CodeBlue is a wireless infrastructure designed for emergency medical care, integrating low-power, wireless vital sign sensors, PDAs, and PC-class systems. It aims to enhance first responders' ability to assess patients on scene, ensure seamless data transfer among caregivers, and facilitate efficient hospital resource allocation. The system is designed to scale to very dense networks with thousands of devices and extremely volatile network conditions, supporting reliable, ad hoc data delivery, flexible naming and discovery, and a decentralized security model. Wireless sensor networks have the potential to significantly impact emergency medical care by capturing continuous, real-time vital signs from patients and relaying the data to handheld computers. Wearable sensor nodes can store patient data, supplementing back-end storage systems and paper charts. In mass casualty events, sensor networks can improve triage and treatment of multiple patients equipped with wireless monitors. CodeBlue addresses challenges in ad hoc network formation, naming and discovery, security, and data filtration and aggregation. It operates across a wide range of devices, including low-power "motes," PDAs, and PCs, and addresses the special robustness and security requirements of medical care settings. The system is designed to be scalable, robust, and secure, with a flexible security model allowing a range of policies to be implemented. Research challenges include secure, reliable communication, computational limitations, and programming coordination. CodeBlue aims to bring together these challenges into a coherent system to provide routing, addressing, security, and prioritization of data. The infrastructure is necessary to realize the benefits of next-generation wireless devices in emergency and disaster response. Current status includes initial design of CodeBlue and prototypes of several components, with ongoing development of an ECG mote and testing of a lightweight public key infrastructure based on elliptic curve cryptography.CodeBlue is a wireless infrastructure designed for emergency medical care, integrating low-power, wireless vital sign sensors, PDAs, and PC-class systems. It aims to enhance first responders' ability to assess patients on scene, ensure seamless data transfer among caregivers, and facilitate efficient hospital resource allocation. The system is designed to scale to very dense networks with thousands of devices and extremely volatile network conditions, supporting reliable, ad hoc data delivery, flexible naming and discovery, and a decentralized security model. Wireless sensor networks have the potential to significantly impact emergency medical care by capturing continuous, real-time vital signs from patients and relaying the data to handheld computers. Wearable sensor nodes can store patient data, supplementing back-end storage systems and paper charts. In mass casualty events, sensor networks can improve triage and treatment of multiple patients equipped with wireless monitors. CodeBlue addresses challenges in ad hoc network formation, naming and discovery, security, and data filtration and aggregation. It operates across a wide range of devices, including low-power "motes," PDAs, and PCs, and addresses the special robustness and security requirements of medical care settings. The system is designed to be scalable, robust, and secure, with a flexible security model allowing a range of policies to be implemented. Research challenges include secure, reliable communication, computational limitations, and programming coordination. CodeBlue aims to bring together these challenges into a coherent system to provide routing, addressing, security, and prioritization of data. The infrastructure is necessary to realize the benefits of next-generation wireless devices in emergency and disaster response. Current status includes initial design of CodeBlue and prototypes of several components, with ongoing development of an ECG mote and testing of a lightweight public key infrastructure based on elliptic curve cryptography.