Blood Gas Analysis Flashcards
Which drugs have minimal CV effects?
Etomidate
Alfaxalone
Midazolam
Hydromorphone
Normal pH
7.35-7.45
Primary acid base disorder
defined by the initial change in HCO3 or PaCO2
Compensation
secondary change in HCO3 or PaCO2 in order to attenuate the effect of the primary disorder on blood pH.
Base Excess
to an excess or deficit in the amount of base present in the blood
Positive Base Excess
metabolic alkalosis
Negative Base Excess
metabolic acidosis
PaCO2
alveolar ventilation
Increased PaCO2 will…
Lower the PaO2
Lower the pH
Reflect respiratory acidosis
Reflect Respiratory compensation
FiO2
Inspired O2 fraction
PiO2
inspired O2 pressure
V/Q mismatch
Lower than expected PaO2 values may indicate inadequate gas exchange resulting in pulmonary atelectasis
A-a difference
PaO2 is always lower than PAO2
Causes for high A-a difference
V/Q mismatch
Right to left shunt
Diffusion impairment
Reasons for V/Q Mismatch
Atelectasis
Lung diseases
A-a difference
used to distinguish lung diseases from hypoventilation as a cause of hypoxemia
5 causes of hypoxemia
Low FiO2 Hypoventilation Diffusion impairment V/Q mismatch Right to left shunt
Hypoxia
insufficient oxygenation of the tissues
Caused of Hypoxia
Hypoxemia
Insufficient tissue perfusion
insufficient O2 uptake
What is PaO2 is mostly defined by?
Concentration of Hemoglobin
SaO2
What is considered high for lactate?
> 2mmol/L
Indicates increased anaerobic metabolism
Lactic acidosis
Tissue hypoxia leads to increased anaerobic metabolism and produces lactate and acids
Low PaO2 /FiO2 ratio
V/Q mismatch caused by atelectasis due to anesthesia
