Effects of flow on carbon dioxide washout and nasal airway pressure in healthy adult volunteers during the constant-flow mode in a non-invasive ventilator

RationaleDelivery of continuous positive airway pressure (CPAP) is the standard treatment for obstructive sleep apnea (OSA) in children and adults. Treatment adherence is a major challenge as many patients find the CPAP mask uncomfortable. The study aim was to demonstrate the feasibility of delivered CPAP through customised nasal masks by assessing mask leak and comfort of customised masks compared to commercially available CPAP masks.MethodsSix healthy adult volunteers participated in a cross-over study including commercial masks in three different sizes (petite, small/medium, and large) from the same supplier and a customised mask fabricated for each subject using 3D facial scanning and modern additive manufacturing processes. Mask leak and comfort were assessed with varying CPAP levels and mask tightness. Leak was measured in real time using an inline low-resistance Pitot tube flow sensor, and each mask was ranked for comfort by the subjects.ResultsMask leak rates varied directly with CPAP level and inversely with mask tightness. When ranked for comfort, three subjects favoured the customised mask while three favoured a commercial mask. The petite mask yielded the highest mask leaks and was ranked least comfortable by all subjects. Relative mask leaks and comfort rankings for the other commercial and customised masks varied between individuals. Mask leak was comparable when comparing the customised masks with the highest ranked commercial masks.ConclusionCustomised masks successfully delivered target CPAP settings in all six subjects, demonstrating the feasibility of this approach.

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Topical active H1-antihistamines and their effect on nasal airway resistance

The Journal of Laryngology & Otology ◽

10.1017/s0022215100131469 ◽

1995 ◽

Vol 109 (9) ◽

pp. 841-843

Author(s):

R. J. van Houten ◽

D. J. Premachandra

Keyword(s):

Nasal Spray ◽

Airway Resistance ◽

Healthy Adult ◽

Nasal Airway ◽

Subjective Improvement ◽

Airway Patency ◽

Subjective Change ◽

Nasal Airway Resistance ◽

H1 Antihistamines ◽

Adult Volunteers

AbstractThe introduction of a topically active H1-antihistamine nasal spray Azelastine, has given an extra dimension in the management of allergic rhinits. The drug acts rapidly and avoids the sustemic adverse effects of antihistimines. An objective prospective study was performed to detect the effect of Azelastine nasal spray on nasal airway resistance. Twelve healthy adult volunteers with no rhinological problems were included in the study. Nasal cavites were sprayed with 280 μg (two puffs) of Azelastine nasal spray and the nasal airway resistance was measured with anterior rhinomanometry at intervals of 30 minutes for up to two hours. Our study has shown statistically significant increase in the total nasal airway resistance following the use orf Azelastine nasal spray in the absence of a subjective change in nasal airway resistance. There are substances when inhaled which can cause subjective improvement in nasal airway patency without changing the measured nasal airway resistance. However this medication gives no subjective change in nasal airway patency in spite of increasing nasal airway resistance.

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Role of the Nasal Airway in Regulation of Airway Resistance During Hypercapnia and Exercise Second-Place Resident Award at 1982 Research Forum

Otolaryngology ◽

10.1177/019459988409200311 ◽

1984 ◽

Vol 92 (3) ◽

pp. 302-307 ◽

Cited By ~ 9

Author(s):

Janet S. Mertz ◽

Thomas V. Mccaffrey ◽

Eugene B. Kern

Keyword(s):

Airway Resistance ◽

Healthy Adult ◽

Minute Ventilation ◽

Respiratory Center ◽

Nasal Airway ◽

Nasal Resistance ◽

Adult Volunteers

Posterior mask rhinomanometry was used to measure nasal resistance during exercise and hypercapnia in 10 healthy adult volunteers. Exercise was produced by peddling a stationary bicycle at three loads. Hypercapnia was produced by breathing O2 mixtures containing 5%, 6%, and 8% CO2. The results showed that (1) nasal resistance decreases linearly as expired CO2 levels and exercise levels increase, (2) minute ventilation increases linearly as expired CO2 levels and exercise levels increase, and (3) nasal resistance varies inversely with minute ventilation during both hypercapnia and exercise. The constant relationship between nasal resistance and minute ventilation during hypercapnia and exercise suggests that nasal resistance is regulated by the respiratory center to match the level of respiratory demand.

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CONSTANT-FLOW MODE OF NON-INVASIVE VENTILATOR IN HEALTHY ADULTS: VALIDATION OF MECHANISMS OF ACTION

CHEST Journal ◽

10.1016/j.chest.2020.05.469 ◽

2020 ◽

Vol 157 (6) ◽

pp. A419

Author(s):

Y. Juanjuan ◽

M. Dedong

Keyword(s):

Mechanisms Of Action ◽

Healthy Adults ◽

Flow Mode ◽

Constant Flow ◽

Non Invasive

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The comfort assessment in healthy adults during constant‐flow mode in non‐invasive ventilator

The Clinical Respiratory Journal ◽

10.1111/crj.13459 ◽

2021 ◽

Author(s):

Juanjuan Yao ◽

Wei Li ◽

Mengmeng Peng ◽

Kaixin He ◽

Dedong Ma ◽

...

Keyword(s):

Healthy Adults ◽

Flow Mode ◽

Constant Flow ◽

Non Invasive

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Comparison of airway pressures and expired gas washout for nasal high flow versus CPAP in child airway replicas

Respiratory Research ◽

10.1186/s12931-021-01880-z ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Kelvin Duong ◽

Michelle Noga ◽

Joanna E. MacLean ◽

Warren H. Finlay ◽

Andrew R. Martin

Keyword(s):

Carbon Dioxide ◽

Airway Pressure ◽

High Flow ◽

Nasal Airway ◽

Lung Simulator ◽

Airway Pressures ◽

Obstructive Sleep ◽

Tracheal Pressure ◽

Expired Gas ◽

End Tidal

Abstract Background For children and adults, the standard treatment for obstructive sleep apnea is the delivery of continuous positive airway pressure (CPAP). Though effective, CPAP masks can be uncomfortable to patients, contributing to adherence concerns. Recently, nasal high flow (NHF) therapy has been investigated as an alternative, especially in CPAP-intolerant children. The present study aimed to compare and contrast the positive airway pressures and expired gas washout generated by NHF versus CPAP in child nasal airway replicas. Methods NHF therapy was investigated at a flow rate of 20 L/min and compared to CPAP at 5 cmH2O and 10 cmH2O for 10 nasal airway replicas, built from computed tomography scans of children aged 4–8 years. NHF was delivered with three different high flow nasal cannula models provided by the same manufacturer, and CPAP was delivered with a sealed nasal mask. Tidal breathing through each replica was imposed using a lung simulator, and airway pressure at the trachea was recorded over time. For expired gas washout measurements, carbon dioxide was injected at the lung simulator, and end-tidal carbon dioxide (EtCO2) was measured at the trachea. Changes in EtCO2 compared to baseline values (no intervention) were assessed. Results NHF therapy generated an average positive end-expiratory pressure (PEEP) of 5.17 ± 2.09 cmH2O (mean ± SD, n = 10), similar to PEEP of 4.95 ± 0.03 cmH2O generated by nominally 5 cmH2O CPAP. Variation in tracheal pressure was higher between airway replicas for NHF compared to CPAP. EtCO2 decreased from baseline during administration of NHF, whereas it increased during CPAP. No statistical difference in tracheal pressure nor EtCO2 was found between the three high flow nasal cannulas. Conclusion In child airway replicas, NHF at 20 L/min generated average PEEP similar to CPAP at 5 cm H2O. Variation in tracheal pressure was higher between airway replicas for NHF than for CPAP. The delivery of NHF yielded expired gas washout, whereas CPAP impeded expired gas washout due to the increased dead space of the sealed mask.

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