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This paper describes an activity using a dog treat ball to introduce systems of first-order differential equations. Beads are placed in the first of two hemispherical chambers of a food-dispensing dog toy. As the ball is turned, students track the number of beads in the first chamber, the second chamber, and the exterior of the ball. Students develop a working assumption, write a system of differential equations to model the number of beads in each region, and use a spreadsheet to compare their experimental and model results.

Background: This retrospective analysis of prospectively collected data from the PROPPR study describes volatile anesthetic use in severely injured trauma patients undergoing anesthesia., Methods: After exclusions, 402 subjects were reviewed of the original 680, and 292 had complete data available for analysis. Anesthesia was not protocolized, so analysis was of contemporary practice., Results: The small group who received no volatile anesthetic (n = 25) had greater injury burden (Glasgow Coma Scale P  = 0.05, Injury Severity Score P  = 0.001, Revised Trauma Score P  = 0.03), higher 6- and 24-hour mortality ( P  < 0.001), and higher incidence of systemic inflammatory response syndrome ( P  = 0.003) and ventilator-associated pneumonia ( P  = 0.02) than those receiving any volatile (n = 267). There were no differences in mortality between volatile agents at 6 hours ( P  = 0.51) or 24 hours ( P  = 0.35). The desflurane group was less severely injured than the isoflurane group. Mean minimum alveolar concentration was < 0.6 and lowest in the isoflurane group compared to the sevoflurane and desflurane groups (both P  < 0.01). The incidence of systemic inflammatory response syndrome was lower in the desflurane group than in the isoflurane group ( P  = 0.007)., Conclusion: In this acutely injured trauma population, choice of volatile anesthetic did not appear to influence short-term mortality and morbidity. Subjects who received no volatile were more severely injured with greater mortality, representing hemodynamic compromise where volatile agent was limited until stable. As anesthetic was not protocolized, these findings that choice of specific volatile was not associated with short-term survival require prospective, randomized evaluation., Competing Interests: No commercial funding was received for this work. DL and CL were recipients of a summer research scholarship from McGovern Medical School to initiate the project. SS is supported by the Biostatistics/Epidemiology/Research Design component of the Center for Clinical and Translational Sciences, currently funded through a National Center for Advancing Translational Sciences grant awarded to the University of Texas Health Science Center at Houston. This content does not represent the official views of the NCATS. EGP serves as a medical consultant for Lucid Lane, which offers virtual assistance to postsurgical patients with opioid management, and as a speaker for Haemonetics, Inc., neither of which have any relationship to the current study. None of the other authors have conflicts of interest to declare., (Copyright © 2023 Baylor University Medical Center.)