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Compartment Syndrome

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April 22, 2015

Compartment Syndrome |

Compartment syndrome

It is a limb and life threatening condition observed when the perfusion pressure falls below tissue pressure in a closed anatomic space. Untreated compartment syndrome leads to tissue necrosis, permanent functional impairment and if severe renal failure and death.

Possible treatment pitfalls

Failure to measure compartment pressures
Failure to investigate rhadbomyolysis (muscle breakdown) if suspected.
Failure to properly measure pressures in the compartment as needle may be placed in a tendon or fascia or the wrong compartment.

Prognosis

This depends on the time lapse between occurrence and treatment and whether complications develop.

Pre-hospital care

Compartment syndrome develops rapidly after arterial injury. The speed of transport is important.

Emergency department care

  • Time is vital and we have only 6 hours before irreversible nerve damage occurs due to intracompartmental hypertension. On suspecting perform pressure measurements immediately.
  • Ischemic injury is the basis of compartmental syndrome.
  • Oxygen should be given to increase the partial pressure of oxygen (PO2).
  • Keeping the limb level with the body reduces the arterial pressure without changing the intracompartmental pressure.
  • Do not elevate the affected leg. After elevation of 35 cm there is a reduction of the mean arterial perfusion pressure of 23 mmHg with no change of intracompartmental pressure.
  • Intravenous hydration is essential. Hypovolemia worsens ischemia.
  • Fasciotomy is definitive therapy and is well documented as a limb saving technique

varicose veins

Fasciotomy leg with external fixation

Controversies regarding fasciotomy

  • Timing of fasciotomy
  • It extends hospital stay
  •  Changes closed injury into open injury increasing chances of infection
  •  Debate on when to perform fasciotomy – some perform at 30mm Hg compartmental pressures while others use 45 mm Hg  as cut off pressure. Still others do prophylactic fasciotomy at normal pressures to prevent compartment syndrome.

Delta-p as an indicator for fasciotomy

Delta-p is a measure of the perfusion pressure (diastolic blood pressure minus intracompartmental pressure). Delta-p pressures < 30 mm Hg were used as criterion for fasciotomy with good results. Thus many patients with intra compartmental pressures > 40 mm Hg did not undergo fasciotomy because their delta-p pressure was > 30 mm Hg. However patients with intra-compartemntal pressures < 30 mm Hg but high delta-p pressures have developed compartmental syndrome.

Myonecrosis following envenomation

Studies have shown that myonecrosis associated with compartmental syndrome after envenomation (release of toxic venom) is multifactorial and fasciotomy may not prevent myonecrosis. Myonecrosis is due to direct toxic effect of venom and inflammatory response. Thus patients should be aggressively treated with antivenom as it improves tissue perfusion.

Conclusions

Hyperbaric Oxygen Therapy (HBO)

This is a logical choice as it addresses the primary cause of ischemic injury. It reduces oedema by oxygen induced vasoconstriction while maintaining oxygen perfusion and thus supporting healing. HBO therapy protects against reperfusion injury. Studies show encouraging results with HBO. HBO improves wound healing, reduces amputation rate and declines the surgical procedure rate. It has been shown to be beneficial though it may not reverse the etiology of compartment syndrome.

Complications

These include:

  • Permanent nerve damage
  • Infection
  • Cosmetic deformity from fasciotomy
  • Limb loss
  • Death.

Patient education

The patient on discharge is told to follow up regularly and to come immediately if there is severe pain, numbness, burning sensation or weakness in the affected limb.

Lab studies

Arterial pressure index is useful in detecting major arterial injury. Systolic pressure in the affected limb is divided by the normal limb systolic pressure and if < 90% it is abnormal. The sensitivity of arterial pressure index ranges from 75 – 95% for injuries needing intervention. It is very sensitivity in ruling out popliteal artery injury in knee dislocations. Most injuries with pressure arerial index > 90% heal spontaneously.Ankle brachial index is also very sensitive. It is done by dividing the systolic ankle pulse on the affected leg with the arm (brachial) pressure on the same side.

Allen test is helpful brachial artery bifurcation injury. Here hand pallor persists by compression of the radial artery showing that the ulnar is injured and vice versa.

Imaging studies

Conventional angiography remains the gold standard for evaluating vascular injuries. The disadvantages are the high cost, time delay and a 0.6% major complication rate. Renal functions are a must before the study. Only I% of the patients with no hard signs have angiograms positive for intervention.

Colour Doppler studies have a 95% accuracy in diagnosing vascular injury without hard signs. It is of limited value in diagnosing poorly accessable vessels like subclavian, profunda femoris and profunda brachii arteries.

CT angiography – this has an accuracy of 95 – 100% for significant arterial injury. It is emerging as the choice for blunt trauma not needing surgical intervention right away.

Pre-hospital care

  • Stabilize limb in anatomic position
  • Control hemorrhage by pressure
  • Apply tourniquet if pressure is inadequate

Emergency department care

  • Immediately align fractured bones and dislocations if there is vascular compromise to prevent further injury to the neurovascular bundle.
  • Control hemorrhage by pressure but a tourniquet may have to be applied if pressure is inadequate.
  • After stabilizing the patient restore the circulation as soon as possible.
  • Do not apply clamps as this damages the arteries and surrounding tissue and makes repair more difficult.

Inpatient care

  • Surgical exploration and repair is done if there are hard signs or limb ischemia or refractory hypotension.
  • Patients with soft signs are further evaluated by CT angiography. High risk injuries like gunshot injuries without hard or soft signs need further evaluation with CT angiography. Low risk injuries without hard or soft signs must be observed. Major venous injuries must be repaired to prevent limb oedema, compartment syndrome and venous thrombosis.

Out-patient evaluation

  • Constant follow-up in patients with low risk injuries
  • Injuries with vascular repair are followed up for complications.

Complications

  • Delayed diagnosis may lead to thrombosis, embolization, and rupture with massive hemorrhage.
  • Risk factors for amputation include compartmental syndrome, arterial transaction, compound fracture and injuries above and below the elbow and knee.
  • Non occlusive injuries do not disrupt the flow and include the following:

1)      Pseudo-aneurysms – there may resolve completely or may compress the nerve over time or may rupture with              massive hemorrhage.

2)      Arterio-venous fistulae – may take months to mature and need closure surgically

3)      Intimal tears and flaps heal spontaneously over time

4)      Segmental narrowing may cause reduced flow but a feeble pulse is present. It may resolve spontaneously or                    need repair over time.

5)      10% patients with occult injuries need repair in 1 month. Rest 90% just need followup.

vein1

Skin graft over fasciotomy site

Prognosis

Most vascular without hard signs resolve over time. Long term follow-up with examination and investigations when necessary are adequate and an effective approach.

Patient education

Impress upon the patient the need for regular routine check-ups. Instruct them to come to the casualty if they have sudden pain, numbness, swelling, paresthesia or weakness in the concerned extremity or sudden bleeding.

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