Hypercapnia in Orthostatic Hypotension

Inclusion Criteria: * Age ≥18 years * Male and Female * Non - smokers. * Able and willing to provide informed consent. * Ability to travel to Libin Cardiovascular Institute Autonomic Testing Lab at the University of Calgary, Calgary, AB. Exclusion Criteria: * Medical therapies or medications which could interfere with testing of autonomic function * Participants with somatization or severe anxiety symptoms will be excluded * Pregnant or breast-feeding females * Inability to tolerate mask for the duration of the study * Subjects who require portable oxygen at rest or with exercise * Subjects with chronic heart failure or severe pulmonary disease who are unable to climb one flight of stairs due to shortness of breath. * Presence of failure of other organ systems or systemic illness that can affect autonomic function or the participant's ability to cooperate. These include: dementia, alcohol and/or drug abuse, cerebrovascular disease, kidney or liver disease, surgical procedures where the nerves of the sympathetic nervous system have been cut. * Other factors which in the investigator's opinion would prevent the participant from completing the protocol, including poor compliance during previous studies.