Acute hypoxia activates human 8-12 Hz physiological tremor.
Hypoxia causes arousal. Therefore, we hypothesized that hypoxia activates the human somatomotor system and should augment tremor. We determined the effects of hypoxia, PET(O2) = 45+/-2.2 mm Hg, hypocapnia, and the hypocapnic-hypoxic interaction on finger tremor during elastic loading. A total of 12 healthy male volunteers were studied during five conditions: eupnea, hypocapnic hypoxia, eucapnic hypoxia, hypocapnic normoxia, and eucapnic normoxia. Acceleration power spectra were computed to quantify 8-12 Hz tremor. Hypoxia significantly augmented 8-12 Hz physiological tremor (P=0.002). Furthermore, six subjects (50%) exhibited significantly more tremor during hypocapnic hypoxia (hH) than during eucapnic hypoxia (eH). We conclude that acute hypoxia augments 8-12 Hz physiological tremor, and hypocapnia further augments this tremor in some subjects. As such, hypoxic tremor is activated physiological tremor, and entrainment of spinal alpha-motoneuron activity may be the final common pathway.
Krause
W L
WL
Medical Services, Pulmonary and Critical Care Unit, Massachusetts General Hospital and Harvard Medical School, Bulfinch 148, 55 Fruit Street, Boston, MA 02114, USA. wkrause@partners.org
Leiter
J C
JC
Marsh Tenney
S
S
Daubenspeck
J A
JA
D000208:Acute Disease; D000328:Adult; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood; D006801:Humans; D016857:Hypocapnia / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012129:Respiratory Function Tests; D014202:Tremor / Q000503:physiopathology*
D002245:Carbon Dioxide