Placement of an Arterial Line

Abstract

Indications Radial arterial lines are important tools in the treatment of critically ill patients. Continuous monitoring of blood pressure is indicated for patients with hemodynamic instability that requires inotropic or vasopressor medication. An arterial line allows for consistent and continuous monitoring of blood pressure to facilitate the reliable titration of supportive medications. In addition, arterial lines allow for reliable access to the arterial circulation for the measurement of arterial oxygenation and for frequent blood sampling. The placement of arterial lines is an important skill for physicians to master as they treat critically ill patients. An arterial line is also indicated for patients with significant ventilatory deficits. Measurement of the partial pressures of arterial oxygen and arterial carbon dioxide provides more information about the status of gas exchange than does arterial oxygen saturation. Contraindications The contraindications to the placement of an arterial line are few but specific. Placement of an arterial line should not compromise the circulation distal to the placement site, which means that sites with known deficiencies in collateral circulation — such as those involved in Raynaud’s phenomenon and thromboangiitis obliterans or end arteries such as the brachial artery — should be avoided. The value of the Allen test, which is used to verify collateral circulation to the hand through alternate occlusion of the radial and ulnar arteries while the hand is checked for perfusion, is somewhat controversial. Some studies have been able to demonstrate adequate perfusion with the use of other techniques that contradict the results of the Allen test. 1,2 Other contraindications include infection of the site where the catheter is to be placed and traumatic injury proximal to the proposed insertion site. Preparation There are several techniques for the placement of a radial arterial line; two of the more common are known as “over the wire” and “over the needle.” A modified Seldinger technique can also be used but is not described in this video. Preparation for both techniques is identical. The equipment needed includes a sterile preparation solution and a sterile field, a board and tape to secure and position the wrist, 1 percent lidocaine solution (without epinephrine) and a smallgauge needle and syringe for delivery, an angiographic catheter and needle, a wire if the over-the-wire technique is to be used, material such as suture or tape to secure the line once it has been placed, and a transduction system for monitoring. After the risks of the procedure have been appropriately assessed and consent has been obtained from the patient, the hand should be positioned on the wrist board. The hand should be placed in moderate dorsiflexion, which brings the artery videos in clinical medicine