Reply to "Addressing challenges for virtual reality applications in the ICU": from feasibility to clinically meaningful implementation.

Virtual reality (VR) is increasingly explored as an adjunct to rehabilitation in critically ill patients, but its clinical role, optimal application, and safety assessment remain incompletely defined. Our pilot study evaluated whether immersive VR could be integrated into routine cycle-based rehabilitation in selected, awake, consenting ICU patients without clinically relevant physiological instability and with acceptable tolerability, usability, and satisfaction. VR-assisted rehabilitation should not be considered a homogeneous intervention, as its effects are likely to depend on patient selection, neurological and functional status, characteristics of the immersive environment, physical workload, interaction intensity, duration, frequency, and cumulative exposure. Future studies should distinguish pragmatic evaluation from mechanistic investigation. Standard physiological monitoring remains appropriate for bedside feasibility studies, whereas electroencephalography, heart-rate variability, electrodermal activity, and other biosignals may help characterize autonomic and neurocognitive responses in hypothesis-driven research. Standardized assessment of cybersickness, adverse events, premature session termination, workflow, staff burden, device reliability, infection prevention, and governance will also be essential. Our findings provide preliminary, hypothesis-generating evidence that VR-assisted cycling is feasible and potentially safe in carefully selected ICU patients. Multicentre studies should now determine whether this approach improves rehabilitation engagement, functional recovery, patient experience, and other clinically meaningful outcomes.