Acid Base Flashcards
What is acidemia
when blood has elevated H+
What is alkalemia
When blood has decreased H+
What is respiratory acidosis?
when hypoventilation causes hypercapnia
What is respiratory alkalosis?
when hyperventilation causes hypocapnia
What is metabolic acidosis?
when an acid is produced or a base is lost
What is metabolic alkalosis?
when a base is added or an acid is lost
What kind of acids/bases are counteracted by the bicarb buffer system?
metabolic acids or bases
requires ventilation and gas exchange to allow for CO2 excretion
What are extracellular examples of nonbicarb buffers?
plasma proteins, phosphate and ammonia
What are intracellular examples of nonbicarb buffers?
dibasic phosphate, proteins, and bone bicarb
Define the isohydric principle
the acid/base ratio of a buffer is determined by it’s Ka and [H+]
i.e. a change in [H+} changes ALL acid/base ratios in all buffers
What is the henderson hasselbach equation
pH = Pk + log (bicarb/0.03xPCO2)
What is the first defense to changes in pH
physical and chemical buffers
What is the second defense to changes in pH over a scale of minutes?
respiratory compensation
What is the long term solution to changes in pH?
renal excretion and or metabolism
An immediate and pronounced drop in bicarbonate and a transient increase in PaCO2 would indicate what process?
uncomplicated metabolic acidosis
A pronounced increase in bicarb with a transient increase in PaCO2 would indicate what process?
uncomplicated metabolic alkalosis
What are respiratory processes buffered by?
non bicarbonate buffers only!
the change in bicarb concentration is always equal to the change in what value?
the H+ taken or added to the system
With increasing hemoglobin concentration, what happens to the buffer value?
it increases
What is the natural response to metabolic acidosis?
respiratory alkalosis via increase in ventilation, dropping concentration of both bicarb and non bicarb buffers
What is the natural compensation for metabolic alkalosis?
respiratory acidosis
The rapid intravenous infusion of bicarbonate into a 70 kg male initially increased arterial pH from 7.40 to 7.51 and [bicarb] from 24 to 32 mEq/L. However, over the next 3 hr the arterial [bicarb] decreased to 27 mEq/L and pH decreased to 7.45. What caused the fall in bicarbonate and pH over the 3 hr period?
equilibration of bicarbonate will cause an increase in pH that has a tendency to decrease breathing by increasing arterial PCO2, which in turn will increase brain PCO2, dropping brain pH and causing respiratory stimulation. This will drop PCO2 and pull the reaction away from production of bicarbonate by expiring CO2
The rapid intravenous infusion of bicarbonate into a 70 kg male initially increased arterial pH from 7.40 to 7.51 and [bicarb] from 24 to 32 mEq/L. However, over the next 3 hr the arterial [bicarb] decreased to 27 mEq/L and pH decreased to 7.45. How will acid-base balanced be restored?
excretion of bicarbonate in the urine
If a patient’s PaCo2 is consistently at 40 mmHg, what factors determine how much extracellular pH changes in response to an increase in acid load?
The concentration of extracellular and intracellular buffers will determine the magnitude of the change in extracellular pH.
Long term, there may be compensation in excretion by the kidneys.
A patient has a low pHa, low bicarb, and low PaCo2. Are they in respiratory or metabolic acidosis?
metabolic acidosis (both pH and CO2 are low)
