Unit 9, Oxygen Analyzers

1. Oxygen concentra= tion should be analyzed because oxygen is a drug and has toxic effects at high percentages. Oxygen therapy is easier to manage if we know exactly how much oxygen is being delivered.

2. = Three primary types of oxygen analyzers:

&= nbsp; &nbs= p; 1. paramagnetic 2. electrical 3. elect= rochemical

3. Paramagnetic analyzer: Pauling’s principle of paramagnetivity= , oxygen is attracted to a magnetic field, oxygen displaces nitrogen causing rotation of the nitrogen-filled dumbbell, degree of rotation is related to = PO₂, light reflects reading on scale.

4. = Paramagnetic analyzer needs a dry sample.

5. = Wet silica crystal-- pink

&= nbsp; Dry silica crystals—blue

6. Paramagnetic analyzer measures partial pressure of oxygen, measures oxygen partial press= ure in all mixtures, needs to be calibrated with change in barometric pressure,= no external power source, doesn’t consume O₂, only provides intermittent reading.

7. Electrical analy= zer: thermal conductivity of oxygen, uses a Wheatstone bridge; based on oxygen’s ability to cool a an electrical w= ire more than air; cooler the wire—the less resistance to electron flow a= nd the greater the current flowing through the wire; i.e. the higher the oxygen percentage—the more electron flow and more voltage.=

8. = Electrical analyzer needs a moist sample to prevent static electricity buildup.

9. Electrical analy= zer actually measures oxygen percentage, does not change with changes in barome= tric pressure; only good for air/oxygen mixtures, only good for intermittent measurements, can’t use with flammable anesthetics.=

10. Subty= pes of electrochemical analyzers: galvanic fuel cell and polarographic<= /span>

11. Electrochemical analyzers: consist of two electrodes (anode and cathode) bathed in an electrolyte solution; oxygen enters solution; chemical reaction takes place; loss of electrons from anode to cathode; voltmeter measures electron flow and conve= rts to oxygen percentage reading.

12. Polar= ographic analyzers generally use a battery to get a quicker response time.

&= nbsp;

&= nbsp; Advantages: quick response time, can be used continuously

Disadvantages: actually measure PO₂n= ot O₂ %, needs to be recalibrated with changes in pressure, moisture on probe will affect reading

13. Elect= rochemical oxygen analyzers are most common type seen in clinical practice.=

14. Oxygen analyzer should be calibrated to 0.21 when FiO₂ is 0.21-0.59; can do this by exposi= ng analyzer to room air. Analyzer should be calibrated to 1.00 when monitored FiO₂ is 0.60-1.00. This can be done by filling glove = with 100% oxygen and inserting analyzer probe into glove.

15. Placi= ng oxygen analyzer:

&= nbsp; &nbs= p; in ventilator circuit- on inspiratory side before humidifier.

&= nbsp; &nbs= p; In head box or oxygen tent- close to child’s face inside device.

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