Injections involve the introduction of solutions (e.g., drugs) into the body using a syringe and needle or by high-pressure injection (needle-free injection).
Types of injection
Injection with a needle-free injector
A spring-loaded plunger is used to inject a thin jet under high pressure through a nozzle that penetrates the skin. The dosage and depth are adjustable.
The main types of injections are as follows
- intracutaneous
- subcutaneous
- Intramuscular
- intravenous
- intra-arterial
- intraosseous
- Parabulbar (solution is injected under the eyeball)
Intramuscular injections
Intramuscular injection into the deltoid muscle
Intramuscular injection is one of the most common methods of administering small amounts of medication. Muscle has a dense network of blood and lymphatic vessels that provide good conditions for drug absorption. Intramuscular injection creates a reservoir from which the drug is extracted. it is gradually absorbed into the bloodstream, keeping the blood concentration of the drug constant for several hours and ensuring a long-lasting effect.
To avoid complications, intramuscular injections are recommended in areas of the body where there is a thick layer of muscle tissue and no large vessels or nerve cords nearby. The length of the needle used depends on the thickness of the subcutaneous fat Tissue, as the injection penetrates the subcutaneous tissue and the needle must be inserted directly into the muscle. Injections are usually administered into the gluteal muscles, and less commonly into the anterior thigh muscles or deltoid muscle.
Possible complications of intramuscular injections
The following complications are possible with intramuscular injections:
- Needle penetration into a blood vessel, which can cause embolism if oily solutions or suspensions are injected that should not enter the bloodstream directly. When using such preparations, pull the plunger back into the muscle after inserting the needle and make sure there is no blood in the syringe.
- Infiltrates are painful muscle thickenings at the injection site. They may occur on the second or third day after injection. Increased sensitivity of human tissues to the injected drug (typical for oily solutions and some antibiotics)
- abscess: manifested by hyperemia, fluctuations and pain of the skin over the infiltrate, increased body temperature. It requires urgent surgical treatment and antibiotic therapy.
- Allergic reactions to the injected drug. To avoid these complications, before injecting the drug, a medical history is taken and the presence of allergic reactions to certain substances is determined. If an allergic reaction occurs (regardless of the previous form of administration), it is recommended to discontinue the drug, as re-administration of this drug may cause anaphylactic shock.
Subcutaneous Injections
Subcutaneous injection into the abdominal region with a syringe
Hematomas following injections into the abdomen
The subcutaneous fat layer has a dense vascular network, so subcutaneously injected drugs act much faster than orally injected: they bypass the digestive tract and enter the bloodstream directly, up to 2 ml diameter of the drug, which is quickly absorbed into the loose subcutaneous tissue and has no harmful effects on it.
The most suitable sites for subcutaneous injection are:
- Outer surface of the upper arm;
- Subscapular space;
- The anterolateral surface of the thigh;
- lateral surface of the abdominal wall;
- The undersurface of the axilla.
In these areas, the skin can be easily pinched into the fold, and the risk of injuring blood vessels, nerves, and periosteum is minimal.
Injections are not recommended:
- in areas of swollen subcutaneous fat;
- Ingestion of lumps from poorly absorbed previous injections is not recommended.
- The skin over the injection site is gathered into a fold, the needle is inserted into the skin at a 45° angle, and then the drug solution is gently injected into the subcutaneous fat.
Intracutaneous injection
Injecting preparations into the skin is technically not easy and requires some skill. The fine needle should penetrate only below the upper stratum corneum and not into the subcutaneous fat tissue. This is a sign that the injection has been made. Correct, it is a small bump with the preparation (so-called "lemon peel") that appears on the skin after the injection. It dissolves after a while.
Intradermal injection of preparations is mainly used in cosmetics for normalization of skin condition, but also for allergen and specific immune tests (Mantoux test, Schick reaction, etc.). Some types of local anesthetics are also administered in this way. They are usually administered on the outside of the upper and lower arm. Laypersons (people without medical training) should not administer these injections.
