Abstract
BACKGROUND: The present study tested a novel nebulizer and circuit that use breath enhancement and breath actuation to minimize ventilator influences. The unique circuit design incorporates “wet-side” jet nebulization (the nebulizer connected to the humidifier outlet port) to prevent unpredictable aerosol losses with active humidification. The system was studied using several ventilator brands over a wide range of settings, with and without humidification.
METHODS: During treatment, a 2-position valve directed all ventilator flow to the nebulizer, providing breath enhancement during inspiration. Aerosol was generated by air 50 psi 3.5 L/m triggered during inspiration by a pressure-sensitive circuit. Particles were captured on an inhaled mass filter. Testing was performed by using active humidification or bypassable valved heat and moisture exchanger (HME) over a range of breathing patterns, ventilator modes, and bias flows (0.5-5.0 L/m). The nebulizer was charged with 6 mL of radiolabeled saline solution. Mass balance was performed by using a gamma camera. Tidal volume was monitored by ventilator volume (exhaled VT) and test lung volume. The Mann-Whitney test was used.
RESULTS: A total of 6 mL was nebulized within 1 h. Inhaled mass (% neb charge): mean ± SD (all data) 31.1% ± 6.45; no. = 83. Small significant differences were seen with humidification for all modes (humidified 36.1% ± 5.60, no. = 26; bypassable valved HME 28.8% ± 5.51, no. = 57 [P < .001]), continuous mandatory ventilation modes [P < .001], and pressure support airway pressure release ventilation modes [P < .001]. Mass median aerodynamic diameter ranged from 1.04 to 1.34 μm. The VT was unaffected (exhaled VT –5.0 ± 12.9 mL; P = .75) and test lung (test lung volume 25 ± 14.5 mL; P = .13). Bias flow and PEEP had no effect.
CONCLUSIONS: Breath enhancement with breath actuation provided a predictable dose at any ventilator setting or type of humidification. Preservation of drug delivery during active humidification is a new finding, compared with previous studies. The use of wall gases and stand alone breath actuation standardizes conditions that drive the nebulizer independent of ventilator design. Wet-side nebulizer placement at the humidifier outlet allows delivery without introducing aerosol into the humidification chamber.
- aerosols
- nebulizers and vaporizers
- administration
- inhalation
- ventilators
- mechanical
- humidifiers
- drug delivery
- bias flow
Footnotes
- Correspondence: Ann D Cuccia MPH RRT, Stony Brook University Respiratory Care Program, School of Health Technology and Management, HSC Level 2, Room 412, Stony Brook, NY 11794-8203. E-mail: ann.cuccia{at}stonybrook.edu
The study location was the Aerosol Laboratory, Division of Pulmonary, Critical Care and Sleep Medicine, Stony Brook University Medical Center, Stony Brook, New York.
The study was supported in part by InspiRx, The State University of New York at Stony Brook holds patents in the fields of nebulizer development and antibiotic delivery, which have been licensed to InspiRx.
Dr Smaldone and Ms Cuccia disclose relationships with InspiRx. The other authors have disclosed no conflicts of interest.
Dr Ashraf presented a version of this paper at the 22nd International Society for Aerosols in Medicine Congress, held May 25–29, 2019 in Montreux, Switzerland; by Ms Cuccia at the Stony Brook University 13th Annual Women in Medicine Conference, held March 6, 2019 in Stony Brook, New York; and by Ms Cuccia at the AARC Congress 2018, held December 4–7, 2018 in Las Vegas, Nevada.
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