Measurement of PaCO2

Question 1

What is PaCO2 a measure of?

Answer 1

Effective alveolar minute ventilation

Question 2

Normal PaCO2

Answer 2

35-45mm Hg
o May be higher in anesthetized SA, considerably higher in anesthetized horses, cattle

Question 3

How Measure with ABG or AVG

Answer 3

Hydrogen ion-sensitive, silver – silver chloride measuring half-cell and reference half-cell

O2 diffuses from test solution in proportion to its partial pressure across semi permeable silicone membrane
o Severinghause electrode
o CO2+ H2O, increases [H+] via carbonic acid equilibration

Hydrogen ion causes electrical potential difference btw half cells that is proportional to change in hydrogen ion concentration –> proportional to change in PCO2

Question 4

PaCO2 >60mm Hg

Answer 4

excessive resp acidosis, sufficient hypoventilation to warrant PPV

Question 5

PaCO2 <20mm Hg

Answer 5

resp alkalosis, decreased CBF (decreased DO2 to brain)

Question 6

Increased PaCO2:PvO2 gradient?

Answer 6

Decreased Tissue Perfusion

Question 7

Normal difference btw PvO2 and PaCO2?

Answer 7

usually 3-6mm Hg higher

Question 8

Hyperventilation

Answer 8

Light ax plane
Hypoxemia
Hyperthermia
Inappropriate ventilator settings
Early pulmonary parenchymal dz

Excitement stage of recovery
delirium
pain
distended bladder
sepsis

Question 9

Hypoventilation

Answer 9

Excessive ax depth
NM disease
Airway obstruction
Pleural space disease
Late pulmonary parenchymal dz
Inappropriate ventilator settings
Malfunctioning AM - exhausted absorbent, stuck unidirectional valves, low FGF with NRB