Mixed Venous Oxygen Saturation (SvO2)

Question 1

ScVO2

Answer 1

Mixed gas from the superior vena cava

Question 2

SvO2

Answer 2

• Mixed gas from the pulmonary artery
• A calculation btwn arterial oxygen supply & oxygen demand of body

Question 3

SvO2 Determined by

Answer 3

• Oxygen extraction and oxygen consumption by the tissues
  > the amnt of O2 remaining after tissue extraction
  > sampled obtained from the pulm artery

Question 4

Factors tht Make up SvO2 are

Answer 4

• Cardiac output
• Hemoglobin
• SaO2
  > arterial oxygen saturation
• VO2
  > oxygen consumption
• Normal Values: 60-80%

Question 5

SvO2 - Indications

Answer 5

• Critically ill pt who has potential to develop an imbalance btwn oxygen supply & metabolic tissue demand
• Dcrd SvO2 values
  > dcrd oxygen delivery factors:
  > hgb: oxygen transporter
  > cardiac output: not enough circulation
  > oxygen sat
• Incrd oxygen demands
  > anything tht incrs oxygen consumption at cellular lvl

Question 6

Decreased SvO2

Answer 6

• Dcrd O2 delivery
  > dcrd RBCs
  > low hgb concentration: anemia or hemorrhage
• Dcrd oxygen sat (SaO2)
  > hypoxemia, lung disease, low FiO2
• Dcrd cardiac output
  > LC dysfunc: cardiac disease, drugs (beta blocks, illicit)
  > cardiac & late septic shock, hypovolemia, dysrhythmias, low preload
• Incrd oxygen consumption
  > can be controlled better
  > fever, infection, seizures, agitation, shivering, incrd work of breathing, suctioning, bathing, repositioning

Question 7

Increased SvO2

Answer 7

• Sepsis
  > RBC can’t drop off O2 due to obstruction from bacteria
• Wedged PA catheter
  > leaving balloon inflated after getting PAOP reading
  > high risk of infarction