What is Cannula?

A cannula is a small tube inserted into a body cavity, duct, or vessel for medical purposes. There are two main types of cannulas: intravenous (IV) and nasal. IV cannulas consist of short, flexible tubing inserted into a vein, commonly used for blood transfusions, blood draws, medication administration, and fluid delivery. Nasal cannulas, on the other hand, are designed to deliver oxygen through a flexible tube with two prongs that fit into the nostrils. They are particularly useful for individuals experiencing difficulty breathing, as they reduce the effort required to breathe and alleviate strain on the heart, effectively treating hypoxia or hypoxemia.

Where is Cannula used? Why do people need cannulas?

The purpose of a cannula varies depending on its type.

IV Cannula: IV cannulas are typically used for:

• Blood transfusions or draws
• Administering medication
• Providing fluids

Nasal Cannula: Nasal cannulas are used to provide oxygen to individuals with breathing difficulties. According to UTMB Respiratory Care Services, nasal cannulas help to:

• Reduce the effort needed to breathe
• Alleviate strain on the heart
• Treat hypoxia or hypoxemia

What are the different Types of Cannula?

Types of IV Cannulas

IV cannulas come in different types and sizes to suit various medical needs here are also several sizes of intravenous cannulas. The most common sizes range from 14 to 22 gauge. The higher the gauge number, the smaller the cannula. Different sized cannulas move liquid through them at different rates.

Peripheral IV Cannulas:

Used in emergency rooms and surgeries for short-term purposes. Administer fluids or contrast for imaging procedures. Secured with tape to prevent displacement.

Central IV Cannulas:

Employed for long-term treatments requiring extended IV medication or fluids. Commonly used in chemotherapy for drug infusion. Inserted into major veins like the jugular, femoral, or subclavian, enabling rapid medication delivery. Prone to infection; promptly removed if signs such as erythema, swelling, or fever develop.

Draining Cannulas: Utilized to remove fluids or substances from the body. Essential in critical conditions like ECMO for severe pulmonary or cardiac failure. In ECMO, blood is withdrawn, oxygenated, and returned to the body. Also employed in procedures such as liposuction, connected to a trocar for fluid manipulation within body cavities or organs.

Types of Nasal Cannulas:

Standard Nasal Cannula: A standard nasal cannula consists of lightweight plastic tubing inserted just inside the nostrils. It provides supplemental oxygen at a lower flow rate compared to high-flow nasal cannulas (HFNC). Suitable for all age groups, it allows breathing through the mouth or nose and is appropriate for both short-term and long-term use. Sizes are available for adults, children, and infants. Oxygen delivery varies based on breathing rate and depth, with flow rates typically up to 4–6 liters per minute. At higher flow rates, a humidifier may be recommended to prevent drying of nasal and oral mucous membranes.

High-Flow Nasal Cannula (HFNC): HFNC systems deliver oxygen at significantly higher flow rates, up to 60 liters per minute. The gas is heated to body temperature (98.6°F or 37°C) for comfort and to reduce airway irritation. HFNCs are preferred by some individuals for their lighter feel and reduced airway irritation compared to standard nasal cannulas. They have proven effective, especially during respiratory distress such as in COVID-19 cases.

At-Home Nasal Cannulas: Portable nasal cannulas allow individuals to receive oxygen therapy at home. Similar to hospital settings, they connect to a portable oxygen supply. Healthcare providers instruct users on equipment usage and oxygen refill schedules to ensure effective home oxygen therapy.

What are the benefits of using cannulas over needles?

• Cannulas offer reduced tissue trauma compared to needles, leading to less pain and discomfort during insertion and prolonged use.
• They lower the risk of complications such as nerve damage, arterial punctures, and tissue bruising.
• Cannulas allow for longer-term access for medications, fluids, or blood draws, minimizing the need for repeated insertions.
• Patients benefit from improved comfort and mobility, particularly in long-term treatments like chemotherapy or intravenous therapies.
• Cannulas serve multiple medical purposes beyond intravenous access, including oxygen delivery and fluid drainage in various clinical procedures.

How to choose the right cannula?

• Check for Appropriate Size: Use the smallest and shortest cannula suitable for the procedure to minimize complications associated with vein size. Larger cannulas increase the risk of complications.
• Consider Infusate Factors: Select cannula size based on factors like drug osmolarity, pH, and viscosity. Smaller diameters are suitable for lower arm veins, while larger diameters may be needed for upper arm veins.
• Gauge Size Explanation: Cannula sizes are designated by gauge, where lower numbers indicate larger diameters. For instance, an 18g cannula has a larger diameter than a 24g cannula.
• Flow Rate and Length: Flow rates through cannulas depend on internal diameter, inversely proportional to length. Longer cannulas may increase the risk of vascular complications like phlebitis.
• Quality Control and Ports: Ensure cannulas come from reputable suppliers with rigorous quality control measures. Cannulas with ports allow drug administration without disrupting infusions, but proper cap replacement is crucial to avoid contamination.

Cannula Specifications- IV Cannula Colour Coding | IV Cannula Size & Flow Rate:

What are the Applications Cannulas?

Intravenous Therapy: Cannulas are primarily used for intravenous therapy, delivering fluids, electrolytes, medications, and blood products directly into the bloodstream. This method ensures safe and efficient administration, crucial in emergency medical care.

Oxygen Delivery: Nasal cannulas are essential for delivering supplemental oxygen to patients with respiratory conditions like COPD or acute respiratory distress. They provide a controlled flow of oxygen to support lung function effectively.

Anesthesia and Surgery: Venous and arterial cannulas are vital in anesthesia induction and for continuous monitoring of blood pressure, oxygen levels, and blood gases during surgery. They help anesthesiologists maintain patient stability throughout procedures.

Blood Sampling: Arterial cannulas facilitate arterial blood sampling, enabling healthcare providers to assess blood gas levels. This diagnostic tool is critical in managing respiratory and metabolic disorders.

Chemotherapy: Intravenous cannulas are crucial in chemotherapy treatments, ensuring the safe and effective delivery of potent drugs while minimizing complications for cancer patients.

Parenteral Nutrition: For patients unable to receive nutrients orally, parenteral nutrition involves intravenous delivery of essential nutrients. Specialized IV cannulas are used to provide vital nutrition directly into the bloodstream.

Difference between cannula and catheter:

Feature	Cannula	Catheter
Purpose and Function	Primarily for IV therapy, oxygen delivery, blood sampling	Used for drainage, administration of fluids, surgical access
Design and Structure	Smaller, simpler, various sizes and configurations	Longer, flexible, specialized designs for specific medical uses
Applications	IV therapy, oxygen therapy, anesthesia, blood sampling	Urinary catheterization, central venous access, cardiac catheterization
Insertion and Removal	Temporarily inserted into veins or arteries, easily removed	Often left in place longer-term, more complex insertion and removal
Medical Uses	Emergency medicine, surgery, critical care, routine treatments	Urology, cardiology, radiology, surgical procedures

Tips while using cannula:

• Before using a cannula, inspect it for any defects or damage. Ensure the tubing is kink-free and the connectors are secure.
• Use the appropriate size cannula for the patient and the intended therapy. Ensure the cannula fits comfortably without causing undue pressure or discomfort.
• Ensure the cannula is securely taped or secured to the patient's skin to prevent accidental dislodgement.
• Regularly check the skin around the cannula insertion site for signs of irritation, redness, or breakdown. Adjust placement if necessary to prevent skin damage.
• Ensure the cannula remains patent (open) by flushing it with saline or according to medical protocol. This prevents blockages and ensures effective therapy delivery.
• Educate patients (or caregivers) on proper care and maintenance of the cannula, including signs of complications like infection or blockage.
• Maintain strict hygiene practices when handling and inserting cannulas to minimize the risk of infection. Use sterile techniques as recommended.
• Follow guidelines for replacing cannulas to prevent infection and ensure optimal performance. Replace as recommended by healthcare providers or manufacturer instructions.
• Ensure the cannula is positioned comfortably for the patient, particularly in areas prone to movement (e.g., arms). Avoid placing unnecessary tension on the tubing.
• Be prepared for emergencies by having spare cannulas and equipment readily available. Know how to respond to cannula-related complications promptly.