The purpose of this study is to monitor sleep in patients using breathing machines, because little is known about sleep when patients use masks to help their breathing. We'd like to compare sleep in patients using masks to that in patients with a tube in their throats.

Sleep in critically-ill patients is commonly severely fragmented, and sleep architecture is altered as compared to a healthy person. This abnormal sleep may cause some important adverse psychological and physiological consequences. Noise, light, patient-care activities, pain, or medications are some of the contributing factors to sleep disruption in the ICU. Recent evidence also suggests that invasive mechanical ventilation (IMV) itself may lead to sleep fragmentation in the ICU. Noninvasive ventilation (NIV) is a well-established, relatively new form of ventilation which improves sleep quality or gas exchange in some patients with chronic hypoventilatory disorders. Although sleep may be disrupted due to discomfort from the mask or air leaking during NIV use; intermittent use of NIV may result in better sleep quality between NIV sessions. The effects of NIV on sleep in the acute care setting have not yet been studied.

The purpose of the study is to describe the sleep architecture of a cohort of critically-ill patients using NIV, comparing findings to a reference group of patients using (IMV).

Inclusion Criteria:

• Age > 18 yrs
• Receiving invasive or noninvasive mechanical ventilation
• Anticipated further ventilation of at least 24-hour duration for IMV and 8 hours/ 24 hours for NIV

Exclusion Criteria:

• Pre-morbid diseases that could interfere with interpretation of sleep monitoring including CNS disorders (strokes, encephalopathic states), dementia, and known sleep disorders
• On home BiPAP or CPAP
• Depressed sensorium as evidence by Glasgow Coma Score < 10, need for continuous sedation with Riker Score < 2 and inability to follow verbal commands for sustained 3 hours
• Presence of head trauma, psychiatric illness (including use of antidepressant medication), anoxic brain injury, drug overdose or uncontrolled seizure disorder
• Severe hemodynamic instability (BP< 90 mmHg despite vasopressor therapy) and sepsis
• Recalcitrant hypoxemia (inability to sustain SaO2 > 88%)
• Considered as unstable by ICU team (hemodynamic instability, acute uncontrolled GI bleeding, acute cardiac ischemia or arrhythmias)

Critically ill patients undergoing invasive or noninvasive mechanical ventilation in medical ICU and CCU at Tufts New England Medical Center