On Wednesday I posted the latest in my “What Would You Do?” Wednesday posts, showing a climber on Aconcagua having a peculiar issue. The title of the video gave away what was going on, but its still a good mental exercise to think about patient management in this situation. If you haven’t had a chance to watch the video yet, take a few minutes and check it out!
This isn’t a hard scenario, and there isn’t all that much to catch. These guys are pretty high up there, with the altimeter showing 19,580 ft/5969 m. The speech disturbance (called aphasia) is pretty easy to catch; kudos to these guys for not only recognizing it, but being able to laugh at themselves.
HACE (High Altitude Cerebral Edema) is brain swelling caused by accumulation of fluid in the brain tissue. Patients typically present with symptoms very similar to acute mountain sickness (AMS), which causes including headache, fatigue, upset stomach, and dizziness. As more fluid accumulates, symptoms such as confusion, altered mental status, fever, difficulty speaking, and blurry vision develop.
HACE is easier to understand when you have a little background in the anatomy of the brain and skull. The skull is a rigid container which does a great job of protecting the brain. The skull is filled with brain tissue, blood, and cerebrospinal fluid (CSF). What the skull does not do so well is stretch; if more “stuff” enters the skull (such as fluid, in the case of HACE), since the volume of the skull cannot increase, pressure within the skull and on the brain increases. This pressure compresses brain tissue. When the areas of the brain that control speech and vision are compressed, vision and speech changes can result. If intracranial pressure (ICP) increases too much, it can begin to force the brainstem out of the skull through the foramen magnum, which is the big hole in the floor of the skull where the spinal cord connects to the brain. This is called herniation and it’s a major problem, because the brainstem controls heart rate/rhythm and breathing; pressure on the brainstem causes irregular breathing and slows the heart rate. Unconsciousness and death will occur if ICP is not relieved.
Interestingly enough, in many ways the HACE disease process is very similar to a hemorrhagic stroke. The major difference is that instead of being caused by the accumulation of blood in the brain from a punctured blood pressure, the fluid comes from extracellular fluid which leaks into the brain tissue, and is caused by hypoxia.
So, how are we going to manage this patient? In the spirit of full disclosure, I should say that I have never treated patients who are suffering from an altitude-related complaint. So, my treatment plan today comes from the Wilderness Medical Society Practice Guidelines for the Treatment of Acute Altitude Illness: 2014 Update.
An Ounce of Prevention: As with most things in wilderness medicine, preventing HACE is far better than treating it.
- Climb High, Sleep Low: It takes time to acclimatize, and HACE occurs more frequently in climbers who don’t take enough time to get used to the altitude and the oxygen concentration. Climbers should ascend slowly, with treatment guidelines stating “above an altitude of 3000 m, individuals should not increase the sleeping elevation by more than 500 m per day and should include a rest day (ie, no ascent to higher sleeping elevation) every 3 to 4 days. The increase in sleeping elevation should be less than 500 m for any given day of a trip.”
- Diamox: Using acetazolamide prophylactically (“as a prevention”) should be considered when climbing to altitude. Diamox causes deeper and faster breathing, which causes oxygen concentration to increase. Additionally, Diamox causes the body to excrete more fluid as urine, which helps decrease intracranial pressure. If using Diamox prophylactically, the dose is 125 mg twice a day.
- Decadron: Another medication used prophylactically to help reduce the chance of getting HACE is dexamethasone, a steroid. Decadron reduces swelling inflammation, which is good considering that we’re talking about swollen brains. The prophylactic dose is 2 mg every 12 hours, or 4 mg every 24 hours.
Treatment: When prevention fails and HACE develops, recognition followed by efficient treatment is necessary.
- Consider Differentials: What else could be causing the patient’s condition? Lots of things cause similar symptoms as HACE. If I didn’t know the patient in the video had HACE, I would have probably guessed he was either hypoglycemic (low blood sugar) or having a stroke. Take a few moments to rule out stroke, diabetic issues, and infection. We’ve talked about stroke symptoms in my post about altered mental status. If you’re able to test blood sugar, do it! You can do an effective exam to rule out other factors in a few moments, so you won’t be taking much time away from the patient.
- Descent: The most basic, most reliable, most effective way to treat HACE is to descend, and to do so as rapidly and efficiently as terrain, weather, and patient condition allow. Per the WMS treatment recommendations, “Individuals should descend until symptoms resolve, unless impossible because of terrain. Symptoms typically resolve after descent of 300 to 1000 m, but the required descent will vary between persons. Individuals should not descend alone, particularly in cases of HACE.”
- Gamov Bag: A Gamov bag is a portable hyperbaric chamber. The patient is placed inside, and the bag is inflated and pressurized, which simulates a lower altitude/higher barometric pressure. Gamov bags can temporarily stop or reverse altitude-related issues such as HACE. Be warned, however; Gamov bags are inflated by a foot pump and can puncture/burst, which makes them labor intensive and means they require constant attention. If your patient is claustrophobic or vomiting the Gamov bag will not be a fun place to be for them. Finally, remember that symptoms may re-develop when the patient is removed from the Gamov bag and “returned” to actual altitude.
- Oxygen: Patients with HACE will frequently also show signs and symptoms of hypoxia. Patients should be provided supplemental oxygen.
- Diamox: Diamox is a preventative agent for HACE. Once we’ve switched gears to treating HACE, WMS suggests a higher dose of 250 mg twice per day. Remember, diamox causes hyperventilation, which decreases ICP and increases blood oxygen levels, and also causes increased urination.
- Decadron: Your front-line medication for the treatment of HACE should be decadron, or dexamethasone. Per WMS, “Extensive clinical experience supports the use of dexamethasone in patients with HACE. It is administered as an 8-mg dose (IM, IV, or PO) followed by 4 mg every 6 hours until symptoms resolve.” Note that “PO” means “by mouth.”
I look forward to hearing from you! What are your thoughts? I’m particularly interested in hearing what the doctors in the room think, and what the experiences of those who have been to altitude, or have treated patients at altitude, are. Finally, have you had HACE? Care to write about it and tell us all what it was like? Let me know using the tag #wwydwednesday!
We’ll be back in a few days with more exciting airway information, and then another scenerio on Wednesday.