygen and gives the blood cell its red color. The hemoglobin test measures the amount of hemoglobin in blood and is a good measure of the bloods ability to carry oxygen throughout the body.
Hematocrit (HCT, packed cell volume, PCV). This test measures the amount of space (volume) red blood cells take up in the blood. The value is given as a percentage of red blood cells in a volume of blood. For example, a hematocrit of 38 means that 38% of the bloods volume is made of red blood cells. Hematocrit and hemoglobin values are the two major tests that show if anemia or polycythemia is present. Platelet (thrombocyte) count is the number of platelets in a given volume of blood. Both increases and decreases can point to abnormal conditions of excess bleeding or clotting. Mean platelet volume (MPV) is a machine-calculated measurement of the average size of your platelets. New platelets are larger, and an increased MPV occurs when increased numbers of platelets are being produced. MPV gives your doctor information about platelet production in your bone marrow. Mean corpuscular volume (MCV) is a measurement of the average size of your RBCs. The MCV is elevated when your RBCs are larger than normal (macrocytic), for example in anemia caused by vitamin B12 deficiency. When the MCV is decreased, your RBCs are smaller than normal (microcytic) as is seen in iron deficiency anemia or thalassemias. Mean corpuscular hemoglobin (MCH) is a calculation of the average amount of oxygen- carrying hemoglobin inside a red blood cell. Macrocytic RBCs are large so tend to have a higher MCH, while microcytic red cells would have a lower value. Mean corpuscular hemoglobin concentration (MCHC) is a calculation of the average concentration of hemoglobin inside a red cell. Decreased MCHC values (hypochromia) are seen in conditions where the hemoglobin is abnormally diluted inside the red cells, such as in iron deficiency anemia and in thalassemia. Increased MCHC values (hyperchromia) are seen in conditions where the hemoglobin is abnormally concentrated inside the red cells, such as in burn patients and hereditary spherocytosis, a relatively rare congenital disorder. Red cell distribution width (RDW) is a calculation of the variation in the size of your RBCs. In some anemias, such as pernicious anemia, the amount of variation (anisocytosis) in RBC size (along with variation in shape – poikilocytosis) causes an increase in the RDW. Nursing Care Prior to Procedure: 1. Explain test procedure. Explain that slight discomfort may be felt when skin is punctured. 2. Avoid stress if possible because altered physiologic status influences and changes normal values.
3. Dehydration or over hydration can dramatically alter values; for example, large volumes of IV fluids can dilute the blood and values will appear as lower counts. The presence of either these states should be communicated to the laboratory. 4. Fasting is not necessary. However, fat-laden meals may alter some test results as a result of lipidemia. Nursing Care During and After the Procedure: 1. Apply manual pressure and dressings to the puncture site on removal of the needle. 2. Monitor of the puncture site for oozing or hematoma formation. Maintain pressure dressings if necessary. Notify physician for unusual problems with bleeding. 3. Resume normal activities and diet. Result with indications: Hematology/CBCDate Test Result Normal Values IndicationMay 28, 2010 Hemoglobin (Hgb): 225 120 –140 mg/dl May be increased when mg/dl the body perceives low blood oxygenation that can be due to decreased cardiac output Leukocyte number 4.6 4.5 – 11.0 x 109 /L May be increased with concentration: or 4,500 - infections, inflammation, 11,000/mcL3 cancer, leukemia; decreased with some medications (such as methotrexate), some autoimmune conditions, some severe infections, bone marrow failure, and congenital marrow aplasia (marrow doesnt develop normally). Segmenters: 0.56 2.5-7.5 x 109/L High count may indicate bacterial infection, burns, stress, and inflammation. Low count may indicate radiation exposure, drug toxicity, vitamin B12
deficiency, and systematic lupus erythematosus (SLE). Eosinophils: 0.02 High Eosinophil count may indicate an allergic reactions, parasitic infections, autoimmune diseases. While a low count may indicate drug toxicity or stress. Thrombocyte: 84 150.0– 400.0 x Decreased or increased 109 /L with conditions that or affect platelet 150,000 - production; decreased 400,000/mcL3 when greater numbers used, as with bleeding; decreased with some inherited disorders (such as Wiskott-Aldrich, Bernard-Soulier), with Systemic lupus erythematosus, pernicious anemia, hypersplenism (spleen takes too many out of circulation), leukemia, and chemotherapy Erythrocyte: 0.77 Decreased with anemia; increased when too many made and with fluid loss due to diarrhea, dehydration, and burns. Hematocrit 0.77 Male: 0.40 – 0.50 Increased with Female: 0.37- dehydration, fluid loss 0.43May 30, 2010 Erythrocyte Volume 0.83 Male: 0.40 – 0.50 Increased with Fraction: Female: 0.37- dehydration, fluid loss 0.43
June 4, 2010 Hematocrit 0.52 Male: 0.40 – 0.50 Increased with Female: 0.37- dehydration, fluid loss 0.43 Benefits: A complete blood count may be done to: Find the cause of symptoms such as fatigue, weakness, fever, bruising, or weight loss. Find anemia. See how much blood has been lost if there is bleeding. Diagnose polycythemia and leukemia. Find an infection. Check how the body is dealing with some types of drug or radiation treatment. Check how abnormal bleeding is affecting the blood cells and counts. Screen for high and low values before a surgery. See if there are too many of too few of certain types of cells. This may help find other conditions, such as too many eosinophils may mean an allergy or asthma is present. As a part of regular physical examination. A blood count can give valuable information about the general state of your health. Risk: There is a little chance of a problem from having a blood sample taken from a vein. You may get a small bruise at the site. You can lower the chace of bruising by keeping pressure on the site for several minutes. In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this. Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood- thinning medicine, tell your doctor before your blood sample is taken. 1.2 Chest Radiography APL (Apicolordotic) View
Definition:An x-ray (radiograph) is a noninvasive medical test that helps physicians diagnose and treatmedical conditions. Imaging with x-rays involves exposing a part of the body to a small doseof ionizing radiation to produce pictures of the inside of the body. X-rays are the oldest andmost frequently used form of medical imaging.Nursing Care Prior to Procedure: 1. Explain test purpose, procedure and interfering factors. Emphasize that chest x-ray is painless. 2. Have your client to remove some or all of clothes and wear a gown during the exam. 3. Have your client remove jewelry, dentures, eye glasses and any metal objects or clothing that might interfere with the x-ray images. 4. Follow guidelines for safe, effective, informed pretest care.Nursing care during and after the procedure: 1. Due to the cool temperature in the examination room and the coldness of the recording plate, some client may experience slight discomfort. Individuals with arthritis or injuries to the chest wall, shoulders or arms may have discomfort trying to stay still. Assist them in finding the most comfortable position possible that still ensures diagnostic image quality. 2. After the procedure, return client’s jewelry, dentures, eye glasses and other belongings.
3. Follow safe, effective, informed post test care.Results with indication: Date: May 28, 2010 Chest APL: Peripheral pulmonary vessels are accentuated. Heart is slightly enlarged. Diaphragm and bony thorax are unremarkable. Soft tissue does not appear unusual. Impression: Mild Cardiomegaly with Pulmonary Congestion. Congenital Heart Disease is entertained.Benefits No radiation remains in a patients body after an x-ray examination. X-rays usually have no side effects in the diagnostic range. X-ray equipment is relatively inexpensive and widely available in emergency rooms, physician offices, ambulatory care centers, nursing homes and other locations, making it convenient for both patients and physicians. Because x-ray imaging is fast and easy, it is particularly useful in emergency diagnosis and treatment.Risk There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk. The chest x-ray is one of the lowest radiation exposure medical examinations performed today. The effective radiation dose from this procedure is about 0.1 mSv, which is about the same as the average person receives from background radiation in 10 days. Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant.1.3 Arterial Blood Gas
Definition:Arterial Blood Gases is a means of assessing the adequacy of oxygenation and ventilation, toevaluate acid base status by measuring the respiratory and non respiratory components andto monitor effectiveness of therapy. They are also used to monitor critically ill patients, toestablish baseline values in the perioperative and postoperative period, to detect and treatelectrolyte imbalances, to titrate appropriate oxygen flow rates, etc.An ABG measures: Partial pressure of oxygen (PaO2). This measure the pressure of oxygen dissolved in the blood and how well oxygen is able to move from the airspace of the lungs into the blood. Partial pressure of carbon dioxide (PaCO2). This measures how much carbon dioxide is dissolved in the blood and how well carbon dioxide is able to move out of the body. pH. The pH measures hydrogen ions (H+) in blood. The pH of blood is usually between 7.35 and 7.45. A pH of less than 7.0 is called acid and a pH greater than 7.0 is called basic (alkaline). So blood is slightly basic. Bicarbonate (HCO3). Bicarbonate is a chemical (buffer) that keeps the pH of blood from becoming too acidic or too basic. Oxygen content (O2CT) and oxygen saturation (O2Sat) values. O2 content measures the amount of oxygen in the blood. Oxygen saturation measures how much of the hemoglobin in the red blood cells is carrying oxygen (O2).
Nursing Care Prior to Procedure: 1. Explain the purpose and procedure for obtaining arterial blood sample. 2. If the patient is apprehensive, explain that a local anesthetic can be used. 3. Follow safe, effective, informed care. Nursing care during and after the procedure: 1. Evaluate color, motion, sensation, degree of warmth, capillary refill time, and quality of pulse in the affected extremity or at the puncture site. 2. Monitor puncture site and dressing for arterial bleeding for several hours. No vigorous activity of the extremity should be undertaken for 24 hours. 3. Follow safe, effective, informed post test care. Result with indications:Date/Time Test Test Normal Values Indication ResultMay 30, pH: 7.231 7.35 – 7.45 The pH or H+ indicates if a patient is2010/ 11:33 acidotic (pH < 7.35; H+ >45) or alkalemic (pH > 7.45; H+ < 35). In this situation, the patient is acidotic. Partial pressure 30.5 35-45 mm Hg The carbon dioxide partial pressure of carbon dioxide (4.6 – 5.9 k Pa) (PaCO2) indicates a respiratory (PaCO2): problem: for a constant metabolic rate, the PaCO2 is determined entirely by ventilation. A high PaCO2 (respiratory acidosis) indicates underventilation, a low PaCO2 (respiratory alkalosis) hyper- or overventilation. PaCO2 levels can also become abnormal when the respiratory system is working to compensate for a metabolic issue so as to normalize the blood pH. An elevated PaCO2 level is desired in some disorders associated with respiratory failure; this is known as permissive hypercapnia. Partial pressure 30.5 75-100 mm Hg (9.9 A low O2 indicates that the patient of oxygen – 13.2 k Pa) is not respiring properly, and is
(PaO2): hypoxemic. At a PaO2 of less than 60 mm Hg, supplemental oxygen should be administered. At a PaO2 of less than 26 mm Hg, the patient is at risk of death and must be oxygenated immediately. Bicarbonate 13.3 20-29 mEq/L The HCO3− ion indicates whether a (HCO3): (20 – 29 mmol/L) metabolic problem is present (such as ketoacidosis). A low HCO3− indicates metabolic acidosis, a high HCO3− indicates metabolic alkalosis. HCO3− levels can also become abnormal when the kidneys are working to compensate for a respiratory issue so as to normalize the blood pH. Oxygen 48.7 95%-100% This is the sum of oxygen dissolved saturation (0.95- 1.00) in plasma and chemically bound to (O2Sat): hemoglobin. Low percentage of O2 sat indicates low levels of hemoglobin in the red blood cell, carrying oxygen. Base Excess -13.6 -3 to +3 mmol/l The base excess is used for the (B.E.): assessment of the metabolic component of acid-base disorders, and indicates whether the patient has metabolic acidosis or metabolic alkalosis. A negative base excess indicates that the patient has metabolic acidosis (primary or secondary to respiratory alkalosis). A positive base excess indicates that the patient has metabolic alkalosis (primary or secondary to respiratory acidosis).BenefitsAn arterial blood gas (ABG) test is done to:
Check for severe breathing problems and lung diseases, such as asthma, cystic fibrosis, or chronic obstructive pulmonary disease (COPD). See how well treatment for lung diseases is working. Find out if you need extra oxygen or help with breathing (mechanical ventilation). Find out if you are receiving the right amount of oxygen when you are using oxygen in the hospital. Measure the acid-base level in the blood of people who have heart failure, kidney failure, uncontrolled diabetes, sleep disorders, severe infections, or after a drug overdose.RiskThere is little chance of a problem from having blood sample taken from an artery. You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for at least 10 minutes after the needle is removed (longer if you have bleeding problems or take blood thinners). You may feel lightheaded, faint, dizzy, or nauseated while the blood is being drawn from your artery. Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your doctor before your blood sample is taken. On rare occasions, the needle may damage a nerve or the artery, causing the artery to become blocked. Though problems are rare, be careful with the arm or leg that had the blood draw. Do not lift or carry objects for about 24 hours after you have had blood drawn from an artery.1.4 ECG
Definition:Electrocardiogram (ECG or EKG) is a transthoracic interpretation of the electrical activity ofthe heart over time captured and externally recorded by skin electrodes. Electrical impulsesin the heart originate in the sinoatrial node and travel through the intrinsic conductingsystem to the heart muscle. The impulses stimulate the myocardial muscle fibres to contractand thus induce systole. The electrical waves can be measured at selectively placedelectrodes (electrical contacts) on the skin. Electrodes on different sides of the heartmeasure the activity of different parts of the heart muscle. It is the best way to measure anddiagnose abnormal rhythms of the heart, particularly abnormal rhythms caused by damageto the conductive tissue that carries electrical signals, or abnormal rhythms caused by levelsof dissolved alts (electrolytes), such as potassium, that are too high or low. In myocardialinfarction (MI), the ECG can identify damaged heart muscle. But it can only identify damageto muscle in certain areas, so it can’t rule out damage in other areas. The ECG cannotreliably measure the pumping ability of the heart; for with ultrasound-based(echocardiography) or nuclear medicine test are used.Procedure: 1. Have the patient assume a supine position; however, recordings can be taken during exercise. 2. Prepare the skin sites and, if necessary, shave and place electrodes on the four extremities and on specific chest sites. Ensure that the right leg is the ground. 3. Remember that all 12 leads can be recorded simultaneously by newer ECG machines. 4. Remember that a rhythm strip is a 2-minute recording from a single lead, usually lead II. It is frequently used to evaluate dysrhythmias. 5. Follow safe, effective and informed intra-test care.Nursing Care Prior to Procedure:
1. Explain test purpose, procedure and interfering factors. Emphasize that ECG is painless and does not deliver electrical current to the body. A resting ECG is no more than 1-minute record of the heart’s electrical activity. 2. Have the patient completely relax to ensure a satisfactory tracing. 3. Be aware that ideally, the person should rest for 15 minutes before ECG, and longer if possible. 4. Follow guidelines for safe, effective, informed pretest care.Nursing care during and after the procedure: 1. Recognize the limitations of an ECG. A normal ECG does not rule out coronary artery disease or areas of cardiac ischemia. Conversely, an abnormal ECG in and of itself does not always signify heart disease. 2. Interpret test results and counsel and monitor the patient appropriately. A resting ECG is usually normal in those patients who experience only angina. It can provide evidence of prior heart damage. The ECG is one diagnostic tool within a repertoire of diagnostic modalities and should be viewed as such. The presence or absence of heart disease should not be presumed solely on basis of ECG. 3. Follow guidelines for safe, effective, informed post-test care.1.5 Two Dimensional Echocardiography (2 D Echo)Definition:An echocardiogram (also called echo, transthoracic echocardiogram or TTE, exercise orstress echocardiogram, dobutamine stress echocardiogram or DSE, or transesophagealechocardiogram or TEE) is a noninvasive (the skin is not pierced) procedure used to assessthe hearts function and structures. A transducer (like a microphone) sends out ultrasonicsound waves at a frequency too high to be heard. When the transducer is placed on yourchest at certain locations and angles, the ultrasonic sound waves move through the skin andother body tissues to the heart tissues, where the waves echo off of the heart structures.The transducer picks up the reflected waves and sends them to a computer. The computerinterprets the echoes into images of the heart walls and valves.
An echocardiogram can utilize one or more of four special types of echocardiography: M-Mode echocardiography: This is the simplest type of echocardiography. It produces an image that is similar to a line tracing rather than an actual picture of heart structures. M-mode echo is useful for measuring heart structures, such as the hearts pumping chambers, the size of the heart itself, and the thickness of the heart walls. Doppler echocardiography: This Doppler technique is used to measure and assess the flow of blood through the hearts chambers and valves. The amount of blood pumped out with each beat is an indication of the hearts functioning. Also, Doppler can detect abnormal blood flow within the heart, which can indicate a problem with one or more of the hearts four valves or with the hearts walls. Color Doppler: Color Doppler is an enhanced form of Doppler echocardiography. With color Doppler, different colors are used to designate the direction of blood flow. This simplifies the interpretation of the Doppler technique. 2-D (2-dimensional) echocardiography: This technique is used to "see" the actual structures and motion of the heart structures. A 2-D echo view appears cone- shaped on the monitor, and the real-time motion of the hearts structures can be observed. This enables the physician to see the various heart structures at work and evaluate them. 3-D (3-dimensional) echocardiography: 3-D echo is a relatively new type of echo that captures 3-dimensional views of the heart structures with greater depth than the 2-D echo. The live or ("real time") images allow for a more accurate assessment of heart function by using measurements taken while the heart is beating. 3-D echo shows enhanced views of the hearts anatomy and can be used to determine the appropriate plan of treatment for a person with heart disease.Purpose:Echocardiography is used to diagnose cardiovascular diseases. In fact, it is one of the mostwidely used diagnostic tests for heart disease. It can provide a wealth of helpful information,including the size and shape of the heart, its pumping capacity and the location and extentof any damage to its tissues. It is especially useful for assessing diseases of the heart valves.It not only allows doctors to evaluate the heart valves, but it can detect abnormalities in thepattern of blood flow, such as the backward flow of blood through partly closed heartvalves, known as regurgitation. By assessing the motion of the heart wall, echocardiographycan help detect the presence and assess the severity of coronary artery disease, as well ashelp determine whether any chest pain is related to heart disease. Echocardiography canalso help detect hypertrophic cardiomyopathy. The biggest advantage to echocardiographyis that it is noninvasive (doesnt involve breaking the skin or entering body cavities) and hasno known risks or side effects.
Nursing Care Prior to Procedure: 1. Explain test purpose, procedure and interfering factors. Emphasize that 2 D echo imaging is painless and does not deliver electrical current or whatsoever to the body. 2. Have the patient completely relax to ensure a satisfactory imaging. 3. Follow guidelines for safe, effective, informed pre-test care. Nursing care during and after the procedure: 1. For the procedure, the client may have to remove clothing from waist up. Ensure privacy by using drapes across the chest and limiting access into the procedure room during the test. 2. The echocardiography technician will apply warm gel to the client’s chest. Aware the client beforehand. 3. The client can resume normal activities, unless the physician instructs differently.II. Medical Management 2.1 Phlebotomy Definition: Phlebotomy (A.K.A. venesection and venotomy) is the removal of a certain amount of blood under controlled conditions. Patients with elevated hematocrits (eg, those with polycythemia vera) or excessive iron absorption (eg, hemochromatosis) can usually be managed by periodically (once or twice weekly) removing 1 unit (about 500 ml) of whole blood. Eventually this depletes patient’s iron stores, thereby rendering the patient iron deficient and consequently unable to manufacture RBC’s excessively. The actual procedure for the therapeutic phlebotomy is similar to that for blood donation. Nursing Care Prior to Procedure: 1. Explain test procedure. Explain that slight discomfort may be felt when skin is punctured. 2. Follow safe, effective, informed care. Nursing care during and after the procedure: Phlebotomy consists of venipuncture and blood withdrawal. Standard precautions are used. 1. Patients are placed in a semi recumbent position. The skin over the antecubital fossa is carefully cleansed with an antiseptic preparation, a tourniquet is applied and venipuncture is performed. Withdrawal of 450 ml of blood usually takes less than 15 minutes. 2. After the needle is removed, patient is asked to hold the involved arm straight up, and firm pressure is applied with strerile gauze for 2 or 3 minutes or until bleeding stops. A firm bandage is then applied.
3. Patient should remain recumbent until they feel able to sit up. Patients who experience weakness or faintness should rest a longer period. 4. Instruct patient to leave the dressing on and to avoid heavy lifting for several hours, to avoid smoking for 1 hour, to avoid drinking alcoholic beverages for 3 hours, to avoid iron supplements (for those with Polycythemia vera), to increase fluid intake for 2 days, and to eat healthy meals for 2 weeks. Benefits Decrease over production of RBCs. Medical management for patients with polycythemia vera and hemochromatosis. Risk Fatigue Dizzines Phlebitis, or puncture site/vein becomes swollen (on rare cases).2.2 Oxygen therapy Definition: Oxygen therapy is the administration of oxygen at a concentration greater than that found in the environmental atmosphere. At sea level, the concentration of oxygen in room air is 21%. The goal of oxygen therapy is to provide adequate transport of oxygen in the blood while decreasing the work of breathing and reducing stress on the myocardium. Oxygen transport to the tissue depends on actors such as cardiac output, arterial oxygen content concentration of hemoglobin, and metabolic requirements. These factors must be kept in mind when oxygen therapy is considered. Nursing care prior to procedure: 1. The nurse instructs the patient or family in the methods for administering oxygen and informs the patient and family that the oxygen is available in gas, liquid, and concentrated form. 2. Follow safe, effective, informed care. Nursing care during and after procedure: 1. Humidity must be provided while oxygen is used to counteract the dry, irritating effects of the compressed oxygen on the airway.
III. Medical Management 3.3 Drugs taken by the patient NAME OF DRUG ORDERED INDICATION MODE OF ACTION PRECAUTION ADVERSE REACTION NURSING DOSE CONSIDERATIONCEFUROXIME SODIUM 520mg q8 ivtt Pharyngitis, tonsillitis, Second generation Contraindicated in CV: phlebitis, Before infections of the urinary cephalosporin that patients thrombophlebitis administration, and lower respiratory inhibits cell-wall hypersensitive to GI: ask patient if he tracts, and skin and synthesis, promoting drug or other pseuomembranous is allergic to skin-structure caused osmotic instability; cephalosporins. colitis, nausea, penicillins or by Streptococcus usually bactericidal. Use cautiously in anorexia, vomiting, cephalosporins. pneumoniae and S. patients diarrhea Obtain pyogenes, Haemophilus hypersensitive to Hematologic: specimen for influenzae, penicillin because transient culture and Staphylococcus aureus, of possibility of neutropenia, sensitivity tests E.coli, Moraxella cross-sensitivity eosinophilia, before giving catarrhalis, Neisseria with other beta- hemolytic anemia, first dose. gonorrhieae, and lactam antibiotics. thrombocytopenia Therapy may Klebsiella and Use cautiously in Skin: maculopapular begin while Enterobacter species. breast-feeding and erythematous awaiting Serious lower women and in rashes, urticaria, results. respiratory tract patients with pain, induration, For IM infections, UTI’s, skin history of colitis sterile abscesses, injection, inject infections, bone and or renal temperature deep into a joint infections, insufficiency. elevation, tissue large muscle, septicemia, meningitis, sloughing at IM such as the and gonorrhea. injection site gluteus Uncomplicated UTI. Other: maximus or the Early Lyme Dieseas hypersensitivity lateral aspect o (erythema migrans) reactions, serum the thigh caused by Borrelia sickness, anaphylaxis Cefuroxime burgdorferi. tablets may be
Secondary bacterial crushed, ifinfection of acute absolutelybronchitis. necessary, for patients who can’t swallow tablets. If large doses are given, therapy is prolonged, or patient is at high risk, monitor patient for signs and symptoms of superinfection. Instruct patient to notify prescriber about rash or evidence of superinfection. Advise patient receiving drug IV to report discomfort at IV insertion site. Tell patient to notify prescriber about loose stools or diarrhea.
CEFTRIAXONE 1.5gm q4 ivtt Uncomplicated Third generation Contraindicated CNS: fever, Before SODIUM gonococcal cephalosporin that in patients headache, dizziness administration, vulvovaginitis inhibits cell-wall hypersensitivity to CV: phlebitis ask patient if he is UTIs; lower synthesis, promoting drug or other GI: allergic to respiratory tract, osmotic instability; cephalosporins. pseudomembranous penicillins or gynecologic, bone and usually bactericidal. Use cautiously in colitis, diarrhea cephalosporins. joint, intra abdominal, patients GU: genital pruritus, Obtain skin, and skin structure hypersensitive to candidiasis specimen for infections; septicemia. penicillin because Hematologic: culture and Meningitis of possibility of eosinophilia, sensitivity tests Neurological cross-sensitivity thrombocytosis, before giving first complications, carditis, with other beta- leucopenia dose. Therapy and arthtritis from lactam antibiotics. Skin: pain, may begin while penicillin. Use cautiously in induration, awaiting results. breast-feeding tenderness at For IM women and in injection site, rash, injection, inject patients with pruritus deep into a large history of colitis or Other: muscle, such as renal insufficiency. hypersensitivity the gluteus reactions, serum maximus or the sickness, lateral aspect o anaphylaxis, chills the thigh. Monitor PT and INR in patients with impaired vitamin K synthesis or low vitamin K stores. Tell patient to report adverse reactions promptly.
Instruct patient to report discomfort at injection site. Tell patient to notify prescriber about loose stools or diarrhoea. PROPRANOLOL 10mg ½ tab po Angina pectoris A non-selective beta Contraindicated CNS: fatigue, Always checkHYDROCHLORIDE To decrease risk of blocker that reduces in patients with lethargy, fever, vivid patient’s apical death after MI cardiac oxygen bronchial asthma, dreams, pulse before Supraventricular, demand by blocking sinus bradycardia hallucinations, giving drug. If ventricular, and atrial catecholamine- and heart block mental depression, extremes in pulse arrhythmias; induced increases in greater than first light-headedness, rates occur, tachyarryhtmias caused heart rate, blood degree, dizziness, insomnia withhold drug and by excessive pressure, and force cardiogenic shock, CV: bradycardia, notify prescriber catecholamine action of myocardial and overt and hypotension, heart immediately. during anesthesia, contraction. decompensated failure, intermittent Give drug huperthyroidism, or Depresses rennin heart failure. claudication, consistently with pheochromocytopenia. secretion and Use cautiously in intensification of AV meals. Food may Hypertension prevents patients with block. increase To prevent frequent, vasodilation of hepatic or renal GI: abdominal absorption of severe, uncontrollable, cerebral arteries. impairment, non- cramping, propranolol. or disabling migraine, or allergic constipation, Drug masks vascular headache. bronchospastic diarrhea, nausea, common signs Essential tremor diseases, or vomiting and symptoms of Hypertrophic hepatic diseases Hematologic: shock and subaortic stenosis and in those taking agranulocytosis hypoglycemia. other Respiratory: Caution patient antihypertensives bronchospasm to continue taking Because drug Skin: rash this drug as blocks some prescribed, even symptoms of when he’s feeling
hypoglycemia, use well. cautiously in Instruct patient patients who have to take drug with diabetes mellitus. food. Use cautiously in Tell patient not patients with to stop drug throtoxicosis suddenly because becaude drug may this can worsen mask some signs chest pain and and symptoms of trigger a heart the disorder. attack. Elderly patients may experience enhanced adverse reactions and may need dosage adjustment.DIAZEPAM 1ml ivtt Anxiety Unknown. A Contraindicated CNS: drowsiness, Use Diastat Acute alcohol benzodiazepine that in patients dysarthia, slurred rectal gel to treat withdrawal probably potentiates hypersensitive to speech, tremor, no more than five Muscle spasm the effects of GABA, drug or soy protein; transient amnesia, episodes per Cardioversion depresses the CNS, in patients fatigue,ataxia, month and no Adjunct treatment and suppresses the experiencing shock, headache, insomnia, more than one for seizure disorders spread of seizure coma, or acute paradoxical anxiety, episode every 5 Status epilepticus, activity. alcohol hallucinations, minor days because severe recurrent intoxication; in changes at EEG tolerance may seizures pregnant women, patterns. develop. Patients on stable especially in first CV: hypotension, CV When using oral regimens of antiseptic trimester; and in collapse, bradycardia concentrate drugs who need children younger EENT: diplopia, solution, dilute diazepam intermittently than 6 months. blurred vision, dose just before to control bouts of Diastat rectal gel nystagmus giving. increase seizure activity. is contraindicated GI: nausea, Monitor in patients with constipation, periodic hepatic,
acute angle-closure diarrhea with rectal renal, and glaucoma. form hematopoietic Use cautiously in GU: incontinence, function studies in patients with liver urine retention patients receiving or renal Hematologic: repeated or impairment, neutropenia prolonged depression, or Hepatic: jaundice therapy. chronic open-angle Respiratory: Use of this drug glaucoma. Use respiratory may lead to abuse cautiously in depression, apnea and addiction. elderly and Skin: rash Don’t withdraw debilitated drug abruptly patients. after long-term use; withdrawal symptoms may occur. Warn woman to avoid use during pregnancy.PARACETAMOL 325mg/tab q4 Fever / mild pain Unknown. Thought Contraindicated Hematologic: Use liquid form prn for fever to produce analgesia in patients hemolytic anemia, for children and by bocking pain hypersensitive neutropenia, patients who have impulses by to drug. leucopenia, difficulty inhibiting synthesis Use cautiously in pancytopenia swallowing. of prostaglandin in patients with Hepatic: jaundice In children the CNS or other long term Metabolic: don’t exceed five substances that alcohol use hypoglycemia doses in 24 hours. sensitize pain because Skin: rash, urticaria receptors to therapeutic stimulation. The doses cause drug may relieve hepatotoxicity in fever through these patients. central action in the hypothalamic heat-
regulating center.MUPIROCIN Treating impetigo, a Mupirocin Ointment Tell your doctor or Burning; pain; Inform pt. that:OINTMENT type of skin infection. is an antibacterial. It pharmacist if you stinging. kills sensitive have any medical If you have bacteria by stopping conditions, Severe allergic any questions the production of especially if any of reactions (rash; about essential proteins the following apply hives; itching; Mupirocin needed by the to you: difficulty breathing; Ointment, bacteria to survive. tightness in the please talk if you are chest; swelling of the with your pregnant, mouth, face, lips, or doctor, planning to tongue); severe pharmacist, or become irritation; severe other health pregnant, or itching. care provider. are breast- Mupirocin feeding Ointment is to if you are be used only taking any by the patient prescription or for whom it is nonprescriptio prescribed. Do n medicine, not share it herbal with other preparation, or people. dietary If your supplement symptoms do if you have not improve allergies to or if they medicines, become foods, or other worse, check substances with your if you are doctor. treating a burn or open wound
if you have kidney problemsCLOXACILLIN Cloxacillin is used to Disrupt the synthesis If you have ever an allergic Take cloxacillin treat many different of the peptidoglycan had an allergic reaction exactly as directed types of infections layer of bacterial cell reaction to another (shortness of by your doctor. If caused by walls. The penicillin or to a breath; closing of you do not staphylococcus bacteria peptidoglycan layer cephalosporin, do your throat; understand these ("staph" infections). is important for cell not take cloxacillin hives; swelling of instructions, ask wall structural unless your doctor your lips, face, or your pharmacist, integrity. is aware of your tongue; rash; or nurse, or doctor allergy and fainting); to explain them to monitors your seizures; you. therapy. severe watery diarrhea and Take each dose Before taking this abdominal with a full glass of medication, tell cramps; or water. Take your doctor if you unusual bleeding cloxacillin on an have kidney or bruising. empty stomach 1 disease, stomach or hour before or 2 intestinal disease, hours after meals. or infectious mononucleosis. Do not drink juice You may not be or carbonated able to take beverages (soda) cloxacillin because with your dose of of an increased risk cloxacillin. These of side effects. beverages will decrease the If you are a effectiveness of diabetic, some the drug. glucose urine tests may give false Cloxacillin should
positive results be taken at evenlywhile you are spaced intervalstaking cloxacillin. throughout the day and night toCloxacillin is in the keep the level inFDA pregnancy your blood highcategory B. This enough to treatmeans that it is the infection.unlikely to harm anunborn baby. Do Do not crush,not, however, take chew, or open thecloxacillin without capsules. Swallowfirst talking to your them whole.doctor if you are Shake thepregnant. It is not suspension wellknown whether before measuringcloxacillin passes a dose. To ensureinto breast milk. Do that you get anot take this correct dose,medication without measure thefirst talking to your liquid form ofdoctor if you are cloxacillin with abreast-feeding a dose-measuringbaby. spoon or cup, not a regular tablespoon. If you do not have a dose-measuring device, ask your pharmacist where you can get one. Take all of the cloxacillin that has been prescribed
for you even ifyou begin to feelbetter. Yoursymptoms maystart to improvebefore theinfection iscompletelytreated. Store thecapsules at roomtemperature andstore thesuspension in therefrigerator forlonger use. Thesuspension isgood for 14 days ifit is stored in therefrigerator.Throw away anyunused liquidafter this amountof time.
ANATOMY AND PHYSIOLOGYHUMAN HEART The human heart is located in the thoracic cavity, behind and slightly to the left of the sternum. The heart is tilted so that its pointed end, the apex, points downward toward the left hip, while the broad end, the base, faces upward toward the right shoulder. It is bordered laterally by the lungs, anteriorly by the sternum, posteriorly by the vertebral column, and inferiorly by the diaphragm, making it a well-protected organ. The heart weighs 7-15 ounces (200-425 grams) and is approximately the size of the individuals fist. It is approximately 12cm long, 9cm wide at the broadest point, and 6cm thick. The apex is formed by the tip of the left ventricle and is located at the level of the 5th intercostals space. The base is formed by the atria at the level of the second rib. A protective sac called the pericardiumsurrounds the heart. It consists of the followinglayers: Fibrous anchors the heart in the mediastinum, surrounds roots of the major blood vessels, prevents over- distention, tough protective layer Parietal lies directly beneath the fibrous Visceral (Epicardium) lies beneath parietal, attached to the heart itself Pericardial fluid (up to 50ml) ultra filtrate of plasma provides a slippery surface for the movements ofthe heart which prevents friction, located in pericardial cavity. The wall of the heart consists of three layers: The epicardium is the visceral layer of the serous pericardium. The myocardium is the muscular part of the heart that consists of contracting cardiac muscle and non-contracting Purkinje fibers that conduct nerve impulses. The endocardium is the thin, smooth, endothelial, inner lining of the heart, which is continuous with the inner lining of the blood vessels.
CHAMBERS OF THE HEART The heart consists of 2 muscular pumps known asthe left and right ventricles. The ventricles have 2reservoirs called atria (left and right). Each ventricle acts toserve different circulations. The right ventricle shiftsdeoxygenated blood into the pulmonary circulation. Bloodenters the network of capillaries in the lungs and through aprocess of diffusion carbon dioxide is lost and oxygen isacquired; it then returns to the left atrium. The leftventricle is the pump responsible for delivering blood intothe systemic circulation where it carries nutrients andoxygen to the tissues. An exchange of nutrients and oxygenfor carbon dioxide and waste takes place; the waste richblood now returns to the right atriumHEART VALVES Atrioventricular (AV) valves lie between atria and ventricles • Tricuspid - on the right • Mitral (bicuspid) - on the left • Papillary muscles - attach to lower ventricular walls and to chordae tendineae which in turn attach to the AV valves. These keep the cusps of the AV valves from being inverted into the atria when the ventricles contract. Semilunar valves between ventricles and great vesselsexiting the heart • Pulmonary - between RV and pulmonary trunk • Aortic- between LV and aorta As blood travels through the heart, it enters a total of four chambers and passes through fourvalves. The two upper chambers, the right and left atria, are separated longitudinally by the interatrialseptum. The two lower chambers, the right and left ventricles, are the pumping machines of the heartand are separated longitudinally by the interventricular septum. A valve follows each chamber andprevents the blood from flowing backward into the chamber from which the blood originated.Two additional passageways are present in the fetal heart: The foramen ovale is an opening across the interatrial septum. It allows blood to bypass the right ventricle and the pulmonary circuit, while the nonfunctional fetal lungs are still developing.
The opening, which closes at birth, leaves a shallow depression called the fossa ovalis in the adult heart. The ductus arteriosus is a connection between the pulmonary trunk and the aorta. Blood that enters the right ventricle is pumped out through the pulmonary trunk. Although some blood enters the pulmonary arteries (to provide oxygen and nutrients to the fetal lungs), most of the blood moves directly into the aorta through the ductus arteriosus. THE GREAT VESSELS OF THE HEART Superior vena cava: brings deoxygenated blood into the right atrium from the head and upper body veins Inferior vena cava: brings deoxygenated blood from legs and lower torso into right atrium Pulmonary arteries (R and L): branch from pulmonary trunk, carry deoxygenated blood from the right ventricle into the lungs Pulmonary veins (4): carry oxygenated blood from lungs into the left atrium Ascending Aorta: receives oxygenated blood from the left ventricle and pumps it throughout the body via arteriesBLOOD VESSELS The central opening of a blood vessel, the lumen, issurrounded by a wall consisting of three layers: The tunica intima is the inner layer facing the blood. It is composed of an innermost layer of endothelium (simple squamous epithelium) surrounded by variable amounts of connective tissues. In arteries this layer is composed of an elastic membrane lining and smooth endothelium that is covered by elastic tissues. The tunica media, the middle layer, is composed of smooth muscle with variable amounts of elastic fibers. This layer is thicker in arteries than in vein. The tunica adventitia, the outer layer, is composed of connective tissue as well as collagen and elastic fibres. These fibres allow the arteries and veins to stretch to prevent overexpansion due to the pressure that is exerted on the walls by blood flow.
Blood vessels have three kinds that form a closed system of passageways: Arteries carry blood away from the heart. The three kinds of arteries are categorized by size and function: o Elastic arteries (conducting arteries) are the largest arteries and include the aorta and other nearby branches. The tunica media of elastic arteries contains a large amount of elastic connective tissue, which enables the artery to expand as blood enters the lumen from the contracting heart. During relaxation of the heart, the elastic wall of the artery recoils to its original position, forcing blood forward and smoothing the jerky discharge of blood from the heart. o Muscular arteries (conducting arteries) branch from elastic arteries and distribute blood the various body regions. Abundant smooth muscle in the thick tunica media allows these arteries to regulate blood flow by vasoconstriction (narrowing of the lumen) or vasodilation (widening of the lumen). Most named arteries of the body are muscular arteries. o Arterioles are small, nearly microscopic, blood vessels that branch from muscular arteries. Most arterioles have all three tunics present in their walls, with considerable smooth muscle in the tunica media. The smallest arterioles consist of endothelium surrounded by a single layer of smooth muscle. Arterioles regulate the flow of blood into capillaries by vasoconstriction and vasodilation. Capillaries are microscopic blood vessels with extremely thin walls. Only the tunica intima is present in these walls, and some walls consist exclusively of a single layer of endothelium. Capillaries penetrate most body tissues with dense interweaving networks called capillary beds. The thing walls of capillaries allow the diffusion of oxygen and nutrients out of the capillaries, while allowing carbon dioxide and wastes into the capillaries. o Metarterioles (precapillaries) are the blood vessels between arterioles and venules. Although metarterioles pass through capillary beds with capillaries, they are not true capillaries because metarterioles, like arterioles, have smooth muscle present in the tunica media. The smooth muscle of a metarteriole allows it to acts as a shunt to regulate blood flow into the true capillaries that branch from it. The thoroughfare channel, the tail end of the metarteriole that connects to the venule, lacks smooth muscle. o True capillaries form the bulk of the capillary bed. They branch away from a metarteriole at its arteriole end and return to merge with the metarteriole at its venule end (thoroughfare channel). o Some true capillaries connect directly from an arteriole to a metarteriole or venule. Although the walls of true capillaries lack muscle fibers, they possess a ring of smooth muscle called a precapillary sphincter where they emerge from the metarteriole. The precapillary sphincter regulates blood flow through the capillary. There are three types of true capillaries:
Continuous capillaries have continuous, unbroken walls consisting of cells that are connected by tight junctions. Most capillaries are of this type. Fenestrated capillaries have continuous walls between endothelial cells, but the cells have numerous pores (fenestrations) that increase their permeability. These capillaries are found in the kidneys, lining the small intestine, and in other areas where a high transfer rate of substances into or out of the capillary is required. Sinusoidal capillaries (sinusoids) have large gaps between endothelial cells that permit the passage of blood cells. These capillaries are found in the bone marrow, spleen, and liver. Veins carry blood toward the heart. The three kinds of veins are listed here in the order that they merge to form increasingly larger blood vessels: o Postcapillary venules, the smallest veins, form when capillaries merge as they exit a capillary bed. Much like capillaries, they are very porous, but with scattered smooth muscle fibers in the tunica media. o Venules form when postcapillary venules join. Although the walls of larger venules contain all three layers, they are still porous enough to allow white blood cells to pass. o Veins have walls with all three layers, but the tunica intima and tunica media are much thinner than in similarly sized arteries. Few elastic or muscle fibers are present. The wall consists of primarily of a well-developed tunica adventitia. Many veins, especially those in the limbs, have valves, formed from folds of the tunica intima, which prevent the backflow of blood. Many regions of the body receive blood supplies from two or more arteries. The points wherethese arteries merge are called arterial anastomoses. Arterial anastomoses allow tissues to receiveblood even after one of the arteries supplying blood has been blocked.BLOOD FLOW THROUGH THE HEART The heart has four chambers that pumpblood. The chambers are called the right atrium,right ventricle, left atrium, and left ventricle. Theright and left sides of the heart are separated bymuscular wall called the septum. This preventsblood without oxygen from mixing withoxygenated blood. The heart also has valves thatseparate the chambers and connect to major bloodvessels. Blood flows from the body into the rightatrium. The blood on the right side of the hearthad been used by the body and is deoxygenated oroxygen-poor.