Doctorese babble -- Acid/Base

Acid/Base

pH: 7.35-7.45
HCO3: 24-26
CO2: 35-40

ABG: pH/pCO2/pO2/HCO3/SaO2


Anion gap = 12-16. Na – (Cl+HCO3)
Increased in anion gap metabolic acidosis



Urinary anion gap

     1. Na -(Cl + K)
     2. Normal = < 0
     3. > 0, RTA

Serum osmolarity

     1. 2Na +glucose/18 +BUN/2.8

     2. Normal = 280-300

Serum Osmolar gap
     1. Elevated gap – Ethylene glycol and MeOH
     2. Elevated = > 25

Respiratory acidosis
     1. pH < 7.35
     2. PCO2 > 45
     3. Compensation is metabolic retention of bicarb

Respiratory Alkalosis – hyperventilation
     1. pH > 7.45
     2. CO2 < 35

Metabolic Acidosis -- Diarrhea
     1. pH < 7.35
     2. HCO3 decreased
     3. Nonanion gap (<12)
          a. Diarrhea – 3rd space
          b. RTA
          c. Then measure urine AG
                 i. <0 – diarrhea
                 ii. >0 – RTA
     4. Anion gap Metabolic acidosis (>12 AG)
          a. Aspirin overdose
                i. Respiratory alkalosis first, then MA
                ii. Measure LFT
                iii. tinnitus
          b. Lactic acidosis
                i. Exercise
                ii. Hypovolemia
          c. Uremia
          d. Ethylene glycol
                i. Increased osmolar gap
                ii. Calcium oxylate stones
          e. Methanol – affects retina à color blindness à blindness
          f. DKA – hyperkalemia
Serum Anion Gap


∆∆ = Serum AG – 12 + HCO3
     1. Only calculate in AG met. Acidosis
     2. If ∆∆ < 23 – non-AG met acidosis + AG metabolic acidosis
     3. If ∆∆ > 30 – metabolic alkalosis + AG met acidosis


Metabolic Alkalosis

   *Hypochloremic state
    pH Increased
    HCO3 increased

    CO2 increased – compensatory mechanism
     1. Saline responsive
            a. Contraction alkalosis
            b. HCO3 moves to ECF due to dehydration, usually from emesis
            c. Pyloric stenosis ****
                    i. Hypochloremia
                    ii. Hyponatremia
                    iii. Metabolic alkalosis
     2. Non-saline responsive
            a. Hyperaldosteronism
                    i. Primary
                    ii. Secondary
            b. Bartter’s Syndrome
                    i. Inherited thick ascending limb defect
                    ii. Low K
                    iii. Alkalosis
                    iv. Normal to low BP
                    v. Seen 24-30 weeks gestation with polyhydramnios
                    vi. Polyuria and polydipsia postnatal
                    vii. Hypercalciuria and nephrocalcinosis
                    viii. Presentation
                           1. Chronic vomiting
                           2. Diuretic abuse
                           3. Mg deficiency
                           4. Often have elevated rennin and aldosterone
            c. Gitelman syndrome
                    i. AR kidney disorder
                    ii. Metabolic alkalosis
                    iii. Hypocalciuria
                    iv. Hypomagnesemia
                    v. LoF of thiazide-sensitive Na-Cl symporter in distal convoluted tubule
            d. ***Hypokalemia