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Flashcards in Acid-Base Disorders Deck (20)
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Metabolic acidosis- Laboratory Findings

ctCO2 decreased
pCO2 normal
pH decreased


Compensated Metabolic acidosis- Laboratory findings

Primarily respiratory methods (hyperventilation) to lower the pCO2
ctCO2 decreased
pCO2 decreased
pH normal


Metabolic alkalosis- laboratory findings

Primary HCO3 excess seen in NaHCO3 infusion, citrate through blood transfusions, antacids, vomiting, K+ depletion, Diuretic therapy, Cushing's syndrome
ctCO2 increased
pCO2 normal
pH increased


Compensated Metabolic alkalosis- laboratory findings

Primarily respiratory (hypoventilation) increasing CO2 retention
ctCO2 increased
pCO2 increased
pH normal


Respiratory acidosis- laboratory findings

Primary CO2 acidosis from emphysema, pneumonia, rebreathing air
ctCO2 normal
pCO2 increased
pH decreased


Compensated respiratory acidosis- laboratory findings

Mainly renal by increasing H+ excretion and HCO3 reabsorption
ctCO2 increased
pCO2 increased
pH normal


Respiratory alkalosis- laboratory findings

Primary CO2 deficit seen in hyperventilation and early salicylate poisoning
ctCO2 normal
pCO2 decreased
pH increased


Metabolic acid-base disorders involve ?

Bicarbonate concentration


Compensated respiratory alkalosis- laboratory findings

Mainly renal by decreasing H+ excretion
ctCO2 decreased
pCO2 decreased
pH normal


Respiratory acid-base disorders involve ?

Carbon Dioxide concentration


Increased pCO2 causes what?

And increase in dissolved Carbon Dioxide which forms Carbonic Acid in blood, decreasing pH


Henderson-Hasselbalch Equation

Ionization constant of a weak acid
pH = pKa + log [HCO3]/[H2CO3]
Normally should be around 20/1 ratio
pH is proportional to log [HCO3]/[pCO2] ie kidney/lungs or metabolic/respiratory


Specimen Collection

Anticoagulant needs to be heparin, using anaerobic collection for blood gas/pH studies
If the blood is exposed to air, CO2 and pCO2 will go down, pH and pO2 will go up
If tested after 15 min, it needs to be iced to prevent glycolysis which will cause CO2 and pCO2 will go up, pH and pO2 will go down


Evaluating Acid-Base Disorders

Compare CO2 and HCO3, if pCO2 is going opposite pH think respiratory, if it's going with pH think metabolic


Primary Respiratory Disfunction

Change in pCO2 compensated by metabolic HCO3


Primary Metabolic Disfunction

Change in HCO3 compensated by respiratory pCO2


Main Buffer Systems

Bicarbonate-Carbonic Acid: minimize pH change in plasma and erythrocytes
Protein Buffer System: plasma proteins minimize pH change in blood
Phosphate Buffer System: minimize pH change in plasma and erythrocytes
Hemoglobin Buffer System: Hgb minimize pH change in blood, most important intracellular buffer


Metabolic Acid-Base Disorders involve

Bicarbonate concentration


Respiratory Acid-Base Disorders involve

Dissolved Carbon Dioxide concentration


Oxygen Metabolism

Transported in dissolved state, controlled by pO2, oxygen diffusion through alveoli, and hemoglobin affinity for oxygen
Release depends on H+ content of tissues and pCO2 concentration
Normal Hgb saturation is around 95%