Case Study: Runner Begins Feeling Ill

The Setting

You and a friend are on a long run in the foothills of the Laramie Range in Wyoming. It’s a hot day. Four hours into the run your companion stumbles, slows, staggers, and sits on a log. He says he “feels awful.”

SOAP Report

Subjective

The patient is a 34-year-old male. His chief complaint is “feeling awful.” You are 6 hours into a planned 24 mile trail run at elevations ranging from 6,000-8,000 feet (1,800-2,400 meters).

Objective

Patient Exam

There is no mechanism of injury. Nothing unusual found on head to toe assessment. No edema, rashes, swelling, or bruises.

Vital Signs

History

Stop reading!

What is your assessment and plan? Take a few minutes to figure out your own assessment and make a plan. Don’t cheat—no reading on without answering this first!

Assessment

• Over-hydration (hyponatremia)?
• Hypoglycemia/fatigue?
• Heat Stress/Exhaustion?
• Altitude illness?

Plan

• Rest in the shade.
• Slow water intake.
• Eat more salty energy bars.
• Monitor for improvement. An evacuation decision is premature. We have 4 miles to go and 8 hours of daylight. This location is accessible by ATV or helicopter. We have a good cell signal.
• Interview the patient to assure we have a complete history.

Anticipated problems

The problem worsens. We are unable to continue.

Comments

These signs and symptoms are vague and could be any number of problems; over hydration, fatigue, hypoglycemia, altitude illness, and flu-like illness are at the top of your problem list. The history of water intake suggests over-hydration. Altitude illness is unlikely in this time frame unless the patient has a history of susceptibility to AMS or the altitude is really high (it’s not). The food intake may be low, so he might be hypoglycemic. We can’t rule out heat exhaustion, although the normal mental status suggests that heat stroke is not present. Maybe he’s just getting sick.

Interviewing the patient is a good idea—you might find out more about recent health, food intake, hydration, previous experience on endurance runs, etc.

Regardless, the treatment plan of resting in the shade, slowing water intake, and eating is appropriate for possible heat stress/exhaustion and hypoglycemia/fatigue. Limiting fluid intake until you have a better sense of his hydration status is a good plan.

The Tale Continues…

The interview with the patient reveals that their total water intake since 6:00 a.m. has been five liters. His plan was to start the day with “a full tank.” The patient ate the energy bars and the salt tablet and drank the water to keep his energy level high. He has no concept of the risk of over-hydration. He does have a history of “bonking” in previous multi-hour exercise sessions, which he attributes to not eating and drinking properly.

After an hour of rest with only sips of water, the patient urinates copious clear urine and states he can walk. The patient has not eaten due to nausea. He is A+Ox4 and says he no longer feels weird or shaky—he must have “hit the wall.” The patient reports a dull headache, but the dizziness has resolved. You begin to walk to the trail head. The day remains hot and you both are now very stiff from the hour of inactivity.

The walk to the trailhead is uneventful. The patient sips about 250cc of water en route, urinates copiously once more, and eats another energy bar. He arrives at the trailhead feeling tired and sore; in his words, “wasted.”

Comments

We don’t know exactly what was going on here. The patient never saw a physician. He convinced himself he had a touch of the flu. Our suspicion is over-hydration (hyponatremia), the subject of this discussion.

As a reminder, the primary risk factor for exertional hyponatremia (a relative low blood sodium due to dilution) is excess fluid intake. A common scenario is intake greater than 1-1.5 liters an hour for 4 hours or more. There may be influence from inappropriate anti-diuretic hormone levels causing fluid retention. NSAID (ibuprofen) use impacts the kidneys and is a concern, but this risk remains unclear.

We prevent exertional hyponatremia with judicious hydration. The mantras of “hydrate or die” or “drink to stay ahead of thirst” may get you into trouble. Thirst is a good indicator of fluid need, so “drink according to thirst.” Sodium supplements during exercise have not been shown to prevent exertional hyponatremia in the face of over-hydration.

Experience is critical. We must understand our individual fluid needs when we exercise in different environmental conditions.

Signs and symptoms of exertional hyponatremia vary among individuals and depend on the patient’s hydration and sodium levels. The patient may appear to have heat exhaustion: headache, weakness, fatigue, lightheadedness, muscle cramps, nausea with or without vomiting, sweaty skin, normal core temperature, and normal or slightly elevated pulse and breathing rates.

The field treatment of possible hyponatremia begins with an accurate fluid intake history. If over-hydration is suspected, then slow or stop fluid intake until symptoms resolve. Salty snacks are appropriate, but by themselves will not correct exertional hyponatremia. Have the patient rest in the shade with little or no fluid intake and a gradual intake of salty foods, while the kidneys reestablish a sodium balance. Brisk urine production usually indicates things are progressing in the right direction. Oral electrolyte replacement drinks are low in sodium and high in water, and may not help as much as you anticipate. Patients with neurological signs and symptoms, e.g. altered mental status, should be promptly evacuated.

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