Acid-base Flashcards
What is the pH of our bodies?
6.8-7.8
preferred =7.4
How is the pH adjusted in our bodies?
- Chemical buffering
- Principle buffer system: H2CO3/HCO3-
- Breathing
- PCO2 (dissolved CO2 gas in blood)
- Kidneys
- Reabsorption of HCO3-
- Excretion of H+
Tests to assess blood pH? Which blood is tested (venous/arterial?)
pH, arterial blood Po2, arterial blood Pco2, arterial blood Bicarbonate (HCO3), Base excess, arterial blood Anion Gap, venous blood Bicarbonate (HCO3), venous blood
What is Po2 a maker of?
level of blood oxygenation
What is PCO2 a marker of?
Lungs ability to excrete CO2
What are the diagnosis steps to assess respiratory/metabolic acidosis/alkalosis
- Assess pH of blood
- Assess PCO2
- Assess blood HCO3-
- Assess anion gap
- Assess compensation
mnemonic to differentiate respiratory respiratory/metabolic acidosis/alkalosis
ROME
Respiratory Opposite:
↑pH ↓PCO2-> alkalosis
↓ pH ↑PCO2-> Acidosis
Metabolic equal
↑pH ↑PCO2-> alkalosis
↓ pH ↓PCO2-> Acidosis
What are the consequences of gastric removal in terms of acid-base balance
tube is suctioning gastric contents-> patient may lose a lot of acid
if they have acid depletion-> increased ph-> alkalosis
Causes of metabolic acidosis
- GI loss of HCO3-
- Diarrhea
- Pancreatic or SB fistula
- Ketoacidosis
- PN containing chloride salts
Causes of metabolic alkalosis
- Emesis (vomiting)
- Nasogastric suction
- Diuretic therapy
- Excessive bicarb administration
Metabolic acidosis
What is the status of pH and HCO3?
What is the treatment?
↓pH
normal or ↓PCO2
Treatment: PN, add acetate
Metabolic alkalosis
What is the status of pH and HCO3?
What is the treatment?
↑pH ↑PCO2-> alkalosis
Treatment: PN, decrease acetate
what should be PN content be in terms of acetate and chloride if there is no acid-base disorder?
no AB disorder-> just enough acetate to balance chloride -> 1:1 ratio of acetate:chloride
what is anion gap?
the difference between unmeasured anions and cations;
Definition of Respiratory Acidosis
Respiratory acidosis occurs when there is an excess of acid in relationship to base caused by retention of carbon dioxide. This generally occurs when there is an inability of the lungs to expire CO2.
