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54 Cards in this Set
- Front
- Back
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Normal pH
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7.35-7.45
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PCO2
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35-45 mmHg
40mmHg |
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PO2
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95-100mm Hg
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HCO3
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22-26mEq/L
24mEq/L |
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SaO2
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> or = 95%
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Adverse CV consequences of acidemia
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dec. cardiac output
impairment of contractility arrhythmias inc. pulmonary vascular resistance |
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Adverse metabolic consequences of acidemia
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insulin resistance
inhibition of anaerobic glycolysis hyperkalemia |
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Adverse CNS consequences of acidemia
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coma
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other adverse consequences of acidemia
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hyperventilation- try to rid pCO2
dyspnea |
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Adverse CV consequences of alkalemia
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dec. coronary blood flow
angina, possible MI arrhythmias |
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adverse metabolic consequences of alkalemia
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hypocalcemia
hypomagnesemia hypokalemia stimulation of anaerobic glycolysis |
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adverse CNS consequences of alkalemia
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dec cerebral blood flow (lethargy, delirium, stupor)
seizures |
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other adverse consequences of alkalemia
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hypoventilation
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acid generation per day
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1mEq/kg/day
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How is acid regulated?
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buffering
renal regulation respiratory regulation hepatic regulation |
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Bicarb buffer
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rapid onset
intermediate capacity for extracellular acidosis |
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Phosphates buffer
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intermediate onset
intermediate capacity for intracellular and extracellular acidosis |
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Protein buffer
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rapid onset
limited capacity for intracellular acidosis |
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Kidneys role in acid regulation
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HCO3- reabsorbed in the proximal tubule
HCO3- generated in the distal tubule (ammonium excretion> titratable acidity) |
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Ventilatory regulation of acid
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chemoreceptors detect PCO2 and adjust respiration (inc PCO2, inc rate and depth of respiration)
rapid onset and large capacity |
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Hepatic regulation of acid
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oxidation of proteins generate HCO3 and NH4 (urea cycle)- eliminated by kidneys (dec. elim-> alkalosis)
if liver dec. NH4, bicarb will build up and cause metabolic acidosis |
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Metabolic acidosis
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dec. HCO3
compensate by dec. PCO2 (inc. respiration)- very quick |
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Metabolic alkalosis
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inc. HCO3
compensate by inc. PCO2 (dec. respiration)- very quick |
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Respiratory acidosis
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inc. PCO2
compensate by inc. HCO3 (36-72 hours) |
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Respiratory alkalosis
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dec. PCO2
compensate by dec. HCO3 (36-72 hours) |
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Full compensation in metabolic acidosis
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PCO2 should fall by 1-1.5x HCO3
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Anion gap
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Na - (Cl + HCO3)
Normal= 3-11mEq/L |
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Non-anion gap/ Hyperchloremic acidosis causes
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loss of HCO3-; replaced by Cl-
TPN (give too much Cl) fistulas, diarrhea, biliary drainage (don't reabsorb HCO3) type II renal tubular acidosis (proximal tubule heavy metal toxicity, carbonic anhydrase inhibitors) reduced renal H+ secretion/ HCO3 generation (Type I RTA/ hypokalemia RTA; Type IV RTA/ hypoaldosteronism, hyperkalemia; chronic renal failure) |
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Anion gap acidosis
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MULEPAK
methanol intoxication uremia (renal failure) lactic acidosis ethylene glycol paraldehyde ingestion aspirin ketoacidosis |
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Causes of lactic acidosis
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shock
drugs/toxins seizures leukemia hepatic/ renal failure metformin |
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symptoms of lactic acidosis
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Kussmaul respirations
peripheral vasodilation (flushing, tachycardia) hyperkalemia lethargy/coma N/V bone demineralization if chronic |
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Bicarbonate therapy
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use if pH <7.2
Dose=0.5L/kg x IBW s (desired HCO3-actual HCO3) desired HCO3= 12mEq/L give 1/3 to 1/2 calculated dose Give K+ supplements if needed |
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Bicarb therapy in cardiac arrest
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1mEq/kg
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Hazards of overalkalization
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dec. cerebral blood flow
impaired O2 relesase from Hgb CSF acidosis hypokalemia dec. ionized calcium |
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Chronic bicarbonate therapy
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for chronic metabolic acidosis
1-3mEq/kg/day |
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Causes of metabolic alkalosis
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loss of acid through GI or urine
admin of HCO3 or citrate contraction alkalosis Cl and water depletion |
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Saline responsive alkalosis causes
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Cl < 10-20mEq/L
cause: diuretic therapy vomiting and NG suctioning admin HCO3 or blood transfusions |
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Saline resistant alkalosis
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Cl > 20mEq/ml
Causes: inc. mineralocorticoid activity hypokalemia renal tubular Cl wasting |
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symptoms of alkalosis
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muscle cramps
paresthesias weakness postural dizziness cellular hypoxia, mental confusion, coma, sz myocardial suppression, CV collapse, arrhythmias, risk of MI |
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Treatment of saline responsive alkalosis
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1L NS + 20-40mEq/L KCl over 4-6 hours, then NS + 20-40mEq/L KCl at 125-200ml/hr
Monitor: I/O, BP, HR, lung sounds, electrolytes, edema OR Acetazolamide 250-500mg IVP monitor for K+ wasting AND H2 blocker or PPI if vomiting or NG suction |
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Treatment of saline resistant alkalosis
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correct hypokalemia
dec. dose of mineralocorticoid admin spironolactone (mineralocorticoid receptor antag) correct hyperaldosteronism-give fluids |
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Causes of respiratory acidosis
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failure of excretion of PCO2
airway obstruction reduced stimulus from CNS failure of heart or lungs neuromuscular defects mechanical ventilation too slow |
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symptoms of respiratory acidosis
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dyspnea, SOB
HA drowsiness, confusion, coma, sz tachycardia, arrhythmias, hypotension |
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Treatment of respiratory acidosis
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mechanical ventilation/ O2
(careful in COPD pt) use bicarb if pH<7.2 Doxapram in peds |
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Causes of respiratory alkalosis
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central stimulation of respiration (pain, fever, anxiety)
peripheral stimulation of respiration mechanical ventilation too fast pulmonary edema, pneumonia salicylate intoxication |
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Symptoms of respiratory alkalosis
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lightheadedness, confusion, sz
dec. cerebral blood flow tetany, muscle cramps N/V |
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Treatment of respiratory alkalosis
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ventilation, sedation, paralysis
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Treatment of saline resistant alkalosis
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correct hypokalemia
dec. dose of mineralocorticoid admin spironolactone (mineralocorticoid receptor antag) correct hyperaldosteronism-give fluids |
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Causes of respiratory acidosis
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failure of excretion of PCO2
airway obstruction reduced stimulus from CNS failure of heart or lungs neuromuscular defects mechanical ventilation too slow |
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symptoms of respiratory acidosis
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dyspnea, SOB
HA drowsiness, confusion, coma, sz tachycardia, arrhythmias, hypotension |
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Treatment of respiratory acidosis
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mechanical ventilation/ O2
(careful in COPD pt) use bicarb if pH<7.2 Doxapram in peds |
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Causes of respiratory alkalosis
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central stimulation of respiration (pain, fever, anxiety)
peripheral stimulation of respiration mechanical ventilation too fast pulmonary edema, pneumonia salicylate intoxication |
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Symptoms of respiratory alkalosis
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lightheadedness, confusion, sz
dec. cerebral blood flow tetany, muscle cramps N/V |
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Treatment of respiratory alkalosis
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ventilation, sedation, paralysis
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