What is the reason for my child's hypothermia after fever?
*For medical professionals to read for reference only ), the body temperature will be lower than 36 ℃, and some people will be lower than 35 ℃, and the body will feel cold. The subsequent hypothermia of a child with a fever can be very worrying for parents, as they have heard that hypothermia may indicate a serious infection, even worse than a fever. This phenomenon seems to be more common in young children with acute rash, but I have not been able to find an authoritative textbook/institution to explain it. Fortunately, these children I have followed up are usually in good condition, and their body temperature will slowly return to normal in the next 2-3 days. Next, I try to analyze the possible reasons. Before analyzing, we need to understand several concepts. 1 Normothermia & Hypothermia & Hypothermia There is a clear medical definition of hypothermia, but no description of what hypothermia is. In my opinion, hypothermia ≠ hypothermia. In order to understand the difference between the two, you must first know what normal body temperature is. ▌ The hypothalamus thermoregulatory center of normal body temperature maintains the stability of body temperature by regulating the process of heat production and heat dissipation: regulating muscle and liver metabolic activity to produce heat; regulating skin vasodilation and sweating and lungs (via breathing) for heat dissipation. Human body temperature fluctuates around 0.5°C throughout the day, usually lower in the morning and higher in the afternoon to evening. Children's body temperature is often slightly higher due to relatively strong metabolism and other reasons; body temperature can also temporarily rise after a lot of activity or violent crying. So, it's best to take your temperature when it's relatively calm. Therefore, normal body temperature has a range, not a fixed value. The range of normal body temperature is different in different locations: (△ from "Temperature measurement in paediatrics" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819918/) Regarding the range of normal body temperature, different textbooks (including There are also differences between different editions of the same textbook) and authorities, but the differences are small, and we do not need to be too serious. (△20 edition of "Nelson Pediatrics") (△21 edition of "Nelson Pediatrics") It can be seen that the new edition of "Nelson Pediatrics" defines a wider range of normal body temperature than the traditional (traditionally) range. ▌ The textbook definition of hypothermia is a core temperature below 35°C. Although core temperature is often referred to as ear temperature or rectal temperature (commonly known as rectal temperature), hospitalized hypothermic patients require temperature measurements at deep locations, such as the bladder, esophagus, nasopharynx, or central veins. Such as measuring rectal temperature, the probe should be 15cm deep into the rectum. These methods are impossible to implement in the home. If the rectal temperature measured at home is lower than 35 ℃, in principle, seek medical evaluation. In general, I hope parents don't get too nervous, after all, medically defined hypothermia is rare in children. ▌ Low body temperature There is no official official statement about low body temperature. But I think that the interval between the lower limit of normal body temperature and hypothermia can be defined as hypothermia, such as: - The core temperature is between 35°C and 36.6°C (most literatures regard 36.6°C as the normal body temperature lower limit).
- Or core temperature between 35°C and 35.5°C (35.5°C is considered to be the lower limit of normothermia in the 21st edition of Nelson Pediatrics).
The body temperature in this interval is not normal, but it does not meet the hypothermia standard, so it is reasonable to call it hypothermia. ▌ The method of measuring body temperature at home is convenient, but the accuracy is not as good as that of rectal temperature. Therefore, parents often find that the ear temperature is measured multiple times at the same time, and the results are different. For example, the angle of the tip of the ear thermometer that goes deep into the external auditory canal is skewed, or there is more cerumen in the external auditory canal, which will cause the infrared rays emitted by the tip to not reach the eardrum, and the measured value can be low. (△https://www.aboutkidshealth.ca/Article?contentid=30&language=ChineseSimplified) Usually we do not need to obtain accurate body temperature, after all, it is inconvenient to measure rectal temperature (it is an invasive operation, and children often resist, and even cause damage), so It is recommended to use an electronic thermometer to measure axillary temperature at home (applicable to any age), or to measure ear temperature (applicable to children ≥3 months old). Oral temperature measurement should be considered for children ≥5 years old. 2 Why does the body temperature appear low after the fever is gone? ▌First of all, let's understand the mechanism of fever and antipyretic: pathogens that infect the human body and their metabolites will induce human cells to release some factors, these factors eventually increase the hypothalamus temperature set point. In order for the body to reach the new set point, the body will Fever occurs. As the infection is controlled (perhaps by the fight against the autoimmune system, or with the use of effective antipathogenic drugs), the number of pathogens in the body gradually decreases, the concentration of pathogen-induced pyrogens decreases, and the hypothalamic thermoregulatory set point resets downward. As a result, the fever peak of the child gradually decreased, and the body temperature gradually returned to normal until the fever ceased. ▌ Why do some children have low body temperature after fever subsides? The up- and down-regulation of the hypothalamic body set point determines the rise and fall of body temperature. If an infected child has a fever first, then has a low body temperature later in the course of the disease, and there are no other signs of aggravation, I speculate that it is probably because the infection is under control, the concentration of the heat source suddenly decreases, and the hypothalamic temperature setting point decreases accordingly. Excessive (set position lower than normal), resulting in hypothermia. In clinical work, it is found that young children seem to be more prone to this phenomenon, especially children with acute rash in young children. It is speculated that it may be related to the imperfect development of the thermoregulatory center in young children. Of course, this is just my speculation and there is no evidence to prove it. I will continue to follow the research progress in this area. In fact, the regulation of body temperature by the brain thermoregulatory set point is still an unproven theory, and its molecular mechanism has not been fully revealed, but this theory can perfectly explain the process of thermoregulation, so it is widely accepted. 3 What should I do when my child's body temperature is low? Most of the children may only have temporary hypothermia, which is not a serious problem; while the body temperature of individual children is low at first, and then enters hypothermia. At this time, it is necessary to actively search for the cause and intervene. When the child's body temperature is low, we need to monitor the trend of body temperature changes, observe the child's mental state, appetite, and make a comprehensive judgment based on the child's previous condition changes. If the child can eat and drink and interact well with the family, there is usually nothing to worry about. For children with hypothermia, it is sufficient to provide normal clothing and coverage, and there is no need to excessively keep warm. If your child is not feeling well when the temperature is low, such as persistent malaise, reluctance to interact with family members, or refusal to eat, seek medical attention. If the child has hypothermia (core temperature below 35°C), and the measurement tool confirms that there is no abnormality, they should seek medical attention for possible serious infection, loss of body temperature, and endocrine disease. Source of this article: Dr. Yan of Pediatrics Author of this article: Dr. Yan of Pediatrics Responsible editor: Xiang Yu All the pediatric clinical knowledge doctor station apps you want to see 👇 1. Scan the QR code below 2. Click "Download Now" to download the Doctor Station App, anytime Subscribe anywhere~Copyright statement This article is reproduced, please contact - End - The medical community strives for the accuracy and reliability of its published content when it is approved, but it does not regard the timeliness of the published content and the accuracy of the cited materials (if any) and completeness, etc., and do not assume any responsibility for the outdated content, possible inaccuracy or incompleteness of the cited information. Relevant parties are requested to check separately when adopting or using it as a basis for decision-making.
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