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Nasal high flow clears anatomical dead space in upper airway models.

Möller W, Celik G, Feng S, Bartenstein P, Meyer G, Oliver E, Schmid O, Tatkov S - J. Appl. Physiol. (2015)

Bottom Line: There was a similar tracer-gas clearance characteristic in the tube model and the upper airway model: clearance half-times were below 1.0 s and decreased with increasing NHF rates.The level of clearance in the nasal cavities increased by 1.8 ml/s for every 1.0 l/min increase in the rate of NHF.The study has demonstrated the fast-occurring clearance of nasal cavities by NHF therapy, which is capable of reducing of dead space rebreathing.

View Article: PubMed Central - PubMed

ABSTRACT
Recent studies showed that nasal high flow (NHF) with or without supplemental oxygen can assist ventilation of patients with chronic respiratory and sleep disorders. The hypothesis of this study was to test whether NHF can clear dead space in two different models of the upper nasal airways. The first was a simple tube model consisting of a nozzle to simulate the nasal valve area, connected to a cylindrical tube to simulate the nasal cavity. The second was a more complex anatomically representative upper airway model, constructed from segmented CT-scan images of a healthy volunteer. After filling the models with tracer gases, NHF was delivered at rates of 15, 30, and 45 l/min. The tracer gas clearance was determined using dynamic infrared CO2 spectroscopy and 81mKr-gas radioactive gamma camera imaging. There was a similar tracer-gas clearance characteristic in the tube model and the upper airway model: clearance half-times were below 1.0 s and decreased with increasing NHF rates. For both models, the anterior compartments demonstrated faster clearance levels (half-times < 0.5 s) and the posterior sections showed slower clearance (half-times < 1.0 s). Both imaging methods showed similar flow-dependent tracer-gas clearance in the models. For the anatomically based model, there was complete tracer-gas removal from the nasal cavities within 1.0 s. The level of clearance in the nasal cavities increased by 1.8 ml/s for every 1.0 l/min increase in the rate of NHF. The study has demonstrated the fast-occurring clearance of nasal cavities by NHF therapy, which is capable of reducing of dead space rebreathing.

No MeSH data available.


Related in: MedlinePlus

Clearance rates in nasal cavities (total volume 55 ml) of the upper airway model (UAM) at NHF rates of 15, 30, and 45 l/min, calculated from the clearance half-times and corresponding volumes of UAM1 and UAM2 ROIs. The clearance rate linearly rises with an increase of NHF. The graph shows that in the static experimental setup NHF of 30 l/min clears the total volume of the nasal cavity within 1 s.
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Figure 5: Clearance rates in nasal cavities (total volume 55 ml) of the upper airway model (UAM) at NHF rates of 15, 30, and 45 l/min, calculated from the clearance half-times and corresponding volumes of UAM1 and UAM2 ROIs. The clearance rate linearly rises with an increase of NHF. The graph shows that in the static experimental setup NHF of 30 l/min clears the total volume of the nasal cavity within 1 s.

Mentions: The total clearance rate from both UAM nasal cavity ROIs expressed in milliliters per second (Fig. 5) has a linear relationship with the NHF rates (15, 30, and 45 l/min) tested (r = 0.92, P < 0.001): every 1 l/min increase in NHF results in 1.8 ml/s increased clearance in the nasal cavities.


Nasal high flow clears anatomical dead space in upper airway models.

Möller W, Celik G, Feng S, Bartenstein P, Meyer G, Oliver E, Schmid O, Tatkov S - J. Appl. Physiol. (2015)

Clearance rates in nasal cavities (total volume 55 ml) of the upper airway model (UAM) at NHF rates of 15, 30, and 45 l/min, calculated from the clearance half-times and corresponding volumes of UAM1 and UAM2 ROIs. The clearance rate linearly rises with an increase of NHF. The graph shows that in the static experimental setup NHF of 30 l/min clears the total volume of the nasal cavity within 1 s.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482836&req=5

Figure 5: Clearance rates in nasal cavities (total volume 55 ml) of the upper airway model (UAM) at NHF rates of 15, 30, and 45 l/min, calculated from the clearance half-times and corresponding volumes of UAM1 and UAM2 ROIs. The clearance rate linearly rises with an increase of NHF. The graph shows that in the static experimental setup NHF of 30 l/min clears the total volume of the nasal cavity within 1 s.
Mentions: The total clearance rate from both UAM nasal cavity ROIs expressed in milliliters per second (Fig. 5) has a linear relationship with the NHF rates (15, 30, and 45 l/min) tested (r = 0.92, P < 0.001): every 1 l/min increase in NHF results in 1.8 ml/s increased clearance in the nasal cavities.

Bottom Line: There was a similar tracer-gas clearance characteristic in the tube model and the upper airway model: clearance half-times were below 1.0 s and decreased with increasing NHF rates.The level of clearance in the nasal cavities increased by 1.8 ml/s for every 1.0 l/min increase in the rate of NHF.The study has demonstrated the fast-occurring clearance of nasal cavities by NHF therapy, which is capable of reducing of dead space rebreathing.

View Article: PubMed Central - PubMed

ABSTRACT
Recent studies showed that nasal high flow (NHF) with or without supplemental oxygen can assist ventilation of patients with chronic respiratory and sleep disorders. The hypothesis of this study was to test whether NHF can clear dead space in two different models of the upper nasal airways. The first was a simple tube model consisting of a nozzle to simulate the nasal valve area, connected to a cylindrical tube to simulate the nasal cavity. The second was a more complex anatomically representative upper airway model, constructed from segmented CT-scan images of a healthy volunteer. After filling the models with tracer gases, NHF was delivered at rates of 15, 30, and 45 l/min. The tracer gas clearance was determined using dynamic infrared CO2 spectroscopy and 81mKr-gas radioactive gamma camera imaging. There was a similar tracer-gas clearance characteristic in the tube model and the upper airway model: clearance half-times were below 1.0 s and decreased with increasing NHF rates. For both models, the anterior compartments demonstrated faster clearance levels (half-times < 0.5 s) and the posterior sections showed slower clearance (half-times < 1.0 s). Both imaging methods showed similar flow-dependent tracer-gas clearance in the models. For the anatomically based model, there was complete tracer-gas removal from the nasal cavities within 1.0 s. The level of clearance in the nasal cavities increased by 1.8 ml/s for every 1.0 l/min increase in the rate of NHF. The study has demonstrated the fast-occurring clearance of nasal cavities by NHF therapy, which is capable of reducing of dead space rebreathing.

No MeSH data available.


Related in: MedlinePlus