• W L Krause, J C Leiter, S Marsh Tenney, and J A Daubenspeck.
• 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
• Respir Physiol. 2000 Oct 1; 123 (1-2): 131-41.

AbstractHypoxia 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.

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