Journal of Applied Physiology, Vol 53, Issue 4 908-913, Copyright © 1982 by American Physiological Society
Right ventricular pressure response to +GZ acceleration stress
J. E. Whinnery and M. H. Laughlin
Measurements of right ventricular pressure in miniature swine were made at
+Gz levels from +1 through +9 Gz. Polyethylene catheters were chronically
placed in the cranial vena cava of five 2-yr-old female miniature swine
(35-50 kg). The catheters were large enough to allow the introduction of a
Millar pressure transducer into the venous system for placement in the
right heart. The animals were fitted with an abdominal anti-G suit,
restrained in a fiberglass couch, and exposed to the various +Gz levels on
a centrifuge while fully conscious and unanesthetized. Right ventricular
pressure and heart rate were measured during and for 2 min following 30-s
exposures to each level of +Gz stress. The maximum right ventricular
systolic pressure observed during +Gz was 200 Torr at +5 Gz with the
maximum diastolic pressure being 88 Torr observed at +5 Gz. Mean heart
rates were 200-210 beats/min at all levels of +Gz greater than or equal to
+3 Gz when the animal remained stable. Mean maximum right ventricular
pressures during +Gz stress were observed to increase through +5 Gz (85
Torr) and to decrease at higher levels of +Gz, indicating that through +5
Gz there is at least a partial compensation during acceleration stress.
Decompensation in response to the stress began to occur during acceleration
above +5 Gz with all animals decompensating during +9 Gz.
