PROCEDURE	DESCRIPTIVE
Chest radiograph (X-ray)	Produces images of internal structures of chest, including air-filled lungs, airways, vascular markings, heart, and great vessels; shows heart size
Electrocardiography (ECG)	Graphic measure of electrical activity of heart
Holter monitor	24-hour continuous ECG recording used to assess dysrhythmias
Echocardiography	Use of high-frequency sound waves obtained by a transducer to produce an image of cardiac structures
Transthoracic	Performed with transducer on chest
M-mode	One-dimensional graphic view used to estimate ventricular size and function
Two-dimensional (2-D)	Real-time, cross-sectional views of heart used to identify cardiac structures and cardiac anatomy
Doppler	Identifies blood flow patterns and pressure gradients across structures
Fetal	Imaging fetal heart in utero
Transesophageal (TEE)	Transducer placed in esophagus behind heart to obtain images of posterior heart structures or in patients with poor images from chest approach
Cardiac catheterization	Imaging study using radiopaque catheters placed in a peripheral blood vessel and advanced into heart to measure pressures and oxygen levels in heart chambers and visualize heart structures and blood flow patterns
Hemodynamics	Measures pressures and oxygen saturations in heart chambers
Angiography	Use of contrast material to illuminate heart structures and blood flow patterns
Biopsy	Use of special catheter to remove tiny samples of heart muscle for microscopic evaluation; used in assessing infection, inflammation, or muscle dysfunction disorders; also used to evaluate for rejection after heart transplant
Electrophysiology (EPS)	Special catheters with electrodes employed to record electrical activity from within heart; used to diagnose rhythm disturbances
Exercise stress test	Monitoring of heart rate, blood pressure, electrocardiogram (ECG), and oxygen consumption at rest and during progressive exercise on a treadmill or bicycle
Cardiac magnetic resonance imaging (MRI)	Noninvasive imaging technique; used in evaluation of vascular anatomy outside of heart (e.g., coarctation of the aorta, vascular rings), estimates of ventricular mass and volume; uses for MRI are expanding

COMPLETE BLOOD CELL COUNT

TABLE 4-4 Complete Blood Cell Count

TEST (AVERAGE VALUE)	DESCRIPTION/COMMENTS
Red blood cell (RBC) count (4.5-5.5 million/mm³)	Number of RBCs/mm³ of blood Indirectly estimates Hgb content of blood Reflects function of bone marrow

Hemoglobin (Hgb) determination (11.5-15.5 g/dl)^*

Amount of Hgb (g)/dl of whole blood

Total blood Hgb primarily depends on number of circulating RBCs but also on amount of Hgb in each cell

Hematocrit (Hct) (35%-45%)

Percent volume of packed RBCs in whole blood

Indirectly measures Hgb content

Is approximately three times Hgb content

RBC indexes Mean corpuscular volume (MCV) (77-95 fl)

Average or mean volume (size) of a single RBC

MCV values are expressed as femtoliters (fl) or cubic microns (μm³)

Mean corpuscular hemoglobin (MCH) (25-33 pg/cell)

Average or mean quantity (weight) of Hgb in a single RBC

MCH values are expressed as picograms (pg) or micromicrograms (μmcg)

MCV and MCH depend on accurate counts of RBCs, whereas MCHC does not; therefore, MCHC is often more reliable.

All indexes depend on average cell measurements and do not show individual RBC variations (anisocytosis).

Mean corpuscular hemoglobin concentration (MCHC) (31%-37% Hgb [g]/dl RBC)

Average concentration of Hgb in a single RBC

MCHC values are expressed as percent Hgb (g)/cell or Hgb (g)/dl RBC.

RBC volume distribution width (RDW) (13.4% ± 1.2%)

Average size of RBCs

Differentiates some types of anemia

Reticulocyte count (0.5%-1.5% erythrocytes)

Percent reticulocytes in RBCs

Index of production of mature RBCs by bone marrow

Decreased count indicates depressed bone marrow function.

Increased count indicates erythrogenesis in response to some stimulus.

When reticulocyte count is extremely high, other forms of immature RBCs (normoblasts, even erythroblasts) may be present.

Indirectly estimates hypochromic anemia

Usually elevated in patients with chronic hemolytic anemia

White blood cell (WBC) count (4.5-13.5 × 10³ cells/mm³)

Number of WBCs/mm³ of blood

Total number of WBCs less important than differential count

Differential WBC count

Inspection and quantification of WBC types present in peripheral blood

Values are expressed as percentages; to obtain the absolute number of any type of WBC, multiply its respective percentage by total number of WBCs.

Neutrophils (polys) (54%-62%)

(3-5.8 × 10³ cells/mm³)

Primary defense in bacterial infection; capable of phagocytizing and killing bacteria Bands (3%-5%) (0.15-0.4 × 10³ cells/mm³)

Immature neutrophil

Increased numbers in bacterial infection

Also capable of phagocytosis and killing bacteria

Eosinophils (1%-3%) (0.05-0.25 × 10³ cells/mm³)

Named for their staining characteristics with eosin dye

Increased in allergic disorders, parasitic diseases, certain neoplasms, and other diseases

Basophils (0.075%) (0.015-0.030 × 10 cubed cells/mm³)

Named for their characteristic basophilic stippling

Contain histamine, heparin, and serotonin; believed to cause increased blood flow to injured tissues while preventing excessive clotting

Lymphocytes (25%-33%) (1.5-3.0 × 10³ cells/mm³) Involved in development of antibody and delayed hypersensitivity Monocytes (3%-7%) Large phagocytic cells that are involved in early stage of inflammatory reaction Absolute neutrophil count (ANC) (> 1000)

Percent neutrophils/bands times WBC count

Indicates body’s capability to handle bacterial infections

Platelet count (150-400 × 10³/mm³)

Number of platelets/mm³ of blood

Cellular fragments that are necessary for clotting to occur

Stained peripheral blood smear

Visual estimation of amount of Hgb in RBCs and overall size, shape, and structure of RBCs

Various staining properties of RBC

structures may be evidence of immature forms of erythrocytes

Shows variation in size and shape of RBCs: microcytic, macrocytic, poikilocytic (variable shapes)

^* Hemoglobin values may vary according to the child’s age and gender.

COMMON NEUROLOGIC TESTS

TABLE 4-5 Common Neurologic Tests

TEST	DESCRIPTION	PURPOSE
Lumbar puncture (LP)	Spinal needle is inserted between L3-L4 or L4-L5 vertebral spaces into subarachnoid space; cerebrospinal fluid (CSF) pressure is measured, and sample is collected for examination.	Diagnostic—measures spinal fluid pressure, obtains CSF for laboratory analysis; monitors for presence of bacteria (meningitis) Therapeutic—injection of medication (intrathecal)

Subdural tap Needle is inserted into anterior fontanel or coronal suture (midlineto pupil).

Helps rule out subdural effusions

Removes CSF to relieve pressure

Ventricular puncture Needle is inserted into lateral ventricle via coronal suture (midlineto pupil). Removes CSF to relieve pressure Electroencephalography (EEG)

EEG records changes in electric potential of brain.

Electrodes are placed at various points to assess electrical function in a particular area.

Impulses are recorded by electromagnetic pen or digitally.

Detects spikes, or bursts of electrical activity that indicate the potential for seizures

Used to determine brain death

Nuclear brain scan

Radioisotope is injected intravenously, and then counted and recorded after fixed time intervals.

Radioisotope accumulates in areas where blood-brain barrier is defective.

Identifies focal brain lesions (e.g., tumors, abscesses)

Positive uptake of material with encephalitis and subdural hematoma

Visualizes CSF pathways

Endocephalography Pulses of ultrasonic waves are beamed through head; echoes from reflecting surfaces are recorded graphically.

Identifies shifts in midline structures from their normal positions as a result of intracranial lesions

May show ventricular dilation

Real-time ultrasonography (RTUS) RTUS is similar to CT but uses ultrasound instead of ionizing radiation. Allows high-resolution anatomic visualization in variety of imaging planes Radiography Skull films are taken from different views—lateral, posterolateral, axial (submentoventricular), and half-axial.

Shows fractures, dislocations, spreading suture lines, craniostenosis

Shows degenerative changes, bone erosion, calcifications

Computed tomography (CT) scan

Pinpoint X-ray beam is directed on horizontal or vertical plane to provide series of images that are fed into computer and assembled in image displayed on video screen.

CT uses ionizing radiation.

Visualizes horizontal and vertical cross section of brain in three planes (axial, coronal, and sagittal)

Distinguishes density of various intracranial tissues and structures—congenital abnormalities, hemorrhage, tumors, demyelinating and inflammatory processes, calcification

Magnetic resonance imaging (MRI) MRI produces radiofrequency emissions from elements (e.g., hydrogen, phosphorus), which are converted to visual images by computer.

Permits visualization of morphologic feature of target structures

Permits tissue discrimination unavailable with many techniques

Positron emission to mography (PET) PET involves IV injection of positron-emitting radionucleotide; local concentrations are detected and transformed into visual display by computer. Detects and measures blood volume and flow in brain, metabolic activity, biochemical changes within tissue Digital subtraction angiography (DSA) Contrast dye is injected intravenously; computer “subtracts” all tissues without contrast medium, leaving clear image of contrast medium in vessels studied. Visualizes vasculature of target tissue Visualizes finite vascular abnormalities Single-photon emission computed tomography (SPECT) SPECT involves IV injection of photon-emitting radionuclide; radionuclides are absorbed by healthy tissue at a different rate than diseased or necrotic tissue; data are transferred to computer that converts image to film. Provides information regarding blood flow to tissues; analyzing blood flow to organ may help determine how well it is functioning.

PULMONARY FUNCTION TESTS

TABLE 4-6 Pulmonary Function Tests

TEST	MEASUREMENT	SIGNIFICANCE
Forced vital capacity (FVC) (peak flow)	Maximum amount of air that can be expired after maximum inspiration	Reduced in obesity Reduced in obstructive airway disease Normal in restrictive disease

Forced expiratory volume in 1 second (FEV₁) or 3 seconds (FEV₃) Amount of air that can be forced from lungs after maximum inspiration in 1 and 3 seconds

Normally 80% of FVC in 1 second

Reduced in obstructive disease

Is the single best measure of airway function

Tidal volume (TV or V_T) Amount of air inhaled and exhaled during any respiratory cycle

Multiplied by respiratory rate to provide minute volume

Information needed to determine rate and depth of artificial ventilation

Functional residual volume (FRV); functional residual Capacity (FRC) Volume of air remaining in lungs after passive expiration

Allows for aeration of alveoli

Increased in hyperinflated lungs of obstructive lung disease

Dynamic compliance Relationship between change in volume and pressure difference

Reflects elastic recoil of lung

Normal volume but decreased airflow in obstructive disease (e.g., asthma)

Normal flow but decreased volume in restrictive disease (e.g., pulmonary fibrosis)

Pulmonary resistance Changes in pressure with changes in flow on inspiration and expiration Work of breathing Total work expended moving lung and chest Respiratory time constancy Time for proximal and alveolar airway pressure to equilibrate Capnography Measures CO₂ during inhalation and exhalation cycle and produces a graph of CO₂ concentration over time Provides end-tidal CO₂ levels to determine trends and identify shunts FEV₁ or FEV₃/FVC Percentage of maximum inspiration that is expired in 1 or 3 seconds

Normally 95% of FVC in 3 seconds

Reduced in obstructive disease

RADIOLOGIC EXAMS

TABLE 4-7 Radiologic Exams

TEST	DESCRIPTION	PURPOSE
Radiography	Pictures obtained by passing X-rays through the body and recording them on sensitized film	Produces images of internal structures of chest, including air-filled lungs, airways, vascular markings, heart, and great vessels
Fluoroscopy	Projection of electronically intensified image on viewing screen	Used primarily to study diaphragmatic excursion and respiratory motion of lungs Examination of barium-filled esophagus to outline mediastinal abnormalities

Bronchography Contrast medium instilled directly into bronchial tree through opaque catheter inserted via orotracheal tube

Valuable to demonstrate and inspect bronchiectasis

Detects distal bronchial obstruction

Detects malformations

Barium swallow (or other contrast agent) Esophagus outlined when barium solution or colloid is swallowed

Esophageal displacement defining mediastinal masses

Detects swallowing disorders and malformations (e.g., tracheoesophageal fistula)

Angiography Injection of dye to produce image of pulmonary vasculature Investigation of pulmonary vascular anomalies and pulmonary hypertension Computed tomography (CT) Sequence of X-rays, each representing a cross section or “cut” through lung tissue at different depth Useful in identifying presence of calcium or cavity within a lesion, hilar adenopathy, mediastinal masses, or abnormalities KUB Flat plate roentgenogram of abdomen and pelvis for kidney, ureters, and bladder (KUB); intestine also included in child Visualizes gastrointestinal outline for air, masses, stool; problems such as intestinal obstruction Magnetic resonance imaging (MRI) Use of large magnet and radio waves to produce 2- or 3-dimensional image Clearly identifies soft tissues Radioisotope scanning Intravenous injection of albumin labeled with radioisotopes or inhalation of radioactive aerosols or xenon gas followed by radiation scanning

Delineates defects in pulmonary arterial perfusion and diseased areas of lungs

Detects location of aspirated foreign body

Ultrasonography Transmission of sound waves through chest Identifies opacification, internal structures, masses

UROLOGIC DIAGNOSTIC TESTS

TABLE 4-8 Urologic Diagnostic Tests

TEST	PROCEDURE	PURPOSE
Renal/bladder ultrasound	Transmission of ultrasonic waves through renal parenchyma, along ureteral course, and over bladder	Allows visualization of renal parenchyma, renal pelvis without exposure to external beam radiation or radioactive isotopes Visualization of dilated ureters and bladder wall also possible

Testicular (scrotal) ultrasound Transmission of ultrasonic waves through scrotal contents and testis

Allows visualization of scrotal contents, including testis

Testicular ultrasound is and Doppler-enhanced ultrasound is used to differentiate hyperemia of epididymo-orchitis from ischemia or torsion.

Scout film, (KUB) Flat plate roentgenogram of abdomen and pelvis for kidney, ureters, and bladder (KUB) Detects and establishes renal outlines, presence of calculi, or opaque foreign bodies in bladder Voiding cystourethrography Contrast medium injected into bladder through urethral catheter until bladder is full; films taken before, during, and after voiding Visualizes bladder outline and urethra, reveals reflux of urine into ureters, and shows complications of bladder emptying Radionuclide (nuclear) cystogram Radionuclide-containing fluid injected through urethral catheter until bladder is full; images generated before, during, and after voiding

Alternative to voiding cystourethrography in children with allergy to intravesical contrast material

Allows evaluation of reflux, although visualization of anatomic details is relatively poor

Radioisotope imaging studies Contrast medium injected intravenously; computer analysis to measure uptake or washout (excretion) for analysis of organ function

DTPA radioisotope used to measure glomerular filtration rate; estimate of differential renal function and renal washout to determine presence and location of upper urinary tract obstruction

DMSA radioisotope allows visualization of renal scars and differential renal function; ureters and bladder are not visualized.

MAG 3 radioisotope combines features of DTPA (evaluation of upper urinary tract obstruction) with features of DMSA radioisotope (differential renal function).

Intravenous pyelography (IVP) (intravenous urogram; excretory urogram)

Intravenous injection of a contrast medium

Medium secreted and concentrated by tubules

X-ray films made 5, 10, and 15 minutes after injection; delayed films (30, 60 minutes, and so on), are obtained if obstruction is suspected.

Defines urinary tract

Provides information about integrity of kidneys, ureters, and bladder

Visualizes retroperitoneal masses when they shift position of ureters

Computed tomography (CT) Narrow-beam x-rays and computer analysis provide precise reconstruction of area.

Visualizes vertical or horizontal cross section of kidney

Especially valuable to distinguish tumors and cysts

Cystoscopy Direct visualization of bladder and lower urinary tract through small scope inserted via urethra Investigation of bladder and lower tract lesions; visualizes ureteral openings, bladder wall, trigone, and urethra Retrograde pyelography Contrast medium injected through ureteral catheter Visualizes pelvic calyces, ureters, and bladder Renal angiography Contrast medium injected directly into renal artery via catheter placed in femoral artery (or umbilical artery in newborn) and advanced to renal artery Visualizes renal vascular system, especially for renal arterial stenosis Whitaker perfusion test

Injection of contrast material through renal pelvis and ureters

Pressures are measured in renal pelvis and urinary bladder.

Determine presence of obstruction causing upper urinary tract dilation Renal biopsy Removal of kidney tissue by open or percutaneous technique for study by light, electron, or immunofluorescent microscopy

Yields histologic and microscopic information about glomeruli and tubules; helps to distinguish between types of nephritic syndromes

Distinguishes other renal disorders

Urodynamics

Set of tests designed to measure bladder filling, storage, and evacuation functions

Uroflowmetry is a test to determine efficiency of urination.

Cystometrogram is a graphic comparison of bladder pressure as a function of volume.

Voiding pressure study is a comparison of detrusor contraction pressure, sphincter electromyelogram, and urinary flow.

Determines characteristic of voiding dysfunction

Used to identify type (cause) of incontinence or urinary retention

Especially valuable for voiding dysfunction complicated by urinary infection, urinary retention, or neurogenic bladder dysfunction

TABLE 4-9 Lumbar Puncturet †

CELL COUNT	CELLS/MM3
Preterm	0-25 mononuclear 0-10 polymorphonuclear 0-1000 RBC
Newborn	0-20 mononuclear 0-10 polymorphonuclear 0-800 RBC
Neonate	0-5 mononuclear 0-10 polymorphonuclear 0-50 RBC
Thereafter	0-5 mononuclear
LEUKOCYTE DIFFERENTIAL COUNT	PERCENT (%)
Lymphocytes	62±34
Monocytes	36±20
Neutrophils	2±5
Eosinophils	0-rare
Glucose	40-70 mg/dL^* (adult values)
Protein	8-32 mg/dL