80 female with suspected ischemic gut…… pH 6.9, PC02 35, HCO3 8 Why is the acidemia important?
Consequences of Severe Acid Base Disorders Severe Acidemia –Negative ionotropy –Arrythmias –Reduced response to catecholamines –Hyperkalemia –Muscle weakness –Altered LOC and seizures –Poor enzyme function Severe Alkalemia –Reduced coronary blood flow –Arrythmias –Hypokalemia –Altered LOC and seizures –Poor enzyme function
Case 75 yo female Altered LOC Fever Sinus tachycardia Tachypnea ABG: pH 7.50, pC02 30, HC03 23 Interpretation? Diagnosis? Differential dx of the acid/base disorder?
Cases 70yo smoker since birth COPD exacerbation pH 7.15, pC02 60, HC03 26 –Is he a chronic CO2 retainer? pH 7.35, pC02 60, HC03 32 –Interpretation? pH 7.05, pC02 100, HC03 32 –What is his “normal” pC02?
Chronic Respiratory Acidosis You know that the HC03 increases in a 1:3 ratio to the increase in pC02 If the HC03 is up by 7, the pC02 is chronically up by about 20 What is the differential dx of respiratory acidosis?
ANION GAP What is the anion gap? What is the formula? What is a “normal” anion gap? What could cause a LOW anion gap?
ANION GAP Na+ K+ Ca++ Mg++ Cl- HCO3- P04- S04- Albumin Organic acids
Low Anion Gap Hypoalbuminemia Increased Ca, Mg, K Lithium intoxication Multiple myeloma
What is the Delta Gap? Delta Gap –Change in AG – change in HC03 –(AG – 12) – (24 – HC03) –Essentially looks for similar changes in anion and drop in bicarb as a marker for additional acid base disorders –Questionable validity
Case 55yo male, street person, found lying in snow by CPS, confused, no history, denies ingestions, no PMHx or meds Temp 33, HR 72, BP 120/60, RR 28, sats 98%, GCS 13 Exam unremarkable except shivering ABG: pH 7.26, pC02 13, HC03 5 Na 129, K 4.7, Cl 88, C02 7 What is the A/B disorder? What other labs do you want?
Case BUN 15, Cr 136 ASA –ve Lactate 1.2 CarboxyHb 0.8% EtOH –ve Toxic alcohols –ve Glucose 2 Urine ketone +ve What is the dx? What is the ddx of an increased AGMA?
Increased AGMA: AMUDPILECATO AASA MMethanol, Metformin UUremia DDKA PParaldehyde, Phenformin IIsoniazid, Iron LLactate EEthylene glycol CCO, CN AAKA, alcohol TToluene, Theophylline OOther –H2S –Any toxin that leads to lactic acidosis (essentially all severe overdoses with hypotension, seizures)
How to narrow the ddx with an increased AGMA Normal glucose rules out DKA BUN, Creatinine ASA level ABG for carboxyHb, lactate Toxic alcohol level
Which toxins cause an increased AGMA independent of lactate? Methanol Ethylene glycol ASA
10yo girl, DKA, pH is 6.9 Would you give bicarb? What is the theoretical reason to give bicarb for acidemia? What are the complications? What are indications for bicarb? Is there any evidence for or against bicarb?
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