Jugular Bulb Oxygen Monitor

7 Jugular Bulb Oxygen Monitor

Amanda Carpenter and Brent Lewis

Abstract

Early identification of dysfunctional oxygenation can prevent secondary brain injury. Jugular venous oximetry provides an indirect idea of oxygen use by the brain–it is used to determine the global balance of cerebral oxygen delivery and consumption. To obtain these measurements, a central venous catheter is inserted into the jugular bulb and a continuous jugular venous oxygen saturation (SjO₂) is recorded. The monitor is inserted via a seldinger technique to reach the jugular bulb. Ideal placement of the catheter is at the lower border of C1, and placement can be confirmed on x-ray.

Keywords: traumatic brain injury, jugular bulb, subarachnoid hemorrhage, neurocritical care, jugular venous oximetry

7.1 Introduction

Mitigation of secondary injury in the brain after a neurologic insult is one of the primary goals of neurocritical care. Dysfunctional oxygenation of brain tissue is an important cause of such secondary injury.

Cerebral oximetry encompasses a range of monitoring modalities to assess (directly or indirectly) the oxygenation status of the brain. These modalities include direct brain tissue oxygen (PbtO₂) monitoring (discussed in Chapter 6), microdialysis monitoring of extracellular glutamate and other molecules, nearinfrared spectroscopy (NIRS) measurement of regional brain tissue oxygen saturation, and jugular bulb oxygen saturation (SjO₂) monitoring.

Here, we discuss the technique for insertion of an SjO₂ monitor. Of the aforementioned cerebral oximetry modalities, only SjO₂ monitoring is recommended by current professional guidelines.¹

Jugular venous oximetry provides an indirect assessment of oxygen use by the brain—it is used to determine the global balance of cerebral oxygen delivery and consumption.

Jugular venous oximetry can be performed intermittently or continuously. Intermittent SjO₂ monitoring entails the insertion of retrograde jugular catheter with subsequent periodic aspiration and laboratory analysis of blood samples from the jugular bulb. Here, we describe the technique for continuous SjO₂ monitoring which is accomplished by insertion of a fiber-optic catheter with an SjO₂ monitor situated within the jugular bulb. For this latter technique, aspiration and laboratory analysis of blood is only required for calibration.

Jugular venous oximetry is a relatively noninvasive, cost-effective, and reliable tool in the armamentarium of critical care physicians.

7.2 Relevant Anatomy and Physiology

Blood from the brain drains mainly through the sigmoid and inferior petrosal sinuses into the internal jugular veins, as seen in ▶ Fig. 7.1. The jugular bulb is the connection between these sinuses and the internal jugular vein, and drains about 70% of the blood from the ipsilateral hemisphere, and 30% from the contralateral hemisphere. To monitor SjO₂, the tip of the fiber-optic catheter is placed into the jugular bulb, conventionally on the side with dominant drainage. Dominance can be determined radiographically by measuring the jugular foramina on computed tomography (CT) scan or functionally, if an intracranial pressure (ICP) monitor is present, by alternatingly compressing both jugular veins and observing the extent of increase in ICP. The right jugular venous pathway is dominant 80% of the time.