compartment syndrome Flashcards
1
Q
Define compartment syndrome
A
- a constellation of symptoms and signs that result from elevated interstitial pressure in a fibro-osseous compartment that exceeds capillary pressure, resulting in microcirculatory –> macrocirculatory disturbance, and eventual muscle/nerve ischemia & fibrosis
2
Q
what is Volkmann’s ischemic contracture?
A
- it is the sequallae of untreated compartment syndrome, such that there is muscle fibrosis and contracture, nerve fibrotic compression and ischemia, and other soft tissue contracture (joints, overlying soft tissue)
3
Q
What is crush syndrome?
A
- a reperfusion injury that can occur during end-stage compartment syndrome, that includes systemic manifestations such as:
- rhabdomyolysis (skeletal muscle break down) –> acute kidney injury / failure
- electrolyte disturbances (skeletal muscle necrosis and release of Ca, K+) –> cardiac dysrhythmia
- third-spacing edema / fluid loss –> hypovolemia / hypovolemic shock
4
Q
What is an ischemia-reperfusion injury?
A
- process that can occur after reperfusion of previously ischemic tissue causing an acute inflammatory response and further tissue injury
Why?
- ischemic tissue had utilized all ATP and was undergoing anaerobic metablism, therefore presence of ATP by-products & lactate
- oxygen delivery to this tissue causes:
- release of oxygen free radicals (O2 + ATP break-down products, also release from inflammatory mediators like neutrophils)
- release of other pro-inflammatory mediators like thromboxane and leukotriene
- O2 free radicals, LT, TXA –> capillary permeability, endothelial damage, platelet aggregation –> worsening edema and thrombosis –> secondary ischemic insult
5
Q
What are risk factors for compartment syndrome?
A
- closed long bone fracture (tibia, 1-2%)
- open long bone fracture (tibia, 6-9%)
- young male
- high energy injury
- bleeding diathesis
- vascular injury
6
Q
What are some etiologies for compartment syndrome?
A
- Decreased compartment size
- Thermal burn, tight external dressing, clsoure of compartment
- Increased compartment “contents”
- Edema
- Arterial: injury, acute ischemia (thrombosis), spasm
- Iatrogenic: reperfusion of ischemic limb, replant
- Venous stasis
- Exercise-induced
- Envenomation
- Prolonged immobilization w/ compression /malposition: EtOH/drugs, GA
- Thermal injury, frostbite
- Hemorrhage
- vascular injury, bleeding diathesis
- Fracture + Edema + Blood
- closed/open fracture, orthopedic surgery
*
- closed/open fracture, orthopedic surgery
- Edema
7
Q
Describe pathophysiology of compartment syndrome
A
- increased intra-compartmental pressure to due some combination of decreased comparmental compliance and increased intra-compartmental “contents”
- In general, due to fibro-osseous barrier of compartment, there is little baseline compliance to permit excessive expansion to accommodate increasing pressure
- As interstitial pressure rises
- lymphatic channels close
- venous outflow pressure increases to accommodate, narrowing the arterial-venous gradient required for perfusion
- exceeds capillary perfusion pressure
- local tissue ischemia releases vasoactive and inflammatory substances like: histamine, NO, serotonin, thromboxane, leukotrienes
- further capillary permeability, endothelial damange, platelet aggregation
- worsens edema, leads to further thrombosis, secondary/progressing ischemia
- 2 theories - Matsen A-V gradient theory and ischemia-reperfusion theory each explain a component of above processes
8
Q
what are the cardinal signs of acute compartment syndrome?
A
- Pain - Persistent, Progressive, out of Proportion
- pain w/ Passive stretch is earliest finding
- Paresthesia - #2 sign
- Paralysis - #3 sign
- Pulselessness - late sign
- Palpably tense compartment - most subjective sign
9
Q
What investigations do you do for suspicious or suspected compartment sydnrome?
A
- if indeterminant, can measure compartment pressure
- Stryker needle
- using slit needle and arterial line set-up
- using needle manometer, 3-way stop-cock
- needle is perpendicular to compartment, measure ALL compartments, measure closest to injury
- labs for pre-operative work-up & screen for crush syndrome manifestations
- CBC, lytes/extended lytes, BUN, creatinine, lactate, CK, coags, group & screen
- Urine examination of colour (myoglobinuria), send myoglobin
- ECG
- XR for associated fracture; otherwise no imaging will contribute to diagnosis
10
Q
how do you interpret compartment pressure measurements in context of assessment for compartment sydnrome
A
- clinical suspicion/diagnosis is clear and sufficient to make deicsion for operative open fasciotomy
- if uncertain, then generally compartment pressure of > 30mmHg is sufficient for diagnosis
- if known time of onset and clinically suspicion is low or indeterminant, can reduce fracture, loosely splint, elevate to heart and observe serially
- alternatively, pressure differential (delta-p) between diastolic pressure and measured compartment pressure
- if < 30mmHg then fasciotomy
11
Q
which patients do ou consider a prophylactic fasciotomy?
A
- limb revascularization (s/p trauma or thrombus), especially if ischemia time > 6 hrs
- gustillo 3B/3C open tibial fracture
- major crush injury
- electrical injury
12
Q
What do you do when a patient presents w compartment syndrome for > 48 hrs? (delayed recognition or presentation)
A
- Controversial
- if ongoing pain, then likely still some functional muscle, strongly consider fasciotomy
- if no evidence of muscle function, may not derive benefit from fasciotomy (however there may be a benefit to nerve decompression even in this scenario)
- major disadvantage when low suspicion of much remaining viable muscle, is taking STERILE ischemic & developing fibrotic tissues and exposing to non-sterile field, risking local/disseminated infection, sepsis, amputation
13
Q
What are complications or sequellae of a compartment syndrome (even when recognized and treated)
A
- Muscle tolerates < 4 hrs warm ischemia, therefore some ischemia @ 6 hrs, profound and irreversible ischemia @ 8 hrs
- lead to atrophy, fibrosis, contracture/shortening
- associated joint, other soft tissue contracture, adhesions, weakness, decreased ROM
- soft tissue manifestations (blister, wound) – scar, contracture
- nerve ischemia, compression, fibrosis, contracture; hypo/hyperesthesia, chronic motor weakness
- amputation
- crush syndrome
- volkmann’s ischemic contracture
14
Q
what is chronic compartment syndrome
A
- exercise induced / exertional compartment syndrome, that occurs when intracompartmental pressures increase periodically during intense exercise, resulting in relative decreased tissue perfusion and ischemic type pain
- characterized by exertional ischemic pain that is often relieved by rest, history may indicate that these symptoms are worsening over time, bilateral complaints
- physical exam often has minimal findings; possibly distal paresthesia or mild weakness
- investigations at rest may not reveal anything; ideally will take pre-exertion, during exertion and post-exertional compartment pressure assessments
15
Q
What are the principles of fasciotomy for compartment syndrome?
A
- Incision design:
- curvilinear, no straight lines across joints
- skin flaps to cover vital structures (ie NV bundles)
- avoid injury to superficial nerves and large veins
- aim for decompression of known points of compression/spaces (carpal tunnel)
- release all involved/potentailly involved compartments and individual muscles, superficial and especially deep
- consider epimysiotomy for especially tense or ischemic muscles
