Slower than anticipated enrollment

The purpose of the study is to evaluate the physiological response to application of the Intrathoracic Pressure Regulator (ITPR) in patients with compromised cerebral circulation. The study will evaluate the physiological response to intrathoracic pressure regulation (IPR) therapy in hemodynamically stable patients with compromised cerebral circulation who are on ventilatory support.

Inclusion Criteria:

• ≥18 years of age
• intubated and mechanically ventilated on a volume controlled mode
• head injury or other intracranial pathology and compromised cerebral perfusion
• arterial line in place or alternative with continuous pressure monitoring
• SpO2 ≥90%
• mean arterial pressure >55
• admission to ICU or about to undergo neurosurgery with planned placement of an invasive intracranial pressure monitor
• inclusion presents no significant delays to planned emergent neurosurgery
• prior written informed consent

Exclusion Criteria:

• cardiac or pulmonary injury
• confirmed pneumothorax or hemothorax
• serious neck injury resulting in neck swelling with jugular venous compression
• evidence of ongoing uncontrolled bleeding
• respiratory disease such as COPD, interstitial lung disease, or other parenchymal or pulmonary vascular disease
• marked hypertension at time of device use defined as systolic blood pressure >180 mmHg
• congestive heart failure
• women with positive serum or urine pregnancy test or breast feeding

Duration of device use.