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22 Cards in this Set
- Front
- Back
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When should I suspect an acid-base disorder
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Unexplained dyspnea
Marked changes in fluid/volume status Abnormal HCO3 Increased anion gap |
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pH
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measure of acid concentration
Normal is 7.40 |
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PCO2
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partial pressure of CO2
measures how a patient is ventilating higher level indicates hypoventilation |
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PO2
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partial pressure of oxygen
measure of oxygenation only |
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HCO3
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bicarb concentration
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O2 sat
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oxygen saturation
determines acuity and severity of hypoxemia |
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Total CO2
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amount of CO2 dissolved in plasma
little reason to use it |
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Base excess
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amount of acid (hydrogen ions) that would be necessary to return pH to normal if the PCO2 were normal
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Base excess < - 3
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metabolic acidosis
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Base excess > + 3
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metabolic alkalosis
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Five Rules for Clinical Acid-Base Physiology
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1. Check pH
2. Process respiratory or metabolic acidosis/alkalosis 3. Calculate anion gap 4. Check for degree of compensation 5. Check for 1:1 relationship of acid and base |
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Anion Gap
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Na+ - (Cl- + HCO3-)
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Anion gap > 10
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may be a metabolic acidosis
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Anion gap > 20
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always a metabolic acidosis
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Metabolic acidosis
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1. change in PCO2 = 1.3 x change in HCO3
2. PCO2 = 1.5*HCO3 +8 (+/- 2) 3. PCO2 = last 2 digits pH |
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Metabolic alkalosis
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1. Change in PCO2 = (0.5 - 0.7)*HCO3
2. PCO2 = 0.9*(HCO3) + 9 |
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Acute respiratory acidosis
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10 mm increase PCO2 = increase HCO3 by 1
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Chronic respiratory acidosis
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10 mm increase = increase HCO3 by 3-5
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Acute respiratory alkalosis
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10 mm decrease PCO2 = decrease HCO3 by 2
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Chronic respiratory alkalosis
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10 mm decrease PCO2 = decrease HCO3 by 5
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1:1 relationship of acid and base w/ normal anion gap acidosis
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1 meq decrease HCO3 - 1 meq increase Cl-
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1:1 relationship of acid and base w/ increased anion gap acidosis
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1 point increase anion gap - 1 meq decrease HCO3
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