Any experts out there? Got short called to do a Cabo turn out of CLT. Our planned route thru Mexico flies right thru the brown shaded area on the Depressurization Critical Terrain Chart. There are no notes on the release that indicate anything about depressurization planning required. The terrain column on our release showed no terrain higher than 9200 ft between waypoints. Then we got rerouted just as we entered mexican airspace. Now our release terrain numbers are useless and grid numbers on the high chart show terrain over 13000 ft in our general area of flight but we can't really determine if it is a factor or not. I messaged our dispatcher with the reroute and asked if it was terrain critical but no reply for 45 minutes. So we planned our escape routes. Good way to pass the time but we couldn't really tell if it was required.


Suggestions? Advice?