Flashcards in L50 + 51 Deck (32)
What is compensation?
Development of a 2ary AB disorder to help correct the 1ary
Does compensation return the pH to normal?
If back to normal, you should suspect mixed
How do you get rid of H+ in the urine?
Carbonic anhydrase for bicarb reabsorption
To gain bicarb, you lose H
What does low PaCO2 mean practically?
Hypervent (1ary or 2ary)
CO2 = acid
Name the 4 steps of compensating for high H+ in the blood and the timeframe in which each occurs.
1. Buffer with bicarb in blood - immediate
2. Resp comp - mins
3. Intracell buffering - hrs
4. Renal H+ secretion - days
How is H+ secreted in urine?
If you have a metabolic acidosis and your urine is acidic, does that imply a renal or non-renal source of increased H+ produciton?
You're excreting protons as you should to increase your bicarb
If you have a metabolic acidosis and your urine is basic, does that imply a renal or non-renal source of increased H+?
1. Renal tubular acidosis = H+ secretion impaired so losing bicarb
2. Chronic kidney disease = ↓nephron #
What are the effects of metabolic acidosis on the body?
Hb/O2 curve shifts R = dissociation, more O2 delivered to tissues
What GI problem would cause a metabolic acidosis?
Diarrhea - losing bicarb
Formula for anion gap
Na - (HCO3 + Cl)
Acid minus the bases
Mudplies for anion gap metabolic acidosis
Ethylene glycol (anti-freeze look for oxalate)
Heart CCU for non-gap metabolic acidosis
Hyperalimentation (feeding tube)
Renal tubular acidosis
Carbonic anhydrase inhibitors
If you're normally reabsorbing bicarb in the kidney by excreting H into urine, where are you naturally compensating by doing the opposite?
Colon - bicarb into poop, reabsorb H
Why diarrhea loses bicarb -> acidosis
Describe the metabolic acidosis caused by renal tubular acidosis
- Urine pH
↑Cl metabolic acidosis
Urine pH not max acid (aka should be more acidic to compensate for acidosis)
Effects of metabolic alkalosis on the body
Left shift Hb/O2 curve: ↓O2 tissues
↓Cerebral blood flow
Extra-renal causes of metabolic alkalosis
1. Bicarb ingestion (antacids)
3. NG suctioning
Renal cause of metabolic alkalosis
What is the main difference between transient and maintained metabolic alkalosis?
1. Maintained: H+ secretion increased
Some stimulus to make prox tubule reclaim all the bicarb
2. Volume, Cl- or K+ depletion occurs during HCO3 loading
Why does volume depletion lend to akalosis?
Vol depleted - want to reabsorb Na
via Na/H exchanger
Must secrete H
Why does ↓Cl- lend to alkalosis?
Cl depleted - there is no Cl- in the urine to reabsorb
Conversion to mostly alpha intercalated cells = H secreting cells
Why does ↓K lend to alkalosis?
@ renal tubular cell
To reabsorb K, you have to secrete H to maintain electrical neutrality
When does Cl- loss and HCO3 load occur at the same time?
Lose Cl- from stomach acid
Therefore bicarb from the stomach rises
Look at image in slides
3 causes of transient metabolic alkalosis
1. Bicarb loading
Exogenous = tumor lysis syndrome
Endo = bone dissolution from immobility
2. Recovery from met acidosis
3. Post-hypercap resp acidosis
↓Cl- or vol depleted causes of persistent metabolic alkalosis
↓K causes of persistent metabolic acidosis
Renal failure due to ↓GFR
↓Cl- AND K causing metabolic alkalosis
Bartter's & Gitelman's
What does urine Cl tell you about a persistent metabolic alkalosis?
UCl 20 (norm) - check U K
What does urine K tell you about persistent metabolic alkalosis?
U K 20 = (high) renal/hyperaldo cause K
Is maintained metabolic acidosis associated with basic or acidic urine?
Maintained metabolic alkalosis associated with paradoxical aciduria
4 causes resp acidosis
Resp muscle dysfxn
Poor gas exchange