tourniquet mgmc1
TRANSCRIPT
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Tourniquet
Dr S Parthasarathy MD DA DNB PhD Dip. software statistics FICA
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Definition
• A tourniquet is a constricting or compressing device used to control venous and arterial circulation to an extremity for a period of time.
• Venous
• Arterial !!
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History
• The word tourniquet itself derives from the French
verb tourner (to turn) and was first used by the
eighteenth-century French surgeon Louis Petit
describing the screw-like device he strapped to the
thighs of patients undergoing leg amputations, to
reduce blood loss.
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Taken from the internet for closed academic purpose only
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Esmarch
Pneumatic – microprocessor controlled Pneumatic manual
Petit original
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Indications
• Surgery • Trauma • "Hand surgery without tourniquet is like • repairing a clock in an ink container"
• For blood loss
• IVRA anesthesia and sympathectomy
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Contra indications
• Open fractures • Sickle cell disease • Plastic reconstructive surgery done • Sever hypertension • Compartment syndrome and compressions
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Types
• Emergency • Esmarch • Pneumatic • Microprocessor controlled
• Straight cuffs • Contour cuffs occlude the flow of blood at lower
pressures than straight cuffs that are of the same width
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Parts of tourniquet
• Inflatable cuff • Gas source ( nitrogen or air )• Pressure display • Pressure regulator ( within 2-6 mmHg) • Connection tubing
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Size
• 3 inches to 6 inches overlap
• Width more than half the diameter
• Tourniquets should be positioned on the limb at the
point of the maximum circumference.
• Soft padding – but no loose cotton
• The choice of size of tourniquet should allow
placement of two fingers between the cast padding
and the cuff
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Exsanguination
• Exsanguination before inflation of the tourniquet improves the
quality of the bloodless field and minimizes pain associated with
tourniquet use.
• It is normally done by limb elevation or using an elastic wrap of
the extremity.
• Malignancy, infection thrombi,fracture – simple elevation or
nothing – no wrapping
• Rapid inflation – veins and arteries simultaneous
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Exsanguination and inflation pressures
• Maximal exsanguination can be achieved by
elevation of the arm or leg for 5 min at 90◦and 45◦
respectively, without mechanical compression.
• 250 mmHg for upper limb and 300 for lower limb
• 100 and 150 above systolic for limbs – arbitrary
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Tourniquet Cuff Pressure• LOP can be defined as the minimum pressure
required to stop the flow of arterial blood into the
limb distal to the cuff.( limb occlusion pressure)
Not well defined Preop LOP
Safety in kids - ??
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Inflation or occlusion time
• One hour
• Not yet defined but may be up to three hours
• 10 minute deflation interval every one hour• Double tourniquet and cold extremities –
prolong • Pediatric patients – better less than 75 minutes
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Tourniquet related complications
Local Systemic
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Local
• Normal physiological conduction block in fifteen minutes
• Nerve injuries – 0.37% • 1 in 6200 • upper limb • 1 in 3700
Lower limb
• Edges of the cuff • Esmarch more – may be
1000 mm Hg • Radial N in Upper limb • Common peroneal N in
lower limb more affected
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Muscle injury
• Muscle injury tends to be greatest beneath the tourniquet because of the combination of ischaemia and mechanical deformation, and may persist after tourniquet deflation as a result of micro- vascular congestion
• Post tourniquet syndrome – weakness palsy without anesthesia
• Three weeks – usually normalize.
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Skin changes
• cutaneous abrasions, blisters and even pressure necrosis.
• The highest risk of skin injury occurs in: Children, obese, elderly, and patients with peripheral vascular disease
• Direct vascular injury is an uncommon complication of tourniquet use.
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Systemic effects- CVS
• Limb exsanguination and tourniquet inflation increase blood
volume and systemic vascular resistance that ultimately
cause a transient increase in central venous pressure
• Systolic BP and diastolic BP with heart rate rise
• 800 ml – exsanguinated sometimes
• How to decrease the rise in BP ?
• 0.25 mg/ kg of intravenous ketamine
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• After deflation , this may come back to cause hypotension
• Arrests after both lower limb deflation reported
• Reasons • Post ischemic reactive hyperemia • Anerobic metabolites
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Respiratory system • ETCO2 increase after deflation
• 1. 6 to 2.4 kpa
• This increase is due to the efflux of hypercapnic venous blood
from an ischaemic area into the systemic circulation, and an
increase in cardiac output following deflation of the tourniquet
• Spontaneous – 6n minutes – normal ,, controlled ventilation –
a little extra
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Cerebral
• Increased ETCO2 – increased cerebral blood flow in 2 minutes but comes back to normal in ten minutes
• Middle cerebra artery blood flow – 50 % rise • Patients where it matters – beware • Hyperventilate before deflation
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Hematological • Tourniquet inflation during surgery is associated with a global
hypercoagulable state.
• This is attributable to increased platelet aggregation caused by
catecholamines released in response to pain from surgery and the
tourniquet itself.
• Fibrinolysis after deflation - between - 15 – 30 minutes – may be
increased bleeding – increased tissue tpa release
• DVT no change if no tourniquet in TKR
• Release before wound closure- more blood loss.
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Excess bleeds intra op
• Common causes of intraoperative bleeding include
incomplete exsanguination of the limb and a poorly
fitting or under- pressurized cuff.
• Intraoperative bleeding may also be caused by blood
entering through the intramedullary vessels of long
bones.
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Temperature changes
• An increase in core body temperature occurs during
the inflation of arterial tourniquets because of
reduced metabolic heat transfer from the central
compartment to the peripheral compartment and
also from decreased heat loss from distal skin.
• Deflation can cause decrease -- – 0.5 – 1 degrees
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Metabolic changes
• On deflation --- Increased lactic acid, PaCO2,and potassium levels, and decreased levels of PaO2, and pH.
• Toxic metabolites produce pathophysiological changes when released into the general circulation.
• 30 minutes – becomes normal
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Pharmacology • We have isolated the limb • Does administration of some other drug influence • E.g we have applied tourniquet to both lower limbs – will
the dose of propofol change ?
• So far not studied , but relevance seems less.
• Intravenous antibiotics – possible 10 minutes prior to inflation
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Tourniquet pain
• Tissue compression – release of prostaglandins
• A fbres are blocked by mechanical compression
• Mostly “c” fibres
• NMDA agonism and central sensitization
• Dull aching poorly localized tight pain or discomfort
• Increased HR and BP ( touniquet hypertension)
• Difficult to prevent and treat this – even in spinal and dense blocks
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Tourniquet pain
• 45 minutes usual –• That’s pressure pain – touch sensation should go • Adjuncts – clonidine opioids , adrenaline bicarb • Local anesthetics at the cuff edge , EMLA • Intravenous ketamine, dexmed , remifentanyl, • Magsulf • Preemptive gabapentin • Conversion to GA • Deflate and reinflate
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Other effects
• Post op pain, edemas and infection increased if we do with tourniquet tibia plates and nails
• Ream with touniquet - ? Bone necrosis • femur fracture was treated by intramedullary nail,
tourniquet use for other lower limb fractures might increase pulmonary morbidity
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Summary
• History • Types • Pressure , time • Systemic changes • Local changes • Tourniquet pain