Overnight Polysomnography and Respiratory Volume Monitor

Sleep disordered breathing; specifically obstructive sleep apnea (OSA) is a disease affecting 8-12% of the general population and often more than 70% of the bariatric surgical population. OSA is characterized by the repetitive collapse of the upper airway, causing a reduction or cessation in airflow and decreases in oxygen saturation. These events are resolved by arousals from sleep, reducing sleep quality and leading to excessive daytime sleepiness. An in-laboratory polysomnography (PSG) is the gold standard for the diagnosis of OSA. Previous studies have established obstructive sleep apnea (OSA) as a potential independent risk factor for postoperative complications, adverse surgical outcomes, and longer hospital stays. Patients with OSA have an increase in postoperative complications, the most frequent being oxygen desaturation, postoperative atelectasis and increased postoperative pain. Despite the clear risks, OSA remains under diagnosed with an estimated 25-30% of patients at a high risk for OSA. It has been suggested that OSA events may be even more frequent post operatively because of the residual effects of anesthesia and the use of potent pain medications such as opioids. Postoperatively apneas often go undetected and untreated. The use of supplemental O2 may mask any desaturations and there is no convenient technology to noninvasively monitor ventilation to detect apnea and hypopnea in post-surgical patients. New advances in technology and digital signal processing have led to the development of an impedance based Respiratory Volume Monitor (RVM). The RVM (ExSpiron™, Respiratory Motion, Inc.; Waltham, MA) has been shown to provide accurate real-time, continuous, non-invasive measurements of tidal volume (TV), minute ventilation (MV) and respiratory rate (RR). Our main hypotheses are that the non-invasive, impedance-based RVM monitor will accurately reflect TV, RR and MV during sleep and will detect apneas and hypopneas accurately.