G-LOC LTC William W. Pond, MD, FS Chief Aerospace Medicine

G-LOC: Importance  Important cause :  aircraft lost  Class C Mishaps  Decrease performance

G-LOC: Cause  Inadequate oxygen to the brain:  Caused by inadequate blood flow:  Caused by insufficient blood pressure toward the head to overcome G forces pushing/pulling blood away from the head

G-LOC: Heart, Brain, Eyes  Heart has high metabolic requirement and has static inflation pressure, but coronary artery flow is little affected by Gs.  Brain loses consciousness in hypoxia.  Eye loses vision, peripheral first.  Vision lost earlier than consciousness due to intraocular static pressure.  5-7 second reserve of oxygen

G-LOC: Effect on Eye  Decreased blood flow  Eye reacts first –Grayout –Tunnel Vision –Immediate return of function with restoration of blood flow

G-LOC: Effects on Brain  Brain stays “turned off” even after flow restored.  Absolute incapacitation seconds –(Range 5-30) –Dream like state –Unaware of environment  Relative incapacitation seconds –(Range 8-80) –May respond to “pull –up, pull-up” command

G-LOC: Recognition  May go unnoticed due to partial amnesia  Suspect for sudden loss of altitude  Tingling around mouth  Sense of dreaming  May recognize during debriefing  Never use visual symptoms to test your current G tolerance

G-LOC: Tolerance  Anti G Straining Maneuver  Anticipation of G-onset  Physical and psychological condition  G awareness  Combat Edge  Reclined Seat

G_LOC: Recognition (May occur unnoticed)