Wk 2 ABGs Flashcards
Why do we use ABGs?
Gives us the best representation of the pH and CO2
What is the purpose of ABGs?
to ASSESS acid/base status and to determine adequacy of oxygenation and ventilation
Normal PaCO2 range
35-45 mmHg
pH is essentially the balance of…
hydrogen ions
PaCO2 is a __ parameter
respiratory (H20 + CO2 = carbonic acid)
HCO3 is a __ parameter
metabolic
Normal HCO3 range on ABG
22-26 mEq/L
HCO3- is a __ value on the ABG
calculated
What is HCO3- reported as on the venous chemistry panel?
CO2
What is a primary event for acid/base balance?
The problem that initiates the acid/base balance
4 examples of primary even for acid/base balance
Hyperventilation
Hypoventilation
Vomiting
Diarrhea
What is the primary disorder?
The result of the primary event
Two examples of a primary disorder?
Respiratory acidosis
Metabolic alkalosis
If there is a problem with the kidneys, the lungs will compensate. What is the problem with this?
The lungs cannot compensate for a long period of time like the kidneys can
What would we do for a patient with renal failure?
Dialysis and/or bicarb
Metabolic imbalances are related to…
Bicarbonate (HCO3-)
Kidneys
Respiratory imbalances are related to…
H2CO3 (carbonic acid)
Increase or decrease in CO2, changes in ventilation
respiratory alkalosis or acidosis
Changes in [H+] or bicarbonate ions
metabolic alkalosis or acidosis
Acid base pneumonic ROME
R- Respiratory
O- Opposite
M- Metabolic
E- Equal
If pH is up and PCO2 is down then it is…
respiratory alkalosis
If pH is down and PCO2 is up then it is…
respiratory acidosis
If pH is up and HCO3 is up then it is…
metabolic alkalosis
If pH is down and HCO3 is down then it is…
metabolic acidosis
What is HCO3?
bicarbonate
What is metabolic alkalosis?
Too much bicarbonate or not enough carbonic acid
What are the ABGs of someone with metabolic alkalosis?
pH: >7.48
PaCO2: 35-45 (lungs not compensating yet)
HCO3: >26
What are dietary causes metabolic alkalosis
Taking in excess baking soda or alia-seltzer (too much base)
What happens if you take in too much base?
Hydrogen shift outside the cell causing potassium to go into cell (hypokalemia)
3 other causes of metabolic alkalosis?
Prolonged vomiting (losing HCl from stomach) NG tube (pulling out HCl from stomach) Diuretics (loop)
What are neurologic symptoms of metabolic alkalosis?
CNS over-excitability, muscle tremors, cramps, confusion, parathesias, coma,
What are two other symptoms of metabolic alkalosis?
Respiratory depression
N/V/D
Hypokalemia
In respiratory alkalosis, there is a __ __ deficit
carbonic acid (H2CO3)
What are the ABG levels of someone with respiratory alkalosis?
pH >7.45
PaCO2 <35
HCO3 22-26 (kidneys not begun to compensate yet)
What causes respiratory alkalosis?
Anything that can cause an increase in breathing
What are the symptoms of respiratory alkalosis?
CNS over-excitability
Tachypnea, confusion, light headedness, parathesia, hyperactive reflexes, coma, hypotension
What causes respiratory acidosis?
Excess carbonic acid, hypoventilation
Acute versus chronic respiratory acidosis
respiratory arrest versus COPD
ABGs of someone with respiratory acidosis
pH <7.35
PaCO2 >45
HCO3 22-26 (kidneys react slow with acute)
In a patient with COPD and respiratory acidosis, their pH will…
Return to normal once the kidneys have had time to compensate. HCO3 will be high.
What are the symptoms of respiratory acidosis?
CNS depression including hypoventilation
Headache, restlessness, confusion
tachycardia, LOC, coma
3 causes of respiratory acidosis
Cardiopulmonary arrest Head injury Narcotics Anesthesia Pulmonary disorders Uncontrolled pain (hurts to breath) Abdominal distention Airway obstruction Chest wall deformities
What is metabolic acidosis?
Excess acids or loss of bicarb (base)
ABGs of metabolic acidosis
pH <7.35
PaCO2 35-45
HCO3 <22
Common causes of metabolic acidosis
Renal disease fistulas diabetes lactic acidosis prolonged diarrhea starvation shock cardiac arrest
What type of diabetes is associated with metabolic acidosis?
Type 1 - DKA
How does prolonged diarrhea cause metabolic acidosis?
Relative increased acid due to loss of HCO3
How does starvation cause metabolic acidosis?
Using fat for energy causing ketosis
Metabolic acidosis causes an increase in what type of acid and why?
Lactic acid due to lack of oxygen to the tissues
What are the s/s of metabolic acidosis?
CNS over-excitability
Confusion, lethargy, tremors, parathesias
hypotension, hyperkalemia
Kussmal respirations
