Current safety standards for commercial airplanes mandate that no single failure of the pressurization system can result in a loss of cabin pressure.

Modern airplanes can fly at altitudes above 40,000 feet. Certification to fly at these altitudes requires that no loss of pressure would result in the passengers being exposed to cabin altitudes above 40,000 feet for more than 1 minute. Similarly there is a long standing requirement that passengers not be exposed to cabin altitudes above 25,000 feet for more than two minutes.

This means that emergency descents must rapidly exceed 10,000 feet per minute (about 113 mph vertically). Assuming the pilots can maneuver aggressively enough to meet the regulatory requirements you would most likely pass out within 30 to 60 seconds and assuming no other injuries, you would regain consciousness after passing below 10,000 feet, say in 2 to 3 minutes. Not sure if this is enough time to cause significant damage other than from the rapid depressurization.

Even with 100% oxygen there is not enough pressure/density above 30,000 feet for most people to sustain consciousness. Pilot oxygen masks are sealed to maintain pressure. Passenger oxygen masks don't seal enough to maintain pressure but having a higher concentration of oxygen at even much lower pressures can help a lot.

-Eric