Endoscopic bite block

An endoscopic bite block, comprising:

• a tubular body comprising an inner end section for insertion into the mouth of a subject, an outer end section for insertion of an endoscopic probe, and a central channel, said tubular body having at least one breath sampling opening through the roof of said central channel, wherein said at least one breath sampling opening is adapted to receive at least part of an oral prong;
• a front plate connected to said outer end section of said tubular body;
• and
• a penetrable curtain attached to said outer end section across the majority of the internal cross section of said tubular body, wherein the penetrable curtain is configured to isolate cavity volume within the bite block and substantially prevent flow of gases across said majority of said cross section of said tubular body to substantially separate respired breath from ambient air in order to facilitate accurate capnographic sampling, wherein the penetrable curtain also being configured to provide a hole at an extremity of said curtain, close to the at least one breath sampling opening to allow the subject to breath ambient air during use when a medical instrument is inserted through the internal cross section of the tubular body.