Blood Gas Analysis Flashcards
What are the buffering systems of the body?
Chemical (bicarb or proteins/phosphate)
Respiration
Renal
What is the Henderson-hasselbalch equation?
PH = pK + log (HCO3-)/(0.03xPaCO2)
What variables are measured in a blood gas analysis?
pH
PaCO2
PaO2
What variables are cacluated in a arterial blood gas?
HCO3-
BE
Oxygen content
T/F: there is no time for metabolic compensation during anesthetia
True
__________ is a physiological process, that occurring alone causes and acidemia
Acidosis
__________ is a physiological process, that occurring alone causes and alkalemia
Alkalosis
Respiratory alkalosis is caused by _________ PaCO2
Decreased
Respiratory acidosis is caused by _________ PaCO2
Increased
If you have a normal pH with abnormal HCO3- and PaCO2 what would you sususpec?
Mixed acid-base disorder
Normal pH is ?
7.35-7.45
You have acidemia is ph is ?
PH < 7.35
You have alkalemia is pH is ?
PH > 7.45
PaCO2 defines _______________
Alveolar ventilation
PaCO2 = CO2 production / alveolar ventilation
If PaCO > 45mmHg,
What is the condition in the blood?
State of ventilation?
Acid base disorder?
Hypercapnia
Hypoventilation
Respiratory acidosis
If PaCO = 40mmHg,
What is the condition in the blood?
State of ventilation?
Acid base disorder?
Eucapnia
Normal ventilation
None
If PaCO < 35mmHg,
What is the condition in the blood?
State of ventilation?
Acid base disorder?
Hypocapnia
Hyperventilation
Respiratory alkalosis
What are consequences of hypoventialion?
Lower pH
Hypoxemia if breathing air
What is normal HCO3- levels?
24 +/- 4 mEq/L
Cats tend to be lower (22)
Sheep tend to be higher (30)
Base excess, defines the ???
Metabolic component of acid-base disturbances
Positive BE means?
Metabolic alkalosis
Negative BE means?
Metabolic acidosis
What is normal BE?
0 +/- 4 mEq/L
T/F: TCO2 is almost the same as HCO3-
True
CO2 exists in blood and HCO3-
What are the 5 causes of hypoxemia?
Low FiO2
Hypoventilation
Diffusion impairment
V/Q mismatch
Right to left shunt
At 100% O2, inspired O2 pressure should be?
(FiO2 x Pambient)
760mmHg
At air, inspired O2 pressure should be?
160mmHg
FiO2 x Pambient
0.21. X 76
If you are breathing 100% O2, what PaO2 is normal?
500mmHg
An animal is hypoxemic at what O2 saturation and pressure?
Sat O2 - 90%
PO2 - 60mmHg
What is a normal PaO2/FiO2 ratio?
> 500mmHg
Eg
Air: 110mmHg/0.21 = 523
100% O2: 550mmHg/1 = 550
What is the number 1 cause for hypoxia under anesthesia ?
V/Q mismatch
What are reasons for V/Q mismatch?
Atelectasis - collapsed lung fields
Lung disease -asthma -pulmonary edema -adult respiratory distress syndrome (ARDS) Pneumonia
What are the 3 causes of hypoxia?
Hypoxemia
Insufficient perfusion
Insufficient O2 uptake at cellular level
What are normal levels of lactate?
1-2mmol/L at rest
In a clinical situation, if lactate is > 2mmol/L, it indicates an increased ??
Anaerobic metabolism
Abnormally high lactate is commonly caused by??
Tissue perfusion problems
- systemic: shock
- local: tourniquet, intestinal torsion, impaired perfusion of the dependent muscles under anesthesia
T/F: high lactate level that does not decrease after treatment indicates poor prognosis
True
