As the main target for high blood pressure, the structure of blood vessel wall of patients is destroyed. At the same time, the blood pressure of patients is relatively high, and the amount of bleeding during or after operation is relatively larger for patients with hypertension[14, 15]. Multiple studies have confirmed that the intraoperative blood loss of patients with knee osteoarthritis complicated with hypertension undergoing TKA surgery is significantly higher than that of patients without hypertension, and the postoperative blood loss of hypertensive patients is significantly increased[16–18]. Jai Hyung Park et al. reported that reported that hypertension was the second most common preoperative complication after anemia in arthroplasty patients and had a significant impact on perioperative blood loss. When other diseases are complicated with hypertension, the blood transfusion volume of the surgical patients can be obviously increased. Patients with hypertension have more blood loss during TKA skin incision exposure. The reasons for that may be although the patient's blood pressure has been controlled within a reasonable range, the fluctuation range of the patient's blood pressure during operation is relatively large, and the systolic blood pressure is often higher, increasing the blood loss during operation. In addition, when patients with hypertension use electrocoagulation or gauze for hemostasis during operation, the hemostasis effect is worse than that of normal patients, resulting in more blood loss during operation. Therefore, for patients with hypertension, it is of great significance to use tourniquet during TKA to reduce perioperative blood loss.
Tourniquet, as an important hemostasis device in surgery, is widely used in TKA surgery. In this study, the total blood loss of tourniquet used in TKA was significantly reduced compared with that of tourniquet used in simple osteotomy and osteotomy to the end of suture skin. Hypertension has no obvious effect on functional exercise and recovery after TKA operation. Patients who use tourniquets will suffer from pain and functional swelling in the early stage after operation, but will not have obvious effect on long-term effect. It is necessary to pay special attention to the fact that the use of tourniquets can significantly increase the risk of DVT and intermuscular vein thrombosis of patients.
Long-duration tourniquet use can lead higher pain scores and reduce functional recovery after TKA. Olivecrona et al. reported a study involving 577 patients for the first time TKA and a prospective study of 46 knee revision patients. The results showed that when the risk of complications increased with each additional 10 min of barometric tourniquet use, the risk of various complications is significant after 100 min increased. Okan Ozkunt et al. conducted a prospective randomized study of 69 patients using three different tourniquet usage methods during TKA process and found that long-duration doesn't show the advantage of bone cement infiltration, but it also does VAS score increased and KSS score decreased. In another randomized, double-blind, controlled study, Wang et al. found that instead of using the tourniquet throughout, using the tourniquet only during the implant placement procedure do not increase the amount of transfusions and surgical time. Patients experienced less pain on the first postoperative day, were able to start straight leg raising training earlier, and had fewer minor complications via limiting the time of tourniquet using time. Cai et al. also found that periodical use can reduce postoperative blood loss and total blood loss, limb relief body swelling and help with early rehabilitation training. In this study, tourniquets used during osteotomy, prosthesis installation and osteotomy to suture can significantly reduce postoperative hemorrhage and postoperative swelling rate. This may be due to the injury of vascular wall, muscle ischemia-reperfusion injury and rhabdomyolysis of the patient caused by tourniquet during operation, resulting in increased postoperative hemorrhage and severe limb swelling, affecting postoperative functional recovery.
The use of tourniquets will lead to an increase in the operative risks of hypertensive patients. Hypertensive patients have fragile vascular walls, reduced regulatory function, and are more prone to sudden cardiovascular events under stress. The use of tourniquets can stimulate sympathetic nerves and cause violent fluctuations in hemodynamics, thus increasing the risk of myocardial ischemia or acute myocardial infarction during operation[23, 24]. Anesthesiologists need to effectively control the stress response and maintain the stability of the operation with drugs inhibiting sympathetic nerves during operation. Tourniquet can also cause lung function damage to a certain extent. Vascular endothelial dysfunction in hypertensive patients leads to endothelin/nitric oxide imbalance, which may affect lung function. In this study, it can be seen that the incidence of postoperative anemia, DVT and intermuscular venous thrombosis in patients who use tourniquets throughout the course are significantly higher than those in the other two groups. When using tourniquets in patients with hypertension undergoing TKA, the use time of tourniquets should be carefully selected, and at the same time, the tourniquets should be closely monitored by anesthesiologists to avoid tourniquet reactions in patients.
To sum up, tourniquets could be used before placing the cement knee prosthesis, and loosened after the suture is completed and the pressure bandage is applied, which can obviously improve the intraoperative blood loss and the short-term postoperative functional effect of the patient, with fewer postoperative complications, but the long-term clinical effect needs further observation. The use of tourniquets in hypertension patients during operation will lead to increased probability of heart and lung injury and thrombosis. Patients with hypertension should be cautious in using tourniquets and use tourniquets individually.