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aaa Emergency Med - Exam 2 > 29 - Compartment Syndrome > Flashcards

29 - Compartment Syndrome Flashcards

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1
Q

Objectives

A
  • Compartmental anatomy of the lower extremity (foot and lower leg)
  • Etiologies and pathophysiology of acute compartment syndrome
  • Diagnosis and management of acute compartment syndrome
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2
Q

Anatomic compartments of the leg (Hayden system ***)

A
  • Anterior
  • Lateral
  • Superficial posterior
  • Deep posterior
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3
Q

Anterior leg

A

o Tibialis anterior
o Extensor halluces longus
o Extensor digitorum longus
o Peroneus tertius

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4
Q

Lateral leg

A

o Peroneus longus

o Peroneus brevis

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5
Q

Superficial posterior leg

A

o Soleus
o Gastrocnemius
o Plantaris

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6
Q

Deep posterior leg

A

o Tibialis posterior
o Flexor hallucis longus
o Flexor digitorum longus

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7
Q

Anatomic compartments of the foot (Myerson system ***)

A

NOTE: This is the BEST classification system so MEMORIZE THIS

  • Central
  • Medial
  • Interosseous
  • Lateral
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8
Q

Central foot

A

o Flexor digitorum brevis
o Lumbricals
o QP
o Adductor halluces

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9
Q

Medial foot

A 
o	Abductor halluces 
o	Flexor halluces brevis 
o	Flexor halluces longus tendon 
o	Peroneus longus tendon 
o	Posterior tibial tendon
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10
Q

Interosseous

A

o Interosseous muscles

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11
Q

Lateral foot

A

o Abductor digiti minimi

o Flexor digiti minimi

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12
Q

Flexor stabilization (STANCE PHASE – MOST COMMON)

A

o Seen with flexible pes valgus, STJ pronation and MTJ supination (unlocked)
o FDL and FDB fire earlier and longer in order to attempt to stabilize the foot
o The flexors therefore overpower the interosseous muscles
o FDL and FDB insert at the bases of the distal and middle phalanges
o During the stance phase of gait, the flexors plantarflex the digits, causing dorsiflexion at the MPJ (reverse buckling)
o Interosseous muscles insert on the base of the proximal phalanx – they act to plantarflex the MPJ during stance phase, which balances the reverse buckling of the flexors
o Can be due to weak QP, more medial pull of long flexors, medial abduction

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13
Q

Flexor substitution (SWING PHASE)

A

o Weak triceps surae
o Deep posterior and lateral groups attempt to “substitute” for the lack of plantarflexory force
o The flexors therefore fire earlier and longer and therefore overpower the interosseous muscles
o Least common type, seen in supinated feet and tends to appear as straight contracture of all lesser toes

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14
Q

Extensor substitution (SWING PHASE)

A

o EDL acts to dorsiflex the MPJ (via tightening of the extensor sling and extended the IPJs during swing
o Lumbricals act to plantarflex the MPJ while also extending the IPJs (via extensor wing)
o Flexors have a passive pull on toes during swing
o Lumbricals counteract the dorsiflexion caused by the passive pull of the flexors and the EDL during swing
o Starts as a flexible deformity that reduces completely during weight bearing, but may become rigid

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15
Q

Manoli and Weber – DO NOT MEMORIZE THIS

A
  • Just another classification system

- Involves 9 compartments of the foot (one for each interossei muscle)

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16
Q

Clinical findings for acute compartment syndrome – KNOW FOR EXAM ***

A
  • Recalcitrant pain
  • Compartmental tenseness
  • Sensory deficits following nerve distribution
  • Motor deficits
  • Pain on passive stretch
17
Q

Compartmental pressure measurement – KNOW FOR EXAM ***

A
  • Wick catheter
  • Slit catheter
  • Injection
  • Infusion
  • Stryker system
18
Q

Compartment pressures – KNOW FOR EXAM ***

A
  • Normal resting pressure: 0-8 mmHg
  • Monitoring zone: 30-40 mmHg
  • Pathologic pressure: 40 mmHg in the presence of clinical symptoms
19
Q

Additional studies to consider doing ***

A
  • ECG
  • Urinalysis (routine and myoglobin analysis)
  • Blood work (CBC with diff, electrolytes, BUN/creatinine, creatinine kinase)
20
Q

Pathophysiology and causes of acute compartment syndrome ***

A
  • Bleeding and interstitial edema occur after injury
  • Compartmental interstitial pressures increase
  • Increases local venous pressure
  • Reduces local arteriovenous gradient
  • Collapse of veins and loss of blood flow
  • Results in microvascular compromise and myoneural damage
21
Q

Causes of compartment syndrome ***

A
  • Exertional
  • Trauma ***
  • Bleeding ***
  • Burns
  • Infiltration
  • Major vascular injury
  • Surgical closure ***
  • External pressure
  • Snake bites
  • Infection
22
Q

Study on surgical management ***

A
  • Matsen reported 91% of extremities decompressed 12 hours after clinical onset had neuromuscular deficits
  • Published principles of decompression
23
Q

Principles of decompression

A

o Foot: dorsal vs plantar medial vs lateral vs combined approach
o Leg: parafibular vs two incisional approach
o Intraoperative pressures
o Avoid use of tourniquet
o Minimal debridement of muscle
o Greater than two compartments involved, decompress all compartments

24
Q

Post-op management ***

A
  • Monitor compartmental pressures
  • Patman-Thompson technique
  • Splinting
  • Passive range of motion
  • Delayed closure or grafting
25
Q

Complications ***

A
  • Inadequate decompression
  • Volkmann’s contracture
  • Infection
  • Myoglobinuric renal failure
26
Q

Myerson study ***

A
  • 41% incidence of compartment syndrome
  • Highest incidence in Lisfrac and metatarsal injuries
  • 17% of calcaneal fractures were associated with a compartment syndrome
  • 13% of intraarticular calcaneal fractures had compartment measures greater than 30 mmHg
27
Q

Conclusions ***

A
  • Include compartment syndrome as a possible complication of foot injuries
  • Consider pressure measurements with injuries suggestive of compartment syndrome
  • Repair or close fascial borders with ORIF?
  • Need retrospective studies on injuries with greatest potential for compartment syndreom
  • Should we monitor elective foot cases?
28
Q

CASE STUDY

A

o 36-year-old female seen in the ED
o Was partying previous evening, much to drink
o Remembers something falling on her right foot
o Passed out
o Awoke this morning intense right foot pain

29
Q

Physical exam

A

o Swelling, tenseness of compartment
o Pulses are usually able to be heard, not palpable due to swelling
o Pain on passive stretch – pain out of proportion to what you would expect
o Nerve impingement leading to motor and sensory deficit
o Pain medication that does not work leads you to believe that the pain is “out of proportion”

30
Q

Most common reasons for acute compartment syndrome

A

o Crush injuries

o Acute embolic event

31
Q

Diagnostic tests - x-rays

A
  • Transverse fractures of 3rd and 4th bases, complete on 3rd metatarsal, incomplete on 4th metatarsal, nondisplaced.
  • Complete transverse fracture of 3rd metatarsal head, nondisplaced.
  • Transverse fractures are typically seen with blunt direct force (dropping something on foot), whereas a spiral/oblique is associated with a twisting force.
32
Q

Diagnostic tests - Compartmental pressures

A
  • Need to know anatomy in order to take these pressures

- Resting pressure is 0-8 mmHg

33
Q

Crush injury

A

o Crush injury typically has a higher level of inflammation than a twisting injury
o Leads to increased inflammation, hematoma formation, crush of bone leads to vascular leak – all leading to pressure increase
o Arteries function at higher pressure, so it could withstand more pressure before collapse
o Venous system is going to attempt to maintain blood flow, so it has the ability to adapt by increase in A/V gradient – ultimately you reach a point where the veins are overwhelmed and the veins shut down
o Eventually you will reach a pressure where the arterioles will shut down
o Venuoles affected first, then arterioles will eventually be effected
o When blood flow is restricted, muscles release myoglobin which is toxic to kidneys
o Check creatine kinase (up and coming gold standard) and BUN creatinine (for monitoring)

34
Q

Testing with a striker unit

A

o Compartmental pressure measurement
o Make small wheal of lidocaine subcutaneously
o Insert needle into compartment and test pressure

35
Q

PRESSURES

A

o Normal resting pressure: 0-8 mmHg
o Monitoring zone: 30-40 mmHg (if it includes all signs of compartment syndrome, need to act)
o Pathologic pressure: 40 mmHg in the presence of clinical signs (classic compartment syndrome)

36
Q

What else can cause compartment syndrome?

A

o Snake bite
o Deep space abscess
o Casting in acute swelling
o Anything that could expand the fluid in a compartment

37
Q

Management via decompression

A

o Myofascial release, fasciotomy
o Global compartment syndrome is managed by two dorsal incisions most commonly to release all 4 compartments
o There is another option to release all compartments medially
o Lightly pack the open wounds
o Foot looks better within 24 hours
o Anytime you have open wounds, always have them on prophylactic antibiotics
o Leave wounds open for 3 days, then leave fascia open
o When closing wounds, delayed primary closure, skin graft to get edges to close, or use wound vac – will need to do something to get the wounds closed
o New method could be to do high tension steri strips and drag edges closer and closer together then do a delayed primary closure

aaa Emergency Med - Exam 2 (9 decks)

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