Purpose
Acid-base physiology can be challenging for students to understand, in particular its usefulness in the assessment and management of patients. We have created a manikin-based simulated patient case for first-year medical students that illustrates the application of calculating an anion and osmolar gap to develop and refine a differential diagnosis for a patient with altered mental status.

Methods
The simulation curriculum at the AU/UGA Medical Partnership (MP) is integrated with large-group lectures and small-group learning during the first two years. Cases are created for topics that have been determined by faculty to be challenging for students and would benefit from a second pass as a hands-on learning exercise. After reviewing available open-access simulation cases online, it was determined that none existed focused on acid-base physiology for first-year medical students. The case was written and reviewed by MP clinical and basic science faculty and piloted with upper-level medical students prior to implementation. Students have two large group didactic lectures on acid-base physiology in the months prior to participating in the simulated encounter. Student feedback in the form of an anonymous survey is solicited after every simulation encounter for purposes of performance improvement and for faculty assessment.

Results
40 of 60 students completed the survey. Ninety-five percent of respondents agreed that this case gave them the opportunity to practice using acid-base analysis in patient care, and ninety-eight percent of respondents agreed that this simulated case was helpful to their understanding of acid-base concepts. Students commented that they appreciated the opportunity to practice using concepts learned in a classroom setting in a patient encounter.

Conclusion
Students agreed that participating in a manikin-based simulated patient encounter allowed them to practice using acid-base physiology concepts, leading to a better understanding of its use in patient care.