Clinical meaning
Intravenous (IV) therapy involves the administration of fluids, medications, blood products, and nutritional solutions directly into the venous circulation, providing the most rapid and predictable route for systemic delivery. The practical nurse must understand the anatomy of the peripheral venous system, the principles of catheter selection, site assessment, infusion monitoring, and complication recognition to provide safe IV therapy. Peripheral IV access utilizes superficial veins of the upper extremities, with the hand, forearm, and antecubital fossa being the most common insertion sites. The cephalic vein runs along the lateral (radial) aspect of the forearm and is the preferred first-choice vein due to its large size, accessibility, and lower risk of nerve injury. The basilic vein runs along the medial (ulnar) aspect of the forearm and is an alternative, though it is closer to the brachial artery and median nerve, increasing the risk of inadvertent arterial puncture or nerve damage. The median cubital vein in the antecubital fossa is large and easily palpated, making it ideal for blood draws and short-term infusions, but it limits arm mobility and is prone to dislodgement with movement. The dorsal metacarpal veins of the hand are suitable for short-term therapy in adults but are painful to cannulate and more prone to infiltration. Site selection should consider the patient's activity level, the type and duration of therapy, the osmolarity and pH of the infusate, and patient preference. As a general rule, start distally and work proximally so that if the first site fails, the next proximal site can still be used without risk of extravasation through the previous puncture site. IV catheters are measured by gauge, with the gauge number inversely proportional to the catheter diameter: larger gauge numbers indicate smaller catheters. An 18-gauge catheter (green hub, typically) is the standard for most adult infusions and permits adequate flow rates; a 16-gauge or 14-gauge catheter is required for rapid fluid resuscitation, trauma, or blood product administration; a 20-gauge or 22-gauge catheter is appropriate for maintenance fluids, pediatric patients, or patients with small fragile veins. The flow rate through a catheter is determined by the Poiseuille equation and is proportional to the fourth power of the radius and inversely proportional to the length, meaning that a short, large-bore catheter delivers fluid much faster than a long, narrow one. Central venous catheters (CVCs) provide access to large central veins (subclavian, internal jugular, or femoral) and are used for long-term therapy, vesicant medication administration, total parenteral nutrition (TPN), hemodynamic monitoring, and when peripheral access cannot be obtained. Types of central access include non-tunneled CVCs (short-term), tunneled catheters (Hickman, Broviac), implanted ports (Port-a-Cath), and peripherally inserted central catheters (PICC lines, inserted through a peripheral vein and advanced to the superior vena cava). The practical nurse monitors peripheral IV sites regularly for complications using the phlebitis assessment scale. Phlebitis is inflammation of the vein wall and is graded from 0 (no symptoms) to 4 (pain along the venous path with palpable venous cord greater than 2.5 cm, purulent drainage, and fever). Mechanical phlebitis results from catheter movement or improper stabilization, chemical phlebitis from irritating or hyperosmolar solutions, and bacterial phlebitis from contamination. Infiltration occurs when non-vesicant IV fluid leaks into surrounding tissue, causing swelling, coolness, and pallor; it is graded from 1 (slight edema) to 4 (extensive edema with skin blanching, circulatory compromise, and moderate-to-severe pain). Extravasation is infiltration of a vesicant medication (such as certain chemotherapy agents, vasopressors, or calcium), causing tissue necrosis and requiring immediate intervention with specific antidotes. Other complications include catheter-related bloodstream infection (CRBSI), air embolism, speed shock, and catheter embolism. The practical nurse must maintain aseptic technique during all aspects of IV therapy, perform routine site assessments, flush catheters per protocol to maintain patency, and promptly recognize and report complications.