The Physical Examination and Its Basis in Physiology



The Physical Examination and Its Basis in Physiology



Chapter Objectives


After reading this chapter, you will be able to:


• Describe the major components of a patient’s vital signs, including:


• Body temperature


• Pulse


• Respiration


• Blood pressure


• Oxygen saturation


• Describe the systematic examination of the chest and lungs, including:


• Lung and chest topography


• Inspection


• Palpation


• Percussion


• Auscultation


• Discuss in more depth the common clinical manifestations observed during inspection, including normal ventilatory pattern and the common pathophysiologic mechanisms that affect the ventilatory pattern.


• Describe the function of the following accessory muscles of inspiration:


• Scalene


• Sternocleidomastoid


• Pectoralis major


• Trapezius


• Describe the function of the following accessory muscles of expiration:


• Rectus abdominis


• External oblique


• Internal oblique


• Transversus abdominis


• Discuss the effects of pursed-lip breathing.


• Describe the pathophysiologic basis for substernal and intercostal retractions.


• Explain nasal flaring.


• Discuss splinting caused by chest pain or decreased chest expansion including pleuritic chest pain and nonpleuritic chest pain.


• List abnormal chest shape and configuration.


• List abnormal extremity findings, and include:


• Altered skin color (e.g., cyanotic, pale, with prominent venous distention)


• Presence or absence of digital clubbing


• Presence or absence of peripheral edema


• Presence or absence of distended neck veins


• Describe how the following correlates to normal and abnormal sputum production, including:


• Normal histology and mucous production of the tracheobronchial tree


• Abnormal sputum production


• Cough


• Define key terms and complete self-assessment questions at the end of the chapter and on Evolve.



Key Terms
































































































































Vital Signs


The four major vital signs—body temperature (T), pulse (P), respiratory rate (R), and blood pressure (BP)—are excellent bedside clinical indicators of the patient’s physiologic and psychologic health. In many patient care settings, the oxygen saturation as measured by pulse oximetry (Spo2) is considered to be the fifth vital sign. Table 2-1 shows the normal values that have been established for various age groups.



During the initial measurement of a patient’s vital signs, the values are compared with these normal values. After several vital signs have been documented, these data are then used as a baseline for subsequent measurements. Isolated vital sign measurements are not as valuable as a series of measurements. By evaluating a series of values, the practitioner can identify important vital sign trends for the patient. The identification of vital sign trends that deviate from the patient’s normal measurements is often more significant than an isolated measurement.


Although the skills involved in obtaining the vital signs are easy to learn, interpretation and clinical application require knowledge, problem-solving skills, critical thinking, and experience. Even though vital sign measurements are part of routine bedside care, they provide important information and should always be considered as an important part of the assessment process. The frequency with which vital signs should be assessed depends on the individual needs of each patient.



Body Temperature


Body temperature is routinely measured to assess for signs of inflammation or infection. Even though the body’s skin temperature varies widely in response to environmental conditions and physical activity, the temperature inside the body, the core temperature, remains relatively constant—about 37° C (98.6° F), with a daily variation of ±0.5° C (1° to 2° F). Under normal circumstances the body is able to maintain this constant temperature through various physiologic compensatory mechanisms, such as the autonomic nervous system and special receptors located in the skin, abdomen, and spinal cord.


In response to temperature changes the receptors sense and send information through the nervous system to the hypothalamus. The hypothalamus, in turn, processes the information and activates the appropriate response. For example, an increase in body temperature causes the blood vessels near the skin surface to dilate—a process called vasodilation. Vasodilation, in turn, allows more warmed blood to flow near the skin surface, thereby enhancing heat loss. In contrast, a decrease in body temperature causes vasoconstriction, which works to keep warmed blood closer to the center of the body—thus working to maintain the core temperature.


At normal body temperature, the metabolic functions of all body cells are optimal. When the body temperature increases or decreases significantly from the normal range, the metabolic rate and therefore the demands on the cardiopulmonary system also change. For example, during a fever the metabolic rate increases. This action leads to an increase in oxygen consumption and to an increase in carbon dioxide production at the cellular level. According to estimates, for every 1° C increase in body temperature, the patient’s oxygen consumption increases about 10%. As the metabolic rate increases, the cardiopulmonary system must work harder to meet the additional cellular demands. Hypothermia reduces the metabolic rate and cardiopulmonary demand.


As shown in Figure 2-1, the normal body temperature is positioned within a relatively narrow range. A patient who has a temperature within the normal range is said to be afebrile. A body temperature above the normal range is called pyrexia or hyperthermia. When the body temperature rises above the normal range, the patient is said to have a fever or to be febrile. An exceptionally high temperature, such as 41° C (105.8° F), is called hyperpyrexia.


image
FIGURE 2-1 Range of normal body temperature and alterations in body temperature on the Celsius and Fahrenheit scales. See conversion formulas for Fahrenheit and Celsius scales on left side of figure.

The four common types of fevers are intermittent fever, remittent fever, relapsing fever, and constant fever. An intermittent fever is said to exist when the patient’s body temperature alternates at regular intervals between periods of fever and periods of normal or below-normal temperatures. In other words, the patient’s temperature undergoes peaks and valleys, with the valleys representing normal or below-normal temperatures. During a remittent fever, the patient has marked peaks and valleys (more than 2° C or 3.6° F) over a 24-hour period, all of which are above normal—that is, the body temperature does not return to normal between the spikes. A relapsing fever is said to exist when short febrile periods of a few days are interspersed with 1 or 2 days of normal temperature. A continuous fever is present when the patient’s body temperature remains above normal with minimal or no fluctuation.


Hypothermia is a core temperature below normal range. Hypothermia may occur as a result of (1) excessive heat loss, (2) inadequate heat production to counteract heat loss, and (3) impaired hypothalamic thermoregulation. Box 2-1 lists the clinical signs of hypothermia.



Box 2-1   Clinical Signs of Hypothermia




Hypothermia may be caused accidentally or may be induced. Accidental hypothermia is commonly seen in the patient who (1) has had an excessive exposure to a cold environment; (2) has been immersed in a cold liquid environment for a prolonged time; or (3) has inadequate clothing, shelter, or heat. A reduced metabolic rate may compound hypothermia in older patients. In addition, older patients often take sedatives, which further depress the metabolic rate. Box 2-2 lists common therapeutic interventions for patients with hypothermia.



Box 2-2   Common Therapeutic Interventions for Hypothermia




Induced hypothermia refers to the intentional lowering of a patient’s body temperature to reduce the oxygen demand of the tissue cells. Induced hypothermia may involve only a portion of the body or the whole body. Induced hypothermia is often indicated before certain surgeries, such as heart or brain surgery.



Factors Affecting Body Temperature


Table 2-2 lists several factors that affect body temperature. Knowing these factors can help the practitioner to better assess the significance of expected or normal variations in a patient’s body temperature.



Table 2-2


Factors Affecting Body Temperature





















Age Temperature varies with age. For example, the temperature of the newborn infant is unstable because of immature thermoregulatory mechanisms. However, it is not uncommon for the elderly person to have a body temperature below 36.4° C (97.6° F). The normal temperature decreases with age.
Environment Normally, variations in environmental temperature do not affect the core temperature. However, exposure to extreme hot or cold temperatures can alter body temperature. If an individual’s core temperature falls to 25° C (77° F), death may occur.
Time of day Body temperature normally varies throughout the day. Typically, an individual’s temperature is lowest around 3:00 am and highest between 5:00 pm and 7:00 pm. Approximately 95% of patients have their highest temperature around 6:00 pm. Body temperature often fluctuates by as much as 2° C (1.8° F) between early morning and late afternoon.
Exercise Body temperature increases with exercise because exercise increases heat production as the body breaks down carbohydrates and fats to provide energy. During strenuous exercise, the body temperature can increase to as high as 40° C (104° F).
Stress Physical or emotional stress may increase body temperature because stress can stimulate the sympathetic nervous system, causing the epinephrine and norepinephrine levels to increase. When this occurs, the metabolic rate increases, causing an increased heat production. Stress and anxiety may cause a patient’s temperature to increase without underlying disease.
Hormones Women normally have greater fluctuations in temperature than do men. The female hormone progesterone, which is secreted during ovulation, causes the temperature to increase 0.3° to 0.6° C (0.5° to 1° F). After menopause, women have the same mean temperature norms as men.


Body Temperature Measurement


The measurement of body temperature establishes an essential baseline for clinical comparison as a disease progresses or as therapies are administered. To ensure the reliability of a temperature reading, the practitioner must (1) select the correct measuring equipment, (2) choose the most appropriate site, and (3) use the correct technique or procedure. The four most commonly used sites are the mouth, rectum, ear (tympanic), and axilla. Any of these sites is satisfactory when proper technique is used.


Additional measurement sites include the esophagus and pulmonary artery. Temperatures measured at these sites and in the rectum and at the tympanic membrane are considered core temperatures. The skin, typically that of the forehead or abdomen, may also be used for general temperature purposes. However, practitioners must remember that although skin temperature–sensitive strips or disposable paper thermometers may be satisfactory for general temperature measurements, the patient’s precise temperature should always be confirmed—when indicated—with a glass or tympanic thermometer.


Because body temperature is usually measured orally, the practitioner must be aware of certain external factors that can lead to false oral temperature measurements. For example, drinking hot or cold liquids can cause small changes in oral temperature measurements. The most significant temperature changes have been reported after a patient drinks ice water. Drinking ice water may lower the patient’s actual temperature by 0.2° to 1.6° F. Before taking an oral temperature, the practitioner should wait 15 minutes after a patient has ingested ice water. Oral temperature may increase in the patient receiving heated oxygen aerosol therapy and decrease in the patient receiving a cool mist aerosol. Table 2-3 lists the body temperature sites, their advantages and disadvantages, and the equipment used.



Table 2-3


Body Temperature Measurements: Sites, Normal Values, Advantages and Disadvantages, and Equipment Used

























Site and Temperature Advantages and Disadvantages Equipment
Oral (most common) Average 37° C or 98.6° F
Glass mercury thermometer, electronic thermometers
RectalAverage 0.7° C or 0.4° F higher than oral
Glass mercury thermometer
Tympanic thermometer
AxillaryAverage 0.6° C or 1° F lower than oral
Glass mercury thermometer


image



Pulse


A pulse is generated through the vascular system with each ventricular contraction of the heart (systole). Thus a pulse is a rhythmic arterial blood pressure throb created by the pumping action of the ventricular muscle. Between contractions, the ventricle rests (diastole) and the pulsation disappears. The pulse can be assessed at any location where an artery lies close to the skin surface and can be palpated against a firm underlying structure, such as muscle or bone. Nine common pulse sites are the temporal, carotid, apical, brachial, radial, femoral, popliteal, pedal (dorsalis pedis), and posterior tibial area (Figure 2-2).


image
FIGURE 2-2 The nine common pulse sites.

In clinical settings the pulse is usually assessed by palpation. Initially the practitioner uses the first, second, or third finger and applies light pressure to any one of the pulse sites (e.g., carotid or radial artery) to detect a pulse with a strong pulsation. After locating the pulse, the practitioner may apply a more forceful palpation to count the rate, determine the rhythm, and evaluate the quality of pulsation. The practitioner then counts the number of pulsations for 15, 30, or 60 seconds and then multiplies appropriately to determine the pulse per minute. Shorter time intervals may be used for patients with normal rates or regular cardiac rhythms.


In patients with irregular, abnormally slow, or fast cardiac rhythms, the pulse rates should be counted for 1 minute. To prevent overestimation for any time interval, the practitioner should count the first pulsation as zero and not count pulses at or after the completion of a selected time interval. Counting even one extra pulsation during a 15-second interval leads to an overestimation of the pulse rate by 4. The characteristics of the pulse are described in terms of rate, rhythm, and strength.



Rate


The normal pulse rate (or heart rate) varies with age. For example, in the newborn the normal pulse rate range is 100 to 180 beats per minute (bpm). In the toddler the normal range is 80 to 130 bpm. The normal range for the child is 65 to 100 bpm, and the normal adult range is 60 to 100 bpm (see Table 2-1).


A heart rate lower than 60 bpm is called bradycardia. Bradycardia may be seen in patients with hypothermia and in physically fit athletes. The pulse may also be lower than expected when the patient is at rest or asleep or as a result of head injury, vomiting, or advanced age. A pulse rate greater than 100 bpm in adults is called tachycardia. Tachycardia may occur as a result of hypoxemia, anemia, fever, anxiety, emotional stress, fear, hemorrhage, hypotension, dehydration, shock, and exercise. Tachycardia also is a common side effect in patients receiving certain medications, such as sympathomimetic agents (e.g., adrenaline or dobutamine).




Strength


The quality of the pulse reflects the strength of left ventricular contraction and the volume of blood flowing to the peripheral tissues. A normal left ventricular contraction combined with an adequate blood volume will generate a strong, throbbing pulse. A weak ventricular contraction combined with an inadequate blood volume will result in a weak, thready pulse wave. An increased heart rate combined with a large blood volume will generate a full, bounding pulse.


Several conditions may alter the strength of a patient’s pulse. For example, heart failure can cause the strength of the pulse to vary every other beat while the rhythm remains regular. This condition is called pulsus alternans. The practitioner may detect a pulse that decreases markedly in strength during inspiration and increases back to normal during exhalation, a condition called pulsus paradoxus that is common among patients experiencing a severe asthmatic episode. This phenomenon can also be heard when blood pressure is measured.


Finally, the stimulation of the sympathetic nervous system increases the force of ventricular contraction, increasing the volume of blood ejected from the heart and creating a stronger pulse. Stimulation of the parasympathetic nervous system decreases the force of the ventricular contraction, thus leading to a decreased volume of blood ejected from the heart and a weaker pulse. Clinically the strength of the pulse may be recorded on a scale of 0 to 4+ (Box 2-3).



Box 2-3   Scale to Rate Pulse Quality




For peripheral pulses that are difficult to detect by palpation, an ultrasonic Doppler device may also be used. A transmitter attached to the Doppler is placed over the artery to be assessed. The transmitter amplifies and transmits the pulse sounds to an earpiece or to a speaker attached to the Doppler device. The heart rate can also be obtained through auscultation by placing a stethoscope over the apex of the heart.



Respiration


The diaphragm is the primary muscle of respiration. Inspiration is an active process whereby the diaphragm contracts and causes the intrathoracic pressure to decrease. This action, in turn, causes the pressure in the airways to fall below the atmospheric pressure, and air flows in. At the end of inspiration, the diaphragm relaxes and the natural lung elasticity (recoil) causes the pressure in the lung to increase. This action, in turn, causes air to flow out of the lung. Under normal circumstances, expiration is a passive process.


The normal respiratory rate varies with age. For example, in the newborn the normal respiratory rate varies between 30 and 60 breaths per minute. In the toddler, the normal range is 25 to 40 breaths per minute. The normal range for the preschool child is 20 to 25 breaths per minute, and the normal adult range is 12 to 20 breaths per minute (see Table 2-1).


Ideally the respiratory rate should be counted when the patient is not aware. One good method is to count the respiratory rate immediately after taking the pulse, while leaving the fingers over the patient’s artery. As respirations are being counted, the practitioner should observe for variations in the pattern of breathing. For example, an increased breathing rate is called tachypnea. Tachypnea is commonly seen in patients with fever, metabolic acidosis, hypoxemia, pain, or anxiety. A respiratory rate below the normal range is called bradypnea. Bradypnea may occur with hypothermia, head injuries, and drug overdose. Table 2-4 provides an overview of common normal and abnormal breathing patterns.




Blood Pressure


The arterial blood pressure is the force exerted by the circulating volume of blood on the walls of the arteries. The pressure peaks when the ventricles of the heart contract and eject blood into the aorta and pulmonary arteries. The blood pressure measured during ventricular contraction (cardiac systole) is the systolic blood pressure. During ventricular relaxation (cardiac diastole), blood pressure is generated by the elastic recoil of the arteries and arterioles. This pressure is called the normal and diastolic blood pressure.


The normal blood pressure in the aorta and large arteries varies with age. For example, in the newborn the normal systolic blood pressure range is 60 to 180 mm Hg. In the toddler the normal range is 80 to 110 mm Hg. The normal range for the child is 100 to 110 mm Hg, and the normal adult range is 110 to 140 mm Hg (see Table 2-1). The numeric difference between the systolic and diastolic blood pressure is the pulse pressure. For example, a systolic pressure of 120 mm Hg and a diastolic pressure of 80 mm Hg equal a pulse pressure of 40 mm Hg.


Blood pressure is a function of (1) the blood flow generated by ventricular contraction and (2) the resistance to blood flow caused by the vascular system. Thus blood pressure (BP) equals flow (image) multiplied by resistance: BP = image + R.



Blood Flow


Blood flow is equal to cardiac output. Cardiac output is equal to the product of (1) the volume of blood ejected from the ventricles during each heartbeat (stroke volume) multiplied by (2) the heart rate. Thus a stroke volume (SV) of 75 mL and a heart rate (HR) of 70 bpm produce a cardiac output (CO) of 5250 mL/minute, or 5.25 L/min (CO = SV × HR). The average cardiac output in the resting adult is about 5 L/min.


A number of conditions can alter stroke volume and therefore blood flow. For instance, a decreased stroke volume may develop as a result of poor cardiac pumping (e.g., ventricular failure) or as a result of a decreased blood volume (e.g., during severe hemorrhage). Bradycardia may also reduce cardiac output and blood flow. Conversely, an increased heart rate or blood volume will likely increase cardiac output and blood flow. In addition, an increased heart rate in response to a decreased blood volume (or stroke volume) may also occur as a compensatory mechanism to maintain normal cardiac output and blood flow.



Resistance


The friction between the components of the blood ejected from the ventricles and the walls of the arteries results in a natural resistance to blood flow. Friction between the blood components and the vessel walls is inversely related to the dimensions of the vessel lumen (size). Thus as the vessel lumen narrows (or constricts), resistance increases. As the vessel lumen widens (or relaxes), the resistance decreases. The autonomic nervous system monitors and regulates the vascular tone.


Table 2-5 presents factors that affect the blood pressure.



Table 2-5


Factors Affecting Blood Pressure

































Age Blood pressure gradually increases throughout childhood, and correlates with height, weight, and age. In the adult, the blood pressure tends to gradually increase with age.
Exercise Vigorous exercise increases cardiac output and thus blood pressure.
Autonomic nervous system Increased sympathetic nervous system activity causes an increased heart rate, an increased cardiac contractility, changes in vascular smooth muscle tone to enhance blood flow to vital organs and skeletal muscles, and an increased blood volume. Collectively, these actions cause an increased blood pressure.
Stress Stress stimulates the sympathetic nervous system and thus can increase blood pressure.
Circulating blood volume A decreased circulating blood volume, either from blood or fluid loss, causes blood pressure to decrease. Common causes of fluid loss include abnormal, unreplaced fluid losses such as in diarrhea or diaphoresis, and overenthusiastic use of diuretics. Inadequate oral fluid intake can also result in a fluid volume deficit. Excess fluid, such as in congestive heart failure, can cause the blood pressure to increase.
Medications Any medication that affects one or more of the previous conditions may cause blood pressure changes. For example, diuretics reduce blood volume; cardiac pharmaceuticals may increase or decrease heart rate and contractility; pain medications may reduce sympathetic nervous system stimulation; and specific antihypertension agents may exert their effects as well.
Normal fluctuations Under normal circumstances, blood pressure varies from moment to moment in response to a variety of stimuli. For example, an increased environmental temperature causes blood vessels near the skin surface to dilate, causing blood pressure to decrease. In addition, normal respirations alter blood pressure: Blood pressure increases during expiration and decreases during inspiration. Blood pressure fluctuations caused by inspiration and expiration may be significant during a severe asthmatic episode.
Race Black males over 35 years of age often have elevated blood pressures.
Obesity Blood pressure is often higher in overweight and obese individuals.
Daily variations Blood pressure is usually lowest early in the morning, when the metabolic rate is lowest.


Abnormalities



Hypertension

Hypertension is the condition in which an individual’s blood pressure is chronically above normal range. Whereas blood pressure normally increases with aging, hypertension is considered a dangerous disease and is associated with an increased risk of morbidity and mortality. According to the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure, the physician may make the diagnosis of hypertension in the adult when an average of two or more diastolic readings on at least two different visits is 90 mm Hg or higher or when the average of two or more systolic readings on at least two visits is consistently higher than 140 mm Hg.


An elevated blood pressure of unknown cause is called primary hypertension. An elevated blood pressure of a known cause is called secondary hypertension. Factors associated with hypertension include arterial disease, obesity, a high serum sodium level, pregnancy, obstructive sleep apnea, and a family history of high blood pressure. The incidence of hypertension is higher in men than in women and is twice as common in blacks as in whites. People with mild or moderate hypertension may be asymptomatic or may experience suboccipital headaches (especially on rising), tinnitus, light-headedness, easy fatigability, and cardiac palpitations. With sustained hypertension, arterial walls become thickened, inelastic, and resistant to blood flow. This process in turn causes the left ventricle to distend and hypertrophy. Hypertension may lead to congestive heart failure.



Hypotension

Hypotension is said to be present when the patient’s blood pressure falls below 90/60 mm Hg. It is an abnormal condition in which the blood pressure is not adequate for normal perfusion and oxygenation of vital organs. Hypotension is associated with peripheral vasodilation, decreased vascular resistance, hypovolemia, and left ventricular failure. Hypotension can also be caused by analgesics such as meperidine hydrochloride (Demerol) and morphine sulfate, severe burns, prolonged diarrhea, and vomiting. Signs and symptoms include pallor, skin mottling, clamminess, blurred vision, confusion, dizziness, syncope, chest pain, increased heart rate, and decreased urine output. Hypotension is life threatening.


Orthostatic hypotension, also called postural hypotension, occurs when blood pressure quickly drops as the individual rises to an upright position or stands. Orthostatic hypotension develops when the peripheral blood vessels—especially in central body organs and legs—are unable to constrict or respond appropriately to changes in body positions. Orthostatic hypotension is associated with decreased blood volume, anemia, dehydration, prolonged bed rest, and antihypertensive medications. The assessment of orthostatic hypotension is made by obtaining pulse and blood pressure readings when the patient is in the supine, sitting, and standing positions.



Pulsus Paradoxus


Pulsus paradoxus is defined as a systolic blood pressure that is more than 10 mm Hg lower on inspiration than on expiration. This exaggerated waxing and waning of arterial blood pressure can be detected with a sphygmomanometer or, in severe cases, by palpating the pulse at the wrist or neck. Commonly associated with severe asthmatic episodes, pulsus paradoxus is believed to be caused by the major intrapleural pressure swings that occur during inspiration and expiration. The reason for this phenomenon is described in the following sections.





Oxygen Saturation


Oxygen saturation, often considered the fifth vital sign, is used to establish an immediate baseline Spo2 value. It is an excellent monitor by which to assess the patient’s response to respiratory care interventions. In the adult, normal Spo2 values range from 95% to 99%. Spo2 values of 91% to 94% indicate mild hypoxemia. Mild hypoxemia warrants additional evaluation by the respiratory practitioner but does not usually require supplemental oxygen. Spo2 readings of 86% to 90% indicate moderate hypoxemia. These patients often require supplemental oxygen. Spo2 values of 85% or lower indicate severe hypoxemia and warrant immediate medical intervention, including the administration of oxygen, ventilatory support, or both. Table 2-6 presents the relationship of Spo2 to Pao2 for the adult and newborn. Table 2-7 provides an overview of the signs and symptoms of inadequate oxygenation.




Table 2-7


Signs and Symptoms of Inadequate Oxygenation









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Jun 11, 2016 | Posted by in RESPIRATORY | Comments Off on The Physical Examination and Its Basis in Physiology

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