• A user with chronic respiratory failure, high ambient CO2 and respiratory acidosis. In this situation effective removal of the CO2 respiratory drive could cause breathlessness and panic.
• A user with low tidal volume (shallow breathing) compared with the dead space of the R2D. In this case there would be ineffective CO2 removal.
• Any air leaks in the canister seals, face mask or counter lung. • Any damage or contamination of the scrubber. • Anxiety precipitated panic attack by the user with associated breath holding.
The successful use of the R2D DeBreather is technique depend- ent. The ability to practice fitting and using the device with the scrubber removed and the counter-lung open to the air, would also be particularly useful.