Chapter 157 Emerging Monitoring Techniques

Question 1

What are the three main determinants of venous hemoglobin oxygen saturation (SvO2)?

Answer 1

1. Cardiac output
2. Hemoglobin concentration
3. Arterial oxygen concentration (CaO2)

Question 2

What value is recommended as a resuscitation endpoint for SvO2?

Answer 2

> 70% when measuring central venous values (via jugular venipuncture or indwelling jug catheter - NOT peripheral blood)

Question 3

What does an SvO2 <65% indicate?

Answer 3

<65% indicates increased oxygen extraction due to decreased oxygen supply (inadequate cardiac output, anemia, hypoxemia or even rise in oxygen demand)

Question 4

What does an SvO2 >75 might suggest?

Answer 4

May suggest an underlying defect in oxygen extraction, as can occur with mitochondrial dysfunction with sepsis or cytotoxic tissue hypoxia.

Question 5

What are some parameters used to evaluate hemodynamic instability despite absence of hypotension?

Answer 5

Peripheral temperature, SPO2, CRT and mucous membrane color

Question 6

What is the benefit of performing temperature gradient monitoring?

Answer 6

One may be able to detect hypoperfusion prior to heart rate, rectal temperature, systemic BP

Question 7

What is the concept of sublingual capnometry based on?

Answer 7

The knowledge that when there is loclal hypoperfusion and ischemia, there is a local increase in the production of H+ ions and lactate and an accumulation of CO2.

Question 8

How can one use pulse oximetry to evaluate systolic blood pressure?

Answer 8

Compress the cuff with a sphygmomanometer until the plethysmographic curve disappears. Then when the cuff is deflated slowly, the first curve to appear is the systolic blood pressure.