Muscular claustrophobia

aka Bone and Joint Bamboozler 002

A 27 year-old man sustained an undisplaced midshaft fracture of his left tibia after his girlfriend inadvertently (or so she said…) backed into him in her car, with the rear bumper pinning his leg against the car behind.

Following an orthopedic consult, he was put in a long leg cast and sent home, with orthopedics follow up arranged for the next day.

Overnight he re-presented to the emergency department with increased pain in his leg and paraesthesiae in his toes. The cast was removed. Peripheral pulses were intact, but the anterior compartment of the leg, in particular, was tense and tender to palpation.

He was taken to the operating theatre in the middle of the night after an anterior compartment pressure measurement of 60 mmHg was obtained.

[Case modified from Perron et al (2001)]


What types of injuries may cause a compartment syndrome?

Bamboozler Answer

Type of injury

Fractures: account for about 75% of compartment syndrome. Most commonly the tibia, humeral shaft, combined radius and ulna fractures, and supracondylar fractures in children. May be open or closed.

Soft tissue injuries such as:

  • crush injury
  • snake bite
  • excessive exertion
  • prolonged immobilisation
  • constrictive dressings and plaster casts
  • soft tissue infection
  • seizures
  • extravasation of intravenous fluids and medications
  • burns
  • tourniquets

Patients with a coagulopathy are at particular risk of compartment syndrome.


Compartment syndrome usually affects what parts of the body?

Bamboozler Answer

Most commonly affected are the:

  • forearm (volar compartment)
  • leg (the anterior compartment — the anatomical leg being the bit below the knee…)

Compartment syndrome can occur in other regions, including the back, buttocks, thigh, abdomen and foot.

Compartment syndrome of the deep posterior compartment of the leg is easily missed.


What is the pathophysiology of compartment syndrome?

Bamboozler Answer

Muscles are contained within inelastic fascial sheaths.

When injured muscles swell, a hematoma forms, or external compression is applied, the pressure within the fascial compartment increases.

If the pressure rises high enough, capillary pressure is exceeded and circulation is compromised.

This results in ischemic injury to the muscles and nerves within the fascial compartment.


How quickly does irreversible injury occur with compartment syndrome?

Bamboozler Answer

Ischemic injury to muscles and nerves occurs after 4 hours of complete ischemia.

This becomes irreversible at some point over the next 4 hours (i.e. 4-8 hours after the onset of ischemia), resulting in local rhabdomyolysis and neuropraxis progresses to axonotmesis as nerve injury worsens.


What are the clinical features of compartment syndrome?

Bamboozler Answer

Remember the 6P’s:

  • Pain (especially on passive stretching)
  • Pallor
  • Perishingly cold
  • Pulselessnessaralysis
  • Paraesthesiae

Pain is the key symptom. It occurs early, is persistent, tends to be disproportionate compared with the original injury and is not relieved by immobilisation. The pain is exacerbated by passive stretching, which is the most sensitive sign.

The affected compartments may feel tense and tender on palpation. Assess loss of sensation by light touch and two-point discrimination, rather than just pinprick, which is less sensitive.

Measure compartment pressures if compartment syndrome is suspected — do not rely on clinical signs — have a high index of suspicion!


Phew, I can feel pulses, the patient can’t have compartment syndrome. Right?

Bamboozler Answer

No, wrong.

Palpable distal pulses and normal capillary refill does not exclude compartment syndrome.

…sorry.


What is the most reliable pressure indicator of compartment syndrome?

Bamboozler Answer

Normal tissue pressure ranges between zero and 10 mmHg.

Capillary blood flow within the compartment may be compromised at pressures > 20 mmHg.

Muscle and nerve fibers are at risk for ischemic necrosis at pressures >30 to 40mmHg.

These pressures may still be tolerated — depending on the perfusion pressure, hence a recent trend towards using delta pressures, although most treatment recommendations are still based on absolute pressures.

A delta pressure < 30 mmHg

• Delta pressure = diastolic blood pressure (DBP) — intracompartment pressure.
• A delta pressure <20 mmHg is a definite indication for fasciotomy, <30 mmHg may be a relative indication.

Other recommendations for fasciotomy include:

  • clinical signs of acute compartment syndrome
  • absolute pressure is >30 mmHg and the clinical picture is consistent with compartment syndrome
  • arterial perfusion has been interrupted for 4 or more hours.

Pulse oximetry is insensitive and is not recommended in the detection of compartment syndrome.


How can compartment pressure be measured?

Bamboozler Answer

A commercial device like the Stryker STIC Device is probably the easiest and most accurate means of measuring compartment pressures.

 – At least with tibial fractures, measurements should be taken in both the anterior and deep posterior compartments at the level of the fracture as well as at proximal and distal locations to reliably determine the highest tissue pressure measurement.  – This measurement should be used to determine the need for fasciotomy.

Compartment pressures may also be obtained using an angiocath connected to a blood pressure transducer (e.g. arterial line set up).

Other options for measuring compartment pressures include the needle technique, the wick catheter, and the slit catheter. Perron et al (2006) describe the needle technique as follows:

  • The needle technique has the advantage that it can be performed with items that are readily available in every ED.
  • An 18-gauge needle is attached to an intravenous extension tube and then to a stopcock.
  • Approximately half the tubing is filled with sterile saline — being certain that air is not allowed into the tubing.
  • A second intravenous extension tube is attached to the 3-way stopcock with the opposite end attached to the blood pressure manometer.
  • The needle is then placed in the compartment and the apparatus kept at the level of the needle.
  • The stopcock is then turned so that it is open in the direction of the intravenous tubing on either side of a syringe.
  • The syringe filled with air is slowly compressed, causing air to move into both extension tubes.
  • The meniscus created by the saline in the extension tube attached to the 18-gauge needle is watched carefully for any movement.
  • As soon as movement occurs in the fluid column, the compartment pressure is read from the blood pressure manometer.
  • This technique, although simple to perform with minimal equipment, may be inaccurate.

What is the emergency management of compartment syndrome?

Bamboozler Answer

Management involves these measures:

  •  arrange immediate fasciotomy (i.e. wake up the poor on-call orthopod!)
  • remove all constrictive dressings.
  • elevate the limb to the level of the heart.
  • consider injury specific measures:relieve flexion of the elbow if the forearm is involved.
  • apply traction for a partially reduced supracondylar fracture.
  • if there is no relief within 30 minutes, go straight to the operating theatre.
  • provide adequate analgesia and IV hydration to maintain an adequate urine output in case of rhabdomyolysis.

What serious complications can result from compartment syndrome?

Bamboozler Answer

These are the ‘biggies’:

  • gangrene or loss of limb viability requiring amputation
  • ischemic contracture and loss of function
  • rhabdomyolysis and renal failure

What is the clinical significance of this sign?

Bamboozler Answer

Volkmann Contracture

The German surgeon Richard von Volkmann described Volkmann’s ischemic contracture in 1881 – he is also known for his spoon, his splint and his triangle.

His contracture is the booby prize for taking the ‘middle road’ between fully recovering from an ischemic injury and complete necrosis resulting in gangrenous demarcation of damaged tissues.

It occurs in 1-10% of cases of compartment syndrome.
Certain compartments that are particularly sensitive to ischemia become necrotic and are replaced by fibrous tissue, even though more distal tissues are spared.

Volkmann’s contracture affects the volar compartment of the forearm, but the same process may affect the anterior tibial, peroneal or deep posterior compartment of the leg.

When the volar forearm is affected the forearm is withered, the MCJs are hyperextended and the IPJs are flexed forming a useless claw.

The fingers can be straightened when the wrist is fully flexed.
There may be fixed flexion deformities at the wrist and elbow joints.


References

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Bone and Joint Bamboozler

Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also the Innovation Lead for the Australian Centre for Health Innovation at Alfred Health and Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of two amazing children.

On Twitter, he is @precordialthump.

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