Arterial torniquet.

This presentation is open for all to see and get benefitted

1. ARTERIAL TOURNIQUET Dr Nisar Ahmed Arain Assistant Professor Anesthesia/Critical Care/ER

2. -TOURNIQUETS Pneumatic tourniquets --consists of three basic components --1-A cuff, similar to a blood pressure cuff, which is wrapped around a patients limb and then inflated --2-A compressed 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 compensate for small leaks

3. - TOURNIQUETS

4. - TOURNIQUETS

5. - ARTERIAL TOURNIQUETS -USES --1-Extremity surgery to reduce blood loss and provide good operating conditions --2-For intravenous regional anesthesia ( Biers Block ) --3-For intravenous regional sympathectomy in the management of complex regional pain syndromes and for isolated limb perfusion in the management of localized malignancy

6. -TOURNIQUET PRESSURES TOURNIQUET PRESSURE : --1--50 to 100 mm of Hg above the systolic blood pressure --Upper limb 250 mm Hg --Lower limb 350 mm of Hg DOPPLER OCCLUSION PRESSURE (DOP) --1-Upper limb DOP + 50 mm of Hg --2-Lower limb DOP + 75 mm of Hg above the DOPR --3-Upper limb 135 to 255 mm of Hg --4-Lower limb 175 to 305 mm of Hg

7. -SPECIFICATIONS OF TOURNIQUET TOURNIQUET TIME --Initial time 90 minutes and ideal is 45 to 60 minutes --If more then 2 hours deflate cuff for 5 minutes for perfusion WIDTH OF THE CUFF --Standard width is 8,5 cm --15 cm conical shaped procedures sub systolic pressure required to stop detectable flow ISCHEMIC TIME INFORMATION TO SURGEONS --First two hours – Half hourly intervals --Next at 2.5 hours --Next every 15 minutes interval there after

8. -PATHO PHYSIOLOGY

9. -PATHOPHYSIOLOGICAL EFFECTS --1-All arterial tourniquets, including the two automatic devices, can be associated with complications ranging from the minor and self timing to the debilitating even fatal. --2-Systemic effects are usually related to inflation and deflation of tourniquet --3-Local effects and complications may result from either direct pressure to the underlying tissues or ischemia in tissues distal to the tourniquet

10. -NERVE INJURY DUE TO TOURNIQUET PRESSURE --1-Most common complications associated with tourniquets are ranging from “Paresthesia to Paralysis”. --2-The RADIAL nerve followed by the ULNAR and MEDIAN nerves in the Upper limb --3-The SCIATIC nerve in the lower limb are most commonly involved and it would appear s that large diameter nerve fibers area more commonly affected

11. -ESMARCH BANDAGE --1-This increases the cause of Nerve injuries and this may explain the fact that nerves are more susceptible to mechanical pressure --2-The effects of nerve compression at the tourniquet site may make injury caused by ischemia or surgical trauma at a more distal site

12. -PREVENTIVE MEASURES --1-Tourniquets use only recommended time --2-Check accuracy of the pressure --3-Effective pressure to achieve limb occlusion pressure --4-Use a cuff which properly fits the Extremity

13. -MUSCLE INJURY --1-Muscle injury is caused by ischemia beneath and distal to the cuff --2-Combination of ischemia and mechanical deformation of the tissue --3-The extent of damage is related to the duration of ischemia --4-With the time the intracellular concentrations of -Creatine -Phosphate -Glycogen -ATP and -Oxygen decreases

14. - MUSCLE INJURY effects contd. --5-Creatine phosphate is depleted by two hours and the ATP supply is exhausted by 3 hours --6-Lactate and potassium concentrations and the PaCO2 increase with increasing duration of ischemia --7-Intracellula Ph decreases – sometimes a pH of 6.0 is reached after 4 hours of continuous pressure --8-Intravenous pH in the limb decreases and a pH of 6.9 corresponds to the fatigue point of muscle

15. - MUSCLE INJURY effects contd. --9-Further ischemia may produce irreversible muscle damage --10-After 2 hours at 200 to 300 mm Hg, histological changes --e.g --Inflammatory cells --Focal necrosis --Regional necrosis and --Hyaline degeneration These may be seen in the muscle beneath the cuff --11-Significant increase in ”xanthene oxidase” activity in both Local and Systemic blood

16. -POST TOURNIQUET SYNDROME --1-The combined effect of muscle ischemia, edema and Microvascular congestion --2-The affected limb is stiff, pale, weak but not paralyzed and subjectively numbness without objective anesthesia --3-Prolonged bleeding from surgical wound --4-It typically resolves over 1 to 6 weeks

17. -COMPARTMENT SYNDROME --1-Relative complications of tourniquet --2-External and Internal pressures – pain --3-Tense skin, swelling, weakness, paresthesia. --4Absent pulse – irreversible paralysis CAUSES and PREVENTION --1-Trauma or surgery -Time -pH --2-Capillary permeability, Prolongation of dotting --3-Pre- operative evaluation --4-Time < 90 minutes

18. - COMPARTMENT SYNDROME - CAUSES and PREVENTION --5-Routine tourniquet use results in weakness and delayed post operative recovery. --6-Greater pressure produce greater functional impairment --7-Fst twitch fibers are affected more then slow twitch fibers --8-Wide, properly fitting cuffs require lower inflation pressure, which may reduce muscle injury

19. - PREVENTIVE MEASURES COMPARTMENT SYNDROME --1-Should it be necessary to use a tourniquet for longer than 2 hours --2-It is recommended that the limb be Re-Perfused periodically to allow for metabolic recovery of the muscle and maintenance ATP levels --3-Recommendations vary from 10 minutes hourly to 15 to 20 minutes every 2 hours

20. -VASCULAR INJURY COMPARTMENT SYNDROME --1-Vascular injuries are rare --2-They are usually associated with peripheral vascular disease and fractures of Atheromatous plaques by pressure --3-Plaque dislodgement --4-Thrombus due to ack of blood flow

21. -SKIN INJURY --1-Skin injuries are common, Esmarch bandages twist and stretch the skin --2-While pressure Necrosis and sharing have been described with pneumatic Tourniquets because of inadequate padding or improper application --3-Chemical burns have been reported with alcohol based cleansing solutions held against the skin under pressure --4-Friction burns from the movement of a fully inflated Tourniquet over bare skin

22. -HAEMATOMAS/BLEEDING --1-Because of Tourniquet inflation, bleeders may not be identified intra-operatively --2-Once the Tourniquet is released, a hematoma may develop or there may be a potential for acute blood loss super-imposed on the hemodynamic changes of Tourniquet release --3-Tourniquet release for hemostasis has actually been shown to increase bleeding --4-Haematomas, arterial injuries and a compartment syndrome may all result in a delayed return of blood flow

23. -TOURNIQUET FAILURE --1-Bleeding may occur despite a properly applied and inflated Tourniquet, in a patient with non-calcified vessels --2-This is the phenomenon of tourniquet ooze --3-Blood bypasses the Tourniquet through the medulla of the humerus or femur. It typically starts about 30 minutes after Tourniquet inflation. --4Increased the Tourniquet pressure does not help --5-Other causes of inadequate hemostasis include arterial and venous leakage due to inadequate pressure, calcified incompressible vessels and inadequate

24. -SYSTEMIC EFFECTS -CARDIOVASCULAR SYSTEM --1-Cardio-vascular features are related to all stages of Tourniquet use, from exsanguination to inflation maintenance and deflation --2-Limb exsanguination and subsequent Tourniquet inflation increase blood volume and systemic vascular resistance --3-CVP increases by upto 14 to 15 cm H2O and blood volume by upto 800 ml following exsanguination of both legs --4-The changes in CVP and BP may be transient or may be maintained until Tourniquet release

25. -TOURNIQUET PAIN --1-Approximately 30 to 60 minutes after Tourniquet inflation, Heart rate and Blood pressure increase this is due to Tourniquet Pain --2-An awake patient will complain of a vague, dull pain that becomes so severe as to be unbearable --3-It will occur despite an adequate sensory level. --4-The incidence increases with increasing age and duration of surgery and with lower limb surgery

26. - TOURNIQUET PAIN contd. --5-The Pain is probably mediated by the unmyelinated, slow conducting C fibers --6-The A-Delta fibers are blocked by mechanical compression after about 30 minutes, while the C-fibers continue to function --7-Methods used to try to decrease the incidence of pain include the addition of adrenaline to the local anesthetic, the type of local anesthetic. Addition of clonidine or morphine and alteration of the dose of local anesthetic has very good action --8-The onset of “Tourniquet Pain” has been delayed by the application of EMLA cream to the tourniquet site and by this method pain feeling is reduced

27. - TOURNIQUET PAIN contd. --9-With Tourniquet deflation, CVP and MAP decrease reaching to a maximum at 3 minutes and taking approximately 15 minutes to return to the normal value --10-The decrease is the result of combination of a shift of the blood Back into the limb, a post-ischemic reactive Hyperemia bleeding from non ligated vessels and washout of the metabolites from the ischemic areas into the systemic circulation. --11-The cardiac index increases to compensate, mainly by an increase in the myocardial inotropic state -12-The Mean decrease in systolic blood pressure is 14 to 19 mm Hg and the mean increase in Heart rate is 6 to 12 bpm

28. -RESPIRATORY EFFECTS --1-As thee Tourniquet is deflated and the limb Re-perfuses, CO2 and metabolites e.g Lactate are returned to the systemic circulation --2-The End tidal CO2 (ETCO2) increases by 0.75 to 18 mm Hg and -Lower limb is > upper limb and -Men > women, because of mans greater muscle bulk

29. - RESPIRATORY EFFECTS contd. --3-The ETCO2 peaks at 1 to 3 minutes, and then returning to base line at 10 to 13 minutes in a spontaneously breathing patient. --4-The increase in ETCO2 will be prolonged in mechanically ventilated patients unless the minute volume is increased --5-The mixed venous saturation decreases transiently but a drop in the arterial saturation is un-usual

30. - CEREBRAL CIRCULATORY EFFECTS --Middle cerebral Artery flow increases after Tourniquet deflation related to the increased ETCO2 --This increase is larger with lower limb surgery than with upper limb --Patients with reduced intracranial compliance may be at a higher risk for adverse effects related to the increase in cerebral blood flow --Maintenance of normocapnia prevents this increase

31. -HAEMATOLOGICAL EFFECTS --1-The Tourniquet causes changes in both coagulability and fibrinolysis. --2-Tissue damage induces coagulation factors and activates platelets. Pain (surgical and Tourniquet) provokes catecholamine release, exacerbating the state of hyper-coagulability --3-Tissue ischemia causes tissue plasminogen activator release, activating the antithrombin 111 and thrombomodulin – protein C anticoagulant system in the affected limb

32. - HAEMATOLOGICAL EFFECTS contd. --4-Patients at high risk for deep vein thrombosis (DVT) and Pulmonary Embolism Include those with lower limb trauma, prolonged immobilization (.>3 days) or a history of DVT’s -- 5-Venous Embolism is common after tourniquet deflation --6-The Embolus may consists of air, Marrow contents, Clot or Cement --7-Increased incidence of pulmonary emboli in total

33. -SICKLE CELL HAEMOGLOBINOPATHY --1-Sickling is predisposed to by -Circulatory stasis -Acidosis and -Hypoxemia All of these happen with the use of Tourniquet --2-Systemic release of anaerobic metabolic products with cuff deflation may also induce sickling --3-Intravascular sickling may therefore theoretically occur with Tourniquet use in susceptible patients

34. -TEMPERATURE CHANGES --1-In both adults and children, core temperature increases during tourniquet use --2-Tourniquet inflation decreases heat transfer from the central to the peripheral compartment, decreases the surface area available for heat loss and decreases the heat loss from the distal skin, allowing the temperature to rise

35. - TEMPERATURE CHANGES contd. --3-The increase in temperature may sometimes be larger than predicted slow release of ischemic metabolites, which raise the temperature may occur via the bone --4-In children the temperature may rise by as much as 1 to 1.7 Degree Centigrade. After cuff deflation a “Re- distribution hypothermia” may occur as the cold extremity is Re-perfused

36. -METABOLIC CHANGES --1-With Re-perfusion of the affected limb, Potassium, Lactate, CO2 and the other ischemic metabolites are washed into the systemic circulation --2-Potassium and Lactate concentrations increase for approximately 30 minutes and pH decreases transiently. --3-Oxygen consumption (VO2) increases by 55% and CO2 production (VCO2) by 80% 2 minutes post release --4-This increase in VO2 provides the energy needed to replenish both the high energy Phosphate and oxygen stores depleted during ischemia and the energy needed is fulfilled to some extent

37. -DRUG KINETICS --1-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 the inflation) --2-To prevent post operative infection, prophylactic antibiotics need to reach the tissue in-Adequate concentrations before tourniquet inflation - for this atleast 5 minutes is required

38. --3-Fentanyl and Midazolam sequestered in the limb are released into the systemic circulation after cuff Deflation --4-These increased levels may be clinically significant, especially in the elderly, and prolonged post-operative observation (upto 4 hours) is necessary. -DRUG KINETICS contd.

39. --1-Perpheral 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 Hemoglobinopathy -CONTRA-INDICATIONS