{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T11:18:12Z","timestamp":1785410292828,"version":"3.56.0"},"reference-count":36,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T00:00:00Z","timestamp":1784160000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000182","name":"U.S. Army Medical Research and Development Command","doi-asserted-by":"publisher","award":["CO240020"],"award-info":[{"award-number":["CO240020"]}],"id":[{"id":"10.13039\/100000182","id-type":"DOI","asserted-by":"publisher"}]},{"award":["CO240020"],"award-info":[{"award-number":["CO240020"]}],"id":[{"id":"https:\/\/ror.org\/03cd02q50","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Bioengineering"],"abstract":"<jats:p>In this work, the real-time measurement of compensatory reserve metrics is compared during a simulated central hypovolemia clinical research study. We hypothesized that values generated from the compensatory reserve measurement (CRM) device would be statistically similar to those values generated from the compensatory reserve index (CRI) device. A study was conducted to collect data from noninvasive photoplethysmography sensors to validate the CRM against an FDA-cleared CRI device. Participants were placed in a lower body negative pressure (LBNP) chamber and underwent exposure to a stepwise protocol of increasing negative pressure. Data from both algorithmic devices were evaluated using multiple approaches: median error, median absolute error, and pooled Pearson correlations. Data were compared from 20 participants through the duration of the experiment. Pooled correlation analysis between CRM and CRI for all subjects and LBNP steps achieved R2 = 0.859, showing strong linear agreement. Bland\u2013Altman analysis revealed a near-zero mean bias between CRM and CRI (0.13%). Each metric allowed for a mean early measurement time of 20.52 min for CRM and 17.92 min for CRI. Consistent with our hypothesis, the CRM device performed similarly to CRI, demonstrating that both models can track compensatory status changes with progressive central hypovolemia. The early, real-time predictive tracking of compensatory changes can be valuable for continuous monitoring and triaging in prehospital trauma environments.<\/jats:p>","DOI":"10.3390\/bioengineering13070817","type":"journal-article","created":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T03:12:38Z","timestamp":1784257958000},"page":"817","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Real-Time Comparison of Machine Learning-Enabled Devices for Measuring Compensatory Reserve Status"],"prefix":"10.3390","volume":"13","author":[{"given":"Carlos","family":"Bedolla","sequence":"first","affiliation":[{"name":"Expeditionary Medical Systems Department, U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, TX 78234, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4325-409X","authenticated-orcid":false,"given":"Jose M.","family":"Gonzalez","sequence":"additional","affiliation":[{"name":"Expeditionary Medical Systems Department, U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, TX 78234, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryan","family":"Ortiz","sequence":"additional","affiliation":[{"name":"Expeditionary Medical Systems Department, U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, TX 78234, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Krysta","family":"Amezcua","sequence":"additional","affiliation":[{"name":"Expeditionary Medical Systems Department, U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, TX 78234, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sofia I.","family":"Hernandez Torres","sequence":"additional","affiliation":[{"name":"Expeditionary Medical Systems Department, U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, TX 78234, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9246-0554","authenticated-orcid":false,"given":"Victor A.","family":"Convertino","sequence":"additional","affiliation":[{"name":"Battlefield Health & Trauma Center for Human Integrative Physiology, U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, TX 78234, USA"},{"name":"Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA"},{"name":"Department of Emergency Medicine, University of Texas Health Science Center, San Antonio, TX 78229, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0293-4937","authenticated-orcid":false,"given":"Eric J.","family":"Snider","sequence":"additional","affiliation":[{"name":"Expeditionary Medical Systems Department, U.S. Army Institute of Surgical Research, JBSA Fort Sam Houston, San Antonio, TX 78234, USA"},{"name":"Department of Surgery, University of Texas Health Science Center, San Antonio, TX 78229, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"S431","DOI":"10.1097\/TA.0b013e3182755dcc","article-title":"Death on the Battlefield (2001\u20132011): Implications for the Future of Combat Casualty Care","volume":"73","author":"Eastridge","year":"2012","journal-title":"J. Trauma Acute Care Surg."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"780","DOI":"10.1017\/S1049023X23006428","article-title":"Epidemiology of Trauma-Related Hemorrhage and Time to Definitive Care across North America: Making the Case for Bleeding Control Education","volume":"38","author":"Jones","year":"2023","journal-title":"Prehospital Disaster Med."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"504","DOI":"10.1097\/TA.0000000000003820","article-title":"Time to Early Resuscitative Intervention Association with Mortality in Trauma Patients at Risk for Hemorrhage","volume":"94","author":"Deeb","year":"2023","journal-title":"J. Trauma Acute Care Surg."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1053","DOI":"10.1097\/TA.0b013e3182aa811a","article-title":"Running on Empty? The Compensatory Reserve Index","volume":"75","author":"Moulton","year":"2013","journal-title":"J. Trauma Acute Care Surg."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"986","DOI":"10.1097\/01.sla.0000259433.03754.98","article-title":"Causes of Death in US Special Operations Forces in the Global War on Terrorism: 2001\u20132004","volume":"245","author":"Holcomb","year":"2007","journal-title":"Ann. Surg."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Meza Monge, K., Rosa, C., Sublette, C., Pratap, A., Kovacs, E.J., and Idrovo, J.-P. (2024). Navigating Hemorrhagic Shock: Biomarkers, Therapies, and Challenges in Clinical Care. Biomedicines, 12.","DOI":"10.3390\/biomedicines12122864"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"267","DOI":"10.1152\/advan.00050.2015","article-title":"Venous Return and Clinical Hemodynamics: How the Body Works during Acute Hemorrhage","volume":"39","author":"Shen","year":"2015","journal-title":"Adv. Physiol. Educ."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"807","DOI":"10.1152\/physrev.00006.2018","article-title":"Lower Body Negative Pressure: Physiological Effects, Applications, and Implementation","volume":"99","author":"Goswami","year":"2019","journal-title":"Physiol. Rev."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Convertino, V.A., Snider, E.J., Hernandez-Torres, S.I., Collier, J.P., Eaton, S.K., Holmes, D.R., Haider, C.R., and Salinas, J. (2023). Verification and Validation of Lower Body Negative Pressure as a Non-Invasive Bioengineering Tool for Testing Technologies for Monitoring Human Hemorrhage. Bioengineering, 10.","DOI":"10.3390\/bioengineering10101226"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1097\/SHK.0000000000000178","article-title":"The Value of Noninvasive Measurement of the Compensatory Reserve Index in Monitoring and Triage of Patients Experiencing Minimal Blood Loss","volume":"42","author":"Nadler","year":"2014","journal-title":"Shock"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"496","DOI":"10.1097\/SHK.0000000000002188","article-title":"The Compensatory Reserve Index for Predicting Hemorrhagic Shock in Prehospital Trauma","volume":"60","author":"Latimer","year":"2023","journal-title":"Shock"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"295","DOI":"10.1097\/SHK.0000000000000959","article-title":"Compensatory Reserve Index: Performance of a Novel Monitoring Technology to Identify the Bleeding Trauma Patient","volume":"49","author":"Johnson","year":"2018","journal-title":"Shock"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"603","DOI":"10.1097\/TA.0000000000001595","article-title":"Comparison of Compensatory Reserve and Arterial Lactate as Markers of Shock and Resuscitation","volume":"83","author":"Johnson","year":"2017","journal-title":"J. Trauma Acute Care Surg."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Techentin, R.W., Felton, C.L., Schlotman, T.E., Gilbert, B.K., Joyner, M.J., Curry, T.B., Convertino, V.A., Holmes, D.R., and Haider, C.R. (2019, January 23\u201327). 1D Convolutional Neural Networks for Estimation of Compensatory Reserve from Blood Pressure Waveforms. Proceedings of the 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Berlin, Germany.","DOI":"10.1109\/EMBC.2019.8857116"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"580","DOI":"10.1097\/SHK.0000000000000559","article-title":"The Compensatory Reserve for Early and Accurate Prediction of Hemodynamic Compromise: A Review of the Underlying Physiology","volume":"45","author":"Convertino","year":"2016","journal-title":"Shock"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1097\/SHK.0000000000001367","article-title":"Tracking DO2 with Compensatory Reserve during Whole Blood Resuscitation in Baboons","volume":"53","author":"Koons","year":"2020","journal-title":"Shock"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"S122","DOI":"10.1111\/trf.16958","article-title":"Identifying Critical DO2 with Compensatory Reserve during Simulated Hemorrhage in Humans","volume":"62","author":"Koons","year":"2022","journal-title":"Transfusion"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"S113","DOI":"10.1097\/TA.0000000000004029","article-title":"Superiority of Compensatory Reserve Measurement Compared with the Shock Index for Early and Accurate Detection of Reduced Central Blood Volume Status","volume":"95","author":"Convertino","year":"2023","journal-title":"J. Trauma Acute Care Surg."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"S98","DOI":"10.1097\/TA.0000000000004377","article-title":"Physiologic Validation of the Compensatory Reserve Metric Obtained from Pulse Oximetry: A Step toward Advanced Medical Monitoring on the Battlefield","volume":"97","author":"Roden","year":"2024","journal-title":"J. Trauma Acute Care Surg."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Ortiz, R., Gonzalez, J., Rodgers, T., Hernandez Torres, S., Convertino, V., and Snider, E.J. (2026). Experimental Evaluation of a Real-Time Implementation of Compensatory Reserve Measurement in a Human Model of Hemorrhagic Shock. Front. Bioeng. Biotechnol., 14.","DOI":"10.3389\/fbioe.2026.1756626"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Gonzalez, J.M., Ortiz, R., Amezcua, K.-L., Bedolla, C., Hernandez Torres, S.I., Weitzel, E.K., Gorantla, V.S., Li, W., Aranyosi, A.J., and Rogers, J.A. (2026). Validation of a Wearable Photoplethysmography-Based Sensor for Compensatory Reserve Measurement Monitoring in Simulated Human Hemorrhage. Sensors, 26.","DOI":"10.3390\/s26082513"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"S104","DOI":"10.1097\/TA.0000000000001511","article-title":"Validation of a Noninvasive Monitor to Continuously Trend Individual Responses to Hypovolemia","volume":"83","author":"Moulton","year":"2017","journal-title":"J. Trauma Acute Care Surg."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Convertino, V.A., Techentin, R.W., Poole, R.J., Dacy, A.C., Carlson, A.N., Cardin, S., Haider, C.R., Holmes, D.R., Wiggins, C.C., and Joyner, M.J. (2022). AI-Enabled Advanced Development for Assessing Low Circulating Blood Volume for Emergency Medical Care: Comparison of Compensatory Reserve Machine-Learning Algorithms. Sensors, 22.","DOI":"10.3390\/s22072642"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1113\/jphysiol.2002.036715","article-title":"Cardiovascular Regulation in the Period Preceding Vasovagal Syncope in Conscious Humans","volume":"549","author":"Julu","year":"2003","journal-title":"J. Physiol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2631","DOI":"10.1093\/eurheartj\/ehp298","article-title":"Guidelines for the Diagnosis and Management of Syncope (Version 2009)","volume":"30","author":"Abe","year":"2009","journal-title":"Eur. Heart J."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1196","DOI":"10.1152\/japplphysiol.00668.2013","article-title":"Estimation of Individual-Specific Progression to Impending Cardiovascular Instability Using Arterial Waveforms","volume":"115","author":"Convertino","year":"2013","journal-title":"J. Appl. Physiol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"406","DOI":"10.1152\/japplphysiol.00640.2013","article-title":"Validation of Lower Body Negative Pressure as an Experimental Model of Hemorrhage","volume":"116","author":"Shade","year":"2014","journal-title":"J. Appl. Physiol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1097\/SHK.0000000000000647","article-title":"The Compensatory Reserve Index Following Injury: Results of a Prospective Clinical Trial","volume":"46","author":"Stewart","year":"2016","journal-title":"Shock"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"S174","DOI":"10.1111\/trf.16498","article-title":"Efficacy of the Compensatory Reserve Measurement in an Emergency Department Trauma Population","volume":"61","author":"Schauer","year":"2021","journal-title":"Transfusion"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"S147","DOI":"10.1097\/TA.0000000000003595","article-title":"Advanced Medical Monitoring for the Battlefield: A Review on Clinical Applicability of Compensatory Reserve Measurements for Early and Accurate Hemorrhage Detection","volume":"93","author":"Convertino","year":"2022","journal-title":"J. Trauma Acute Care Surg."},{"key":"ref_31","unstructured":"(2002). Cardiac Monitors, Heart Rate Meters, and Alarms (Standard No. ANSI\/AAMI EC13: 2002)."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"e27765","DOI":"10.2196\/27765","article-title":"Validation of Heart Rate Extracted from Wrist-Based Photoplethysmography in the Perioperative Setting: Prospective Observational Study","volume":"5","author":"Mestrom","year":"2021","journal-title":"JMIR Cardio"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1186\/s13049-023-01088-8","article-title":"Traumatic Hemorrhage and Chain of Survival","volume":"31","author":"Latif","year":"2023","journal-title":"Scand. J. Trauma Resusc. Emerg. Med."},{"key":"ref_34","first-page":"e91121","article-title":"Integrating Wearable Sensor Data With an AI-Based, Protocol-Flexible Triage Platform to Accelerate Decision-Making During the Golden Hour of Combat Casualty Care","volume":"17","author":"Alnuaimi","year":"2025","journal-title":"Cureus"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"S35","DOI":"10.1016\/j.injury.2014.08.015","article-title":"The ATLS\u00ae Classification of Hypovolaemic Shock: A Well Established Teaching Tool on the Edge?","volume":"45","author":"Mutschler","year":"2014","journal-title":"Injury"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"S184","DOI":"10.1097\/TA.0b013e31829b01db","article-title":"Promoting Early Diagnosis of Hemodynamic Instability during Simulated Hemorrhage with the Use of a Real-Time Decision-Assist Algorithm","volume":"75","author":"Muniz","year":"2013","journal-title":"J. Trauma Acute Care Surg."}],"container-title":["Bioengineering"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2306-5354\/13\/7\/817\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T03:58:30Z","timestamp":1784260710000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2306-5354\/13\/7\/817"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,16]]},"references-count":36,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2026,7]]}},"alternative-id":["bioengineering13070817"],"URL":"https:\/\/doi.org\/10.3390\/bioengineering13070817","relation":{},"ISSN":["2306-5354"],"issn-type":[{"value":"2306-5354","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,16]]}}}