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Chapter 36 • Weight Loss/Gain (Unintentional) 441
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Note General Appearance
Observe the patient entering the room. Especially note
the t of clothing as well as general hygiene and signs
of stress or anxiety.
When examining an infant, observe interaction with
the caregiver. Failure-to-thrive infants may avoid eye
contact, show a lack of smiling or sounds, and have
poor interaction with their environment. The infant
may also prefer not to be cuddled and be difcult to
comfort, and may appear withdrawn even from the
caregiver.
Take Vital Signs
Vital signs will provide information on cardiovascular
and respiratory function. Height and weight can be compared to actuarial tables to see norms for weight by age
and gender. Calculate BMI. Bradycardia may indicate
hypothyroidism; tachycardia may indicate anemia, dehydration, or hyperthyroidism. Fever may indicate infection.
Weigh and Measure Newborn
A decrease in weight of more than 8% necessitates
followup within 48 hours, and a bilirubin level should
be drawn to assess for hyperbilirubinemia. A loss of
more than 10% of birth weight warrants careful assessment of possible causes and consideration of admission to the hospital.
Assess Mental Status
The major cognitive changes to detect as related to
weight loss or gain are dementia and depression (see
Chapter 8). Dementia can be assessed using the miniMMSE (see Figure 8-1) and distinguished from depression (see Box 8-1). Screen for the presence of an eating
disorder.
Examine the Head and Neck
Assess the head and neck for presence of lymphadenopathy. Moon facies indicates Cushing syndrome.
Palpate the thyroid for masses or asymmetry.
Assess the condition of the teeth and gums. Test the
patient’s ability to swallow using water or test for the
gag reex. Patients with diabetes may have xanthomas
associated with hyperlipidemia.
Examine the Abdomen
Observe for contour. Patients with diabetes tend
to have truncal obesity. Redistribution of fat in older
patients may also cause them to have truncal obesity.
Palpate for tenderness or lumps, auscultate for bowel
sounds, and check for rebound tenderness. Patients
with malabsorption may have ascites.
Examine the Extremities
Conduct a musculoskeletal exam to assess strength,
mobility, and balance (see Chapter 20). Assess for loss of
muscle mass and subcutaneous fat associated with
cachexia, malabsorption, and aging. Patients with hypothyroidism may have generalized edema and delayed
recovery of deep tendon reexes. Patients with hyperthyroidism may have overly brisk deep tendon reexes.
Patients with diabetes may have peripheral neuropathy.
Complete Blood Count with Indices
and Differential
A complete blood count (CBC) with indices will provide information about the degree and cause of anemia;
microcytic hypochromic anemia reects chronic blood
loss and normocytic normochromic anemia suggests
acute blood loss. The white blood cell (WBC) count
indicates the presence of inammation or infection (see
Chapter 34).
Conduct a Comprehensive Physical
Examination
Assess the Skin
Examine the skin for intactness, turgor, and presence of
lesions to determine hydration status and overall nutrition status. Hypothyroidism is associated with dry, aky
skin; skin darkening occurs with Addison disease.
Assess the Heart
Palpate the anterior thorax for the point of maximal
impulse (PMI), lifts, and heaves. Auscultate for adventitious sounds (see Chapter 7).
Fasting Blood Glucose
A fasting blood glucose (FBG) is a blood specimen taken
at least 2 hours after a meal. The normal value for fasting
FBG is below 100 mg/dL of glucose; an FBG of 100 to
125 mg/dL of glucose indicates pre-diabetes. If a random
blood glucose is obtained within 2 hours after a meal, a
normal value is 140 mg/dL or below.
Glycosylated Hemoglobin (A1c)
Glycosylated hemoglobin (A1c) reects the average
blood glucose over a 3-month period. A normal value is
below 7%. The A1c result is not dependent on when the
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most recent meal was consumed, but the results may be
affected by the presence of anemia or sickle cell disease.
The A1c result may be a poor reection of blood glucose
when severe anemia or sickle cell disease is present.
Thyroid-Stimulating Hormone
An elevated serum thyroid-stimulating hormone (TSH)
level identies hypothyroidism. A low or indetectable
level indicates hyperthyroidism.
Bilirubin
Bilirubin values are usually reported as two fractions:
conjugated (direct) and unconjugated (indirect). Conjugated hyperbilirubinemia is present if .50% of elevated total bilirubin is the conjugated form. Normal
total conjugated bilirubin in newborns is ,2 mg/dL;
the level peaks to 12.9 mg/dL at 3 to 4 days of life
and then decreases. A tool designed to help clinicians
assess the risks of the development of hyperbilirubinemia in newborns over 35 weeks gestational age can be
found at http://www.bilitool.com. Cystic brosis can
lead to liver failure and hyperbilirubinemia.
Total Serum Protein
A total serum protein measures the amount of total protein and albumin (from the liver) and globulin (from the
liver and immune system) in the blood. Normally there is
more albumin than globulin with a ratio of .1. Albumin
checks kidney function and reects dietary protein.
Elevated globulin may indicate infection.
Sweat Chloride Test
The quantitative pilocarpine iontophoresis test measures the amount of chloride and sodium in the sweat
of patients with cystic brosis. Normal sweat contains ,60 mEq/L of chloride and sodium. Two tests
on different occasions are needed for accurate diagnosis of cystic brosis.
Urinalysis
The extent of diagnostic investigation of urine will
depend on history and physical examination ndings.
Dipstick urinalysis can point out infection, proteinuria,
and glycosuria (see Chapter 32).
Fecal Occult Blood Testing
The fecal occult blood test (FOBT) is an initial screening method to detect gastrointestinal bleeding (see
Chapter 26).
Chest Radiograph
A chest x-ray can reveal the presence of consolidation,
lesions of the lung, and heart contour.
Tests of the Gastrointestinal Tract
A barium upper gastrointestinal (GI) series is used to
examine the upper GI region, but small lesions may not
be detected. Any abnormality needs to be evaluated by
endoscopy. The lower GI tract is evaluated using sigmoidoscopy or colonoscopy. A colonoscopy will detect
the presence of polyps and lesions along the entire
large intestine (see Chapter 2).
Computed Tomography
Computed tomography (CT) scanning can be done on
different body regions. Abdominal CT examines the
uterus, pancreas, GI tract, and other abdominal organs.
Mammography
Screening mammograms consist of two views—
craniocaudal (CC) and medial lateral oblique (MLO)—
to detect nonpalpable breast lesions. Compare results
to previous screening mammograms (see Chapter 5).
Pap Test
The Pap test is designed to detect cancer cells in the
cervix and vagina. A Pap test is generally recommended by age 18 years or in sexually active females,
and is repeated every 3 to 5 years depending on the
patient’s age and history.
Metabolic Rate
Estimated energy needs should be based on resting or
basal metabolic rate (BMR). BMR decreases with age
and with the loss of lean body mass. An equation using
actual weight, height, gender, and age is the most
accurate for estimating BMR and calculating daily
caloric requirements (Box 36-3).
DIFFERENTIAL DIAGNOSIS
Unintentional Weight Loss
Cancer
Cancer alters the body’s appetite signals and metabolism
resulting in cachexia, a condition in which body fat
stores are depleted and muscle mass decreases. The most
common malignancies that cause weight loss are gastrointestinal, lung, hematologic, and musculoskeletal. As
many as 40% of people with cancer reported unexplained
Chapter 36 • Weight Loss/Gain (Unintentional) 443
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Box 36-3
Women
Men
Basal Metabolic Rate (BMR) Formula
BMR 5 655 1 (4.35 3 weight in pounds) 1 (4.7 3 height in inches) 2 (4.7 3 age in years)
BMR 5 66 1 (6.23 3 weight in pounds) 1 (12.7 3 height in inches) 2 (6.8 3 age in years)
weight loss at the time of diagnosis. Some people notice
weight loss despite a good appetite. Others lose their
appetite and may even become nauseated by food or
have difculty swallowing.
Nutritional Status
Nutritional status is assessed by obtaining a history of
dietary habits and physical activity patterns, as well as
anthropometric measures (such as height and weight to
calculate BMI, and waist and hip circumference to determine distribution of body fat). Poor or inadequate nutrition
in severe forms is most often found in developing countries
and is manifested in two forms: kwashiorkor, which is
a protein deciency, and marasmus, which is caused by
inadequate food intake. Weight loss not explained by
dietary intake is most likely due to systemic disease.
Endocrine Disorders
Diabetes mellitus. In the U.S. and worldwide,
more than 90% of cases of diabetes are type 2. Type 1
diabetes is more often associated with weight loss despite increased appetite. Persons with type 2 diabetes
may experience increased thirst and urinary frequency
but often are asymptomatic. Some symptoms, such as
blurred vision or peripheral neuropathy, may reect
long term manifestations of an undiagnosed disease.
Despite weight loss, patients tend to exhibit central
obesity.
Hyperthyroidism. Patients with hyperthyroidism
may report palpitations, nervousness, emotional lability, fatigue, muscle weakness, weight loss despite good
appetite, hyperdefecation, heat intolerance, menstrual
changes (oligo-amenorrhea), increased appetite, insomnia, and tremors. On physical examination, exophthalmos, warm skin, onycholysis, increased sweating,
and thinning hair may be evident. Patients may have
localized myxedema (edematous skin thickening) of
legs (pretibial) or dorsa of feet. The thyroid may be
enlarged and a bruit may be present. Deep tendon
reexes (DTRs) may be brisk. High fever, congestive
heart failure, and mental status changes suggest thyroid
storm. TSH level will be low or indetectable.
Addison disease. Addison disease is a disorder that
occurs when the adrenal glands do not produce enough
of their hormones. Associated symptoms may include
changes in blood pressure or heart rate, darkening of the
skin, weakness, salt craving, and loss of appetite.
Malabsorption
Malabsorption is a condition where absorption and digestion of nutrients is disrupted. The disorder is caused by an
insufciency of a variety of digestive enzymes. In celiac
disease, there is an immunologic response to gluten. The
degree of weight loss varies and is accompanied by
chronic diarrhea and growth retardation. Patients exhibit
muscle wasting and loss of subcutaneous fat. In the presence of severe hypoproteinemia, ascites may be present.
Anorexia Nervosa
Anorexia most often affects young females who, despite
weight loss, have a self-image of being overweight and an
intense fear of gaining weight. Diagnosis is based on a body
weight 15% below what is expected, a distorted body image,
and the absence of at least three menstrual periods. Examination demonstrates loss of body fat, and dry, scaly skin.
Depression or Anxiety
Mood regulation through eating is a way some individuals cope with depression or anxiety (see Chapter 3).
Major depression is diagnosed by the presence of a
depressed mood or loss of interest or pleasure in usual
activities. Bipolar disorder involves episodes of mania
or hypomania, often followed by depression. In mania,
the patient experiences an elevated or irritable mood,
often described as a “high” (see Chapter 3).
Cognitive Impairment
Dementia or compromised cognitive function can disrupt normal self-regulation of appetite and hunger (see
Chapter 8). Dementia is a nonspecic syndrome in
444 Chapter 36 • Weight Loss/Gain (Unintentional)
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which affected areas of cognition may include memory,
attention, language, and problem solving. When it occurs early in life it is labeled as organic brain syndrome.
In the elderly, dementia has a rate of memory and
cognitive loss that exceeds that of normal aging (see
Chapter 8).
Psychosocial Factors (Alcohol Use, Social
Isolation, Economic Status)
Excessive alcohol intake may reduce appetite, which
can lead to poor nutrition. Individuals are generally
social beings and social isolation may reduce any motivation to prepare balanced meals or to eat when
alone. Older adults and young families may have nancial constraints in purchasing healthy foods, since fresh
fruits and vegetables cost more than fast foods and
snack foods (see Chapter 3).
HIV/AIDS
Acquired immune deciency syndrome (AIDS) is a
disease of the immune system caused by the human
immunodeciency virus (HIV). This condition progressively reduces the effectiveness of the immune
system and leaves individuals susceptible to opportunistic infections and tumors. HIV is transmitted
through direct contact of a mucous membrane or
the bloodstream with a bodily uid containing HIV,
such as blood, semen, vaginal uid, preseminal uid,
and breast milk. Persons with HIV infection develop
opportunistic infections due to their impaired immune response, and often have systemic symptoms
of infection such as fevers, sweats (particularly
at night), swollen glands, chills, weakness, and
weight loss.
Gastroesophageal Reflux in Infants
Regurgitation is commonly seen in newborns and
young infants while feeding. Immature upper gastrointestinal motility is thought to be the cause. Excessive reux may cause caloric deprivation resulting in
weight loss.
Crohn Disease
Crohn disease is an inammatory bowel disease that
presents with abdominal cramping, rectal bleeding,
and bloody diarrhea. Weight loss is common because
of malabsorption. There is a genetic link in families
with a two- to four-fold increase in risk when a rstdegree relative has the disease. The disease can affect
any part of the tract from the mouth to the anus. Disease affecting the small bowel affects nutritional status
and weight loss.
Tuberculosis
Tuberculosis is caused by Mycobacterium tuberculosis
and is spread by droplets through the respiratory tract (see
Chapter 10). Weight loss is a common symptom of tuberculosis. Diagnosis is based on a positive sputum culture.
Cystic Fibrosis
Cystic brosis is an exocrine gland disorder that produces mucus blockage in major organs and is associated
with an autosomal recessive trait (see Chapter 10).
Growth retardation and weight loss are common symptoms of cystic brosis.
Unintentional Weight Gain
Energy Balance
A 24-hour food intake history is the rst approach to
assessing nutritional and caloric intake. A history of
physical activity or energy expenditure is done to
assess the balance between calories consumed and
energy expended.
Aging
In women, cessation of estrogen secretion during
menopause is associated with lower levels of progesterone, androgen, and testosterone, which can lead to
weight gain and greater truncal fat deposition.
Endocrine Disorders
Hypothyroidism. Hypothyroidism (myxedema) is
associated with weight gain and symptoms of cold intolerance, constipation, hoarseness, depression, and
fatigue. Physical examination reveals bradycardia, dry
skin, and delayed recovery of deep tendon reexes. A
TSH is elevated in primary hypothyroidism.
Cushing syndrome. Cushing syndrome is associ-
ated with weight gain. Diagnosis is made through the
presence of associated symptoms, glucose tolerance
tests, and the dexamethasone suppression test. Cushing syndrome is associated with central truncal obesity, moon facies, supraclavicular fat pads and thin
extremities.
Chapter 36 • Weight Loss/Gain (Unintentional) 445
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DIFFERENTIAL DIAGNOSIS OF Common Causes of Unintentional Weight
Loss/Gain
CONDITION HISTORY PHYSICAL FINDINGS DIAGNOSTIC STUDIES
Weight Loss
Cancer Loss of appetite None or may look cachectic Diagnostic imaging
studies, CT, MRI,
x-ray, CBC
Undernutrition Poor calorie/nutrient intake,
Diabetes mellitus Polyuria, polyphagia,
Gastroesophage-
al reflux (infants)
Addison disease Salt craving, fatigue Darkening of the skin Serum electrolytes,
Hyperthyroidism Tachycardia, heat intolerance,
Malabsorption Intolerance to gluten; chronic
Depression Loss of appetite and/or
Dementia Disorientation to person, time,
Anorexia nervosa Female to male 10:1,
Psychosocial
factors
Infection Fever, fatigue Redness or swelling of tissues or
Crohn disease Weight loss, fever, diarrhea,
Cystic fibrosis Weight loss, cough, chronic
Nonorganic
failure to thrive
Tuberculosis (TB) Contact with person who has
Weight Gain
Intake/energy
balance
Aging Menopause history; metabo-
error in formula preparation
polydipsia
History of regurgitation None Upper GI, barium swallow
sweating
diarrhea, growth retardation
interest in food
or place
perfectionist, high achiever,
amenorrhea
Alcohol consumption, social
isolation, financial resources
family history
diarrhea, positive family
history
Weight loss, maternal
isolation, maternal
depression
TB, travel to endemic area,
HIV
Excessive calorie intake;
inactivity
lism change
Loss of body mass Total serum protein
Truncal obesity; xanthomas FBG, hemoglobin A1c,
glucose tolerance test
24 hour urine for
aldosterone
Exophthalmos, warm skin,
onycholysis, thinning hair,
pretibial myxedema, enlarged
thyroid, brisk DTRs
Muscle wasting, loss of
subcutaneous fat; may have
ascites
None or may have poor personal
hygiene
None or loss of body mass; poor
personal hygiene
Cachexia, hair loss, dry skin,
orthostatic hypotension
None or poor personal hygiene
with chronic alcoholism
lymph nodes
Perirectal fissure, anal skin tag CBC, colonoscopy,
Digital clubbing, growth
retardation, weight loss
Decreased skin fold thickness,
decrease subcutaneous fat
Cough, weight loss PPD, HIV, chest x-ray
Generalized excess of
subcutaneous fat
Truncal obesity; loss of
peripheral subcutaneous fat;
loss of muscle mass
TSH, T
4
Colonoscopy, stool
culture, fecal fat
Thyroid function tests,
refer for psychological
evaluation
MMSE
Thyroid function tests,
serum electrolytes
Liver function tests
Blood or tissue culture,
CBC
barium enema, small
bowel follow-through
Sweat test
Normal labs in 98%
None
Serum estrogen level
Continued
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DIFFERENTIAL DIAGNOSIS OF Common Causes of Unintentional Weight
Loss/Gain—cont’d
CONDITION HISTORY PHYSICAL FINDINGS DIAGNOSTIC STUDIES
Hypothyroidism Cold intolerance, weight gain,
constipation; medication
history
Cushing
syndrome
CBC, complete blood count; CT, computed tomography; DTR, deep tendon reflex; FBG, fasting blood glucose; GI, gastrointestinal; HIV, human
immunodeficiency virus; MMSE, Mini Mental State Examination; MRI, magnetic resonance imaging; PPD, purified protein derivative; T4, thyroxine;
TSH, thyroid-stimulating hormone.
Thirst, polyuria Moon facies, truncal obesity, thin
Bradycardia, dry skin,
generalized edema, delayed
recovery of DTRs
extremities
TSH, T
4
FBG, dexamethasone
suppression test
REFERENCES AND READINGS
American Congress of Obstetricians and Gynecologists: ACOG an-
nounces new pap smear and cancer screening guidelines, 2010.
Available online at http://www.acog.org/acog_districts/dist_
notice.cfm?recno513&bulletin53161. Accessed July 28, 2010.
Austin J, Marks D: Hormonal regulators of appetite. Int J Pediatr
Endocrinol Epub, 2009.
Flegal KM, Carroll MD, Ogden CL, Curtin LR: Prevalence and
trends in obesity among US adults, 1999-2008, JAMA 303:235,
2010.
Maciosek MV, Cofeld AB, Edwards NM, Flottemesch TJ,
Goodman MJ, Solberg LI: Priorities among effective clinical
preventive services: Results of a systematic review and analysis,
Am J Prev Med Jul 31:52, 2006.
Healthallrefer.com: Symptoms guide: weight gain—unintentional.
Available online at http://health.allrefer.com/health/weight-gainunintentional-info.html#. Accessed January 6, 2010.
McPhee SJ, Papadakis MA: Current medical diagnosis & treatment,
ed 49. New York, 2010, Appleton & Lange.
Metalidis C, Knockaert DC, Bobbaers H, Vanderschueren S: Involuntary
weight loss. Does a negative baseline evaluation provide adequate
reassurance? Eur J Intern Med 19:345, 2008.
Reife CM: Involuntary weight loss, Med Clin North Am 79:299,
1995.
U.S. Department of Health and Human Services, U.S. Department
of Agriculture: Dietary guidelines for Americans, 2005. Available online at http://www.health.gov/dietaryguidelines/dga2005/
document/default.htm. Accessed March 26, 2010.
Diagnostic
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Imaging
An x-ray is a stream of high energy photons produced by an x-ray tube used for their penetrating power in radiography. The short wavelength produced by this light energy is
unique in that it penetrates opaque objects. Releasing the beam onto a photosensitive surface causes a photochemical reaction, which results in an image on the x-ray lm in conventional systems or on an image receptor in digital systems. For ease of reference, the
term “image” will be used throughout the chapter. The density of the material determines
the penetration of the light energy. The image is a result of the amount of x-rays being
absorbed by the density of the tissue/organ as it passes to the receptor. Two terms are used
to describe this absorption. The rst is radiolucent, which means there is no interference
with the ow of the x-ray particles. The result is a black or very dark image. The second
term is radiopaque; in this instance, something lies between the beam and the cassette that
causes the beam to absorb or disperse, thereby not allowing the beam to reach the cassette
and making the image appear white.
III
Decreasing density
(black)
Radiolucent Radiopaque
Gradations of gray result from variations in density of the tissue or organ. There are
four basic roentgen densities, and all images include one or more of these densities (see
Table 37-1). A chest image demonstrates all four densities: from the black of the air in the
lung tissue to the full white density of the rib bones. The densities of the objects result in
the shadows on the image.
The radiograph image is a two-dimensional shadow picture of a three-dimensional
object. Because the image is two-dimensional, it is important that the clinician think
three-dimensionally when viewing the image. This thinking requires knowledge of the
normal anatomy of the area being x-rayed and transference of this knowledge to the shadows on the image.
Chapters 37 and 38 address specic x-rays commonly used for diagnosis.
Increasing density
(white)
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37
The Chest X-ray
he chest x-ray is the most commonly performed diagnostic x-ray examination. It is
T
performed to evaluate the lungs, heart, and
chest wall. A chest image is typically the rst imaging
test used to help diagnose symptoms such as shortness of breath, persistent cough, trauma, chest pain,
and fever. Chest images are also used to diagnose and
monitor conditions such as pneumonia, lung cancer,
and congestive heart failure.
DIAGNOSTIC REASONING:
VIEWING THE CHEST IMAGE
What are the rst steps in reviewing
an image?
Key Questions (to self)
n Do the images being examined belong to the correct
patient?
n Do I have two views of the area being examined?
n Is the image correctly displayed on the view box?
n Are the images of good quality?
n Do I know the anatomy of the chest?
TABLE 37-1
DENSITY DESCRIPTION EXAMPLES
Gas (air) Black,
Fat Gray, less
Water Whitish, slightly
Metal All white,
From Kersten L: Comprehensive respiratory nursing, Philadelphia,
1989, Saunders.
448
Chest Image Densities
radiolucent
radiolucent
radiopaque
radiopaque
Lung tissue, trachea,
bronchi, gas in
stomach or intestine
Soft tissue around
muscle
Heart, blood vessels,
muscle, diaphragm
Calcium of ribs,
vertebrae, scapulae,
clavicles, other
bones, prostheses,
contrast media
Identification of Image and Patient
Before viewing an image it is important to verify that
the image being viewed is from the patient being evaluated. Pertinent information about the patient should be
found on the image in the upper corner and should be
veried.
Views
Frontal and lateral views. Generally, two images
are taken when examination of the chest is requested.
One is a frontal view; it is usually a posteroanterior
(PA) view, where the patient is standing 6 feet from the
cassette and the image is taken from back (posterior) to
front (anterior) (Figure 37-1, A). A second image is the
lateral view (Figure 37-1, B). In a lateral view, the patient is standing with the hands held above the head
and the lateral thorax is against the cassette. A left lateral view (where the left thorax is against the image
cassette) is usually ordered instead of a right lateral
view because it provides a better view of the area
behind the heart and the bases of the lower lungs.
Additional views are occasionally ordered for specic
reasons.
Anteroposterior (AP) chest image. This view is
created when the beam passes from the anterior to the
posterior surface of the chest and then onto the image.
Patients who are in bed or who cannot stand usually
have these images ordered. When viewing the AP images the heart and mediastinum appear larger because
they are located in the anterior chest, and in this position the chest is farther from the image cassette.
Expiration image. This type of image is ordered
when a pneumothorax is suspected. A maximum expiration by the patient will cause the lung tissue to compress. The lung tissue is then compared to the pleural
air. With a pneumothorax, the pleural air will occupy
more space.
Lateral decubitus image. This view is used to
assess uid and air levels in the pleural spaces. The
patient is lying on his or her side with the image cassette
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upright against the patient’s chest. The beam is sent
perpendicular to the image cassette. Air rises and uid
falls to the dependent area.
R
L
Oblique image. The oblique image is used to distinguish anterior from posterior lesions by avoiding
bony structures. It is also used for examining the trachea. Oblique images can be right or left obliques. In a
right oblique, the patient’s anterior right side is against
the image cassette.
Lordotic image. The lordotic image identies
right and left middle lung elds. The x-ray machine is
tilted to a 45-degree angle. This position offers a better
view of lung apices that can otherwise be obscured by
clavicles and upper ribs on the PA view.
Image Box Placement
Place the PA image on the lightened view box with the
patient’s left side facing the reader’s right side. The
image is labeled with an R or L. If there is no labeling,
look for the aortic arch. The arch is the rst bump seen
A
on the image and is on the patient’s left or the viewing
clinician’s right. In the rare patient with dextrocardia,
the reverse is true.
The left lateral image should be placed on the view
box such that the left side of the patient is facing the
reader.
B
FIGURE 37-1 Patient positioning for AP and left lateral
chest images. A, A patient positioned for a posteroanterior
projection of the chest. B, Proper patient position for a left
lateral chest view. Note the left side of the patient is placed
against the image receptor. (From Ballinger PW, Frank ED:
Merrill’s atlas of radiographic positions and radiographic
procedures, ed 10, Vol 1, St Louis, 2003, Mosby.)
Image Quality
The number of x-rays beamed through the patient onto
the image affects the details seen on the image. If not
enough beams were delivered, the image will be underexposed and appear lighter than normal. If too many
beams were delivered, the image will become overexposed and will be darker than normal. On the PA view,
thoracic vertebral bodies should be barely visible
through the heart shadow; on the lateral view, the
spinal bodies should be visible.
To obtain a good chest image, the x-ray is taken
with the patient in full inspiration. If the image is taken
on expiration or poor inspiration, the heart appears
larger and the lungs look cloudy. The 10 posterior ribs
above the diaphragm should be evident in a good quality image.
The angle of the beam should be direct and the
patient should be positioned properly. If the patient is
at an improper angle, the beam will be more scattered
and details will be lost. To determine if the patient is
positioned correctly, note the clavicles. The medial
heads of the clavicles should be positioned over the
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spine. If the heads are not centered, alignment may not
be correct, causing the image to be slightly oblique.
The costophrenic angle and the lateral lung elds
should be visible.
Reviewing Anatomy
Reviewing the normal anatomy of the structures of the
chest is helpful when learning how to interpret a chest
image.
Superimposing the anatomy onto a chest image will
help to correlate the normal structures to the shadows
(Figure 37-2).
What approach should be used when viewing
an image?
Key Questions (to self)
n What is your initial impression?
n Are you using a systematic examination technique?
Initial Impression
Most clinicians view images initially by standing 6 to
8 feet from the image and giving the image a onceover glance. The purpose of this activity is to observe
for any obvious abnormality as well as to obtain an
overall impression of the thorax for size, shape, and
symmetry.
Systematic examination of the image after an initial
overview is mandatory. All parts of the chest anatomy are
evaluated at 2 to 4 feet from the image, concentrating on
one part of the image at a time, to observe any abnormalities. A suggested systematic examination follows.
DIAGNOSTIC REASONING:
SYSTEMATIC EXAMINATION
How do I assess the PA view?
Soft Tissue
Examine the periphery of the image to evaluate the
amount of soft tissue present (for obesity or cachexia),
calcications, or gas collections indicating subcutaneous emphysema. Note the presence of breasts in female
patients. Be aware that breast tissue may cover the
lower lung elds.
Trachea
Located in the anterior mediastinum, the trachea should
be checked for size and position. The trachea will
appear deviated in a rotated patient. Abnormal pathological deviations may be a result of pressure on the mediastinum, including tumors, pneumothorax, or emphysema.
A mass will push the trachea away from midline. The
trachea will deviate toward a large pneumothorax and
A
FIGURE 37-2 Normal PA image. A, Unlabeled. B, A diagrammatic overlay showing the normal ana-
tomic structures numbered or labeled: 1, trachea; 2, right main brochus; 3, left main bronchus; 4, left
pulmonary artery; 5, right upper lobe pulmonary artery; 6, right interlobar artery; 7, right lower and
middle lobe vein; 8, aortic arch; 9, superior vena cava; 10, azygos vein. (From Fraser R (ed): Fraser and
Paré’s diagnosis of diseases of the chest, ed 4, Vol 1, Philadelphia, 1999, Saunders.)
SCAPULA
AXILLARY
FOLD
B
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