Other HESI Final Study Guide HESI Final Study Guide Medication Calculations (IM, mg and mL, IVgtt/min) Review: All oral and Injectable calculations; conversion methods for weights and temperatures Intramuscular Injection (IM): Injection into a muscle Intradermal (ID): Injection into the dermis just under the epidermis Subcutaneous: Injection into tissue just below the dermis of the skin Intravenous (IV): Injection into a vein PRN: As needed. When administering medications, document the assessm...