63-year-old woman brought to an ED after being found in a stairwell on Monday morning, last seen Friday afternoon

Educational Objective:

Name iatrogenic causes of pH drop during resuscitation from shock.

Key Point:

A possible iatrogenic cause for this new metabolic acidosis is the administration of normal saline. The point of this question is two-fold: (1) In the rush to perform resuscitation, it is not uncommon for healthcare professionals to forget to monitor the ongoing volume of fluid resuscitation, especially in transfer patients. This patient accidentally received 7 L of fluid before a nurse asked how many liters had been hung, and (2) using large amounts of normal saline can cause hyperchloremic metabolic acidosis.

Explanation:

This is a true case, and the reason for the metabolic acidosis was initially puzzling to the receiving facility.

Although the creatine kinase level was elevated, it seemed too small an elevation to create this much of a shift in pH. In addition, the potassium level was not critically elevated, also indicating that something other than rhabdomyolysis was occurring.

Desaturation during transfer to the table for CT imaging would not usually be of sufficient duration to cause acidosis, and, even if it did, respiratory acidosis--not metabolic acidosis--would be expected.

Reference:

Nicks BA, Gaillard JP. "Approach to Nontraumatic Shock." (Chapter 12) Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 9e Eds. Judith E. Tintinalli, et al. McGraw-Hill, 2020, https://accessemergencymedicine.mhmedical.com/content.aspx?bookid=2353&sectionid=218079826

Evans, L., Rhodes, A., Alhazzani, W. et al. Surviving sepsis campaign: international guidelines for management of sepsis and septic shock 2021. Intensive Care Med 47, 1181–1247 (2021). https://doi.org/10.1007/s00134-021-06506-y