Tourniquet (Anaesthesia Exam Answer - 5 Marks)

• Pneumatic cuff tourniquet (most common) - single or double cuff
• Esmarch bandage (elastic exsanguination bandage)
• Automatic tourniquet systems with pressure/time alarms

• Limb surgery requiring a bloodless field (orthopedic, hand, vascular repair)
• Intravenous regional anesthesia (Bier's block)
• Control of hemorrhage (trauma/emergency)

• Limb elevated and exsanguinated (Esmarch bandage) before inflation
• Cuff placed proximally, padded to avoid skin injury; antiseptic solution must not pool under the cuff (risk of chemical burn)
• Inflation pressure: upper limb ~50-75 mmHg above systolic BP (or limb occlusion pressure, LOP); lower limb ~90-150 mmHg above SBP
• Tourniquet time recorded; safe limit ~2 hours in a healthy adult; reperfusion interval of 10-15 minutes recommended if prolonged surgery requires re-inflation

• Progressive sympathetic activation - tourniquet pain (dull, aching, burning), hypertension, tachycardia, diaphoresis - typically after 30-60 minutes, occurs even under regional/general anesthesia due to unmyelinated C-fiber conduction that resists neuraxial blockade
• Local ischemia, hypoxia, and metabolic acidosis distal to cuff
• Increased intracranial and intraocular pressure with prolonged inflation

• Sudden decrease in systemic vascular resistance -> transient hypotension and reflex tachycardia
• Washout of accumulated anaerobic metabolites (lactate, CO2, potassium) into circulation -> transient systemic metabolic acidosis and rise in ETCO2/PaCO2
• Immediate relief of tourniquet pain and hypertension
• Core temperature may fall (cool blood returning from ischemic limb)
• Risk of pulmonary embolism (rare, from dislodged thrombus after limb exsanguination/ischemia)

• Tourniquet pain and hypertension
• Nerve injury/palsy (ischemia + mechanical compression - e.g., radial nerve palsy)
• Skin injury, chemical burns (pooled antiseptic), bruising
• Muscle ischemia, rhabdomyolysis, compartment syndrome
• Post-tourniquet syndrome (stiffness, pallor, weakness)
• Metabolic acidosis, hyperkalemia on release
• Pulmonary embolism (rare but reported fatal cases)
• Vascular injury in patients with calcified/atherosclerotic vessels

• Regional techniques (spinal/epidural) reduce but do not abolish tourniquet pain; adding opioids to neuraxial block helps
• For prolonged procedures under regional block, general anesthesia or supplemental sedation/analgesia may be required once tourniquet pain sets in
• Monitor blood pressure and heart rate closely around inflation and deflation
• Anticipate and prepare for hemodynamic changes at deflation (hypotension, rise in ETCO2)
• Avoid tourniquets in patients with sickle cell disease, severe peripheral vascular disease, or limb infection

• Severe peripheral vascular disease
• Sickle cell disease/trait
• Deep vein thrombosis in the limb
• Severe crush injury or limb infection