EBC Day 11 – Everest Base Camp

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Altitude Sickness

That morning, a sad farewell took place in Lobouche (elevation : 4940m) amongst a group of hikers from New Zealand. One of the party members apparently had been suffering from a bad headache and had just begun mumbling unintelligibly. It was (wisely) decided that he would need to make a quick descent back down to lower altitudes, whilst the rest of the party continued up to Gorak Chep (elevation : 5164m). I say wise because the altered mental status (a.k.a AMS) indicated an onset of HACE.

As one ascends to higher altitudes, the saturation of the atmospheric gases decreases, which results in mild hypoxia--a deficiency in the amount of oxygen that reaches the body tissues. One's breathing and heart rate are then forced to increase in order to combat this hypoxia. The capillaries in the body also dilate, and the capillary leakage causes swelling (edema). Without sufficient acclimatisation, the signs and symptoms that one might encounter are:

Gastrointestinal issues: Loss of appetite, nausea or vomiting

Nervous system issues: Fatigue or lassitude, headaches, dizziness, difficulty sleeping

Locomotory system issues: Peripheral edema (swelling of hands, feet, and face)

Respiratory system issues: Nose bleeding, shortness of breath with exertion

Cardiovascular system issues: Persistent rapid pulse

If you encounter any of those signs and symptoms, it is important to stop your ascent and rest, and consider a descent of 500m or more. Treat the symptoms with analgesics and antiemetics as necessary, and consider the administration of acetazolamide (125 to 250 mg twice daily), otherwise known as 'Diamox'. Acute mountain sickness can progress to 'High-Altitude Pulmonary Edema' (HAPE) or 'High-Altitude Cerebral Edema' (HACE), both of which are potentially fatal.

Everest Base Camp Gamow bag
Testing out the Gamow bag at the TOPCOM conference. The Gamow bag allows medical practitioners to increase the air pressure that surrounds the patient in order to simulate a descent from altitude, which is the definitive treatment of altitude illness (AMS, HACE and HAPE).

Hape & Hace

High-Altitude Pulmonary Edema (HAPE) occurs when fluid leaks from the capillary beds in the lungs and into the alveoli, and causes swelling of lung tissue. HAPE tends to develop several days after arrival at moderate altitudes of (3000m to 4000m).

Mild HAPE: Dry cough, mild shortness of breath upon physical exertion

Moderate HAPE: Persistent cough, shortness of breath at rest, lung crackles

Severe HAPE: Mental status changes, respiratory failure, blood-tinged sputum, marked crackles

It is important to minimise exertion and to keep the patient warm before making an immediate descent. Initial administration of oxygen should be at a rate of 4-6 l/min until conditions improve, after which the rate is then lowered to 2-4 l/min. Moderate HAPE can quickly deteriorate into severe HAPE in a matter of hours, which will ultimately result in respiratory failure and eventual death. Pulmonary edema can sometimes persist for days after a descent has been made and quite often requires hospital observation and treatment.

High-Altitude Cerebral Edema (HACE) on the other hand, occurs when fluid leaks into the brain. This presents as brain swelling and an increase in intracranial pressure (ICP).

Mild HACE: Mild Headache, fatigue, nausea

Moderate HACE: Severe headache and vomiting

Severe HACE: Mental status changes and ataxia (lack of muscle coordination)

Oxygen should be administered at a rate of 2-4 l/min along with immediate descent and evacuation. Bear in mind that patients with severe HACE are unlikely to survive without aggressive intervention.

Nuptse at Everest Base Camp

Nuptse (elevation : 7861m) and the Khumbu Glacier nestled underneath

Next (Day 11) : Everest Base Camp (Part 2)
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