Crush Injuries Flashcards
What is the definition of crush injury?
A direct injury resulting from crush
what is the definition of crush syndrome?
The clinical condition caused by compression of muscle with subsequent rhambdomyalosis which can cause the complications of electrolyte disturbances, fluid sequestration and myoglobinuria
What are the causes of crush injury syndrome?
Severe crush injuries
I-mobile on rigid surface from more than an hour
CO poisoning, stroke, head trauma, elderly hip fracture, Serve assault
How long can stated muscles remain ischemic?
Up to four hours
If there is a combination of mechanical forces and ischemia how long would it take for muscle death to occur?
One hour
What are the pathophysiological steps involved in crush syndrome?
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
What is myoglobin?
Iron-oxygen binding protein found in muscle tissue which assists mammals to hold their breath longer
What is myoglobinuria?
hen myoglobin is present in the urine. This only occurs after muscle injury
What effect does myglobinuria have on the body?
Myoglobin precitate and block renal tubular flow
- Increases viscosity and acidity of the blood
Directly toxic to renal tubular cells
What are some of the things that may cause Rhabdomyolysis?
Trauma/crush Drug use- cocaine, speed, heroin Extreme muscle exertion Medications - statins Prolonged muscle pressure on hard surface High body temp/heat stroke
What is Rhabdomyolysis?
Breakdown of muscle fibres that leads to the release of muscle fibre contents into the bloodstream
What are the clinical features of Rhabdomyolysis?
Abnormal dark urine (cola coloured) Decreased urine output general weakness muscle stifness muscle tenderness weakness of affected muscles Fatigue, joint pain, seizures
What sings on the ECG would suggest hyperkalamia?
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
What is the definition of compartment syndrome?
When high pressure build up in a closed fascia space
What causes compartment syndorme?
Capilary blood perfusion is decreased which prevents adequate circulation to necessary areas and compromises tissue viability.
What are the different types of limb compartment syndrome?
Acute
Chronic
Crush
What is acute limb compartment syndrome?
Raised pressure within a closed limb (lower leg/forearm)
what are some of the things that cause limb compartment syndrome?
Orthopaedic- fractures Vascular/iatrogenic (medical procedure) Extraversion- leakage of fluid into compartment Soft tissue injuries- Crush/burns Hypotension will worsen all causes
What is the incidence range for compartment syndrome post tibia fracture?
1.5-29%
How does compartment syndrome evolve after initial damage?
- 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
Clinical features of compartment syndrome?
palpably swallow pain on passive strech progressive pain altered sensation Pain out of proportion to injury weakness (late) progression over short period of time
How long would it take for irreversible muscle and nerve damage to occur after compartment syndrome?
Muscles- 6 hours
Nerves 4 hours
What is normal compartment pressure? At what pressure is muscle isceamia produced?
<15 might normally
at >30mmhg muscle isechmia is produced
What is the issue with re-perfusion after crush injuries?
Tissue destruction and prolonged hypoxia creates toxic substances that when re-perfused are realised into the blood stream. Hyperaemia is a big issue
What is the logic behind applying a tourniquet to crushed limbs?
Prolongs repercussion so that it can happen in a more controlled hospital setting where hyperkalemia can be managed better.
what causes suspension trauma?
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
What are some expected sings of suspension trauma?
Decreased BP, Tachycardia, fainting, heart palpitations, sweating and nausea
What is the management for crush injuries?
Remove harness if possible Lay patient in vertical position 20/ml kg aliquot of saline Sodium bicarbonate if possible Tourniquets where possible to limbs
