A Systematic Framework for Analyzing Body Fluid Disturbances

Objective: Textbooks typically simplify body fluid disturbances by presenting only the causes and final outcomes, omitting crucial intermediate steps that link causes to effects. This approach may lead to students' confusion and limit their comprehension. This study aims to unfold the common logical steps of how these disturbances should be understood and analyzed without leaving any gaps in logic. These steps form a systematic framework applicable to analyze each type of disturbance and encompasses more clinical correlations, thus appropriate for medical students. Research Questions: 1. What is the logic in the systematic framework? 2. How effective is the systematic framework in facilitating the teaching and learning of the topic? Methods: We conducted a literature review to assess the coverage of body fluid disturbances in physiology textbooks and identified deficiencies in current teaching of the topic. We then reasoned out (unfolded) the temporal sequence (step-by-step) in the development of each type of disturbance from the cause(s) to the final consequences and what parameter(s) may change concurrently from each step. Results: 1. From the cause(s) to the final outcome of each type of disturbance, the following logic is unfolded: a. Check the extracellular fluid volume (ECF) to examine what is/are the primary changes (whether the volume change in ECF is accompanied by the osmolarity change in ECF? If yes, water shifts across the cell membrane results) b. Check the direction of water shift (from ECF to ICF, or vice versa?) as the secondary change. This step is crucial for students to understand each type of disturbance and should not be omitted. c. Check the tertiary changes as concurrent results of water shift including intracellular fluid (ICF) volume and osmolarity, hematocrit (increase or decrease), and the plasma protein concentration and the resulting colloid osmotic pressure. 2. The application of the systematic framework in our teaching has proved its effectiveness and completeness in understanding the topic. The omission of the secondary change in educational resources causes difficulties in students' learning. An analysis of the tertiary changes expands the teaching to encompass more clinical correlations caused by these disturbances. A newly developed flowchart in our poster will show the details of how the application of the systematic framework fills the gaps and provides a cohesive framework for teaching the topic. Conclusions: The development and application of the systematic framework to teach the body fluid disturbances advances physiology education by bridging the gaps and expanding the clinical correlations for medical students. The framework provides a solid foundation for students to learn renal physiology and pathophysiology including water and electrolyte balances and imbalances, and ultimately fosters critical thinking in clinical contexts. 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.