Question

Jessica's wedding to the man of her dreams was perfect in every respect. However, while on her honeymoon in Mexico, Jessica had severe "traveler's diarrhea." Despite attempts to control diarrhea with over-the-counter medications, she continued to have 8-10 watery stools daily. She became progressively weaker, and on the third day, she was taken to the local emergency department. On physical examination, Jessica's eyes were sunken, her mucous membranes were dry, and her jugular veins were flat. She was pale, and her skin was cool and clammy. Her blood pressure was 90/60 when she was supine (lying) and 60/40 when she was upright. Her pulse rate was elevated at 120/min when she was supine. Her respirations were deep and rapid (24 breaths/min). Her laboratory tests were performed and the results are shown below.

Arterial blood
pH= 7.25 (normal, 7.4)
PCO2 = 24 mm Hg (normal, 40 mm Hg)
HCO3- = 10.2 mEq/L (normal, 24 mEq/L)
Venous blood
Na+ = 132 mEq/L (normal, 140 mEq/L)
K+ = 2.3 mEq/L (normal, 4.5 mEq/L)
Cl- = 111 mEq/L (normal, 105 mEq/L)
Jessica was admitted to the hospital, where she was treated with strong antidiarrheal medications and an infusion of NaCI and KHCO3. Within 24 hours, she felt well enough to be released from the hospital and enjoy the rest of her honeymoon.
1.What is the value of Jessica's anion gap? Is it increased, decreased, or normal? What is the significance of the anion gap in this case?
2.Why was Jessica's blood pressure lower than normal?

Answer 1

Jessica's anion gap is normal, indicating that her metabolic acidosis is not due to the accumulation of unmeasured anions. Her low blood pressure is due to severe dehydration and electrolyte imbalance from diarrhea, leading to decreased cardiac output.

Step-by-step explanation:

Understanding Jessica's Anion Gap and Low Blood Pressure

Jessica's anion gap can be calculated using the formula: Anion Gap = Na+ - (Cl- + HCO3-). From the given values, it is 132 mEq/L - (111 mEq/L + 10.2 mEq/L) which equals 10.8 mEq/L. The normal anion gap is typically between 8 and 12 mEq/L, so Jessica's anion gap is within normal range. The significance of the anion gap here is that it helps differentiate between the various causes of metabolic acidosis. A normal anion gap suggests that the cause of the acidosis is not due to the accumulation of unmeasured anions.

Jessica's blood pressure was lower than normal, a condition known as hypotension. This likely occurred because of severe dehydration and electrolyte imbalance caused by excessive fluid loss through diarrhea. The reduced intravascular volume leads to decreased cardiac output and, consequently, low blood pressure.