When acid/base balance is disrupted, compensation must occur. What are the two rules that accompany this compensation process?
- Compensation will never get me to exactly normal
- compensation must be made by the other system
Ex: if metabolism is compromized and my pH changes as a result, the respiratory system must compensate
What happens if there is an increase in H ions (decreased pH) in the blood?
Increase ventilation and blow off CO2
this reduces PaCO2 and brings pH back up
If there is a decrease in H in the blood (increased pH) what happens?
Decrease ventilation and retain CO2
this will increase PaCO2 and bring pH down
What are the steps to determine if someone has respiratory or metabolic acidosis or alkalosis?
- look at pH: less than or more than 7.4
- Look at CO2 and HCO3
- Respiratory: CO2 and pH change in opposite directions
- Metabolic: Bicarb and pH change in same direction
- MATH
Why do we ask of compensation is “adequate”
- respiratory response will be very quick and occur before the condition can be considered chronic
- the respiratory system can only influence a small part of the total HCO3, so it never gets the pHa as close to normal as might be expected
What can change HCO3 ?`
kidneys because they can kick HCO3 into urine or H into urine (can’t happen if kidneys are broken)
GI tract secretes HCO3 or H. Can lose HCO3 if V/D
TUMs (too much bicarb?)
Making your own Acids (lactic acid, ketoacid)
How do we know if acidosis is from making our own (metabolic acidosis?)
Calculate Anion Gap
Na-(Cl+HCO3)
positives and negatives should always balance themselves out (should be <12)
Keep in mind that bicarb can buffer the acid, so pH might not be as acidic as you would think and will lose bicarb, making positives and negatives not balance out
An elevated anion gap indicates unmeasured chemicals such as
GOLDMARK or MUDPILES
Methanol
Uremia
DKA, starvation or ETOH ketoacidosis
Paraldehyde
Isoniazid/Iron
Ethylene Glycol or ETOH
Salicylates
