Student perceptions of both classic and 3-box (OB) variants of the Darrow-Yannet diagram for learning water balance physiology

Purpose: To determine the perceived effectiveness of teaching water balance physiology to incoming first-year medical students at two campuses using either a classic 2-box Darrow-Yannet (D-Y) diagram or a 3-box (Out of Body or OB) variant of the D-Y diagram. Introduction and Hypotheses: The Darrow-Yannet diagram is a 2-box tool with which students learn water balance physiology. Boxes represent extracellular (ECF) and intracellular (ICF) fluid compartments. In a new (2022) 3-box OB variant of the D-Y diagram, an out-of-body (OB) compartment is adjacent to the ECF. These compartments are separated by an epithelial layer which depicts proteins involved in controlling or carrying out water transfer between the OB and ECF compartments. In July 2024, water balance physiology was taught to incoming medical students at two sister campuses. One (LECOM at Elmira) used the 2-box tool to model changes to specific types of ECF volume contractions and expansions. The other (LECOM at Seton Hill) used the 3-box tool in class but kept 2-box tools in review materials for the final exam which was written at a third campus (LECOM at Erie). Six weeks after the material was presented, surveys gathered student perceptions of their training in water balance physiology. There were three hypotheses: 1) that students would report better understanding of water balance, 2) that the 2-box D-Y diagram would help them learn it, and 3) the 3-box (OB) variant would be at least as effective as the 2-box D-Y diagram. Results: At LECOM-Elmira, the only tool used was the classic D-Y diagram. LECOM-Seton Hill used the OB variant in its main session and the 2-box model for post-class activities. Students (n=12) reported significant improvements in knowledge of water balance physiology (p<0.001). 4 of 4 students at LECOM-Elmira agreed or strongly agreed that the classic 2-box D-Y diagram helped them learn water balance physiology. At LECOM-Seton Hill, 3 of 8 agreed or strongly agreed that the 2-box D-Y diagram helped them, 4/8 were neutral, and 1 of 8 disagreed. This difference between results on this question at LECOM-Elmira vs. LECOM-Seton Hill was not significant (p= 0.10). At LECOM-Seton Hill, survey results for both the 2-box question and the corresponding 3-box question were identical, so there was no difference in the perceived helpfulness of 2-box vs 3-box tools (p= 0.5). Conclusions: The first hypothesis was supported, the second where it was exclusively used (LECOM-Elmira), and the third was also supported. Students reported improvements in understanding water balance following the session. At LECOM-Elmira, where it was the only tool used, the classic 2-box D-Y diagram was perceived as effective in helping them learn water balance physiology by 100% of the survey responders. At LECOM-Seton Hill, 7 of 8 students found were either neutral or positive on each question on either the two-or-three box D-Y diagram was similarly helpful. Given low participation but generally positive results, a modified version of this pilot study will be repeated in 2025. This survey will be given as close to the teaching date as possible to capture perceptions from a larger percentage of possible respondents. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.