Acid base tutorial Flashcards
What is ABG?
ABG= Arterial Blood Gas
How is ABG taken and What ABG info is taken from ABG?
Which part of that info will tell you that there is an ABG problem?
ABG is taken from the radial artery
PH/PCO2/O2/HCO3-/O2 sat is taken from ABG
PH/PCO2/HCO3- are used to determine a blood gas problem
What is the equation for the buffering system in the body?
What represents each side of that equation?
H2O + CO2↔ H2CO3 ↔ H+ + HCO3-
Left Lungs (respiratory) Right Kidneys (metabollic)
What is the shift when there is a build up in H+ or CO2? What gets rid of the other?
H2O + CO2↔ H2CO3 ↔ H+ + HCO3-
H+ increase- shift left lungs responds
CO2 build up shift right kidney respond
What is the HH equation for the buffering system?
How do HCO3 and PCO2 relate to pH?
pH= 6.1 + log [HCO3-]/PCO2 x 0.03
Short form pH=HCO3/PCO2
if HCO3 goes up then pH goes up/if down then pH goes down (direct relationship)
If PCO2 goes up then pH goes down/if PCO2 goes down pH goes up (inverse relationship)
What manages HCO3 and PCO2
HCO3 think kidneys (metabollic)
PCO2 think lungs repiratory
What is it called when the blood pH is above 7.4? Below 7.4?
Above 7.4 = alkalemic
below 7.4 = Acidemic
What are the four situations in which your blood pH is affected and which direction will it affect you blood pH?
pH=HCO3/PCO2
Metabolic acidosis (kidneys) - pH goes down and HCO3 goes down
Metabolic alkalosis (kidneys)- pH goes up and HCO3 goes up
Respiratory acidosis (lungs)- pH goes down PCO2 goes up
Respiratory alkalosis (lungs)- pH goes up PCO2 goes down
How does the lungs respond to CO2?
Slow breathing- high CO2, low pH (acidoses)
Fast breathing - gets rid of CO High pH
What are the two ways to create an acidosis by bicarbonate?
Lose (decrease)HCO3- decrease pH (acidosis)
Use (decrease) HCO3- decrease pH (acidosis)-by the use of hydrogen ions
How does the body respond to a metabolic acidosis (decreased HCO3- causing a decresed pH)? Metabolic alkalosis increased HCO3- causing increased pH?
remember pH=HCO3/PCO2
Lungs will respond to correct pH back to 7.4
metabolic acidosis (decreased HCO3- causing a decresed pH)- this will cause a decrease in CO2 by the lungs (breathing faster)
metabolic alkalosis(incresed HCO3- causing a increased pH)- this will cause a increase in CO2 by the lungs (breathing slower)
fast process
How does the body respond in a respiratory acidosis (increased PCO2 causing a decreased pH)? Respiratory alkalosis decreased PCO2 causing a increased pH?
remember pH=HCO3/PCO2
Lungs will respond to correct pH back to 7.4
respiratory acidosis (increased PCO2 causing a decreased pH)- kidneys increase HCO3
Respiratory alkalosis decreased PCO2 causing a increased pH- kidneys decrease HCO3
slow process
What is the formula of how the lungs will respond to a metabolic acidosis?
Winters Formula-Metabolic Acidosis:
Expected pCO2 = 1.5 * [HCO3-]+ 8 (+/- 2)
What is the formula of how the lungs will respond to a metabolic alkalosis?
Metabolic Alkalosis:
Expected pCO2 = 0.7 [HCO3-] + 20 mmHg (range: +/- 5)
What is a anion gap acidosis?
an anion that is introduced into the system and brings a H+ with it. H+ depletes HCO3 casing acisosis
What are the important areas on a metabolic panel?
What does CO2 equal on the metabolic panel
First column is cations Na+/K+ second is anion CL-/CO2
CO2= HCO3
How is anion gap calculates?
What is a normal anion gap?
What is normal sodium?
Na - (Cl + HCO3(CO2)) = AG
Normal AG = 12
Normal Na = 140
What are the two types of metabolic acidosis? define them
Anion Gap metabolic acidosis (AGMA)- a anion brings in H+ and H+ is used with HCO3 this is called use. This creates a larger anion gap than normal because anion is added and H+ is being used with HCO3-
Non Anion Gap metabolic acidosis (NAGMA)- when metabolic acidosis is created because of loss of HCO3 no widened anion gap is created
Which metabolic processes that cam happen at the same time? what you cannot have?
(Use) AGMA and Metabolic alkalosis (retention) of HCO3
NAGMA and AGMA (use and lose)
NAGMA (loss of HCO3) and Metabolic alkalosis(retain of HCO3) cannot happen
What is the delta Gap? how do you calculate an delta gap?
Delta gap is a change Anions added to the blood
Calculated AG – Expected AG = Delta Gap
How do you determine which type of osis is going on?
1) Calculate the Anion Gap (AG)
2) Calculated AG – Expected AG = Delta Gap
Delta Gap + Measured HCO3-
If higher than 24 then metabolic Alkalosis (retain HCO3) along with AGMA(USE HCO3))
If less than 24 then NAGMA(loss of HCO3) with AGMA (use of HCO3)
Which ways in which a NAGMA (Loss of HCO3)?
GI
Pancreas
renal
How is a metabolic alkalosis created?
Retention of HCO3 by kidneys- only way
What are the steps to approaching acid base problems?
Determine if the blood is Acidemic or Alkalemic
Determine the direction in change of PCO2 and pH (up or down from normal values)
Primary Metabolic ( decrease pH decrease PCO2) vs. Primary Respiratory ( increase pH decrease PCO2)
Acidosis vs. Alkalosis
Calculate the Anion Gap
Compensation: PCO2 and HCO3; is there a mixed disorder
Winters formula: Expected pCO2 = 1.5 * HCO3- + 8 +/- 2
Metabolic Alkalosis: Expected pCO2 = 0.7 [HCO3] + 20 mmHg (range: +/- 5)
Delta Gap; Measured AG – Normal AG; then add to measured HCO3-
Map out your Differential Diagnosis
Treat underlying conditions unless pH in dangerous range, then treat with acute management.
