Tourniquet mgmc1

Tourniquet

Dr S Parthasarathy MD DA DNB PhD Dip. software statistics FICA

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 !!

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.

Taken from the internet for closed academic purpose only

Esmarch

Pneumatic – microprocessor controlled Pneumatic manual

Petit original

Indications

• Surgery • Trauma • "Hand surgery without tourniquet is like • repairing a clock in an ink container"

• For blood loss

• IVRA anesthesia and sympathectomy

Contra indications

• Open fractures • Sickle cell disease • Plastic reconstructive surgery done • Sever hypertension • Compartment syndrome and compressions

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

Parts of tourniquet

• Inflatable cuff • Gas source ( nitrogen or air )• Pressure display • Pressure regulator ( within 2-6 mmHg) • Connection tubing

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

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

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

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 - ??

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

Tourniquet related complications

Local Systemic

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

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.

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.

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

• After deflation , this may come back to cause hypotension

• Arrests after both lower limb deflation reported

• Reasons • Post ischemic reactive hyperemia • Anerobic metabolites

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

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

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.

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.

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

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

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

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

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

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

Summary

• History • Types • Pressure , time • Systemic changes • Local changes • Tourniquet pain