Acid Base Management Flashcards
Lance Carter, C-AA
There are 5 main things that are measured with an arterial blood gas (ABG):
Additionally, depending on the lab, ABGs can also give the following results:
What is Base Excess?
What is the normal range for Base Excess?
What does negative base excess mean, and how is it treated?
What does positive base excess mean, and how is it treated?
Normal venous CO2?
Normal arterial HCO3-?
Normal PaCO2?
Normal PvCO2?
What causes increases in the PvCO2 to PaCO2 gradient?
Normal PaO2 of the atmosphere (at sea level)?
Normal PaO2 (partial pressure in arterial blood)?
Normal PvO2 (partial pressure in venous blood)?
Normal CaO2 (total oxygen content in arterial blood)?
Normal CvO2 (total oxygen content in venous blood)?
Normal mvO2 (mixed venous oxygen saturation)?
Normal SaO2 (O2 saturation in arterial blood)?
Normal ScvO2 (central venous oxygen saturation)?
Normal A-a gradient on room air?
Normal A-a gradient in elderly patients?
Normal A-a gradient on 100% FiO2?
Normal minute ventilation?
Normal Va (alveolar ventilation)?
Normal Vd (dead space ventilation)?
Normal VCO2 (CO2 production)?
Normal VO2 (oxygen consumption)?
Normal pH?
Normal %MetHb (methemoglobin) on ABG?
Normal %COHb (carboxyhemoglobin) on ABG?
Normal HCO3-/PaCO2 ratio?
Normal PaO2/FiO2 ratio?
Normal anion gap?
Normal base excess?
Normal serum lactate concentration?
Lactic acidosis is when serum lactate is greater than?
Explain the Carbonic Anhydrase Equation, and how CO2 affects acidosis?
Applying The Henderson Hasselbalch Equation (pH Equation) Clinically
Consequences of Acidosis
Consequences of Alkalosis
CaO2 Equation
CaO2 represents the total arterial oxygen content in the arteries, which includes:
Overall, what is the main idea behind the Ca02 equation?
What does the 1.34 and 0.003 mean in the Ca02 equation?
CvO2 Equation
Fick Equation
(For Oxygen Consumption & Cardiac Output)
What is the DO2 Equation?
Pressure Of Inspired Oxygen (PiO2) Equation
Alveolar Gas Equation (PAO2 Equation)
How The Alveolar Gas (PAO2) Equation Is Derived
Take Home Points From The PAO2 Equation
PAO2 increases if PaCO2 _________?
PAO2 increases if PaCO2 decreases
PAO2 is primarily determined by ____?
PAO2 is primarily determined by FiO2
The estimation for PaO2 is:
What does an A-a gradient tell us?
Factors That Can INCREASE The A-a Gradient
Disadvantages/Limitations To Utilizing The A-a Gradient
What is the PaO2/FiO2 Ratio?
What is a normal PaO2/FiO2 Ratio?
“…a PaO2/FiO2 ratio of less than ___ indicates acute lung injury (ALI)?”
“…a PaO2/FiO2 ratio of less than 300 indicates acute lung injury (ALI)”
PaO2/FiO2 ratio of less than ___ is diagnostic of ARDS
PaO2/FiO2 ratio of less than 200 is diagnostic of ARDS
There are two advantages to using the PaO2/FiO2 over the A-a gradient:
Carbonic Anhydrase Equation
The 3 Different Forms Of CO2 In The Body:
What form of CO2 is dissolved in the plasma? How much of total CO2 does it account for?
The 3 Different Forms of CO2 in the Body:
The second form of CO2 in the body is _____ that is dissolved in the plasma
How much of CO2 in the body exists as HCO3-? What is the normal HCO3- to PaCO2 ratio?
The 3 Different Forms of CO2 in the body:
The third form of CO2 in the body is _____ that is attached to hemoglobin
Venous labs can be referred to as?
CO2/HCO3- In Venous Labs is represented by?
The reason that a venous CO2 result can be listed as either “HCO3-” or “CO2” is?
Normal Venous CO2?
Normal value for arterial HCO3- is?
Difference between CO2/HCO3- In Arterial Labs?
Tidal volume (Vt) refers to?
Dead space (Vd) volume refers to?
Equation for Minute Ventilation (MV)?
Equation for Alveolar Ventilation (Va), and what does it represent?
1st Equation For Alveolar Ventilation (Va)
2nd Equation For Alveolar Ventilation (Va)
Dead Space Ventilation (Vd/Vt)?
1st Equation For Dead Space Ventilation (Vd/Vt)
2nd Equation For Dead Space Ventilation (Vd/Vt)
PaCO2 Equation
What does the PaCO2 Equation predict?
Higher the starting PaCO2, the more it will change for a given decrease in alveolar ventilation. True or False.
True
Bohr Effect
Haldane Effect
Venous Admixture
(Pulmonary Shunt)
How does hyper/hypoventillation differ from respiratory rate?
What is the difference between hypoxia and hypoxemia?
Cause of respiratory acidosis?
If both [H+] (an acid) and [HCO3-] (a base) increase by the same amount, how does the pH go down? Why doesn’t the pH remain unchanged?
- The first reason that pH decreases in respiratory acidosis is that the number of H+ ions increases, and when we defined pH, we said that more H+ ions equals a lower pH (acidosis). Period.
- The second reason that pH decreases in respiratory acidosis is that, although PaCO2 (an acid) and HCO3- (a base) both increase, PaCO2 increases by a greater percentage
Diagnosing respiratory acidosis
- A low pH
- A high PaCO2
The Problem With Respiratory Acidosis
Treatment For Respiratory Acidosis
Respiratory alkalosis
Why pH Increases In Respiratory Alkalosis
- The first reason that pH decreases in respiratory alkalosis is that the number of H+ ions decreases, and when we defined pH, we said that less H+ ions equals a higher pH (alkalosis)
- The second reason that pH increases in respiratory alkalosis is that, although PaCO2 (an acid) and HCO3- (a base) both decrease, PaCO2 decreases by a greater percentage
Diagnosis of respiratory alkalosis
- A high pH, and
- A low PaCO2
The Problem With Respiratory Alkalosis
Treatment For Respiratory Alkalosis
Metabolic Acidosis
Possible Mechanisms of Metabolic Acidosis
- Metabolic acidosis can occur from a DIRECT loss of HCO3-
- An example would be a direct GI loss of HCO3- through diarrhea - Metabolic acidosis can also occur from an increase in acid (H+)
- The excess H+ binds HCO3-, which causes an INDIRECT loss of HCO3-
Examples include lactic acidosis & diabetic ketoacidosis
Why pH Decreases In Metabolic Acidosis
Diagnosis Of Metabolic Acidosis
The Problem With Metabolic Acidosis
The Problem With Metabolic Acidosis
Sodium Bicarb Dose
Question:
Metabolic Alkalosis
Possible Mechanisms of Metabolic Alkalosis
- Metabolic alkalosis can occur if there is a direct loss of acid (H+) in the body
- Examples include vomiting, diuretics, gastric drainage, etc
- When the [H+] is lost, more HCO3- is available because less of it is bound by H+ - Metabolic alkalosis can also occur if there is a buildup of HCO3- in the body
- An example would be a massive blood transfusion, where the citrate preservative is converted to HCO3-
- The excess HCO3- binds H+ ions and reduces the H+ concentration
- So, remember that massive blood transfusion can cause metabolic alkalosis
Why pH Increases In Metabolic Alkalosis
Diagnosis of Metabolic Alkalosis
- A high pH
- A high HCO3-
The Problem With Metabolic Alkalosis
The problem with metabolic alkalosis is that we have too few H+ ions (which is causing the pH to be too high)
–Therefore, if the body is going to normalize the pH, it has to “compensate” and come up with a way to increase the number of H+ ions…
Treatment For Metabolic Alkalosis
Acid Base Compensation Summary
Lactic Acidosis
Why does lactic acidosis occur?
Causes of sepsis:
Treatment of sepsis:
Out of all the listed cations and anions, which ones are routinely measured when venous labs are drawn?
Normal values:
Anion Gap
2 Ways To Calculate The Anion Gap
How Anion Gap Is Calculated
Normal anion gap
Reasons why the anion gap would increase:
Reasons why the anion gap would decrease:
High (Elevated/Widened) Anion Gap
Question:
Causes of normal anion gap:
What happens with the anion gap with hyperchloremic metabolic acidosis?
Causes of Low (Narrow) Anion Gap:
