X-RAY/PEDIATRIC POISONING
| DO WE REALLY NEED THAT X-RAY? —Gregory W. Hendey, MD, Associate Clinical Professor of Medicine and
Emergency Medicine, University of California, San Francisco, School of Medicine, and Medical Education Program,
Fresno, California
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| Radiographs in emergency departments (EDs): nationally, 108 million patients seen and 40 million radiographs taken
every year in EDs; only 2% to 10% of radiographs have positive findings; most x-rays done for medical reasons; intangible
reasons for getting x-rays include medicolegal concerns, special patients (eg, celebrities, physician or staff family
members), patient’s request; reducing number of radiographs reduces exposure to radiation, lowers total medical
costs, and saves time (assuming correct diagnosis easily made without radiograph)
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| Ankle and foot injuries: radiographs taken in \>90% of patients presenting to ED with ankle injuries; ≈10% of radiographs
positive for fracture; Ottawa ankle rule—study derived and validated rule for predicting 100% of clinically
significant fractures around ankle; use of rule leads to reduction in number of ankle radiographs by ≈33%; radiograph
necessary if patient cannot ambulate (ie, take 4 weight-bearing steps immediately after injury and in ED) or if tenderness
present at posterior edge or tip of medial or lateral malleolus; radiograph unnecessary in all other cases; Ottawa
foot rule—radiograph necessary if patient unable to ambulate or has tenderness over base of fifth metatarsal or over
navicular; independent validation—Ottawa foot and ankle rules highly sensitive but <100% (as in original study); ankle
radiographs decreased by 26% (McBride) and 16% (Verma et al); impact lower than in original study, suggesting
subjective influences in decision to x-ray
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| Knee injuries: radiographs taken in \>70% of patients who present to ED with knee injury; <10% of radiographs positive
for fracture; Pittsburg knee rule—small study derived and validated rule for predicting 100% of clinically significant
fractures of knee; use of rule reduced number of radiographs by ≈75%; radiograph necessary if injury caused by blunt
trauma or fall, if patient unable to ambulate (as defined in Ottawa ankle rule), or patient age <12 yr or \>50 yr; Ottawa
knee rule—large study; rule 100% sensitive for detecting fractures and reduces radiographs by ≈20%; radiograph
necessary if patient \>55 yr of age, has point tenderness at patella or head of fibula, unable to flex knee to 90° angle, or
unable to ambulate; comparison of rules—Pittsburgh group found both rules highly sensitive but Pittsburgh rule more
specific, ie, potentially could reduce radiographs to greater degree (but Pittsburgh had “home court advantage”)
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| Use of rules in clinical practice: survey of 1700 practicing emergency physicians in 2001 found \>90% of physicians
in United States, Canada, and United Kingdom aware of rules, but only 32% of physicians in United States used
them regularly (compared to 89% in Canada and 75% in United Kingdom)
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| Chest radiographs: decision rule for all patients with nontraumatic mechanisms of injury difficult because broad range
of problems could result in positive findings; pneumonia—2 studies looked at clinical indications for chest radiographs
in patients with suspected pneumonia; both showed importance of vital signs (studies used cutoff temperature
(T) of 37.8°C, heart rate of 100 beats/min, and respiratory rate of 20 breaths/min); most patients with pneumonia have
abnormal vital sign; another study found gestalt approach (decision based on overall examination and history) by physicians
more sensitive but somewhat less specific than guidelines established by decision rules; other factors to consider
include age and pulse oximetry (not addressed by studies); asthma—only 2% of adult patients with acute
exacerbations had abnormalities on chest radiographs; 13% of children had positive findings; other problems (eg, aspiration,
congenital heart defect, or pneumonia) common in children not previously diagnosed with asthma; chronic obstructive
pulmonary disease (COPD)—≈16% of patients have positive findings; radiograph helpful if patient sick or
not improving as expected; pneumothorax—study using blinded readers found inspiratory films as effective as expiratory
films for detecting pneumothorax; however, second film (inspiratory or expiratory) increases accuracy; single inspiratory
film sufficient to rule out pneumothorax in most patients
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| Traumatic aortic rupture: chest radiograph used for initial screening, but has limitations; common (sensitive)
findings—rarely, patient has no positive findings on radiograph; most patients have wide mediastinum or opacified
aortopulmonary window; specific (but not sensitive) findings—rib fractures; apical capping; depressed left mainstem
bronchus; deviated nasogastric tube; although presence indicates high likelihood of traumatic aortic rupture, specific
findings not seen in most patients; other imaging—although chest radiograph frequently abnormal, most patients do
not have traumatic aortic rupture; study looked at spiral computed tomography (CT) with timed contrast bolus as next-
step diagnostic test; of 1100 patients, 24 had aortic injury on CT; patients sent to surgery or angiography; 21 patients
had true aortic injury (ie, CT 100% sensitive, 97% specific, with few false positives); decision rule—no additional
tests necessary if no findings on CT (unless degree of clinical suspicion very high); aortic injury identified by CT requires
surgery or aortography; mediastinal hematoma against aorta warrants aortography; aortography not necessary if
hematomas located away from aorta (somewhat controversial)
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| Pelvis: radiographs routine part of Advanced Trauma Life Support (ATLS) protocol, but role questionable in patients with
moderate trauma; decision rule—radiographs obtained if patient has altered mental status, or if physical examination
reveals signs of injury to pelvis or back; selective protocol detected all pelvic fractures and reduced radiographs by 50%
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| Abdominal pain: most frequent presenting complaint in ED; in general, plain radiographs low yield; radiographs helpful
if bowel obstruction, free air, or foreign body suspected, but unlikely to aid diagnosis of patient with nonspecific
abdominal pain; plain radiographs detect only ≈50% of intra-abdominal pathologies; other imaging—CT more accurate
for detecting all intra-abdominal pathologies; potential exists for overuse; at present, no decision rules for use of
abdominal CT
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| Cervical spine: only ≈2% of radiographs taken in ED have positive findings; National Emergency X-radiography Utilization
Study (NEXUS)—large prospective multicenter trial developed decision rule; radiographs recommended if patient
has tenderness in posterior cervical spine, intoxication, altered mental status, neurologic deficit, or distracting painful injury
(ie, interferes with ability to examine neck); decision rule 99.6% sensitive, but specificity low (reduces radiographs
by only 13%); Canadian cervical spine rule—3-step decision rule, 100% sensitive and capable of reducing radiographs
by 59%; high-risk factors include age \>65 yr, paresthesias, and dangerous mechanism of injury (eg, accidents involving
rollover, ejection, high speed, or axial load to head); presence of high-risk factors requires radiograph; low-risk factors include
delayed onset of pain, ability to ambulate at scene, and ability to sit up in ED; absence of low-risk factors warrants
radiograph; presence of low-risk factors indicates low likelihood of clinically significant injury and warrants assessment
of neck rotation; if rotation associated with spasm or pain, radiograph indicated; comparison of rules—Ottawa group
found Canadian rule more sensitive (99% vs 90%) and more specific (45% vs 36%) than NEXUS; again, home court advantage
possibly accounts for difference; conclusions—integration of components of both decision rules may aid in diagnosis;
degree of clinical suspicion helps interpret ambiguous results
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| Acute low back pain: typically benign self-limited disease that does not require testing or imaging; although rare, concern
about fractures, cancer, infection, lesion on spinal cord, or cauda equina; guidelines—look for red flags during
history and physical examination; perform diagnostic imaging (often, magnetic resonance imaging [MRI], not plain
radiographs) only when indicators of serious pathology present
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| Shoulder dislocation: practice guidelines recommend radiographs before and after reduction, but studies call into question
need for postreduction radiographs; factors that increase risk for fracture include age \>40 yr, first-time dislocation,
and blunt traumatic mechanism of injury (eg, fall or motor vehicle accident [MVA]); techniques currently used
for reduction (eg, external rotation or scapular manipulation) do not cause fracture; physicians good at determining position
of joint (obtain radiograph if uncertain); patients with recurrent dislocations can help determine position of joint
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| Other radiographs: skull—inadequate screening tool for injuries to brain; 50% of patients with operable injuries to brain
had no positive findings on radiograph of skull; sinus—plain radiographs have low sensitivity and specificity for sinusitis;
CT overly sensitive, resulting in high rate of false-positive findings; diagnosis based on clinical symptoms alone typically
sufficient; most patients with sinusitis improve, regardless of treatment; nasal—determining presence of deformity
often difficult; common practice includes repeated application of ice and follow-up within 1 wk; subsequent treatment
based on status of nose (ie, straight or crooked) after inflammation subsides; radiograph generally not necessary; rib
series—chest radiograph more important than rib series in patients with trauma to chest and tenderness over rib; treatment
for rib fractures nonspecific; radiograph unnecessary
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| COMMON PEDIATRIC POISONINGS —Richard S. Weisman, PharmD, Research Associate Professor of Pediatrics,
University of Miami, School of Medicine, and Director, Florida Poison Information Center, Miami
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| Toxic plant ingestion: case—boy, 18 mo of age, has no symptoms ≈5 min after ingesting Nerium oleander; toxicity—
cardiac glycoside (same family as digoxin) has delayed effects on sodium-potassium ATPase; signs and symptoms—
nausea and vomiting occur 4 to 8 hr after ingestion; hyperkalemia develops in acute phase; bradycardia and significant
toxicity may develop if patient not treated; antidote—digoxin Fab (large dose required because of low crossreactivity);
referral—send child to ED, even if symptoms not evident
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| Toxic solvent inhalation: case—boy, 16 yr of age, presents with inability to walk and loss of sensation in hands and
feet; history of inhaling K2r spot remover for purpose of intoxication; toxicity—product contains toluene and xylene;
inhalation can cause severe metabolic acidosis, high anion gap, and renal tubular acidosis; laboratory studies reveal severe
hypokalemia; treatment—correcting hypokalemia reverses neurologic and sensory deficits; patient referred for
substance abuse
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| Antibiotics: case—parent, confused about dosing (non-English speaker), gave son, 3 yr of age, 1 tablet azithromycin
q6h; symptoms—severe abdominal pain and mild diarrhea; treatment—child not at risk for Clostridium difficile colitis;
initiation of soft diet, with observation and monitoring; referral—admit child to hospital if symptoms do not begin
to resolve 6 to 8 hr after last dose
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| Gamma hydroxybutyric acid, “Blue Nitro”: case—woman, 18 yr of age, collapsed in nightclub after ingesting Blue
Nitro; when paramedics arrived, patient not breathing and had blood pressure (BP) of 60/30 mm Hg; patient intubated
in ED; toxicity—chemically related to γ-aminobutyric acid (GABA), compound acts as neuroinhibitor, typically causing
dramatic depression of central nervous system (CNS) and respiratory function; treatment—patients often regain
consciousnness upon intubation; risk for vomiting and aspiration; no other treatment needed in this case
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| Bleach: case—girl, 3 yr of age, crying after swallowing mouthful of household bleach; no vomiting, stridor, or difficulty
breathing; treatment—1 to 2 glasses of milk or water to dilute bleach; household bleach has pH of 8 to 9 (ie, low
risk for caustic injury); ≈50% of patients vomit, therefore child kept in upright position to avoid possible aspiration
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| Furniture polish: girl, 3 yr of age, coughing after swallowing half teaspoon of Old English furniture polish;
complications—child actually aspirated some polish (light mineral oil); mineral oil interferes with surfactant in lungs
and causes atelectasis (abnormalities seen on chest radiograph), 4 to 12 hr after exposure; treatment—child admitted
to pediatric intensive care unit (PICU), had difficult course for 2 to 3 days, but ultimately recovered
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| Vitamins: boy, 5 yr of age, fed 25 chewable multiple vitamins (without iron) to younger brother (3 yr of age); child has
upset stomach 2 hr after ingestion; toxicity—important that vitamins did not contain iron; toxic dose of elemental iron
≈15 mg/kg; pediatric vitamins that contain iron have 15 mg per tablet (ie, maximum dose to avoid toxicity, 1 tablet for
every kilogram of body weight)
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| Black widow spider: girl, 5 yr of age, develops severe abdominal pain ≈6 hr after being stung on arm by black widow
spider; physical examination in ED reveals rigid abdomen; toxicity—venom prevents release of calcium ions from sarcoplasmic
reticulum, often affecting area of phrenic nerve; severe abdominal pain, rigid abdomen, elevated white blood
cell (WBC) count, and fever often occur; examination—history important, because spider does not leave obvious mark
on skin; significant muscle weakness and depressed reflexes typically occur in affected extremity; giving 100 to 500 mg
intravenous (IV) calcium gluconate dramatically reverses effects for ≈15 min, ruling out other abdominal catastrophes;
treatment—benzodiazepine to relax muscles; low-dose opiate for pain, if necessary; effects dissipate in 8 to 12 hr
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Educational Objectives
| The goal of this activity is to review clinical decision rules for diagnostic imaging and provide information about presentations
and treatment of toxic ingestions. After hearing and assimilating this program, the clinician will be better able to:
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 | 1. Implement decision rules for imaging patients who present to the emergency department (ED) with possible fractures.
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| 2. Discuss use of chest radiographs as a diagnostic tool in the ED.
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| 3. Compare different imaging techniques for patients who present to the ED with abdominal pain.
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| 4. Identify risk factors for traumatic aortic rupture.
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| 5. Acutely manage pediatric patients with toxic ingestions.
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Discussed on This Program
Azithromycin [Zithromax]
Digoxin [Digitek, Lanoxicaps, Lanoxin]
Digoxin immune Fab (ovine) [Digibind, Digidote]
Suggested Reading
Browning JG, et al: Imaging infants with head injury: effect of a change in policy. Emerg Med J 22:33, 2005; Cotner
ES: Lateral chest radiographs for detecting pneumothorax in supine trauma patients. J Emerg Med 29:104, 2005; Dobson
JV, Webb SA: Life-threatening pediatric poisonings. J S C Med Assoc 100:327, 2004; Dominguez S, et al: Prevalence
of traumatic hip and pelvic fractures in patients with suspected hip fracture and negative initial standard
radiographs—a study of emergency department patients. Acad Emerg Med 12:366, 2005; Edmond M, et al: Clinical
factors predicting fractures associated with an anterior shoulder dislocation. Acad Emerg Med 11:853, 2004; Jenny JY,
et al: Should plain x-rays be routinely performed after blunt knee trauma? A prospective analysis. J Trauma 58:1179,
2005; Knopp R: Comparing NEXUS and Canadian C-Spine decision rules for determining the need for cervical spine
radiography. Ann Emerg Med 43:518, 2004; Krenzelok EP: Ipecac syrup-induced emesis: No evidence of benefit. Clin
Toxicol (Phila) 43:11, 2005; Lanning DA: Using quantitative methods to improve the diagnostic workup for abdominal
pain in children. J Pediatr Surg 40:949, 2005; Lea E, et al: Diagnostic evaluation of foreign body aspiration in children:
A prospective study. J Pediatr Surg 40:1122, 2005; Marzullo L: An update of N-acetylcysteine treatment for acute acetaminophen
toxicity in children. Curr Opin Pediatr 17:239, 2005; Michael JB, Sztajnkrycer MD: Deadly pediatric poisons:
nine common agents that kill at low doses. Emerg Med Clin North Am 22:1019, 2004; Moore BR, et al:
Performance of a decision rule for radiographs of pediatric knee injuries. J Emerg Med 28:257, 2005; O’Conor CE: Diagnosing
traumatic rupture of the thoracic aorta in the emergency department. Emerg Med J 21:414, 2004; Sachdeva
DK, Stadnyk JM: Are one or two dangerous? Opioid exposure in toddlers. J Emerg Med 29:77, 2005.
Faculty Disclosure
In adherence to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to disclose any significant financial
relationship with the manufacturer or provider of any commercial product or service discussed. For this issue, the
faculty reported nothing to disclose.
Dr. Hendey was recorded in San Francisco at Topics in Emergency Medicine, sponsored by University of California,
San Francisco, School of Medicine, and held October 27, 2004; Dr. Weisman was recorded in Bal Harbour, Florida at
Contemporary and Future Pediatrics, sponsored by University of Miami, School of Medicine, Department of Pediatrics
and Department of Dermatology and Cutaneous Surgery, and held January 29, 2005. The Audio-Digest Foundation
thanks the speakers and the sponsors for their cooperation in the production of this program.
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