Clin Path - Blood Gases

Front 1

Acidosis
-define

Back 1

-a condition in which acidemia tends to occur
-blood pH is decreasing because of the condition
-primary or compensatory

Front 2

Alkalosis
-define

Back 2

-a condition in which alkalemia tends to occur
-blood pH is increasing because of the condition
-primary or compensatory

Front 3

Why would an animal not be acidemic or alkalotic even though it has acidosis/alkalosis?

Back 3

-compensatory mechanisms
-wide reference interval

Front 4

Hypercapnia
-define

Back 4

-excess CO2 in the blood
-inc. PaCO2

Front 5

Hypocapnia
-define

Back 5

-deficiency of CO2 in blood
-dec. PaCO2

Front 6

Hypoxemia
-define

Back 6

-deficiency of dissolved oxygen in blood
-dec. PaO2

Front 7

Hypoxia
-define

Back 7

-deficient O2 reaching tissues

Front 8

Major component of air

Back 8

-nitrogen

Front 9

Total atmospheric pressure

Back 9

-760 mmHg

Front 10

PCO2

Back 10

-pressure created by CO2 that is dissolved in plasma

Front 11

PO2

Back 11

-pressure created by O2 that is dissolved in plasma

Front 12

When PO2 and PCO2 of a blood sample are measured, what is not included?

Back 12

-O2 = in RBCs
-CO2 = in RBCs and Protein-bound CO2

Front 13

Hyperventilation
-define
-results in

Back 13

-increased rate or depth of breathing
-results in increased loss of CO2 (can lead to hypocapnia)

Front 14

Hypoventilation
-define
-results in

Back 14

-decreased rate or depth of breathing
-results in decreased loss of CO2 (can lead to hypercapnia)

Front 15

Tachypnea
-define

Back 15

-increased rate of respiration

Front 16

Bradypnea
-define

Back 16

-decreased rate of respiration

Front 17

What is produced when H+ is buffered by HCO3-?

Back 17

-H2O & CO2 produced
-CO2 dissolves and contributes to PCO2

Front 18

H+ buffers

Back 18

-HCO3-
-renal excretion (NH4 & H2PO4)
-Hgb
-Bone
-Plasma Protein

Front 19

How to estimate [H2CO3] (carbonic acid)

Back 19

PCO2 x 0.03

Front 20

Acidemia and Alkalemia represented by the Henderson-Hasselbalch equation

Back 20

-acidemia = dec. in [HCO3-] : PaCO2
-alkalosis = inc. in [HCO3-] : PaCO2

Front 21

What are measured by blood gas instruments?

Back 21

-[H+] (in terms of pH
-PCO2 (partial pressures dissolved in plasma)
-PO2

Front 22

[HCO3-]
-how is it calculated

Back 22

-Henderson-Hasselbalch (pH = 6.1 + log([HCO3-]/(PCO2 x 0.03))

Front 23

[tCO2]
-how is it calculated

Back 23

-[tCO2] = [HCO3-] + (PCO2 x 0.03)
-[tCO2] = [HCO3-]

Front 24

What is [tCO2]?

Back 24

-total CO2 from an anaerobic sample
-CO2 from the sample + CO2 from buffering of H+ by HCO3-

Front 25

Arterial heparinized whole blood is preferred for...

Back 25

-assessment of pulmonary function
-oxygenation of blood

Front 26

Venoud heparinized whole blood is preferred for...

Back 26

-assessment of metabolic disorders

Front 27

Why is venous blood slightly more acidic than arterial blood?

Back 27

-transporting H+ that was produced during cellular metabolism
-transported to the lungs and eventually the kidneys for removal

Front 28

Why can't PCO2 from venous blood be used to assess pulmonary function?

Back 28

-it's not accurate because the source of the blood can provide different PCO2 values

Front 29

Where can mixed venous blood be collected from?

Back 29

-vena cava
-right ventricle

Front 30

PCO2 depends on...

Back 30

-what is happening in the tissue being drained
-what is happening in the lungs

Front 31

How does venous [HCO3-] compare to arterial [HCO3-]?

Back 31

-proportional

Front 32

Plasma [HCO3-] is dependent on?

Back 32

-PCO2
-pH
(Henderson-Hasselbalch)

Front 33

Should blood being assayed for gases be collected with a plastic syringe?

Back 33

-no
-gas can pas through the plastic
-and diffuse even faster if put on ice

Front 34

Why should a green top tube not be used for blood gas analysis?

Back 34

-heparin
-gases will diffuse into the dead space of the tube

Front 35

Erroneous blood gas analytics can be due to:

Back 35

-exposure to air/excess heparin in sample
-delayed sample analysis

Front 36

Only acceptable sample for measuring PaO2

Back 36

-heparinized arterial samples
-PaO2 = amount of O2 dissolved in plasma, not amount bound to hemoglobin

Front 37

Where is most oxygen in blood?

Back 37

-bound to hemoglobin

Front 38

When is SO2 near 100%?

Back 38

-when PaO2 > 90 mmHg

Front 39

Factors that will shift the Oxygen-Hemoglobin dissociation curve to the right

Back 39

-inc. [H+]
-inc. [2,3-DGP]
-inc. temp
-inc. PCO2

Front 40

Hypoxia with hypoxemia
-causes

Back 40

-atmospheric hypoxia (dec. O2 content in air)
-tidal hypoxia (impaired respiratory exchange)
-alveolar hypoxia (decreased alveolar function)

Front 41

Hypoxia without hypoxemia
-causes

Back 41

-hemoglobinemic hypoxia (dec. O2 bound or dec. Hgb or methemeglobinemia)
-stagnant hypoxia (poor blood circulation dec. delivery to tissue)
-histotoxic hypoxia (defective O2 use by tissues because of metabolic pathways)
-demand hypoxia (inc. O2 demand from hyperfunctioning cells)

Front 42

What can be causes of alveolar hypoxia?

Back 42

O2 not diffusing across the alveolus into the capillary due to:
-pneumonia
-exudates

Front 43

Diseases and conditions that cause hypoxemia

Back 43

-dec. inhaled O2 content
-inhibition of medullary respiratory center
-inhibition of respiratory muscles
-upper airway dysfunction (foreign body, vomit, mechanical hypoventilation)
-Impaired gas exchange at the pulmonary capillaries

Front 44

What 2 components are needed for gas exchange?

Back 44

-ventilation
-perfusion

Front 45

Ventilation
-definition

Back 45

-amount of air getting to alveoli

Front 46

Perfusion
-defintion

Back 46

-amount of blood getting to alveoli