An IV cannula and tube.
Cannulas – or flexible tubes that can be inserted into the patient’s body – are used for different purposes, resulting in cannula sizes ranging from 14-22 gauge. Intravenous cannulas are used to administer drugs and other fluids to patients and to remove blood for sampling. The purpose, the patient’s condition, and the urgency with which the intravenous fluid must be administered determine which cannula sizes should be used. The smaller the gauge, the larger the diameter of the cannula and the faster the flow of fluid. Different cannula sizes are indicated by different colors, making them easier to differentiate, especially in emergency situations where size can be critical.
IV cannulas are used to administer medications and other fluids to patients.
A blue colored cannula indicates a 22 gauge, which allows for a fluid flow rate of 36 milliliters per minute. This cannula size is often used in children because of their small size and in patients with veins that are difficult to cannulate, including the elderly and cancer patients. These cannulas are usually only used to infuse normal saline, antibiotics, and anticoagulant medications such as heparin.
A cannula can be used for intravenous feeding of a patient with bulimia.
The standard cannula for routine use is pink. A 20 gauge cannula has a fluid flow rate of 61 milliliters per minute. This cannula size is primarily used for routine blood collection, but can also be used for routine blood transfusions and intravenous fluid infusions. Green cannulas are also considered standard size. Measuring as an 18 gauge, with a fluid flow rate of 90 milliliters per minute, this cannula size is used for routine blood transfusions, transfusion of large volumes of fluid, intravenous feeding of patients, and cell collection and separation. trunk .
Elderly patients may require a smaller cannula size.
The white colored cannula size is rarely used. A 17 gauge cannula has a fluid flow rate of 140 milliliters per minute. Cases where this cannula size can be used include patients who need significant amounts of intravenous fluids or for blood transfusions which, while not emergency, need to be given as soon as possible.
Emergency situations and operating rooms tend to use gray and brown cannulas. Gray colored cannulas have a 16 gauge size and a fluid flow rate of 200 milliliters per minute, and 14 gauge brown colored cannulas have a flow rate of 300 milliliters per minute. These larger cannula sizes are needed for rapid transfusion of blood, IV fluids, and medications.
An 18 gauge cannula is used for routine blood transfusions.
Choosing the correct size of cannula is important so that treatments can be performed properly. For example, smaller cannula sizes result in greater pressure in the vein. This can cause hemolysis during aspiration of a blood sample if the cannula is too small. Also, if a patient needs a bolus or rapid infusion of medication, a cannula that is too small will not allow the fluid to flow quickly enough and, combined with the increased pressure, can result in the vein leaking.