This research study is being done to evaluate the effectiveness of using the sharpened Romberg test to screen for impaired postural control in patients with impaired or altered breathing patterns.

The effects of hypocapnia on the postural system have not previously been adequately investigated. The specific aim of this study is to evaluate the effects of hypocapnia on postural standing balance using the sharpened Romberg test (SRT). There is very little research in this area, even though there is significant clinical relevance, ranging from individuals with conditions affecting ventilation (respiratory conditions, cardiac conditions, concussions, medications, post-surgical states requiring ventilatory support etc). The design of the experiment consists of testing healthy subjects and measuring their standing balance with SRT before and after they deliberately lower their carbon dioxide levels by increased ventilation over 2min. End-tidal CO2 (ETCO2) will be used to estimate the blood carbon dioxide level during the experimental procedures. ETCO2 will be measured using the Masimo, Emma Capnometer device. The device is a measurement tool that reads the end tidal carbon dioxide level on its display. The results will then be compared to the normal pre-hypocapnic SRT to assess how hypocapnia affects standing balance.

Inclusion Criteria:

- Research subject conditions that may result in alterations of ventilatory control (capnic status) and balance will be specifically reviewed as criteria for participation.

Exclusion Criteria:

• Current pregnancy in women, alcohol use within the past 3 days prior to the experiment, history of balance problems (e.g., vertigo, neuropathy, central or peripheral vestibular disorders), and musculoskeletal disorders affecting the ability to perform a SRT in participants.
• Patients currently taking carbonic anhydrase inhibitors, opioids, benzodiazepines, hypnotics, first-generation H1 antihistamines, amphetamines, and first-generation antipsychotics.
• Patients with a history of insomnia, sleep apnea, circadian rhythm disturbances, narcolepsy, movement disorders, chronic low blood pressure, fainting spells, multiple concussions, seizure disorders, migraines, severe headaches and panic attacks.
• If the patient took medications known to cause prolonged QTc interval and other cardiac arrhythmias, the researchers will exclude the patient from the study.