A Novel Active Humidifier for Noninvasively Ventilated Patients

Abstract

Background:

The RespirAq humidifier is an innovative heated humidifier that has been created to add humidity without the need for extra water. The humidifier rapidly transitions from a highly moisture-absorbent state to an extremely moisture-repellent form within milliseconds to capture moisture during exhalation and returning it during inspiration. This device provides 37°C / 95% relative humidity gas application suitable for individuals requiring humidification, including those patients who have undergone tracheostomies. Previous research has established that the device is compliant with EN ISO 80601–2–74:2020 during bench testing. In this research study, we aimed to compare the performance of the novel humidifier with a heated humidifier - HH (MR850 Fisher & Paykel Healthcare) and a heat and moisture exchanger - HME (DAR Covidien) in healthy volunteers during noninvasive ventilation (NIV) using a Simplus full face mask (Fisher & Paykel Healthcare).

Methods:

Ten healthy volunteers were recruited. NIV was performed at different settings (inspiratory positive airway pressure (IPAP) range 5-20 cm H₂O, expiratory positive airway pressure (EPAP) = 5 cm H₂O) over a 1-hr period. Humidity and temperature were collected continuously during the study. The study was approved by the Auckland University of Technology Ethics Committee.

Results:

Sixty per cent of participants were female. Mean age 35.6 ± 5.89 years (M ± SD, n = 10). Absolute humidity inside the face mask increased from 22.55 ± 2.41 mg/L without humidification to 30.18 ± 2.07 mg/L with an HME, and 39.09 ± 1.05 mg/L and 38.23 ± 1.78 mg/L when using a water-based heated humidifier and the novel humidifier, respectively. When comparing the performance of the humidification devices head-to-head, the two heated humidifiers significantly outperformed the HME(HME vs Novel = P < .001, HME vs HH = P < . 001) and there was no significant difference seen between the two active humidifiers (P = .20).

Conclusions:

Results show that the device meets the 33 mg/L absolute humidity established by the EN ISO80601–2–74:2020 standards and that there is no significant difference in performance compared to traditional heated humidification. This suggests that the novel device can deliver the performance of a heater humidifier at the size, reliability, and ease of use of a heat and moisture exchanger. Due to the mechanism of action, droplet/aerosol transmission of COVID–19 may also be mitigated. Further studies are warranted to confirm these findings.

Absolute Humidity - without supplemental humidification (grey bars), with an HME (green bars), with a water-based heated humidifier HH (black bars), and with the RespirAq™ Active Humidifier (blue bars) for each participant. The Red line indicates the minimum humidity levels a humidifier must reached as described in the ISO 80601-2-74 standard

Absolute Humidity comparison - Without supplemental humidification (grey bar), with an HME (green bar), with a water-based heated humidifier HH (black bar), and with the RespirAq™ Active Humidifier (blue bar)