A Low-Cost Cocoa-Opacified Hematemesis Simulant for Manikin-Based Airway and Endoscopic Visualization Training: Formulation Rationale, Targeted Review, and Cost Analysis.

High-fidelity manikin scenarios for contaminated airway management and upper gastrointestinal bleeding (UGIB) depend on blood or hematemesis simulants that reliably occlude optics and reproduce the visual gestalt of real blood under high-intensity video laryngoscopy and flexible endoscopy lighting. Commercially available simulated blood products are frequently optimized for reusability, stain resistance, and compatibility with procedural trainers, and can be cost-prohibitive for repeated high-volume "soiling" curricula. However, many simulated blood products do not report optical opacity or camera-obscuration performance for this specific use case. We performed a targeted technical review of blood and bleeding simulant strategies used in manikin-based training and adjacent materials science literature, and we describe a low-cost, reproducible hematemesis analog composed of three packets of a raspberry-flavored powdered beverage mix - Crystal Light Sugar-Free Raspberry Ice Drink Mix (made from maltodextrin, citrate salts, calcium phosphate, organic acids, and FD&C dyes) - dispersed with 20 g of unsweetened cocoa powder - Hershey's Cocoa - in 1 L of water using an immersion blender. In preliminary qualitative bench use, this particulate suspension formulation produced a dark red-brown appearance and visually reduced light transmission compared with the dye-only beverage mixture. Objective optical, rheologic, and comparative performance testing was not performed in this introductory report. Direct material cost was approximately $1.66/L using representative U.S. retail pricing, compared with $7-$29/L for selected commercial powders and premixes, although this comparison reflects direct consumable cost only and does not establish performance equivalence. Limitations include sedimentation and phase separation over time (necessitating re-homogenization) and potential staining of the manikin; a spot test on non-critical surfaces is recommended prior to implementation. Because the formulation contains organic particulates, it should not be introduced into patient-care endoscope working channels or equipment intended for later clinical use unless local reprocessing staff verify complete clearance for the specific device. This report is intended as a preliminary formulation and microcosting analysis; future work should quantify viscosity (including shear-thinning behavior), density, spectral absorbance/scattering, and material compatibility to support standardization across simulation programs.