A system includes a guidance device that provides feedback to a user to compress a patient's chest at a rate of between about 90 and 110 compressions per minute and at a depth of between about 4.5 centimeters to about 6 centimeters. The system includes a pressure regulation system having a pressure-responsive valve that is configured to be coupled to a patient's airway. The pressure-responsive valve is configured to remain closed during successive chest compressions in order to permit removal at least about 200 ml from the lungs in order to lower intracranial pressure to improve survival with favorable neurological function. The pressure-responsive valve is configured to remain closed until the negative pressure within the patient's airway reaches about −7 cm H2O, at which time the pressure-responsive valve is configured to open to provide respiratory gases to flow to the lungs through the pressure-responsive valve.