Prof. Jan Bondeson wrote a book called Buried Alive (https://www.amazon.co.uk/Buried-Alive-Terrifying-History-Pri...). I have a copy. He concluded that almost all historical accounts of premature burial could be explained in other ways, or were unreliable. There were, however, a handful of confirmed cases of people being rescued from premature burial and removed from their grave, only to die shortly afterwards. Around 200 years ago in Germany, many deceased were placed in Leichenhäusen until decomposition started, to ensure they weren't prematurely buried. Not one person woke up.

Of course, for obvious reasons it's impossible to be sure nobody was buried alive, but if anyone was, the air supply in their coffin wouldn't last longer than about an hour.

Another book of interest is Buried Alive by Jan Bondeson (https://www.amazon.com/Buried-Alive-Terrifying-History-Prima...), which covers the steps that were taken to prevent premature interment, including the ways death was diagnosed.