11.4: Acid / Alka Flashcards Preview

MHD V: Renal > 11.4: Acid / Alka > Flashcards

Flashcards in 11.4: Acid / Alka Deck (38):

What is metabolic acidosis?

- Decrease in bicarb [] in plasma
- Increases [H] plasma
- Accompanied by decrease in PCO2 to maintain PH
- Known as respiratory alkalosis


What is respiratory alkalosis?

- Decrease in PCO2 to normalize PH increase in metabolic acidosis


What is total CO2 / CO2 content?

What the chemistry lab calls bicarb when they measure it


What is the henderson Equation?

H+ = 24 PCO2 / HCO3-
***Want to keep hydrogen ion constant


Various [H] and PHs

7.1 = 80
7.2 = 63
7.3 = 51
7.4 = 40
7.5 = 32
7.6 = 25
7.7 = 20


Equation of acid base homeostasis?

H + HCO3- -> H2CO3 -> H20 + PCO2 (excreted by lungs)


What are the abnormalities with respiratory alk/acidosis in?

- PCO2
- Compensatory movement in bicarb


Predicted volume of compensation in alka / acid?

1.2 decrease bicarb = decrease in PCO2
.7 increase bicarb = increase in PCO2


What is electroneutrality?

- Anions in body must match volume of cations
- Na + UC = HCO3 + Cl + UA
- UC/A: unmeasured cations and anions


What is the anion gap?

- Na+, Cl-, and HCO3- are most prevalent ions
- DIfference between Na+ and Cl- + HCO3- is "anion gap"
- Anions must equal cations so no "real" gap
****Usually is 10 - 12


What does increased anion gap acidosis point to?

- Overproduction of an organic acid with retention of organic anion
- Organic acids are anions
- The acid is titrating the bicarb dropping its volume


2 causes and subclasses of increased anion gap acidosis?

Increase organic acid production
1. Ketoacidosis
2. Lactic acidosis
3. Toxin ingestion
Failure to excrete organic ions:
1. Renal failure


What is hyperchloremic acidosis?

- Bicarb is low, Cl- may increase to keep neutrality


Causes of Hyperchloremic acidosis?

1. GI loss of bicarb: diarrhea
2. Renal loss of bicarb: Renal tubular acidosis (RTA)
3. Failure to excrete acid: renal failure
4. Acid administration: TPN
5. High doses of saline


What is type II RTA?

"Renal Tubular acidosis" proximal tubule
- Impairment in HCO 3 reabsorption in proximal
- Bicarb begins to be spilled in urine at earlier level
-Causes acidosis in body with increased Cl- resorption with Na to neutralize HCO3 that was dumped
- Patient will have low serum bicarb and high Cl


What is Type I RTA?

- Inability to excrete H in distal tubule
- H ATPase normally pumps H out to combine with bicard
- This is impaired in RTA II


2 most common causes of hyperchloremic acidosis?

1. Diarrhea
2. Kidney disease


How treat metabolic acidosis?

Normal anion gap: bicarb
- Na or K / bicarb can be given as well
- Bicarb formers can be given as well


What is metabolic alkalosis?

- Increase in plasma bicarb
- Accompanied by increased PCO2 to maintain PH


Generation of metabolic alkalosis?

1. Net loss of H from ECF
2. Increased Bicarb to ECF
3. Loss of chloride in excess of bicarb


How can H be lost?

1. GI tract: vomit
2. Renal: in urine
3. Shift into cells


What happens to H in stomach?

- Titrate by pancreatic bicarb
- If H is lost in vomiting, net increase in bicarb


How is H lost in urine?

1. Excess mineralocorticoids: ADH (tumor)


What is mineralocorticoid in humans?



Why does H shift into cells?

- K moves out of cells in sever HYPOkalemia
- H moves in to replace charge


What can cause bicard gain?

1. Exogenous: bicarb, lactate, citrate, acetate
2. Chloride rich fluid loss: more bicarb resorbed


How is Cl lost in GI?

1. Villous adenoma: Cl secreting tumor into school
2. Failure of gut to resorb


Causes of renal chloride loss?

1. Diuretics: impair resorption
2. Bartter's syndrome: defect of K2Cl in loop
3. Gitelman's syndrome: defect in NACL cotransporter in distal


How is Cl lost in skin?

CF loss of Cl in excess of bicarb in sweat


How does kidney handle bicard?

- Freely filtered
- Reabsorbed in proximal nephron
- That consumed by acid is regenerated in distal


Reason for maintenance of metabolic alkalosis?

- Chloride depletion
- If you give solely Cl- back it corrects
- Usually given as NaCl


Why does chloride correct metabolic alkalosis?

- In type B intercalated cell, Cl moves into cell allowing bicarb to be dumped in urine to correct alkalosis


Signs of metabolic alkalosis?

1. Hypoventilation
2. Vomiting
3. Diuretics
4. Cramps
5. Htn.


What is low Cl in urine indicative of?

- Cl depletion


DD for metabolic alkalosis?

1. Chloride responsive: low Cl in urine
2. Chloride resistant: high Cl seen in urine: ADH excess state
- Extra Cl- will just be dumped in urine


How is metabolic alkalosis treated?

• Potassium administration
• Acetazolamide
• Volume repletion
• Intravenous HCl or NH4Cl


What is normal PCO2?



What is normal anion gap?

- 10 - 12
- If less than this when you calculate its normal anion gap
- If higher, high anion gap