List of works
Journal article
Asthma and depression in older American adults: An analysis of Medicare recipients
First online publication 12/05/2025
Respiratory Care, online ahead of print
Background: Individuals with asthma are disproportionately affected by depression relative to those without asthma. However, this relationship in those ≥65 years of age with asthma remains unclear. This study aims to determine the association between asthma and depression in individuals aged ≥65 receiving Medicare support. Methods: A pooled cross-sectional analysis of Medicare Current Beneficiary Survey data examined the association between asthma and depression from 2018 to 2020. Depression was defined as a score of ≥10 from the Patient Health Questionnaire-9. Disease-related variables were recorded if the subject met Medicare claims criteria for the calendar year regardless of sufficient fee-for-service coverage. Adjusted regression models were developed to determine the association between prevalent asthma, comorbidities, gender, area deprivation index, and depression. Results: Among 31,064 individuals available for analysis, the weighted prevalence of depression in subjects with asthma was 38.6%. The adjusted regression model indicated that asthma was not independently associated with depression in this population (odds ratio (OR) = 1.18, 95% confidence interval (CI) [0.96–1.45]). Subjects with asthma and anxiety (OR = 1.11, 95% CI [1.06–1.16]), cardiovascular disease (OR = 1.24, 95% confidence interval (CI) [1.15–1.32]), or diabetes (OR = 1.30, 95% CI [1.24–1.36]) were more likely to report concomitant depression. Women ≥65 years of age with asthma had greater odds of reporting depression compared to men with asthma (OR = 1.09, 95% CI [1.06–1.12]). Conclusions: Based on our findings, in older adults in the United States, asthma is not independently associated with greater odds of depression when compared to those without asthma.
Journal article
Management of Body Temperature via the Respiratory Tract
First online publication 08/25/2025
Respiratory care, online ahead of print
Hypothermia, defined as a core body temperature <= 35 degrees C, significantly increases morbidity and mortality in mechanically ventilated patients across numerous care settings. Physiologically, the upper airway conditions inspired gases to body temperature and humidity, minimizing heat energy loss and preventing mucosal damage. Instrumentation, such as endotracheal intubation, bypasses this natural mechanism, leading to considerable heat and moisture loss, potentially exacerbating hypothermia risks in critically ill patients. Active humidifiers and heat and moisture exchangers represent common strategies to mitigate airway heat loss, yet their effectiveness as a method to assist in whole-body rewarming is controversial. Emerging technologies indicate renewed interest in airway-based warming devices, especially for prehospital and military trauma scenarios, but robust clinical validation remains necessary. This narrative review evaluates the feasibility and effectiveness of airway-based thermoregulation through inhalation of heated, humidified gases.
Journal article
2024 Year in Review: Ventilator-Associated Pneumonia
Published 08/2025
Respiratory care, 70, 8, 1045 - 1052
Mechanical ventilation is essential for supporting critically ill patients but increases the risk of bacterial colonization resulting from instrumental, biological, and practice-related factors. Ventilator-associated pneumonia (VAP), a common complication, is linked to prolonged mechanical ventilation and poor outcomes. Although decades of research have emphasized prevention through care bundles and best practices, VAP remains a significant concern. This review highlights current evidence and emerging strategies for VAP prevention and management in 2024, with practical relevance for respiratory therapists caring for mechanically ventilated adult patients.
Journal article
Acute Effect of E-Cigarette Inhalation on Mucociliary Clearance in E-Cigarette Users
Published 08/2024
Journal of aerosol medicine and pulmonary drug delivery, 37, 4, 167 - 170
Recent studies show e-cigarette (EC) users have increased rates of chronic bronchitic symptoms that may be associated with depressed mucociliary clearance (MCC). Little is known about the acute or chronic effects of EC inhalation on in vivo MCC.
MCC was measured in young adult vapers (n = 5 males, mean age = 21) after controlled inhalation of a radiolabeled (Tc99m sulfur colloid) aerosol. Whole-lung clearance of radiolabeled deposited particles was measured over a 90-minute period for baseline MCC and associated with controlled periodic vaping over the first 60 minutes of MCC measurements. The vaping challenge was administered from a fourth generation box mod EC containing unflavored e-liquid (65% propylene glycol/35% vegetable glycerin, 3 mg/mL freebase nicotine). The challenge was administered at the start of each 10-minute interval of MCC measurements and consisted of 1 puff every 30 seconds for 5 minutes (i.e., 10 puffs for each 10-minute period for a total of 60 puffs during the initial 60 minutes of MCC measurements).
Compared with baseline, peripheral lung average clearance (%) over the 90 minutes of MCC measures was enhanced, associated with EC challenge, 12 (±6) versus 24 (±6), respectively (p < 0.05 by Wilcoxon signed-rank test).
Acute enhancement of in vivo MCC during EC challenge is contrary to recent studies showing nicotine-associated slowing of ciliary beat and mucus transport at higher nicotine levels than those used here. However, our findings are consistent with an acute increase in fluid volume and mucin secretion to the bronchial airway surface that is likely short lived.
Journal article
Published 2024
European respiratory review, 33, 171, 230223
Background: During neonatal and paediatric high-flow nasal cannula therapy, optimising the flow setting is crucial for favourable physiological and clinical outcomes. However, considerable variability exists in clinical practice regarding initial flows and subsequent adjustments for these patients. Our review aimed to summarise the impact of various flows during high-flow nasal cannula treatment in neonates and children.
Methods: Two investigators independently searched PubMed, Embase, Web of Science, Scopus and Cochrane for in vitro and in vivo studies published in English before 30 April 2023. Studies enrolling adults (≥18 years) or those using a single flow setting were excluded. Data extraction and risk of bias assessments were performed independently by two investigators. The study protocol was prospectively registered with PROSPERO (CRD42022345419).
Results: 38 406 studies were identified, with 44 included. In vitro studies explored flow settings’ effects on airway pressures, humidity and carbon dioxide clearance; all were flow-dependent. Observational clinical studies consistently reported that higher flows led to increased pharyngeal pressure and potentially increased intrathoracic airway pressure (especially among neonates), improved oxygenation, and reduced respiratory rate and work of breathing up to a certain threshold. Three randomised controlled trials found no significant differences in treatment failure among different flow settings. Flow impacts exhibited significant heterogeneity among different patients.
Conclusion: Individualising flow settings in neonates and young children requires consideration of the patient's peak inspiratory flow, respiratory rate, heart rate, tolerance, work of breathing and lung aeration for optimal care.
Journal article
Biomarkers of Airway Immune Homeostasis Differ Significantly with Generation of E-Cigarettes
Published 11/15/2022
American journal of respiratory and critical care medicine, 206, 10, 1248 - 1258
Rationale : Numerous studies have demonstrated that e-cigarettes can impact respiratory immune homeostasis; however, the extent of these effects remains an active area of investigation, and most previous studies were conducted with model systems or subjects exposed to third-generation e-cigarettes, such as vape pens and box mods.
Objectives : Given the rise in popularity of nicotine-salt–containing pods and disposable e-cigarettes (fourth generation), we set out to better understand the respiratory effects of these newer e-cigarettes and compare their effects to early-generation devices.
Methods : We collected induced sputum samples from a cohort of nonsmokers, smokers, third-generation e-cigarette users, and fourth-generation e-cigarette users (n = 20–30 per group) and evaluated the cellular and fluid-phase composition for markers of inflammation, host defense, and lung injury.
Measurements and Main Results : Fourth-generation e-cigarette users had significantly more bronchial epithelial cells in the sputum, suggestive of airway injury. Concentrations of soluble intercellular adhesion molecule 1 (sICAM1) and soluble vascular cell adhesion molecule 1 (sVCAM1) were significantly lower in fourth-generation e-cigarette users in comparison with all other groups, and CRP (C-reactive protein), IFN-γ, MCP-1 (monocyte chemoattractant protein-1), MMP-2 (matrix metalloproteinase 2), uteroglobin, and VEGF (vascular endothelial growth factor) were significantly lower in fourth- versus third-generation e-cigarette users, suggestive of overall immune suppression in fourth-generation e-cigarette users. Predictive modeling also demonstrated clear separation between exposure groups, indicating that the overall mediator milieu is different between groups, particularly fourth-generation e-cigarette users.
Conclusions : Our results indicate disrupted immune homeostasis in fourth-generation e-cigarette users and demonstrate that the biological effects of fourth-generation e-cigarette use are unique compared with those associated with previous-generation e-cigarettes.
Journal article
Published 10/2022
Respiratory care, 67, 10, 1217 - 1225
Little is known about the fate of expelled viral particulates during the aerosolization of inhaled medications during mechanical ventilation. We hypothesized that breathing patterns that generate a greater degree of shear stress and turbulent air flow will produce a greater concentration of exhaled viral RNA with the presence of a nebulizer during mechanical ventilation.
Eight ex vivo pig lungs were utilized as the physiological model. Each lung was dedicated to a specific breathing pattern that consisted of tidal breathing, respiratory distress, cough, and sneeze. Breath simulations were carried out through a commercial mechanical ventilator. Ninety mL of a bacteriophage stock at a concentration of 10
PFU/mL were introduced into the lungs during a 10-min sample collection session. The number of viral particles collected in exhalate was measured using quantitative polymerase chain reaction. The impact of breathing pattern on measured viruses was analyzed through two-way analysis of variance.
The interaction effect between nebulization and breath pattern on exhaled viral quantity was not statistically significant
= .80, partial η
= 0.167. The analysis of the main effects indicated that the effects of the breathing pattern and nebulization phase were not statistically significant
= .26, partial η
= 0.519;
= .98, partial η
= 0, respectively. There were no statistically significant differences among the breathing patterns related to measurable viral RNA. Coughing produced the most measurable increase in measured viral quantity during the nebulization phase and non-nebulization phase with a mean exhaled viral quantity (3.5 × 10
ng/μL [95% CI 1.6 × 10
-5.5 × 10
] and 2.7 × 10
ng/μL [95% CI 7.1 × 10
-5.5 × 10
], respectively). Tidal breathing with the presence of a nebulizer and respiratory distress without a nebulizer produced the lowest measured viral quantities (
= 1.1 × 10
ng/μL [95% CI -1.7 × 10
to 3.9 × 10
];
= 1.2 × 10
ng/μL [95% CI -1.6 × 10
to 4.0 × 10
]).
In this ex vivo porcine model, the introduction of a nebulizer did not increase the mean viral RNA captured throughout all of the breathing patterns.
Journal article
Validation of an app-based portable spirometer in adolescents with asthma
Published 04/01/2021
The Journal of asthma, 58, 4, 497 - 504
Objectives
Objective measurements of asthma impairment could aid teens in recognition of changes in asthma status over time. Ready access to a conventional spirometer is not realistic outside of the clinical setting. In this proof-of-concept study, we compared the performance of the VitalFlo mobile spirometer to the nSpire KoKo® sx1000 spirometer for accuracy in measuring Forced Expiratory Volume in one second (FEV1) and Forced Vital Capacity (FVC) in adolescents with asthma.
Methods
Two hundred forty pulmonary function measurements were collected from 48 adolescents with persistent asthma from the University of North Carolina’s pediatric allergy and pulmonology subspecialty clinics. Participants performed spirometry with the nSpireKoKo® sx1000 spirometer and the VitalFlo spirometer during their clinic visits. 119 simulated FVC maneuvers were conducted on both devices to standardize measurements. Pearson correlations, Bland-Altman procedure, and two-sample comparison tests were performed to assess the relationship between the two spirometers.
Results
VitalFlo measurements were significantly highly correlated with nSpireKoKo® spirometer values for FEV1, (r2=0.721, [95% CI, 0.749 ± 0.120], P < 0.001) and moderately for FVC (r2= 0.617, [95% CI, 0.640 ± 0.130], P < 0.001) measurements. There were no statistically significant differences of the mean FEV1 (M = 0.00764, SD = 0.364, t(59)=0.16, P = 0.87) and FVC measurements (M = 0.00261, SD = 0.565, t(59)=0.036, P = 0.97.) between the VitalFlo and nSpireKoKo® systems. Both devices demonstrated significantly high correlation when comparing the automated FVC (r2 = 0.997, [95% CI, 1.00 ± 0.00974], P < 0.001) measurements. Bland-Altman plots did not demonstrate significant bias between devices for both FEV1 (0.00764 L) and FVC (0.00261 L) measurements.
Conclusions
Lung function measurements from the VitalFlo mobile spirometer were comparable to a commercially-available spirometer commonly used in clinical settings. This validated app-based spirometer for home use has the potential to improve asthma self-management.
Journal article
Danger in the vapor?: ECMO for adolescents with status asthmaticus after vaping
Published 11/01/2020
Journal of Asthma, 57, 11, 1168 - 1172
Introduction: Electronic nicotine delivery systems (ENDS) use is on the rise in the adolescent and young adult populations, especially in the wake of sweet flavored ENDS solutions and youth-targeted marketing. While the extent of effect of ENDS use and aerosolized flavorings on airway epithelium is not known, there remains significant concern that use of ENDS adversely affects airway epithelial function, particularly in populations with asthma.
Case Study: In this case series, we review two cases of adolescents with history of recent and past ENDS use and asthma who required veno-venous extracorporeal membrane oxygenation (VV-ECMO) for status asthmaticus in the year 2018.
Results: Both patients experienced hypercarbic respiratory failure requiring VV-ECMO secondary to their status asthmaticus, with slow recovery on extensive bronchodilator and steroid regimens. They both recovered back to respiratory baseline and were counseled extensively on cessation of ENDS use.
Conclusion: While direct causation by exposure to ENDS cannot be determined, exposure likely contributed to symptoms. Based on the severity of these cases and their potential relationship with ENDS use, we advocate for increased physician screening of adolescents for ENDS use, patient and parent education on the risks of use, and family cessation counseling.