1. 1. Presentor : Dr.Kumar Moderator : Dr.vamsidhar TOURNIQUET IN ANAESTHESIA
2. 2. History Jean Louis Petit coined the word Tourniquet from theFrench word tourner (to turn) in 1718 when he used them for lower limb amputations to reduce blood loss. In 1873 , Johan friedrich august von esmarch introduced flat rubber tube wrapped repeatedly around the limb as tourniquet In 1904 Harvey cushing introduced pneumatic tourniquet to limb surgery Johan friedrich august von esmarch
3. 3. pneumatic tourniquets consist of three basiccomponents: 1. a cuff, similar to a blood pressure cuff,which is wrapped around a patient's limb and then inflated 2. a compressed gas source 3. pressure gauge, designed to maintain pressure in the cuff at a set value. Automatic tourniquets allow the intended pressure to be preset before inflation and have controllers that
4. 4. Arterial tourniquets are used for 1. extremity surgery to reduce blood loss and provide good operating conditions, 2. for intravenous regional anaesthesia,( Biers block ) 3. for intravenous regional sympathectomy in the management of complex regional pain syndromes and 4. for isolated limb perfusion in the management of localised malignancy
5. 5. Tourniquet pressure Tourniquet pressure : 50 100 mm of Hg above the systolic blood pressure. Upper limb 250 mm of Hg Lower limb 350 mm of hg Doppler occlusion pressure (DOP) : Upper limb DOP + 50 mm of Hg Lower limb DOP + 75 mm of Hg Above the DOPR. Upper limb 135 to 255 mm of Hg Lower limb 175 to 305 mm of Hg
6. 6. Tourniquet time : Initial time 90 minutes ideal is 45 60 minutes. >2 hours deflate for 5 minutes for reperfusion. Width of the cuff : Standard is 8.5 cm 15 cm conical shaped produces subsystolic pressure required to stop detectable flow. Ischaemic time information to surgeons : First 2 hours half hourly intervals. Next at 2.5 hours. Next every 15 minutes interval thereafter. Specification of Tourniquet
7. 7. Patho physiology
8. 8. Pathophysiological effects All arterial tourniquets, including the new automatic devices, can be associated with complications ranging from the minor and self- limiting to the debilitating and even fatal. Systemic effects are usually related to inflation and deflation of the tourniquet local effects and complications may result from either direct pressure to the underlying tissues or ischaemia in tissues distal to the tourniquet.
9. 9. NERVE INJURY most common complications associated with tourniquets and they range from paraesthesia to paralysis. The radial nerve,followed by the ulnar and median nerves in the upper limb the sciatic nerve in the lower limb are most commonly involved and it would appear that large diameter nerve fibres are more commonly affected.
10. 10. Esmarch bandage increases the cause of nerve injuries and this may explain the fact that nerves are more susceptible to mechanical pressure The effects of nerve compression at the tourniquet site may make injury caused by ischaemia or surgical trauma at a more distal site
11. 11. preventive measures Tourniquets use only recommended time. Check accuracy of the pressure. Effective pressure to achieve limb occlusion pressure. Use a cuff that properly fits the extremity.
12. 12. Muscle Injury Muscle injury is caused by ischaemia beneath and distal to the cuff. combination of ischaemia and mechanical deformation of the tissue. The extent of the damage is related to the duration of the ischaemia With time the intracellular concentrations of creatine phosphate, glycogen, ATP and oxygen decrease
13. 13. Creatine phosphate is depleted by 2 hrs and the ATP supply is exhausted by 3 hrs. Lactate and potassium concentrations and the P aCO2 increase with increasing duration of ischaemia Intracellular pH decreases a pH of 6.0 is reached by 4 hours. Intravenous pH in the limb decreases and a pH of
14. 14. Further ischaemia may produce irreversible muscle damage. After 2 hours at 200 300 mmHg, histological changes e.g. :inflammatory cells, focal necrosis, regional necrosis and hyaline degeneration may be seen in the muscle beneath the cuff significant increases in xanthine oxidase activity in both local and systemic blood
15. 15. post tourniquet syndrome The combined effect of muscle ischaemia, oedema and microvascular congestion The affected limb is stiff, pale, weak but not paralysed, and subjectively numbness without objective anaesthesia. Prolonged bleeding from surgical wound. It typically resolves over 1 6 weeks
16. 16. Compartment syndrome Relative complication of tourniquet. External and internal pressures - pain. Tense skin, swelling, weakness, parasthesia. Absent pulse irreversible paralysis. Causes & prevention : Trauma or surgery, time, pH. capillary permeability, Prolongation of clotting. Preoperative evaluation Time < 90 minutes.
17. 17. Routine tourniquet use results in weakness and delayed post operative recovery. Greater pressures produce greater functional impairment. Fast twitch fibres are affected more than slow twitch fibres. Wide, properly fitting cuffs require lower inflation pressures, which may reduce muscle injury
18. 18. Preventive measures Should it be necessary to use a tourniquet for longer than 2 hours it is recommended that the limb be reperfused periodically to allow for metabolic recovery of the muscle and maintenance of ATP levels. Recommendations vary from 10 minutes Hourly to 15 20 minutes every 2 hours
19. 19. VASCULAR INJURY Vascular injuries are rare They are usually associated with peripheral vascular disease and fractures of atheromatous plaques by pressure plaque dislodgement thrombosis due to lack of blood flow
20. 20. SKIN INJURY Skin injuries are uncommon. Esmarch bandages twist and stretch the skin while pressure necrosis and shearing have been described with pneumatic tourniquets because of inadequate padding or improper application. Chemical burns have been reported with alcohol based cleansing solutions held against the skin under pressure friction burns from the movement of a fully inflated tourniquet over bare skin
21. 21. HAEMATOMAS/ BLEEDING Because of tourniquet inflation, bleeders may not be identified intraoperatively. Once the tourniquet is released, a haematoma may develop or there may be a potential for acute blood loss superimposed on the haemodynamic changes of tourniquet release tourniquet release for haemostasis has actually been shown to increase bleeding Haematomas, arterial injuries and a compartment syndrome may all result in a delayed return of blood flow
22. 22. TOURNIQUET FAILURE Bleeding may occur despite a properly applied and inflated tourniquet, in a patient with noncalcified vessels. This is the phenomenon of tourniquet ooze. Blood bypasses the tourniquet through the medulla of the humerus or femur. It typically starts about 30 minutes after tourniquet inflation . Increasing the tourniquet pressure does not help Other causes of inadequate haemostasis include arterial and venous leakage due to inadequate pressure, calcified, incompressible vessels and inadequate
23. 23. Systemic effects CARDIO VASCULAR SYSTEM: Cardiovascular features are related to all stages of tourniquet use, from exsanguination to inflation, maintenance and deflation. Limb exsanguination and subsequent tourniquet inflation increase blood volume and systemic vascular resistance. CVP increases by up to 14 15 cmH2 O and blood volume by up to 800 ml following exsanguination of both legs. The changes in CVP and BP may be transient or may be maintained until tourniquet release.
24. 24. Tourniquet pain Approximately 30 60 minutes after tourniquet inflation, heart rate and blood pressure increase this is tourniquet pain. An awake patient will complain of a vague, dull pain that be-comes so severe as to be unbearable. It will occur despite an adequate sensory level. The incidence increases with increasing age and duration of surgery, and with lower limb surgery.
25. 25. The pain is probably mediated by the unmyelinated, slow conducting C fibres . The A-delta fibres are blocked by mechanical compression after about 30 minutes, while the C fibres continue to function. methods used to try to decrease the incidence of pain include the addition of adrenaline to the local anaesthetic, the type of local anaesthetic addition of clonidine or morphine and alteration of the dose of local anaesthetic The onset of tourniquet pain has been delayed by the application of EMLA cream to the tourniquet site and by
26. 26. With tourniquet deflation, CVP and MAP decrease, reaching a maximum at 3 minutes and taking approximately 15 minutes to return to normal. The decrease is a result of the combination of a shift of the blood volume back into the limb, a post ischaemic reactive hyperaemia, bleeding from nonligated vessels and washout of metabolites from the ischaemic areas into the systemic circulation . The cardiac index increases to compensate, mainly by an increase in the myocardial inotropic state The mean decrease in systolic blood pressure is 14 19 mmHg and the mean increase in heart rate is 6 12
27. 27. RESPIRATORY EFFECTS As the tourniquet is deflated and the limb reperfuses, CO2 And metabolites, e.g. lactate, are returned to the systemic circulation. The end tidal CO2(ETCO2) increases by 0.75 18 mmHg the lower limb > upperlimb and men >women, because of a mans greater muscle bulk
28. 28. The ETCO 2 peaks at 1 3 minutes, returning to baseline at 10 13 minutes in a spontaneously breathing patient . The increase in ETCO 2 will be prolonged in mechanically ventilated patients unless the minute volume is increased. The mixed venous saturation decreases transiently, but a drop in the arterial saturation is unusual
29. 29. CEREBRAL CIRCULATORY EFFECTS Middle cerebral artery flow increases after tourniquet deflation, related to the increased ETCO 2 This increase is larger with lower limb surgery than with upper limb Patients with reduced intracranial compliance may be at higher risk for adverse effects related to the increase in cerebral blood flow Maintenance of normocapnia prevents the increase in
30. 30. HAEMATOLOGICAL EFFECTS The tourniquet causes changes in both coagulability and fibrinolysis. Tissue damage induces coagulation factors and activates platelets. Pain (surgical and tourniquet) provokes catecholamine release, exacerbating the state of hypercoagulability Tissue ischaemia causes tissue plasminogen activator release, activating the antithrombin III and thrombomodulin protein C anticoagulant system in the affected limb
31. 31. Patients at high risk for deep vein thrombosis (DVT) and pulmonary embolism include those with lower limb trauma, prolonged immobilisation (>3 days ) or a history of DVTs. Venous embolism is common after tourniquet deflation. The embolus may consist of air, marrow contents, clot or cement. increased incidence of pulmonary emboli in total
32. 32. Sickle cell Haemoglobinopathy Sickling is predisposed to by circulatory stasis, acidosis and hypoxaemia, all of which happen with the use of a tourniquet. Systemic release of anaerobic metabolic products with cuff deflation may also induce sickling. Intravascular sickling may therefore theoretically occur with tourniquet use in susceptible patients.
33. 33. TEMPERATURE CHANGES In both adults and children, core temperature increases during tourniquet use Tourniquet inflation decreases heat transfer from the central to peripheral compartment, decreases the surface area available for heat loss and decreases the heat loss from the distal skin, allowing the temperature to rise.
34. 34. The increase in temperature may sometimes be larger than predicted, slow release of ischaemic metabolites, which raise the temperature, may occur via the bone In children the temperature may rise by as much as 1 1.7 oC After cuff deflation, a redistribution hypothermia may occur as the cold extremity is reperfused
35. 35. METABOLIC CHANGES With reperfusion of the affected limb, potassium, lactate, CO2 and other ischaemic metabolites are washed into the systemic circulation. Potassium and lactate concentrations increase for approx. 30 min and pH decreases transiently. Oxygen consumption (VO2) increases by 55% and CO2produc-tion (VCO2) by 80% 2 minutes post release. This increase in VO 2 provides the energy needed to replenish both the high-energy phosphate and oxygen stores depleted during ischaemia and the energy needed
36. 36. DRUG KINETICS Tourniquet inflation isolates the limb from the rest of the body, altering the volume of distribution, sequestering drugs in the limb (if given before inflation), or preventing them from reaching the limb (if given after inflation) To prevent postoperative infection, prophylactic antibiotics need to reach the tissues in adequate concentrations before tourniquet inflation at least 5 minutes is required
37. 37. Fentanyl and midazolam sequestered in the limb are released into the systemic circulation after cuff deflation. These increased levels may be clinically significant, especially in the elderly, and prolonged post-operative observation (up to 4 hours) is necessary
38. 38. contraindications 1. Peripheral vascular disease 2. Severe trauma to the limb 3. Head injury/ CNS disorder, peripheral neuropathy 4. Severe infection of the limb 5. DVT in the limb 6. Severe arthritic changes/ bony spurs/ previous fracture of the limb 7. Poor skin condition of the limb 8. Arteriovenous (AV) fistula 9. Lack of appropriate equipment 10. Sickle cell haemoglobinopathy