Introduction: The usefulness of heart rate variability (HRV) and heart rate complexity (HRC) analysis as a potential triage tool has been limited by the inability to perform real-time analysis on a portable, handheld monitoring platform. Through a multidisciplinary effort of academia and industry, we report on the development of a rugged, handheld and noninvasive device that provides HRV and HRC analysis in real-time in critically ill patients. Methods: After extensive re-engineering, real-time HRV and HRC analyses were incorporated into an existing, rugged, handheld monitoring platform. Following IRB approval, the prototype device was used to monitor 20 critically ill patients and 20 healthy controls to demonstrate real-world discriminatory potential. Patients were compared to healthy controls using a Student's t test as well as repeated measures analysis. Receiver operator characteristic (ROC) curves were generated for HRV and HRC. Results: Critically ill patients had a mean APACHE-2 score of 15, and over 50% were mechanically ventilated and requiring vasopressor support. HRV and HRC were both lower in the critically ill patients compared to healthy controls (ρ < 0.0001) and remained so after repeated measures analysis. The area under the ROC for HRV and HRC was 0.95 and 0.93, respectively. Conclusions: This is the first demonstration of real-time, handheld HRV and HRC analysis. This prototype device successfully discriminates critically ill patients from healthy controls. This may open up possibilities for real-world use as a trauma triage tool, particularly on the battlefield.