At a family gathering a few days ago, my aunt said that she had an operation under general anesthesia some time ago, and when she entered the room, it was so cold that she shivered. It calmed down after a while. After listening to the uncle, he immediately said: “The son of my colleague in my unit was the same after the operation for appendicitis a few days ago. When the young man just returned to the ward, his teeth chattered and he only shouted that he was cold. Everyone said that the temperature of the air conditioner is not very low. Why is the boy so cold?”
Actually…
Cold is an appearance. The fundamental reason is that the patient’s body temperature decreases, especially the core temperature. At this time, the heat generation can only be accelerated by the chilling response. We cannot simply think that it is caused by air conditioning. Below, this article briefly discusses the role and significance of body temperature monitoring and warmth retention during surgery.
What is hypothermia?
The body temperature of a normal human body is relatively constant and fluctuates between 36.3°C and 37.2°C. Normal body temperature is a necessary condition for the body to carry out metabolism and normal life activities. and behavioral thermoregulation remained constant. However, under anesthesia, the patient loses the behavioral thermoregulation function (such as adding clothes or quilts, which is not conducive to the implementation of surgery), and can only rely on its own thermoregulation center to regulate the body’s heat production and heat dissipation processes. Heat production can be achieved through liver metabolism and muscle contraction, while under anesthesia, liver and muscle functions are basically inhibited, and heat production is limited. Heat dissipation mainly dissipates heat through the sweat glands on the body surface. Under anesthesia, the exposed area of the body surface increases. In addition, the temperature of the air conditioner is low, and the heat dissipation is greatly increased at this time. This decrease in heat eventually leads to the easy reduction of the patient’s body temperature. When it is lower than 36°C, it is called hypothermia. Some studies have found that the incidence of hypothermia in the perioperative period is as high as 50%-80%, so we must pay attention to body temperature. Protect.
What are the dangers of hypothermia?
Generally speaking, hypothermia has the following hazards, such as:
1. The decrease of body temperature directly leads to the decline of liver and kidney function, which affects the decomposition and metabolism of anesthetic drugs, which easily leads to the accumulation of anesthetic drugs, which affects the recovery of anesthesia and even delays recovery;
2. Induces respiratory complications such as pulmonary infection and increases the incidence of adverse cardiovascular events;
3. Low temperature leads to abnormal function of coagulation factors, disorder of acid-base balance, and inhibition of immune function.
Therefore, it is very important to maintain an appropriate body temperature during surgery and prevent perioperative hypothermia through intensive body temperature monitoring.
What causes a drop in body temperature?
1. Patient’s own factors: infants, the elderly, patients with systemic infections, critically ill patients, and patients with damaged skin integrity such as extensive burns are all people who are prone to hypothermia , for such fragile patients, body temperature protection must be strengthened.
2. Anesthesia methods and anesthesia drugs: both general anesthesia and spinal anesthesia can affect the mechanism of thermoregulation. During general anesthesia, the body’s hypothalamus thermoregulatory center, vascular activity, and skeletal muscle movement are all inhibited, and body temperature easily changes with ambient temperature. During spinal anesthesia, the local anesthetic blocks the preganglionic fibers of the sympathetic nerves, so that the blood vessels in the blocked area expand, and the body’s central body temperature is distributed to the periphery. At this time, the patient will feel fever and normal body surface temperature, but the central body temperature is decreased Yes, long-term surgery is prone to the paradoxical phenomenon of shivering but not feeling cold.
3. Factors such as surgery and blood transfusion: When the surgical site is disinfected, the patient’s body temperature will be taken away due to the large area of exposed skin, the scrubbing and volatilization of cold disinfectant. During the operation, the cold liquid flushing the chest and abdominal cavity or the body cavity for a long time will cause a lot of heat loss. Intraoperative large infusions of unwarmed fluids, especially cold bank blood, can cause hypothermia. In addition, in some endoscopic operations in urology and obstetrics and gynecology, when a large amount of irrigation fluid stored at room temperature is perfused, it is easy to cause the patient’s body temperature to drop.
How does our hospital prevent perioperative hypothermia?
1. Preoperative assessment and appropriate warm-up: fully assess the patient’s condition, surgery and anesthesia methods, and operation time before surgery to fully assess the possibility of hypothermia, and take measures to keep warm . When necessary, the cart and bedding should be preheated and kept warm during patient transport to reduce the exposure time of the patient in a hypothermic environment.
2. According to the national standard, the ambient temperature should be controlled between 22°C-25°C, and the room temperature will be adjusted appropriately for special patients such as newborns, premature infants, and the elderly.
3. For the operation time ≥ 1 hour, use the temperature probes in the nasopharynx, oropharynx, rectum, etc., to continuously monitor the body temperature dynamically during the operation, and maintain the body temperature to fluctuate within the normal range .
4. Warming artifact in the operating room: Patients who are prone to hypothermia during preoperative evaluation can be actively warmed by using heating blankets, heaters, cotton vest sleeves and other measures , reduce the patient’s heat loss and avoid hypothermia.
5. Use liquid heating equipment to warm the infusion of cold liquid, blood bank, and body cavity flushing fluid. The heating modes include heating with electric heating strips, heating with water bath, etc.
The significance of body temperature protection
Maintaining an appropriate body temperature during the operation and preventing the occurrence of hypothermia during the perioperative period can not only reduce the impact of hypothermia complications, reduce the occurrence of chills, but also improve the patient’s mood after anesthesia. Comfort, reduce surgical site infection, and promote postoperative recovery. For patients, intraoperative heat preservation is like the rising sun, which allows people to enjoy the warmth and comfort of bathing in the sun. It meets the requirements of comfortable medical care and is more humane, but it requires every anesthesiologist to strengthen the awareness of body temperature protection.
Author: Bao Rong, Gao Xinyue, Department of Anesthesiology, Punan Hospital, Pudong New Area, Shanghai
[Warm reminder] Please pay attention, here are a lot of professional medical science, to reveal the secrets of surgical anesthesia for you~