An overview of the physiological effects of sustained high +Gz forces on human being

In the search for the advantage in aerial combat, increasingly higher performance aircraft are being developed that impose ever greater acceleration force loads on the human pilot. The symptomatology associated with increasing +Gz acceleration forces, culminating in G-induced loss of consciousness caused by the cessation of cerebral blood circulation are described. The inability of the normal cardiovascular system mechanisms to provide adequate circulation to the brain and the eyes, and the resulting associated symptomatology and physiological changes are discussed. The normal weight, hydrostatic pressure and physiological ventilation/perfusion gradients in the lungs are exaggerated under high +Gz forces resulting in increased pulmonary arterio-venous shunting. This causes impairment of circulatory oxygenation and may also result in acceleration induced atelectasis. The effects of +Gz acceleration forces on the renal system and the limitations of the cervical musculature are also discussed. This paper serves to describe the human physiological responses to increased +Gz acceleration forces in an attempt to provide a better understanding of the body's reaction to such demanding physical stressors.