Chapter 19. Jugular Venous Oximetry

Introduction

Jugular venous oximetry is a method of analyzing the balance between oxygen supply and demand to the brain. The oxygen saturation of blood draining from the brain into the jugular bulb is continuously measured providing an indirect measure of oxygen extraction by the brain.

Definitions and Terms

• ▪  Jugular venous bulb: Dilation of the internal jugular vein in the jugular fossa of the temporal bone
• ▪  SjvO2: Jugular venous oxygen saturation
• ▪  AVjDO2: Arteriovenous jugular oxygen content (Hgb × 1.34[SaO2 − SjO2] + 0.003[Pao2 − PvO2])
• ▪  CaO2: Arterial oxygen content saturation
• ▪  CjvO2: Jugular venous oxygen saturation
• ▪  CeO2: Cerebral extraction of oxygen (SaO2 [%] − SjvO2 [%])
• ▪  CMRO2: Cerebral metabolic rate of oxygen
• ▪  O2ER: Global cerebral oxygen extraction ratio
• ▪  CMRL: Cerebral metabolic rate of lactate
• ▪  AVDL: Arteriovenous difference of lactate
• ▪  LOI: Lactate Index (AVDL/AVDO2 [ischemia > 0.08])

Techniques

• ▪  Patient consent should be obtained prior to performance of the procedure and the site should be prepped and draped as described in Section 1 (Figure 19-1).
• ▪  The jugular vein is cannulated in the usual fashion, and the SjvO2 catheter is threaded retrograde until it reaches the roof of the jugular bulb, at which point some resistance will be felt (usually 13-15 cm from the skin).
• ▪  The catheter should then be withdrawn approximately 1 cm and monitoring initiated.
• ▪  A skull x-ray is performed after insertion to verify correct position of the catheter tip.
• ▪  Normal SjvO2 is between 55% to 70%.
• ▪  Normal AVjDO2 is 3.5 to 8 mL/dL.
• ▪  Normal CeO2 is 24% to 42%.
• ▪  SjvO2
  • —Greater than 75% implies “luxury perfusion”
  • —Less than 50% represents hypoperfusion
  • —Less than 40% represents ischemia

Clinical Pearls and Pitfalls

• ▪  The signal quality indicator is a measure of the quality of the signal received at the tip of the catheter; poor signal quality may indicate clotting at the tip or that the tip is up against the vessel wall—the catheter should be flushed and/or the head repositioned.
• ▪  Normal SjvO2 are possible even in the face of significant brain pathology:
  • —Focal ischemia may not be apparent.
  • —Venous drainage may be asymmetric.
  • —Infratentorial (brainstem, cerebellum) injuries are not monitored by jugular venous drainage.
• ▪  Jugular venous monitoring is contraindicated in coagulopathy, impaired venous drainage, neck trauma, tracheostomy (risk of infection), cervical spine injuries (difficulty of cannulation), and local infection.

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