A single V̇-Com in the circuit has little effect on the auto titration, particularly with patients who require lower pressures. With higher pressure settings and higher exhaust flow rates, P90% / P95% pressure may increase slightly, yet we did not find this in a trial of 101 patients. To minimize this possibility, always put V̇-Com into the PAP circuit with the PAP device off. Auto-titrating algorithms usually monitor the flow in the system initially to determine a baseline before titrating. If the V̇-Com device is already in the circuit when the device turns on, we have not found V̇-Com to significantly affect event detection in either Philips, ResMed, or React Health (formerly 3B) devices. V̇-Com could slightly increase the P90% / P95% in auto-titrating mode at high pressures. For example, with a circuit exhaust of 30 Lpm, V̇-Com will decrease the pressure on the patient side of the V̇-Com by 0.6 cmH2O between breaths. Therefore, the resulting P90% / P95% recorded by the PAP device may be 0.5 cmH2O higher, but the P90% / P95% experienced by the patient is unchanged. To further explore the circuit effects, we have tested combining two and even three V̇-Com devices in series, which doubles or triples the effect of V̇-Com, respectively (we are not recommending this for patients). With an exhaust flow of 30 Lpm, two V̇-Com devices in series would cause a pressure drop of 1.2 cmH2O (2 x 0.6 cmH2O). However, this pressure drop may not increase the P90% / P95%. For the P90% / P95% to increase, the patient must have events detected in which the PAP device algorithm responds with a pressure increase. During expiration, exhaust flow is mostly patient flow and flow across the V̇-Com is minimal with minimal pressure drop. This unique maintenance of EPAP by V̇-Com may prevent additional respiratory events and subsequent changes in P90% / P95%.