compartment syndrome has a high incidence in patients with a variety of diseases, including fractures, and delayed diagnosis or without intervention can lead to severe adverse prognosis, such as limb deformities, amputations and even death. Early diagnosis and early intervention are important, especially early diagnosis. Now, the diagnosis of compartment syndrome in clinical is based on medical history, clinical manifestations and measuring the compartment pressure by fine needle puncture. However, this diagnostic method is not easy to achieve early accurate diagnosis and non-invasive continuous monitoring. The study found that the increase of compartment pressure can lead to local changes of hemodynamic, tissue metabolism and nerve function. There are also studies and reports of near-infrared spectral tissue oxygen measurement technology, ultrasonic Doppler technology, near-infrared spectral pulse oxygen measurement technology and infrared thermal imaging technology can be used for noninvasive monitoring of acute compartment syndrome, but it is not clear that which is better above in early diagnosis of acute compartment syndrome.

The purpose of this study was to simulate the process of early pressure increase in the compartment by pressurizing the volunteers' calves by cuff, and then measured the tissue oxygen in the Anterior fascia compartment using a non-invasive monitor of the tissue oxygen parameters, the ultrasonic machine measured the blood flow signal of the upper and lower backbone blood vessels, and the blood oxygen meter to measure the blood saturation of the upper and lower ends of the limb. The infrared thermal imager measured the near and far limb temperature of the hemostatic belt and the two-point identification of the skin sensory nerve function at the far end of the fascia chamber. Then compare the correlation of these indicators with pressure changes.

The participants is health volunteers, age 18-60 years. When the participants agree to participate in the experiment, the experimenter first needs to explain the experimental process to the participants, and ask the participants to agree and sign the informed consent before they can conduct the experiment. The experiment was conducted in the emergency medicine department of a university-affiliated top three hospital.

When the participants are included in the experimental study, the general demographic information of the participants, such as name, gender, age, etc., is first collected. Ensure the experimental environment is comfortable, ambient temperature 20-24℃, ambient humidity 50-60%. Participants have loose clothing on their lower limbs to avoid pressure on their limbs. Take the supine position, keep the calf hanging, support the heel, make the calf level flush with the heart, rest for 5 minutes.

The monitor (M3002A, Philips Medizin Systeme Boeblingen GmbH, Germany) was used to continuously monitor the electrocardiogram, the left upper arm measured blood pressure (BP), and the right middle finger to monitor pulse oximetry (SpO2). The calf circumference was measured at the midpoint of the bilateral humerus with a soft ruler. The maximum thickness of anterior fascia compartment was measured at the midpoint of the tibia using an ultrasonic machine (Acclarix AX8, Shenzhen Libang Precision Instrument Co., Ltd., China).

The random number table method selects one side of the calf as the experimental side and the opposite side as the control side.

(8) The following parameters were recorded at baseline (pressure 0mmHg in the calf tourniquet on both sides): (1) heart rate, blood pressure; (2) right middle finger, lower limbs, middle toe finger vein oxygen SpO2; (3) bilateral Local blood tissue parameters (TOI, THI, ΔCHb, CHbO2, ΔCtHb) in the calf; (4) Near-infrared thermography temperature values (T-u1, T-u2) in the knee and thighs of the lower leg and the instep and toe Near-infrared thermography temperature values (T-d1, T-d2); (5) bilateral radial artery ultrasound Doppler measurement parameters (D-pa, S-pa, Vs-pa, Vd-pa, DRAF-pa) Ultrasound Doppler measurement parameters of bilateral iliac veins (D-pv, S-pv, Vs-pv, Vd-pv), bilateral posterior tibial artery and dorsal artery ultrasound Doppler measurement parameters (Vs-pta, Vd -pta, SFAF-pta, Vs-da, Vd-da, SFAF-da). (6) Two-point identification threshold TPD.

In turn, the experimental side calf tourniquet was inflated and pressurized to a pressure value of 20, 30, 40, 50, 60, 70, 80 mmHg, and the pressure inside the tourniquet was up to 10 s during pressurization, and maintained stable for 1 min, measured and the above indicators were recorded within 3 min. During the experiment, the subjects were closely monitored for adverse reactions. At the end of the study, the observation was continued for 30 minutes, and the drinking water was at least 500 ml, and the limb sensation, pain and urine color were continuously observed within 24 hours.

Inclusion Criteria:

• Healthy adults, aged 18-60 years; No obvious cardiovascular diseases such as cardiovascular and cerebrovascular diseases; Complete limbs without deformity and no history of lower limb trauma; Informed consent

Exclusion Criteria:

• pregnancy or use of oral contraceptives; History of diabetes; History of deep vein thrombosis; Peripheral neuropathy; peripheral vascular disease; History of rhabdomyolysis