text: The pressure inside each enclosed bubble will remain the same.  If the airline is pressurized, there's no effect (usually cargo planes are pressurized, except in extreme cases).  Physics dictates that the bubble would "appear" to EXPAND in the increasing altitude due to lower pressure outside/inside the plane; therefore if you are concerned about shipping something via altitude w/o pressurized cabin--- no worries.  It would take a trip outside of earth's atmosphere to pop... if no cabin pressurization.  Don't take it out scuba diving; water depth increases pressure exponentially, and would collapse them.