Environmental Flashcards
This deck covers Chapters 131-138 in Rosens, compromising all of environmental medicine.
What is Henry’s Law?
Henry’s Law
- ep = ekc
- Henry’s hovers
The amount of gas in solution is proportional to the pressure of the gas above the solution
Relevant in:
- DCS I/II
- Coca cola!
What are heat cramps? Name 4 professions at risk for this.
Cramps of most worked muscles after exertion
Copious sweating during exertion, then hypotonic replacement
Treat with salt solutions (Gatorade, IV NS)
At-risk professions:
- Athletes
- Roofers
- Steelworkers
- Coal miners
- Field workers
- Boiler operators
List 5 indications for active rewarming
- Cardiovascular instability
- Moderate hypothermia
- Failure of passive rewarming
- Endocrinologic insufficiency
- Trauma/Toxicologic vasodilation
- Secondary hypothermia impairing thermoregulation
* This is when illness sets a lower set temperature
* Opposite of fever, when higher set point set
List 10 factors that predispose you to HYPOTHERMIA
Decreased Heat Production
- Endocrine (DM, Hypothyroidism, Hypoglycemia)
- Inactivity
- Extremes of age (limited muscle to shiver)
Increased Heat Loss
- Environmental exposure
- Skin damage
- Ethanol (vasodilation)
- Iatrogenic (active cooling vs no blankets)
Impaired Thermogenesis
- Toxins (TCAs, SSRIs, Antipsychotics)
- CNS lesions
- Spinal cord injury
What changes are made in ACLS with hypothermic arrest?
- Pulse checks last 30 seconds
- Max 3 shocks until >30 degrees
- Avoid medications until >30 degrees
- Some give Epi x3 max
- Actively rewarm patient
- Continue CPR/Rewarming until 32 degrees
What is Dalton’s Law?
Dalton’s Law
- Ptotal = P1 + P2 + P3 + P…
- Dalton’s divides
The pressure in a mixture of gases is equal to the partial pressure of the proportion of gases in the mixture
Relevant in:
- Altitude medicine
- O2/N2 toxicity
List 10 risk factors for heat illness
Increased Heat Production
- Exercise
- Sympathomimetics
- Fever
- Delirium
- Hyperthyroidism
Decreased Heat Loss
- Drugs
- Skin disease
- Occlusive clothing
Impaired Heat Sensing
- Hypothalamus injury
- Atherosclerosis
- Diabetes
List tissues in the order of increasing resistance to electric current:
- Nerves
- Blood
- Mucous membranes
- Muscle
- Dry skin
- Tendon
- Fat
- Bone
What is Charle’s Law?
Charles’s Law
- V1/T1 = V2/T2
- Charles is Colder
At constant pressure, as volume increases, temperature increases.
Relevant in:
- Altitude medicine
How does High Altitude Pulmonary Edema (HAPE) present? Treated? Prevented?
High Altitude Pulmonary Edema
Symptoms
- SOB at rest, cyanosis
- Cough, Rales
- Tachypnea, Tachycardia
Treatment
- Mild - bed rest
- Moderate - oxygen
- Severe - descent/HBOT + Nifedipine 30mg q12h
- Consider sildenafil/tadalafil if can’t leave
- Consider Dex/Acetazolamide
Prevention
- Gradual ascent (500 m/day)
- Nifedipine 30 mg q12h
- Acetazolamide (Not evidence-based)
List two effects of temperature on ABG results
Sample warmed before analyzed in lab
Warming causes increased partial pressure of gases (Charles)
- Higher O2 than patient
- Higher CO2 than patient
What is malignant hyperthermia? How do you treat it?
Ryanodine receptor mutation
- Autosomal dominant
- Causes an uncontrolled increase in skeletal muscle metabolism
- Hypercatabolic
- Hyperthermic
- Tachypneic
- Tachycardia
- Rigidity
- Rhabdo
- HyperK
- Acidosis
Treatment
- Dantrolene 2.5 mg/kg
- 100% oxygen
- Cool
- Treat rhabdo, hyperK, acidosis
Define:
- Frostnip
- Frostbite
- Trench foot/Immersion Foot
- Chilblains
- Frostnip
- Superficial cooling injury without tissue loss
- Frostbite
- Cold injury with tissue loss
- Trench foot/Immersion Foot
- Cold injury from near freezing in wet environment
- Chilblains
- Cold injury from chronic dry cold
What are 6 factors that determine electrical burn severity?
- Type of Circuit (AC/DC)
- Duration
- Resistance of tissue
- Voltage
- Amperage
- Pathway
How much water do you need to aspirate to interfere with surfactant integrity?
How much water do you need to aspirate to cause intravascular abnormalities?
- Surfactant = 1-3 mL/kg
- Vascular = 11 mL/kg
How does the body physiologically adapt to altitude?
-
Hypoxic ventilatory response
* Medullar chemoreceptors sense lower PaO2 and stimulate hyperventilation. Resp alkalosis causes bicarb diuresis.
* Takes 1 week -
Cardiovascular
* Increased CO/HR/SVR -
Hematologic
* Increased EPO causes more RBC mass -
Increased 2,3-DPG
* Causes rightward shift in oxygenation curve
List 8 indications for prolonged telemetry in electrical injury
- Cardiac arrest
- ECG changes
- Arrhythmia
- LoC
- Chest pain
- Hx cardiac disease
- Cardiac risk factors
- Hypoxia
- Severe injuries
What is Pascal’s Law?
Pascal’s Law
- Delta P = pg(delta H)
- Pascal’s pushes (equally)
A pressure applied to any part of a liquid is transmitted equally throughout. Think tube of toothpaste.
Relevant in:
- Inner/Middle ear barotrauma
List 5 poor prognostic factors in drowning victims
- Hypoxia
- Age <3
- Submersion >5 min
- GCS 3
- Unreactive pupils
- Asystole
- Ongoing CPR
- CPR delay >10 min after rescue
- Severe acidosis
- Hypothermia
What is Joule’s Law?
Joule’s Law: P = VI
- P = Power (Watts)
- V = Potential (Volts)
- I = Current (Amps)
List 10 factors that predispose you to frostbite
Physiologic
- Acclimatization
- Dehydration
- Over-exertion
- Trauma
- Skin diseases
- Hypoxia
- Diaphoresis
Mechanical
- Wet clothing
- Immobility
- Inadequate insulation
Psychological
- Mental status
- Fear
- Attitude
- Fatigue
- Peer pressure
- Hunger
- Drugs/Alcohol
Environmental
- Temperature
- Humidity
- Wind Chill
- Duration of contact
- Altitude
Cardiovascular
- Hypotension
- Raynaud’s
- Anemia
- Sickle Cell
- Diabetes
List 4 diving disorders requiring HBOT
- DCS I
- DCS II
- AGE
- CO poisoning
List 5 mechanisms of heat loss
- Convection
- Conduction
- Radiation
- Evaporation
- Respiration
Name 5 indications to terminate resuscitation in hypothermic arrests.
- DNR
- Obvious death (other injuries, decapitated, etc.)
- Conditions unsafe (EMS)
- Temp >32 degrees + Asystole
- Avalanche burial >35 min
- K >12 mmol/L
What is the most effective method of cooling in the ED?
Tepid water fanning (Evaporative)
Ice water immersion
What is the earliest indicator of significant radiation exposure following whole-body radiation?
Vomiting within 1 hr
Lymphocytes <500 at 48h
List 5 mechanisms for lightning strike injury
- Ground current (50%)
- Side flash (30%)
- Upward streamer (10%)
- Direct strike (5%)
- Contact injury (5%)
- Blunt injury (unknown)
Outline the freezing injury cascade
Pre-freeze Phase
- Loss of sensation
- Increased blood viscosity
Freeze-Thaw Phase
- Intracellular dehydration
- Extracellular ice crystal formation
Vascular Stasis and Progressive Ischemia
- Microvascular thrombosis
- Tissue ischemia
Differentiate DCS from AGE
DCS
- Dependent on the dive profile
- Progressive onset
- Spinal symptoms
- Limb weakness
- Paresthesias
- Urinary retention
- Headache
AGE
- Independent of dive profile
- Caused by rapid ascent
- Rapid onset
- Cerebral symptoms
- Headache
- LOC
- Seizures
- Cardiac arrhythmia/arrest
Define:
- Drowning
- Submersion Victim
- Immersion syndrome
Drowning
- Respiratory impairment from submersion in liquid
Submersion Victim
- Submersion distress requiring transport to hospital
Immersion Syndrome
- Cardiac syncope after contact with water >5 degrees colder than you
What are the 2 types of heat exhaustion? How do you diagnose these? Treatment?
Types
- Water depletion (dehydration/hypovolemia)
- Salt depletion (hypotonic replacement of sweat)
Diagnosis
- NORMAL ALERTNESS (otherwise heatstroke)
- Fatigue, headache
- Tachycardia/Hypotension
- Rule out other illness (sepsis, etc.)
Treatment
- Rest, cool, IVF
What is the pathophysiology of DCS?
- Nitrogen bubbles form in blood during ascent
- Bubbles cause an inflammatory response
- Bubbles cause obstruction leading to ischemia/hypoxia
- Nitrogen is very fat-soluble = CNS vulnerable (myelin)
What is the minimum observation time for submersion victims?
List 4 discharge criteria that must be met.
6 hours
- Normal SpO2
- Normal CXR
- Normal ABG
- No symptoms
Outline a rewarming protocol to use in the ED for frostbite
Pre-thaw
- Assess pulses
- Avoid friction massage
- Stabilize core temperature
- Rehydrate
Thaw
- IV Ketorolac/Opiates PRN
- Advil 600 mg q6h
- Immerse in 37-39 degree water, gentle circles
Post-Thaw
- Dry and elevate
- Aspirate clear vesicles
- Leave hemorrhagic vesicles
- Consider tPA/Td/ABx
Compare/Contrast DCS I and DCS II
DCS I
- MSK/Skin/Lymphatics involved
- Periarticular pain in UE/LE (diagnostic if gone with BP cuff)
- Cutis marmorata (patchy cyanotic marbling of skin)
- Extremity edema from lymphatic obstruction
DCS II
- Any organ system involved
- Any of the above plus:
- Spinal Cord
- Patchy motor/sensory deficits
- Brain
- H/A, diplopia, inappropriate behavior
- Inner Ear
- Vertigo, Nystagmus, N/V
- Lung
- SOB, CP, cough
List 4 types of radiation and their degree of penetration
- Alpha particles - Epidermis
- Beta particles - 8 mm
- Gamma rays - deep
- Neutrons - deep
How does High Altitude Cerebral Edema (HACE) present? Treated? Prevented?
High Altitude Cerebral Edema
Symptoms
- Severe H/A, Ataxia, N/V, Seizures, Altered LOC
Treatment
- Immediate descent
- Dexamethasone
- HBOT
- Oxygen
- ICP management
Prevention
- Gradual ascent (500m/day)
- Acetazolamide
Differentiate the following:
- Middle ear barotrauma
- Inner ear barotrauma
- Alternobaric vertigo
Middle ear barotrauma
- Ear pain during DESCENT
- Slight transient vertigo
- Hearing loss (CONDUCTIVE)
- Unilateral facial paralysis
Inner ear barotrauma
- Ear pain during DESCENT
- Vertigo/Nausea
- Hearing loss (NEURAL)
- Nystagmus, Ataxia, Romberg +
Alternobaric vertigo
- Ear pain during ASCENT
- Nausea
- TM injury with transient hearing loss
- Nystagmus
What is ‘let go’ current for men/women/children? What current causes respiratory arrest from diaphragm tetany?
Let Go
- 9 mA = Men
- 7 mA = Women
- 4 mA = Children
Respiratory Arrest
- 20-50 mA
When do most cases of AGE become symptomatic?
Within 10 minutes of surfacing
What are three options for the internal decontamination of radioactive poisoning?
-
Chelating
* DTPA, Prussian blue, D-Penicillamine -
Blocking
* Potassium iodide -
Bronchopulmonary lavage
* For inhaled exposures
List 6 risk factors for drowning
- Age
- Male
- Black
- Alcohol
- Time (Weekends/Summer/Daytime)
- Seizure disorder
- Long QT
- Autism
List 5 types of electrical burn
- Direct contact
- Indirect contact
- Electrothermal heating
- Arc (most destructive)
- Flame
- Flash
Compare exertional and classic heat stroke
Exertional
- Usually younger, healthier people who exercised
- Diaphoresis
- Sicker
- Rhabdo, DIC, AKI, Lactic acidosis
Classic
- Older, sedentary, comorbid
- Anhidrosis
- Mild coagulatopathy, CK, oliguria, mild acidosis
What are the recommendations for flying after diving?
- <2h diving = wait 12 hours
- Multiple day/Unlimited diving = wait 24 hours
- Patients post-HBOT = wait 72 hours
List the signs/symptoms of mild/moderate/severe/profound hypothermia
Mild (32-35 degrees)
- Shivering
- Ataxia
Moderate (28-32 degrees)
- Less shivering
- Stupor
- Bradycardia/Hypotension
- Atrial fibrillation
Severe (20-28 degrees)
- VF
- Acidemia
- Severe hypotension/bradycardia
- No motor response or reflexes
Profound (<20 degrees)
- Flat EEG
- Asystole
- ~14 degrees is lowest survival
Define active vs passive rewarming.
Passive rewarming - providing insulation and changing the ambient temperature of the environment to preserve and encourage heat generation.
- Eg. blankets, increasing ambient temperature
Active rewarming - adding heat directly to the patient to increase the temperature of tissues.
- Eg. warmed oxygen, warm IVF, warm lavage, HD, ECMO
List 4 chronic conditions which are contraindicated to climb to altitude
- CHF
- COPD
- Pulmonary HTN
- Sickle cell
What is heat stroke?
- Exposure to heat stress
- Severe CNS dysfunction
- Temp usually >40 degrees
- LFTs markedly elevated
Give a DDx of three things depending on diving illness:
- On Descent?
- At Depth?
- On Ascent?
On Descent
- Middle ear barotrauma
- Inner ear barotrauma
- External ear barotrauma
- Facial barotrauma
- Sinus barotrauma
At Depth
- Nitrogen narcosis
- Oxygen toxicity
- CO poisoning
- Hypothermia
On Ascent
- DCS I
- DCS II
- AGE (Arterial gas embolism)
- ABV (Alternobaric vertigo)
- GI barotrauma
- Barodentalgia
- Pneumothorax
- Pneumomediastinum
- Pulmonary hemorrhage
List 6 risk factors for DCS and 3 for AGE.
DCS
- Fatigue
- Dehydration
- Fever
- Hypothermia
- Obesity
- Strenuous exercise
Obese people Exercise, which makes them fatigued, dehydrated, and febrile.
- Dive profile
- Diving at altitude
- Flying after diving
- PFO
- Smoking
- Alcohol
AGE
- COPD (less lung surface to absorb bubbles)
- Emphysema
- Mucus plugging
- PFO
What is Boyle’s Law?
Boyle’s Law
- P1V1 = P2V2
- Boyles get Bigger (under pressure)
At a constant temperature, as volume increases pressure decreases
Relevant in:
- Scuba diving
- Air transport
How does Acute Mountain Sickness (AMS) present? Treated? Prevented?
Acute Mountain Sickness
Symptoms
- Headache, nausea, fatigue, insomnia
- HACE if cerebellar symptoms
- HAPE if SOB at rest
Treatment
- Stop ascending
- Acetazolamide for moderate cases
- Dexamethasone for severe cases
- Symptomatic control for headache
Prevention
- Gradual ascent (500m/day)
- Avoid alcohol/smoking
- High carb diet
Name 3 extracorporeal rewarming methods
-
Venovenous circuit
* No oxygenation support
* 2-3 degrees/hour -
Hemodialysis
* Stabilizes electrolyte/toxicologic issues
* 2-3 degrees/hour -
Continuous AV rewarming circuit
* Femoral catheters
* No perfusionist needed
* 3-4 degrees/hour -
Cardiopulmonary bypass (ECMO)
* Full Circulatory/Oxygenation support
* Requires anticoagulation/perfusionist
* 9-10 degrees/hour
List 5 treatment priorities in managing heat stroke
- ABCs, MOVID
- Rapid cooling
- Fluids
- Benzos to stop shivering
- Urine alkalinization for rhabdo
- Avoid shocks until myocardium cooled, if possible
List 10 sequelae of frostbite
Pain
- Phantom pain
- Chronic pain
Sensation
- Hypesthesia
- Dysesthesia
- Paresthesia
- Anesthesia
- Cold intolerance
- Heat intolerance
Autonomic Dysfunction
- Raynaud’s syndrome
- Hyperhydrosis
MSK
- Atrophy
- Rhabdomyolysis
- Compartment syndrome
- Stricture
- Necrosis
- Amputation
Dermatologic
- Edema
- Lymphedema
- Chronic ulcers
- Cancer
- Hair/Nail deformities
Miscellaneous
- Core temperature after drop
- ATN
- Electrolyte abnormalities
- Gangrene
- Sepsis
Define mild, moderate, severe, and profound hypothermia
- Mild = 32-35 degrees
- Moderate = 28 -32 degrees
- Severe = 20-28 degrees
- Profound = <20 degrees
What is the General Gas Law?
General Gas Law
P1V1/T1 = P2V2/T2
Combination of Boyle’s and Charle’s Law
