γγAt present, the diagnosis of fluid extravasation is mainly based on the presence of predisposing factors, clinical manifestations and laboratory tests, such as the presence of factors causing SIRS or sepsis, the presence of generalized edema, decreased blood pressure and central venous pressure, weight gain, hemoconcentration, hypoproteinemia, and more severe edema after supplementation with small molecule crystalloid substances, etc. In addition, the following tests should be performed: 1. Tissue interstitial pressure Measurement: The pressure in the tissue interstitium is not easily measured and the results are very inconsistent. The literature reports close to zero (atmospheric pressure) and negative pressure in subcutaneous tissues, and some people report that the interstitial pressure in the limbs is less than 2.67 kPa. interstitial pressure in the lungs is only 0.4 kPa during blowing and less than 1.33 kPa at rest. the use of anti-shock pants with a pressure of 4 kPa will block microcirculation, reduce tissue blood flow and lead to hypoxia. If the interstitial pressure exceeds 5.33kPa, fasciotomy decompression is required.γγ2. Interstitial fluid component analysis: interstitial fluid contains only a small amount of plasma protein. If the edema fluid can be collected and analyzed for protein content when the edema is severe, and the colloid osmotic pressure can be measured, the vascular permeability and recovery process can be observed. If no improvement is sustained, the prognosis is extremely poor. The osmotic concentration of edema fluid is much higher than the plasma osmotic concentration, sometimes reaching more than 350 mmol/L. The increase is mainly due to the formation of exuded proteins or other colloids.