General disorders - First Aid

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First aid

First aid

General disorders

Fever and hyperthermia Heat illness Anaphylaxis Sudden "high blood pressure" Collapse Confusional state Epileptic seizures Panic attacks Electrocution Alcohol intoxication
  • Fever and hyperthermia
    • Measure the temperature
    • Main causes of the increase in body temperature
    • Signs and symptoms
    • What to do
  • Heat illness
  • Anaphylaxis
  • Sudden "high blood pressure"
  • Collapse
  • Confusional state
  • Seizures
  • Panic attacks
  • electrocution
  • Alcoholic intoxication

Fever and hyperthermia

The body thermoregulation processes depend on the hypothalamus and have the function of maintaining the internal temperature of our body on constant values, regardless of the temperature that is recorded outside. In healthy subjects, this temperature constantly hovers between 37 and 38 °.

Fever and hyperthermia are clinical manifestations of various disease conditions. When the body temperature rises above 37-38 °, this can mean that the body's heat production has exceeded the hypothalamus's ability to dissipate heat efficiently: in this case we speak of hyperthermia and it is in progress a sort of “failure” of thermoregulation in the face of the limits imposed by the laws that regulate the production and dissipation of heat. In fever, on the other hand, the hypothalamus resets its "ideal" temperature value upwards, activating the thermoregulatory mechanisms to realign the actual body temperature with the new, higher reference value.

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Measure the temperature

The body temperature measuring instrument is the common thermometer: simple to use, low cost and precise. But defining when a temperature is "pathological" is not so simple: in the healthy individual, in fact, the temperature varies according to the time of the day (in the morning it is lower than the afternoon on average by half a degree), hormonal (in women of childbearing age, during the pre-ovulatory phase it is lower than the average of 0.6-0.8 degrees centigrade in the post-ovulatory phase), physical activity, the calorie content of meals, exposure to sun and so on: this is the concept of the so-called intraindividual variability. Furthermore, even if it is possible to average all intraindividual variables, this average can in any case differ from individual to individual by almost 1 degree (interindividual variability).

The measured temperature also varies in relation to the location where it is detected: in the axillary cavity it is about half a degree less than the oral cavity, and this is slightly less than half a degree compared to that measured in the rectum.

Taking into account, therefore, this great variability, it can be said that 99% of healthy adults have a maximum oral temperature of 37.2 ° in the morning and 37.7 ° in the evening (which, measured rectally, becomes 37, 6 ° in the morning and 38.1 ° in the evening).

Values ​​above these are almost certainly indicative of a pathological condition, or fever; it is possible to speak of fever with values ​​lower than those indicated, but the probability of fever is almost negligible when values ​​of about 36.4 ° in the morning and 36.9 ° in the evening are recorded (rectally: 36.8 ° in the morning and 37.3 ° in the evening).

It would therefore be good for everyone to know their own personal daily thermal curve in conditions of well-being, so as to assess with confidence whether the temperature values ​​measured when not feeling well are pathological or not.

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Main causes of the increase in body temperature

The most common causes of fever are:

  • microbial infections;
  • tissue injuries (trauma, burns, surgery and so on);
  • malignant tumors, especially if advanced;
  • chronic inflammatory diseases (for example, many rheumatological diseases, such as vasculitis and connectivitis).

Hyperthermia, on the other hand, in most cases depends on stays in hot and humid environments, prolonged to the point that the organism is no longer able to dissipate its heat (heat stroke). This risk is particularly high in the elderly, especially if dehydrated (and therefore with little ability to sweat) or if they take drugs that inhibit sweating, such as many antispasmodics, some antihistamines, neuroleptics, antidepressants and antiparkinsonians, or drugs that promote elimination. of water from the body (diuretics and laxatives).

Young people can run into heat stroke if they carry out heavy physical activities in the heat: in such conditions, the risk is a rapid dehydration associated with the production of large quantities of heat caused by the contraction of the muscles (heat stroke from exercise); furthermore, hyperthermia in young people can depend on hormonal diseases (for example, thyrotoxicosis or pheochromocytoma) or it can represent an undesirable effect of particular drugs (such as neuroleptics) or drugs (amphetamines, cocaine, LSD, phencyclidine).

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Signs and symptoms

In fever, by definition, the oral or rectal temperature is above the normal limits, while the axillary temperature is much less reliable, as the skin can be colder than the bowels: for this reason, in doubtful cases, it is highly advisable to confirm the "external" temperature value with oral or rectal measurement.

A fever, even of a modest entity, can be accompanied by a marked feeling of tiredness, general malaise, headache, pain in the eyes, muscles (myalgias) and joints (arthralgias). The fact that the tissues are forced to "function" at temperatures higher than normal causes them to consume about 10-15% more oxygen: the consequence is that the heart is forced to increase its "work" and therefore the own frequency (tachycardia) with a feeling of "heart pounding" (heart rate) and higher frequency of respiratory acts (polypnea). Furthermore, especially in the elderly, fever can cause neurological disorders, such as mental confusion (sometimes severe, with complete disorientation, states of agitation, delirium, hallucinations), retention of urine (due to functional "blockage" of the bladder), profound state of sopore (lethargy) and even coma.

In about 3% of children under the age of 5 years, a rectal temperature above 39 ° can lead to seizures, although these are almost always "benign" and transient.

If the fever lasts a long time (many hours or days) it can hinder proper nutrition and cause losses of large quantities of water and minerals (electrolytes).

In more fragile patients, with limited ability to feed and drink (due to old age, due to the presence of other chronic diseases, due to precarious socio-economic and hygienic conditions or for other reasons), these phenomena can generate imbalances in a few days, thus serious in the composition of body fluids to lead to death.

In the case of subjects affected by hyperthermia, in addition to the increase in body temperature (internal and external), neurological disorders (hallucinations, delirium, lethargy), muscle rigidity (hypertonicity) and dilation of the pupils (mydriasis) may appear.

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What to do

In general, the mere presence of fever, even high, does not constitute an emergency and, if other worrying symptoms are not observed, it is not necessary to seek medical attention in the first 48 hours; however, there are some particularly dangerous conditions, for which we recommend not only an urgent visit to the doctor, but to go to the emergency room promptly, even if you are in the presence of a body temperature not very high (around 38-38, 5th):

  • patients recently undergoing chemotherapy or with HIV infections;
  • advanced tumors;
  • congenital immunodeficiencies;
  • patients with cough and with purulent or blood-stained sputum (hemoptysis) for more than a week (in fact, there is a high probability of pneumonia or tuberculosis);
  • recent trip to countries at risk of malaria (even if prophylaxis has been regularly performed);
  • appearance of neurological disorders (mental confusion, delirium, convulsions, lethargy or other);
  • appearance of breathing difficulties (wheezing or wheezing);
  • marked reduction in the amount of urine emitted, especially in the elderly (less than half a liter of urine per day is a condition indicative of severe dehydration);
  • persistent abdominal pain without diarrhea or with diarrhea with blood.

It is useful to report to the doctor the drugs that you are taking or have recently taken: substances such as neuroleptics, antidepressants, antispasmodics and others, in fact, could be precisely the cause of the increase in body temperature.

As for hyperthermia, it must be borne in mind that this is a life-threatening condition: all patients with suspected hyperthermia must therefore be taken immediately to the emergency room and during the journey, or in case of waiting, it is necessary to remove them all clothes and moisten the entire surface of the body with tap water at room temperature, then promoting evaporation, if possible, with a fan; if the patient is able to drink, he can take cold water, even from the refrigerator.

All these cooling maneuvers must be suspended if the presence of chills is observed, while the health personnel will put in place more drastic measures, after the ascertained diagnosis of hyperthermia.

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