Which of the following is a key feature of portable digital diagnostic devices?

A key feature of portable digital diagnostic devices is the ability to provide real-time monitoring and feedback. This capability is essential in many clinical and emergency settings where immediate data on a patient's condition can significantly impact treatment decisions and outcomes. Real-time monitoring allows healthcare providers to observe changes and respond promptly, enhancing patient safety and care efficacy.

While connecting to mainframes and operating in offline mode can be features of some devices, they do not directly relate to the core function of portability in diagnostics. Performing complex surgeries is not a function of portable diagnostic devices; rather, these devices are primarily designed for assessment and monitoring rather than surgical interventions. Therefore, the focus on real-time capabilities aligns directly with the critical role that portable diagnostic tools play in healthcare.