TCP Week 7 (Environmental Emergencies)

mechanisms of heat loss picture

convection is air blowing off heat

mechanism of heat production/conservation

1. decreased blood and/or skin temp

2. impulses go to hypothalamus

3. vasoconstriction in skin blood cessels so less heat is lost to the environment

4. skeletal muscles are activated, causing shivering, which increases metabolism and generates heat

5. body temp increases

locations - core body temperature

- rectal

- bladder

- esophageal

hypothermia definition

core body temperature is less than 35 degrees Celsius (95 degrees Fahrenheit)

mild hypothermia temp

32-35°C (89.6-95°F)

moderate hypothermia temp

28-32°C (82.4-89.6°F)

severe hypothermia temp

< 28°C (< 82.4°F)

predisposing/risk factors for hypothermia:

- BGL?

- nutrition?

- alcohol?

- pituitary patho?

- DM?

- burns?

- Drug O.D.?

- aging?

- other?

- Hypoglycemia: decreased heat production

- Malnutrition: decreased heat production

- Alcohol abuse causes increase peripheral vasodilation --> increased heat loss

- Hypopituitarism: decreased BMR, decreased heat production

- DM impairs vasoconstriction --> increased heat loss

- Burns: increased heat loss via evaporation and radiation

- Drug overdose: impairs vasoconstriction increased heat loss

- Extreme age: decreased shivering, unable to produce heat

- Parkinson's disease

s/sx of mild hypothermia

- Shivering

- Ataxia

- Lethargy

- Dysarthria

- Pale, cold, numb skin early

- Increased BP, RR and PR

- Clouded sensorium/poor judgement

s/sx of moderate-severe hypothermia

- NO shivering

- Weak and or irregular pulse

- Slow shallow breathing

- Absent DTR's

- progressive decline in LOC

- Mild incoordination, confusion, lethargy, coma

effects of moderate-severe hypothermia on cardiac system

- Sinus bradycardia

- Slow atrial fibrillation, ventricular fibrillation, asystole

the heart is extremely irritable by rough handling or endotracheal intubation, so use caution

effects of moderate-severe hypothermia on EKG

- prolonged P wave and QRS intervals

- increased risk of V. fib or asystole

- T wave inversion

- Muscle tremor artifacts: fine baseline artifacts

- Osborne wave (J wave)

evaluation of hypothermia

- Identify the precipitant or risk factor(s)

- Thorough medical history

- Thorough physical examination

- Laboratory studies to evaluate for underlying disease

- ECG

- ABG

- Gentle handling to prevent arrhythmias

treatment of hypothermia

- Support the patient: ABC's

- Rewarm (but slowly!!)

why is it that rapid rewarming may be hazardous?

because hypothermic patients are particularly vulnerable to lethal cardiac arrhythmias

passive/external treatment for hypothermia

- move to heated shelter

- remove wet clothing

- layer with dry clothing and blankets

active/external treatment for hypothermia

- heated blankets

- warm packs

approx. ~105.8 F

active/internal treatment for hypothermia

- Large bore IV

- Heated IV fluids

- Heated, humidified oxygen

- Warm lavage of the bladder or stomach

- Peritoneal dialysis

- Open cardiac massage

severe hypothermia may appear clinically ________ yet...

may appear dead and yet respond to vigorous rewarming and resuscitation

therefore, a hypothermic patient should not be considered dead until all reasonable resuscitative measures have failed.

rewarmed to 36 degrees Celsius (96.8 degrees Fahrenheit); "no one is dead until they're warm and dead".

first degree frostbite

- Partial skin freezing

- Numbness, erythema, edema

- No blisters

- No tissue loss

second degree frostbite

- Edema, erythema and blister formation within 6-12 hours, blister fluid is clear

- Numbness

- No tissue loss

third degree frostbite

- Freezing with death of skin, hemorrhagic blisters

- Skin necrosis

- Blue-gray discoloration

fourth degree frostbite

- Freezing with full-thickness damage, with muscle, tendon and bone freezing

- Ultimate loss of body parts

- Eventually dry, black mummified

what comes first when treating frostbite?

treat hypothermia first; THEN thaw

thawing of frostbite

- remove wet clothing and apply dry clothing

- apply constant warmth, by exerting gentle pressure with a warm hand without rubbing

- separate digits

- elevate/protect from trauma

- no smoking

- gentle ROM

- rapid rewarming significantly decreases tissue necrosis --> immersion of the affected body part in 40-42 degrees Celsius water for 20-30 minutes or until flush

- parenteral opioid analgesics (i.e. morphine)

rapid rewarming is NOT ok with _______ but ok with _______?

do not rapidly rewarm with hypothermia

CAN use rapid rewarming with frostbite

post thaw of frostbite treatment

- rubbing a frostbitten extremity is a contraindication

- avoid refreezing

- debride clear blisters

- leave hemorrhagic blisters intact

- dress injured area and blisters with aloe vera cream

- tetanus immunization prophylaxis

- Ibuprofen 12 mg/kg per PO, divided doses

- IV fluids

- Antibiotics

- Begin daily hydrotherapy

- Surgery only if infection

hyperthermia

heat illness resulting in an imbalance between heating and cooling

predisposing factors to hyperthermia (elderly)

- poor physical condition

- possible cardiac pathology

predisposing factors to hyperthermia (young)

- decreased sweating

- increased metabolic rate

predisposing factors to hyperthermia (drugs)

- diuretics lead to depletion of Na+, K+, H20

- cocaine, hyperactivity

predisposing factors to hyperthermia (hazards)

hazards = firefighters

predisposing factors to hyperthermia (chronic dz)

- hyperthyroidism

- malnutrition

pathophysiology of heat edema

cutaneous vasodilatation and orthostatic pooling of interstitial fluid in gravity dependent edema

s/sx of heat edema

- Mild

- Pedal edema: elderly, lengthy sitting, non-acclimated.

- Temperature: normal

- BP: normal

- CNS: normal

- Sweat: +

- Heart rate: Normal

treatment of heat edema

- Elevate feet

- No diuretics (risk of electrolyte and water loss)

- Excellent outcome

pathophysiology of heat cramps

Sweat sodium losses may be replaced with hypotonic fluid resulting in whole body sodium deficit

excessive sweating → loss of sodium and water → replacing lost fluid with hypotonic fluids (pt drinks plain water) → sodium is not adequately replaced, becomes diluted → decreased extracellular sodium contributes to muscle cramps

s/sx of heat cramps

- Mild

- Painful muscle contractions

- Thirst

- Temperature: Normal or elevated

- Blood Pressure: Normal

- CNS: Normal

- Sweat: +

- Heart Rate: Tachycardia

treatment for heat cramps

- Move to a cool environment

- Rest

- Resolves after sodium balance is reestablished

heat exhaustion pathophysiology

- metabolic heat produced by muscles during activity outpaces body heat transfer to environment

- core temperature rises to levels that may disrupt organ function

s/sx of heat exhaustion

- syncope, N/V, confusion, decreased muscle coordination

- Temperature: Normal or up to 104F, 40C

- Blood Pressure: Orthostatic changes

- CNS: Usually normal

- Sweat: +, profuse

- Heart Rate: tachycardia

treatment for heat exhaustion

- Cool environment

- Rest

- IV saline

- Leg elevation

- Application of ice water soaked towels to the head, trunk, extremities

- Outcome: typically very good

pathophysiology of heat stroke

- Failure of thermoregulation.

- Internal organ tissue temperatures rise above critical levels .

- Children >> adults (higher metabolism)

s/sx of heat stroke

- Mental status changes; confusion, irritability, coma, seizures, ataxia

- Hyperventilation

- Temperature: > 104-105F (40-41C)

- Blood Pressure: normal

- CNS: Usually abnormal

- Sweat: (+) young and active; (-) elderly

- Heart Rate: Irregular

classical vs exertional heat stroke chart (know well)

treatment for heat stroke

- Immediate cooling to 38 C, (100.4 F)

- Fluid and electrolyte replacement

- Admit to ICU

- Poor Prognosis with delayed treatment (>2 hours) after onset

compare: heat stroke vs heat exhaustion

development of heat stroke

prickly heat

acute inflammation of the sweat ducts caused by blockage of the sweat pores by macerated stratum corneum

clinical features of prickly heat

pruritic, maculopapular, erythematous rash over the normally clothed areas of the body

treatment of prickly heat

- Wearing clean, light and loose fitting clothing

- Avoid sweat-generation situations

- Use of talc or baby powder is of no benefit

lightning (power)

- A single lightning bolt can release between 200 megajoules and 7 gigajoules of energy.

- This energy is enough to power a small town for a day

lightning (voltage)

- The voltage of a typical lightning flash is around 300 million volts.

- Some lightning bolts can reach up to 1 billion volts.

lightning (temperature)

- Lightning can heat the air it passes through to 50,000 degrees Fahrenheit (about 27,760 degrees Celsius).

- This is five times hotter than the surface of the sun.

"flashover phenomenon"

lightning often travels over the surface of the body called flashover and is less likely to cause internal cardiac injury or muscle necrosis

wet skin may decrease the risk of internal injury, helping the current travel along the outside of the body; this may explain how victims may survive exposure to tremendous amounts of electrical current

as the current passes over the skin, it vaporizes the moisture on the skin and may destroy clothing in an explosive manner and produced unusual skin burns

lightning burn (linear)

1st and 2nd degree burns

areas with heavy sweat

hand & neck with branching to chest and legs

lightning burn (punctuate)

full thickness circular burn with starburst pattern

lightning burn (feather)

caused by electrical current spread along the skin where resistance is low

the "burn" is a result of cutaneous imprints

from electron showers that track the skin and develop a fern like pattern with branches.

lightning burn (thermal)

2nd and 3rd degree burns from clothing and heated metal objects.

lightning strike management

- ABC

- ECG, cardiac isoenzymes, urinalysis, BUN and Creatinine, serum electrolyte

- Baseline hearing and vision

- IV Fluid replacement

- CAT scan r/o intracranial trauma

- Suspect hypothermia with thunderstorms

- tetanus immunization prophylaxis

- hospitalization

Hymenoptera Stings

local

-Swelling, erythema

-more extensive may have edema

-Risk varies with location: bronchospasm, laryngeal edema

-hypotension may occur with anaphylaxis

Hymenoptera Stings

toxic

multiple stings (>50)

-erythema, fever, HA, drowsiness, edema, involuntary muscle spasm, edema

-Risk varies with location: bronchospasm, laryngeal edema

Hymenoptera Stings - Management

-ABC (esp. with oral-facial swelling)

-Remove stinger, scrape instead of pinch/pull

-Ice, analgesics, antihistamine (i.e. diphenhydramine)

-Systemic reactions: epinephrine, IV fluid

-Corticosteroid

-Tetanus immunization prophylaxis

-Hospitalize patients with cardiovascular or respiratory comprise

Which is the Most Aggressive Wasp?

Yellow Jacket >> Cicada Killer

bed bugs

feed on blood in each stage of life (ew)

bed bugs clinical features

-Bites are typically painless

-Erythematous papules, bullae and wheals may develop

-Liner bite patter on skin is well described with bed bugs and brown or black patterns of excrement may be found on bed linen.

bed bugs treatement

Cold compresses, topical steroids, and antihistamine to relieve associated pruritus.

Symptoms following a bite: treat as previously outlined for Hymenoptera envenomation

Get rid of clutter, vacuum home, clean all fabrics, lightly spray insecticide onto all areas bed bugs are present, steam fabric and furniture, properly caulk all cracks and crevices will prevent bed bugs from finding their way back in the home.

Black Widow Spider - Pathophysiology of Envenomation

neurotoxic, causes depletion of acetylcholine from presynaptic terminal and end plate potentials at the neuromuscular junction, neurotoxin causes rigidity and spasms of most large muscle groups, especially the abdomen

Black Widow Spider - Clinical Presentation

initial? 15 min-1 hr? 2-12 hr?

Initially: "pinprick" sensation, fleabite appearance

15 minutes - 1 hour later: severe pain at the bite site, muscle spasm of the abdomen

2-12 hours later: CNS and PNS involvement, HA, diffuse paresthesia, muscle rigidity

• upper extremity bites: pain in chest

• lower extremity bites: pain in abdomen, may mimic pancreatitis, acute appendicitis

Black Widow Spider - Clinical Presentation

sx peak when?

Symptoms peak 2-3 hours after bite, last 24 hours-3 days, death is rare

Black Widow Spider - Management

-Generally symptomatic

-ABCs

-Symptoms usually reach max intensity in 1-3 hrs, can continue up to 48 hrs, low mortality rate

-IV calcium gluconate for alleviation of severe cramps associate with black widow spider bites

-Tetanus immunization prophylaxis

-Ice, wound care to bite site

Black Widow Spider - Management

high risk individuals

antivenom - one vial

test for horse serum sensitivity first, used if patient with black widow spider envenomation presents with abdominal pain, muscular cramping, irritability and hypertension

Brown Recluse Spider - Identification

Identified by a dark brown violin-shaped marking on its cephalothorax.

prefers warm, dry, untraveled areas (i.e. abandoned buildings, attics, closets, wood piles), fabrics (i.e. stored blankets, sheets and clothing) most bites occur in summer months, most bites occur at night (spider is nocturnal) or while dressing.

Identification:

-Brown to tan

-Both sexes equally dangerous

-Multiple bites suggest another cause

Brown Recluse Spider: Pathophysiology of envenomation

chiefly cytotoxic causing local tissue destruction and an intense inflammatory response

Brown Recluse Spider: Clinical Presentation

1-4 hours?

2-6 hours?

12-16 hours?

2-6 days?

Initially: +/- painful

1-4 hours later: Painful, red blisters at bite surrounded by pale ring, +/- red halo, Bull's eye lesion, Fever, chills, malaise, nausea

2-6 hours later: Serve burning pain, Pruritus

12-16 hours later: Wound site becomes vesiculated, Marked edema

2-6 days: Necrosis at bite site, Regional, lymphadenopathy , Shock

Brown Recluse Spider: Treatment

-Typical brown recluse spider bite self-limited and self-healing, without long-term consequences

-Pain resolves in about 1 week

-Lesions heal slowly

Treatment:

-Analgesia

-Close follow-up

-Antibiotics

-Ice, elevation

-Tetanus immunization prophylaxis

-Wound care