Acid/Base Disorders

Acid/Base Disorders

1. norm pH= 7.38-7.42

   • pH< 7.35 = acidemia
     • pH>7.45 = alkalemia

2. Resp Acidosis

   • incr. PCO2 (hypercapnia)
     • decr. pH
       • failure of lungs to eliminate CO2
         • COPD, pneumonia, neuromuscular disease
   • clinically
     • metabolic (hypercapneic) encephalopathy
     • renal compensation takes days
   • Rx =Rx underlying disorder
   • lab
     • rise in serum HCO3

3. Resp Alkalosis

   • decr. PCO2
     • incr pH
   • disorders that cause incr. resp drive, excess CO2 elimination
   • causes
     • PE, sepsis,, anxiety (hypervent), salicylate tox, hypoxia, primary CNS dis., pregnancy
   • clinically
     • obvious hyperventilation
     • tetany-like syndrome
       • may look like hypoCa++
     • parasthesias in ext, chest discomfort, light-headed
     • *circumoral paresethesias
   • decr. CO2 leads to renal excr. of HCO3 (slow)
   • Rx underlying disorder

4. Metabolic Acidosis

   • decr. serum HCO3
     • incr. H+
   • Anion gap acidosis
     • early hyperventilation
     • lethargy to coma
   • Non anion gap acidosis
     • loss of HCO3
       • ie. severe diarrhea
       • renal losses (tubular acidosis)
     • no change in anion gap
     • usually hyperchloremic (high Cl)
       • Cl incrs. as HCO3 drops
       • poop out HCO3, kidneys noticed and soak up Cl to make neutral charge
   • acute acidosis
     • resp. response is immediate
   • Labs
     • decr. HCO3 & pH
     • serum electrolytes, ABG, seerum albumin

5. Na-(HCO3 + Cl) ~12

6. Metabolic Alkalosis

   • incr. serum HCO3 & incr. pH
   • no acute change in PCO2
   • vommiting
     • loose H+ & Cl
   • addition of HCO3 (intake)
   • Diarrhea
     • diproportion loss of Cl
   • Diuresis
     • loss of chloride
   • causes
     • nasogastric suctioning
       • villous adenoma
         • tumor in bowel secretes NaCl
         • hypercalcemia
           • Milk-alkali syndrome
             • ingest lg amt. Ca++ & absorbable alkali
             • Gitelman's syndrome
   • clinical
     • neuro symp
     • paresthesias, carpopedal spasm
       • low ionized Ca++
     • symp of vol depletion
   • Rx
     • incr. renal excretion of HCO3
       • give HCO3
     • Cl responsive
       • give NaCl
     • Cl-unresponsive
       • mineralocorticoid excess
         • aldosterone antagonist
         • Cushing's

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