Effects of low hemoglobin on the body of perioperative patients

In clinical work, we often encounter patients with low hemoglobin. Hemoglobin, as an important component of the body, mainly exists in red blood cells and is an important carrier for transporting O2 in the human body.

It is generally believed that when hemoglobin is less than 90g/L, it is moderate anemia, less than 60g/L, it is severe anemia, and less than 30g/L, it is extremely severe anemia. Mildly reduced hemoglobin will not have a great impact on perioperative patients, but as the degree of hemoglobin decreases, the body's physiological functions will be affected to varying degrees. For patients with moderate to severe reductions, the difficulty of perioperative anesthesia management will increase accordingly.

As an important carrier of O2, when hemoglobin decreases, the body's oxygen carrying capacity decreases. In daily life, the body has certain compensation and adaptability, and it will not cause a big impact. Although the blood oxygen saturation of patients with low hemoglobin is still within the normal range at this time, their own oxygen capacity and oxygen reserve are reduced. For patients with moderate to severe anemia, during general anesthesia surgery, due to the decrease in the body's oxygen carrying capacity, the oxygen supply to the brain tissue may be reduced, and the cerebral blood oxygen saturation will decrease during surgery, which will prolong the patient's recovery period and increase the incidence of postoperative cognitive dysfunction. Not only that, the decrease in hemoglobin will also increase the patient's breathing depth and frequency during the recovery period. If the patient has respiratory diseases at this time, it will be a major test for his lung function.

At the same time, when the body's oxygen carrying capacity decreases due to the decrease in hemoglobin, in order to meet the oxygen supply of tissues, the body will compensatorily increase cardiovascular functional activities, increase the heart rate, and enhance myocardial contractility, and mobilize its own heart pump reserve function in a quiet state.

However, during the perioperative period, surgical stimulation, bleeding, infection and other factors may lead to the excitement of the patient's sympathetic nervous system. In this case, the heart cannot increase its own functional reserve to compensate for the decrease in oxygen carrying caused by low hemoglobin, and the oxygen supply of the body's tissues and cells will be affected to varying degrees, reducing the patient's recovery ability and increasing the possibility of accidents. When the oxygen supply to tissues decreases, the body's aerobic respiration decreases, and anaerobic respiration increases, which will produce more lactic acid to damage the body's own microenvironment and increase the burden on the functions of organs such as the heart and kidneys; and when the oxygen supply to cells decreases, the electron transfer of the oxidative respiratory chain will also be affected, the amount of ATP produced will decrease, and the energy produced by the cells themselves will decrease. The impact on important organs such as myocardial cells and nerve cells is self-evident.

When anesthesiologists conduct preoperative visits, if they encounter patients with low hemoglobin, they must consider the cause of the condition. Different causes will increase different risks for patients during the perioperative period. For example, female patients during menstruation will increase the possibility of bleeding and infection due to reduced immune function and changes in coagulation function; the incidence of nausea and vomiting in patients with chronic peptic ulcer bleeding will increase during the perioperative period; some patients have blood system diseases, tumors and other consumptive diseases, long-term malnutrition, etc., which will increase the risks of surgery and anesthesia.

For patients with clinically low hemoglobin, it is very important to find the cause, carry out effective and regular treatment, and supplement their nutrition through diet, etc. When encountering patients with extremely severe low hemoglobin or emergency surgery, it can also be relieved by transfusing concentrated red blood cells. Regardless of the treatment method, increasing the hemoglobin content and increasing the oxygen-carrying capacity of red blood cells are extremely important for the safety of patients during the perioperative period.

Wang Jing, Department of Anesthesiology, The Third Hospital of Hebei Medical University

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