TD Bank Beach to Beacon 10K Road Race
Protocols/Guidelines for Evaluation and Treatment of Dehydration and Heat Illness
Heat and Humidity
Heat cramping, heat exhaustion, heat syncope, and heat stroke are possible at any combination of ambient temperature above 80 °F (26.7 °C) and relative humidity above 40% (Kulka & Kenney, 2002). (See Figure 1)
Overview
· Dehydration. Some symptoms include muscle cramps, thirst, loss of energy, diminished performance and headache. Stretching can help relieve muscle cramps. To correct dehydration, administer sports drinks that contain sodium and electrolytes while providing rest in a shady area.
· Heat exhaustion. Some symptoms include headache, nausea, presyncope or dizziness, cramping, chills, and clammy skin. To treat, move the patient to a cool area, administer sports drinks and loosen or remove excessive clothing and equipment.
· Heat stroke. Characterized by high body temperature, confusion or unconsciousness. Seek emergency medical assistance first and then immediately ice down the patient.
Dehydration
Athletes in the heat can sweat 1-2 L per hour, and most athletes drink less than they sweat. The result is dehydration. Dehydration causing a loss of 2% body weight can impair physical performance (Walsh et al., 1994). Dehydration increases heart rate and decreases cardiac output. Perceived exertion increases as dehydration drains mental sharpness and willpower along with muscle power and endurance. Dehydrated runners also heat up faster (Latzka & Montain, 1999).
Fluid Replacement
If possible runners should be rehydrated with fluids (PO). Water and Gatorade will be available in the medical tent. A thorough history of the athlete’s hydration should be recorded. If a runner is suspected of hyponatremia (low blood sodium level caused by drinking excess free water), which is uncommon in 10K races, then excess free water/sports drink intake must be restricted. This includes all IV fluids. EMS staff must be alerted of this condition.
IV therapy will be started by a certified RN/IV therapist who is designated by the Medical Director. The IV will be started using a #22 or #18 gauge needle. The antecubital vein may be the best access if the runner is dehydrated. Only solutions of 0.9% of sodium chloride will be used to replace fluid volume. An IV will be started if the runner cannot take fluids orally, or if he/she is exhibiting signs and symptoms of heat illness.
NOTE: If a runner has had 2 liters of fluid and is not responding as expected, a physician should be asked to assess the runner for possible transport to a hospital.
Treating Heat Stroke ~ A Medical Emergency
Heat Stroke is a potentially life-threatening condition that must be treated promptly. When the body’s core temperature is very high, internal organs and brain cells begin to experience tissue damage, so fast core cooling is vital.
Early features are subtle central nervous system (CNS) changes, altered cognition or behavior, and body core temperature over 104-105 °F (40.0-40.6 °C). When an athlete collapses, the best gauge of core temperature is rectal temperature; oral, axillary, or ear canal temperature will not provide an accurate assessment of the athlete’s true temperature. Advanced features are collapse with wet skin, core temperature over 106-107 °F (41.1- 41.7 °C) and striking CNS changes (e.g., delirium, stupor, seizures, or coma (Roberts, 1998)).
Early Warning
Early warning signs of impending heat stroke may include irritability, confusion, apathy, belligerence, emotional instability, or irrational behavior. Giddiness, undue fatigue, and vomiting can also be early signs. Paradoxical chills and goose bumps signal shutdown of skin circulation, portending a fast rise in temperature. The runner may hyperventilate; this can cause tingling fingers as a prelude to collapse. Loss of coordination and staggering are all late signs, followed by collapse with seizure and/or coma. Upon collapse, core body temperatures at 108 °F (42.2 °C) or higher can be fatal.
Cool First
Field treatment consists of rapid cooling. No faster way to cool exists than submerging the athlete in an ice-water tub (submerging the trunk from shoulders to hip joints). Research suggests ice-water immersion cools runners twice as fast as air exposure while wrapped in wet towels (Armstrong et al., 1996). The U.S. Marines also use ice-water cooling (Kark et al., 1996). Recent field research with volunteer runners suggests cold water may cool as fast as ice water (Clements et al, 2002).
Monitor Closely
Check the athlete every few minutes for rectal temperature, CNS status, and vital signs. An indwelling rectal probe with a thermometer is useful. To prevent overcooling, remove the athlete from the tub when rectal temperature drops to 102 °F (38.9 °C). An athlete can be cooled from 108-110 °F (42.2-43.3 °C) to 102 °F (38.9 °C) in 15-30 minutes (Roberts, 1998).
Transport Second
Cool first, transport second. Send the heat-stroke athlete to the hospital after cooling. With rapid cooling techniques, survival rate approaches 100% (Kark et al., 1996). In fact, fast cooling can allow athletes to walk away in good health. For example, yearly at the Falmouth Road Race, up to 10-15 runners collapse with temperatures from 106-110 °F (41.1-43.3 °C), but over a decade nearly all such runners, after ice-water immersion, walked away. After cooling, runners are observed for 20-60 minutes to ensure they are drinking fluids and have normal vital signs and good cognition (Roberts, 1998).
Initial medical exam: Evaluation includes an assessment of two critical findings:
level of consciousness and body core temperature.
If the athlete is unresponsive, confused and disoriented--or exhibiting bizarre behavior or convulsions--heatstroke (or hypothermia depending on environmental conditions) or hyponatremia should be assumed to exist if no other obvious medical cause such as cardiac arrhythmia is discovered.
Evaluation should involve prompt assessment of body temperature.
If the athlete is conscious and coherent, postural hypotension may be assumed, and he or she should be placed in the recumbent position under a blanket with legs and pelvis elevated above the level of the heart. The athlete should be asked about any significant medical illnesses, drug allergies, any unusual symptoms during the day's event, and fluid intake during the race. If fluid intake has been excessive (more than 1 to 1.5 L/hr) and the athlete reports little urine production, fluid overload and hyponatremia need to be considered.
CHILDREN AT RISK FOR HEAT ILLNESS
There are several factors that make children more vulnerable to heat-related illness than adults.
· Children absorb more heat from their environment because they have a greater surface-area to body-mass ratio than adults – the smaller the child, the faster the heat is absorbed.
· Children are not able to dissipate as much heat through sweating as adults.
· Children produce more metabolic heat during physical activity.
· Children, like adults, do not have the physiological drive to drink enough fluids to replenish sweat losses during prolonged exercise.
Guidelines for Determining the Severity of a Collapsed Runner’s Condition
Immediate Assessment Not Severe Severe
Mental state Conscious Unconscious or altered
Alert Confused, disoriented, or aggressive
Rectal temperature < 40°C (104°F) 40°C (104°F)
Systolic blood pressure > 100 mm Hg 100 mm Hg
Heart rate < 100 bpm 100 bpm
Secondary Assessment
Blood glucose 4-10 mmol/L < 4 mmol/L or
Serum sodium 135-148 mmol/L < 135 mmol/L or > 148 mmol/L
Heat Index ChartFIGURE 1. Heat Index Chart. The heat index combines the effects of heat and humidity to arrive at an apparent temperature. Direct sunshine increases the heat index by 15°F.
Reprinted from the U.S. National Weather Service. Retrieved March 2002 from: http://weather.noaa.gov/weather/hwave.html#HeatIndexChart.
Revised 6-21-2010