Lesson 1.2
DIAGNOSTIC PROCEDURES

1-8. INTRODUCTION

Cardiovascular diagnostic tests and examinations are conducted by order of the physician to help him determine the nature of the specific disease condition. Many of these tests or examinations may be repeated at intervals to determine the patient's progress or response to prescribed treatment. While some are performed on the nursing unit, many others are conducted only in special laboratories and hospital clinics.

The nursing paraprofessional's role in assisting with diagnostic tests and collection of specimens will vary, depending upon the test, the specimen, the condition of the patient, and the local situation and policy. Although they may seldom perform any part of the test themselves, they should be acquainted with those commonly performed in order to give intelligent patient care and appropriate assistance to the doctor, nurse, or technician. In general, they should know:

(1) How and why the procedure is done and what, if any, reaction is expected from it.

(2) What explanation and physical care the patient should have before, during, and after the procedure. The informed, prepared patient is more apt to cooperate and to tolerate any inconvenience or discomfort incidental to the test.

(3) What equipment, clean or sterile, must be provided when assisting with the procedure and how to care for used equipment following the procedure.

(4) The role of the assistant in relation to that of the doctor, nurse, or technician performing the test.

1-9. GENERAL PREPARATORY MEASURES FOR PROCEDURES PERFORMED OFF THE NURSING UNIT

Procedures vary from one hospital to another concerning nursing unit preparation of patients who are to be sent or escorted to clinics, laboratories, radiology, or operating rooms. These various departments set their own standing operating procedure in accordance with local directives and issue instructions to the nursing units. These instructions and the doctor's orders for the particular patient must be carried out  carefully to ensure the best results for the patient. A few general rules to remember are:

a. Prepare the Patient Mentally. Tell the patient briefly what to expect and explain his role in the preparation.  Mental preparation of the patient gives him emotional security and gains his confidence and cooperation.

CAUTION: Always verify with the nurse or doctor what information you may give to the patient.

b. Prepare the Patient Physically. Have the patient clean, properly dressed, and protected from exposure or drafts. Make sure that any specific preparation ordered has been accomplished, such as medication, rest for a required period, or restriction on food or liquids.

c. Have the Right Patient in the Right Place at the Right Time. If he is an ambulatory patient, give him specific directions on how to reach the clinic or laboratory. Transport an otherwise ambulatory patient who has received a sedative or other pretreatment medication in a wheelchair or on a stretcher. The responsibility of nursing unit personnel accompanying the patient ends only after the patient is placed in the care of the personnel who are to perform the procedure.

1-10.  GENERAL NURSING CARE DURING DIAGNOSTIC PROCEDURES PERFORMED ON THE NURSING UNIT

In addition to the general rules mentioned in the previous paragraph, you should:

a. Assist the physician as required. This may involve obtaining equipment, opening sterile trays, preparing a sterile field, pouring solutions, preparing the patient's skin, positioning the patient, draping the patient, and assisting the physician in the performance of the procedure.

b. Reassure the patient and make him as comfortable as possible.

NOTE: For some patients and some procedures, two assistants will be needed one to support and observe the patient and one to assist the doctor.

c. If a specimen is taken, attach to the specimen container a prepared label identifying the patient by name and register number, ward, date, and test. Forward the specimen to the laboratory immediately with the proper laboratory request slip.

1-11.  GENERAL NURSING CARE FOLLOWING DIAGNOSTIC PROCEDURES

a. Return the patient to his bed by the means ordered.

b. Check the orders of the physician who performed the procedure. Observe and report any unusual reactions of the patient.  If there are no orders pertaining to taking vital signs, accomplish this nursing measure according to standard nursing unit procedures.

c. Use appropriate measure to relieve discomfort or pain.

d. If the patient has been sedated or anesthetized, ensure bed rest until he has completely reacted. Tell him to stay in bed and to signal for any needs. Use side rails according to standard procedures. Ensure the call light is with in reach of the patient.

e. If the procedure involves the patient's diet, notify food service to serve, modify, or cancel his meal as appropriate.

f. Explain to the patient that he will be notified when he may resume his normal regime. When this time arrives, inform him promptly.

g. Record the following information in the nursing notes.

(1) Date and time.

(2) Type of procedure.

(3) Where and by whom performed.

(4) Disposition of specimen, if taken.

(5) Significant observations on patient's reaction such as pain, discomfort, and apprehension.

(6) Patient's vital signs before and after the procedure (when these are required).

1-12.  FLUOROSCOPY

Fluoroscopy shows the heart in action and is used more often than other x-ray methods in cardiologic examinations. Fluoroscopy is used to look for abnormal configuration, tumors, and calcifications in the heart, aorta, and pulmonary vessels, to find congestion of the lungs, and to detect pleural or pericardial effusions. During examination of the heart under fluoroscopy, barium is given by mouth so the outline of the esophagus can be seen. An enlarged left atrium pushes the esophagus aside as it becomes larger. There is no preparation of the patient for this examination.

1-13.  INTRAVENOUS ANGIOCARDIOGRAPHY

This is a procedure in which an opaque medium is injected into a vein followed by a rapid series of x-ray pictures taken of the course of the medium through the heart, to the lungs, back to the heart, and out through the aorta. The dosage of contrast media is calculated according to the kilograms of body weight. The solution is injected through a large bore (12 gauge) needle held in position in the vein, usually by a "cut down." Speed of injection is imperative, since the solution must pass through the heart in a large bolus to make possible a good examination. The solution is injected after the patient has been instructed to inhale deeply. The inspiration is held for the entire series of x-rays.

a. This diagnostic method is recognized for precision in detecting congenital cardiac defects. Individual chambers of the heart are visualized, pathways for the blood stream are demonstrated, and chamber enlargement can be seen.

b. The opaque medium may cause a flushing sensation as it flows through the body. If necessary, the studies may be conducted under mild anesthesia. After one complete circulation, the opaque media is so diluted that it is no longer visible by x-ray.

c. No special preparation of the patient is necessary unless anesthesia is to be given. In that event, food may be withheld prior to the studies. A record of the patient's weight should be sent to the x-ray department with him.

1-14.  AORTOGRAM

The aorta and its branches are studied by the injection of a contrast medium through a plastic catheter or with a needle directly into the aorta. Terms used in connection with the aortogram are retrograde aortogram (retrograde meaning against the direction of blood flow) and translumbar aortogram (meaning the injection is made below the twelfth rib and to the left of the spine). No preparation of the patient is necessary.

1-15.  CARDIAC CATHETERIZATION

This is a procedure in which a radiopaque catheter is manipulated through the heart under fluoroscopic observation. The exterior end of the catheter is connected by a three-way stopcock to a saline filled regulated drip system that also contains a pressure gauge (strain gauge) and a camera. During the procedure the blood pressures within the heart are automatically transmitted to the strain gauge that, in turn, transmits the pressure to the camera recording the findings on photographic film.

Samples of blood are also withdrawn from the heart chambers and great vessels. The samples are analyzed for oxygen content.

a. The pressures within the heart indicate any existing strain placed on individual heart chambers. The oxygen content indicates whether the blood is circulating directly through the heart or whether the blood is being shunted because of an anatomical defect.

b. During the entire procedure an electrocardiograph and an electro-tachometer is recording readings on photographic paper. The electro-cardio-tachometer is connected by leads that operate, as do those of the electrocardiograph and instantaneously records the heart rate. It also contains a small light that flashes on with each heartbeat, thus enabling the doctor to observe in the dark the condition of the patient.

c. There are several routes used for the catheter approach to the heart. Not long ago only the right side of the heart was studied by catheterization. The cardiac catheter was inserted by means of a "cut-down" into the antecubital vein of either arm, then manipulated through the innominate vein, superior vena cava, right atrium, tricuspid valve, right ventricle, semilunar valve, and pulmonary artery. The cardiac catheter may also be placed in the right or left femoral vein, then manipulated through the inferior vena cava it may then follow the same path as the catheter entered through the antecubital vein.

d. Several studies also include the left side of the heart. The approach is made directly to the left atrium by means of an 18-gauge, 6-inch needle with a stylet through the patient's back directly into the heart. After the tip of the needle is placed in the left atrium, the stylet is removed and the catheter is manipulated into the left atrium, left ventricle, and the ascending aorta.

e. Studies now also include the examination of both sides of the heart simultaneously through the transthoracic introduction of two needles, one in each atrium.

f. The patient is taken to the fluoroscopy or cardiology department for the study. The entire procedure may last from 1 to 3 hours. The procedure is a painless one. The patient is prepared as follows:

(1) Solid foods are withheld. Liquids are permitted up to 3 hours prior to the procedure.

(2) Diphenhydramine and Valium may be given 30 minutes prior to the procedure.

(3) A systemic antibiotic may be administered prophylacticly to prevent infection.

(4) After the procedure the patient is returned to his nursing unit, remaining flat in bed for 24 hours or more. The vital signs and insertion site are checked every 10 minutes during the first hour, then every 30 minutes for 3 hours. The patient may be nauseated following the procedure.

1-16.  ELECTROCARDIOGRAM

a. The electrocardiogram (ECG or EKG) is a graphic recording of the electrical impulses produced in association with the heartbeat. Impulse formation and conduction produce weak electrical currents that spread throughout the entire body. By connecting certain points on the body to a recording instrument, these currents can be recorded as a graphic representation of the heartbeat, measured against time. Time is expressed on the special ECG graph paper by vertical and horizontal lines.

b. Normally, each heartbeat is represented as five major waves: P, Q, R, S, and T. The Q,R, and S waves all represent the same portion of the heart and are referred to as a unit: the QRS complex.

(1) The P wave represents atrial depolarization. The QRS complex represents ventricular depolarization.

(2) The QRS complex represents the impulse traveling through the ventricles, at which time there is no heart contraction.

(3) The T wave is produced by electrical recovery of the ventricles, at which time there is no heart contraction it represents ventricular repolarization.

c. The standard ECG machine utilizes 12 "leads." These leads represent paths of electrical activity and are designated as leads I, II, III, aVR, aVL, aVF, V1, V2, V3, V4, V5, and V6. It is neither practical nor necessary to go into an explanation of leads in  this text. To do so would require extensive explanation of electrophysiological principles. It will suffice to say that each lead senses and records the electrical  impulses from different positions related to the heart's surface. Since each lead takes a different view of heart activity, it generates its own characteristic tracing. Wave abnormalities that appear in the different leads indicate damage or defects in particular portions of the heart muscle.

d. The ECG provides quite a bit of valuable information for the small amount of effort involved in obtaining an ECG recording. It is a procedure that is completely noninvasive and without risk to the patient. It is easily performed by anyone with the proper training. The ECG provides information about the heart rate, rhythm, the condition of the myocardium, the presence of ischemia or necrosis, conduction abnormalities, the presence of certain drugs, and the effects of disturbed electrolytes.

e. Because it does provide so much valuable information, it is important that the procedure be performed correctly. Correct procedure will vary depending upon the type of equipment used in your facility. Be sure to read the local standard operating procedures (SOP) and the manufacturer's instructions before attempting to use the equipment. Another important factor in correct performance is proper placement of the electrodes. Electrodes should be secured over a fleshy area, not over a bone, as bone interferes with the electrical impulse readings. In order to obtain accurate readings the patient may need to be shaved using a prep razor if the area where the electrodes are to be placed. Location of the electrodes is standard for all designs of ECG equipment.

(1) Leg electrodes are best placed on the medial or lateral aspect of the calf to avoid contact with bone.

(2) Arm electrodes are best placed on the inner aspect of the arm or forearm, several inches above or below the antecubital space.

(3) Chest electrodes are placed as follows. Remember to place the electrodes over the intercostal spaces, not over the ribs.

V1: 4th intercostal space at the right sternal border.
V2: 4th intercostal space at the left sternal border.
V3: Halfway between V2 and V4.
V4: 5th intercostal space at the midclavicular line.
V5: 5th intercostal space at the anterior axillary line.
V6: 5th intercostal space at the midaxillary line.

1-17.  STRESS TEST

Stress testing or exercise testing is done to assess cardiac function. Stress testing is accomplished by having the patient climb stairs, pedal a stationary bicycle, or walk a treadmill. The exercise is gradually increased (climb or walk faster, pedal harder) while the patient is monitored. Electrocardiogram electrodes attached to the patient record tracings before, during, and after exercise. Additionally, blood pressure, physical appearance, and chest pain levels are monitored closely.

1-18.  BLOOD STUDIES

a. Electrolytes. Serum electrolyte studies are frequently performed on cardiac patients. Of particular significance are calcium, sodium, and potassium.

(1) Calcium has a role in cell permeability, formation of bones and teeth, blood cell coagulation, nerve impulse conduction, and normal muscle contraction. Elevated calcium levels (hypocalcaemia) may cause HTN and cardiac arrest. Decreased calcium levels (hypocalcaemia) may cause tetany, convulsions, hypotension, and cardiac arrhythmias.

(2) Sodium functions in maintaining the concentration of extra cellular fluid, acid-base balance, water balance, and nerve conduction. Elevated sodium levels (hypernatremia) may cause weight gain, pitting edema, HTN, and tachycardia. Decreased sodium levels (hyponatremia) may cause hypotension and tachycardia.  If depletion is severe, vaso-motor collapse may occur.

(3) Potassium is the dominant cellular electrolyte. It facilitates contraction of skeletal and smooth muscle to include myocardial contraction. Potassium is also concerned in acid-base balance, nerve impulse conduction, and cell membrane function. Both decreased potassium levels (hypokalemia) and increased potassium levels (hyperkalemia) diminish the excitability and conduction rate of the cardiac  muscle. This may lead to bradycardia, tachycardia, cardiac arrhythmias, and cardiac arrest.

b. Cultures. Blood cultures are performed to detect the presence of bacteria in the blood. This test is useful in the diagnosis of bacterial endocarditis.

c. Enzymes. Enzyme studies are done to detect damage to the myocardium. The enzymes creatine phosphokinase (CPK) and lactic dehydrogenase (LDH) are found in increased levels after myocardial tissue damage.  However, these enzymes are also present in other tissue, and blood levels may be elevated as a result of damage to skeletal muscles, the liver, the kidneys, and other organs. This results in a false positive.

d. Isoenzymes. Isoenzymes are forms of enzymes that can be differentiated from one another.

(1) One isoenzyme of the enzyme CPK is present in significant amounts only in myocardial tissue. This isoenzyme is identified as CPK-MB.

(2) Lactic dehydrogenase has five isoenzymes, and cardiac muscle is associated with large amounts of the isoenzymes LDH1.

(3) The determination of the isoenzymes (CPK-MB and LDH is more specific in evaluation myocardial damage than simple enzyme determinations.

1-19.  PULSE

a. Each time the heart beats, the left ventricle contracts and sends blood through the arteries. The pulse is the rhythmic expansion of the arteries that results from each heartbeat. The pulse may be felt most strongly over the following areas:

(1) Radial artery in the wrist at the base of the thumb.

(2) Temporal artery in front of the ear.

(3) Carotid artery in the neck.

(4) Femoral artery in the groin.

(5) Over the apex (tip) of the heart (apical pulse).

b. Two other locations for palpation of the pulse are the popliteal artery at the back of the knee and the pedal pulses of the foot. Pedal pulses are located on both the lateral and medial aspects of the ankle and on the top of the foot. These pulses are often difficult to locate.

c. The physician may request that both a radial and apical pulse be taken simultaneously to see if there is a difference in rates. A significant difference is indicative of vascular disease. This difference between the apical and radial pulse is known as the pulse deficit.

d. When the pulse is being counted, the rate, rhythm, and volume (force) should be noted.

(1) Rate may be noted as normal, fast (tachycardia), or slow (bradycardia). An average pulse rate for a resting adult is 70-80 bpm (beats per minute). Rates faster than 100 bpm are considered to be tachycardia. Rates slower than 60 bpm are considered to be bradycardia.

NOTE:  A well-trained athlete may have a resting pulse of less than 50 bpm.

(2) Rhythm is the regularity of the pulse beats. Rhythm is described as irregular when you can feel the pulsations occur at different rates. A normal rhythm has the same time interval between the beats.

(3) Volume is the force or strength of the pulse. Terms used to describe the volume (force) of the pulse are weak, thready, or feeble for a pulse that lacks strength, and strong, full, or bounding for a pulse that feels forceful. Additionally, the force may be regular or irregular.

e. There are many factors that affect the pulse rate. Some are listed below.

(1) Sex. Women have a slightly faster pulse rate than men.

(2) Age. The pulse rate gradually decreases from birth to adulthood then increases with advancing old age.

(3) Body temperature. The pulse rate generally increases 7-10 beats for each degree of temperature elevation.

(4) Digestion. The increased metabolic rate during digestion will increase the pulse rate slightly.

(5) Pain. Pain increases pulse rate.

(6) Emotion. Fear, anger, anxiety, and excitement increase the pulse rate.

(7) Exercise. The heart must beat faster during exercise to meet the increased demand for oxygen.

(8) Blood pressure.  In general, heart rate and blood pressure have an inverse relationship. When the blood pressure is low, there is an increase in pulse rate as the heart attempts to increase the output of blood from the heart (cardiac output).

1-20.  BLOOD PRESSURE

a. Blood pressure is defined as the pressure exerted by the blood on the walls of the blood vessels. When speaking of blood pressure, it is the arterial blood pressure that we are concerned with. When taking a patient's blood pressure with a sphygmomanometer and stethoscope, it is the arterial blood pressure that is being measured.

b. Blood pressure is registered by two numbers that represent the pressures exerted during contraction and relaxation of the heart.

(1) Systolic pressure is the maximum pressure occurring during systole, or contraction, of the ventricles. It is the higher of the two numbers. Normal systolic pressure for the average resting adult is between 100-150 mmHg.

(2) Diastolic pressure is the pressure occurring during diastole, the period of relaxation and filling of the ventricles. This is the lowest pressure. Normal diastolic pressure for the average resting adult is between 60-90 mmHg.

c. Blood pressure is best measured over a large artery. The most commonly used is the brachial artery. The cuff is wrapped around the upper arm and auscultation is done over the brachial artery in the antecubital space.

(1) With extremely obese patients, the application of the cuff around the forearm and auscultation over the radial artery may give a truer measurement of blood pressure.

(2) Blood pressure may also be taken in the leg by wrapping the cuff around the thigh and auscultating the popliteal artery behind the knee.

(3) An accurate blood pressure reading depends upon the width of the cuff in relation to the diameter of the limb used. If the cuff is too large for the limb, as in a child, the reading obtained could be significantly lower than the true pressure. If the cuff is too small for the limb, as in an obese person, the reading obtained may be higher than the true pressure.

d. Blood pressure depends upon the force of the heartbeat, the volume of blood in the circulatory system, and the resistance within the blood vessels. Other factors that affect blood pressure are:

(1) Pain. Moderate to severe pain will increase blood pressure.

(2) Emotions. Fear, anger, anxiety, or excitement will increase blood pressure.

(3) Disease. Disease conditions may cause abnormal increase or decrease of blood pressure.

e. In patients with hypertension or other cardiovascular disease, it is best to measure blood pressure in both the right and left arms. There should be no more than 5 mmHg difference between the two readings. A greater difference is indicative of vascular disease.

f. The physician may order blood pressure checks to be done with the patient lying down, sitting, and standing. The corresponding rise or fall in pressure with the change of position may give the physician valuable information about the nature of the cardiovascular disease.

g. Pulse pressure is the difference between the systolic and diastolic pressures. Normal range for pulse pressure should be 30-50 mmHg, with 40 mmHg the average.

(1) A decreased pulse pressure (less than 30 mmHg) is related to factors that cause an increase in the diastolic blood pressure, a decrease in systolic blood pressure, or a combination of both. Causes of decreased pulse pressure included peripheral vasoconstriction, aortic valve stenosis, mitral valve insufficiency, or decreased stroke volume due to heart failure or hypovolemia.

(2) An increased pulse pressure (greater than 50 mmHg) is related to  factors that cause a decrease in the diastolic blood pressure, an increase in systolic blood pressure, or both. Causes of increased pulse pressure include hypertension, circulatory overload, arrhythmias, increased stroke volume caused by anxiety or exercise, or decreased distensibility of the arteries as seen in arteriosclerosis and aging.