Hi Old Salt , the issue you raised about how much easier it is to pump a lower blood volume applies to a lot of ME research, and probably many other diseases including EDS. In the absence of really understanding the mechanisms of the disorder, how do we tell if something we are looking at is a primary cause of the disorder, secondary to the primary cause, or compensatory to cope with the disorder? Low blood volume could be any of these. Cheney has commented that many of our issues, and the progression of symptoms, resembles that of heart failure. Is the problem caused by a failing heart, or as others have suggested do our hearts fail due to insufficient blood? These are questions that are not answered. Alex.