Module 2: End-Organ Perfusion

Question 1

end organ perfusion assessment

Answer 1

• continued imbalance of O2 supply and demand will result in dysfunction of one of the major end organ systems:
  Neuro
  Cardio
  Resp
  GI
  GU
• global markers are assessments that provide info about global cellular oxygenation, and don’t provide cues about a specific organ

Question 2

neurological assessment cues and rationale

Answer 2

Cues: decreased LOC, restlessness, agitation, coma

Rationale: brain doesn’t store O2 or glucose, meaning reduction in delivery of these things is disruptive to normal cellular functioning

Question 3

cardiovascular assessment cues and rationale

Answer 3

Cues: chest pain, ECG changes, biochemical markers

Rationale: decreased O2 delivery to cardiac muscle causes ischemia and pain. Damage to myocardial tissue from prolonged O2 deprivation can lead to electrical conduction problems and dysrhythmias. Injured cardiomyocytes release biomarkers into the bloodstream.

Question 4

respiratory assessment cues and rationale

Answer 4

Cues: PaO2, PaCO2, SaO2

Rationale: decreased O2 availability to lungs and resp muscles will decrease gas exchange and impact levels of PaO2, SaO2 and PaCO2

Question 5

GI (and liver) assessment cues and rationale

Answer 5

Cues: n/v, high residuals, abdo pain, ischemic bowel, LFTs

Rationale: decreased O2 availability to GI tissues results in dysfunction. Digestion and peristalsis slow or stop. Ischemic or damaged hepatic cells release enzymes into the blood.

Question 6

GU assessment cues and rationale

Answer 6

Cues: BUN, eGFR, creatinine, urine output

Rationale: decreased oxygen availability to renal cells results in decrease in function. Filtering and clearance of waste is impacted. This leads to an increase in BUN and creatinine and decrease in GFR and urine output.

Question 7

global assessment cues and rationale

Answer 7

Cues: warmth, colour, cap refill, mottling (skin); mixed venous (SCVO2 and SVO2), lactate (global markers)

Rationale: visual and palpation skin ax’s can give us clues about general tissue perfusion. Lactate and SCVO2 are blood tests that give a global perspective of the body’s O2 supply and demand balance. They do not indicate function or dysfunction in any one organ.

Question 8

what are commonly used as global markers to assess tissue oxygenation?

Answer 8

lactate and mixed venous oxygen saturation

Question 9

what does the global markers provide info about?

Answer 9

the overall state of tissue perfusion, metabolism, and oxygen utilization

Question 10

what can indicate inadequate tissue oxygenation and metabolism?

Answer 10

increased lactate levels and decreased mixed venous oxygen saturation

Question 11

what happens when cellular oxygen supply is inadequate?

Answer 11

the cell will convert its energy production from aerobic metabolism (utilizing oxygen) to anaerobic metabolism (which is not dependent on oxygen)

Question 12

what is the end-product of anaerobic metabolism?

Answer 12

lactic acid

Question 13

is serum lactate organ-specific?

Answer 13

no; provides an overall reflection of end-organ perfusion and the degree to which oxygen supply meets oxygen demand for the whole body

Question 14

what does mixed venous measurement reflect?

Answer 14

the balance between oxygen delivery and oxygen consumption

Question 15

what does a lower than normal mixed venous indicate?

Answer 15

an increase in demand and/or a decrease in supply

Question 16

what does a higher than normal mixed venous indicate?

Answer 16

a decrease in demand and/or an increase in supply

Question 17

how do you measure mixed venous?

Answer 17

1) blood sample taken from a central line terminating just above the right ventricle (SCVO2); most common; captures blood return from the head and UE

2) obtained from the pulmonary artery and measures blood return from the head and arms, the gut and LE, and the coronary veins; true mixed venous; SVO2