Blood Gas Analysis

Question 1

What are the buffering systems of the body?

Answer 1

Chemical (bicarb or proteins/phosphate)
Respiration
Renal

Question 2

What is the Henderson-hasselbalch equation?

Answer 2

PH = pK + log (HCO3-)/(0.03xPaCO2)

Question 3

What variables are measured in a blood gas analysis?

Answer 3

pH
PaCO2
PaO2

Question 4

What variables are cacluated in a arterial blood gas?

Answer 4

HCO3-
BE
Oxygen content

Question 5

T/F: there is no time for metabolic compensation during anesthetia

Answer 5

True

Question 6

__________ is a physiological process, that occurring alone causes and acidemia

Answer 6

Acidosis

Question 7

__________ is a physiological process, that occurring alone causes and alkalemia

Answer 7

Alkalosis

Question 8

Respiratory alkalosis is caused by _________ PaCO2

Answer 8

Decreased

Question 9

Respiratory acidosis is caused by _________ PaCO2

Answer 9

Increased

Question 10

If you have a normal pH with abnormal HCO3- and PaCO2 what would you sususpec?

Answer 10

Mixed acid-base disorder

Question 11

Normal pH is ?

Answer 11

7.35-7.45

Question 12

You have acidemia is ph is ?

Answer 12

PH < 7.35

Question 13

You have alkalemia is pH is ?

Answer 13

PH > 7.45

Question 14

PaCO2 defines _______________

Answer 14

Alveolar ventilation

PaCO2 = CO2 production / alveolar ventilation

Question 15

If PaCO > 45mmHg,

What is the condition in the blood?
State of ventilation?
Acid base disorder?

Answer 15

Hypercapnia
Hypoventilation
Respiratory acidosis

Question 16

If PaCO = 40mmHg,

What is the condition in the blood?
State of ventilation?
Acid base disorder?

Answer 16

Eucapnia
Normal ventilation

None

Question 17

If PaCO < 35mmHg,

What is the condition in the blood?
State of ventilation?
Acid base disorder?

Answer 17

Hypocapnia
Hyperventilation
Respiratory alkalosis

Question 18

What are consequences of hypoventialion?

Answer 18

Lower pH

Hypoxemia if breathing air

Question 19

What is normal HCO3- levels?

Answer 19

24 +/- 4 mEq/L

Cats tend to be lower (22)
Sheep tend to be higher (30)

Question 20

Base excess, defines the ???

Answer 20

Metabolic component of acid-base disturbances

Question 21

Positive BE means?

Answer 21

Metabolic alkalosis

Question 22

Negative BE means?

Answer 22

Metabolic acidosis

Question 23

What is normal BE?

Answer 23

0 +/- 4 mEq/L

Question 24

T/F: TCO2 is almost the same as HCO3-

Answer 24

True

CO2 exists in blood and HCO3-

Question 25

What are the 5 causes of hypoxemia?

Answer 25

Low FiO2
Hypoventilation

Diffusion impairment
V/Q mismatch
Right to left shunt

Question 26

At 100% O2, inspired O2 pressure should be?

Answer 26

(FiO2 x Pambient)

760mmHg

Question 27

At air, inspired O2 pressure should be?

Answer 27

160mmHg

FiO2 x Pambient
0.21. X 76

Question 28

If you are breathing 100% O2, what PaO2 is normal?

Answer 28

500mmHg

Question 29

An animal is hypoxemic at what O2 saturation and pressure?

Answer 29

Sat O2 - 90%

PO2 - 60mmHg

Question 30

What is a normal PaO2/FiO2 ratio?

Answer 30

> 500mmHg

Eg
Air: 110mmHg/0.21 = 523
100% O2: 550mmHg/1 = 550

Question 31

What is the number 1 cause for hypoxia under anesthesia ?

Answer 31

V/Q mismatch

Question 32

What are reasons for V/Q mismatch?

Answer 32

Atelectasis - collapsed lung fields

Lung disease 
-asthma 
-pulmonary edema 
-adult respiratory distress syndrome (ARDS) 
Pneumonia

Question 33

What are the 3 causes of hypoxia?

Answer 33

Hypoxemia
Insufficient perfusion
Insufficient O2 uptake at cellular level

Question 34

What are normal levels of lactate?

Answer 34

1-2mmol/L at rest

Question 35

In a clinical situation, if lactate is > 2mmol/L, it indicates an increased ??

Answer 35

Anaerobic metabolism

Question 36

Abnormally high lactate is commonly caused by??

Answer 36

Tissue perfusion problems

• systemic: shock
• local: tourniquet, intestinal torsion, impaired perfusion of the dependent muscles under anesthesia

Question 37

T/F: high lactate level that does not decrease after treatment indicates poor prognosis

Answer 37

True