The Basic And Clinical Studies Of The Effects Of Different Tourniquet Pressures And Pressure Employed

Part I:The basic studies of the effects of different tourniquet pressures on limb microcirculation in healthy volunteersObjective:To measure the effects of different tourniquet pressure on occlusion of arterial blood flow, and define the optimum pressure.Methods:Sixteen healthy volunteers were randomly applied four different tourniquet pressures on upper or lower extremity (three different pressures applied for observing ring finger nailfold microcirculation). Local tissue blood flow volume, local skin blood perfusion, ring finger and toe nailfold microcirculation were observed before tourniquet inflation, after inflation 0,3,5,8,10 min, and after deflation 0,3,5,8,10,15,25 min.Results:(1) Laser Doppler local tissue blood flow volume:Local blood flow volume in upper or lower extremity was statistical significant differences in four different tourniquet pressures at different time points (P<0.01). Local tissue blood flow volume in upper or lower extremity at different time points after tourniquet inflation were significant lower than that before inflation (P<0.01), and local tissue blood flow volume at 5 min after deflation significant higher than that before inflation (P<0.01). There was relationship between different tourniquet pressures and different time points. Upper or lower extremity blood flow volume was statistical significant differences after tourniquet deflation in four different tourniquet pressures (P<0.01). Paired comparison analysis showed that there were statistical significant differences between pressure 1 and pressure 3, pressure 1 and pressure 4 in upper extremity, and there were statistical significant differences between pressure 4 and pressure 1, pressure 4 and pressure 2 in lower extremity (P<0.01).(2) Local skin blood perfusion:Local skin blood perfusion was still differences between after deflation 15 min and before inflation. There was no statistical significant difference in different tourniquet pressures (P>0.05). (3) Nailfold microcirculation:There were statistical significant differences in blood flow and erythrocyte aggregation in ring finger and toe nailfold microcirculation in different tourniquet pressures at different time points (P<0.01). There were statistical significant differences in blood flow and erythrocyte aggregation in four different tourniquet pressures after inflation 30 seconds (P<0.01). Paired comparison analysis showed that there were statistical significant differences between pressure 1 and pressure 3, pressure 1 and pressure 4, pressure 2 and pressure 4 (P<0.01).Conclusion:When applied tourniquet pressure is 30 mmHg above systolic blood pressure for upper extremity,80 mmHg above systolic blood pressure for lower extremity, it was sufficiently occluded arterial and venous blood flow, and it had little effect on microcirculation after deflation, so it was recommended as the effective pneumatic tourniquet pressure in extremity surgery. Part II:Analytical report on survey of the use of tourniquet pressure in extremity surgery by the surgeon and nurseObjective:To assess the tourniquet pressures used by orthopedic surgeons and nurses, and recommend the effective pressures.Methods:The survey questionnaires were sent to 100 surgeons and 100 nurses in ten first class of the third grade hospital in Beijing by convenience sampling. Specific questions were asked about respondents information, tourniquet pressure they used and why, and tourniquet complications and so on.Results:A total of 198 survey responses were collected.52% (51/98) nurses and 54% (54/100) surgeons reported that they used a fixed tourniquet pressure. Many reported using 250 mmHg for upper extremity, and 340 mmHg (surgeon) or 330 mmHg (nurse) for lower extremity.4.8% (4/83) surgeons and 1.1% (1/89) nurses reported using 250 mmHg or less for lower extremity; 25.3% (21/83) surgeons and 4.5%(4/89) nurses reported using 200 mmHg or less for upper extremity. 9.2% (9/98) nurses and 14%(14/100) surgeons reported using a pressure related to the patient's systolic blood pressure. Many reported using 100 mmHg above systolic blood pressure for upper extremity, and 120 mmHg (surgeon) or 100 mmHg (nurse) above systolic blood pressure for lower extremity.34.9% (15/43) surgeons and 53.2% (25/47) nurses reported using 100 mmHg above systolic blood pressure or less for lower extremity; 20.9% (9/43) surgeons and 21.3% (10/47) nurses reported using 50 mmHg above systolic blood pressure or less for upper extremity. Most respondent agreed that inflation time should not exceed 60 minutes for upper extremity and 90 minutes for lower extremity, the tourniquet should be released for reperfusion 15 min, after which the tourniquet may be reinflation for another 1 h. Most of surgeons and nurses chose tourniquet pressure according to their working experience. The common complications were local skin impression, local pain, and local punctate hemorrhage.Conclusions:The survey show that many surgeons and nurses chose the higher tourniquet pressure, indicating that it is important to familiarity with associated literature and recommended the least effective pressures to minimize damage from tourniquet application. Part III:The studies of the effects of different tourniquet pressures on patients in total knee arthroplastyObjective:To investigated the effects of different tourniquet pressure on limb local blood flow volume, hemodynamics, and muscle microstructure distal to the tourniquet, and recommend the least effective pressures.Methods:Selective operation treatment of bilateral total knee arthroplasty for 11 patients with osteoarthritis, by using self-control study method, one lower extremity was chosen as experimental limb, and the other as control limb on random selection. The experimental limb was operated with tourniquet pressure of 80 mmHg above systolic blood pressure, and the control limb with fixed tourniquet pressure of 300～350 mmHg. Local tissue blood flow volume, upper extremity systolic arterial pressure, diastolic pressure, heart rate, bleeding volume, muscle microstructure damage distal to the tourniquet were observed before tourniquet inflation, after inflation 0,3,5,8,10,15,30,45 min, and after deflation 0,3,5,8,10 min and 24 h. Surgeons and nurses in operating room evaluated the effects of tourniquet during operation. Nurses in ward evaluated wound healing after operation.Results:The effects of two tourniquet pressure were similar, Bleeding volume was no statistical significant difference between experimental and control limb (P>0.05). Local tissue blood flow volume in both experimental and control limbs after tourniquet inflation 0 min were significantly lower than the basal value before inflation (P<0.01). Arterial flow was always eliminated, local tissue blood flow volume was lowest at the end of tourniquet inflation, which was statistical significant difference with that at other time points (P<0.01). Local blood flow volume increased gradually after tourniquet deflation, and there were statistical significant difference between each time points after deflation. The blood pressure was increased gradually from tourniquet inflation 0 min to 10 min, then decreased slowly, and significantly decreased after tourniquet deflation, recovered gradually after 3 min,10 min later, returned to level of before inflation. After tourniquet inflation, heart rate increased slowly. Heart rate was statistical significant difference between each time points after deflation (P<0.05). Muscle hypoxia-ischemia injury in control limb was more severe than experimental limb, nucleus showed early apoptotic changes, interstitial edema in small-vessel endothelial were severely.Conclusions:The tourniquet pressure used in experimental limb (80 mmHg above systolic blood pressure) had better hemostatic efficacy, and can improve postoperative recovery of patients undergoing total knee arthroplasty.