Arterial oxygenation

Question 1

For estimating lung function Pulmonary function tests in animals are… (3)

Answer 1

not easily available small animals.

▪ Whole body plethysmography in some
university clinics.

Measurement of oxygenation are used instead
▪ Pulse oximetry
▪ Arterial blood gas analysis

Question 2

portion of O2 reversibly bound
to hemoglobin in red blood cells?

how to measure?

Answer 2

98-99% of O2

Measured by pulse oximetry

Question 3

portion of O2 dissolved in plasma?

how to measure?

Answer 3

1-2% of O2 dissolved in plasma

Measured by arterial blood gas
analysis

Question 4

What does pulse oximetry measure exactly?

Answer 4

▪Measures 02 saturation
= percentage of hemoglobin binding sites that are carrying 02

▪ Given as SpO2 %

▪Indirect measurement, but easy, continuous, widely available

▪Sensor attached to tongue, lip, ear, vulva,
preputium

Question 5

What does arterial blood gas analysis measure exactly?

Answer 5

▪Measures the pressure of dissolved 02
in plasma

▪Very accurate values but requires specific
equipment

▪Needle puncture from metatarsal or
femoral artery

Question 6

SpO2 in room air
anesthesia
mild to moderate hypoxemia
severe hypoxemia

Answer 6

SpO2 in room air 98%,
anesthesia 100%,
mild to moderate hypoxemia 91-94%,
severe hypoxemia < 90%

Question 7

Erroneous values in pulse oximetry due to: (6)

Answer 7

Erroneous values due to severe anemia,

hypothermia,
hypoperfusion,

patient movement,
pigmented skin,

excessive ambient light.

Question 8

PaO2 (partial pressure of O2 in arterial blood)
▪ Normal
hypoxemia
severe hypoxemia

Answer 8

Normal > 90 mmHg,
hypoxemia PaO2 < 80 mmHg,
severe hypoxemia PaO2 < 60 mmHg

Question 9

PaCO2 (partial pressure of CO2 in arterial blood) can be used to evaluate?

Normal =

Answer 9

▪PaCO2 (partial pressure of CO2
in arterial blood) To evaluate ventilation

▪ Normal 35-40 mmHg,

too low = hypocapnia,
too high = hypercapnia

Question 10

If a dog’s SpO2 is 80%, estimate what is the corresponding PaO2?

Answer 10

47 mmHg

Question 11

P(A-a)O2 stands for…?

What is it?

What is a normal value?

Answer 11

alveolar arterial oxygen gradient

Difference between alveolar oxygen pressure and arterial oxygen pressure.

Normal < 15-20 mmHg, increased values
indicate pulmonary disease.

Question 12

Answer 12

No

Question 13

Answer 13

60 mmHg

Question 14

Answer 14

Try with another pulse oximeter and check the blood gases.

Question 15

whats happening in this

Answer 15

hypoxemia, hypercapnia and an increased A-a gradient

Question 16

Answer 16

both, hypoventilation and aspiration pneumonia.

Question 17

what is normal P(A-a)O2

Answer 17

< 15-20 mmHg, increased values
indicate pulmonary disease.