Metabolic Acidosis

Newer mnemonic for gapped acidosis:

"GOLDMARK" G - G-Glycols - ethylene, propylene O - 5-Oxyprolene (metabolite of acetaminophen intoxication) L - L-lactic acidosis D - D-lactic acidosis (short gut syndrome) M - Methanol A - Aspirin R - Renal failure (Uremia) K - Ketosis - diabetic, alcoholic, starvation

Non-gapped (losing bicarb) mnemonic:

"HARDUP" (loss of BICARB) Hyperalimentation, Hyperchloremia Acetazolamide, Addison's Renal tubular acidosis - Types I, II, and IV Diarrhea Ureterosigmoid fistula Pancreatic fistula

Formula for Delta Delta?

(Patients Anion Gap - 10 / 24 - patient's bicarb)

Case 4: A 50 year old WF with a history of Crohn's disease comes in for diarrhea x 6 days. She is admitted for treatment of a Crohn's flare. Admission blood work: Na+ 130, Cl- 102, HCO3- 18, K+ 4.2, Glc 120 ABG: 7.3/ *CO2 = 34*/90 What is/are the acid base disturbance(s)?

*Non-gapped acidosis b/c diarrhea* Anion gap = 130 - (120+18) = 8 This is a Normal anion gap since <8. Winter's Formula = 33-37 pCo2 in this case is 34 so since it falls in the correct range, there is no respiratory compensation

You have a metabolic acidosis if the bicarb (HCO3-) is below ___:

24

If Delta Delta is =1 what do you have? a. pure anion-gap metabolic acidosis b. metabolic alkalosis c. respiratory acidosis d. respiratory alkilosis e. non-gapped acidosis

A

Pathologic disturbance characterized by low arterial pH (increased H+ concentration) with decreased plasma HCO3- concentration is known as: a. acidosis b. alkalosis c. acidemia d. alkalemia

A (the process)

When would you suspect an osmolar gap?

Alcohol poisoning

If Delta Delta is >1 what do you have? a. pure anion-gap metabolic acidosis b. metabolic alkalosis c. respiratory acidosis d. respiratory alkilosis e. non-gapped acidosis

B

If Winter's formula is higher than expected, then you'd also expect a ______ to be present (hypoventilation) a. metabolic acidosis b. metabolic alkalosis c. respiratory acidosis b. respiratory alkalosis

C

pH <7.35 defines: a. acidosis b. alkalosis c. acidemia d. alkalemia

C (just by definition)

*Antifreeze* on histology is confirmed by the presence of:

Calcium Oxalate Crystals

Case #3

Calculated Serum Osm 326 Osmolar gap = 356 - 326 = 30 (normal 10 or less) Would suspect toxic alcohol ingestion i.e. methanol, ethylene glycol, propylene glycol

Which will NOT cause an anionic gap? a. Ethylene glycol converted to oxalic acid b. Methanol converted to formic acid c. Propylene glycol converted to pyruvic acid, acetic acid, lactic acid, propionaldehyde d. isopropyl (rubbing) alcohol

D (does NOT produce an anion gap but DOES cause an osmolar gap)

If Delta Delta is <1 what do you have? a. pure anion-gap metabolic acidosis b. metabolic alkalosis c. respiratory acidosis d. respiratory alkilosis e. non-gapped acidosis

E

CASE 1: 22 year old man with a history of DM Type 1 comes to ER with a 3-day history of nausea and vomiting Admission blood work: Na+ 130, Cl- 96, HCO3- 16, K+ 5.3, Glc 450 What acid base disturbance is present? What is the anion gap? What other information do you need?

Gapped (b/c diabetes) Metabolic Acidosis (Anion Gap = (= Na+ - (Cl- + HCO3-) = normal is between 6 and 12 depending on the lab) = 130 - (96+16) = 130 - 112 = 18 = higher than 12, so metabolic acidosis) Winter's formula = pCO2 = [(1.5 x Bicarbonate) + 8] +/- 2 = 1.5(16) + 8 +/- 2 = 30-34 WF = 30-34, and blood work pCO2 = 33 so respiratory is fine. no respiratory alkalosis Delta Delta = 18 - 10 = 8 WF = 24-16 = 1 DD = 8/8 = 1 Anion gap = 130 - (96 + 16) = 18 Δ/Δ = (Patients Anion Gap - 10 / 24 - patient's bicarb) = (18-10)/(24-16) = 8/8 = 1. Since = 1 Pure anion gap metabolic acidosis

The patient is treated for DKA with insulin and IV fluids (normal saline). DKA resolves. BMP after 24 hours shows the following: Na 138, Cl- 110, HCO3- 20, K+ 4, Glc 140 What is the disturbance? How did this develop?

Non-gapped acidosis (b/c saline = hydrochloremia) (138 - (110+20)) = 8

Why might you find an osmolar gap in the beginning, but an anion gap after a few hours?

Osmolar and anion gap over time with toxic alcohol ingestion

What is the equation for Winter's Formula?

P(CO2) = (1.5 x Bicarb) + 8 +/- 2 (If the measured PCO2 is higher than the calculated value, there is also a primary respiratory acidosis.)

_____ cause *both an anion gapped metabolic acidosis AND respiratory alkalosis*

Salicylates (Aspirin)

Intoxications with high anion gaps

Toxic alcohols cause an osmolar gap and their byproducts increase anion gap Osmolar gap created by an unmeasured osmole in the blood stream = Measured osmolality - calculated osmolality Should be less than 10-15 > 10 may be indicative of an alcohol intoxication Calculated osmolality = 2 Na+ + Glc/18 + BUN/2.8 + Ethanol/4.8

Use ____ to assess respiratory compensation in an acidosis:

Winter's formula (pCO2 = [(1.5 x Bicarbonate) + 8] +/- 2)

Learning Objectives:

a. Define metabolic acidosis b. Differential diagnosis c. Interpretation of acidosis, anion gap, compensation d. Recognizing multiple acid base disorders e. Cases

If Delta Delta is >1, metabolic _____ also present

alkalosis

The *Methanol *found in cleaning solutions, antifreeze, specialized automobile fuels can cause this permanent side effect:

blindness

Anion gap is the unmeasured anions like protein, phosphate, citrate, sulfate ____ - (___ + ___)

cations (Na+) anion (Cl- + HCO3-)

If Winter's formula is LESS than expected, then respiratory acidosis is also present. Would your patient most likely being hyper or hypoventilating?

hyperventilating (respiratory alkalosis)

If Winter's formula is HIGHER than expected, then respiratory acidosis is also present. Would your patient most likely being hyper or hypoventilating?

hypoventilating (lots of H+, breathe less)

Increased acid generation Decreased acid excretion Lack of bicarbonate production causes:

metabolic acidosis

Would saline cause a gapped or non-gapped acidosis?

non-gapped (H in hardup for hyperchloremia)

If Delta Delta <1, a ______ also present

non-gapped acidosis

Case 2: 76 year old female comes in from the nursing home after vomiting and becoming short of breath. Triage vitals: BP 80/40, HR 110, RR 24, T 102. Has a fever and RLL infiltrate on chest x-ray. Labs: Na+ 134, Cl- 100, HCO3- 18, K+ 4.8, Glc 90, ABG: 7.25/48/65/18. What are the acid base disturbances? What is causing them?

pneumonia and aspiration caused by metabolic acidosis. Major systemic inflammatory response, sepsis, Lactic Acidosis (doesn't perfuse well, increase in Lactate) Gapped b/c 134 - (100+18) = 16 Winter's Formula: 1.5(18) + 8 +/- 2 = 35 high so respiratory acidosis

Case 3: 40 y/o WM with only PMHx of depression is found unconscious at home by his brother and brought to the ER by EMS. On arrival, he is intubated for airway protection and blood work is drawn. Na+ 145, Cl- 103, HCO3- 12, K+ 5.8, Glc 78, BUN 90, Cr 6.5 ABG: 7.1/40/70 What are the acid base disturbances? What other lab would you order?

probably alcohol intox = gapped metabolic acidosis AG = 145 - (103 + 12) = 145 - 125 = 20 high = metabolic acidosis low ABG Winter's formula = 3/2(12) + 8 +/-2 = 24 to 28 since bicarb = 12 we have a respiratory acidosis Delta Delta = (20 - 8 / 24 - 12) = 12/12 = 1 An *Osmolar Gap* greater than 15 would confirm alcohol poisoning. = 326

What does delta/delta measure?

Δ anion gap/Δ bicarbonate (to look for additional disturbace)