Intramuscular (IM) injections deliver medication deep into muscle tissue, allowing for rapid absorption into the bloodstream. This method is commonly used for vaccines and certain drugs that require quick uptake or are not suitable for other delivery routes. While generally a straightforward procedure, individuals administering or receiving an IM injection may sometimes encounter a sensation known as “resistance.”
What Resistance Feels Like During Injection
Resistance during an intramuscular injection feels like a distinct impediment. This often includes difficulty smoothly pushing the syringe plunger, blocking medication flow. The needle might feel “stuck” or encounter a firm obstruction. Sometimes, the syringe or needle may feel like it’s bending, or unusual pressure builds. This signals the needle’s path or medication flow is not proceeding as expected.
Factors Contributing to Resistance
Patient-Related Factors
Patient-related factors often include muscle tension, an unconscious reaction to anxiety or pain, making the muscle firm and difficult to penetrate. Scar tissue from previous injections or naturally dense muscle tissue can also present physical barriers to needle insertion and medication dispersion.
Technique-Related Factors
Technique-related issues are a common cause. Inserting the needle at an incorrect angle or insufficient depth might prevent it from reaching the intended muscle layer, leading to resistance. Hitting bone, particularly in individuals with less muscle mass, can cause abrupt, strong resistance. Improper site selection, such as injecting into an area with significant fat rather than muscle, can also impede flow.
Medication Characteristics
Medication characteristics also play a role. Highly viscous, or thick, medications naturally require more pressure to inject, which can feel like resistance. Medications not at room temperature might also be more difficult to administer due to altered viscosity.
Equipment-Related Issues
Equipment-related issues can cause resistance. Using a needle with too small a gauge for the medication’s viscosity makes it harder to push fluid. For example, highly viscous medications may require an 18- to 21-gauge needle, while less viscous solutions can use a 20- to 25-gauge needle. A faulty syringe or a dulled or bent needle can also create unexpected resistance during the injection process.
Immediate Actions When Resistance Occurs
When resistance occurs during an IM injection, stopping the injection immediately is important for patient safety. Assess the situation by observing the patient for discomfort or muscle tensing, and check the needle for any visible bending or obstruction. If the needle is not fully inserted or the angle seems incorrect, slightly withdraw it (but do not completely remove it) and re-angle.
Applying gentle, steady pressure can sometimes overcome minor resistance, but never force the injection if significant resistance persists. Forcing an injection can cause pain, tissue damage, or improper medication delivery. If resistance continues or patient discomfort arises, consider a different injection site or use a new, sterile needle and syringe. If unsure about the cause or how to proceed, seeking professional guidance from a healthcare provider is recommended.
Strategies to Minimize Resistance
Proactive strategies can minimize resistance during intramuscular injections. Proper technique is fundamental, including selecting the correct needle length and gauge appropriate for the patient’s size, injection site, and medication viscosity. The needle should be inserted at a 90-degree angle to ensure it reaches the muscle.
Careful site selection and rotation are important to avoid scar tissue or excessive fat, and to allow previous injection sites to heal. Encouraging the patient to relax the muscle receiving the injection, possibly through deep breathing exercises or distraction, can reduce muscle tension. Allowing viscous medications to reach room temperature before administration can also reduce their thickness, making them easier to inject. Finally, always ensure the needle is sharp and intact before use, as a damaged needle can increase resistance.