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16 Cards in this Set
- Front
- Back
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While monitoring the arterial blood-gas values for a 78 year-old woman on a mechanical ventilator and oxygen in the ICU, the attending physician observes the following arterial blood gas values and electrolytes. [HCO3-] = 17 mM, pCO2= 22 mm Hg, [Na+] = 132 mM, [Cl-] = 103 mM. What is the best diagnosis?
1.Acute respiratory acidosis 2.Chronic respiratory acidosis 3.Acute respiratory alkalosis 4.Chronic respiratory alkalosis 5.Metabolic acidosis 6.Metabolic alkalosis 7.No blood-gas problems 8.Problem with laboratory results |
4. Chronic respiratory alkalosis
*why respiratory and not metabolic alkalosis? Because both pCO2 and HCO3 are decreased, decreased pCO2 produces alkalosis, decreased HCO3 causes acidosis. |
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A 56 year-old male smoker suffering from emphysema is admitted to the emergency department with labored breathing.The reported blood-gas values and electrolytes are [HCO3-] = 32 mM, pCO2= 65 mm Hg, [Na+] = 140 mM, and [Cl-] = 102 mM. What is the diagnosis?
1.Acute respiratory acidosis 2.Chronic respiratory acidosis 3.Acute respiratory alkalosis 4.Chronic respiratory alkalosis 5.Metabolic acidosis 6.Metabolic alkalosis 7.No blood-gas problems 8.Problem with laboratory results |
1. acute respiratory acidosis
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How does the body compensate for respiratory defects in pCO2 that cause hyperventilation?
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Hyperventilation -> Dec. pCO2 -> alkalosis -> Kidney's compensate by excreting bicarbonate
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How does the body compensate for respiratory defects in pCO2 that cause impaired lung function?
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impaired lung function -> Inc. pCO2 -> acidosis -> Kidney's compensate by retaining [HCO3-] and by excreting acid
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How does excretion of a non-volatile buffer such as phosphate enable better buffering?
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The ability to excrete acid is limited to approximately 1000 fold (3pH units). Excretion of non-volatile buffers such as phosphate enable secretion of more acid.
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How do the kidney's synthesize more HCO3 to compensate for acidosis?
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glutamine to glutarate to alpha-keto-glutarate :-)
each reaction yields a ammonia molecule, which diffuses across the membrane to the lumen of the nephron and is protonated to ammonium and excreted. alpha ketoglutarate is converted to bicarb, and pumped into the blood, using a sodium symporter. |
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A 3 year-old girl is brought to the ED in a stupor with rapid breathing. The parents indicate that the child was normal other than frequent diarrhea during the last 24 hours. The arterial blood-gas values are [HCO3-] = 14 mM, pCO2= 29 mm Hg, [Na+] = 130 mM, [Cl-] = 103 mM. Which of the following is the most likely diagnosis?
1.Acute respiratory acidosis 2.Chronic respiratory acidosis 3.Acute respiratory alkalosis 4.Chronic respiratory alkalosis 5.Metabolic acidosis 6.Metabolic alkalosis 7.No blood-gas problems 8.Problem with laboratory results |
5. metabolic acidosis
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What can cause metabolic acidosis?
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Increased acid production (lactate or ketoacids), loss of bicarb. (diarrhea), or accumulation of endogenous acids (renal failure)
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A 16-year old female is brought to the ED by her parents. The patient is mentally confused suffering muscle cramps and frequent vomiting. Her arterial blood gas values are [HCO3-] = 34 mM, pCO2= 45 mm Hg, [Na+] = 140 mM, [Cl-] = 91 mM. Which diagnosis is most likely?
1.Acute respiratory acidosis 2.Chronic respiratory acidosis 3.Acute respiratory alkalosis 4.Chronic respiratory alkalosis 5.Metabolic acidosis 6.Metabolic alkalosis 7.No blood-gas problems 8.Problem with laboratory results |
6. metabolic alkalosis
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What are common causes of metabolic alkalosis?
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1. Loss of non-volatile acid (vomiting).
2. failure of kidneys to excrete bicarb. (diuretics) |
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How do you calculate the anion gap?
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anion gap = [Na] - ( [Cl-] + [HCO3-] )
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What is a normal serum sodium value?
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136-145 mM
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What is a normal serum chloride value?
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95-105 mM
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What is a normal anion gap?
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12 +/- 3 mM
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What does a high serum anion gap mean?
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acidosis
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What does the kidney synthesize and secrete to increase bicarbonate levels?
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Ammonium (acid)
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