Hyponatremia

It is a sunny, very hot and humid day. We are hiking along the peaks, when at about 3:30, we spot up ahead two hikers who look to be resting in the shade. As we approach them, one of them asks if we have any medical training. Hesitantly, you acknowledge that you are Wilderness Expedition Medics (and we suddenly begin to perspire a bit more heavily than we were a minute ago). She then explains that her friend, George, has grown increasingly ill over the last hour and she isn’t sure if he should be evacuated or if he can continue to their planned rest site.

George gives consent for examination – (after you put on blue gloves!)

George - 42 years old

P/C

- Complains that he is feeling nauseous and even vomited 30 minutes earlier

- Pounding headache (that he rates a 6 on the 10 scale)

- Fatigued and weak.

Students must:

- Introduce themselves

- Gain consent

- Wear appropriate PPE

- Mark the time

- Record his level of consciousness

- Record pulse

- Record respiration

- Record temperature

- Record BP

- Record O2 sats

- Comment on skin

- Take a detailed history to elicit more clues

Signs + Symptoms:

- Alert and Orientated - alert and oriented to person, place but showing some signs of confusion

- Pulse 68 bpm

- Respiration 16 rpm

- Temperature 37.9 C

- BP 120/75 mmHg

- O2 sats 99%

- Skin feels normal but continues to be very sweaty (even in comparison to yourself and friend).

Further history

- Allergic to penicillin

- Takes vitamins and herbal supplements daily

- No past medical history + denies any history of cardiac problems, looks otherwise to be in good shape.

- The two of them have been hiking since early this morning and that they have already covered about 12 miles, much of it marked by particularly hilly terrain.

- If asked if he has been drinking enough water, responds defensively that “of course” hydration has been his biggest priority and, as such, he hasn’t even really felt thirsty all day – In fact, he has been urinating normally and it has been clear (a sign of proper hydration).

- Ate a bowl of porridge for breakfast, and an apple and banana for lunch.

Diagnosis:

George is likely suffering from hyponatremia.

Results when the blood sodium level falls too low to maintain normal body functions. While this can occur in a variety of ways, in the outdoors context it usually results from drinking more than enough water while failing to eat enough (which would help maintain sodium levels). It is

Often referred to as “water poisoning,” but this is a misnomer since it implies one drinking huge quantities of water, when really one can actually just be drinking otherwise normal amounts.

This may sound like a really obscure illness, it is more common than many realise. It may typically be seen in those who are engaged in rigorous activities, especially when it’s hot, like running, biking, adventure racing, even hiking. In short, the kind of activities in which many of us plan to engage this summer, alone or with friends.

It is too often mistaken for other heat related issues, in particularly dehydration and heat exhaustion, and treated as such — the result of which can have nasty consequences for your patient.

Signs & Symptoms

Common complaints include nausea, vomiting, headache, weakness, fatigue, and muscle weakness.

Vitals may include sweaty skin, normal core body temperature, normal or slightly elevated pulse, and normal or slightly elevated respirations.

More severe symptoms can include diminished mental status, irritability, difficulty walking and maintaining balance. This condition may be fatal.

Treatment

Strong patient assessment skills are important so that you can best treat your patient.

Patients with normal mental status, and mild to moderate symptoms, may be treated in the field:

- Don’t give your patient any more fluids for the time being

- Rest in the shade

- Encourage a gradual intake of salty foods (like pretzels, crackers, beef jerky, or salted fruit slices - grim), while the kidneys re-establish a sodium balance. Crisps and nuts aren’t recommended due to their high fat content, and salt tablets are also not advised since they can induce nausea and vomiting.

- Continue to monitor your patient’s vital signs. Once your patient develops hunger and thirst combined with normal urine output, the problem is solved.

A patient with a deteriorating mental status needs to be evacuated immediately.

If diagnosis + treatment not reached in 10-15 mins – George deteriorates rapidly

New Signs + symptoms

- Severe confusion and unresponsive/unfollowing of commands

- Muscle cramps/weakness

- Drowsiness

- Pulse 92 BPM

- RR 20 rpm

- BP 90/65 – if fluids given – clarify HYPERTONIC SALINE

- Temp 37 C

- O2 99%

- Patient must be evacuated

Patient evacuation – Nearest evac point is 1km away – patient must be transported

Students must:

- Call mountain rescue

- Provide SBAR handover

- Maintain and monitor patient vitals

- Evacuate patient some distance safely – Tarpaulin carry?