Blood pH is an indicator of blood pH, the negative logarithmic value of the concentration of hydrogen ions in the blood. The pH of blood in a normal person remains relatively constant and varies between 7.35 and 7.45. When the pH of blood is below 6.9 or above 7.7, life-threatening conditions can occur. Usually arterial blood is taken and tested under conditions without exposure to air. The effect of pH on the body is mainly on the excitability of neuromuscular tissues, and within a certain range of pH values, alkalinity increases and excitability increases, while acidity increases and excitability decreases. Normal human blood pH changes very little, mainly relying on the role of the buffer system formed by anti-acid or anti-check substances in the blood and the normal lung respiratory function and kidney excretion function to achieve, if these functions are poor or affected by disease, acid-base balance disorders will occur.