41-year-old male with a 20 history of severe
diarrhea was admitted to the ER after fainting. History of eating “street
food” at a parade 1 day previously. Physical
exam revealed decreased skin turgor. Arterial blood gas
analysis revealed pH = 7.21; PCO2 = 26 mmHg; [HCO3-]
= 10 mEq/L; K+ = 2.2 mEq/L with a normal anion gap .
The correct diagnosis of his condition is:
A.) combined
metabolic and respiratory acidosis
B.) metabolic
acidosis secondary to hyperkalemia
C.) metabolic
acidosis with respiratory compensation
D.) respiratory
alkalosis with renal compensation
E. ) uncompensated
metabolic acidosis
_______________
The correct answer for the quiz Oct 14, 2011 is (B), i.e., pH 7.23; PCO2
31; HCO3- 12
The presentation is consistent with ketoacidosis (ketones
are volatile acids that are eliminated via both kidneys and lungs). The
overutilization of fats for metabolism leads to ketoacidosis, a metabolic
acidosis. The low pH stimulates the carotid pH receptor leading to
hyperventilation (lower PCO2), which is compensatory. Compensation is
always aimed at restoring the ratio HCO3/PCO2 back to a normal value, so if
HCO3 decreases, PCO2 must decrease via hyperventilation to provide
compensation. Choice A is a mixed acid base disorder with both metabolic and
respiratory acidosis (hyperventilation) and not consistent with the history and
the pattern of breathing. Choices C and D are both alkalosis so not consistent
with the history, presentation, etc.
A 34-year-old man with
type 1 diabetes is admitted to the emergency department after being found
unconscious and unresponsive at home. His breath has a "fruity"
odor. The EMTs indicate that his family says that his diabetes has been
"out of control" lately.
He has no other medical problems. His breathing is deep and rapid.
An arterial blood sample is taken for analysis. Which of the following
sets of arterial blood gases is most likely.
A.pH 7.02; PCO2 51; HCO3-
12
B.pH 7.23; PCO2 31; HCO3-
12
C. pH 7.55; PCO2 41; HCO3-
35
D.pH 7.52; PCO2 46; HCO3-
35
