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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

A: upper airway tube model (TM) made from a sapphire tube and a sodium chloride (NaCl) nozzle with a cannula inserted into the nozzle in front of the IR-heat radiation source (blackbody). Also shown are the pressure ports and the pneumotachographs to monitor pressure and flow within the tube and the cannula. The cannula flow rates [nasal high flow (NHF)] were delivered into the nozzle at 15, 30, and 45 l/min. B: an infrared absorption image (left) and a gamma camera image (right) show the filling stage of the model with CO2 and 81mKr gas before air was flushed into the cannula. Anterior (TM1) and posterior (TM2) ROIs were defined for data analysis.
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Figure 1: A: upper airway tube model (TM) made from a sapphire tube and a sodium chloride (NaCl) nozzle with a cannula inserted into the nozzle in front of the IR-heat radiation source (blackbody). Also shown are the pressure ports and the pneumotachographs to monitor pressure and flow within the tube and the cannula. The cannula flow rates [nasal high flow (NHF)] were delivered into the nozzle at 15, 30, and 45 l/min. B: an infrared absorption image (left) and a gamma camera image (right) show the filling stage of the model with CO2 and 81mKr gas before air was flushed into the cannula. Anterior (TM1) and posterior (TM2) ROIs were defined for data analysis.

Mentions: Nasal high flow (NHF) rates of 15, 30, and 45 l/min of air were generated using a high-flow blower-humidifier (AIRVO 2, Fisher and Paykel Healthcare, New Zealand). The delivered flow was measured by a low-resistance pneumotachograph (Fleisch, Lausanne, Switzerland) and a differential pressure transducer carrier-amplifier system (Validyne, Northridge, CA). The high-flow blower-humidifier was always on, to allow the system to be at stable operational temperatures and flow rates. A valve (Rudolph, Shawnee, KS) is used to alternate between two cannulas, one delivering 81mKr-gas for model filling and the other delivering NHF for clearance of 81mKr-gas. When measurements were taken, the tracer gas was introduced into the model and then the Y-valve directed NHF through the cannula. For the simplified TM experiments (Fig. 1A), a custom-made cannula (ID = 6.3 mm, OD = 7.0 mm, length = 40.0 mm) was used to deliver the NHF, while for the UAM experiments an Optiflow cannula interface (OPT844, Fisher and Paykel Healthcare, New Zealand) was used.


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)

A: upper airway tube model (TM) made from a sapphire tube and a sodium chloride (NaCl) nozzle with a cannula inserted into the nozzle in front of the IR-heat radiation source (blackbody). Also shown are the pressure ports and the pneumotachographs to monitor pressure and flow within the tube and the cannula. The cannula flow rates [nasal high flow (NHF)] were delivered into the nozzle at 15, 30, and 45 l/min. B: an infrared absorption image (left) and a gamma camera image (right) show the filling stage of the model with CO2 and 81mKr gas before air was flushed into the cannula. Anterior (TM1) and posterior (TM2) ROIs were defined for data analysis.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: A: upper airway tube model (TM) made from a sapphire tube and a sodium chloride (NaCl) nozzle with a cannula inserted into the nozzle in front of the IR-heat radiation source (blackbody). Also shown are the pressure ports and the pneumotachographs to monitor pressure and flow within the tube and the cannula. The cannula flow rates [nasal high flow (NHF)] were delivered into the nozzle at 15, 30, and 45 l/min. B: an infrared absorption image (left) and a gamma camera image (right) show the filling stage of the model with CO2 and 81mKr gas before air was flushed into the cannula. Anterior (TM1) and posterior (TM2) ROIs were defined for data analysis.
Mentions: Nasal high flow (NHF) rates of 15, 30, and 45 l/min of air were generated using a high-flow blower-humidifier (AIRVO 2, Fisher and Paykel Healthcare, New Zealand). The delivered flow was measured by a low-resistance pneumotachograph (Fleisch, Lausanne, Switzerland) and a differential pressure transducer carrier-amplifier system (Validyne, Northridge, CA). The high-flow blower-humidifier was always on, to allow the system to be at stable operational temperatures and flow rates. A valve (Rudolph, Shawnee, KS) is used to alternate between two cannulas, one delivering 81mKr-gas for model filling and the other delivering NHF for clearance of 81mKr-gas. When measurements were taken, the tracer gas was introduced into the model and then the Y-valve directed NHF through the cannula. For the simplified TM experiments (Fig. 1A), a custom-made cannula (ID = 6.3 mm, OD = 7.0 mm, length = 40.0 mm) was used to deliver the NHF, while for the UAM experiments an Optiflow cannula interface (OPT844, Fisher and Paykel Healthcare, New Zealand) was used.

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