Environmental Flashcards
Describe the classic presentation of heat-related illness.
Typically temperature exceeds 40C
Tachycardia
Commonly normotensive, but may be hypotensive
*Severe CNS dysfunction
Pupils may be fixed, dilated, pinpoint or normal
Nystagmus or oculogyric episodes may be present
Typically hyperdynamic cardiovascular state
Hypodynamic state signifies impending CV collapse
Tachypnea and hyperventilation
*GI hemorrhage occurs frequently
Jaundice and elevated liver enzymes occurs commonly
Fulminant hepatic failure and DIC rarely occur
*Muscle tenderness and cramping are common
*Rhabdomyolysis and ARF are common complications of EHS
Heatstroke is defined as hyperthermia usually greater than ___C associated with severe CNS dysfunction and anhidrosis (some pts maintain ability to sweat).
40
Mortality rate of heat stroke is over ___%.
70%
What are the 2 major types of heat stroke?
Classic vs. exertional
What is “classic heat stroke”?
- What pts is it more common in?
- What CNS sx can it cause?
- Typically occurs during environmental heat waves as a result of the body’s failure to dissipate heat. P/w hyperthermia and an altered sensorium that develops suddenly after prolonged exposure to elevations in ambient temperature.
- It is more common in the very young, the elderly, and the chronically and mentally ill.
- Variety of CNS sx including irritability, delusions, hallucinations, seizures or coma.
List some meds and conditions that impair the patient’s ability to tolerate heat stress.
Diuretics, antihypertensives, anticholinergics, and neuroleptics
Advanced age, hypotension, coagulopathy, and endotracheal intubation are poor prognostic indicators regardless of successful cooling measures.
What is “exertional heat stroke”? What pts is it more common in?
- What sx can it cause?
- Usually affects young healthy individuals who are unable to dispel heat due to endogenous heat production (Athletes and military recruits)
- These patients present with hyperthermia, diaphoresis, and an altered sensorium usually during extreme physical exercise in a hot, humid environment. Abdominal cramping, nausea, vomiting, myalgias, diarrhea, headache, dizziness, dyspnea, weakness, or syncope typically precede exertional heatstroke
What are risk factors that predispose individuals to heat related illness?
Obesity, poor physical fitness, precedent illness, and lack of acclimatization
- cocaine or amphetamines or prolonged seizure activity.
Are classic or exertional heat stroke pts more likely to have rhadomyolysis, acute renal failure, coagulopathy, lactic acidosis, and hypoglycemia as a result of the illness?
Exertional
Define heat cramps.
Heat Cramps are brief, intermittent, severe cramps in muscles fatigued by excessive exercise and occur at a time of rest. They are thought to be related to salt deficiency and usually occur in the first days of excessive work in a hot, humid environment.
Define heat edema.
Heat Edema is characterized by edema of the feet and ankles in unacclimatized individuals exposed to warm tropical or subtropical climates. It is thought to be the result of increased hydrostatic pressure and vasodilation resulting in vascular leak and edema.
Define prickly heat.
Prickly Heat is an acute inflammatory skin condition caused by blockage of the sweat glands and a secondary staph infection. It is initially manifested by pruritic vesicles in the clothed areas that extend producing deeper vesicles that are less pruritic.
What sx characterize heat exhaustion?
- Is the core temp high or normal usually?
- Do they have neuro sx?
- What is the immediate initial tx?
- Heat Exhaustion is characterized by vague malaise, fatigue, nausea, vomiting, weakness and headache in the setting of heat stress.
- The core temperature is frequently normal or just mildly elevated. The patient is frequently water depleted from inadequate hydration, but may be salt depleted from rehydration with hypotonic solutions.
- Patients with true heat exhaustion have normal mental status, but may be tachycardic.
- Clinically heat exhaustion and heatstroke may be incredibly difficult to differentiate and if the diagnosis is unclear, cooling should be immediately initiated.
Define heat syncope.
- Who should be warned to be cautious about this?
Heat Syncope is the temporary loss of consciousness caused by intravascular shunting to the cutaneous circulation, pooling in the lower extremities due to prolonged standing, and volume depletion. The elderly are particularly susceptible and should be warned to move often and avoid prolonged standing.
Consider 3 initial actions to take in a heat-related illness pt.
- Obtain fasting blood sugar in all patients with altered mental status
- Rapidly obtain rectal temperature
- Initiate rapid cooling simultaneously with any basic resuscitation measures
*Explain some labs/tests you might want to get with heat-related illness.
- Glucose (AMS)
- BMP: Hypernatremia (dehydration), hyponatremic (free water), Hypokalemia (early), hyperkalemia (muscle dmg), renal fcn tests (myoglobinuria)
- LFTs (hepatic failure)
- CK (muscle damage)
- CBC (thrombocytopenia, leukocytosis)
- BMP
- UA (hematuria)
- Chest X-ray (pulmonary infarction, edema or atelectasis)
- Head CT or LP (AMS)
- EKG (RBBB or prolonged QT, etc.)
Hematuria on the dip stick in the absence of RBC’s on microscopic exam suggests ______________.
Rhabdomyolysis
How is the dx of heat stroke or heat exhaustion made?
Clinical suspicion
- Caution: pt may have been cooled by EMS, so temp may be < 40C on arrival +/- anhidrosis
Discuss the tx of heat-related illness.
Basic resuscitative measures and immediate, aggressive *cooling measures
In resuscitation of heat-related illness, a __________________ should be placed in the rectum or esophagus to continuously monitor core temperature.
thermistor probe
In heat-related illness, the core temperature should be rapidly lowered to ___-___ C
38-39 C
Discuss ways you can cool a body in heat stroke.
Evaporative Techniques - Wetting body surface with continuous fanning External (Non-invasive) Conduction Techniques - Tap water immersion - Ice water immersion - Application of cold packs - Cooling blanket Internal (Invasive) Conduction Techniques - Gastric, peritoneal or bladder lavage - Cold IV fluids Pharmacologic Techniques - Dantrolene
What technique of cooling in heat stroke is no longer suggested?
- *Are antipyretics useful??
- Ice water submersion is extremely effective, but is now avoided since it may induce shivering which can generate increased heat and leads to vasoconstriction of cutaneous vasculature that reduces heat transfer.
- *Antipyretics ineffective and may exacerbate the hepatic, renal and coagulopathic abnormalities
While dantrolene use in heat stroke is controversial, explain how it works.
Dantrolene is a muscle relaxant that attenuates the amount of calcium released from the sarcoplastic reticulum in the skeletal muscles to the cytosol. Decreased intracellular calcium levels lead to reduced muscle metabolic activity and heat production.
- Not first-line, but can use if cooling methods fail
*In heat-related illness, what should you do if the pt is shivering?
Shivering leads to increased heat production and should be controlled with benzodiazepines
What type of shock is most similar to heat-stroke related CV collapse?
Septic
Rhabdomyolysis in heat stroke can cause renal failure.
- What is the major sign of AKI here?
- What is the tx?
- Dark tea colored urine and tender muscles are classic findings.
- Treatment includes infusion of large amount of IV fluids and alkalinization of the urine with IV bicarbonate infusion to prevent myoglobin precipitation in the renal tubules. Hemodialysis may be necessary for patients with ARF.
Hypothermia is defined as a core body temperature < ___C.
35C
In hypothermia, bystanders may report these changes about the patient.
a change in personality, paradoxical undressing (when cold), rocking, dysarthria, ataxia, or frank confusion.
What is trench foot?
Lower extremities with prolonged exposure to wet and cold conditions develop tissue damage, often presenting as paresthesias, pain, or numbness.
Describe some sx of mild (32-35C) hypothermia:
- *Tachypnea
- *tachycardia w/o HDS
- *Shivering
- Neuro sx: Dysarthria, ataxia, amnesia, altered judgment, apathy, fine and gross motor impairment: “Mumbles, grumbles, stumbles, fumbles, tumbles”
- *Polyuria
Describe some sx of moderate (28-32C) hypothermia:
- *Bradycardia
- *Bradypnea
- *Cessation of shivering
- Hypoventilation
- Arrhythmia
- Neuro: Paradoxical undressing, Decreased responsiveness, Hyporeflexia, Dilated and sluggish pupils, Dysarthria, ataxia
Describe some sx of severe (< 28C) hypothermia:
- Bradycardia
- *Hypotension
- *Pulselessness
- Bradypnea/apnea
- *Rigidity
- *Pulmonary edema
- *v-fib, *v CO
- *Coma/unresponsiveness, areflexia, fixed pupils
- *Oliguria
Describe frostbite on physical exam.
Tissues appear pale and firm, with poor capillary refill and sensation. Severe frostbite appears purple due to blood sludging.
Describe trench foot on physical exam.
Skin may appear red and swollen at first, progressing to blisters and bullae and finally hemorrhage in the skin and deeper tissues.
Describe the initial actions to take in a pt with hypothermia.
- Minimize jerky movement of the severely hypothermic patient as movement or exercise may precipitate v-fib
- Stabilize airway
- Stabilize breathing: administer warm humidified O2
- Stabilize circulation: monitor, ECG, warm IV fluids
- Remove cold wet clothing, dry patient, cover with warm dry coverings or warming blanket (bear hugger). Initiate active rewarming measures.
- Look for signs of accompanying cold injury, trauma, or underlying illness (secondary hypothermia)
The best method for measuring and monitoring core body temperature is a low-reading temperature probe in the___________ or ___________.
esophagus or rectum
In hypothermia, can you use a rectal thermometer?
No, rectal temperature probe (5 cm in, not in feces)
List some lab abnormalities seen in hypothermia.
Laboratory testing may reveal hemoconcentration, hypo/hyperkalemia, hypo/hyperglycemia, or abnormal coagulation. Tests that warm blood to 37C may give false positive or false negative results, e.g. arterial blood gas, coagulation studies.
What CXR finding might you see in severe hypothermia?
Pulmonary edema
What EKG changes might you see in hypothermia?
- J (Osborne) waves in moderate-severe cases
- prolonged intervals (PR, QRS, QT)
- arrhythmias (atrial or ventricular)
What rewarming techniques can you use for:
- Mild hypothermia
- Mod hypothermia
- Severe hypothermia
- Mild: Passive external rewarming
Blankets (remove cold wet clothes first)
Oral hydration with sugared drinks - Mod: Passive external rewarming + Active external rewarming
Electric or forced warm air blankets + often add noninvasive internal: warm IV fluids, warm humidified O2 - Severe: Active internal rewarming
warm IV fluids, warm humidified O2, warm bladder and gastric, or sometimes thoracic or peritoneal lavage (rarely done anymore) central arteriovenous or venovenous rewarming, cardiopulmonary bypass, dialysis
What medication should you give for bradycardia in hypothermia?
None, treat symptomatically
- Atropine ineffective
How does CPR protocol differ in a hypothermia pt?
Not at all, except that antiarrhythmics and repeat defibrillation should be deferred until the patient is warmed to above 30C.
- Administer bretylium if available.
*Review some complications of rewarming.
The patient’s temperature may decrease during rewarming (called afterdrop) as peripheral vessels dilate and increase return of cool blood from extremities to the core. Rewarming shock (hypotension) may occur as rewarming causes vasodilatation. Rewarming can also drop pH, electrolyte imbalances, and coagulopathy.
How is frost bite treated?
- Immediately immerse the affected area in warm water (37-39C).
- Remove constricting clothing and jewelry.
- Consult surgical services
- Treatment includes ibuprofen, tetanus toxoid, elevation, and analgesia.
- New: tPA to improve perfusion and decrease the incidence of amputation.
What is a potential complication of frost bite to watch for?
Compartment syndrome
What should you treat first, hypothermia or frost bite?
Hypothermia
What is the initial tx of trench foot?
Keep feet warm, clean, and dry.
Elevate the extremity.
Why do rewarmed hypothermic pts need to be observed?
For the development of DIC, rhabdomyolysis, pancreatitis, seizures, and other complications
True or false:
Providing aggressive rewarming and resuscitation efforts to patients in cardiac arrest due to hypothermia often leads to a full neurologic recovery.
True
The largest family of venomous snakes is ___________, which includes the subfamily of Crotalinae, or pit vipers.
Viperidae
- Rattlesnakes, copperheads, and cottonmouths are examples
Describe what viperidae look like.
- What is the most important characteristic that ID’s them?
- triangular head, elliptical pupils, fangs, and a characteristic ‘single row’ arrangement of their caudal plates.
- There may be a rattle
- The most important characteristic is the presence of bilateral “pits,” or heat-sensing organs, located between the eye and the nostril on each side
_________, the other venomous snake family besides viperidae, is comprised of cobras, and coral snakes, as well as many species of Australian snakes
Elapidae
How do you differentiate a harmless milk snake from a venomous Texas coral snake (elapidae)?
A Texas coral snake (“Red on yellow, kill a fellow”).
A harmless milk snake (“Red on black, venom lack” or “friend of Jack”)
What parts of the US have brown recluses?
South and Midwest
How do you ID brown recluses?
Referred to as ‘fiddleback spiders’ due to the dark fiddle (or violin) shaped marking on their dorsal aspect.
Most species of scorpians are not dangerous to humans, however, the __________ scorpion (C. exilicauda formerly sculpturatus) found in Arizona and New Mexico harbors a poisonous venom.
Bark scorpion
