Author:
Kai Knudsen
Updated:
1 April, 2025
Peripheral venous catheters (PVCs) are fundamental for vascular access, providing a means to administer fluids and medications rapidly and safely. Typically, PVCs are placed in a superficial subcutaneous vein on the dorsum of the hand or in the antecubital fossa. They are also used for blood transfusions and continuous infusion of vasoactive drugs, nutritional solutions, and intravenous anesthetics. PVCs are commonly referred to as "Venflon."
Peripheral Venous Catheter (PVC)
A PVC consists of a plastic cannula with a stylet inside. The stylet is a sharp metal needle inside the cannula that is withdrawn immediately after positioning the plastic cannula in the vein. Some PVCs have a protective cover that occludes and protects against needle sticks after the metal stylet is removed (needle stick protection). Some PVCs (such as Venflon) have a valve housing (“chimney”) on the base of the cannula for venous injections, while others allow injections only through the proximal end of the cannula.
Today, PVCs are always sterile, single-use plastic cannulas with a metal stylet. For awake patients with stable vital signs, a peripheral venous catheter of 0.9-1.3 mm in diameter (blue-pink-green) is usually sufficient. The color and dimensions may vary depending on the manufacturer. A PVC should not remain in the same vein for more than a few days and should be checked daily for cleanliness, leakage, or infections. For critically ill patients, at least two PVCs should be inserted, and for patients with trauma or significant bleeding, at least three PVCs should be inserted, with at least two being large-bore.
Typically, a PVC is inserted without anesthesia in sizes ranging from 0.9 to 1.5 mm. Children and sensitive patients may be offered “topical” anesthesia with skin-numbing patches. In sizes of 1.8-2.0 mm, local anesthesia should be administered if the patient is fully awake, not sedated, severely drowsy, or in a coma or under general anesthesia. Always operation under sterile conditions. If three attempts to insert the needle fail, it may be necessary to reassess the indication, take a break, or have another person insert the needle. Difficult-to-cannulate patients should receive help from experienced personnel, preferably an anesthesia nurse. The first attempt is usually the best chance of success. Hypovolemic patients, patients in shock, “over-cannulated patients,” and obese or overweight patients can present very challenging conditions for successful PVC insertion. Ultrasound-guided puncture can be a helpful tool in such cases.
The insertion itself is performed in two consecutive steps:
- A) Penetration through the skin but not the vessel wall
- B) Penetration through the vessel wall once the needle is under the skin.
If the patient has well-filled and visible veins, steps A and B can often be performed in one motion. However, for difficult-to-cannulate patients or those with small or barely visible veins, it is better to perform the insertion in two steps: A followed by B.
The needle’s angle against the skin at step A is steeper than at step B, which should be nearly flat. A common mistake is to have too steep an angle when penetrating the vessel wall, causing the needle tip to go underneath the vessel instead of into it. When penetrating the vessel wall, it’s important not to withdraw the stylet too early. The cannula should be advanced at least one centimeter before retracting the stylet but should not be advanced too far, as there’s a risk of passing entirely through the vessel. The cannula is secured with a specific adhesive dressing (e.g., Tegaderm), which allows inspection of the insertion site.
Veins in the arm become more filled through stasis or by lowering the arm “declining stasis.” Venous stasis can be achieved with a tourniquet or a blood pressure cuff. Heat and light tapping on the vein can also help a little.
If a PVC is needed for more than two days, it can be replaced with a midline catheter, which is inserted under sterile conditions using ultrasound into the veins of the upper arm.
Here is a summary of Peripheral Venous Catheter (PVK) sizes and their respective indications:
| Color | Size (G) | Size (mm) | Indication |
|---|---|---|---|
| Blue | 22 G | 0.9 mm | For elderly patients, children, and those with fragile or difficult veins. |
| Pink | 20 G | 1.1 mm | Common size for standard intravenous (IV) medication and hydration. |
| Green | 18 G | 1.3 mm | Used for IV medication, blood transfusions, and mild to moderate fluid resuscitation. |
| White | 17 G | 1.5 mm | For rapid infusion of fluids and blood transfusions. Suitable for surgical patients and emergency cases. |
| Gray | 16 G | 1.8 mm | For large volume blood transfusions and rapid fluid resuscitation in emergency situations. |
| Orange | 14 G | 2.0 mm | Rarely used, mostly for trauma cases or in situations requiring very fast infusion rates. |
These sizes are generally chosen based on the patient’s condition, vein quality, and the type of therapy or intervention needed.
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