Management of Exercise-Associated Hyponatremia: WMS Guideline update

Wilderness Medical Society has released its 2019 Update of Clinical Practice Guidelines for the Management of Exercise-Associated Hyponatremia. The same has appeared in the Journal of Wilderness and Environmental Medicine. 

Exercise-associated hyponatremia (EAH) has been recognized as an important cause of preventable morbidity and mortality in endurance and other physical activities throughout the world. It has been documented in hikers, trekkers, climbers, and cold climate endurance athletes also. Thus, EAH is not solely associated with activities in warm climates but is reported in both environmental extremes.

Major Recommendations are-

1. Participants and medical staff should be educated about proper hydration strategies for exertional activities. Recommendation grade: 1C.
2. Participants in endurance athletic events or strenuous wilderness activities should focus on avoiding overdrinking during the activity. Recommendation grade: 1A.
3. Participants should drink according to thirst, or they should determine an estimation of their individual fluid needs during pre-event training activities (by assessing body weight losses per hour), which limits the potential for weight gain. Recommendation grade: 1C.
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Sodium and/or salty snacks should be freely available for consumption along with the appropriate fluid intake, particularly in long, hot events in non–heat acclimatized persons, but this strategy will not prevent EAH when combined with overdrinking. Recommendation grade: 2B.
When available, point-of-care testing should be done on at-risk, symptomatic patients. If unavailable, integrate all available clinical and historical information into an assessment of the patient's hydration status (history of fluid intake, food intake, presenting signs and symptoms, body weight if available, and urine output). Recommendation grade: 1C.
Oral fluid restriction is indicated if EAH from fluid overload is associated with mild symptoms. Hypotonic fluids are contraindicated with suspected EAH. Recommendation grade: 1C.
Oral sodium in hypertonic solutions or foods with high sodium content (salty snacks) may increase serum sodium levels and enhance symptom relief (over fluid restriction) for mild EAH if tolerated. Recommendation grade: 2B
Observe patients for at least 60 min after exercise to ensure no decompensation from delayed symptomatic EAH after cessation of exercise. Recommendation grade: 1C.
IV hypotonic fluids are contraindicated with suspected fluid overload EAH. Recommendation grade: 1C.
Isotonic fluid intake should be restricted in known or suspected severe hypervolemic EAH until urination begins. Recommendation grade: 1C.
An IV bolus of 100 mL of HTS should be administered immediately if signs and symptoms of encephalopathy (with or without noncardiogenic pulmonary oedema) develop and severe EAH is strongly suspected. Recommendation grade: 1C
When transferring care, receiving caregivers should be alerted to the potential diagnosis of EAH and appropriate fluid management (withhold hypotonic fluids). Recommendation grade: 2C.
Oral and IV hypotonic or isotonic hydration should be avoided early in the management of EAH, although it may be appropriate in certain clinical contexts once sodium correction has been initiated or hypovolemia is confirmed. Recommendation grade: 1C.
With suspected EAH, and particularly in those with altered mental status, sodium estimation should be obtained as rapidly as possible after hospital arrival. Recommendation grade: 1A.
A rapid assessment for signs and symptoms of cerebral edema or noncardiogenic pulmonary edema should be done in all patients with possible EAH. Recommendation grade: 1A.
Severe EAH biochemically confirmed or symptomatic EAH should be treated with a 100-mL bolus of IV HTS, which can be repeated twice at 10-min intervals (3 doses in total) or until improvement of neurologic symptoms, with the aim of acutely increasing serum sodium concentration by about 4 to 5 mmol·L-1 and reversing cerebral oedema. Recommendation grade: 1A.

There is an ongoing need for education to ensure that participants understand the risk of overhydration. Furthermore, a knowledge gap persists internationally among practitioners and prehospital EMS personnel about the assessment and treatment of EAH, which is compounded by many of its nonspecific presenting signs and symptoms.

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DOI: https://doi.org/10.1016/j.wem.2019.11.003