AST Guidelines for Best Practices for Safe Use of Pneumatic Tourniquets

7 inflation and deflation showed no significant increase in sickled cells compared to preoperative samples. 29 He concluded that patients with sickle cell disease should not be denied an operative procedure that requires the use of a tourniquet if the procedure is necessary and the steps are taken to minimize sickling. Other evidence suggests that with proper precautions, tourniquets may be able to be used with no significant damaging effects to the sickle cell patient. A complication rate of 12.5% was reported in four studies included in a review article that involved ninety-six patients. 30 3. Constriction and subsequent ischemia of extremities causes metabolic changes that include build-up of lactic acid and increased levels of PaCO 2 and potassium, and decreased levels of PaO 2 and pH. 10,11 Upon cuff deflation the anaerobic metabolites are immediately released into the patient’s systemic circulation. The metabolites cause a syndrome called “myonephropathic metabolic syndrome” that can cause hyperkalemia, hypotension, metabolic acidosis, myoglobinuria, myoglobulinemia and possibly renal failure. 11,25,31 The extent of the syndrome depends on the age and health status of the patient, duration of tourniquet time and size of the extremity. 10 Additionally, the metabolic changes are increased when bilateral tourniquets are used. 11 Typically the metabolic changes are reversed within thirty minutes after cuff deflation. 11 4. The cardiovascular system is affected by the use of a tourniquet starting with exsanguination through deflation. Healthy patients are minimally affected by the hemodynamic changes, but patients with deficient cardiac function can be adversely affected. Exsanguination and cuff inflation causes an increase in the central venous pressure (CVP). 9,32,33 Diastolic and systolic pressures and heart rate increase after 30 – 60 minutes of cuff inflation due to ischemia and tourniquet pain and continue until the cuff is deflated. 11 Monitoring the patient is critical during cuff deflation because it causes a rapid decrease in CVP and arterial pressures. 10,11 The short period of hypotension after cuff deflation can cause myocardial depression and possibly cardiac arrest. 33-36 These hemodynamic changes are due to both an influx of blood volume back into the extremity and the rapid entry of metabolites that built-up in the extremity into the systemic circulation. 5. Changes to the respiratory system rarely occur and if it occurs it is usually during cuff deflation. 11 The end-tidal carbon dioxide (EtCO 2 ) increases due to the rapid entry of hypercapnic venous blood and metabolites into the patient’s systemic circulation. 9,10,33 Increases in the EtCO 2 are also related to the length of ischemia, use of the tourniquet on lower extremities and males are affected more than females due to males usually having a greater muscle bulk. 11 The EtCO 2 usually returns to normal baseline readings within 10 – 13 minutes after cuff deflation in spontaneously breathing patients but may take longer in mechanically ventilated patients. 33-36 Cerebral circulation is affected by the increased EtCO 2 ; after cuff deflation the cerebral blood flow is increased for approximately two minutes and returns to normal in about ten minutes. However, patients who have a compromised cerebral circulation may be at an increased risk for complications. The anesthesia provider will attend to maintaining normocapnia levels in the patient to prevent