Intravenous Cannulas: Types and its applications

Cannulas are most commonly used in hospitals to administer medication & contrast media or dyes, drain bodily fluid and supply oxygen to the body.

  • 1. IV cannula: IV cannula is a flexible tube attached to a retractable needle inserted into the vein for administering medication.

  • 2. Nasal cannula: The nasal cannula is used for oxygen supply through a thin hollow tube to the body via the nasal cavity.

Basic diagram of IV cannula

There are two types of IV cannulas

  • 1. Peripheral IV cannula: Injected in a vein located at the extremities/limbs of the body

  • 2. Central line IV cannula: Injected into major vein stems of the body

Choice of site for IV cannulation

Cannulation should be done in such a location that it remains for a longer time without causing any discomfort to the patient. Occlusion is found to be one of the most common reasons for cannula failure. Thus, flexion of that area is important for the performance of the cannula. Therefore, cephalic or basilic veins on the forearm or dorsal metacarpal veins on the back of the hand are considered to be appropriate for IV cannulation.

Unlike peripheral IV cannulation, the central IV line is injected to major veins of the body like jugular vein, femoral vein, or axillary vein. Central IV lines remains for a longer period of time than peripheral IV lines

Sizes and color codes

Color codes of the IV cannulas are as per their sizes. The overall size of the cannula is dependent on the needle gauge, external diameter, length of the cannula and flow rate. As the gauge size increases, the diameter of the bore of the cannula decreases so does

the flow rate of the fluid. The sizes of the cannulas range from 14G to 24G. The size is selected according to the intended use, age and condition of the patient.

Commonly available variants in IV cannula:

IV Cannula fixator

There are two types of fixators available for IV cannula so that the canula is fixed firmly on the site without any kind of leakage or accidental removal.

  • Dynaplast fixator

  • Transparent fixator

Safety of the patient and clinician

Usage of gloves while performing cannulation is beneficial for the clinicians to prevent themselves from being infected from blood borne pathogens.

As for the patients, the risk of insertion of foreign materials and resulting complications such as extravasation (cannula entering the tissue instead of vein causing swelling), embolism (artery obstruction by a clot/air bubble), haematoma (solid swelling of clotted blood within the tissue), thrombophlebitis (venous thrombosis), and artery puncturing. must be considered.

Thus, proper precaution must be taken while performing cannulation to avoid any type of risks and hazards