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21 Cards in this Set
- Front
- Back
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What is the effect of hypoventilation in terms of acidosis or alkalosis?
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Acidosis - increase in pCO2
e.g. caused by myasthenia gravis, botulism, congestive lung disease |
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What is the effect of hyperventilation in terms of acidosis or alkalosis?
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Alkalosis - decrease in pCO2
e.g. caused by stress in horses/cats |
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What types of acidosis/alkalosis would these be?
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Respiratory
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Which level of ion is changed in order to be "metabolic" acidosis/alkalosis?
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Bicarbonate
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Give an example of how metabolic alkalosis can occur
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Retention of gastric juice
Loss of gastric juice (e.g. vomiting) So bicarbonate is not neutralised in duodenum and is reabsorbed |
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Give examples of how metabolic acidosis can occur
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Loss of HCO3 from gut - diarrhoea
Excess production of non-volatile acids - ketoacidosis (e.g. diabetes mellitus), lactoacidosis (e.g. excessive intense exercise), ingesting substance that forms acid in body (antifreeze forms oxalic acid) |
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What is the anion gap?
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Gap between anions and cations:
AG= (Na + K) - (Cl + HCO3) |
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What is the anion gap in normal circumstances?
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10-20mM
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Why does an anion gap exist?
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As phosphate and sulphate are not included
(difference between pos. and neg. ions) |
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Why does an anion gap give an indication of ketosis?
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Acetoacetate effectively replaces bicarbonate, more pos. ions, bigger anion gap
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What is the normal concentration of HCO3 in the blood?
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24mM
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What is the normal pCO2 in the blood?
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40mmHg
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How does the body compensate if there is an increased concentration of HCO3 in the blood?
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Increase ratio of carbonic acid:bicarbonate
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What are primary respiratory acidosis/alkalosis problems caused by?
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Increased or decreased carbonic acid
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What are primary metabolic acidosis/alkalosis problems caused by?
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Increased or decreased bicarbonate
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How does the body compensate for a respiratory acidosis?
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Renal compensation by increasing bicarbonate
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How does the body compensate for a metabolic acidosis?
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Respiratory compensation by lungs by decreasing pCO2 -> decreases carbonic acid
increase in ventilation |
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What are 4 things to consider when measuring acid base status?
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Closed container - no gas exchange between blood and air
Prompt sample - cells will metabolise and produce lactic acid Arterial blood - reflects whole body, venous blood reflects tissue from which it comes so blood is usually lower in pH from lactic acid and CO2 Choice of anticoagulant - EDTA is acidic, use heparin |
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What will the blood gas analyser measure?
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[H] ions, and pCO2
thus bicarbonate |
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How would you detect a metabolic acidosis?
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Lowered bicarbonate without a raised pCO2 or lowered pCO2 to compensate (hyperventilation)
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WORK OUT FIRST:
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Is it an acidosis or an alkalosis?
Then look at bicarbonate to see if normal or metabolically caused Then pCO2 |
