Wilderness Medicine Flashcards
Air embolism typically happens when divers ___________.
hold their breath during ascent or rapidly ascends
When you ascend, the surrounding pressure decreases which causes gases to expand. A large enough expanse can cause air to pass into the large blood vessels. The air can embolize to any part of the body and (causing stroke, MI, and any other type of end-organ dysfunction).
Air embolism typically starts happening ________ after ascending.
10 minutes
A diver starts experiencing confusion at great depth. What’s the likely problem?
Nitrogen narcosis
This happens usually at depths greater than 100 ft
Air embolism typically starts happening ________ after ascending.
10 minutes
A diver starts experiencing confusion at great depth. What’s the likely problem?
Nitrogen narcosis
How do you treat nitrogen narcosis?
Ascent
Black widows typically cause what symptoms?
Abdominal pain
The neurotoxin causes GI muscle spasm.
If a person is hypothermic and pulseless, continue CPR until the core temp is ___________.
32° C or greater
If it is greater than this and they are still dead it is ok to stop CPR from a hypothermia standpoint.
Lightning strikes typically cause what physical exam findings?
Lichtenburg sign
TM ruptures
The main cause of death in hypothermia is ____________.
ventricular arrythmia
People generally start to become altered when core temp drops below what?
90 F
People generally lose all vitals when temperature drops below ____.
75 F
When is someone cold and dead?
- When an arrest happened before the hypothermia, such as a trauma that then led to hypothermia
- When chest is frozen to the point that chest cannot be compressed
- When there is an apparent other cause of death (such as massive trauma)!
You should consider ___________ in all hypothermic arrest patients.
ECMO
People with arrest from hypothermia typically do well on ECMO, even if there has been a long down time and gaps in CPR. There are many reports of hours of CPR that have full recovery.
Defibrillation typically works only above what core temperature?
30 C
In addition to the dead patients who are hypothermic, you should also consider ECMO in ________.
Patients who are altered, hypotensive, have ventricular arrhythmia, or have a core temp less than 28 F
You need to check what lab before sending a hypothermic patient to ECMO?
Potassium
Severe elevations (>12) suggest a poor prognosis.
The wounds from fire ant bites are called __________________.
sterile pustules
These look like bacterial abscesses but do not require antibiotics.
Describe fire ants.
They are small (1/8 - 3/8 of an inch long) and reddish brown in color. There are other types of ants in North Carolina that look like this, though, so it is tough to identify unless they’ve bitten you.
Why is it so important to probe the depth of bite wounds on the head (particularly in children)?
Innocuous-looking wounds can hide skull penetrations that can lead to brain abscesses.
Review the management of sea urchin, jellyfish, and man-of-war stings?
- First, if you are on scene make sure that you are removing the afflicted person from water. If they are in extreme pain and disoriented there is a risk of drowning.
- Second, rinse aggressively with water.
- Third, do a local block to numb the area.
- Fourth, remove the spines.
** Note: warm water baths have the best data suggesting pain control.
A diver experiences vertigo. What is the likely etiology?
Barotitis
Water pressure causes compression of the middle ear which can irritate the vestibular nerve if the Eustachian tube cannot relieve the pressure. Severe barotitis can lead to TM perforation.
Review the grading of frostbite.
There are two grading systems. The old style delineates four degrees of frostbite and the new style merely notes superficial or deep.
Old:
- 1st degree: erythema or blanching without blisters (epidermis only)
- 2nd degree: erythema w/ clear bullae (epidermis to dermis)
- 3rd degree: erythema w/ hemorrhagic bullae (epidermis to subcutaneous tissue)
- 4th degree: necrosis of digits (epidermis to bone, muscle, and tendons)
New:
- Superficial: first and second degree (i.e., erythema +/- clear bullae)
- Deep: third and fourth degree (i.e., hemorrhagic blisters or necrosis)
Brown recluses have what distinctive external feature?
A violin-shaped mark on their posterior cephalothorax
Envemonatioin by coral snakes produces what toxidrome?
Cholinergic
How should you rewarm frostbite?
Immersion bath until the tissue is pliable.
Review the six different types of poisonous snakes in NC.
- Copperheads
- Water moccasins (aka cottonmouths)
- Rattlesnakes (3 different kinds)
- Eastern coral snakes
Importantly, bites from eastern coral snakes can take up to _________ hours to appear.
12
Because of this, people with these bites warrant admission for observation.
Other than local necrosis, what can brown recluse venom cause?
Coagulopathy
Why does exhalation on ascent prevent arterial air embolus during diving?
During ascent, lung volume expands due to the drop in extrathoracic pressure. If a diver does not exhale on ascent, the expanded lung volume must escape through another means. In severe cases, air is compressed into the vascular system into emboli.
Air can embolize to become PEs, STEMIs, or CVAs.
Treat with 100% oxygen, supine positioning, and transfer to a hyperbaric chamber.
Divers should wait how long to fly after a dive?
12-24 hours
What does Centuroides exilicauda cause?
The Baja bark scorpion causes local paresthesia when the wound is tapped, opsoclonus, temperature reversal, and fasciculations.
Ingestion of Amanita phalloides can cause what?
ALI
What is the after drop phenomenon?
As you rewarm a hypothermic patient, the cold blood in the extremities returns to the core and can cause a drop in the temp as you rewarm. Just keep rewarming.
Why is chilled IV fluid not recommended in the treatment of heat stroke?
It has been shown to lead to arrhythmias
Evaporative cooling is preferred.
What are the treatments for HACE?
Rapid descent
If that isn’t possible, then steroids and oxygen.
Note: HACE has a poor prognosis. If left untreated it is almost universally fatal.
True or false: acetazolamide treats HAPE.
False
Acetazolamide prevents AMS but does not treat HACE or HAPE.
What are the four ways of heat loss?
Radiation: infrared electromagnetic waves emitted by the body
Conduction: heat transfer through direct contact with a solid object (like lying on cold tile)
Convection: heat transfer through fluids/gases (like to the cold air)
Evaporation: sweat and mucosal surfaces
Review sea urchin injury management.
Sea urchin spines release dye and venom, discoloring the tissue and causing severe pain. All spines should be removed, first with manual removal and then with shaving if concern persists that there is still spines. Be careful not to break the spines, because this releases more dye.
As with any joint-space puncture, take special care to ensure the joint is intact and clean.
In addition to the MSK symptoms (“the bends”), decompression sickness can also present with what?
Vertigo and confusion (“the staggers”)
What are the presenting signs of oxygen toxicity while diving?
Divers who use nitrox (oxygen-enriched tanks) are at risk of oxygen toxicity, particularly at greater depths. It presents with neurologic symptoms, which are different from nitrogen narcosis because they present with paresthesias, twitches, and seizures without intoxication. It can also cause pulmonary toxicity.
What temperature should you set water to when rewarming a frostbitten extremity?
37-39 C
Review the complications of lightning strikes.
Cardiac arrest (both VF and asystole): these patients often respond well to prolonged CPR because the arrest is purely electrical (i.e., their body is still healthy even when pulseless).
Anisocoria: transient, caused by dysautonomia
Paralysis: transient, usually caused by stunning
Lichtenberg sign: skin burn
Rhabdomyolsis: caused by heated bones
Burns
When should you not rewarm frostbite?
When there is a threat of refreezing
Warming and then freezing again is thought to lead to worse outcomes in frostbite, so don’t rewarm until you’re sure you are in a stable warm environment.
Why should you not rely on brainstem reflexes for prognostication in hypothermic patients?
At very cold temperatures you can lose brainstem reflexes, but it is not permanent.
What are the core temperatures for mild, moderate, and severe hypothermia?
35 (less than 35 but above 32): mild
32 (less than 32 but above 28): moderate
28 (less than 28): severe
Shivering typically stops below what core temperature?
28 (82.4 degrees F)
What are kissing burns in electrical injuries?
Flexural surfaces can arc and cause thermal burns
In electrical injuries, there can be three types of trauma. What are they?
Electrical: arrhythmia, rhabdomyolysis, compartment syndrome
Thermal: arcing burns
Blunt/penetrating: they can be flung into things or have debris flung into them
How hot can high-voltage arcing be?
35,000 degrees
Surface of the sun is 10,000 degrees.
What delayed injury can toddlers who chew wires get?
Labial artery re-bleed
Which is the more common cause of TM trauma in diving, ascent or descent barotrauma?
Descent
In descent barotrauma,
How does hemotympanum develop in diving?
Failure of the Eustachian tube to equalize the pressure between the water in the ear canal and the air in the middle ear. The pressure differential then causes rupture of blood vessels.
What species is Latrodectus?
Black Widow
What species is Loxosceles?
Brown Recluse
Other than ulcer, what can Brown Recluse bites cause?
Fever and hemolytic anemia
What is the most fatal primary blast injury?
Pulmonary barotrauma (pneumothorax)
The primary mechanism for death by Elapid is what?
Respiratory failure from temporary paralysis
This toxidrome mimics botulism. As such, anyone with a suspected Coral Snake bite should be observed with baseline NIF done. If they begin to get any respiratory symptoms then urgent intubation is warranted.
Chilblains and 1st degree frostbite are difficult to distinguish on exam. What historical feature can help?
Recent ambient temperature
Frostbite requires freezing temperatures (below 32 F). If it hasn’t been below this then frostbite is unlikely.
What are the chokes, bends, and staggers?
The three kinds of decompression sickness:
- Bends: arthralgias
- Chokes: cough and chest pain
- Staggers: vestibular sickness
True or false: patients who have been injured by low-voltage AC current (like household) who are asymptomatic do not require EKG or telemetry.
True
How do you manage scorpionfish stings?
Immerse in warm water
The scorpionfish injects toxin. While not deadly, it is extremely painful. Heat denatures the venom and treats pain, so if there is concern for this then immerse in warm water.
Which kind of animals (a category, not specific species) harbors rabies?
Mammals
There are no non-mammals that carry rabies.
Which toxic ingestion is accompanied by a peppery taste?
Scombroid (histamine fish toxicity)
Think of a fish wrapped in peppercorns symbolizing the heat-stable histamine.
True or false: the treatment for 2nd degree frostbite is dry rewarming.
False
Dry rewarming can damage frostbite. Wet rewarming is always the way to go.
True or false: the treatment for box jellyfish stings is acetic acid.
True
What is the maximum temp recommended for rewarming frostbite?
39 C
Why do you warm the core before extremities?
Rewarming a cold extremity can release potassium that can trigger VF in an irritable heart.
What is the primary mechanism of heat loss at temperatures above 32C?
Evaporation
Note, evaporation doesn’t work over 75% humidity.
Which pit viper has a different kind of toxin?
Mojave rattlesnakes have a neurotoxin
What household plant can cause irritation from calcium oxylate crystals?
Elephant ears
True or false: Lichtenberg sign is usually permanent.
False
Generally self resolves.
Which types of fish commonly cause histamine-like reactions?
Tuna and mackerel
Scombroid
What pathology classically follows a sensation of truncal squeezing after ascent from a dive?
Neurological decompression sickness
This is “the stumbles” – a neurological disorder of ascent.
How long after the first rabies vaccine can you give immune globulin?
7 days
What additional risk do nail injuries from pneumatic nail guns have?
Retained foreign body
The nails are held together with glue, paper, and sometimes wire. When they are shot into a hand they can push that material into the tissue.
Scorpions cannot climb _______________.
glass
To prevent bites in endemic areas, people sometimes put the legs of their beds in glass jars.
What is the dose of steroids for poison ivy?
50 mg daily for 21 days with subsequent taper
What envenomation causes paresthesias followed by flaccid paralysis?
Blue-ringed octopus
