Comprehensive Guide to Peripheral Venous Catheterization

Introduction and Objectives of Peripheral Venous Catheterization

Peripheral venous catheterization is a clinical procedure primarily aimed at canalizing a peripheral vein to facilitate the administration of fluid therapy and/or medication. These interventions are performed with various clinical goals, including diagnostic or therapeutic purposes. The procedure ensures a reliable route for administering essential fluids and pharmacological agents directly into the circulatory system.

Essential Materials and Equipment

A wide array of specialized materials is required to perform a safe and effective peripheral venous catheterization. This includes the specific solution to be perfused or the pharmacological agent to be administered. The intravenous peripheral (IVP) catheter itself is central to the kit. For site preparation, antiseptics such as Alcohol or Chlorhexidine at a concentration of $2\%$ are utilized. A complete perfusion system is necessary to deliver the fluids, which is often regulated by an infusion pump and supported by an IV pole or support stand (soporte de suero).

Additional accessories for the management of the line include a three-way stopcock (llave de tres vías) and a sterile cap (tapón estéril). Securement is achieved using specific materials and adhesives, such as 3M adhesive tape (cinta adhesiva 3M). Finally, safety and hygiene are maintained through the use of a biohazard waste container (contenedor de residuos biopeligrosos) for the disposal of contaminated materials and sharps.

Anatomical Components of the Catheter

Understanding the design of the peripheral catheter is vital for successful insertion. The device consists of a protective sleeve (funda protectora) that covers the needle and catheter before use. The internal structure includes a stylet or needle, referred to as the fiador, which provides the rigidity necessary to puncture the skin and vein. The catheter itself is a flexible tube that remains in the vein. Key handling parts include the support tab (lengüeta de apoyo), which allows the practitioner to manipulate the device, and the catheter hub or connection cone (cono de conexión del catéter) where the perfusion system is attached. At the proximal end, there is a rear chamber (cámara trasera) where blood reflux is observed to confirm successful entry into the vein.

Catheter Gauges, Indications, and Infusion Rates

The choice of catheter gauge ($G$) is determined by the patient's clinical state and the required volume of infusion. Each gauge is associated with specific maximum infusion volumes:

Catheter Gauge 24: Indicated for continuous infusions, bolus administration, or intermittent medications. It allows for a maximum infusion volume of $16-24\,ml/min$.

Catheter Gauge 22: Suitable for the majority of general treatments, including blood transfusions. It allows for a maximum infusion volume of $27-36\,ml/min$.

Catheter Gauge 20: Typically used for relatively stable patients requiring infusions of viscous liquids, packed red blood cells (concentrado de hematíes), or rapid perfusion of large quantities of fluids. It allows for a maximum infusion volume of $49-63\,ml/min$.

Catheter Gauge 18: Reserved for patients in critical conditions such as shock, post-traumatic scenarios, and complex surgeries. It allows for a high maximum infusion volume of $85-104\,ml/min$.

Vein Selection and Initial Preparation

Selecting the appropriate vein is critical for the longevity and functionality of the access point. Common veins targeted for peripheral access include the cephalic vein, the accessory cephalic vein, and the saphenous vein. The initial procedure begins with thorough hand washing and the preparation of all materials, including the priming (purgar) of the perfusion system to remove air. Once the vein is selected, the practitioner applies securement and hemostasis (often via a tourniquet). It is vital to choose a catheter with a smaller gauge (diameter) than the selected vein to prevent irritation. If necessary, a trichotomy (hair removal) is performed at the site.

Clinical Procedure for Insertion

The insertion process begins with disinfecting the puncture site using the chosen antiseptic. The needle is inserted at an appropriate angle of approximately $25^\circ$. Once the skin is breached, the catheter is advanced while holding the stylet (fiador) steady. The practitioner must check for blood reflux in the rear chamber to confirm that the vein has been successfully entered. Upon confirmation, the tip of the stylet is slightly withdrawn, and the catheter is slid over the stylet until it is fully canalized within the vein.

Following successful placement, the compressor/tourniquet is removed, and the stylet is completely withdrawn from the catheter. The team must verify the correct canalization of the vein before connecting the perfusion equipment. Once connected, the drip rate (ritmo de goteo) is adjusted according to the medical orders. The insertion area is cleaned and disinfected again, and the short catheter is fixed in place with adhesive strips. The practitioner then verifies that the perfusion is flowing properly, organizes and cleans the workspace, and establishes a maintenance plan for the line.

Potential Complications

Practitioners must remain vigilant for complications that can arise during or after the catheterization process. Common issues include extravasation (the leakage of fluid into surrounding tissues) and inflammatory conditions like phlebitis or thrombophlebitis. Serious systemic risks include sepsis and air embolism (embolismo aéreo). There is also a risk of embolism caused by the sectioning of the catheter. Localized issues can also occur, such as hemorrhage at the site, accidental removal or avulsion (arrancamientos) of the catheter, and internal obstruction of the line.