The roles of orthostatic hypotension,
orthostatic tachycardia, and subnormal erythrocyte volume in the pathogenesis of
the chronic fatigue syndrome
Am J Med Sci 2000 Jul;320(1):1-8
Streeten DH, Thomas D, Bell DS
Department of Medicine, State University of New York
Health Science Center, Syracuse 13210, USA.
Orthostatic hypotension during upright tilt is an important
physical disorder in patients with chronic fatigue syndrome. We
have tested its occurrence during prolonged standing, whether it
is correctable, and whether reduced circulating erythrocyte
volume is present.
Fifteen patients were randomly selected from a large population
of patients with chronic fatigue syndrome, studied, and observed
for several years (by DSB). Blood pressure (BP) and heart rate
(HR) measured with Dinamap every minute for 30 minutes supine
and 60 minutes standing were compared with these findings in 15
healthy age- and gender-matched control subjects and later
during lower body compression with military antishock trousers
(MAST). Plasma catecholamines and circulating erythrocyte and
plasma volumes were also measured by isotopic dilution methods.
Abnormal findings in the patients included excessive orthostatic
reductions in systolic (P < 0.001) and diastolic BP (P < 0.001)
and excessive orthostatic tachycardia (P < 0.01), together with
presyncopal symptoms in 11 of the 15 patients and in none of the
control subjects after standing for 60 min. Lower body
compression with the MAST restored all orthostatic measurements
to normal and overcame presyncopal symptoms within 10 min.
Circulating erythrocyte but not plasma volumes were subnormal in
the 12 women (P < 0.01) and plasma norepinephrine concentration
rose excessively after standing for 10 min.
Delayed orthostatic hypotension and/or tachycardia caused by
excessive gravitational venous pooling, which is correctable
with external lower-body compression, together with subnormal
circulating erythrocyte volume, are very frequent, although not
invariably demonstrable, findings in moderate to severe chronic
fatigue syndrome. When present, they may be involved in its