oxygenators/reservoirs

Question 1

How is oxygen being transported in the blood?

Answer 1

bound: 210ml/l
solved: 3ml/l

bound transport can only happen after being in the solved state first

Question 2

Partial pressures in arteries/venes?

Answer 2

ven:
pO2: 40
pCO2: 46

art:
pO2: 100
pCO2: 40

Question 3

What is the pO2 in the lung alveoles?

Answer 3

103 mmHg

Question 4

What is the friction index?

Answer 4

the relation of pure O2 and atmospheric air in a gas mixture

Question 5

Describe the general structure of an oxygenator.

Answer 5

oxygenating part with a semi permeable membrane, separating blood and gas from one another.
temperature regulating part with a heat exchanger, allowing for the blood to be cooled down or warmed up by convection

Question 6

What types of oxygenators exist?

Answer 6

screen, bubble, membrane

Question 7

How does the membrane oxygenator work?

Answer 7

there are hollow and flat fibric membranes.
oxygen flows from the inside through the fibers and is being circulated by the blood around the fibers from the outside, letting the gas exchange happen

Question 8

What is a microporous membrane?

Answer 8

during membrane production, oil drops are added and later washed out of, leaving those areas to be porous and reducing the amount of plasma leaking.

Question 9

What is plasma leakage?

Answer 9

breaching of blood plasma due to temperature difference of gas and blood, leading to the creating of foam, which clogs the pores -> reduced oxygenation -> only for short time use (4hrs max). narcotic gases can pass through

Question 10

What are diffusion membranes?

Answer 10

highly permeable for gas, non micro porous, anti thrombolic, conservative for blood, no blood gas contact -> therefore no plasma leakage but less effective gas exchange -> used for long term uses like ECMO (up to 14d).
narcotic gasses cannot pas through them

Question 11

What material are the various membrane types made off?

Answer 11

(microporous) oxygenator membranes are made out off polypropylene, whereas diffusion membranes are made out off polymethlypentene or silicone

Question 12

Are oxygenator membranes hydrophil or hydrophobic?

Answer 12

membrane: hydrophilic
diffusion: hydrophobic

Question 13

Name 5 important parameters for gas exchange.

Answer 13

HKT
pO2
pCO2
blood flow rate
blood temperature

Question 14

Compare the oxygenation process in lung and oxygenator.

Answer 14

surface: 150 -> 1.5 m2
bloodfilm: 6 to 15 -> 200 micron
contact time: 0.1 to 0.75 -> up to 10s
pO2: up to 100 -> 720 mmHg
pCO2: 40 -> 45 mmHg
flow: 5 l/min
volume: 1l -> 200-300 ml
capillary length: 0.1mm -> 2 to 20 cm

Question 15

What is the job of a reservoir?

Answer 15

volume buffer so the differences in arterial and venous flow can be compensated. additionally, the patients blood has to be diluted due to an increased perfusion volume with hlm

Question 16

Pro/contra for open reservoir?

Answer 16

+ priming with self employed de-airing
+ clear case -> good observation
+ exact blood level control
+ biocompatible material

• danger of air embolism
• case can break
• level sensor needed

Question 17

Pro/contra for closed reservoir?

Answer 17

+ no level sensor -> walls like valve
+ self employed de-airing through purge line

• harder to prime
• expansion of bag bc of heat
• non exact level control

Question 18

What additional monitoring for open reservoir required?

Answer 18

In an open reservoir, the air can be pumped out to the patient (air embolism), if the blood level is too low, therefore we should have a level sensor in the lower part of the reservoir. -> ultrasound sensor & detector

Question 19

How can a closed reservoir be constantly ventilated?

Answer 19

purge line -> vacuum line to suck out air of the reservoir

Question 20

Name the function of a cardiotomic reservoir.

Answer 20

the backflow from vent, sucker and cardioplegia pumps get redirected to the cardiotomy reservoir, where they are filtered and defoamed and led back to the venous reservoir for recirculation