Crush Injuries

Question 1

What is the definition of crush injury?

Answer 1

A direct injury resulting from crush

Question 2

what is the definition of crush syndrome?

Answer 2

The clinical condition caused by compression of muscle with subsequent rhambdomyalosis which can cause the complications of electrolyte disturbances, fluid sequestration and myoglobinuria

Question 3

What are the causes of crush injury syndrome?

Answer 3

Severe crush injuries
I-mobile on rigid surface from more than an hour
CO poisoning, stroke, head trauma, elderly hip fracture, Serve assault

Question 4

How long can stated muscles remain ischemic?

Answer 4

Up to four hours

Question 5

If there is a combination of mechanical forces and ischemia how long would it take for muscle death to occur?

Answer 5

One hour

Question 6

What are the pathophysiological steps involved in crush syndrome?

Answer 6

Breakdown of myocyte cells membranes
Sarcolemma permeability increases
Influx Na, H2O, and Ca into sarcoplasm
Cellular swelling, increased Ca, disruption of function/respiration, decreased ATP, myocytoic death

Question 7

What is myoglobin?

Answer 7

Iron-oxygen binding protein found in muscle tissue which assists mammals to hold their breath longer

Question 8

What is myoglobinuria?

Answer 8

hen myoglobin is present in the urine. This only occurs after muscle injury

Question 9

What effect does myglobinuria have on the body?

Answer 9

Myoglobin precitate and block renal tubular flow
- Increases viscosity and acidity of the blood
Directly toxic to renal tubular cells

Question 10

What are some of the things that may cause Rhabdomyolysis?

Answer 10

Trauma/crush 
Drug use- cocaine, speed, heroin
Extreme muscle exertion
Medications - statins 
Prolonged muscle pressure on hard surface
High body temp/heat stroke

Question 11

What is Rhabdomyolysis?

Answer 11

Breakdown of muscle fibres that leads to the release of muscle fibre contents into the bloodstream

Question 12

What are the clinical features of Rhabdomyolysis?

Answer 12

Abnormal dark urine (cola coloured)
Decreased urine output 
general weakness
muscle stifness
muscle tenderness
weakness of affected muscles
Fatigue, joint pain, seizures

Question 13

What sings on the ECG would suggest hyperkalamia?

Answer 13

Peaked T waves 
Widening QRS
shortened QT interval and sometimes ST segment depression 
Reduced amplitude of p waves 
rhythm eventual go to sine wave pattern

Question 14

What is the definition of compartment syndrome?

Answer 14

When high pressure build up in a closed fascia space

Question 15

What causes compartment syndorme?

Answer 15

Capilary blood perfusion is decreased which prevents adequate circulation to necessary areas and compromises tissue viability.

Question 16

What are the different types of limb compartment syndrome?

Answer 16

Acute
Chronic
Crush

Question 17

What is acute limb compartment syndrome?

Answer 17

Raised pressure within a closed limb (lower leg/forearm)

Question 18

what are some of the things that cause limb compartment syndrome?

Answer 18

Orthopaedic- fractures
Vascular/iatrogenic (medical procedure)
Extraversion- leakage of fluid into compartment 
Soft tissue injuries- Crush/burns
Hypotension will worsen all causes

Question 19

What is the incidence range for compartment syndrome post tibia fracture?

Answer 19

1.5-29%

Question 20

How does compartment syndrome evolve after initial damage?

Answer 20

• Initial oedema/heammorage/external compression
• Issue with Venus return
• Raised compartment pressure causes compression of -small venules
• Worsening oedema and pressure
• Arteriol compression
• Muscle and nerve ischemia

Question 21

Clinical features of compartment syndrome?

Answer 21

palpably swallow 
pain on passive strech
progressive pain 
altered sensation 
Pain out of proportion to injury 
weakness (late)
progression over short period of time

Question 22

How long would it take for irreversible muscle and nerve damage to occur after compartment syndrome?

Answer 22

Muscles- 6 hours

Nerves 4 hours

Question 23

What is normal compartment pressure? At what pressure is muscle isceamia produced?

Answer 23

<15 might normally

at >30mmhg muscle isechmia is produced

Question 24

What is the issue with re-perfusion after crush injuries?

Answer 24

Tissue destruction and prolonged hypoxia creates toxic substances that when re-perfused are realised into the blood stream. Hyperaemia is a big issue

Question 25

What is the logic behind applying a tourniquet to crushed limbs?

Answer 25

Prolongs repercussion so that it can happen in a more controlled hospital setting where hyperkalemia can be managed better.

Question 26

what causes suspension trauma?

Answer 26

vertical position leads to venous pooling, immobility leads to more venous pooling as muscle pump isn’t used. There can be compression on femoral arteries
Loss of cerebral perfusion and consciousness

Question 27

What are some expected sings of suspension trauma?

Answer 27

Decreased BP, Tachycardia, fainting, heart palpitations, sweating and nausea

Question 28

What is the management for crush injuries?

Answer 28

Remove harness if possible 
Lay patient in vertical position 
20/ml kg aliquot of saline 
Sodium bicarbonate if possible 
Tourniquets where possible to limbs