ABGs Flashcards
Normal values for HCO3
22-28 mmol
Normal values for pH
7.35-7.45
Normal values for PaCO2
35-45mmHg
Normal values for PaO2
80-100mmHg
Normal values for BE
-3 to 3
Normal values for SaO2
95-100%
Lactic acid is a…
By product of metabolism (ATP-PC system)
Causes of respiratory acidosis
Hypoventilation aka ineffective ventilation - acute (imbalance between respiratory muscle strength and load) or chronic (COPD)
Causes of respiratory alkalosis
Hyperventilation - shock, lung causes, pneumonia, oedema, PE, meningitis, intracerebral haemorrhage, fever, hyperthyroidism, pain, anxiety
Causes of metabolic acidosis
Overwhelming acid load or kidney problems - ingestion of exogenous acid, lactic acidosis type A or B, ketoacidosis, inability to excrete acid from renal failure, loss of bicarb (diarrhoea or ileostomy), renal problems (loss of bicarb)
Causes of metabolic alkalosis
Overwhelming base load or dehydration - diuretic use, vomiting (loss of HCI)
The P/F ratio indicates
V/Q matching
PaCO2 determines
Minute ventilation problem (also the V inn V/Q)
Ann increase in PaCO2 of 20mmHg causes pH to decrease by
0.1
PaCO2 of 60mmHg, the pH will be
7.3
PaCO2 of 80, the pH will be
7.2
Lactic acidosis is
Lactate + H2O
Keto-acidosis is
Ketones + H2O
Normal P/F ratio value
400+
P/F ratio of 80mmHg on 21% O2
380
P/F ratio of 80mmHHg on 50% O2
160
Type 1 resp failure is
1 problem (V/Q): low P/F ratio <300-400
Type 2 resp failure is
2 problems (hypoventilation and V/Q): elevated PaCO2 and low P/F ratio <300
