Approach to Acid/Base (Selby) Flashcards Preview

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Flashcards in Approach to Acid/Base (Selby) Deck (52)
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1
Q

What kind of disturbances exist in Metabolic Acidosis

A
HAGMA
NAGMA (hypercholermic acidosis)
2
Q

What kind of disturbances exist in Metabolic Alkalosis

A

Salie-Responsiveness (hypovolemia… contraction alkalosis or chloride deficiency alkalosis)

Saline-on-Responsive (euvolemia)

3
Q

What kind of disturbances exist Respiratory Acidosis

A

Acute

Chronic

4
Q

What kind of disturbances exist Respiratory Alkalosis

A

Acute

Chronic

5
Q

Metabolic Acidosis formula

A

Winter’s formula

PCO2 = 1.5[HCO3] + 8 +/- 2

6
Q

Metabolic Alkalosis formula

A

PCO2 will increase by 0.7 for each 1.0 increase in HCO3 above 24

ΔPCO2 = ([HCO3] - 24) * 0.7

7
Q

Respiratory Acidosis Acute Formula

A

HCO3 will increase by 1 for every 10 increase in PCO2 above 40

ΔHCO3 = (CO2-40) * 0.1

8
Q

Respiratory Acidosis Chronic Formula

A

HCO3 will increase by 3.5 for every 10 increase in PCO2 above 40

ΔHCO3 = (CO2-40) * 0.35

9
Q

Respiratory Alkalosis Acute formula

A

HCO3 will decrease by 2 for every 10 decrease in PCO2 above 40

ΔHCO3 = (CO2-40) * -0.2

10
Q

Respiratory Alkalosis Chronic formula

A

HCO3 will decrease by 5 for every 10 decrease in PCO2 above 40

ΔHCO3 = (CO2-40) * -0.5

11
Q

Normal Anion Gap

A

12 +/- 2

12
Q

Paraproteinemias present as

A

low anion gap values

13
Q

lithium/bromide/iodide toxications present as

A

low or even negative anion gap values

14
Q

Anion Gap formula

A

Na - (HCO3 + Cl-)

15
Q

RTA or diarrhea present as

A

NAGMA

16
Q

For every 1 g/dL drop in Albumin AG changes by

A

drops 2.5

17
Q

If AG is calculated as 12 but serum albumin is 2 lower than normal what is the real AG

A

17

18
Q

Serum osmolality calculation

A

2(Na) + (Glucose/18) + (BUN/2.8)

19
Q

Osmolar Gap

A

Calculated osm - measured osm

20
Q

normal osmolar gap

A

<10

21
Q

if AG is 20

A

suspect alcohol ingestion

22
Q

Delta - Delta Gap calculation

A
calculated AG(x) - normal AG(12)
Delta HCO3 == normal HCO3 (24) - calculated delta gap

so

x-12 = y 
24-y= delta gap
23
Q

if measured HCO3 was close to 16 in delta detla

A

no additional acid base present

24
Q

if measured HCO3 was >16 in delta delta

A

then additional metabolic alkalosis is present in addtion to HAGMA

25
Q

if measured HCO3 <16 in delta detla

A

non-gap metabolic acidosis is present in addition to HAGMA

26
Q

what is acidosis

A

pH <7.35

27
Q

what is alkalosis

A

pH >7.44

28
Q

normal HCO3

A

24

29
Q

normal PCO2

A

40

30
Q

normal anion gap

A

12

31
Q

normal osmolar gap

A

10

32
Q

HAGMA differential

A
GOLD MARK
Glycols (ethylene and propylene)
Oxoproline (acetaminophen toxicity)
L-lactic acidosis
D-lactic acidosis (colonic matbolization of glucose and seen in short bowel syndrome)

Methanol
Aspirin
Renal failure
Ketoacidosis (alcoholic, diabetic, starvation)

33
Q

pyroglutamic acidosis

A

more in women who are malnourished or critically ill

seen through urinary organic acid screen

treated with halting of acetaminophen/IVF/N-acetylcysteine

34
Q

DDx for increased osmolar gap

A

ME DIE

Methanol
Ethanol

Diethylene glycol (mannitol)
Isopropyl alcohol (not associated with met acidosis)
Ethylene glycol

ketoacidosis and lactic acidosis smaller increase in osmolar gap

35
Q

NAGMA DDx

A

DURHAAM

he said the three we need to know are
Diarrhea
Ureteral diversion (ileal conduit)
Renal tubular Acidosis

Hyperalimentation
Acetazolamide
Addison’s disease
Miscellaneous (glue sniffing sits here… pancreatic fistula, medications)

36
Q

Proximal RTA (type 2)

A

decreased in capacity of PT to reabsorb HCO3

loss of HCO3 in urine because the TAL and DT cannot compensate creating acidosis

eventually the serum HCO3 will decrease and PT/TAL/DT are no longer overhwlemed and a new steady state develops

37
Q

Proximal RTA (type 2) etiology in kids

A

most common cause in kids is cystinosis

38
Q

Proximal RTA (type 2) etiology in adults

A

most common cause in adults is falconi syndrome and secondary is multiple myeloma

39
Q

clinical manifestation of proximal RTA (type 2)

A

NAGMA with or without proximal tubular dysfunction

hypokalemia which is milder than distal RTA (type 1)

40
Q

diagnosis of proximal RTA (type 2)

A

urine pH can be high or low depending on serum HCO3

urine ph <5.5 when in new steady state

UAG can be positive or negative

41
Q

Urine Anion Gap

A

used to determine if renal or non-renal in NAGMA

NH4Cl excretion which indicated appropriate urinary acidification… but most labs don’t measure this

UAG = (UrineNa + Urine K+) - Urine Cl

42
Q

if UAG is negative

A

indicated appropriate distal nephron urinary acidification

43
Q

if UAG is positive

A

indicates inappropriate distal nephron urinary acidification

44
Q

Distal RTA (Type 1)

A

Pts are unable to acidify their urine

decreased H+ ion secretion

gradient defect can be caused by amphotericin or fungal infections

lack of H+ secretion prevents acidification and excretion of ammonium leading to prevention of HCO3 reabsorption in distal tubule

45
Q

Distal RTA (Type 1) etiology and manifestation

A

can be primary/acquired

commonly seen with Sjogren’s Syndrome

Glue sniffing another common cause due to toluene

associated with nephrolithiasis or nephrocalcinosis

46
Q

Distal RTA (Type 1) diagnosis

A

NAGMA

unable to acidify urine pH <5.5

Hypokalemia from urinary K wasting

UAG is positive

47
Q

Hyperkalemic RTA (Type 4)

A

Dysfunction from impaired excretion of H+ and K causing NAGMA/Hyperkalemia

Deficiecy of circulating Aldosterone (DM and NSAIDs/Beta blockers/ACEi/Heparin)

Aldosterone resistance in CD (interstitial renal disease such as sickle cell/obstructive uropathy/lupus or drugs including amiloride/triameterene/spironolactone/trimethoprim)

impaired Na reabsorpion and resulting hyperkalemia

48
Q

Hyperkalemic RTA (Type 4) clinical manifestation and diagnosis

A

usually asymptomatic/NAGMA/hyperkalemia

patients are normally 50-70 with history of diabetes or CKD

diagnosis
urine pH>5.5
UAG positive

49
Q

Metabolic Alkalosis DDx

A
5 important ones
Hypokalemia
Vomiting/nasogastric tube suctioning
diuretics
volume depletion
Mineralocorticoid excess
secondarily
Bartter and gielman
posthypercapnic alkalosis
hypercalcemia/milk-alkali syndrome
diarrhea (rarely)
50
Q

Respiratory Alkalosis DDx

A

anything that increases respiratory rate or Tidal Volume

there’s a big table

51
Q

Respiratory Acidosis DDx

A

anything that lowers respiratory rate/tidal volume, increses dead space, or worsens an obstruction

inadequate ventilator setting can increase CO2 production

(there’s a big list in the slideshow)

52
Q

Acid-Base Stepwise Approach

A

Determine if Acidosis or Alkalosis

determine if primary disturbance is metabolic or respiratory

calculate anion gap if met acidosis is present

calculate appropriate compensation for primary acid-base disorder