For how long is it safe for an infant to be "handbagged" in lieu of a life support machine?

One of my children was handbagged by ER staff and EMS Ambulance personnel for nearly two hours, and I'm just wondering if I should worry about brain damage from gaps in oxygen delivery???? The ER we went to didn't have a life support machine for infants, so they had to call another hospital to come get him as they were better equipped to deal with his needs. When the Ambulance arrived I found out he would be manually handbagged yet again en route to the other hospital. I looked on the net and can't find anything about a time limit on the safe use of the manual apparatus. If anyone knows, please answer, or maybe someone can direct me to a site with that information, as I can't seem to find it... Thanks!