Physiological effects of various G-suit vs. positive pressure breathing ratios on +Gz tolerance

Positive acceleration in the head to toe direction (+Gz) causes a reduction in blood circulation to the head which adversely affects the central nervous system and causes a decrease in vision. It has been established that positive pressure breathing enhances +Gz tolerance by increasing head level blood pressure. Utilizing the NAWC centrifuge, eight subjects outfitted with Navy combat edge (NCE) protective systems were exposed to a series of +Gz rapid onset rate (ROR) profiles and positive pressure breathing schedules. Stroke volume (SV), heart rate (HR), and cardiac output (CO) were measured using a new impedance cardiograph (ICG), the Drexel patented IQ system. Blood pressure (BP), local blood volume using an infrared plethysmograph (IRP), respiratory rate, and peripheral light loss were also measured. These parameters were used to investigate potential alternate positive pressure breathing schedules to enhance the tactical pilots´ +Gz tolerance