Evaluation of a Novel Dry Powder Surfactant Aerosol Delivery System for Use in Premature Infants Supported with Bubble CPAP

Aerosolized lung surfactant therapy during nasal continuous positive airway pressure (CPAP) support avoids intubation but is highly complex, with reported poor nebulizer efficiency and low pulmonary deposition. The study objective was to evaluate particle size, operational compatibility, and drug delivery efficiency with various nasal CPAP interfaces and gas humidity levels of a synthetic dry powder (DP) surfactant aerosol delivered by a low-flow aerosol chamber (LFAC) inhaler combined with bubble nasal CPAP (bCPAP). A particle impactor characterized DP surfactant aerosol particle size. Lung pressures and volumes were measured in a preterm infant nasal airway and lung model using LFAC flow injection into the bCPAP system with different nasal prongs. The LFAC was combined with bCPAP and a non-heated passover humidifier. DP surfactant mass deposition within the nasal airway and lung was quantified for different interfaces. Finally, surfactant aerosol therapy was investigated using select interfaces and bCPAP gas humidification by active heating. Surfactant aerosol particle size was 3.68 µm. Lung pressures and volumes were within an acceptable range for lung protection with LFAC actuation and bCPAP. Aerosol delivery of DP surfactant resulted in variable nasal airway (0-20%) and lung (0-40%) deposition. DP lung surfactant aerosols agglomerated in the prongs and nasal airways with significant reductions in lung delivery during active humidification of bCPAP gas. Our findings show high-efficiency delivery of small, synthetic DP surfactant particles without increasing the potential risk for lung injury during concurrent aerosol delivery and bCPAP with passive humidification. Specialized prongs adapted to minimize extrapulmonary aerosol losses and nasal deposition showed the greatest lung deposition. The use of heated, humidified bCPAP gases compromised drug delivery and safety. Safety and efficacy of DP aerosol delivery in preterm infants supported with bCPAP requires more research.

In vitro-in vivo correlation of aerosol deposition before and after metered-dose inhaler coaching in healthy children

Although pressurized metered dose inhaler (pMDI) education is a routine part of childhood asthma management and encouraging "optimal breathing patterns" (i.e., slowly, deeply, completely, and with a mouth seal on the mouthpiece) is an integral part of recommended pMDI education, there is currently no quantifiable way to determine if a child is inhaling their medication correctly or optimally through a valved holding chamber (VHC). The TipsHaler™ (tVHC) is a prototype VHC device that measures inspiratory time, flow, and volume without changing the properties of the medication aerosol. The measurements in vivo recorded by the tVHC can be downloaded and transferred to a spontaneous breathing lung model to simulate the inhalational patterns in vitro and also determine the deposition of inhaled aerosol mass with each pattern. We hypothesized that pediatric patients' inhalational patterns when using a pMDI would improve after active coaching via tVHC. This would increase the pulmonary deposition of inhaled aerosols in an in vitro model. To test this hypothesis, we conducted a single-site, prospective, pilot, pre-and-post intervention study paired with a bedside-to-bench experiment. Healthy, inhaler-naïve subjects used a placebo inhaler in conjunction with the tVHC before and after coaching and recorded inspiratory parameters. These recordings were then implemented into a spontaneous breathing lung model during albuterol MDI delivery, and pulmonary deposition of albuterol was quantified. In this pilot study, active coaching resulted in a statistically significant increase in inspiratory time (n = 8, p = 0.0344, 95%CI: 0.082 to ∞). tVHC recorded inspiratory parameters obtained from patients were successfully implemented in the in vitro model, which demonstrated that both inspiratory time (n = 8, r = 0.78, p < 0.001, 95%CI: 0.47 to 0.92) and volume (n = 8, r = 0.58, p = 0.0186, 95%CI: 0.15 to 0.85) strongly correlate with pulmonary deposition of inhaled drugs.

Assessment of mask efficiency for preventing transmission of airborne illness through aerosols and water vapor

Background: Currently the Center for Disease Control has advised the use of face coverings to prevent transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to those who are unvaccinated. This study seeks to evaluate if cloth masks have increased efficiency with the addition of a filter material. Methods: An adult airway and test lung model were exposed to nebulized ‘coarse’ aerosol droplets (0.5-11 µm) and humidified ‘fine’ water vapor particles (0.03-0.05 µm). Aerosol was quantified based on particles deposited on the face, airway and lung model. Tracheal humidity levels characterized fine particle permeability. Both phases of testing were conducted by evaluating the following testing conditions: 1) no mask; 2) cloth mask; 3) cloth mask with Swiffer™ filter; 4) cloth mask with Minimum Efficiency Reporting Value (MERV) 15 filter; 4) cloth mask with PM2.5 filter 5) surgical mask and 6) N95 respirator. Results: All mask conditions provided greater filtration from coarse particles when compared to no mask (P<0.05). All cloth mask with filter combinations were better at stopping fine particles in comparison to no mask. A cloth mask without a filter and surgical mask performed similarly to no mask with fine particles (P<0.05). The cloth mask with MERV 15 filter and the surgical mask performed similarly to the N95 with course particles, while the cloth mask with Swiffer™ performed similarly to the N95 with the fine particles (P<0.05). Conclusions: Respiratory viruses including SARS-CoV-2 and influenza are spread through exposure to respiratory secretions that are aerosolized by infected individuals. The findings from this study suggest that a mask can filter these potentially infectious airborne particles.

Physiologic Effects of Nasal Aspiration and Nasopharyngeal Suctioning on Infants With Viral Bronchiolitis

BACKGROUND

There is limited evidence supporting an optimum method for removing mucus from the airways of hospitalized infants with bronchiolitis. This study was designed to evaluate short-term physiologic effects between nasal aspiration and nasopharyngeal suctioning in infants.

METHODS

Sixteen infants requiring hospitalization for supportive management of bronchiolitis were instrumented with transcutaneously measured partial pressure of carbon dioxide ([Formula: see text]) and [Formula: see text] monitoring. Electrical impedance tomography (EIT) was used to estimate changes in inspiratory and end-expiratory lung volume loss and recovery. Subjects were suctioned with both nasal aspiration and nasopharyngeal suctioning methods in a randomized order (8 received nasal aspiration followed by nasopharyngeal suctioning, and 8 received nasophayrgeal suctioning followed by nasal aspiration). Noninvasive gas exchange and EIT measurements were obtained at baseline (pre-suction) and at 10, 20, and 30 min following each suctioning intervention. Sputum mass was obtained following suctioning, and clinical respiratory severity scores, before and after suctioning, were computed.

RESULTS

There were no differences in inspiratory EIT (P = .93), change in end-expiratory lung impedance (ΔEELI; P = .53), [Formula: see text] (P = .41), [Formula: see text] (P = .88), heart rate (P = .31), or breathing frequency (P = .15) over the course of suctioning between nasal aspiration and nasopharyngeal suctioning. Sputum mass (P = .14) and clinical respiratory score differences before and after suctioning (P = .59) were not different between the 2 suctioning interventions. Sputum mass was not associated with ΔEELI at 30 min for nasal aspiration (ρ = 0.11, P = .69), but there was a moderate positive association for nasopharyngeal suctioning (ρ = 0.50, P = .048).

CONCLUSIONS

Infants with viral bronchiolitis appeared to tolerate both suctioning techniques without adverse short-term physiologic effects, as indicated by the unchanged gas exchange and estimated lung volumes (EIT). Nasopharyngeal suctioning recovered 36% more sputum than did nasal aspiration and there was moderate correlation between sputum mass and end-expiratory lung impedance change at 30 minutes post-suction with nasopharyngeal that was not present with nasal aspiration. It is possible that a subset of patients may benefit from one type of suctioning over another. Future research focusing on important outcomes for suctioning patients with bronchiolitis with varying degrees of lung disease severity is needed.