The Looming Shadow of DVT
DVT or Deep Vein Thrombosis is a condition which is known to affect airline travellers, and office workers. Thrombosis occurs when people are sitting still for long periods of time. Blood clots form in the arteries where blood is settling over long periods of time - as opposed to circulating properly when moving briskly around. This tends to be more of a problem in the lower legs when sitting, but can occur in any part of the body when fully reclined.
Deep Vein Thrombosis, logically is a thrombosis, or blood clot that develops in a deep-set vein far below the skin's surface in the body. This causes blood to pool behind the clot, stretching the linings of the vein, and causing compression, swelling and a great deal of pain in the surrounding tissue. DVT in the chest is usually fatal, as the swelling vein compresses nearby arteries and chokes off blood supply to the lungs - or the clot forms directly in the lungs themselves. In either case, emergency treatment is required to save the person's life.
DVT risks increase particularly after long periods of physical stillness, and especially with dehydration.
VR and DVT
Whilst there have as yet been no official studies on this, there is enough circumstantial evidence from other pursuits - remaining seated in aircraft for long periods, or sitting in office chairs day in day out - to suggest a strong likelihood that DVT will also affect fully immersive virtual reality interfaces, when body movement is not part of the immersion.
Fishbowl VR and DVT
Fishbowl VR, sometimes called window on world Virtual Reality, or WOW - not to be confused with the online gameworld of the same name - is the type of VR when a user sits at a computer terminal, peripherally aware of the physical world around them, and interfacing with the virtual world through a monitor screen.
Such a position bears a strong resemblance to that of an office worker, concentrating on the data on the screen for hours at a time. However, this is often additionally performed as a leisure activity as well as one of work, with the two frequently intermixing for periods of many hours in length, for many days without a significant break.
Such activity is therefore, of immense likelihood of predisposition to deep vein thrombosis, as well as a myriad of other conditions.
Fully Immersive VR and DVT
Fully immersive VR occurs when enough of the participant's five senses are completely immersed into the simulation as to produce a perceived sense of true presence within the simulation world. It has already been demonstrated by countless studies and experiments that vision and sound alone are enough to provide this sense of presence. Adding touch, smell and taste is therefore simply an enhancement, which leads to greater long-term believability.
Immersive virtual reality systems both can and will go several steps further than this. Much of their real potential lays in replacing or overloading physical characteristics which do not function properly alone - virtual voices, the sensation of physical limbs, when such do not exist, or simply do not work, new components of a physical form, which do not work in the physical world.
When immersive, whole body interfaces that do not require much movement from the individual, that instead interpret electrical signals from the brain, and re-route them to virtual limbs rather than physical, when sensory stimulation is applied directly to the body, and people use them on a regular basis, then we are very likely to encounter a set of circumstances far more profound than found in fishbowl VR. It is, in fact, not a great leap to surmise that physical body movement in direct brain interface, or virtual prosthetic based VR worlds will be exhibited to a far lesser degree than window on world based systems.
Fishbowl VR DVT risks are fairly easy to eliminate. Just as with office work, a similar posture has a similar remedy. Simply tapping the feet whilst engaged in the VR world, or shifting legs around frequently, will keep blood flowing round the extremities. If hands are not being used to type, or control another peripheral, drumming the fingers has the same effect.
Posture at the physical terminal is also important - particularly with uncrossed legs spaced slightly apart, to ensure veins are not under any external compression, if you expect to be interfacing for any significant period of time.
Fully Immersive VR
With such fully immersive systems as described previously, the solutions are a lot less readily apparent. Clearly, if possible, arms and legs should be uncrossed, and, if relaxing, whilst using the interface, a laying position, with feet slightly apart, arms apart and fingers splayed - depending on the degree of computer override of sensation - seems best.
Anti clotting agents are already available, to care for the physical form. Blueberry, pine bark and ginger have all shown themselves to have anti-clotting properties, as well as maintaining arterial cell walls in good condition. A mix of all three, supplemented into the bloodstream, would radically reduce the risk of blood clotting due to pooling, for full-immersion situations where physical breaks are likely impossible due to interface rigging or system shock. It is quite likely that repeated switching between two very different, but equally sensorialy real worlds, once an hour for an extended period of time, would have a traumatic effect on the nervous system which more than offsets the benefit gained to the physical system of the VR participant.
Whilst Deep Vein Thrombosis is an issue that will arise to challenge long-term immersion in VR environments, both fishbowl, and full immersion, particularly as the leisure use of such systems continues to increase exponentially, sufficient means exist to negate, or medicate DVT risks into negligibility.
Being-here, now... (Essay on the future of Immersive VR)