9 Arterial Line

Irene Say, Celina Crisman, and Nitesh V. Patel

Abstract

Arterial lines cannulation is a common procedure in the intensive care unit (ICU). Here, the relevant anatomy, physiology, indications, technique, complications, and expert suggestions are outlined.

arterial line – blood pressure – hypertension – hypotension – radial artery – mean arterial pressure – hemodynamic stability – intensive care unit

9 Arterial Line

9.1 Introduction

Insertion of an arterial line entails the placement of a catheter in a patient’s artery, most commonly the radial artery. An arterial catheter can be used to transduce continuous blood pressure measurements and to sample arterial blood for laboratory analysis. Accurate measurement of blood pressure is not only essential for managing cardiac output and monitoring ventilation in severe pulmonary disease, but also vital in guiding neurocritical care of diseases such as intracranial hypertension, intracranial hemorrhage, neurogenic shock, and cerebral vasospasm. Unlike noninvasive means of blood pressure management (NIBP), which is only episodic, the arterial line provides continuous, real-time measurement of blood pressure and gives convenient and immediate arterial access for blood sampling. Connection of the arterial catheter to an external transducer allows for quantitative measurement of intra-arterial blood pressure and an arterial waveform, representing the systolic and diastolic pulsations of the circulatory system. A typical arterial line schematic and radial artery anatomy are demonstrated in ▶ Fig. 9.1.

**Fig. 9.1** A schematic of a typical radial artery line is illustrated here, with the underlying radial artery anatomy overlaid on the hand, showing associated collateral vasculature.

9.2 Anatomy/Physiology

The radial artery is most commonly accessed, followed by the femoral artery, predominantly because of its superficial anatomy and well-established low risk of complications. ¹ Specifically, the radial artery is directly palpable on the skin, supplies the hand with collateral circulation, and, if compromised, does not typically lead to life-threatening complications. Other arteries, such as the femoral, dorsalis pedis, and brachial arteries may be cannulated, but present unique complications such as positional measurements, short life-span, or limb-threatening arterial thromboses. The axillary artery can usually be cannulated safely; however, ultrasound guidance is required.

9.3 Indications

Arterial lines are most frequently performed for continuous, real-time measurement of intra-arterial blood pressure and for providing reliable arterial access for frequent blood sampling.

9.3.1 Measurement of Intra-arterial Blood Pressure

Accurate measurement of blood pressure is vital in all neurocritical care patients. Continuous blood pressure measurement is a crucial component of the resuscitation of a patient in shock. Common scenarios of shock management in the Neuro-ICU would include hypovolemic shock due to severe blood loss, cardiogenic shock due to neurogenic stunned myocardium, neurogenic shock due to spinal cord injury, and septic shock. Conversely, monitoring and treatment of dangerously high blood pressure is equally important. In the Neuro-ICU, maintenance of normal blood pressure is vital to prevent further hemorrhage in a patient with a stroke, intracranial hemorrhage, or recent surgery.

9.3.2 Arterial Access for Frequent Blood Sampling

Frequent blood draws are often required in the ICU setting for both routine, daily laboratory studies, and for evaluating a patient’s respiratory status through arterial blood gases (ABGs). However, in the Neuro-ICU, the arterial line is especially important for more frequent evaluation of laboratory parameters, such as the serum sodium (Na) (i.e., for patients with diabetes insipidus) or the serum osmolality (osm) (i.e., for patients with intracranial hypertension). Through an arterial line, one can avoid repeated puncture of an artery, which can lead to permanent damage, vasospasm, or even limbthreatening thrombosis.

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