Basic biomedical instrumentation for underwater human biotelemetry

Clinical devices used in everyday clinical practice for assessing health status cannot be used underwater, because of a variety of problems related to the liquid environment, its salinity and the hydrostatic working pressure. Thus, underwater medicine is mainly based on the results of a series of 'physiological models' of underwater diving that are considered to be valid surrogate and inferences from the clinical world; this approach, due to the lack of direct physiological measurements in the true environment, induced many drawbacks and/or mistakes in investigating human underwater physiology. Indeed, both processes are intrinsically uncertain and scientifically incorrect. Thus, the transfer to the underwater environment of routine clinical instruments represents a great improvement, in terms of practice of medicine knowledge, just as it is the case of space medicine. This task required the design of novel underwater diagnostic and monitoring instrumentation and the development of ad-hoc support infrastructure. In particular, we developed a minimum set of innovative underwater medical instruments to collect data related to heart rate, cardiac electric activity, cardiac morphology and function, arterial blood pressure and oxygen blood saturation, in addition to environmental information on water temperature and hydrostatic pressure. In the present paper we will briefly describe the devices we designed and manufactured for the underwater assessment of physiological parameters; moreover we report about some important results in terms of advancement of knowledge in underwater physiology, using underwater measurements by novel diagnostic instrumentation. In particular, new acquisitions on blood pressure and cardiac functional responses during different diving activities will be described.