Institute of Forensic Medicine, University of Cologne says

Dying in a head-down position
is rare
and autopsy may reveal
no morphological findings
which explain the cause of death sufficiently.

Functional changes,
mainly postural changes
of circulation must be considered
to explain the cause of death.

Two cases of death are reported
where death occurred
in a head-down position,
among them an autoerotic accident
with suspension of a man
head-down

in a sack.