Circulation Skills 1:
Arterial and Venous Catheter Insertion
The Seldinger technique, using a guidewire to facilitate vascular cannulation, has been a great advance in emergency vascular access. Dr. Seldinger was a Swedish radiologist who began using this technique in the 1940s. Here is how it works:
- Insert a small exploring needle into an artery or vein. The kits designed for adults come with specially designed 18-gauge exploring needles. PEDS: In infants and children, use a 22 gauge cath/needle device and insert the catheter. This catheter will accept a 0.021-inch diameter guidewire. When a flashback of blood is seen, indicating that the needle or catheter is in the lumen of the blood vessel, insert a guidewire through it. The small exploring needle can then be removed while the guidewire remains in the vessel.
- When inserting a venous catheter, use a #11 scalpel to make a small skin incision on the guidewire to ease the insertion of the larger dilator/catheter. A skin incision is not needed for the insertion of an arterial catheter.
- Place a dilator/catheter over the guidewire. The guidewire must protrude from the hub of the dilator/catheter so that you can hold it while the dilator/catheter is twisted and pushed into the blood vessel. If this is not done, the guidewire will be an embolus to the heart and lungs.
- Insert the dilator/catheter to its hub. Remove the guidewire and the dilator as one, leaving the catheter in the blood vessel. Connect the catheter to the IV or arterial line prepared for connection. Flush the tubing, taking care not to introduce air. Secure the catheter with suture or tape it firmly in place.
A Rapid Infusion Catheter
(RIC) set (Arrow, Int. or Cook Co.).
A 7 French and an 8.5 French introducer are shown.
In a typical scenario, a patient with poor veins has a 20-gauge IV in place. The patient needs volume resuscitation, and the 20-gauge IV will not suffice. Rapid Infusion Catheters (RIC) are available in several sizes. Pick one appropriate to the patient and use the 20-gauge IV as the exploring needle previously described. Insert the kit's guidewire through it and, following the previous steps, replace the 20-gauge IV with a larger catheter.
PEDS: In another common scenario, an infant is dehydrated and only tiny veins can be seen. Start a 22-gauge cath/needle into the small vessel. Even though no flashback is seen, continue insertion until the hub of the needle is at the skin. Remove the needle and slowly pull back the catheter. Many times, a flashback of blood will occur, indicating that the needle had gone through the vein. Now insert a 0.021-inch guidewire into the catheter and a short distance into the vein. Push the catheter into the vein and remove the guidewire.
When percutaneous peripheral venous access is not possible, consider venous cutdown. In some cases, the saphenous vein at the ankle is a good choice.
The saphenous vein is a large, tough-walled vessel located just anterior to the medial malleolus of the ankle. Make a transverse incision over the vein and use a mosquito forcep to clear the subcutaneous tissue over it, bringing it into clear view. Insert the exploring needle into the saphenous vein. Pass a guidewire into the vein and insert a large bore catheter into the vein over the guidewire as described.
In another scenario, systemic blood pressure is not being reliably determined or arterial blood is needed frequently for blood gas determinations. Palpate the radial artery at the wrist. The femoral artery at the groin may be used, but sterility may be difficult to maintain. Insert an exploring needle into the artery selected with the return of arterial blood. Follow the previous steps to insert an arterial line into the artery. Arterial lines do not require a skin incision, nor do they need a dilator.
When the radial pulse cannot be palpated, make a skin incision over it. The procedure is greatly facilitated by using an arm board with a block under the wrist and the hand held in extension with tape or an arm board with built-in wrist extension. Pump up the cart so that the arm is at a comfortable working level. Swab the wrist with povidone solution. Preserve sterility by applying a stick-on, 2.5 inch aperture drape.
- Using a #15 blade, make a vertical incision over the distal radius about one inch proximal to the flexor crease of the wrist. Carry this incision through the skin and into the subcutaneous tissues.
- Insert a curved mosquito forcep into the wound and gently spread the blades as you work toward the distal radius. You may encounter veins, tendons, and radial nerve branches. If you encounter tendon, you are too medial. Radial nerve branches are white and soft. The artery is substantive and elastic as opposed to veins that are thin walled and soft. The artery has a pink color to it. When you have found the artery, gently work your mosquito forcep under and around it.
- Using the mosquito forcep, pass a 000 silk suture around the artery. Do not tie it. Use this suture to apply distal traction.
- Insert the exploring needle of the arterial line kit into the artery, and hold it totally still while you insert the guidewire. Remove the needle.
- Place the arterial cannula over the guidewire and pull out enough guidewire to extend out of the hub of the cannula. Now pass the cannula over the guidewire into the artery using the suture for counter traction. Remove the guidewire and apply a heparinized syringe.
- Securely suture the cannula to the skin. Staple or suture the wound closed after removing the traction suture. Attach the line to the monitor and apply a dressing as just described.