The document discusses anesthetic concerns regarding tourniquet application. It covers the components and use of pneumatic tourniquets, including cuff selection and inflation pressure. Physiological effects of tourniquets are also reviewed, such as local and systemic impacts. Potential complications are outlined. Tourniquet pain mechanisms and management are described. Contraindications for tourniquet use focus on vascular conditions.

1. Anesthetic concerns of tourniquet application
Dr. Muhammed Alif

2. Introduction
● Device which is used to control the flow of blood to and/or from an extremity.
● The word ‘’tourniquet’’ from the French verb ‘’tourner’’ (to turn).
● Louis Petit used screw-like device strapped to the thighs of patients undergoing leg
amputations.
● Arterial tourniquet – usually a pneumatic device consisting of an inflatable cuff connected to a
compressed gas supply.
● Allow controlled arterial compression and distal circulatory stasis.
● Most common – in surgical procedures on the extremities, creates bloodless surgical field.
● Examples include joint replacements and the repair of tendons, nerves, and blood vessels.
● Also used in Bier’s block

3. Components of pneumatic tourniquets
Five basic components
● An inflatable cuff (bladder)
● Compressed gas source
● Pressure display
● Pressure regulator
● Connection tubing.

4. Inflatable cuff
● Pressure – exerted on the circumference of extremity
● Different types of cuffs available
Following criteria considered while selecting a cuff:
• Cuff location
• Single vs double bladder design
• Cuff shape
• Cuff length
• Cuff width
• Disposable vs reusable
• Specialty application
• Limb protection

5. ● Length and width of the cuff – individualized considering the size and circumference of the pt’s
limb
● Cuff should overlap 3 inches but not more than 6 inches
● Too much overlap - ↑ pressure and rolling or wrinkling of underlying soft tissue
● Too small – compromise effective inflation, unexpected release or inadequate constriction
● Width of the cuff – wider than half the limb’s diameter.
● Wider cuff minimize the risk of injury to underlying tissue by dispersing pressure over a great
area.
● Wider cuff – consistently occlude the blood flow at lower pressure in adults and children
● Placed at point of the maximum circumference
● Soft padding kept around the limb – reduce wrinkling pinching, shearing of the tissues.
● Cuff tubing – positioned on or near the lateral aspect of the extremity to avoid pressure on
nerves and kinking of the tubing.

6. Tourniquet cuff pressure
● Depends on number of variables: age, skin, blood pressure, shape and size of
the extremity, dimensions of the cuff
● Optimal inflation pressure not established.
● Recommends cuff pressure of 200 – 300 mmHg
Various methods implemented to lower effective cuff pressure:
 Double tourniquet technique to change the point of compression
 Controlled hypotension to bring down the SBP
 Doppler technique and pulse oximetry to confirm the absence of arteria pulse
 Tourniquet inflation based on limb occlusion pressure
 Cuff pressure synchronization with systolic BP.

7. Limb occlusion pressure
● Minimum pressure required to stop the flow of arterial blood into the limb distal to the cuff.
● Determined by gradually increasing tourniquet pressure until distal blood flow interrupted
● Association of Perioperative Registered Nurses guideline:
● Cuff pressure should be adjusted by adding safety margin to LOP
1. Add 40 mmHg for LOP < 130mmHg
2. Add 60 mmHg for LOP 131 -190 mmHg
3. Add 80 mmHg for LOP >190 mmHg
4. For paediatric, adding 50 mmHg recommended
● LOP – should be measured during preop check up or when BP stabilized after induction
● Best practice – cuff pressure according to pt’s SBP or LOP.

8. ● Exsanguination before inflation – improves quality of bloodless surgical field
minimizes pain due to tourniquet
● Normally done by limb elevation or by elastic wrap around the limb.
● Elastic wrap should not be used in:
infection, malignant tumour, thrombi in extremity
● Exsanguination is done by limb elevation alone
● Exsanguination and tourniquet use – controversial in sickle cell disease

9. Inflation or occlusion time
● Kept minimum to minimize risk to the patient
● Safe inflation time – not been accurately determined
● Varies with patient’s age, physical status, vascular supply to extremity
● Safe time limit of 1-3 hours – described
● Recommended to assess the operative situation at 2 hours
● If anticipated >2.5 hours, deflation for 10 mins, and at subsequent 1 hr interval
● Pediatric patients inflation time <75 mins – recommended for lower extremities

10. Cuff deflation:
● Causes release of anaerobic metabolites into the systemic circulation
● Cause hypotension, metabolic acidosis, hyperkalemia, myoglobulinemia,
myoglobinuria and possible renal failure.
● Known as myonephropathic metabolic syndrome
● Depends on size of the extremity, duration of tourniquet time, overall
physiological status of the patient.

11. Physiological effects of tourniquet application
Local effects
● Result of tissue ischemia distal to the inflated tourniquet and a combination of ischemia and
compression of the tissues beneath it.
Muscle
● Progressive decrease in Po2 and an increase in Pco2 within muscle cells.
● Energy stores steadily decline with time and intracellular stores of ATP and creatine phosphate are
exhausted after 2 and 3 h, respectively.
● Lactate concentration increases with the switch to anaerobic metabolism
● Changes to the histological appearances of muscle fibres - Marked changes in mitochondrial
morphology are visible after 1 h.
● Muscle underlying the tourniquet  subjected to both ischemia and compression
● Prone to develop changes such as local fibre necrosis after inflation times as short as 2 h.
● Microvascular injury occurs in muscle after ischaemia of greater than 2 h duration.

12. ● After tourniquet release  increased vascular permeability results in:
Interstitial and intracellular oedema  frequently leads to the ‘post
tourniquet syndrome’,
Patient has a swollen, pale, stiff limb with weakness but no paralysis.
Typically lasts 1–6 weeks.
Nerve
● Physiological conduction block develops between 15 and 45 min
● Conduction block affects both motor and sensory modalities
● Reversible after deflation of the cuff
● Rate of development of this conduction block is the same with cuff pressures of 150 and 300
mm Hg.
● suggests – ischaemia rather than direct compression is the cause

13. ● Direct mechanical compression of nerves  responsible for a second, longer lasting nerve
conduction block called ‘tourniquet paralysis’.
● Higher cuff pressures (e.g. 1000 mm Hg maintained for >1 h) can cause morphological changes
within the larger myelinated nerves
● Most marked at the sites where the pressure gradient between compressed and
uncompressed nerve is greatest
● At the proximal and distal edges of the tourniquet.
● The pressure gradient  results in displacement of the nodes of Ranvier, stretching and
degeneration of paranodal myelin and impaired nerve conduction
● Lasts up to 6 months.

14. Systemic effects
Cardiovascular effects
● ↑ in systemic vascular resistance and an effective ↑ in circulating blood volume – after exsanguination
and tourniquet inflation
● Transient ↑ in CVP and SBP
● b/l thigh tourniquet – can ↑ effective circulating blood volume by 15% (~750mL in adult)
● ↑ in CVP and circulatory overload
● Cardiac failure and cardiac arrest have been reported after the application of bilateral thigh
tourniquets.
● ↑ BP after transient rise  tourniquet pain –
● The rise in arterial pressure can be attenuated by the addition of ketamine (0.25 mg/kg)
● This may also help with tourniquet pain.

15. Tourniquet deflation,
● Post-ischaemic reactive hyperaemia is seen.
● Causes a transient increase in the volume of blood in the limb compared
with baseline levels.
● Metabolites from the ischaemic limb are released into the systemic
circulation.
● In combination with the redistribution of blood flow  causes a decrease
in both central venous and systolic pressures
● Temporary but can be dramatic.

16. Respiratory effects
● Deflation of the tourniquet  increase in end-tidal carbon dioxide concentration which usually peaks
within 1 min.
● The increase in Etco2 occurs for two reasons:
○ mixed venous PCO2 increases (after release of hypercapnic blood from the ischaemic area distal to the tourniquet into the
systemic circulation)
○ cardiac output increases after tourniquet deflation (in response to the decrease in arterial pressure).
● The peak increase in Etco2 concentration is greater with deflation of lower limb tourniquets (0.7–2.4
kPa) than with upper limb tourniquets (0.1–1.6 kPa).
● The duration of the increase in Etco2 depends on the ventilatory characteristics of the patient.
● In spontaneously breathing patients, minute ventilation increases rapidly  Etco2 returns to baseline
values within 3–5 min.
● In patients undergoing controlled ventilation, the Etco2 will typically remain raised for >6 min unless
minute ventilation is deliberately increased.

17. Central nervous system effects
● The increase in PaCO2 after deflation of the tourniquet causes an
increase in cerebral blood flow.
● Measurements of middle cerebral artery blood flow velocity show an
increase of up to 50%.
● In patients with head injuries  can cause an increase in intracranial
pressure.
● Hyperventilation after tourniquet deflation can prevent increases in
intracranial pressure by maintaining normocapnia.

18. Temperature effects
● Inflation of arterial tourniquets  associated with a gradual increase in
core body temperature.
● Caused by reduced heat transfer to and heat loss from the ischaemic
limb.
● The magnitude of this increase is small, ~0.5oC after 2 h of inflation.
● Tourniquet deflation causes a transient decrease in core temperature,
● Caused by redistribution of body heat.
● Associated with the return, of a small amount of hypothermic blood from
the ischaemic limb

19. Haematological effects
● Effects  complicated.
● Associated with a global hypercoagulable state.
● increased platelet aggregation caused by catecholamines released in response to pain - from surgery and the
tourniquet itself.
● After deflation of the tourniquet, there is a brief period of increased fibrinolytic activity.
● Maximal at 15 min and returns to preoperative levels within 30 min.
● But may nevertheless cause increased bleeding.
● The increase in fibrinolysis is caused by release of tissue plasminogen activator.
● Produced by the vasa vasorum in the affected limb in response to the acidosis and hypoxemia associated with
tourniquet application.

20. Metabolic effects
● Deflation of the tourniquet after 1–2 h  associated with small increases in plasma concentrations of
potassium and lactate.
● Peak increases of 0.3 and 2 mmol/litre, respectively, occur 3 min after deflation.
● Lactate and carbon dioxide returning to the systemic circulation from the ischaemic limb cause a
reduction in arterial pH.
● Reperfusion of the ischaemic limb and the other haemodynamic changes associated with tourniquet
deflation can cause brief increases in oxygen consumption and carbon dioxide production.
● The magnitude of these changes correlates with the duration of ischaemia.
● All of these changes are fully reversed within 30 min of tourniquet deflation.

21. Pharmacological effects:
● Isolates the limb from rest of the body.
● Can alter the Vd of some medications alteration in the pharmacokinetics
of anaesthetic drugs
● time interval between antibiotic administration and tourniquet inflation –
important for antibiotic prophylaxis.
● Clinical evidence – 5-10 mins before inflation – good tissue penitration

22. Complications associated with the use of arterial tourniquets
Nerve injury
● The most common complication and
can be the most devastating.
● Lower limb tourniquets
● Lower limb – sciatic nerve, upper limb –
radial nerve
● Esmarch bandage associated with
higher incidence of nerve inury
● Large diameter nerve fibres are more
susceptible to pressure
Muscle injury
● The post-tourniquet syndrome results in
a swollen, stiff, weak limb.
● Very rarely the post-ischaemic swelling
and oedema, in combination with
reperfusion hyperaemia, may lead to
the development of a compartment
syndrome.
● Rhabdomyolysis has been reported, but
is extremely rare.
○ associated with unusually long
ischaemic times or high cuff inflation
pressures.

23. Skin injury
● Chemical burns – most common form of
skin injury
● occur when alcohol-based solutions used
for skin preparation.
● Friction burns resulting from movement of
poorly applied tourniquets.
Intraoperative bleeding
● Incomplete exsanguination of the limb
● A poorly fitting or underpressurized cuff.
● May also be caused by blood entering
through the intramedullary vessels of long
bones.
Vascular injury
● uncommon, but can be catastrophic.
● 7 in >5000 sx
● Acute vascular insufficiency – may occur
mechanical pressure from the tourniquet
damages atheromatous vessels, causing
plaque rupture.
● Recommend avoiding the use in patients with
peripheral vascular disease.

24. Tourniquet pain
● Poorly localized, dull tight aching pain
● During GA, manifests as ↑ HR , MAP
● More common ↓ GA (53 -67%), more common lower limb Sx’s
● Etiology – unclear, thought to be by unmyelinated, slow conducting c fibres
that are usually inhibited by Aδ fibres.
● Aδ fibres – blocked by mechanical compression in 30 mins while C fibre
continue functioning
● Release PG’s  ↑ pain perception by sensitizing and exciting the pain
receptors.
● Limb ischemia – central sensitization via NMDA receptors due to repeated
nociceptive stimulus

25. • Has important impacts in anesthesia.
• Application of EMLA cream
• Infiltration with local anaesthetics.
• Use of wider cuff with low cuff pressure
• Addition of opioids, clonidine, epinephrine along with LA’s in spinal block
• None has attained complete success in pain relief.
• IV drugs, Ketamine, dexmedetomidine, MgSO4, also been studied
• Only thing reliably works – tourniquet deflation.

26. Tourniquet-induced hypertension
● Gradual increase in arterial pressure is frequently observed after a
variable time after tourniquet inflation.
● The exact mechanism - not known.
● Suggested - represents activation of the sympathetic nervous system in
response to the development of tourniquet pain.
● Plasma norepinephrine concentrations increase in parallel with arterial
pressure during tourniquet inflation.
● Clonidine attenuates sympathetic activity and, if given preoperatively,
blunts the hypertensive response.

27. Contraindications
● No absolute C/I
● Adequate care should be taken in
○ Severe peripheral vascular diseases.
○ Sickle cell disease
○ Sever crush injury’
○ Diabetic neuropathy
○ Patients with h/o DVT and PE.

28. Thank you…