We often encounter allergic reactions and infusion reactions in clinical practice, both of which are fierce, which requires us to diagnose quickly and deal with them accurately.
Allergic reaction is a kind of immune reaction, and the substance that causes allergic reaction is called allergens. There are many kinds of allergens, and some components of plants (pollen, dry grass, etc.), animals (chiggers, bee venom, etc.), drugs (penicillin, sulfonamide, etc.), and food (mushrooms, strawberries, oysters, etc.) are allergens for sensitive people. Allergic reactions can be caused by contact between the allergen and the mucous membrane of the respiratory tract or skin or by ingestion into the digestive tract. For an allergic reaction to occur, there must be contact between the allergen and the corresponding antibody (mainly IgE).
IgE antibody is a pro-cellular antibody that attaches to the surface of mast cells and basophils, turning them into sensitive cells. Among them, mast cells are widely and abundantly present in the mucosa of the subcutaneous, respiratory, digestive, and reproductive systems, and the cytoplasm is rich in secretory granules. When sensitive mast cells (and/or basophils) encounter allergens, they start to secrete large amounts of histamine and other active substances with vasodilatory properties, causing vasodilation, increased capillary permeability, and increased exudate, resulting in local redness, swelling, burning, runny nose, tears, sneezing, etc.
Prompt administration of antihistamines may bring relief. In another kind of allergic reaction (such as allergic asthma), the mast cells secrete not histamine but slow reachingubstance (SRS), whose effect is to make the smooth muscle contract continuously, and antihistamines are ineffective, but immediate injection of epinephrine can be relieved.
Clinically, allergy tests should be performed for drugs that frequently cause allergy, and those that are positive should be abandoned. Allergic patients with known allergens should avoid re-exposure to the allergen if possible. Desensitization is required for drugs that are known to be allergic and have to be used (e.g., trauma patients allergic to tetanus antitoxin).
Common clinical types of infusion reactions.
1.Febrile reaction
It is often caused by the input of pyrogenic substances (pyrogenic sources, dead bacteria, free bacteriophage proteins, other proteins and non-protein organic or inorganic substances), and the mechanism is that some factors during the infusion process directly or reflexively cause systemic capillary spasm, resulting in a series of symptoms due to impaired microcirculation.
2.Acute pulmonary edema
The mechanism is caused by the rapid increase of pulmonary venous pressure and the subsequent increase of pulmonary capillary pressure, which causes the intravascular fluid to infiltrate into the interstitium and alveoli of the lungs to form acute pulmonary edema.
3.Thrombophlebitis
It is caused by the chemical reaction of the local venous wall caused by the long-term infusion of highly concentrated and irritating drugs, or the long time of placing the irritating plastic tube in the vein, or the local venous infection caused by the failure to strictly perform the aseptic operation during the infusion process.
4.Air embolism
If the air inside the infusion catheter is not exhausted or is unattended during the pressurized infusion, the gas enters the blood circulation because the catheter gas is not exhausted during the infusion, and if the amount of gas is small, it is pressed into the pulmonary artery by the right ventricle and dispersed into the small pulmonary artery and finally reaches the capillaries, so the damage is small. However, if the amount of air is large, the air in the right ventricle blocks the entrance to the pulmonary artery, so that blood cannot enter the lungs, causing severe hypoxia can cause immediate death.
From these we can see that the two are different from each other in terms of mechanism and most of them can be avoided. Especially infusion reactions, if we can do the above mentioned points can reduce the occurrence, for allergic reactions must master the positive test allergy judgment criteria, for can not be fixed to be regarded as allergic, in addition to detailed inquiry allergy history and family history, this will also reduce the occurrence of allergies, but also reduce the occurrence of disputes.
It is also important to do a good job of training in this area, so that doctors and nurses know what allergic reactions and infusion reactions are, and how to explain and handle the occurrence of reactions.
In general, it is not difficult to diagnose allergic reactions and infusion reactions based on experience. However, some are more ambiguous and it is more difficult to really identify them. The two themselves overlap, and one type of infusion reaction is an allergic reaction. Fortunately, the two treatments have a lot in common. So the topic is quite complex, but there are clinical rules to follow.
The first thing that should be clear about allergic reactions is that there is a clear correlation with the type of drug and the physical differences of the patient, while infusion reactions are more associated with the environment and nursing practice of infusion. Secondly, analyze from the incidence within the time window: allergic reactions are disseminated, while infusion reactions are concentrated within a certain period of time and will continue to occur if the triggering factors cannot be removed.
Again, analyzed in terms of symptoms: allergic reactions are mostly seen as rash, urticaria, angioneurotic edema, induced asthma, anaphylaxis, etc. In contrast, the vast majority of infusion reactions are manifested as chills and sudden rise in body temperature, which usually appear within 30 minutes to 1 hour after infusion, and some can occur within 15 minutes. Chills are often the first reason for patients to seek a physician again. Drug fever due to allergic reactions occurs more slowly and is stubborn without stopping the drug. The chance of a sudden rise in body temperature is low.
Treatment: Both require anti-allergy and hormone use. However, allergic reactions focus on anti-allergic treatment, using epinephrine if necessary. Infusion reactions, on the other hand, focus on heat remission.