Metabolic Acidosis

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Metabolic Acidosis

• Alex Flaxman, MD, MSE

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Presentation

• 50 yo M, 4d h/o vomiting R inf chest/RUQ pn
• Wife adds 10-15 lb wt loss x4d and lethargic,
  sleeping 23 hrs/day
• Vomiting
• After eating, but also when doesnt eat, NBNB.
  Has been able to tolerate Gatorade, and has
  increased his intake of Gatorade.
• Pain
• R-sided, underneath ribs, occ rad to L

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Priors

• Pt in ED ? MICU 8/04 for same
• S/p CTAP, UGI LGI endoscopy
• Investigated for toxidrome
• Denies EtOH, home-made alcohol, antifreeze,
  ethylene glycol, MeOH, pica, or other tox
  exposures. DOH visit to home.
• EGD 6 wks ago for N/V, neg as per pt
• Travel 3 wks ago to Palm Beach, FL

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ROS

• General -chills, fatigue
• CV CP
• Resp SOB, Cough
• GI N/V, abd pn, -diarrhea, -blood
• GU -freq/hematuria/urgency

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• All NKDA
• PMH Depression x2yrs, hyperchol, disc
• herniations L3, L4, L5 s/p bk inj
• PSH Laminectomy x2, UGI, LGI,
• EGD 6 wks ago
• Meds Compazine x1d, Nexium, Zoloft,
• Vicodin, Somma
• PMD _at_BI

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• Tobacco 1 ppd, h/o 2-3 ppd
• EtOH Denies
• Drugs Denies

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Vital Signs

• BP 161/103
• P 129
• R 24
• O2 97
• T 99.4 PR
• Pn 10/10

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Exam

• General WDWN, NAD, tachypneic
• Pul CTAB
• CV Tachy, reg, S1, S2, -m/r/g
• Abd NABS, RUQ tend, epig tend, masses-
• liver edge 9 cm inf to costal margin
• Rectal Guaiac neg w/ no stool
• Ext -edema, hyperpig L foot cool
• R PT 2 DP Doppler
• L PT Doppler DP Doppler

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• EKG
• SR _at_ 124 w/ LAE
• ? Q II, aVF (new from 8/31/04)
• ? ST elev V2, V3
• Sinus tach new from 8/21/04
• CXR
• NAD, -free air
• NG Lavage
• Yellow-green material, no blood

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What labs do you want?
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Labs
Lipase 159Troponin 0.02
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More Labs
UACloudyProt 100WBC 0-5RBC 0-3Hyaline Casts
0-5
AST 74ALT 6Alk 163TB 3.6DB 0Alb 5.2TP 9.7
Lactate 2.2 Acetone neg EtOH 0 Serum osmolarity
290
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Now What?
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ABG
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Rule 1 Acidosis or Alkalosis

• Acidosis

7.12 / 18 / 105 / RA / 8.3
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Rule 2 Metabolic, Respiratory, Both

• Metabolic

7.12 / 18 / 105 / RA / 8.3
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Rule 3 Anion Gap
7.12 / 18 / 105 / RA / 8.3

• AG ?

Na Cl HCO3
136 112 6 18

• So we have an
• Anion Gap Metabolic Acidosis

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Rule 4 Degree of Compensation

• For metabolic acidosis,
• Expected PCO2 1.5(HCO3) 8 2

1.5(6) 8 2 9 8 2 17 2
15, 19
7.12 / 18 / 105 / RA / 8.3
Actual PCO2 is 18 ? appropriate compensation
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Rule 5 d/d
7.12 / 18 / 105 / RA / 8.3

• Any takers?

AG 18 (nl 6.6-10.6) HCO3 6 (nl 24)
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Rule 5 d/d

• AG should be 10 but is now 18, for a difference
  of 8
• The AG went up by 8, so the HCO3 should go down
  by 8.
• So HCO3 should be 24 8 16 but is really 6.

The HCO3 is lower than predicted so there is also
a concurrent non-AG metabolic acidosis.
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Causes of AG Metabolic AcidosisMUD PILES

• Methanol wood alcohol, grain alcohol
  (moonshine), paint thinners, windshield washer
  fluid
• Uremia
• DKA, AKA

• Paraldehyde, propylene glycol
• Ingestions (INH, iron, XTC, cocaine)
• Lactic Acidosis
• EtOH, Ethylene glycol
• Salicylates

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Other causes

• P Phenformin
• Toluene poisoning (glue sniffing)
• Other organic acids
• Lactic acid
• Acetone
• Ketoacids hydroxybutyrate / acetoacetate
• Hippuric Acid
• 5-oxyproline
• Salicylates

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Lactic Acidosis

• Usually increase in the L isomer
• Type A
• 2 to hypoxia (hypoperfusion, sepsis)
• Type B
• Not d.t. hypoxia seizures, liver failure,
  thiamine deficiency
• D-Lactic Acidosis- increase in the D isomer

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D-Lactate
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D-Lactate External Sources

• Ingestion of fermented fruits and vegetables
  pickles, yogurt, sauerkraut
• LR and dialysate contain dl-lactate (50/50)
• Propylene glycol ?metabolism?

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D-Lactate Internal Sources

• In the gut, glucose is metabolized by flora to
  lactate
• l-Lactate
• d-Lactate
• Produced via the methyl-glyoxal pathway (part of
  threonine catabolism)
• (threonine is an essential amino acid)

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D-Lactate Internal Sources

• Pyruvate ? dl-Lactate via Lactate Dehydrogenase
• BUT

Pyruvate ? l-Lactate requires l-LDH Pyruvate ?
d-Lactate requires d-LDH Mammals do not have d-LDH
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D-Lactate Getting rid of it

• Slowly metabolized? Not.
• d-hydroxy-acid-dehydrogenase
• Mitochondrial enzyme
• In many tissues (especially liver and kidney)
• Converts d-lactate (and other substrates) to
  pyruvate
• But overall, d-lactate is metabolized more slowly
  than l-lactate

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D-Lactic Acidosis

• An increase in D-Lactate (duh)

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Symptoms

• Tachypnea

• AMS
• Slurred speech
• Confusion
• Inability to concentrate
• Somnolence
• Hallucinations
• Clumsiness

• Weakness
• Ataxia / unsteady gait
• Nystagmus
• Irritable
• Abusive behavior
• Ptosis
• Asterixis

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Risk Factor

• Anything that results in increased delivery of
  undigested carbohydrates to the colon

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Risk Factors

• Short Bowel Syndrome
• 1 Surgical resection
• 2 Intestinal bypass (bariatric surgery)
• Feeding tube placement
• Intestinal malabsorption?
• Chronic pancreatitis

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Risk Factors Not from the HP

• Alteration of normal colon flora to a
  predominance of Gm anaerobes (lactobacillus)
• ? Colonic stagnation
• Impaired metabolism

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Precipitating Factors

• Excessive oral food intake
• Especially carbohydrates (like Gatorade)
• Change in enteral feeding formula

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Labs

• Renal function normal or abnormal
• AG Metabolic acidosis
• Can have non-AG metabolic acidosis
• Elevated serum or urine D-lactate
• Serum level gt 3 mmol/L

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Ancillary Tests

• LP CSF D-lactate levels same as serum
• EEG b/l diffuse, high-voltage slow waves
  without focal abnormality
• Stool culture predominance of Gm anaerobic
  organisms
• Lactobacillus
• Bifidobacterium
• Eubacterium

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Immediate Treatment

• A-B-C
• NPO
• IV dextrose (e.g. D5NS)

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Treatment

• Supportive
• Adjust feeding tube
• Adjust enteral feeding formula
• Change diet to starch instead of carbohydrates ?
  recurrent attacks
• Surgical reanastomosis
• Oral abx neomycin, vanco, kanamycin, metro
• Bicarb- unclear

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Treatment

• Increase luminal pH
• CaCO3, MgCl2
• HCO3
• Abx
• Oral vanco, metro, or neomycin
• Although can cause overgrowth of lactobacillus
• Dialysis
• Corrects acidosis
• Clears d-Lactate

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Other Interesting Points

• d-Lactate levels correlate poorly with symptoms
• Normal humans infused with d-lactate do not
  develop symptoms
• Other acidoses to the same pH do not cause
  similar symptoms

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Final dorky Interesting Point
7.12 / 18 / 105 / RA / 8.3

• AG metabolic acidosis and concurrent non-AG
  metabolic acidosis
• Why?

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Final dorky Interesting Point

• In D-lactate acidosis the increase in the AG
  tends to be less than the decrease in the HCO3.
• In L-lactic acidosis where the increase in the AG
  tends to be greater than the reduction in the
  bicarb.

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Final dorky Interesting Point

1. Much lower renal threshold for d-lactate than for
   l-lactate
2. Loss of the sodium salt of D-lactic acid in the
   stool (the H is resorbed from the lumen or
   reacts with secreted HCO3) but the organic ion
   does not

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Take Home Points- General

1. Consider ABGs more often
2. Look for causes of metabolic acidosis
3. In unclear cases, or cases where MUD PILES fails,
   send tests for organic acids (e.g. d-lactate and
   ß-hydroxybutyrate)
4. Involve intensivist early

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Take Home Points- d-Lactate

• For patients with short bowel (or other
  malabsorption risks), consider D-lactic acidosis.
• Also consider when AG acidosis and
• Nl lactate levels and no acetone
• Short bowel or other malabsorption syndrome
• Preceded by food ingestion (and symptoms improve
  after discontinuation)
• Characteristic neurological findings

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