Acute Altitude Illness

ACUTE ALTITUDE ILLNESS

PATHOPHYSIOLOGY:

-Sense decreased arterial oxygenation –> increased ventilation –> respiratory alkalosis –> renal excretion of bicarb

-Maximum ventilatory acclimization after 4 to 7 days

-Increased erythropoietin

-Increased diuresis, hemoconcentration

-Decreased SV, Increased HR

-Pulmonary vasoconstriction

TREATMENT: OXYGEN, DESCEND (NOT necessarily to sea level, 3290 ft), hyperbaric bags, acetazolamide, dexamethasone (HACE), nifedipine (HAPE)

ACUTE HYPOXIA:

-Sudden and severe insult

-Symptoms: dizziness, dimmed vision, LOC

ACUTE MOUNTAIN SICKNESS (>7000 to 8000 ft):

-Headache, GI upset, dizziness, sleep disturbance, irritability, sleepiness

-Fluid retention and peripheral edema in contrast to diuresis of acclimatization

-Proportional to rate of ascent, especially sleep altitude

-NOT related to physical fitness

-2/2 hypobaric hypoxia

-If mild –> self limited

HIGH ALTITUDE PULMONARY EDEMA:

-Most lethal, recognize early!

-Sx:

EARLY: dry cough, DOE, rales, low for altitude Sa02%.

LATE: tachycardia, tachypnea, dyspnea at rest, weakness, productive cough, cyanosis –> then HACE

-Risks: heavy exertion, rapid ascent, excessive salt ingestion, use of sleep medication, h/o susceptibility, PULMONARY HYPERTENSION

-Hydrostatic edema, most often on second night

HIGH ALTITUDE CEREBRAL EDEMA:

–ATAXIA (most sensitive), AMS, stupor, coma

-Increased ICP, CN palsies

-Usually associated with pulmonary edema

OTHER CONSIDERATIONS:

-HYPOXEMIA MAXIMAL DURING SLEEP

-Don’t forget about associated injuries:

– hypothermia, frostbite, trauma, UV keratitis, dehydration, and lightning injury

-Ibuprofen as preventative measure?

-PAINS, 2012

-RCT trail in Annals of Emergency Medicine

-n=89, randomized to ibuprofen or placebo 6 hours prior to ascent

-43% developed symptoms in ibuprofen group vs 69% in placebo group

-Inflammatory response or masking headaches?

References:

Hackett PH, Hargrove J.Chapter 216. High-Altitude Medical Problems. In:Tintinalli JE, Stapczynski J, Ma O, Cline DM, Cydulka RK, Meckler GD, T. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7e. New York, NY: McGraw-Hill; 2011.http://accessmedicine.mhmedical.com.newproxy.downstate.edu/content.aspx?bookid=348&Sectionid=40381698. Accessed April 27, 2015.
Hill, Adam, et al. “Current Practice for Management of Acute Altitude Illness, Frostbite, and Snake Envenomation.” EM Practice Guidelines Update. Sep 2012, Vol 4, No 9.
Lipman et al. “Ibprofen prevents atlitude illness: a randomized controlled trial for prevention of altitude illness with nonsteroidal anti-inflammatories” Ann Emerg Med 2012 Jun; 59 (6) 484-90.
Rothwell, Seen. “High Altitude Illness.” Life in the Fast Last Lane. http://lifeinthefastlane.com/high-altitude-illness