CPAP comfort
that doesn’t
compromise therapy.

V-ComTM is engineered to provide comfort without compromising therapy. V-ComTM lowers inspiratory pressure and peak inspiratory flow rate but has minimal to no effect on EPAP. By stabilizing the airway during exhalation with EPAP, inspiratory obstruction can be avoided.² Hypoglossal nerve stimulators utilize this same principal by beginning stimulation during expiration.

At very high PAP settings where exhaust flow is higher than peak expiratory flow there will still be some circuit flow over the V-ComTM during exhalation and EPAP will decrease slightly. Certainly, by maintaining the EPAP, V-ComTM provides much better therapy than the alternative of reducing pressure settings.

In a small trial of 101 patients (63 on the ResMed AirSense 11, 21 on Philips Dream Station 2, 17 on React Health Luna 2) experiencing 4 nights without V-ComTM and 4 nights with the V-ComTM, the auto-titrated pressure (P95% / P90% pressure) was unchanged (11.5 vs 11.7 cmH₂O). The residual index decreased slightly but with statistical significance (p-value 0.001) (1.5 vs 1.8 events/hour), and there was significantly less leak with V-ComTM in the circuit (p value = <0.001). Thus, the V-ComTM did not decrease therapy and may improve the experience by decreasing leak.

While performing manual titration during polysomnography in 20 patients, once patients appeared to reach their therapeutic pressure, a V-ComTM was added to the circuit. The average pressure increase was 1.2 cmH₂O and that was as expected principally at higher pressures where the higher exhaust flow can affect EPAP. It is also very possible by the design that some patients were possibly incompletely titrated before the V-ComTM was added.

Is “therapy” simply the maintenance of the set pressure? It is important to understand that PAP devices are designed to deliver a set pressure to the face (nose and/or mouth). This set pressure may not translate to the pharynx or lungs. The nasal valve has variable resistance depending on its anatomy and degree of congestion and can create considerable pressure drop on inspiration, affecting pharyngeal/lung pressure from nasal masks or nasal breathing on an oronasal mask. Yet, despite this pressure drop, nasal masks have been shown to require less pressure than an oronasal mask.⁶⁻⁸

In addition, different interfaces have different resistances, particularly nasal pillow interfaces, which can create additional pressure drop. PAP manufacturers have attempted to account for this to some degree, but this is clearly made worse by interchanging equipment from different manufacturers. Thus, even changing the interface can affect therapy.

Breathing nasally on PAP has a totally different physiology than breathing orally. While breathing nasally drops inspiratory pressure, expiratory pressure increases because of the nasal resistance. For a nasal pillow mask, the added resistance in the pillow cushion further increases the “back” pressure or EPAP, a small cushion tremendously more than the large cushion. This is why nasal masks require less pressure to eradicate the respiratory events.

Defining “therapy” as delivering a determined pressure to the face may be an incomplete approach. The “delivered” pressure is irrelevant in a non-adherent patient. Therapy requires usage, and by increasing comfort and tolerance then long-term adherence may increase.

A single V-ComTM 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 V-ComTM 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 V-ComTM device is already in the circuit when the device turns on, we have not found V-ComTM to significantly affect event detection in either Philips, ResMed, or React Health (formerly 3B) devices.

V-ComTM could slightly increase the P90% / P95% in auto-titrating mode at high pressures. For example, with a circuit exhaust of 30 Lpm, V-ComTM will decrease the pressure on the patient side of the V-ComTM 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 V-ComTM devices in series, which doubles or triples the effect of V-ComTM, respectively (we are not recommending this for patients). With an exhaust flow of 30 Lpm, two V-ComTM 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 V-ComTM is minimal with minimal pressure drop. This unique maintenance of EPAP by V-ComTM may prevent additional respiratory events and subsequent changes in P90% / P95%.

In summary, no. Obviously, a set fraction of inspired O₂ (FiO₂) delivered from a high flow O₂ source into the PAP device is unaffected by the presence of V-ComTM in the circuit. We tested bleeding O₂ at 2 Lpm into a full-face mask and into the circuit between the circuit hose and nasal mask tube with and without the V-ComTM in the circuit. In both PAP circuits the FiO₂ increased by 0.5-1%. This was expected as the inspiratory pressure drop decreases exhaust flow and less O₂ is lost in the circuit during inspiration. Again, the change is minimal.

For patients who have been prescribed a fixed pressure on a PAP device and have a V-ComTM device added to the circuit, a clinician may consider increasing the set fixed pressure by the pressure drop of the exhaust flow (found in the package insert of the interface). For example, if the exhaust flow of the patient’s mask is 30 Lpm at the fixed pressure, V-ComTM may decrease patient pressure by 0.6 cm H₂O between breaths. The clinician may wish to increase the fixed pressure by 0.5-1.0 cm H₂O or just observe and follow.

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