Intramuscular (IM) injections deliver medication deep into muscle tissue for rapid absorption into the bloodstream. This method is used for vaccines, antibiotics, and other treatments requiring quick onset or unsuitable for oral administration. While generally effective, incorrect administration can lead to complications. This article explores the potential outcomes of improper IM injection.
Fundamentals of Intramuscular Injection
Correct IM injections target specific muscles chosen for their size, vascularity, and distance from major nerves and blood vessels. Common sites include the deltoid in the upper arm, the vastus lateralis in the thigh, and the ventrogluteal area on the hip. The deltoid is often used for smaller volume injections like vaccines. The vastus lateralis is preferred for infants and children, while the ventrogluteal site is safe for adults due to its thick muscle mass and minimal nerve proximity.
Proper technique involves inserting the needle at a 90-degree angle to reach the muscle layer. Needle length is selected based on patient age, weight, and muscle mass, typically 1 to 1.5 inches for adults. This ensures correct medication deposition within the muscle for efficient absorption.
Types of Administration Errors
Errors in IM injection administration can lead to undesirable outcomes. Incorrect site selection is a common mistake, where the injection is given in an area lacking sufficient muscle mass or too close to sensitive structures. For example, injecting too high or low in the deltoid can cause shoulder issues. Improper placement in the gluteal region, especially the dorsogluteal site, increases the risk of hitting the sciatic nerve or major blood vessels.
Incorrect needle depth is another error. A shallow needle may deposit medication into subcutaneous fat instead of muscle. Inserting the needle too deeply can hit bone. Accidental contact with or injection into a nerve, like the sciatic nerve, is a concern, as is puncturing a blood vessel, which can lead to medication entering the bloodstream directly.
Improper technique also contributes to errors. Injecting medication too rapidly can cause increased pain or discomfort. While aspiration (checking for blood) was once common, current guidelines for many vaccines no longer recommend it.
Potential Complications of Incorrect Injection
Incorrect IM injection can lead to various complications affecting patient comfort and health.
Nerve Damage
Nerve damage is a concern, particularly with injuries to the sciatic nerve in the buttock or the radial nerve in the arm. Symptoms of nerve injury can include sharp pain, burning sensations, numbness, tingling, muscle weakness, or even temporary or permanent paralysis in the affected limb. In some cases, foot drop, an inability to lift the front part of the foot, can occur due to sciatic nerve damage.
Vascular Injury
Vascular injury can result from the needle puncturing a blood vessel. This may lead to the formation of a hematoma, which is a collection of blood outside blood vessels, appearing as bruising and swelling. Accidental intravascular injection, where the medication enters the bloodstream directly, can cause rapid systemic effects or adverse drug reactions, as the drug bypasses its intended slow absorption.
Bone Contact
Contact with bone during injection can cause intense pain. It may also lead to damage or inflammation of the periosteum, the membrane covering the bone. In some instances, bone infections like osteomyelitis have been reported.
Subcutaneous Injection
Injecting medication into the subcutaneous tissue rather than the muscle can result in poor or delayed absorption of the drug, reducing its effectiveness. This misplacement can also cause localized pain, swelling, redness, and irritation at the injection site. A sterile abscess, a collection of pus-like fluid without bacterial infection, can form due to the medication not being designed for subcutaneous delivery. Tissue necrosis, or tissue death, can also occur if certain substances are injected subcutaneously.
Infection and Abscess
Infection and abscess formation are potential complications. While often linked to poor sterile technique, tissue damage or repeated injection attempts from incorrect administration can increase susceptibility to localized bacterial infections. These infections can manifest as redness, warmth, swelling, and the presence of pus at the injection site. A localized infection can progress to a widespread systemic infection known as sepsis.
General Pain and Inflammation
General pain and inflammation are common consequences of any injection error. This can range from acute discomfort and swelling to more prolonged issues. Shoulder Injury Related to Vaccine Administration (SIRVA) is a specific type of pain and inflammation that can occur when a vaccine is injected too high into the deltoid muscle, potentially affecting the bursa or rotator cuff. This can result in chronic pain, limited range of motion, and persistent inflammation.
Recognizing and Addressing Complications
Recognizing signs of an incorrectly administered IM injection is important for timely intervention. While mild soreness is normal, persistent severe pain, especially sharp or radiating pain, should be noted. Other warning signs include numbness, tingling, or weakness in the affected limb, indicating nerve involvement. Excessive bleeding or a rapidly expanding hematoma at the injection site also warrants attention.
Signs of infection include increasing redness, warmth, swelling, or pus-like discharge from the injection site. Fatigue, fever, or headaches following an injection can signal a widespread issue. If any concerning symptoms appear or persist, seek medical attention. A healthcare professional can assess the injury and determine the appropriate course of action, including diagnostic tests or specific treatments. Applying cold compresses may provide initial relief, but this should not replace professional medical evaluation for concerning or worsening symptoms.