As intramuscular injection (shorthand notation: in ) refers to the introduction of a liquid medicament in a skeletal muscle using a syringe and needle or syringe. The intramuscular injection is thus a parenteral form of administration. It is used to administer drugs by bypassing the gastrointestinal tract with a certain depot effect (e.g. hormone preparations, antipsychotics , antibiotics ). In human medicine, intramuscular injection is also used for most vaccinations , while in veterinary medicine - at least for small animals - vaccination is mainly subcutaneous .
- Shock : due to the centralization of the circulatory system, the absorption in the muscles is greatly slowed down
- If an acute myocardial infarction is suspected , the creatine kinase , which increases with intramuscular injections, can be mistakenly understood as a sign of myocardial infarction, which today, however, only plays a subordinate role due to the determination of cardiac troponins . In the event of an actual infarction or pulmonary embolism, an intravenous injection precludes lysis therapy (risk of hematoma formation ).
- Hemorrhagic diathesis : e.g. B. in hemophilia , can lead to bleeding and hematoma formation.
- Oral administration of anticoagulants: z. B. Phenprocoumon , can lead to massive hematoma formation.
- Heparin therapy : also risk of bleeding or hematoma formation
Capability of intramuscular injection
The intramuscular injection is primarily one of the medical and medical practice areas. The doctor can transfer this task to nurses or medical assistants, provided that he is convinced of their implementation skills. In addition to the responsibility for arranging the injection itself (responsibility for arranging the injection), he is also always responsible for delegation. Whoever ultimately takes on and carries out the task is responsible for ensuring that this is done properly, i.e. with the usual care (implementation responsibility).
In addition, the respective institution (e.g. represented by a board of directors) is responsible for the framework conditions under which e.g. B. an injection can be carried out properly at all (organizational responsibility). One speaks here of structure quality. This includes, for example, the provision of the necessary needles and syringes, the sufficient number of staff, the provision of training courses, etc.
The competence to inject intramuscularly is demonstrated in medical studies, in training to become a naturopath and among others. a. Acquired in the three-year professional training to become a health and nurse, geriatric nurse, emergency paramedic, medical assistant or midwife.
An injection is invasive . It constitutes bodily harm and is therefore punishable unless the patient has given his consent. This can also be done tacitly, for example by clearing his buttocks and turning to the side. In addition, an injection to which the patient cannot consent, but which presumably corresponds to his will, for example for the treatment of an acutely life-threatening illness, is not punishable. The patient is to be informed about the purpose, side effects and complications of an injection (medical task). If the doctor does not inject himself, he has to select a competent vicarious agent . Arrangement, clarification and implementation as well as any complications / incidents must be documented promptly. It is documented by the person who injected and / or observed. What has not been documented must legally be considered not carried out. In the event of a dispute, incomplete documentation can result in a reversal of the burden of proof.
For injectors in particular, the following is particularly careful:
- Observe the six-R rule
- Right patient
- Correct medication (including checking for shelf life with visual inspection)
- Right dose
- Correct application form
- The right moment
- Correct documentation
- Proper search for the injection site
- Professional selection of the cannula size
- Professional selection of the syringe size
- Hygienic working
- Aspiration before injection
- Recognizing possible complications and responding appropriately
Injection sites in humans
In humans, the buttocks, upper arm and thigh are suitable injection sites.
The injection into the buttocks is made into the gluteus medius and gluteus minimus muscles (intragluteal / intragluteal). The injection volume is limited to 10 ml. This muscle is not suitable for patients under the age of 2, as not enough muscle mass has yet been built up.
In this area in particular, it is of the utmost importance to strictly adhere to the methodology described. A deviation, such as the quadrant method carried out earlier, may, among other things. a. cause injury to the sciatic nerve or incorrect injections into blood vessels.
Ventrogluteal injection according to Arthur von Hochstetter
Ideally, the patient lies on their side, facing away from the injector. However, the method can also be used in the supine position. One oath finger (index or middle finger, depending on the position) lies on the anterior superior iliac spine, the second oath finger now glides approx. 5 cm along the iliac crest. In slim patients, the iliac tuberosity can then be felt. While the first oath finger remains on the spine, the second (dorsal) is moved a few centimeters down so that the heel of the hand comes to rest on the greater trochanter. The injection is made in the lower half of the triangle between the two swell fingers perpendicular to the body surface.
Practice shows that tendinous tissue can often still be felt at the correct injection site. In this case, contrary to Hochstetter, it is recommended to inject 2 to 3 cm further dorsally. The distance to large vessels and nerves is still maintained. There is no need to differentiate which hand is to be used for which side of the body, as Hochstetter describes occasionally.
Ventrogluteal injection according to Peter Sachtleben (Crista method)
Bony landmarks are the iliac crest (iliac crest) and the greater trochanter (large rolling hillock).
Ideally, the patient lies on their side. One hand is placed on the hip in such a way that the edge of the index finger lies against the iliac crest from above (cranial). In patients> 150 cm in height , the injection is made at a distance of three transverse fingers below the edge of the index finger perpendicular to the body surface, in patients between 100 and 150 cm in height at a distance of two transverse fingers below the edge of the index finger and in patients <100 cm in height at a distance of one cross finger below the edge of the index finger perpendicular to the body surface.
The indication of the number of cross fingers below the edge of the index finger is not yet a clear indication of the injection site. Therefore, the vertical line through the greater trochanter is used as a further orientation line, so that the injection takes place laterally and not dorsally. If the ventrogluteal injection is mandatory, the Crista method is a must for patients less than 150 cm tall, while it is only an alternative to the Hochstetter method for larger patients. It should also be noted that the ventrogluteal injection is generally only recommended from the age of two (see above).
Other injection techniques
In practice, the injection techniques according to Dvorák and Fortmann are practically irrelevant today.
The injection into the thigh is into the quadriceps femoris muscle (more precisely: vastus lateralis muscle ). The injection volume is limited to 5 ml. Oily or corticosteroid solutions, antibiotics and anti-inflammatory drugs should not be injected. This muscle is the first choice for patients under 2 years of age.
Method according to Arthur von Hochstetter
The patient should ideally lie on their back, but an injection in a lateral position is also possible. The metatarsophalangeal joints of the little finger lie on the kneecap and the greater trochanter. The thumbs spread at right angles can now easily feel the lower (dorsal) limitation of the vastus lateralis muscle. The injection is made in a field above the two thumb tips vertically in the direction of the thigh bone.
As an alternative or obligatory for children due to the changed body proportions, the injection site is in the middle third of the (oblique) connecting line between the greater trochanter and the kneecap.
The injection is made into the deltoid muscle on the upper arm . The injection amount is limited to two milliliters due to the low muscle mass. Aggressive drugs that are difficult to absorb should be avoided here. This muscle is the first choice for vaccinations. The acromion (shoulder height) serves as a bony orientation point .
The patient is sitting or standing, but an injection in a lateral position is also possible. The injection is made into the main mass of the deltoid muscle, three transverse fingers below the acromion perpendicular to the skin surface.
The length of the cannula is of particular importance for intramuscular injections. Cannulas with a length of 25 to 70 mm are used. A cannula that is too long can hit bone tissue, and a cannula that is too short can land in the subcutaneous fat tissue instead of in the muscle, especially in obese patients, but also in people of normal weight. An incorrect injection into adipose tissue not only leads to an altered absorption time, but can also result in serious complications (see below).
The specialist literature usually recommends not to pierce the cannula all the way, but rather to keep a distance of 10 mm between the cone and the skin. The reason given is that if the cannula breaks, it can still be pulled out without any problems. However, if the injection is performed properly, breaking a cannula is a rare complication.
An aspiration attempt should always be performed prior to an intramuscular injection. If blood is aspirated in the process, the procedure must be interrupted, the drug must be drawn up again with a new syringe and cannula and injected elsewhere. Blood drawn in is a sign that a blood vessel has been punctured and that the injection would therefore also be made into this vessel (intravenously or intraarterially) and not, as desired, into the muscle tissue. Complications could result. In order to avoid an injection into the vessel wall, the cannula should be rotated again by 180 ° so that an intravascular position is definitely excluded.
- Aseptic spray abscess
- Septic syringe abscess
- Muscle fibrosis
- Aseptic muscle necrosis
- Adipose tissue atrophy
- Calcifications of muscle or fat tissue
- Nerve damage
- Pulmonary embolism
- Cerebral microembolism
- Embolia cutis medicamentosa (with Nicolau syndrome)
While some complications cannot be controlled (e.g. calcifications), the majority of incidents with intramuscular injection are due to improper execution. Sources of error lurk especially when looking for the injection site, when selecting the cannula, when injecting itself (forgotten aspiration) and when performing asepsis.
- H. Humbert: Injections and blood withdrawals . 1st edition. W. Kohlhammer, Stuttgart 2002
- intramuscular . Duden online. There as an abbreviation i. m. according to general typographical rules; The notation im without spaces is also common .