A critical care unit nurse presents to the ED with severe dizziness. She appears

Question

A critical care unit nurse presents to the ED with severe dizziness. She appears to be a fit woman. She was not forth coming for any other history.  Her ABG and blood panel are below. Her blood work reveals hyponatremia, hypokalemia and a very high bicarbonate (which can only be due to severe metabolic alkalosis or metabolic compensation for severe respiratory acidosis (more common).

Na+ = 123                                           pH = 7.55

K+ = 3.1                                               Paco2= 50

Cl- = 67                                                Pao2 = 80

HCO3-=42                                            HCO3- = 43

Glu = 125

BUN = 25

i.Determine her acid/base balance based on the above numbers. (4 pts)

ii.Confirm her measured bicarbonate level.  Then remember that her Paco2 should go up by 0.6 for each mEq/L her bicarbonate value is over 24. Go ahead and do that math. (2 pts – show your work)

iii.Is your calculated number above or equal to her measured Paco2 or is it below that number?  If above or equal to, no compensation has occurred, whereas if below, compensation has occurred.  Has compensation occurred? (3 pts)

iv.On further examination you discover poor dentition (receding gum lines) and scratch marks on her right hand. You ask for a urine sample to be run. This test reveals trace ketones in her urine and zerochloride in her urine.  She is losing chloride via her GI tract.  Any ideas as to what might be the most likely diagnosis for this patient? (5 pts extra credit)

Explanation / Answer

Ans. i.

pH = 7.55 (normal value is 7.4)

Paco2 = 50 (normal value is 35-45)

HCO3- = 42 (normal value is 22-26)

Hence high pH, high Paco2 and high HCO3- indicates METABOLIC ALKALOSIS.

Ans. ii

Paco2 normal value is 35-45

HCO3- normal value is 22-26

It is given that, for each bicarbonate value of over 24, Paco2 value rises by 0.6 from normal, therefore,

Bicarbonate level given here is 42.

If we take baseline value of bicarbonate as 24, then,

42 - 24 = 18

For each 1 value, Paco2 go up by 0.6, therefore for,

18 values, paCO2 will go up by, 18 × 0.6 = 10.8

Normal range of Paco2 is 35-45, therefore when we add 10.8 to 35,

10.8 + 35 = 45.8

But the level given for Paco2 is 50 for HCO3- level of 42.

Hence calculated level of Paco2 is less.

Therefore the level of HCO3- is not confirmed.

Ans. iii.

Calculated number is BELOW the measured Paco2 value

Calculated value of Paco2 = 45.8

Measured value of Paco2 = 50

Since the value is below, it shows that COMPENSATION has occurred.

Ans. iv.

Receding gum lines can be because of diabetes. Traces of ketone bodies has caused pruritis due to which scratch marks are there on right hand. Overall patient is having METABOLIC ALKALOSIS along with hyponatremia, hypokalemia and even hypochloremia.

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