HAZARDS AND EMERGENCIES
From the annual Family Medicine Board Review Course, sponsored by the University of California, San Francisco,
School of Medicine
| OCCUPATIONAL AND ENVIRONMENTAL HAZARDS —Paul D. Blanc, MD, Professor of Medicine and Endowed
Chair, Occupational and Environmental Medicine, University of California, San Francisco, School of Medicine
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| Inhalational irritant exposure: eg, exposure to in situ production of chlorine gas by mixing sodium hypochlorite
(household bleach) with acid (eg, tile cleaner [dilute hydrochloric or phosphoric acid]); onset of symptoms immediate;
responses—mucous membrane irritation; burning eyes; runny nose; tracheobronchitis; hoarseness; cough; laryngospasm;
bronchospasm; pulmonary edema; adult respiratory distress syndrome (ARDS) with diffuse alveolar damage; high-solubility
materials (eg, sulfur dioxide)—cause rhinitis, mucous membrane irritation, and watery eyes; do not cause lung injury unless
exposure significant; low-solubility materials—may not cause watery eyes, but may cause lung injury that presents
12 hr later; with sufficient exposure, lung injury results, regardless of solubility; management—identify agent; obtain
work history; delineate immediate symptoms; if patient symptomatic, pulmonary function testing (PFT) or measuring peak
flow useful; bronchodilators as indicated; follow-up for resolution of symptoms; steroids useful in patients with sufficient
bronchospasm (no studies); persons with underlying airway disease more responsive
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| Febrile inhalational syndromes: metal fume fever—due to welding on galvanized metal; organic dust syndrome—
due to shoveling dust or mulch; marked by acute onset of febrile influenza-like illness for 24 hr; not associated with
acute lung injury; no specific testing needed; complete blood cell count shows elevated white blood cell count; tachyphylaxis
(patients may become asymptomatic with daily exposure; symptoms return with reexposure after hiatus)
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| Heavy metal pneumonitis: due to heavy exposure to toxic metals; cadmium exposure—occurs from flame-cutting
ductwork and other sheet metal; mercury fume—exposure from refining gold at home; acute lung injury syndrome; can
be fatal
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| Occupational asthma: common; can be due to synthetic low-molecular weight substances (eg, urethane) or high-molecular
weight substances (eg, animal dander); responses do not follow standard dose-response curve (once sensitized,
patients respond at low levels of exposure); management—identify low-molecular weight sensitizers; with high-molecular
weight substances, temporal association between new or worsening asthma and particular activity; initially, symptoms
may diminish with time away from particular activity, then asthma appears nonspecific (like idiopathic asthma);
testing includes portable peak flow monitoring at work and pre- and postexposure PFT; complete removal of (or from)
exposure
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| Chronic musculoskeletal disease: eg, chronic back pain, carpal tunnel syndrome, other entrapment neuropathies;
management—ask about repetitive motion, torque, and extension (of, eg, hands, wrists); perform physical examination
and nerve conduction testing; surgery not substitute for appropriate changes in work practices
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| Acute trauma: includes violence in workplace, motor vehicle injuries, and injuries from power tools, falls, and burns;
high-pressure injection injuries—occur from paint spray guns or high-pressure lubricating equipment; concerns include
amputation (due to severe local tissue injury from injection of materials); few physical findings initially (injury
evolves over 24-72 hr); acute surgical emergency (refer immediately); injury usually in nondominant hand; no specific
testing indicated
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| Occupational cancer: verify chronicity of exposure (single acute exposure unlikely to be associated with cancer risk);
delineate latency; no biomarkers used in routine clinical testing; occupation- or environment-related cancers not treated
differently from cancers of unknown etiology; may require referral to occupational medicine specialist
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| Cardiovascular disease: due to carbon monoxide; management—rule out use of combustion engine in closed space;
common with use of portable power generators and power equipment (including propane-powered equipment); methylene
chloride (common solvent in furniture strippers) metabolizes into carbon monoxide; check carbon monoxide levels;
assess technical industrial hygiene (difficult)
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| Reproductive toxicity: associated with exposure to heavy metals (particularly lead and organic mercury), hospital
chemicals, and pesticides (eg, dibromochloropropane [DBCP; banned soil fumigant]); management—focus on perceived
risks; no specific testing, except for heavy metals; temporary placement in lower-risk work situation
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| Neurotoxins: peripheral neuropathy—related to heavy metals, carbon disulfide, n-hexane (common component of
glues), and organophosphate pesticides; central nervous system (CNS) effects—manganese associated with parkinsonism;
management—obtain history of exposure (particularly skin contact); neuropsychiatric testing for CNS effects;
electromyography for peripheral neuropathy; removal from further exposure; be aware of other cases
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| Noise-induced hearing loss: preexisting hearing loss may worsen effects of ototoxic drugs; management—ask
whether work environment loud; audiometry (characteristic dip at 4 kHz); hearing protection; avoidance of superimposed
toxins
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| Dermatologic conditions: allergic and contact dermatitis; acute caustic injury; hydrofluoric acid exposure—severe
burn on initial presentation; few physical findings; exposure from working in microelectronics industry and using common
rust removal agents; delayed onset of severe local pain; high exposure can be associated with systemic hypocalcemia (treat
with calcium)
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| Psychologic disorders: posttraumatic stress disorder; mass psychogenic illness; invoked but not caused by chemical
toxic mechanisms; focus on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria;
refer for more detailed psychiatric evaluation if indicated
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| Hepatotoxins: chlorinated and nonchlorinated solvents; liver toxins with dose-dependent effects; hydrazine used in jet
and rocket fuels; illness usually in proximal association to exposure; often seen with change in job or job duties; exposure
through skin contact; alanine aminotransferase (ALT) to aspartate aminotransferase (AST) ratio should be >1; modify
work practices to remove overexposure
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| Renal disease: usually interstitial nephritis; caused by heavy metals; epidemiologic association between glomerular disease
and certain chemical hydrocarbon exposures; diagnosis challenging
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| Hematologic disorders: eg, methemoglobinemia in response to certain chemical exposures; bone marrow toxicity;
hemolysis; targeted history same as medication history; check methemoglobin levels
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| Systemic toxins: dinitrophenol used by some body builders; acute effect (directly upon exposure); identify recent exposure;
patients often seriously ill and not managed as outpatients
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| Other hazards and exposures: food contamination; community airborne releases; water pollution; indoor air or mold
contamination; difficult to link individual effects; control through public health interventions
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| Questions and answers: home methamphetamine laboratories (harm to firefighters and police officers)—skin contamination
less concerning than acute lung injury, due to adequate skin protection; concerns also for children whose families
producing methamphetamine; job-related stress and cardiovascular disease—epidemiologic association (direct cause
and effect); social insurance scheme in most states (eg, firefighters and police officers may receive workers’ compensation);
difficult to determine mechanism; exposure to mold—effects can include bronchospasm and allergic sensitization; neurologic
toxicity difficult to evaluate; mold control (eg, renovation) indicated; irritant-induced asthma—report occupational
illness and injury; consider convincing companies to perform small epidemiologic studies or investigations; asthma can become
permanent
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| MEDICAL EMERGENCIES —Michelle Lin, MD, Assistant Clinical Professor of Medicine, University of California, San
Francisco, School of Medicine, and Associate Residency Director, University of California, San Francisco–San Francisco
General Hospital Emergency Medicine Residency Program
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| Ventricular tachycardia: unstable—follow ventricular fibrillation algorithm; treat with epinephrine and 300 mg intravenous
(IV) amiodarone; stable—consider half-dose of IV amiodarone (ie, 150 mg)
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| Cocaine-induced chest pain: metoprolol contraindicated; management similar to that for acute coronary syndrome
(ACS), but β blockers may worsen hypertension and cause vasospasm and ischemic symptoms; use benzodiazepines instead
of morphine
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| Right-sided electrocardiography (ECG): indications include ST changes in II, III, and aVF leads (inferior leads);
right ventricle associated with inferior wall myocardial infarction (MI; mortality increases from 6% to 31% with concurrent
right ventricular [RV] infarction); RV infarction—patients highly sensitive to preload and nitroglycerin; give generous
fluids; use right precordial leads (V1 R through V6 R); ST elevation in V4 R 100% specific for RV infarction;
complications include hypotension, atrioventricular (AV) block, and right bundle-branch block; check right-sided leads
when evidence indicates inferior wall ischemia
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| Posterior ECG: to detect posterior MI, use posterior leads (V7 through V9 ); posterior MIs can be detected with regular
12-lead ECG initially (look for reciprocal changes in V1 through V3 ); look for ST depression in V1 and ST elevation in
posterior leads; tall R wave in V1 and V2 suggests Q wave on posterior lead; tall R waves can be caused by posterior MIs,
Wolff-Parkinson-White syndrome, right bundle-branch block, and RV hypertrophy; suspect posterior MI with tall upright
T waves in V1 and V2 ; flip and invert test (look at electrocardiograph through back side of paper, inverted)
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| Thrombolytics: indications for MI—give within 12 hr (contraindicated after 12 hr); 2 consecutive leads with ST elevation
>1 mm each, or new left bundle-branch block; indications for cerebrovascular accidents (CVAs)—onset of symptoms
within 3 hr; absence of blood or large ischemic CVA on head computed tomography (CT)
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| Pneumothorax: Pneumocystis jirovecii pneumonia most common cause in HIV patients; spontaneous
pneumothorax—1) primary; pristine normal lung parenchyma; 2) secondary; some underlying lung disease; traumatic
pneumothorax—from penetrating injury; tension pneumothorax—emergent; collapsed lung, tracheal shift, distended
neck veins, and hypotension seen on examination; treatment—1) small pneumothorax (<15%); give high-flow O2 (eg, 15
L of O2 by face mask over 24 hr); 2) tension pneumothorax; insert 14-gauge angiocatheter in second intercostal space; vent
high pressure; 3) “everything else in between”; tube thoracostomy with chest tube
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| Pericardial tamponade: causes Beck’s triad (uncommon; hypotension, distended neck veins, muffled heart sounds);
electrical alternans classic ECG finding; sinus tachycardia most common finding; treatment—large amount of IV fluids;
blind pericardiocentesis if patient decompensating; pericardial window if patient stable
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| Toxicology: atenolol—sinus bradycardia (usually first-degree AV block) classic ECG finding; lithium—main electrolyte
abnormality hypernatremia; causes nephrogenic diabetes insipidus; no ECG findings; digoxin—atrial P waves classic
ECG finding; every P wave does not have QRS complex; 75% of atrial tachycardia with variable AV block due to
digoxin toxicity; premature ventricular contractions most common rhythm of digoxin toxicity; symptoms include nausea,
vomiting, vision changes, and altered mental status in elderly; laboratory testing not helpful; hyperkalemia most common
electrolyte abnormality; give charcoal in acute stage and atropine for bradycardia; use sodium channel blocker (eg,
phenytoin or lidocaine for ventricular tachycardia); no role for dialysis; digoxin immune Fab (ovine; eg, Digibind) treatment
of choice; indications for Digibind include cardiovascular collapse, arrhythmias, hyperkalemia >6 mEq/L (do not
give calcium), altered mental status, digoxin level >10 mg/mL, ingestion (>10 mg in adults; >0.3 mg/kg in children);
phenobarbital and salicylates—increase clearance by alka-linizing urine; tricyclic antidepressants (TCAs)—treat by
alkalinizing serum and increasing protein affinity to free-floating TCAs; acetaminophen—treat toxicity with N-acetylcysteine;
rhabdomyolysis treated with urine alkalinization
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| Gastrointestinal decontamination: activated charcoal—first-line therapy; ineffective in binding lithium, alkali,
acids, heavy metals, inorganic minerals, quickly-absorbed alcohols, and hydrocarbons; ipecac not recommended; gastric
lavage—beneficial if performed within 30 min of ingestion; decontaminates stomach only; minimal benefit in outpatient
setting
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| Thyroid storm (thyrotoxicosis): aspirin contraindicated; patients present with CNS hyperactivity, tachycardia, diaphoresis,
fever, and significant weight loss; often fatal when left untreated; treatment—1) nonselective β blockers (eg,
propranolol) reduce tachycardia, palpitations, sweating, and fever; 2) propylthiouracil (PTU); blocks synthesis and conversion
of levorotatory thyroxine (T4 ) to triiodothyronine (T3 ); 3) iodine; high doses inhibit release of T4 from thyroid gland;
because of risk of causing short burst in hypothyroidism, give PTU 1 hr before iodine; 4) corticosteroids; theorized to
block conversion of T4 to T3 ; reduces mortality in thyroid storm
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| Diabetic ketoacidosis (DKA) and hyperosmolar nonketotic coma (HHNC): DKA—severe insulin deficiency
with production of stress hormones (eg, growth hormones); triglycerides become free fatty acids; ketone bodies
result in large anion gap acidosis; hyperglycemia and hyperkalemia in acute setting; HHNC—relative deficiency in insulin;
no production of stress hormones, free fatty acids, or ketone bodies; no acidosis; results in hyperglycemia and hyperkalemia;
signs of DKA—usually in type 1 diabetes; dehydration; nausea; vomiting; abdominal pain; tachypnea; signs of
HHNC—weakness and dizziness; weight loss; altered mental status in elderly; marked dehydration; causes include
stressors (eg, infection, acute MI); DKA often presents in patients with new-onset diabetes; medicine noncompliance can
cause DKA and HHNC; laboratory studies—higher glucose levels seen in HHNC with no acidosis; high osmolality
(>350 mOsm/kg H2 O); 9 to 10 L total body water deficit; electrolyte deficiency; treatment—fluids; electrolyte replacement;
insulin; decrease glucose by 100 mg/dL per hour
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| Severe allergic reactions: urticaria—well circumscribed skin plaques (wheals); treatment includes antihistamines,
H2 -blockers, and corticosteroids (for severe cases); angioedema—treatment same as for urticaria, and consider subcutaneous
(SQ) epinephrine for patients with impending airway occlusion; angiotensin-converting enzyme (ACE) inhibitors
can cause angioedema up to 5 yr after use; hereditary angioedema treated with fresh frozen plasma; anaphylaxis—severe
allergic reaction with systemic shock; treatment same as for urticaria, and SQ epinephrine for hypotension and laryngeal
edema; follow advanced cardiac life support (ACLS) resuscitation protocol
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| Head injuries: subarachnoid hemorrhage—most common cause of traumatic intracranial bleeding; acute blood appears
white on CT; arteriovenous malformation (aneurysmal bleeding) most common cause in absence of trauma; subdural
hemorrhage—caused by tearing of bridging veins; elderly people, patients with significant cerebral atrophy, and
long-term alcohol users at risk; epidural hemorrhage—neurosurgical emergency; appears as football-shaped, biconvex
hyperdensity; usually caused by arterial bleeding at middle meningeal artery; 80% of cases associated with fracture
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| Burns: total body surface area (TBSA) burned—“rule of nines” applicable to adults only; head, 9%; chest, 18%; back,
18%; each leg, 18%; each arm, 9%; perineum, 1%; in pediatrics, use Lund-Browder body diagram; patient’s palm can be
used to estimate 1% TBSA (independent of age); indications for admission to burn unit—if 10 to 50 yr of age and
TBSA burned ≥20% (second- and third-degree burns); if <10 yr of age or >50 yr of age and TBSA burned >10%; involvement
of perineum, genitalia, face, hands, feet, and/or joints; concerns about child abuse; electrical burns; chemical
burns with significant impairment; significant inhalational injury; comorbidity (eg, severe diabetes); carbon monoxide
poisoning more common in enclosed spaces (check carboxyhemoglobin level); look for singed nasal hair, carbonaceous
sputum, and facial burns; no indications for antibiotics in acute burns; be aggressive with fluid resuscitation
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Suggested Reading
Bowler RM et al: Sequelae of fume exposure in confined space welding: a neurological and neuropsychological case
series. Neurotoxicology 28:298, 2007; Chiasson JL et al: Diagnosis and treatment of diabetic ketoacidosis and the hyperglycemic
hyperosmolar state. CMAJ 168:859, 2003; Hampson NB et al: Carbon monoxide poisoning: a new incidence
for an old disease. Undersea Hyperb Med 34:163, 2007; Heard K: The changing indications of gastrointestinal
decontamination in poisonings. Clin Lab Med 26:1, 2006; Hennessey JV: Diagnosis and management of thyrotoxicosis.
Am Fam Physician 54:1315, 1996; Hogan CJ et al: High-pressure injection injuries to the upper extremity: a review of
the literature. J Orthop Trauma 20:503, 2006; Iqbal AA et al: Hypercalcemia in hyperthyroidism: patterns of serum calcium,
parathyroid hormone, and 1,25-dihydroxyvitamin D3 levels during management of thyrotoxicosis. Endocr Pract
9:517, 2003; Kogevinas M et al: Exposure to substances in the workplace and new-onset asthma: an international prospective
population-based study (ECRHS-II). Lancet 370:336, 2007; Latham L: Diabetic emergencies. Nurs Stand
19:64, 2005; Lindbohm ML: Effects of parental exposure to solvents on pregnancy outcome. J Occup Environ Med
37:908, 1995; Logeart D et al: ST-segment elevation in precordial leads: anterior or right ventricular myocardial infarction?
Chest 119:290, 2001; Nadon L et al: Cancer risk due to occupational exposure to polycyclic aromatic hydrocarbons.
Am J Ind Med 28:303, 1995; Thacker D et al: Digoxin toxicity. Clin Pediatr (Phila) 46:276, 2007;
Vaideeswar P et al: Isolated right ventricular infarction. Indian J Pathol Microbiol 43:277, 2000; Weiss SM et al:
Acute inhalation injury. Clin Chest Med 15:103, 1994.
Educational Objectives
| The goals of this program are to improve the management of occupational and environmental hazards and medical emergencies.
After hearing and assimilating this program, the participant will be better able to:
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 | 1. Identify signs of exposure to inhalational irritants.
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| 2. Predict toxic effects of certain irritants, such as carbon monoxide.
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| 3. Identify effective therapy in medical emergencies, such as cocaine-induced chest pain and digoxin toxicity.
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| 4. Select appropriate therapy for thyroid storm.
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| 5. Distinguish diabetic ketoacidosis from hyperosmolar nonketotic coma.
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Faculty Disclosure
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty members to disclose relevant
financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts
were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial
interest. For this program, the faculty reported nothing to disclose.
Acknowledgements
Drs. Blanc and Lin spoke in San Francisco, CA, at Family Medicine Board Review Course, presented July 9-12, 2007, by
the University of California, San Francisco, School of Medicine. The Audio-Digest Foundation thanks the speakers and the
sponsor for their cooperation in the production of this program.
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