The Relationship Between Application Of Different Tourniquet Pressures In Total Knee Arthroplasty And Postoperative Pain And Swelling

ObjectiveTourniquets are commonly used in clinical TKA surgery to control intraoperative bleeding.There are many advantages of using tourniquets as well as postoperative risks,among which postoperative limb swelling and pain are the most important risks.As is well-known,the methods of using tourniquets includes time-course methods and pressures methods.At present,the study of tourniquets is mainly focused on the time-course methods,meanwhile studies about the pressures methods are rarely reported.The aim is to study the relationship between the pressure of the tourniquet and the postoperative pain and swelling of the injured limbs,and also to explore the possible mechanism of the ischemia-reperfusion injury after the usage of tourniquets in surgery,and to try to reflect the ischemia-reperfusion injury through the changes of the serological indicators.In the end,experimental data and theoretical basis can be provided for how to use the tourniquet in clinical work.Methods1.Measuring clinical index: A total of 96 patients undergoing total knee arthroplasty at Nanjing General Hospital between June 2017 and January 2018 are included in this prospective,single-centered,randomized,parallel,controlled,and single-blind clinical research.Patients who meet the inclusion criteria will be randomly assigned to either the high pressure group or the medium pressure group or the low pressure group at a ratio of 1:1:1,in which the high pressure group uses a tourniquet pressure of 300 mmHg,and the middle pressure group uses a tourniquet pressure of 270 mmHg,and the low pressure group used a tourniquet pressure of 240 mmHg.Patients in all three groups are underwent the same preoperative preparation and preoperative examination.The day before the surgery,the visual analogue scale(VAS)is used to reflect the level of pain and the thigh circumference of the lower extremities is measured to indicate the degree of swelling of the injured limb(mesured at 10 cm above the patella with tape).Patients in all three groups are underwent the same anesthesia by the same surgical method.The same surgeon perform the surgery in the same way.The tourniquet is inflated before the incision and is deflated before the suture,together with controlling blood pressure intraoperative.Patients receive the same treatment and nurse after surgery.The VAS pain scores and thigh circumferences are measured on the first and second days postoperative respectively.2.Laboratory index:Patients who are included in the study are randomly divided into three groups,and after the same preoperative preparation and examination,5ml venous blood is drawn the day before surgery.An enzyme linked immunosorbent assay(ELISA)technology is used to detect the levels of SOD1,PGE2 and myoglobin in the serum which reflect the local oxidative stress level,inflammatory reaction level and muscle necrosis level respectively.The same surgeon perform the surgery in the same way and patients receive the same treatment and nurse after surgery.5ml venous blood is drawn to detect the levels of SOD1,PGE2 and myoglobin in the serum by ELISA technology.Results: 1.There is no difference in age,sex,BMI,blood pressure,tourniquets' time,preoperative VAS pain scores,preoperative limb swelling,preoperative SOD1,PGE2,myoglobin levels in serum,and operation time between the three groups before surgery.2.There is no difference in pain and swelling of the injured limb between the low pressure group(240mmHg)and the middle pressure group(270mmHg)on the first and the second day after surgery,while patients in the high pressure group suffer more pain and swelling sence the first day after surgery.3.In the high pressure group,SOD1 showe the biggest increased within 3 hours after operation and then gradually decrease till under the preoperative level.What's more,SOD1 in the low pressure group and the middle pressure group begin to drop from 3 hours after operation and is lower than the preoperative level,and the difference between the two groups is statistically significant.Within 3 hours and 8 hours after surgery,the content of PGE2 is increased in all three groups,especially the high pressure group.24 hours after surgery,it begin decrease and under the preoperative level.Within 8 hours and 24 hours after the operation,there were differences between the high pressure group and the low pressure group or the middle pressure group.Myoglobin also show the biggest increase within 3 hours after operation in three groups,especially the high pressure group and begin to decrease later.Only the low pressure group is lower than the preoperative level within 8 hours and 24 hours after operation,while the other two groups are higher than the preoperative level.There are significant differences between the three groups within 3 hours,8 hours,and 24 hours after operation except the low pressure group and the middle pressure group within 3 hours.Conclusions: 1.With the increase of the pressure of the tourniquet during the operation(>270mmHg),the pain and swelling of the injured limbs are more severe.That is to say,the patient's postoperative limb pain and swelling are positively correlated with the pressure of the tourniquet during the operation.2.The degree of postoperative ischemia-reperfusion injury from the different tourniquet pressures in TKA can be reflected by the serum markers SOD1,PGE2,and myoglobin.3.The mechanism of ischemia-reperfusion injury from the different tourniquet pressures in TKA may be related to oxidative stress,inflammation and muscle necrosis.