Download MBBS (Bachelor of Medicine, Bachelor of Surgery) Important Topics Environmental Emergencies for MBBS 1st Year Important Topics, MBBS 2nd Year Important Topics, MBBS 3rd Year Important Topics & MBBS Final Year Important Topics.
Drowning Definitions
? Nonfatal drowning
?Process of drowning interrupted
? Fatal drowning
?Death from drowning
? Water rescue
?Submersion or immersion without
evidence of respiratory
impairment
? All other terms should be avoided
2
Epidemiology of Drowning
? One of top two leading causes of accidental
death in children
? 2/3 of deaths are age < 30
? Young children
? Teens and adults
?Inability to swim
?Seizures
?Surveil ance
?Alcohol
?Fencing and locks
?Associated trauma
?Pools, bathtubs
?Inability to swim
?Curiosity, play
?Exhaustion
?Scuba
3
Drowning Overview
? Mammalian diving reflex (sudden cold water
immersion)
?Bradycardia, apnea
?Shunting of blood to CNS
?Decreased metabolism
?Children > adults
? Shock is rare in drowning
?Rule out trauma
?C-spine precautions: Diving, multiple trauma, or
unknown circumstances
? Salt vs. fresh water: no effect on survival
4
Drowning Survival Factors
? Primary factor is duration of immersion
? Also
?Water temperature
?Age
?Diving reflex
?Associated trauma
?Associated dysbaric problems
?Bystander CPR
?Water contamination
Low core temperature
correlates with bad outcome
5
SCUBA Diving
Contraindications
? Asthma
? COPD
? Seizures
? Sinus and ear
disease
? Syncope
? Panic disorder
? Vertigo
? Poor training
6
Diving: Laws of Physics
"Fizzyology"
? Henry's Law: The amount of gas
dissolved in a liquid is proportional to
the partial pressure of the gas in
contact with the liquid
? Dalton's Law: Partial pressure of a
gas increases with increasing pressure
?Both above - Decompression
Sickness and Nitrogen Narcosis
? Boyle's Law: The volume of a gas
varies inversely with the pressure
?Squeeze Syndromes
and Barotrauma
7
Barotrauma from Diving
? Squeeze Syndromes
? Disorders of descent (Boyle's Law)
? Barotitis Media: "Ear squeeze"
?Pain from pressure on the TM, due to inability
to equalize pressure (blocked Eustachian tube)
? TM can rupture with severe vertigo, N&V
? Treatment: Nasal decongestants, maneuvers
to open Eustachian tube (Valsalva, et al.)
? Other squeeze syndromes: Sinus squeeze,
facemask squeeze, eye squeeze, suit
squeeze, lung squeeze
8
External / Inner Ear Barotrauma
? External ear barotrauma
?Due to blockage of external auditory canal by
cerumen or ear plugs
? Inner ear barotrauma
?Hemorrhage or rupture of the inner ear round
window with sensorineural hearing loss =
labyrinthine window rupture
?Severe vertigo, N/V, tinnitus, nystagmus, ataxia
?Referral to ENT
9
Pulmonary Barotrauma
Pulmonary Over Pressurization Syndrome
? Rapid uncontrol ed ascent (Boyle's Law)
?Dropped weight belt
?BC malfunction
?Panic and charge to the surface
? Expansion of unvented lung gases on ascent
results in a "burst lung"
?Must exhale on ascent to "vent" the expanded
gases
? Clinical presentation
?PTX, pneumomediastinum, pneumopericardium
?Hemothorax from injured lung
?Arterial gas embolism can occur
10
Pulmonary Barotrauma
? Arterial gas embolism or AGE (high morbidity
and mortality)
?Pulmonary overpressurization causes alveolar
gas to enter systemic circulation
?Air emboli in coronary, cerebral and retinal
arteries
?Sudden and dramatic symptoms often with
focal neuro findings
?Presents on surfacing or within 10 minutes
(unlike decompression sickness, which occurs
gradual y)
?ALOC is the rule and seizures are common
?Dive chamber "stat" for treatment
11
Nitrogen Narcosis
? A disorder at depth from breathing
compressed air which may result in drowning
? High concentrations of nitrogen are neurotoxic
? Symptoms
Dalton's Law
?Euphoria
depth = partial pressure
?Confusion
Henry's Law
?Disorientation
More gas dissolves with
?Poor judgment
higher pressure
?Diminished motor control
? Treatment is control ed ascent to decrease the
amount of dissolved nitrogen in the brain
12
Decompression Sickness
? A disorder of ascent (gas comes out of solution)
? At depth, increased amounts of nitrogen dissolve
in blood and tissues
? Ascending too quickly causes nitrogen bubbles to
form in blood and tissues
? A spectrum of il nesses depending on location and
severity
? Length and depth of dive are the primary
determinants of risk
? Obesity is a risk factor (nitrogen is lipid-soluble)
? Two categories: I and II (II more serious)
? Treatment: Recompression in a chamber
13
Type I Decompression Sickness
? Affects musculoskeletal, skin, lymphatics
? "The Bends" or "Caisson's Disease"
? Periarticular pain (especial y elbows and
shoulders) 70% of al cases
? Pruritus, erythema, skin marbling ("cutis
marmorata") from venous stasis
? Intravascular nitrogen bubbles
cause a wide variety
of presentations
14
Type II Decompression Sickness
? Central nervous system decompression sickness
?High CNS concentration of nitrogen
?Prickly sensations in the limbs
?Low back and abdominal pain
?Spinal DCS: Limb paresthesias, weakness
?Dermatome sensory distribution is common
?Incontinence, priapism
?Headache, diplopia, dysarthria, inappropriate
behavior
?LOC is rare (it is common in cerebral air
embolism)
?Symptoms develop gradually hours after
surfacing (unlike arterial gas embolism)
15
Type II Decompression Sickness
? DCS of the lungs = "The chokes"
? Decompression shock = Vasomotor DCS
? DCS involving cerebel um or inner ear =
"The staggers"
?Symptoms the same as inner ear barotrauma
?Cause: Gas bubbles in inner ear or cerebel um
All decompression syndromes develop slowly
16
Miscellaneous Ascent Disorders
? Alternobaric vertigo
?Occurs on ascent
?Caused by unequal middle ear pressures
?Transient vertigo, nausea
? Barodontalgia (squeeze and reverse squeeze)
?Air trapped in a dental cavity expands on
ascent, causing tooth pain
? Gastrointestinal barotrauma
?Serious problems are rare
?Eructation, flatulence, bloating, abdominal
cramps
?Avoid carbonated beverages and
gas-generating foods prior to diving
17
Diving Injuries
? Disorders of ascent
?Pulmonary over pressurization syndrome
?Air embolism - sudden
?Decompression il ness - gradual
? Disorders of descent
?Squeeze syndromes
?Nitrogen narcosis (at depth)
18
Hyperbaric Chamber
19
Recompression Therapy
? Recompression is the definitive treatment for
decompression sickness and arterial gas
embolism
? Have a low threshold for treatment of DCS
?Delayed onset of symptoms is common
?More subtle symptoms may develop after
treatment of major symptoms
?Minor symptoms may progress
?May recompress up to 14 days after symptom
onset
20
Recompression Therapy
? Risks associated with flying
?Commercial planes pressurized to 5,000-8,000'
?May exacerbate al symptoms of
decompression sickness
?May result in new symptoms of decompression
sickness for divers without any symptoms
initial y
?No flying for 3-7 days post-treatment of DCS-1
?No flying for 1 month post-treatment of DCS-2
21
Blast Injury Classification
? Type I: Pulse of pressure (barotrauma)
? Type II: Flying debris (penetrating trauma)
? Type III: Flying humans (deceleration impact)
? Type IV: Toxic gases, radiation, burns
Ear: TM rupture, ossicle disruption
Lung: Pneumothorax, air emboli
Top 4 organs
GI: Hol ow viscus rupture
Type I injuries
CNS: Concussion, air emboli
22
High-Altitude Illness (1)
? Pathophysiology of high altitude il ness
?Hypoxia-induced over perfusion and increased
hydrostatic pressure with capil ary leak
?Increased sympathetic activity
23
High-Altitude Illness (2)
? Manifestations
?Acute Mountain Sickness (AMS)
?High Altitude Cerebral Edema (HACE)
?High Altitude Retinopathy (HAR)
?High Altitude Pulmonary Edema (HAPE)
?High Altitude Flatulent Expulsion (HAFE)
? Factors influencing development
?Rate of ascent and final altitude
?Physiology, acclimation, hydration
?Sleeping at altitude (ventilation decreases)
24
High-Altitude Illness (3)
? Risk factors
?Prior history of altitude il ness
?Residence at an altitude below 900 meters
?Pre-existing cardiopulmonary conditions
?R to L cardiac shunts (listen for a heart murmur)
and intrapulmonary shunts
?Pre-existing pulmonary hypertension / mitral
stenosis
?Exertion (physical fitness is not protective)
?Women and age >50 have a lower incidence
25
Acute Mountain Sickness
? Common with rapid ascent to 8-10,000 feet
? Headache, nausea, fatigue, insomnia +/- GI sx
? Worse with drugs, alcohol, sedatives, and any
respiratory depressant
? Prophylaxis: Acetazolamide (carbonic anhydrase
inhibitor) ? actual mechanism unclear
?Renal bicarbonate diuresis and metabolic acidosis
?Increased respiratory drive
?Increased oxygenation since less sleep-related
hypoventilation
?Contraindicated in sulfa al ergy
?Causes paresthesias, and rarely, aplastic crisis
? Treatment: NSAIDs, steroids, oxygen, descent
26
High-Altitude Pulmonary Edema
(1)
? High-altitude pulmonary edema (HAPE)
?Responsible for most altitude-related deaths
?Most commonly on the second night at altitude
?Resting tachypnea and tachycardia
?Most patients also have mountain sickness
?Fever / rales / pink sputum / normal heart size
?Non-cardiogenic heart failure
?Severe hypoxemia and respiratory alkalosis
27
High-Altitude Pulmonary Edema
(2)
? Treatment of HAPE
?Improve oxygenation with supplemental oxygen
?If rapid reversal does not occur (failure to
increase oxygen saturation to above 90% within
five minutes) descent is mandatory
?Portable hyperbaric chamber is another option
?Noninvasive ventilation may help
?Nifedipine to treat pulmonary hypertension
?Inhaled beta-adrenergics for wheezing
?Dexamethasone is not helpful in HAPE (some
recent debate exists here)
28
High Altitude Cerebral Edema
? A severe form of acute mountain sickness
? Usual y associated with high altitude
pulmonary edema
? Increased ICP, cerebral edema
? Ataxia, vomiting, confusion, seizures, coma
? Treatment
?Descent (definitive treatment)
?Steroids, mannitol
?Hyperbaric chamber
(Gamow bag)
29
Non-Cardiogenic
Pulmonary Edema
? Environmental causes
?HAPE
?Thermal injury
?Drowning
? Other causes
?Toxins: ASA,
phenobarbital, CO,
opioids
?Strangulation
?Fat emboli, amniotic
fluid emboli
30
Hypothermia
Mechanisms of Heat Loss
? Radiation: Majority of heat loss
? Conduction: Increases 25-fold when wet
? Convection: Wind chil , rewarming
? Evaporation: Important heat loss mechanism in
hot environments
? Respiration: Smal but obligate contribution
31
Hypothermia Physiology (1)
? Hunter's response (CIVD)
?Cold causes vasoconstriction to preserve heat
?Then Cold Induced VasoDilatation
?Paradoxical undressing
? Cold-induced diuresis
?Distal col ecting tubule dysfunction
? Paradoxical core afterdrop (PCA)
?Warming vasodilates periphery
?Cold, lactate-rich blood returns to core
?Core pH and temperature drop
32
Hypothermia Physiology (2)
? Volume resuscitate with NS
? LR is poorly metabolized by cold liver
? Cold coagulopathy: All coag factors and
reactions are temperature-dependent
? Glucose: High if diabetic or CVA, low if
metabolized in attempt to keep warm
? Thermogenesis: Shivering thermogenesis is
lost at 26?C, leading to rapid decompensation
? Oxyhemoglobin curve shifts to the left,
increasing oxygen binding of hemoglobin
33
Hypothermia Definitions
? Definition: core temp < 35 oC
?32-35 oC: Adjustments to retain and generate
heat (shivering thermogenesis)
?<32 oC: Slowdown of body functions and
metabolism, decreased O2 utilization, CO2
production
? Risk factors: Extremes of age, altered
sensorium for any reason, burns, trauma
34
Hypothermia
Clinical effects
? Pulmonary: Increased risk for aspiration
? CNS: Altered mental status, incoordination,
confusion, lethargy, coma
? Renal: Cold diuresis and volume loss
? Vascular: Hyperviscosity, thrombosis, DIC
? Pancreatitis
? Bradycardia and slow A-fib with Osborn J
waves
? Myocardial irritability (epinephrine, dopamine and
atropine not indicated)
35
EKG Consistent With Hypothermia
?Bradycardia with an idioventricular or junctional escape rhythm
?Prominent J waves in the anterior leads
36
Osborn "J" Wave of Hypothermia
The name "J" wave is derived from the fact that the wave
begins at the "J" point of the ST segment
37
Hypothermic Cardiac Arrest
? Hypothermic arrest, core < 30 ?C: Aggressive
invasive rewarming measures (as indicated)
? PEA versus VFib
?Vfib, Vtach
?Bretylium (helpful if available)
?Amiodarone preferred to lidocaine
?Class III drugs which increase automaticity
? Single shock patterns better
? Only re-shock when core rises 1-2? C
38
Hypothermia
External Rewarming Techniques
? Passive external rewarming measures
?Remove wet clothes
?Cover with warm blanket
? Active external rewarming
?Hot water bottles to groin and axil ae
?Radiant heaters
?Bair hugger (blows hot air through
perforated blankets ? pictured)
? Potential problems with external rewarming:
paradoxical core afterdrop and acidosis
39
Hypothermia
Internal Rewarming Techniques
? Active core rewarming: Core temp < 30 ?C
or cardiac instability evident
?Warm humidified O2
?Warmed IV fluids
?Gastric, bladder, chest or peritoneal lavage
with warm NS
?Dialysis, extracorporeal bypass rewarming
? The patient is not dead until warm and dead
(core temp > 30 ?C) is false... truly dead
patients cannot be rewarmed
40
Frostbite
? Frostbite: Local tissue freezing (irreversible)
? Frostnip: Transient freezing (reversible)
? 1st degree: Superficial, erythema, no blisters
? 2nd degree: Ful thickness, edema, erythema,
clear blisters
? 3rd degree: Hemorrhagic blisters, skin necrosis
? 4th degree: Extension to bone
? Early clear blebs = GOOD
? Early hemorrhagic blebs = BAD
41
Frostbite
? Refreezing is VERY BAD
?Causes more damage than waiting
for evacuation and definitive treatment
? ED treatment
?Rapid rewarming: Circulating water (40 oC)
?Blister management
?Clear blisters should be debrided
?Hemorrhagic blisters should be left
alone
? "Frostbite in January - amputate in July"
?Conservative surgical debridement after
42
demarcation
Non-freezing Cold Injuries (1)
? Trench foot / immersion foot: prolonged wet feet
(urine)
?Mottled, anesthetic, pulseless foot
?Severe pain upon rewarming/reperfusion
?Hyperhidrosis and cold sensitivity are late findings
43
Non-freezing Cold Injuries (2)
? Chilblains: Painful inflammatory skin lesions
?Chronic intermittent exposure
to damp non-freezing temperatures
?Cutaneous symptoms 1-12 hours after
exposure
?Hands, ears, legs, feet
?Treatment: Rewarming, nifedipine, steroids
44
Heat-Related Illnesses
? Heat stress: Perceived discomfort and
physiologic strain associated with exposure to a
hot environment, especial y during physical work
? Heat exhaustion: Mild-to-moderate il ness due to
water or salt depletion that results from exposure
to high environmental heat or strenuous physical
exercise
?Thirst / weakness / anxiety / dizziness / faintness / H/A
?Core temperature may be subnormal, normal or
SLIGHTLY elevated (<40?C)
? Heat stroke: Hyperthermia associated with
systemic inflammatory response syndrome
(SIRS) and multi-organ dysfunction with
encephalopathy (altered mental status)
45
Heat Illness Spectrum
Severity
Name
Comments
Minor
Heat cramps Na+ losses (local)
(normal
Heat edema Elevation (not diuretics)
core temp) Heat syncope Vasodilation
Prickly heat
Blocked sweat gland
Moderate (slight Heat
N / V / D, water
core temp
exhaustion
depletion, salt depletion
elevation
Severe (core > Heat stroke
CNS dysfunction, liver "melt
40?C)
down", +/- anhidrosis
46
Heat Illness Factors
? Heart disease, beta blockers
(can't increase cardiac output)
? Anticholinergics, burns (can't sweat)
? Diuretics (can't sweat)
? Alcohol (can't sweat, impaired behavior)
? Hyperthyroidism (increased heat production)
? PCP, amphetamines, cocaine (increase heat
production)
? Obesity (insulation, poor skin blood flow)
47
Heat Stroke Types (1)
? Heat stroke mechanisms
?"Classic," nonexertional heat stroke
?Results from exposure to high temperature
and an inadequate physiologic response (e.g.
the elderly in Chicago heat waves)
?Exertional heat stroke
?Results from strenuous exertion (long
distance runners, military personnel, footbal
players, manual laborers, adrenergic abuse)
48
Heat Stroke Types (2)
? Classic
? Exertional
?Epidemic (with heat
?Isolated
wave)
?Exertional
?Nonexertional
?Healthy, active
?Elderly with chronic
?Profuse sweating
disease
?Anhidrosis
?DIC, ATN
?Rarely ATN,
?Rhabdo is common
rhabdomyolysis
?Diarrhea
49
Heat Stroke Features (1)
? Heat stroke manifestations
?Core temperature >40?C
?Tachycardia / hyperventilation / hypotension in
about 25%
?Respiratory alkalosis and lactic acidosis in
exertional heat stroke
?Manifestations of tissue destruction in those with
exertional heat stroke ? rhabdo, high K and PO4,
low calcium
?Multi-organ failure in severe cases ? shock,
ARDS, renal failure, etc.
?Altered mental status
50
Heat Stroke Features (2)
? Thermoregulatory system can't overcome heat
stress
? Body temperature >40 ?C
? Altered mental status
? Labs: Elevated LFTs (most sensitive), DIC,
increased CPK and myoglobin
Multi-organ failure + mental status changes
51
Heat Stroke Treatment (1)
? Two main objectives: Immediate cooling and
support of organ system function
?Cooling methods
?Conduction (increasing the temperature gradient
between the skin and the environment)
?Cold water immersion / ice slush / cooling blanket
?Evaporation (increasing the gradient of water vapor
pressure between the skin and the environment)
?Spray atomized cold water on the skin
?Convection via fanning (increasing the velocity of air
next to the skin)
?Radiation (do not cover the patient)
52
Heat Stroke Treatment (2)
? Evaporative cooling: Fans and water spray
? Ice packs to axil ae, groin and neck
? Adjunct only (not mainstay therapy)
? Immersion general y is not recommended
? Peritoneal lavage, gastric lavage, C-P bypass
? Chlorpromazine to interrupt shivering which
increases thermogenesis
? Correct electrolyte and acid-base disturbances
53
Burn Definitions
? 1st Degree
?Epidermis only (sunburn), no blisters
? 2nd Degree
?Dermis involved with blister formation
?Sensation intact
? 3rd Degree
?Ful thickness
?Anesthetic
?White or charred, waxy
?Eschar formation
? 4th Degree
?Muscle, fascia, bone
54
BSA & Resuscitation Formulas
? Rule of palms
? 1 Palm = 1% BSA
? Rule of nines for adults
? Lund-Browder chart for pediatrics
? Parkland (4), Consensus (3), or Brooke (2)
resuscitation formula .....
?4 mL x kg x % BSA per day of LR
?1/2 of volume over 1st 8 hours
? More if pulmonary or electrical components
? Galveston formula (using NS) for peds burns
? Fol ow urine output (>1 mL/kg/hr)
55
Rule of Nines / Adult
56
Lund-Browder chart / Infant
Front
18% Back
1%
57
ABA Admission Criteria
? Depend on practice setting, social parameters
? All 2? burns >10% BSA
? All 3? burns (unless extremely smal )
? All inhalation injuries
?Seared nasal hairs
VERY
?Sooty mouth
CONSERVATIVE
?Enclosed space
? All burns to face, ears, eyes, hands, feet, genitalia,
perineum, major joints
? Electrical burns
? Circumferential burns
? Co-morbid diseases likely to worsen progression
? Children <12 months of age
58
Second and Third Degree Burns
Med-Chal enger ? EM
Third Degree Burn
Med-Chal enger ? EM
Tar Burn to Hand
Tar Burn to Hand
Burn Complications
? Infection
?Pseudomonas (common)
?Other Gram negatives
? ARDS
?From shock state
?From direct pulmonary injury
? DIC from diffuse tissue injury
? Toxicity of smoke (CO, CN)
? Stress ulcers, GI bleeding
? Barotrauma (explosions)
63
Escharotomy
? Ful thickness circumferential limb burns
?Vascular insufficiency, poor pulses and
capillary refill
? Ful thickness chest wal burns
?Inadequate ventilatory motion
? Cut along long axis sides (avoid vasculature)
? Chest wal box
? Painless "pop" as sub-Q
tissues expand
? Minimal bleeding
64
Electrical Injuries (1)
? Tissue damage caused by electric current
? Traumatic injuries common (fal s)
? Electrocution: Death caused by electricity
? 3 high risk groups
?Toddlers: Household sockets, cords
?Adolescents: Risky behaviors, power lines
?Utility workers
? Many of the clinical effects related to amount,
duration, type (AC/DC) and path of current
65
Electrical Injuries (2)
? Voltage = Current x Resistance V=IR
Current more important than voltage
? Increased resistance produces increased heat
? Tissue resistance: nerve < blood < muscle < skin <
tendon < fat < bone
? Arc burns across flexor creases (kissing burns)
AC worse than DC
? AC: exit = entrance (held)
? DC: exit > entrance (thrown)
Oral commissure burns delayed labial artery bleed
66
Electrical Injuries (3)
? Injury depends on current and tissue resistance
? Increased injury severity with increased
resistance
?Bone, fat, and tendons heat up and coagulate
? Skin and neurovascular exam may underestimate
injury extent in deep tissue electrical burns
? Skin injury variable (wet, dry, salty)
? Fal s: Rule out other trauma
? Household electrical current: 60 Hz AC
? Maximum "let go" current: 30 mAmp
67
Electrical Injuries (4)
Low voltage injury: <1000 V
? More common, greater access, ? of al injuries
and deaths
? Burns tend to be minor (110 V)
? ? of low voltage deaths have no burns
? Low voltage AC causes cardiac arrest: Vfib
? Other arrhythmias rare with 110 V
68
Electrical Injuries (5)
? High voltage: >1000 V
?Significant injury and death >600 V
?US power lines 7620 V, lines entering house 220 V,
household sockets 110 V, 3rd rail subway 600 V
? High voltage injury
?Skin burns severe
?Violent skeletal muscle contraction, throw victim
?Fractures, dislocations (posterior shoulder)
?Clinical picture resembles crush injury
?High voltage AC/DC causes asystole cardiac arrest
?Dysrhythmias are common (PACs, PVCs, SVT, Afib)
69
Electrical Injury
Med-Chal enger ? EM
Electrical Injury
Oral commissure burn : 10% severe labial artery bleed,
usually after 5 days
?Recommend admission
?Out patient: reliable parents, can control blee Me
di d
n -C
g h a l enger ? EM
Lightning Injuries
? 2/3 present with lower extremity paralysis
? 2/3 have permanent sequelae
? Deep burns, extensive tissue damage, renal failure rare
(unlike electrical injury)
? Strike types: Direct (most serious), side flash, contact
strike (e.g. holding flag pole), ground current
? Massive DC electrical shock, brief duration, passes over
body, deep injury rare
? Ruptured TM (Type I blast injury)
? Motor paralysis
?Pupils unreliable (paralysis of the iris)
?Diaphragm paralysis
?Hypoxia
72
Lightning Effects
? Cardiac arrest
?Initial asystole sinus tach (automaticity)
?Diaphragm paralyzed longer than heart
?Respiratory arrest outlasts cardiac arrest
?Hypoxia Vfib
? Immediate cause of death: Apnea
? Early: CPR rather then cardioversion (AED)
? TM perforation and cataracts are common
? 50% of pregnancies have fetal demise
? Permanent cognitive and motor sequelae common
73
Lightning Injury
Punctate lesions due
to moisture/sweat
Med-Chal enger ? EM
Lightning Injury
Med-Chal enger ? EM
Radiation Exposure (1)
? Types of exposure
?External (e.g. radiation therapy)
?Internal (inhalation, ingestion)
?Contact with skin and clothes requires
decontamination
? Median lethal dose: 4.5 Gy
? Doses over 1 Gy produce GI symptoms (N/V/D)
? Survival probable <2 Gy
? N/V for 24-48 hours, then home
? Survival unlikely >8 Gy
? Fulminant N/V/D, desquamation
? Earlier symptoms indicate a higher dose and
worse prognosis
76
Radiation Exposure (2)
? Procedures and decontamination
?Evacuation (prevent new victims)
?Determine exposure type
?Early hospital notification
?Number of victims
?Decontaminate on scene if possible
?Separate hospital entrance
?Closed system drainage and ventilation
?Wash with soap and water (including hair)
?Trim nails, cut hair
77
Radiation Exposure (3)
? Rad = radiation absorbed dose
?Energy imparted to matter
? 100 rads = 1 Gray (Gy)
? Nonionizing visible light
microwave Heat
}
radar
? Ionizing - least penetrating
- 8 mm penetration (burns)
- deep penetration, acute
radiation sickness
? Neutrons: fal out
? Radon gas: decay of uranium 238 ()
78
Radiation Exposure (4)
? Tissues with high cel division are most affected
? GI & heme systems are the most vulnerable
? Suspect radiation il ness
?Unexplained burns, GI sx & pancytopenia
? Skin dosimetry and lab dosimetry (more accurate)
? Epilation ~ 3 Gy
? Erythema ~ 6 Gy
? Dry desquamation ~ 10 Gy
48 hour absolute lymphocyte count
(cel s most affected)
> 1200 (very good)
300-1200 (possibly lethal)
< 300 (lethal)
79
Radiation Exposure (5)
? Internal decontamination
?GI decontamination
? Activated charcoal and whole bowel irrigation
? Potassium iodide for I-131 ingestion
? Chelating agents for radioactive heavy
metals
? Supportive care
80
Biologic / Chemical Weapons
Biologic / Chemical Weapons
? Biological or chemical agents used with the
intent to kil , incapacitate, or cause fear
? Cheaper and easier to produce than nukes
? Mortality potential equal to that of nuclear
weapons
? Easily dispersed and difficult to detect
?Aerosolization (stationary or mobile sprayers)
?Contamination of food and water
?Person-to-person
82
Biologic / Chemical Weapons
? Characteristics that make bio-agents good weapons
?Infectivity, virulence, toxicity, incubation period,
transmission, lethality, stability
? Agents
?Bacterial: Anthrax, cholera, plague, tularemia,
Q fever
?Viral: Smal pox, Venezuelan equine encephalitis,
viral hemorrhagic fevers, hantavirus (cultivation is
difficult and expensive)
?Biological toxins: Botulinum toxin, ricin
83
Anthrax (1)
? "Woolsorter's disease" = Cutaneous form
? Three forms: Cutaneous, inhalational, GI
? Inhalation of spores, incubation 1-6 days
? Fever, chil s, drenching sweats, profound fatigue,
minimal y productive cough, nausea, vomiting,
chest discomfort sepsis and death (24 hours)
? Chest X-ray: Mediastinal widening, paratracheal
& hilar ful ness, pleural effusions, infiltrates
? Ciprofloxacin or doxycycline, vaccine
Exposed / infected patients
DO NOT require isolation
84
Inhalation Anthrax
www.CDC.gov
Anthrax (2)
? Cutaneous Anthrax
?Painless, no rash
?Pruritic papule resembling an insect bite
vesicle (sometimes hemorrhagic)
rupture and ulceration eschar
?Patients with cutaneous anthrax may have
fever, extensive edema and other systemic
signs
?Antibiotics may not alter course
? Prophylaxis: Ciprofloxacin or doxycycline
?8 weeks if exposure is confirmed
86
Cutaneous Anthrax
www.cdc.gov
Plague
? Yersinia pestis via a rode nt zoonosis (transmitted by
flea bites, contact and inhalation)
?Pneumonic plague: Incubation 2-3 days, inhalation
of aerosolized bacteria (resp. isolation required)
? Fever, cough, bloody sputum, shock, DIC, LFTs; Gram's
stain, culture, serology; streptomycin, doxycycline,
chloramphenicol, vaccine
?Bubonic plague: The most common form of plague
Infected flea bites a person, or materials
contaminated with Y. pestis enter through a break in
the skin
? Swol en, tender lymph nodes (buboes), fever, headache,
chil s. No spread from person to person
?Septicemic plague: Complication of above
88
Bubonic plague
www.cdc.gov
Pneumonic plague
Extensive lobar consolidation
Requires respiratory isolation
www.cdc.gov
Smallpox
? Smal pox (variola virus)
?Airborne transmission, highly infectious
?Even one case is a public health emergency
?Incubation 7-17 days, not contagious until rash
?All lesions progress at same time
? Vaccine: live virus (vaccinia). 1? protection fades
after 5 years, revaccination lasts 30+ years
?Post-exposure vaccine is effective up to 3 days
?Adverse reactions: Accidental implantation, 2?
infection, eczema vaccinatum, EM, generalized
vaccinia, progressive vaccinia, keratitis
91
Smallpox
www.cdc.gov
Smallpox (vaccinia) Vaccine
Adverse Reaction
Progressive vaccinia (vaccinia necrosum)
www.cdc.gov
Smallpox (vaccinia) Vaccine
Adverse Reaction
Auto-inoculation of eyelid with vaccinia virus
www.cdc.gov
Isolation Recommendations
? Isolation is not required for anthrax
? Plague
?Respiratory isolation (48 hours), sputum and
tissue testing, CXR
?Bubonic plague can disseminate if untreated, and
secondary pneumonic plague (contagious) can
develop
? Smal pox
?Strictly quarantined
?Exposure contacts require respiratory isolation
for 17 days
95
Biologic Toxins
? Aerosolized botulism: Toxin can be absorbed through
inhalation. It is relatively easy to produce, stable for
aerosolization, and highly lethal
?Binds to the preganglionic membrane of cholinergic
synapses and inhibits acetylcholine release
?Earliest complication involves the eyes (double vision).
Progresses to descending paralysis and respiratory
failure
?Unlike nerve agents, doesn't cause miosis or copious
respiratory secretions
? Ricin: Cytotoxin, castor bean mash, inhalation; airway
necrosis, fever, cough, sweating, hemorrhagic pulmonary
edema; ELISA; treatment is supportive
96
Chemical
Weapons
? Vesicants
? Nerve agents
? Cyanide
? Lung-damaging agents
? Riot control agents
?CN and CS (Tear gas)
?OC spray
97
Vessicants
? Cause blisters on dermis
? Mustard: Dangerous as a liquid or gas
?After entering the body through dermis or via
respiration, it reacts with water. The resulting
chemical causes large necrotic blisters on the
dermis and mucus membranes
? Phosgene: Pulmonary edema, not a true vessicant
?Skin blanch and wheal usual y without blisters
? Lewisite: Dangerous as a liquid or gas
?Unlike mustard, causes immediate pain
?Results in increased capil ary permeability which
leads to severe shock and end-organ damage
98
Chemical Weapons
Nerve Agents
? Developed in WW II
? Tabun (GA), Sarin (GB), Soman (GD), GF, VX
? VX is the most potent, sarin the most volatile
? Powerful inhibitors of acetylcholinesterase
(SLUDGE, kil er "B"s, paralysis, death)
? High risk of secondary contamination
? Self-protection, decontamination
? Treatment: Oxygen, atropine, 2-PAM
? Military Mark 1 auto injector kit (2 mg atropine
and 600 mg 2-PAM)
99
Mammalian Bites
? Dog bite
? Cat bite (and scratch)
?Lowest infection risk
?
?Moderate infection risk
Pasteurel a multocida
?
?
Pasteurel a multocida
Rx: Amoxicil in /
clavulanate
?Rx: Amoxicil in /
? Human bite
clavulanate
?Clenched fist
?Consider in genital
wounds
?Highest infection risk
?Eikenel a corrodens
?Rx: Amoxicil in /
clavulanate
100
Clenched Fist - Human Bite
18
Axillary Adenopathy of Cat Scratch Fever
?Begins as smal vesicle / macule at the site of the bite or scratch
?Regional lymphadenopathy draining the site of the injury
?Can be caused by dogs, cats, monkeys
?Etiology believed to be Bartonel a henselae
?Antibiotics usual y not indicated / usual y a self-limiting disease
?Avoid I & D or other trauma to nodes (fistulas tracks may result)
102
Rabies
? RNA virus infects CNS, 0-5 cases/year in the US
? Dogs are main vector worldwide
?
Rabies
Bats are main vector in US
Bat, raccoon, fox,
? Negri bodies in sacrificed brain
skunk
? Prodrome
?Excitement
No rabies
?Opisthotonus
Squirrel, rodent,
?Hydrophobia
rabbit
?Salivation, lacrimation, unsteady gait
? Virtual y always 100% fatal once symptomatic
? Post-exposure prophylaxis
?Active HDCV: 0 - 3 - 7 - 14 days (add a 28 day dose if
immunocompromised)
?Passive HRIG: 20 IU/kg
103
Snakes
Coral Snake
Red on Black, Venom
Lack
Red on Yel ow, Kil a
Fellow
104
Rattlesnake Bite
? Envenomation grades
?Local (minimal), moderate, severe
? Up to ? are dry bites
? Venom effects on humans
?Cel injury: Swel ing, ecchymosis, tissue
necrosis, pain
?Coagulation system: Increased prothrombin
time, INR, decreased platelets, decreased
fibrinogen level: DIC
?Systemic injury: Capil ary leak and myocardial
depression (may lead to shock)
105
Rattlesnake Bite
Management
? No tourniquets
?Constriction bands may decrease lymphatic
spread of venom
? Incision and suction not recommended
?Human oral flora contamination
?Risk of neurovascular injury
? Ooze at fang mark is a reliable sign of
envenomation
? Antivenom
106
Rattlesnake Bite
Antivenom
? Indications
?Progression of local injury
?Pain, swel ing, ecchymosis
?Evidence of coagulopathy
?Prolongation of PT or INR, low platelet count,
low fibrinogen level
?Systemic effects
?Hypotension, confusion, repeated nausea
and vomiting, fasciculations, paresthesias or
other venom effects remote from the bite site
107
Rattlesnake Bite
Antivenom
? 2 types
?Polyvalent crotalidae immune Fab (sheep),
trade name CroFab
?Antivenin (crotalidae) polyvalent whole antibody
(horse), commonly cal ed "Wyeth antivenin"
? Dose varies with bite and antivenin used
? Side effects
?Anaphylactic and anaphylactoid reactions
?Delayed al ergic reactions (serum sickness)
?Febrile response to immune complexes
108
Rattlesnake bite
Med-Chal enger ? EM
Rattlesnake bite
Med-Chal enger ? EM
Coral Snake Bite
? Family Epapidae
? Bites uncommon (less than 1% of venomous
snake bites in U.S.)
? Venom is neurotoxic
? Onset of symptoms may be delayed 10-12 hours
? Minimal local complaints
? Paresthesias, altered mental status, cranial
nerve dysfunction, respiratory failure
? Supportive care
? Antivenom if severe; often not available
Spiders
Black Widow (Lactrodectus) Brown Recluse (Loxoscelese)
Spiders
? Black Widow
? Brown Recluse
(Lactrodectus)
(Loxosceles)
?Red "hourglass"
?Dark "violin" top
?Outhouses, dumps, ?Woodpiles, cel ars
woodpiles
?
?
Immediate pain
Delayed pain
?Aggressive
?Reclusive
?N/V, cramps
?"Volcano" lesion
?Rigid abdomen
?Ischemic necrosis,
(mimics appy)
hemolysis
?Ice, opioids
?NO ice
?Ca gluconate +/-
?Dapsone, HBO,
?Antivenom
surgery
available
?No antivenom
113
Brown Recluse Spider Bite
Med-Chal enger ? EM
Brown Recluse Spider Bite
Logical Images Inc.
Brown Recluse Spider Bite
Bees, Wasps, Ants
? Acute Severe Systemic Reactions
(Anaphylaxis)
?IgE-mediated
?Cause of most bee sting deaths
?Usual y only 1-2 stings
?Occur 10-30 minutes after the sting
? Cardiovascular
? Respiratory
?Hypotension and shock
? Laryngeal
?Ischemia
edema
?Arrhythmias
? Bronchospasm
? Stridor
117
Bees, Wasps, Ants
? Systemic Toxicity
?Multi-organ complications
?DIC, renal failure, neurologic
?Response to large doses to venom
?Onset can be delayed 8-24 hours
?Mechanism not completely understood
?More likely if >50 stings (Africanized honey bees
or fire ants)
? Median lethal dose of honeybee venom
?19 stings per kilogram
?500-1,400 stings per human
118
Africanized Honey Bee Sting
Venom load causes systemic toxicity
Ticks
? RMSF
?Tick-transmitted Rickettsial infection
?Rumpel-Leede test (tourniquet produces
petechiae)
? Q Fever: Influenza-like il ness
? Tularemia: Rabbits
? Tick paralysis: Check hair
? Babesiosis: Hemolytic anemia
? Lyme disease: Ixodes tick transmits spirochete
? Borreliosis: Relapsing fever
? Ehrlichiosis: Monocytic, granulocytic
120
Tick
Med-Chal enger ? EM
Lyme Disease
Logical Images Inc.
Lyme Disease
Logical Images Inc.
Mosquitos
? Local hypersensitivity, severe local reactions, secondary
bacterial infection
? Diseases transmitted by mosquito vectors
?Japanese B encephalitis
?Yel ow fever
?Malaria
?West Nile virus
? A seasonal North American epidemic, from summer to fal with
manifestations ranging from asymptomatic (80%) to viral
encephalitis (1/150).
?Dengue hemorrhagic fever
? Viral infection in tropics and subtropics (Aedes mosquito);
acute, self-limited fever, myalgias, headache, rash,
lymphadenopathy, leukopenia
?Equine encephalitis
124
Marine Envenomations
? Jel yfish, box jel yfish, anemones, fire coral, and
Portuguese man-o-war
? Nematocyst: Spring-loaded stinging apparatus
injects venom; toxicity mechanism unclear
? Local reaction (erythema, pain, urticaria)
? Death is rare, box jellyfish
deadliest (respiratory arrest)
? Envenomation treatment
?No scrubbing; pick off tentacles
?Vinegar may help; hot water may help
?No fresh water
?Topical lidocaine may help
125
Marine Envenomations
? Coral cuts
?Prone to infection
?Some may contain stinging nematocysts (fire coral)
?Treatment: Soap and water; fresh water flush.
Vinegar if stinging. Antibiotics if appears infected.
Topical steroids, antihistamines if itching.
126
Marine Envenomations
? Sting Ray stings
?Barbed stinger apparatus
?Laceration, then envenomation
?Symptoms include local injury,
nausea, flushing, diarrhea,
diaphoresis, cramps
?Treatment
? Clean wound with water flush
? Debride
? Soak in water as hot as can be
tolerated (treats pain by
deactivating toxin)
? Antibiotics
? X-Ray for retained foreign body
127
Marine Infections
? Many pathogenic bacteria: Aeromonas,
Bacteroides, E. coli, Salmonel a, Staph, Vibrio,
Clostridium
?Vibrio (Gram negative rod, rapid infection)
?Pain, swel ing, hemorrhagic bul ae, vasculitis,
necrotizing fasciitis, sepsis
?Particularly problematic in alcoholics or
patients with liver disease
?Antibiotics: Ciprofloxacin, bactrim,
tetracycline
?Look for retained foreign bodies
128
Marine Infections
? Erysipelothrix (fish handler's disease)
?Painful, marginating plaques on hands
? Mycobacterium marinum (acid-fast bacil us)
?Chronic cutaneous granulomas
? Areomonas hydrophila: fresh water
?Cel ulitis and gastroenteritis
129
Ciguatera Toxicity
? Most common nonbacterial fish-borne poisoning
in U.S.
? From eating reef fish that consume
dinoflagel ates on coral reefs (amberjack,
groupers, etc)
? Ciguatoxin causes GI, cardiac and nervous
system symptoms (paradoxical temperature
reversal) and is heat-stable
? Treatment
?Antiemetics
?Cool showers, diphenhydramine for itiching
?Atropine for bradyarrhythmias
130
Scombroid Toxicity
? Mahi-mahi, amberjack, tuna
? Histamine-like reaction
? Toxin is not activated with cooking
? Toxin causes "al ergic reaction" ? flushing,
palpitations, abdominal pain, diarrhea; may see
wheezing, tachycardia
? Treatment
?Supportive
?Antihistamines
131
ENVIRONMENTAL
QUESTIONS
132
A SCUBA diver sees a blow fish and
panics, ascending quickly with his mouth
closed, expelling no air. What is the most
likely consequence of his breath holding?
A. "The bends"
B. Nitrogen narcosis
C. Pulmonary over pressurization syndrome
D. Decompression sickness type I
E. Arterial gas embolism
ENV 1
A 40 y/o commercial diver is evaluated for
decompression sickness. Which of the
following is true regarding this diagnosis?
A. Recompression is the treatment of choice
B. Delayed symptoms are uncommon
C. Minor symptoms do not progress
D. Cannot recompress more than 2 days after
the onset of symptoms
E. Recompression is frequently unnecessary
ENV 2
A 22 y/o triathlete flew from New Orleans
to the Rocky mountains to train. She
began experiencing headache and fatigue.
Regarding the medication she should be
treated with, which is true?
A. It causes a metabolic alkalosis resulting in
improved ventilation and oxygenation
B. It causes fluid retention thus improving blood
volume and perfusion
C. It is an effective analgesic
D. Although effective, its mechanism of action has
not been proven
E. It increases production of CSF
ENV 3
A patient presents with a reddened,
marbled look to the skin and pains in his
shoulders and elbows. He just landed
from a vacation in Cozumel. What activity
has caused his symptoms?
A. Eating fish
B. Deep sea fishing
C. SCUBA diving
D. Getting too much sun
E. Playing rugby
ENV 4
A patient presents following a simple,
itchy laceration from coral while diving.
Which regimen below is the most
appropriate treatment for this injury?
A. Decontamination, antihistamines and
topical steroids
B. Hot water and tetanus immunization
C. Prophylactic treatment for vibrio species
infection
D. Rinse with ? water ? isopropyl alcohol to
remove coral dust
E. Excision of wound edges
ENV 5
A 19 y/o swimmer is stung by a box
jellyfish. What is the usual cause of
death resulting from this injury?
A. Anaphylaxis
B. Respiratory arrest
C. Sepsis
D. DIC
E. Hyperkalemia
ENV 6
A 25 y/o patient received multiple venomous
hymenoptera stings. He is short of breath and
lightheaded. Which of the following is true,
regarding such stings?
A. Stings from "Africanized" honey bees are
more toxic than those from ordinary honey
bees
B. Most deaths are secondary to anaphylaxis from
one or two stings
C. Anaphylaxis from hymenoptera stings is IgM
mediated
D. The median lethal dose of honey bee venom is
10-20 stings
E. Systemic toxicity is less likely with Africanized
honey bees
ENV 7
A 35 y/o hunter was bit by a snake near a lake
in Georgia. He described the snake as
having red, yellow and black rings. Which of
the following is true regarding this snake?
A. It is a diamond back rattlesnake
B. It is a coral snake
C. Its nostrils sense heat of the victim to adjust
the size of the envenomation
D. It is a water moccasin
E. It is a member of the Crotalidae (pit viper)
family
ENV 8
A rattlesnake bites a 10 y/o boy on the
hand. Fifteen minutes later swelling, pain
and ecchymosis have developed. Which
statement is true, regarding this
envenomation?
A. Tourniquets are very helpful
B. Incision and suction are critical to the victim's
survival
C. Early antivenin therapy is indicated
D. Coagulopathy is a rare complication
E. Death is common from significant
envenomations
ENV 9
A 34 y/o firefighter presents after working an
active fire for 8 hours. He is diaphoretic and
has a rectal temp of 40.9. He is confused.
Which statement is most accurate, regarding
his heat illness?
A. This patient's presentation is consistent with
heat
exhaustion
B. Active cooling should be minimized to decrease
shivering
C. This patient's LFTs wil likely be elevated
D. Syncope is common with heat cramps
E. Rhabdomyolysis is not associated with this heat
il ness
ENV 10
A 40 y/o climber experiences headache,
nausea and fatigue at 11,000 feet. Which
of the following is true regarding this
illness?
A. Drugs and alcohol wil not exacerbate these
symptoms
B. Commonly seen with rapid descent
C. Acetazolamide (Diamox) may be helpful
D. The patient should immediately descend to
sea level
E. Rest and time for acclimatization are not
effective
ENV 11
48 hours after radiation exposure, a patient
has severe nausea and vomiting. His total
lymphocyte count equals 200. Which
statement is the most accurate, regarding his
prognosis?
A. The patient has had a lethal exposure
B. GI symptoms wil persist for a maximum of 72
hours
C. The patient wil recover with expectant
development of leukemia within 5 years
D. The patient wil have persistent immunological
problems
E. The patient wil recover without complications
fol owing chelation therapy
ENV 12
A 29 y/o patient was involved in a house fire.
He has extensive 3rd degree burns including
his chest and abdomen. His lungs are clear.
His blood gas confirms a respiratory
acidosis. Which is the most appropriate next
step?
A. Continuous albuterol aerosols
B. Intravenous solumedrol
C. Reduce his oxygen delivery as he is a CO
2
retainer
D. Box chest escharotomy
E. Sit the patient upright
ENV 13
A 30 y/o golfer is struck by lightning
and brought in for an evaluation.
Which of the following is associated
with this injury?
A. Examination of pupils may be unreliable
B. 50% mortality rate
C. Myoglobinuria is rare
D. Massive AC electrical shock
E. Cognitive deficits are transient
ENV 14
A firefighter was not using his SCBA while
putting out a house fire. He collapsed and
experienced respiratory arrest . Which
toxic gas is the most likely cause?
A. CO
B. CN
C. HS
D. CO2
E. H O
2
2
ENV 15
A child bites an electrical cord
sustaining an oral commissure burn.
Which is the most serious
complication?
A. Cataract formation
B. Delayed dysrhythmias
C. 7th cranial nerve palsy
D. Delayed bleeding 2o to labial artery
E. Facial cel ulitis
ENV 16
An adult patient weighing 70 kgs has
burns over both lower extremities. Which
is the best estimate of how much fluid the
patient should receive in the first eight
hours?
A. 630cc/hr = 5.0L
B. 275cc/hr = 2.2L
C. 950cc/hr = 7.6L
D. 500cc/hr = 4.0L
E. 1550cc/hr = 10L
ENV 17
A climber develops respiratory distress
and confusion after climbing to an
elevation of 15,000 ft. Examination
reveals rales in both lungs and ataxia.
The most appropriate treatment for this
patient is?
A. Immediate descent
B. Mannitol
C. Steroids
D. Nitroglycerin
E. Loop diuretics
ENV 18
A 36 y/o male is evaluated for severe
frostbite. Which of the following
actions should be taken?
A. Avoid early debridement of clear blisters
B. Refreeze the extremity if definitive care is
delayed
C. Rapid re-warming via 40oC immersion
D. Hemorrhagic blisters should be debrided
E. Avoid analgesics as they alter the
assessment
ENV 19
Why does passive external re-warming of
a hypothermic patient potentially result in
a worsened condition?
A. Vasodilation returns cold lactate rich blood to
the core circulation
B. The rate of re-warming is too fast
C. Rhabdomyolysis results from shivering
D. Vasodilatation results in rebound
hyperthermia
E. Ventricular fibril ation occurs most often with
passive external re-warming
ENV 20
Environmental Answer Key
1. C
11. C
2. A
12. A
3. D
13. D
4. C
14. A
5. A
15. B
6. B
16. D
7. B
17. A
8. B
18. A
9. C
19. C
10.C
20. A
This post was last modified on 24 July 2021