ACCESSING CHEMOSENSITIVITY AND VENTILATORY STABILITY FROM TRANSIENT STIMULI

The degree of ventilatory stability of human subjects is inferred from the presence or absence of oscillations in ventilation in response to a brief CO2 disturbance using the method of pseudorandom stimulation. Simultaneously, chemosensitivity is measured. Stability and chemosens itivity are compared in hyperoxia between wakefulness and stage 2 non- rapid eye movement (NREM) sleep and between normoxia and hyperoxia awa ke. Stability is unchanged between wakefulness and sleep but chemosens itivity decreases in sleep. In contrast, stability is reduced in normo xia whereas chemosensitivity is larger than in hyperoxia. It is conclu ded that chemosensitivity and ventilatory stability may change indepen dently, implying that chemosensitivity alone is not an adequate indica tor of the likelihood of a subject to exhibit periodic breathing.