Crushing Muscle Injuries

By Austin Chapin III, RN

 

Rhabdomyolysis and crushing injuries

Hello and welcome, I have a very interesting subject in which to share with you. As we journey through our career in emergency medicine we are sooner or later going to be called upon to care for a patient with a crush injury and possibly Rhabdomyolysis. This little devil can be fatal if not handled properly. Let’s re-discover this particular ailment and learn together how to subdue this beast.

What you didn’t see in 127 hours, muscle damage after rock crushing his arm.

I got the idea for this article from a recent viewing of the movie 127 hours. Without spoiling the film to much I will give a brief description. A man, an avid rock climber that doesn’t believe in the buddy system is in a canyon all by himself. He falls 10 feet down into a very large opening in the rock. As he falls a large boulder falls with him pinning him to the wall and crushing his arm. He remained stuck in the canyon for 127 hours. Ok bad situation right? His arm is crushed and all the muscle tissue in his arm that isn’t getting proper circulation is dying. There are several reasons why crush injuries are dangerous. It’s not just that muscle tissue is destroyed; it’s much worse than that!!

To understand crushing injuries we must first understand muscles. Muscles are grouped into bundles like cables. If you were to look at a cross section of a large electrical cable you would see a large tube with smaller tubes all bound together. Muscles are held together by groups of tough rubber-band like tissue called fascia. This material keeps everything together but it doesn’t allow for much expansion…that’s where our problem lies with a crush injury.

Legs have 4 muscle compartments

Large muscle groups like your lower extremity have compartments of muscle fibers. These compartments are bundles within bundles. Your lower legs have (4) compartments and your arms have two. I’m just going to talk about the leg compartments for now. They are the Anterior, lateral, superficial posterior, and the deep posterior. Since the most common site for this injury is the anterior compartment I will concentrate on it. Don’t worry about memorizing those you can just carry this article around with you, all the time. Ha Ha.

Now let’s talk about how muscle tissue works. Muscle fibers contain many proteins but I’m only going to discuss a few. Actin and Myosin are the driving proteins for muscle fibers. They grab on to each other and pull. Muscle tissue works kind of like a group of people in a long boat forced to play tug of war with another long boat. And let’s say they are floating on the blood stream.  The rope is Actin it has little knots on it for the people to grab. The people’s hands are the myosin. Of course nothing happens until big man Calcium comes into the room.

Calcium is boss!

Calcium is the boss and he hangs out in his office the sarcoplasmic reticulum or (SR) for short. He is the whip cracker of the whole process. When he comes running into the room everybody grabs the rope and starts pulling. Heave Ho! Heave HO! When they pull on the ropes the boats get closer together and the muscle gets shorter and you smack that mosquito that’s biting your arm. Oh!! And on the boats are barrels of potassium. This will become important later in this article. That’s the short version of muscle physiology. Now what is Rhabdomyolysis? And what does it have to do with a muscle injury?

The Steadman’s Medical dictionary describes Rhabdomyolysis as “an acute fulminating potentially fatal disease of the skeletal muscle that entails destruction of the muscle as evidenced by myoglobiemia or myoglobinuria”.  Well there you go right??! Clear as mud. What is Myoglobin? And how does it get into the blood and urine?  Myoglobin is the oxygen storing red-pigment of muscle. The protein is similar to hemoglobin specific to muscle tissue. It carries oxygen to the muscle cells. It would be like the refreshment person for the rope pullers on the boats. When it released into the blood it can clog up the nephrons and cause acute Kidney failure. This can render the kidneys inoperable and predisposes the patient to a fatal outcome.

OH NO!!!! my leg is caught!!

So here is the situation, a patient is a factory worker and gets their leg pinched between two heavy machines. Inside their leg the boats have been smashed and knocked over. All the rope pullers and the refreshment people (myoglobin) are floating in the blood stream heading for the kidneys. Oh No!!! right? All those people can’t fit into those tiny nephrons. Kidneys start backing up. Back at the boats fluid is filling the whole area closing off the whole blood supply, just damming everything up. And guess what also was inside of the now destroyed boats, the barrels of Potassium. Potassium is spilled out of the cells into the blood stream creating a whole new problem, Hyperkalemia.

The Patient is now experiencing pain from the increased swelling. Because of the tissue damage the patient’s own histamine response sends more fluid to that area creating more pressure. The affected area is getting tighter and tighter. Remember the strong banding material around the muscle fibers that don’t allow for much expansion? Now the blood supply to the muscle tissue is compromised and compression on the nerves begins to kill the peripheral nerves that supply the distal area. Death of the nervous tissue can happen very quickly. So, on the outside this person looks as though they are ok. No big deal, just some swelling in the lower limbs right? Maybe they have a fracture, maybe they don’t, but reality is that they are in danger of losing life and limb literally. This condition is known as compartment syndrome.

Compartment syndrome happens

There are other situations that can cause compartment syndrome, here are a few; burns, (especially circumferential), tightening of the skin with increased inflammatory response, animal bites-large amounts of tissue damage + infection, Air-splints or cast that are too tight, BP cuff, and some medications like aminoglycosides and anticoagulant therapies.   Remember this! With compression injuries, 0xygen to the tissues and nerves decreases exponentially the closer it gets to the patients Mean Arterial Pressure (MAP).

Know the signs and symptoms

Signs and symptoms for compartment syndrome are as follows: out of proportion pain for the injury, or if wearing a cast, the inability to control patient’s pain. Distal Paresthesia– can’t feel their toes/fingers means nervous tissue is compromised. Pallor/decreased capillary refill– although this is a late sign you should be monitoring distal pulses. Some departments will have specialized equipment to monitor compartment pressure in the limb. In the ER setting we don’t have such equipment.

Labs to watch for!!

Some labs you may want to watch for: elevated CKP >1000 and an elevated potassium level, Myoglobinuria and dark stained urine. Remember myoglobin is the red pigment in muscle! Think of this situation like a heart attack of the limb, it’s the same principle…time is muscle.

Treatment should be started as soon as possible due to the danger of the patient losing a limb or cardiac complications from hyperkalemia, and kidney failure. The object is to flush the kidneys of myoglobin before too much damage is done.#1. Initial nursing response should be two large bore IV’s and begin infusing NS rapidly. Be mindful of the patient with CHF and fluid overload. The Midlevel or the MD will guide you on the amount to infuse and rate. Just get it going this is an emergency.#2. Place Ice on affected areas and elevate extremity to reduce swelling.#3. Continue to assess neurovascular integrity every 15 min.

In conclusion, I hope this article has made more since of this material and brings to mind the gravity and seriousness of compression injuries. The possibility of death or becoming permanently disabled makes this a true emergency. Thank you for your time and input on these articles I enjoy writing them and I enjoy researching the material. And for all you CEN candidates hopefully I can help you as well.

Austin F. Chapin III, ASN, RN.

Reference materials

  1. Stracciolini, MD. & E. Hammerburg, MD. (March 7, 2012). Acute Compartment Syndrome. Retrieved on 7/17/2012 from http://www.uptodate.com
  2. T. Fischbach, RN, BSN, MSN. & M.B. Dunning III, BS, MS, PhD. (2006) Nurses quick reference to: Common Laboratory & Diagnostic test. 4th ed. Pg. 175 Lippincott Williams & Wilkins, Philadelphia, PA.
  3. Fults, RN, BSN, CEN, CFRN. & P. Sturt, RN, MSN, CEN. (2005) Mosby’s Emergency Nursing Reference 3rd ed. Elselvier Mosby. pgs. 395-399.
  4. Miller, MD. (June 12, 2012) Causes of Rhabdomyolysis. Retrieved on 7/17/2012 from http://www.uptodate.com
  5. Vanholder, MD, PhD.& M.S Sever, MD. (December 19, 2012) crush related acute kidney injury. Retrieved on 7/17/2012 from http://www.uptodate.com
  6. Stedman’s (2008) Medical Dictionary for the Health Professional and Nursing. 6th Wolters Kluwer/Lippincott Williams& Wilkins, Philadelphia, PA.

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