RESOURCESFire ScienceThe Science Behind Rhabdomyolysis and the Firefighter

The Science Behind Rhabdomyolysis and the Firefighter

Fruita, United States – November 24, 2021: A beautiful shot of wild land firefighters overlooking a training exercise in Fruita, US

By: Dr. Brittany S. Hollerbach – Center for Fire, Rescue & EMS Health Research, NDRI-USA, Inc., First Responder Center for Excellence

The signs and symptoms of rhabdo can often mimic those associated with heat illness. Heat illnesses can occur when the body is exposed to extreme heat or prolonged work in hot environments.

Rhabdomyolysis, or “rhabdo” for short, has been a topic of discussion in the fire service for years 1–3. In December 2021, an FDNY probationary firefighter died during training due to rhabdo4. There is a potential risk of heat stress and subsequent illness or injury to anyone working in extreme heat. Firefighters (including structural, wildland, and wildland-urban interface or WUI) have increased risk due to the nature of their occupation3. Job factors that can increase rhabdo risk include elevated core body temperature (working in extreme temperatures, exposure to fire, performing physically strenuous work), traumatic injuries, overuse injuries, and dehydration3. It is imperative that firefighters understand what rhabdo is and recognize its signs and symptoms. 

The breakdown of muscle tissue

Rhabdomyolysis is a complex medical condition defined by the breakdown of damaged muscle resulting in the release of muscle cell contents like proteins and electrolytes into the blood3,5. Rhabdo cases range in severity from an asymptomatic elevation of creatine kinase (CK) levels in the blood to severe life-threatening cases associated with extremely high levels of CK, myoglobinuria and acute kidney failure5. For firefighters, risk factors include heat exposure, extreme physical exertion or excessive muscular activity, and direct trauma (like a crush injury from a fall). Rhabdo can be misdiagnosed as heat stress or dehydration as the presenting signs and symptoms can be similar. 

Signs and symptoms of rhabdo

The signs and symptoms of rhabdo can often mimic those associated with heat illness. Heat illnesses can occur when the body is exposed to extreme heat or prolonged work in hot environments. Exercise-induced increases in core body temperature can negatively impact performance and may lead to the development of heat-related illnesses including heat exhaustion, heat cramps, heat rash, or even heat stroke. Firefighter personal protective equipment (PPE) is thick and fully encapsulating and can therefore increase heat stress. It is important for firefighters to remember to take breaks often and employ cooling strategies. When firefighters perform extreme work or push their bodies beyond what their muscles are capable of, they are susceptible to rhabdo. The more strenuous or prolonged the exercise/activity, the more damage that is incurred. Excessive muscular activity results in a state in which the body’s energy production cannot keep up with the extreme demand depleting cellular energy stores leading to a disruption of the muscle cell membranes (literally breaking the muscle down). Factors that further increase the risk of rhabdo include low levels of potassium (often from excessive sweating), extreme heat and humidity, exercise-induced asthma, and pre-exertion fatigue5

Rhabdo and Structural Firefighters

Structural fire response and training involves exposure to heat and prolonged, intense exertion. These factors increase the risk for rhabdomyolysis. The Health Hazards Evaluation (HHE) Program is a division of the National Institute for Occupational Safety and Health (NIOSH) and is responsible for investigating health hazards in the workplace and recommending ways to reduce hazards and prevent work-related illness. In 2019, the HHE evaluated the risk of heat related illness and rhabdomyolysis and found that both fire cadets and instructors were at increased risk. They also found that additional training is necessary regarding heat-related illness and rhabdo to increase early recognition and reduce modifiable risk factors6

Rhabdo and Wildland Firefighters

In the profession of wildland firefighting there has been a rise in the occurrence and awareness of exertional rhabdo. From 2008-2016, 26 cases of rhabdo were reported for wildland firefighters. Seven cases were reported in 2016 alone, more than any previous season. Of note, six out of the seven cases in 2016 occurred during pre-season training. Three of the six cases occurred on the first day of training. The increase in rhabdo prevalence among wildland firefighters could be due to more extreme wildfire conditions causing more frequent cases or due to more education and awareness of the condition. Regardless, it’s important to address the issue and be aware of the risks, signs, and symptoms.

Awareness of High-Risk Behaviors

As a firefighter, it’s important to be aware of high-risk activities and behaviors. Some risk factors are unavoidable parts of the job while others are modifiable things firefighters can change. Physical activity, especially when strenuous and unaccustomed, can cause damage and subsequent muscle fiber breakdown, known as exertional rhabdo. It is important that recruit and incumbent firefighters alike be physically prepared for the arduous demands of the job. During training and fire suppression, firefighters engage in strenuous activity and prolonged exertion often under extreme temperatures or harsh environmental conditions on dangerous terrain. The nature of this work puts them at an increased risk for rhabdo. 

Balancing the needs of firefighting with your health

Firefighters must keep in mind the cumulative effects of training or long bouts of fire suppression activities, in addition to ambient temperatures and the strenuous nature of the job. On-scene rehabilitation is imperative for structural firefighters. The IAFF produced a manual outlining the effects of thermal stress on fire fighters more than 25 years ago7–9. Rehabilitation remains an essential element on the incident scene to prevent more serious conditions – such as heat exhaustion or heat stroke – from occurring. NFPA 1584: Standard on the Rehabilitation Process for Members During Emergency Operations and Training Exercises outlines important information and should be adopted by fire departments and reviewed by firefighters. Moderation and rehabilitation are also important for wildland and WUI firefighters. For example, wildland early season training often involves physical fitness testing with sprinting followed by a practice hike. Supervisors should take note of the environmental conditions, the physical fitness status of trainees, and encourage hydration, appropriate nutrition, and sufficient rest periods to avoid exertional rhabdo.

Personal risk factors of rhabdo

In addition to fire ground and training risk factors, there are personal risk factors to be aware of. Some risk factors are out of the firefighter’s control such as over-the-counter medications and certain antibiotics. Medications, antibiotics, caffeine, and even supplements are filtered through the kidneys. Creatine supplements are widely used by athletes and firefighters who require muscle power in a short time and to increase muscle mass10. The intake of 20-25 g/day of creatine for 5-7 days is recommended11. However, over 80% of athletes appear to take much larger quantities than recommended10. Excessive intake may cause an imbalance in body water, triggering muscle cramps or dehydration, which may be the root cause of exertional rhabdo11

The kidneys are also responsible for flushing the proteins released from damaged muscles after exercise. If the kidneys become overloaded, this is when the body can be at risk for rhabdo. Firefighters should consult with their physician to ensure they are taking the appropriate steps to remain healthy, hydrated, and prepared to do the job. 

Here’s a list of items to avoid3,5

(Firefighters should consult with their physician before making any medication changes)

  • Over-the-counter medications such as decongestants and antihistamines
  • Certain antibiotics
  • Dietary supplements such as creatine
  • Some weight loss products
  • Cholesterol-lowering drugs known as statins
  • Excessive intake of caffeine and other stimulants
  • Excessive alcohol consumption (even off-duty)
Rhabdo Signs & Symptoms

Rhabdo may cause muscle pain, aches, or weakness – this is referring to muscle pain/weakness beyond what one would typically expect from a difficult workout, training evolution, or fireground task. Rhabdo can also cause full-body fatigue, feeling weak or tired, or being unable to complete regular tasks or workouts. It also may can cause fever, rapid heart rate, nausea, vomiting, confusion, and lack of consciousness5. Also pay attention to muscle or limb stiffness/swelling or decreased range of motion. 

Monitor your urine. Dark, reddish urine (tea or cola-colored) or decreased amounts of urine can be indicative of rhabdo. 

It also is important to remember that it is possible to have rhabdo and not show any signs or symptoms. It is imperative firefighters be aware of these sign/symptoms and pay attention to their body. If one suspects they may have rhabdo, stop current activity, alert the crew, supervisor, or trainer right away about any symptoms and seek care at the nearest medical facility. Firefighters should inform doctors of their occupation as a firefighter, specifically what the firefighter was doing, and ask to be tested for rhabdo. Remember that reporting symptoms is never a sign of weakness and early detection could save the firefighter’s career and life.

Prehospital care for firefighters in rhabdo

Prehospital care for potential rhabdo includes a normal assessment of ABC’s (airway, breathing, circulation), oral hydration if tolerant, and IV fluids5. Once at the hospital or doctor’s office, aggressive IV rehydration is imperative. A serum creatine phosphate (CK or CPK) test should be performed to ensure early diagnosis. This is the only definitive test for rhabdo. Urinary dipsticks to check for myoglobin in the absence of red blood cells are not an accurate screening tool for rhabdo. Aggressive treatment should start as soon as possible and healthcare providers should continue to test CK levels until two consecutive tests show levels lowering. Fluid intake and urinary output should be continuously monitored. The limbs should be checked for compartment syndrome, and central venous pressure should be monitored5. Following a diagnosis of rhabdo, the firefighter should maintain aggressive hydration including electrolyte replacement and get lots of rest. Rhabdo is serious and can have long-term effects if the firefighter does not receive early treatment. If left untreated, rhabdo can lead to kidney damage or failure, dangerous heart rhythms, seizures, permanent disability, and even death. 

Firefighter resources

There are resources for the fire service from the First Responder Center for Excellence (FRCE) and such as a wallet card from  NIOSH/CDC. On the FRCE website firefighters can find a brief training on rhabdomyolysis as well as an informative infographic and model heat safety policy. NIOSH/CDC offers a firefighter-specific wallet card. Firefighters are encouraged to carry it with them in the event they ever have to be treated for rhabdo. The card can be found by going to the NIOSH/CDC website (https://www.cdc.gov/niosh/topics/rhabdo/resources.html). This card can also be found on the FRCE website (https://www.firstrespondercenter.org/resource-menu-do-not-remove/202-cardiac). 

Importance of hydration

There are a number of important considerations for hydration. Note that dehydration does not cause rhabdo but it can make it worse. Dehydration impairs the body’s ability to get rid of muscle proteins and electrolytes released into the blood stream with intense work. The general recommendation is to drink 2-4 mL (0.07-0.14 oz) of water per pound of bodyweight 2-4 hours before activity12. This equates to about 10.5-21 oz for a 150-pound individual. Additionally, be sure that your beverage provides some electrolytes, such as sodium, that are lost in sweat. Studies conducted on wildland firefighters indicate that during fire suppression activities, FFs need to drink a minimum of one quart (32 oz) of liquid EACH HOUR of work13,14. Monitor and encourage adequate fluid intake and rest breaks. Keep this urine chart handy – ideally your urine should be nearly clear meaning you are well hydrated. Dark, reddish urine indicates severe dehydration. 

Well balanced training for firefighters

Understandably, training for fire suppression operations is intense but it is important for supervisors, trainees, and others to design an appropriate workout and testing progression to reduce the risk of adverse events such as rhabdo and injury. Even large group workouts can be scaled for individuals so everyone is working at an individually appropriate intensity level. Supervisors or those leading workouts should give cues for proper form and technique and use levels of perceived exertion as goals for the intensity of the workout. For example, 65% of the maximal effort is different for everyone. Proper progression is extremely important as is programming flexibility and recovery into workouts15. As a department, it is important as recruits join the department or as the weather warms, that firefighters get acclimated to what may be a new level of physical activity before working for long periods of time in the heat. When training (whether on or off-duty, in camp or during your off season), vary repetitions, sets, weight, and exercises over time to advance goals and avoid overtraining. Always ensure proper exercise technique. Rhabdo can occur regardless of one’s fitness level or daily habits. 

Prevention of rhabdo

Remember that prevention is always better than treatment. The most important thing is to be aware of the things that put firefighters at increased risk. Firefighters should acclimate their bodies to physical activity before intense bouts of exercise as a new recruit, in training camp or working on the fire ground. This means training off-duty and in the off-season (for seasonal wildland firefighters). Stay hydrated. Limit caffeine and go for low-sugar beverages. Also enhance your intake of electrolytes to replace those lost in sweat. Avoid dietary supplements such as creatine as with increased work it can be hard for your kidneys to filter it out. When on the fireground, modify work/rest periods to give your body a chance to rid excess heat and recover. In summary, it is imperative that firefighters are aware of the signs and symptoms of rhabdo and are adequately prepared for the physical nature of the job. Firefighters should know their ‘normal’, prepare before it is time to work, ramp-up physical activity slowly, hydrate often, recognize the signs/symptoms of rhabdo and other serious heat illnesses, and seek medical attention immediately if they or a crew member thinks they might have rhabdo. 

References

1. MMWR. Exertional Rhabdomyolysis and Acute Renal Impairment — New York City and Massachusetts, 1988. CDC; 1990:751-756. https://www.cdc.gov/mmwr/preview/mmwrhtml/00001812.htm

2. West M, Domitrovich J, Symonds J. Rhabdomyolysis in Wildland Fire: A Review of Reported Cases. National Technology & Development Program; 2016. https://wildfiretoday.com/documents/Rhabdo_5_9_16.pdf

3. NIOSH. Rhabdomyolysis in Structural Fire Fighters: A Patient Population at Risk.; 2018. https://www.cdc.gov/niosh/docs/2018-134/

4. Keogh E. Cause of Death Revealed for Probationary FDNY Firefighter Who Died during Training Exercise. New York Daily News; 2022. Accessed November 11, 2022. https://www.nydailynews.com/new-york/ny-cause-of-death-fdny-probationary-firefighter-20220528-g3h7pll7mvemfi3kboocmesjwa-story.html

5. Khan F. Rhabdomyolysis: a review of the literature. Neth J Med. 2009;67(9).

6. Eisenberg J, Li J, Feldmann K. Evaluation of Rhabdomyolysis and Heat Stroke in Structural Firefighter Cadets. NIOSH; 2019. https://www.cdc.gov/niosh/hhe/reports/pdfs/2018-0154-3361.pdf

7. IAFF. Thermal Heat Stress Protocol for Fire Fighters and Hazmat Responders.; 2000.

8. IAFF. Emergency Incident Rehabilitation Program. Published N.D. https://www.iaff.org/emergency-incident-rehab/

9. U.S. Fire Administration. Emergency Incident Rehabilitation. FEMA; 2008. https://www.iaff.org/wp-content/uploads/EIRP/Files/USFA-IAFF-Emergency-Incident-Rehabilitation-Manual-2010.pdf

10. Juhn M, O’Kane J, Vinci D. Oral creatine supplementation in male collegiate athletes: a survey of dosing habits and side effects. J Am Diet Assoc. 1999;99:593-595.

11. Kim J, Lee J, Kim S, Ryu H, Cha K, Sung D. Exercise-induced rhabdomyolysis mechanisms and prevention: A literature review. J Sport Health Sci. 2016;5:324-333.

12. USADA. Fluids and Hydration. Published N.D. https://www.usada.org/athletes/substances/nutrition/fluids-and-hydration/

13. NWCG. Hydration. Published 2022. https://www.nwcg.gov/committee/6mfs/hydration

14. NWCG. Safety Advisory: Rhabdomyolysis Epidemiological Study Results and Recommendations. National Wildfire Coordinating Group; 2011. http://www.wildlandfire.com/docs/2011/safe/rhabdo.pdf

15. Kraemer W, Ratamess N. Fundamentals of resistance training: progression and exercise prescription. Med Sci Sports Ex. 2004;36(4):674-688.

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