Tourniquets
Complications
Systemic
Exsanguination
Embolisation risk (DVT, septic or tumour material)
Increased central volume and increased SVR (increased BP and CVP)
During its application
Tourniquet failure intra op
Bleeding if anterograde flow is not reduced and VR is obstructed
Tourniquet pain from one hour after inflation (increased HR and BP) - mediated by C fibres
Deflation
Blood volume shifts and release of anaerobic metabolites (lactate, K+) and CO2 causes metabolic and haemodynamic changes - myocard depression, reduced SVR and MAP, reduced CVP.
Bleeding
Embolisation risk (air, fat, cement)
Localised
Nerve and muscle injury
Poor application technique
Mechanical pressure (nerve), ischaemia (muscle)
Skin injury
Poor application technique
Moisture under padding
Microvascular injury
Post tourniquet syndrome (oedematous, pale, stiff limb with weakness but no paralysis)
Minimisation of complications
CI to tourniquet use
AV fistulas
PVD - risk damage to atheromatous vessels, causing fracture of plaque
DVT
Sickle cell disease
Poor skin integrity
Peripheral neuropathy
Cuff
Widest possible
20% greater than diameter of arm (enables lower inflation pressure for arterial occlusion (Force = inflation pressure x area beneath cuff)
Curved cuffs designed to fit conical parts of limbs (allow lower inflation pressures)
Where nerves are protected by overlying muscle
Regular maintenance
Skin protection
Ensure not pinched by tourniquet
Soft padding under tourniquet before inflation
Limb exsanguination
Prior to application of tourniquet
Time and pressure
Time
Short duration (max 2hrs)
Breaks for reperfusion if req after this time (10mins)
Pressure
Should have a relationship to the SBP (e.g. 50-100mmHg greater) to reduce anterograde flow
Maximal pressures are controversial
Normally 200mmHg is adequate for the UL and 250mmHg for LL (increase if atherosclerosis or morbid obesity)
Audiovisual time and pressure alarms
High and low pressure alarms
Tourniquet deflation
Anticipation with fluid bolus
Use of vasopressors
Hyperventilation
Vigilance for arrhythmia and MI
Tourniquet pain
Difficult to manage
Resistant to anaesthesia and analgesia
Only effective method is temp tourniquet release