Pneumatic Tourniquets

Components and Equipment

• Cuff - an inner inflatable bladder fully enclosed in an outer casing (to prevent "blowout" and pressure loss)
• Pressure source - compressed gas cylinder or wall supply
• Pressure gauge/regulator - aneroid or digital; must be calibrated frequently (discrepancy >20 mm Hg requires repair/replacement; gauges have been found to be up to 300 mm Hg off calibration)
• Alarm system - modern automatic units self-test on startup

Application Technique

1. Padding: Apply at least two layers of orthopaedic wool/felt (e.g., Webril) smoothly around the limb. Wrinkles must be avoided - they can cause blisters, skin pinching, and necrosis.
2. Application site: Upper arm (near axilla) for the upper limb; mid/upper thigh for the lower limb. A well-padded proximal calf tourniquet is safe for foot and ankle surgery.
3. Exsanguination: Elevate the limb for 2-5 minutes, or wrap with a 10 cm elastic bandage from the fingertips proximally just distal to the tourniquet.
4. Inflation: Inflate to the appropriate pressure (see below).
5. Skin preparation precaution: Apply a circumferential adhesive-backed plastic drape just distal to the tourniquet to prevent prep solutions from running underneath - otherwise chemical burns can result.

• Campbell's Operative Orthopaedics 15th Ed 2026

Cuff Selection

• Wide cuffs are more effective at lower inflation pressures than narrow ones
• Curved (contoured) cuffs fit conical extremities better and require significantly lower arterial occlusion pressures than straight (rectangular) cuffs
• Straight tourniquets on conical thighs should be avoided, especially in muscular or obese individuals (risk of skin slough at the upper margin, particularly in the gluteal fold region)
• Recommended widths: 10 cm for the arm; 15 cm or wider for the leg

Pressure Guidelines

Duration and Timing

• General maximum: 2 hours (absolute maximum 3 hours; recovery takes 5-7 days)
• Tourniquet >90 minutes is a risk factor for wound healing complications in elective foot and ankle surgery
• For longer procedures (anticipated >2.5 hours): employ a 10-minute deflation interval every hour, then consider reducing pressure to 50-75 mm Hg above LOP

Contraindications and Cautions

• Compromised limb vascularity (peripheral vascular disease, questionable blood supply to the foot)
• Severe infections (may spread organisms proximally)
• Sickle cell disease (sickling risk under ischemia)
• DVT (risk of embolization)
• Severe hypertension (difficult to achieve adequate occlusion)
• Use with caution in diabetic neuropathy, severe atherosclerosis, and in patients on anticoagulants

Complications

• Campbell's Operative Orthopaedics 15th Ed 2026

Forearm Tourniquet (Alternative to Upper Arm)

• Allows the local anesthetic dose to be reduced to almost half that required with an upper arm tourniquet
• Lower frequency and severity of tourniquet pain (especially for procedures <25 minutes, or distal to the wrist with regional block)
• Associated with longer sensory block and prolonged postoperative analgesia

Ten Rules of Pneumatic Tourniquet Use (Braithwaite & Klenerman's Modification of Bruner's Rules)

• Campbell's Operative Orthopaedics 15th Ed 2026, Table 2.6

Advantage Over Esmarch Tourniquet

Key principle: The greatest danger in tourniquet use is an improperly calibrated gauge - gauges have been found to be 300 mm Hg off calibration in documented tourniquet injuries. Routine calibration is non-negotiable.

Pneumatic Tourniquets - Miller's Anesthesia 10e (2-Volume Set)

Purpose and Basic Settings

• Reduce intraoperative blood loss
• Provide a bloodless field (e.g., for cement fixation in TKA)

• Miller's Anesthesia 10e, Hip and Knee Arthroplasties

Haemodynamic Effects

On Inflation

• Blood from the exsanguinated limb is "autotransfused" centrally - raises preload transiently
• MAP and SVR may rise

On Deflation (clinically important)

• Mean arterial blood pressure drops significantly after tourniquet release
• Two mechanisms:
  1. Release of metabolites from the ischemic limb into systemic circulation
  2. Decrease in peripheral vascular resistance as the limb reperfuses
• In prolonged cases, the ischemic limb accumulates lactate, CO2, K⁺, and acid - release causes a sudden metabolic acidaemia
• In replantation surgery, lactic acidosis from prolonged tourniquet time is particularly problematic in patients with underlying lung disease; controlled ventilation is advisable to compensate for metabolic acidosis
• Miller's Anesthesia 10e, Hip and Knee Arthroplasties; Extremity Replantation

Tourniquet Pain

• Tourniquet pain typically begins after 60 minutes of inflation
• It occurs even in the presence of a regional anaesthetic that is adequate for the surgery
• Mechanism: caused by unblocking of unmyelinated C-fibres during recession of a neuraxial block (C-fibres are more resistant to local anaesthetic block than A-delta fibres and persist longer)
• Management:
  • Addition of opioids to spinal or epidural anaesthesia may ameliorate tourniquet pain
  • Blocking T2 dermatome helps decrease tourniquet pain in shoulder/elbow surgery (where the tourniquet sits on the upper arm)
  • Dual-cuff technique (for IVRA/Bier block): a second tourniquet is placed distal to the first; inflated 15 minutes after the proximal cuff, then the proximal cuff is deflated - the distal cuff now sits over anaesthetised skin, reducing tourniquet pain
• Miller's Anesthesia 10e, Hip and Knee Arthroplasties; Hand Surgery; Shoulder and Elbow Surgery

Nerve Injury from Tourniquet

• When prolonged tourniquet inflations are required, deflating the tourniquet for 30 minutes of reperfusion may reduce neural ischemia before re-inflation

Post-Deflation Bleeding

• Bleeding begins immediately on deflation and can continue for the next 24 hours
• This must be factored into fluid and transfusion management

Intravenous Regional Anaesthesia (Bier Block) - Tourniquet Protocol

1. Exsanguinate the arm with an elastic bandage (Esmarch)
2. Inflate the upper arm tourniquet to 50-100 mm Hg above systolic (often to 250 mm Hg)
3. Inject preservative-free local anaesthetic (lidocaine; prilocaine preferred in UK/Europe for its high therapeutic index) into a hand vein
4. Onset: approximately 6-8 minutes
5. Apply second (distal) cuff 15 minutes later, inflate it, then deflate the proximal cuff - reduces tourniquet pain by positioning the active cuff over anaesthetised skin
6. Do not deflate before 30 minutes - risk of LAST (systemic local anaesthetic toxicity) from bulk drug release into circulation
7. Adjuvants (ketorolac, clonidine, dexamethasone, dexmedetomidine) can reduce tourniquet pain and improve block quality, though routine use of ketorolac is now controversial

Key safety point: Complications occur when the tourniquet fails during initial injection or if deflated too early (<30 minutes), both of which risk LAST.

• Miller's Anesthesia 10e, Hand Surgery; Intravenous Regional Anaesthesia

Contraindication - Specific Patient Populations

• Miller's Anesthesia 10e

Foot and Ankle Surgery

• Thigh or leg tourniquets commonly used to limit blood loss
• Regional anaesthesia combining sciatic + femoral nerve blocks is sufficient for all procedures below the knee that do not require a thigh tourniquet
• If a thigh tourniquet is needed, the femoral nerve territory must also be blocked

Summary - Key Anaesthetic Points

• Miller's Anesthesia, 2-Volume Set, 10th Edition (2023)