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Spr2015_Week9 > Acid/Base Disorder > Flashcards

Acid/Base Disorder Flashcards

1
Q

Acidity equation

A

Acidity = Bicarb/Carbon Dioxide

pH = [HCO3-] / [CO2]

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2
Q

if HCO3- incr, what is pH change and what disease

A

incr pH

metabolic alkalosis

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3
Q

if HCO3- decr, what is pH change and what disease

A

Decr pH

Metabolic acidosis

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4
Q

if pCO2 incr, what is pH change and what disease

A

decr pH

respiratory acidosis

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5
Q

if pCO2 decr, what is pH change and what disease

A

incr pH

respiratory alkalosis

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6
Q

if compensation is not as expected, then…

A

additional acid base disorder present

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7
Q

Compensation is ALWAYS in …

A

same direction as primary change

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8
Q

Compensation for metabolic acid-base disorders

Compensation for respiratory acid-base disorders

A

1) change in PCO2 in same direction as bicarb to bring pH back to normal
2) change in bicarb in same direction as PCO2 to bring pH back to normal

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9
Q

Changes in PCO2 are controlled by …

Changes in HCO3- are controlled by …

A

1) lungs
2) kidney

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10
Q

Metabolic acidosis compensation rule

Metabolic alkalosis compensation rule

A

1) deltaPCO2 = 1 to 1.5 x deltaHCO3-
2) deltaPCO2 = 0.7 x deltaHCO3-

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11
Q

metabolic-kidney compensation

Respiratory acidosis

acute compensation

chronic compensation

Respiratory alkalosis

acute compensation

chronic compensation

A

1) deltaHCO3- = incr 1:10 PCO2

deltaHCO3- = incr 4:10 PCO2

2) deltaHCO3- = decr 2:10 PCO2

deltaHCO3- = decr 4:10 PCO2

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12
Q

Causes of respiratory alkalosis ALWAYS DUE TO

A

HYPERVENTILATION (breathing too much)

  • Anxiety, fever, pain
  • Lung disease
  • Liver disease
  • Sepsis
  • Brain disease
  • Pregnancy (progesterone)
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13
Q

Acute respiratory alkalosis is before

Chronic respiratory alkalosis occurs __ after acute

A

renal compensation

3-5 days

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14
Q

Case: 21 y/o female in the ER

c/o Shortness of breath, chest pain
Wheezing on exam
pH=7.5; PCO2= 20; HCO3= 20; PaO2=80

(normal: pH: 7.4; PCO2: 40; HCO3 24)

ACUTE OR CHRONIC RESPIRATORY ALKALOSIS

A

ACUTE COMPENSATION

If acute, HCO3 should ↓ 2 x 2 = 4 and expected

HCO3 is 24-4 = 20

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15
Q

RESPIRATORY acidosis is due to

A

breathing too little (CO2 retention)

1) brain injury, narcotics, hypothyroidism,
2) aspiratory of foreign bodies
3) hypokalemia, hypophosphatemia, muscle fatigue
4) pneumonia, COPD, ILD

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16
Q

21 y/o female in ER

c/o Shortness of breath, chest pain
Wheezing
pH=7.3; PCO2= 50; HCO3= 25; PaO2=58

(normal: pH: 7.4; PCO2: 40; HCO3 24)

acute or chronic?

A

acute respiratory acidosis

What is expected increase in HCO3 ?
PCO2 has increased by 1 x 10.

If acute, increase in HCO3 is 1 x 1, 24+1= 25

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17
Q

what does mineralocorticoid normally do?

what does it cause?

A

mineralocorticoids cause secretion of H+ ion
and reabsorb HCO3-

respiratory alkalosis

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18
Q

Metabolic alkalosis causes

A

GENERATION

Addition of HCO3- = (Ringers, packed RBCs, total parenteral nutrition)

Contraction alkalosis = loss of Cl-rich (HCO3- poor fluid) = vomiting, NG suction, diuretics (HCTZ, loop)

Loss H+ (vomiting (HCO3- stays behind), mineralocorticoids and diuretics )

post hypercapneia

hypokalemia

MAINTENANCE

inability to excrete excess bicarbonate (ALWAYS KIDNEY FAULT)

19
Q

Metabolic alkalosis = Generation

A

Mineralocorticoids cause H+ excretion via H+ ATPase

and causes HCO3- resorption = mineralocorticoids and diuretics

20
Q

Causes of excess mineralocorticoids

(incr renal H+ excretion, incr mineralocorticoids)

A

1) primary hyperaldosteronism

2) Cushing’s syndrome
3) congenital adrenal hyperplasia

4) hyperreninism
5) renal artery stenosis

21
Q

Maintenance of metabolic alkalosis is ___

Causes?

A

ALWAYS KIDNEY’S FAULT (INABILITY TO EXCRETE HCO3-)

1) excess mineralocorticoid activity

2) hypovolemia
3) chloride depletion and K+ depletion –> impairs HCO3 excretion

22
Q

Maintenance of metabolic alkalosis

causes

A

Hypovolemia causes … Na+ resorption

Na+ resorption causes …HCO3- and Cl- resorption

Excess mineralocorticoid activity

23
Q

Metabolic alkalosis

if urine Cl is low < 20

A

described as metabolic alkalosis chloride responsive

with hypovolemia as maintenance factor

1) contraction alkalosis
2) addition of bicarb
3) GI H+ loss
4) Renal H+ loss

24
Q

metabolic alkalosis

if urine Cl is high > 20

A

chloride resistant
= chloride depletion with hypovolemia is not the maintenance factor

1) hypertensive = excess mineralocorticoid activity
2) normotensive= intracellular H+ loss

3)

25
Q
A
26
Q

Compensation for metabolic alkalosis
by body

A

PCO2 incr by hypoventilation

max PCO2 = 55 in acute and 60-70 in chronic

deltaPCO2 = 0.7 x deltaHCO3-

27
Q

July 4th picnic, vomiting x 24 hrs, BP 90/40, HR125

c/o dizziness, nausea, can’teat/drink
pH7.5; PCO2:50 ;HCO3-:34

(nl:7.4/40/24)

UrineNa: 25;

UrineCl: 9

what does she have

how do you treat her

compensation?

A

primary disorder = metabolic alkalosis
with appropriate respiratory compensation

ALWAYS GET URINE CHLORIDE)

Because urine chloride < 10 –> chloride responsive –> give her NS since low BP and vomiting

deltaPCO2 = 0.7 x 10= 7

pCO2 = 40 + 7 = 47

28
Q
A
29
Q

metabolic acidosis

Each day the kidney has to deal with ___ mEq of H+ which consumes ___ of HCO3-

A

60 mEq of H+

consumes 60 mEq of HCo3-

drives reaction to H2O and CO2

30
Q

handling daily acid load

in proximal tubule…

in distal tubule…

A

1) reabsorb HCO3-
2) secrete H+, make HCo3-, acidify urine, excrete daily acid load (want to get H+ ion into lumen and reabsorb HCO3-)

secrete 60 H+ means make 60 HCO3-

31
Q

Proximal tubule reabsorption mechanisms

A

Glucose reabsorbs using energy from Na/K atpase so don’t pee out

32
Q

Fate of secreted H+

2 mechanisms for neutralizing acid

A

1) TA- HPO4- + H+ –> H2PO4-
2) Ammonia trapping- NH3 + H+ = NH4+

33
Q

Failure of kidney to handle daily acid load –> ____

Proximal =

Distal =

A

metabolic acidosis = renal tubular acidosis

proximal = failure to reabsorb HCO3-

distal = failure to secrete H+ and make HCO3-

34
Q

urine anion gap is positive when ___

A

distal kidney problem = failure to secrete H+ and reabsorb HCO3-

35
Q

if metabolic acidosis problem is renal, then urine anion gap is ____

if metabolic acidosis problem is GI (diarrhea, surg drains, fistulas), urine anion gap is ___

A

1) positive
2) negative

36
Q

Normal anion gap calculation

Adjust down by 2.5 for every ___

A

Na - HCO3- - Cl- = 9 +/- 3

1 mg/dL decr in albumin

37
Q

With the loss of HCO3-, compensate by

A

incr Cl- so UAG is same

38
Q

4th of July picnic, diarrhea for 3 days

! pH: 7.2; PCO2: 26; HCO3- : 10

! Serum Na: 140; Cl: 120; HCO3- : 10

! Urine Na: 10; Urine K: 10; Urine Cl: 40

serum anion gap = ?

urine anion gap = ?

deltaPCO2 = ?

A

serum anion gap = 10 (normal)

urine anion gap = -20 (negative = GI cause)

deltaPCO2 = 1 to 1.5 x deltaHCO3- = 26

39
Q

Bicarbonate loss causes anion gap to be ___

addition of acid causes anion gap to be ___

A

to be normal

to be increased

40
Q

Causes of H+ anions to be added

A

! Ketones(Metabolism) – Starvation (ketones)
– DKA (ketones)

! AspirinandotherToxins/Ingestions

– Ethylene glycol (-> -> glycolic acid -> -> oxalic acid)

– Methanol (formaldehyde -> formic acid)

– Ethanol (ketones)

– Aspirin (Acetylsalicylic acid -> salicylic acid)

! Renalfailure(sulfate,urate,phosphate,hippurate) ! Lacticacid(Hypoxia)

41
Q

normal values

pH

pco2

HCO3-

A

7.40

40

24

42
Q

compensation resp alkalosis 2 steps

compensation resp acidosis 2 steps

metabolic alkalosis

A

1) cell H+ release (acute
2) renal H+ retention (chronic

___

1) cell buffering = H+ abs by cell buffers
2) renal H+ excretion–> makes new HCO3

43
Q

in appropriately compensated resp acidosis, pH does not fall below ___

A

7.20

Spr2015_Week9 (10 decks)

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