Cremo Simple Acid Base Disturbances Flashcards
(65 cards)
What determines if a patient is acidemic or alkalemic?
Acidemic: pH7.45
If you are acidemic how can you tell if you are in metabolic acidosis or respiratory acidosis?
Metabolic Acidosis: HCO3-40
If you have metabolic acidosis, how can you tell if you have non gap acidosis or gap acidosis?
Non Gap Acidosis: Anion Gap 12
If you have alkalemia how can you tell if you have respiratory alkalosis or metabolic alkalosis?
Metabolic Alkalosis: HCO3- > 24
Respiratory Alkalosis: PaCO2 < 40
If you have respiratory acidosis or respiratory alkalosis how can you tell if it is acute or chronic?
If PCO2>10mmHg: & the pH < 0.8: acute
If PCO2 >10mmHg: & the pH < 0.3 chronic
If PCO2 0.8 acute
If PCO2 0.3 chronic
What is the difference b/w acidemia & alkalemia vs. acidosis & alkalosis?
Emia refers to the H+ conc’n in the blood
Osis refers a pathological condition–what causes the emia.
What causes respiratory acidosis or alkalosis?
Pathological changes in PaCO2.
- *usu caused by problems with lungs
- *sometimes caused w/ CO2 poisoning & normal lungs
What causes metabolic acidosis or alkalosis?
pathological changes in bicarbonate
Every point on a Davenport Diagram is equal to what?
a solution to the Henderson-Hasselbach equation…
What happens when you increase PaCO2?
H+ & bicarbonate will rise too.
What is the line called that represents the same CO2 on a Davenport Diagram? An increase in CO2 will cause a shift of the line in which direction?
an isopleth
a shift inward
What does the presence of Hb do to an increase in CO2? What is this called?
It binds to the H+ and takes them out of circulation. This lessens the increase in conc’n of H+ when you add CO2.
Called a non-volatile buffer
What do non-volatile buffers buffer?
CO2 changes. Ex: Hb
What is the slope of Davenport? What does it represent?
It is the slope of the buffer line of blood. The line that is made if you connect the changes in bicarbonate conc’n of all of the isopleths.
It reflects the responsive change of bicarbonate.
If you have more nonvolatile buffer available…what does that do to the buffer line in the Davenport diagram?
It makes it more steep.
Ultimately, there is more bicarbonate available at lower pHs.
When you get respiratory acidosis–what changes? What line do you move along?
PaCO2 changes. So you move onto a different isopleth.
You move along the buffer line of blood.
What does acute mean?
It means that it happened minutes or hours ago. It means that the renal system hasn’t had time to buffer it.
What type of ventilation would acute respiratory acidosis correspond to?
Hypoventilation
In acute respiratory acidosis–>what wins: strength or load?
Load.
Airflow Resistance
Lung Stiffness
Ventilatory Requirement
What are pulmonary explanations for acute respiratory acidosis?
Upper Airway Obstruction: swallow toy car Severe Asthma attack COPD Severe pneumonia Severe pulmonary edema
What are non-pulmonary explanations for acute respiratory acidosis?
Disruption in the neural linkage that drives breathing…
Central nervous system depression
External environment preventing normal breathing
What are 2 examples that cause a central nervous system depression? What is an explanation for an external environment preventing normal breathing?
Central Nervous System Depression: drug overdose or anesthesia
External Environment Preventing Normal Breathing: heavy weight on chest
Respiratory Alkalosis corresponds to what line shift? What line movement?
Line Shift to a different isopleth. One with a lower PCO2.
This is movement to the right on the buffer line of blood. This corresponds with a small decrease in HCO3-.
What is the role of nonvolatile buffers in respiratory alkalosis?
As the CO2 decreases…there is a shift that lessens the amount of HCO3- & H+. But the Hb that is holding onto H+ will let go of some of it & prevent a dramatic decrease in hydrogen ions.
