54R. Acids and Base balance and arterial blood gases Flashcards
what is the henderson hasselbalch equation
HCO3 + H+ = H2CO3 = CO2 + H2O
what is acidaemia
a state in which there is excess acid in the blood pH< 7.35
Acidaemia occurs when buffers cannot maintain a normal pH
what is acidosis
a state in which excess acid is being placed inside the system
so In summary, acidaemia is the result (acidic blood), while acidosis is the process (adding acid to the system). Acidosis can cause acidaemia if the body’s buffering capacity is exceeded.
Acidosis does not automatically lead to acidaemia (TRUE or FALSE)
True
what is Alkalosis
a state in which excess base is being placed inside the system
what is alkalaemia
a state in which there is excess base within the blood PH > 7.5
Alkalaemia occurs when buffers ……………..
cannot maintain a normal pH
Acid loss (vomiting)
name 3 physiological buffers
- proteins - Haemoglobin
- carbonic acid - Main blood pH buffer
- Ammonia - minor effects
when doing an arterial blood gas what are you measuring directly
pH
pO2
pCO2
does overcompensation occur - aka do the buffers sometimes overshoot
no
how fast is respiratory compensation (CO2 changes)
rapid
(Change to Minute Volume)
how fast is metabolic compensation (HCO3 changes)
slow
(Change to renal HCO3 production)
Respiratory Acidosis with Metabolic Compensation is common in what diseases
type 2 resp failure, COPD, CF, Kyphoscoliosis
Metabolic alkalosis with respiratory compensation is not common but what diseases does it occur in
Milk alkali syndrome, vomiting, severe hypokalaemia
Sepsis, DKA, poisoning, drugs, lactate is due to which? Select the correct combination of words
Respiratory/Metabolic
Acidosis/Alkalosis
with
Respiratory/Metabolic
compensation
Metabolic Acidosis with Respiratory compensation
Respiratory alkalosis with metabolic compensation is rare. what do you see it in?
Chronic hyper-ventilatory states…..
Uncompensated Respiratory Acidosis is what
Acute Type 2 Respiratory Failure
Compensated Respiratory Acidosis is what
Chronic Type 2 Respiratory Failure
Uncompensated Respiratory Acidosis and Compensated Respiratory Acidosis
what is the difference in diagnosis
Both Type 2 Respiratory Failure.
Compensated is chronic and uncompensated is acute
What is Decompensated Respiratory Acidosis
Decompensated Respiratory Acidosis occurs when a patient with chronic respiratory acidosis (chronic type 2 respiratory failure) experiences an acute worsening of their condition
what is the anion gap. And what does a high gap indicate
determines whether the acid in the system is being added (exogenous) or being redistributed (exogenous)
A high anion gap indicates the addition of acid, while a normal anion gap indicates redistribution.
what is the numonic for the causes of High anion gap acidosis
A MUD PILES
what does A MUD PILES all stand for when looking at causes for a high anion gap
Alcohol
Methanol
Uraemia
DKA
Paraquat
Infection
Lactic acid
Ethylene Glycol Salicylate
Salicylate (asprin)
what is the most common cause for a high anion gap
Infection
Localised tissue hypoxia leads to anerobic resp leads to Lactic acid production
what causes normal anion gap
Addison’s disease
High output fistulas (commonest)
Renal Tubular acidosis I, II, IV
Acetazolamide therapy
Diarrhea
Base Excess (BE) tells us if there’s too much acid or base in the blood.
It shows how much strong acid you need to add to the blood to bring the pH back to normal (7.4).
What is the amount of strong acid required to bring the pH back to 7.4, when CO2 is corrected to 5.3
BE > +2 = metabolic alkalosis
BE < -2 = metabolic acidosis
