Effect of Intrathoracic Pressure Regulation on Decreased Cerebral Perfusion (4hour)

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