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  #1  
Old 01-18-2012
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Lungs Respiratory Alkalosis with Low Bicarb?

A 40-year-old woman is admitted to the intensive care unit with hypotension and shortness of breath. Arterial blood gases reveal a PaCO2 of 10 mm Hg and a bicarbonate concentration of 12 mEq/L. These findings are indicative of which of the following acid-base states?

A. Normal
B. Respiratory acidosis
C. Metabolic acidosis
D. Respiratory alkalosis
E. Metabolic alkalosis
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Old 01-18-2012
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c. Met. Acidosis w respiratory compensation
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Old 01-18-2012
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Ans C........
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Its D. Resp alkalosis
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D resp alkalosis
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Old 01-18-2012
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I guess its PE with resp alkalosis :s
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Old 01-19-2012
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why is it resp alkalosis ?? even in a acute condition like PE causing resp alkalosis , hco3 would not be 12 as renal compensation takes 3 days ...

whats the ans ?????
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Old 01-19-2012
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Ans seems D

but i hope this Qs make sense after OP post the soln coz .how the patient with shortness of breath hyperventilate .and if we think of metabolic acidosis with the patient hyperventilating and blowing off co2 also make sense

@hitman totally agreed ,how can an acute condition (PE) present with metabolic acidosis ??
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Old 01-19-2012
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EXPLANATION: The arterial pH can be calculated using the Henderson-Hasselbalch equation.
pH = 6.1 + log [HCO3]/(PaCO2x 0.03 mmol/L/mm Hg)
pH = 6.1 + log 12 mmol/L/(10 mm Hg x 0.03 mmol/L/mm Hg)
pH = 6.1 + log 40 = 6.1 + 1.6 = 7.7
The patient has an alkalemia due to hyperventilation and therefore is suffering from a respiratory alkalosis. In an acute respiratory alkalosis, the bicarbonate typically decreases by 2 mM for each 10 mm Hg decrease in PaCO2; in a chronic respiratory alkalosis, the bicarbonate typically decreases 4 mM for each 10 mm Hg decrease in PaCO2. In this case, the PaCO2 has decreased by 30 mm Hg. Because bicarbonate has decreased by 12 mM, the diagnosis is consistent with a chronic respiratory alkalosis.

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Makes sense...
Where have you found this question?
Seems to be a bit unfair
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ok ...... but did not feel we going to get these type of qs unless they provide us log tables , secondly as far as i know compensation is never complete and so it cannot be that you lose 30 mmhg of co2 and thus lose 12 mm ... apart from that nice qs i never thought solving this equation ....
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