In a trial of 101 patients, we did not find any increase in the residual index with the V̇-Com added to the circuit. In addition, residual indexes are well known to be unreliable.9 In auto-titrating mode, the small pressure drop created by the V̇-Com may increase the P90% / P95% by the same amount and thus, there should be minimal or no change in the residual index. For patients on a fixed pressure PAP, there could be a small increase in residual index, but this can be avoided by increasing the fixed pressure by 0.5-1.0 cm H2O (the pressure drop of the exhaust flow). However, residual indexes are very unreliable9 and vary even based on the type of interface.8 In the April 2022 issue of JCSM, Ni and Thomas9 reported the difference between machine-detected REI and manually scored REI was 10.72+/-8.43 events/hour, which reminds us as clinicians to focus less on PAP device residual indexes and more on patients’ acceptance and response to therapy.