Exhalation Spreading During Nasal High-Flow Therapy at Different Flow Rates

Dellweg, Dominic; Kerl, Jens; Gena, Amayu Wakoya; Alsaad, Hayder; Voelker, Conrad

doi:10.1097/ccm.0000000000005009

Cited by 5 publications

(7 citation statements)

References 37 publications

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“…22 Indirect technologies used to evaluate the aerosol transmission risk include aerosol particle sizers, smoke light detection, schlieren imaging, and laser light scattering. [23][24][25][26][27][28][29] The latter 3 use imaging to visualize the trajectory of aerosol movement and do not measure aerosol particle size or concentrations. 13,29 Smoke light detection uses externally introduced particles to visualize the exhaled gas from the manikin, and thus it only measures aerosol dispersion potential.…”

Section: Methods To Evaluate Transmission Risk Of Respiratory Virusesmentioning

confidence: 99%

“…25 Interestingly, Dellweg and colleagues evaluated exhaled emission during HFNC at 60 L/min flow on a single healthy subject using a schlieren optical system. 26 The investigators reported that HFNC increased exhaled air dispersion distance compared with baseline. The maximal dispersal distances while normally breathing room air, HFNC at flows of 20 L/min, 40 L/min, and 60 L/min were 0.99 m, 2.18 m, 2.92 m, and 4.10 m, respectively.…”

Section: Oxygen Devices Including High-flow Nasal Cannulamentioning

confidence: 99%

“…The maximal dispersal distances while normally breathing room air, HFNC at flows of 20 L/min, 40 L/min, and 60 L/min were 0.99 m, 2.18 m, 2.92 m, and 4.10 m, respectively. 26 The inconsistent findings between investigators are probably due to the different methodologies employed; schlieren imaging detects exhaled emission through density differences in the room air, whereas smoke light detection mixes smoke (< 1 mm) with the gas flow to enable measurements. Thus, it is not surprising to see longer dispersion distances with higher HFNC flows in the schlieren imaging measurements.…”

Section: Oxygen Devices Including High-flow Nasal Cannulamentioning

confidence: 99%

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Aerosol-Generating Procedures and Virus Transmission

Alolaiwat

Fink

et al. 2022

Respir Care

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During the early phase of the COVID-19 pandemic, many respiratory therapies were classified as aerosol-generating procedures. This categorization resulted in a broad range of clinical concerns and a shortage of essential medical resources for some patients. In the past 2 years, many studies have assessed the transmission risk posed by various respiratory care procedures. These studies are discussed in this narrative review, with recommendations for mitigating transmission risk based on the current evidence.

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Section: Methods To Evaluate Transmission Risk Of Respiratory Virusesmentioning

confidence: 99%

Section: Oxygen Devices Including High-flow Nasal Cannulamentioning

confidence: 99%

Section: Oxygen Devices Including High-flow Nasal Cannulamentioning

confidence: 99%

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Aerosol-Generating Procedures and Virus Transmission

Alolaiwat

Fink

et al. 2022

Respir Care

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“…However, in the case of no mask, the exhaled jet often exceeded the mirror visualization field. In such cases, an extrapolation of the spreading distances outside the mirror area can be done using the reduction of the expired air velocity [ 32 ]. However, in the present study, this was not possible due to the constant physical movement of the subjects and the thermal plume from the subjects’ lower bodies, which made the wavefront of the expired air often indistinguishable in the schlieren recordings.…”

Section: Resultsmentioning

confidence: 99%

“…The latter has been utilized in this study due to the flexibility and high resolution of this approach that provides two-dimensional visualizations of the flow field with virtually no disturbance to the flow. Therefore, this visualization method has been frequently used in recent literature to evaluate indoor air quality topics, such as the spread of air from face masks [ 31 ], from nasal high-flow therapy [ 32 ], from music instruments [ 33 ], and ventilation strategies [ 34 ]. Detailed information about the utilized schlieren imaging system is presented in Section 2.2 .…”

Section: Introductionmentioning

confidence: 99%

The Spread of Exhaled Air and Aerosols during Physical Exercise

Alsaad

Schälte

Schneeweiß

et al. 2023

JCM

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Physical exercise demonstrates a special case of aerosol emission due to its associated elevated breathing rate. This can lead to a faster spread of airborne viruses and respiratory diseases. Therefore, this study investigates cross-infection risk during training. Twelve human subjects exercised on a cycle ergometer under three mask scenarios: no mask, surgical mask, and FFP2 mask. The emitted aerosols were measured in a grey room with a measurement setup equipped with an optical particle sensor. The spread of expired air was qualitatively and quantitatively assessed using schlieren imaging. Moreover, user satisfaction surveys were conducted to evaluate the comfort of wearing face masks during training. The results indicated that both surgical and FFP2 masks significantly reduced particles emission with a reduction efficiency of 87.1% and 91.3% of all particle sizes, respectively. However, compared to surgical masks, FFP2 masks provided a nearly tenfold greater reduction of the particle size range with long residence time in the air (0.3–0.5 μm). Furthermore, the investigated masks reduced exhalation spreading distances to less than 0.15 m and 0.1 m in the case of the surgical mask and FFP2 mask, respectively. User satisfaction solely differed with respect to perceived dyspnea between no mask and FFP2 mask conditions.

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S2k-Leitlinie Nichtinvasive Beatmung als Therapie der akuten respiratorischen Insuffizienz

Westhoff,

Neumann,

Geiseler

et al. 2023

Pneumologie

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ZusammenfassungDie Leitlinienaktualisierung zeigt die Vorteile sowie die Grenzen der NIV bei der Behandlung von akutem Atemversagen im klinischen Alltag und bei unterschiedlichen Indikationen auf.Die nichtinvasive Beatmung (NIV) hat einen hohen Stellenwert bei der Therapie des hyperkapnischen akuten Atemversagens, da sie die Aufenthaltsdauer und den Krankenhausaufenthalt auf der Intensivstation sowie die Mortalität deutlich reduziert.Patienten mit kardiopulmonalem Ödem und akutem Atemversagen sollten zusätzlich zu notwendigen kardiologischen Eingriffen mit kontinuierlichem positivem Atemwegsdruck (CPAP) und Sauerstoff behandelt werden. Dies sollte bereits präklinisch und in der Notaufnahme erfolgen.Bei anderen Formen des akuten hypoxämischen Atemversagens mit nur leicht bis mäßig gestörtem Gasaustausch (PaO2/FiO2 > 150 mmHg) ergibt sich kein signifikanter Vor- oder Nachteil gegenüber nasaler Sauerstoff-High-Flow-Therapie (HFNO). Bei schweren Formen des ARDS ist die NIV mit einer hohen Rate an Behandlungsversagen und Mortalität verbunden, insbesondere in Fällen mit NIV-Versagen und verzögerter Intubation.Zur Präoxygenierung vor der Intubation sollte NIV verwendet werden. Bei Risikopatienten wird eine NIV empfohlen, um Extubationsversagen zu reduzieren. Im Entwöhnungsprozess von der invasiven Beatmung reduziert NIV das Risiko einer Reintubation bei hyperkapnischen Patienten wesentlich. NIV gilt in der Palliativversorgung als nützlich zur Reduzierung von Dyspnoe und zur Verbesserung der Lebensqualität, hier aber in Konkurrenz zur HFNO, das als komfortabler gilt. Mittlerweile wird die NIV auch im präklinischen Bereich empfohlen, insbesondere bei hyperkapnischem Atemversagen und beim Lungenödem.Bei entsprechender Überwachung auf einer Intensivstation kann NIV auch bei pädiatrischen Patienten mit akuter Ateminsuffizienz erfolgreich eingesetzt werden.

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Exhalation Spreading During Nasal High-Flow Therapy at Different Flow Rates

Abstract: Supplemental Digital Content is available in the text.

Cited by 5 publications

References 37 publications

Aerosol-Generating Procedures and Virus Transmission

Aerosol-Generating Procedures and Virus Transmission

The Spread of Exhaled Air and Aerosols during Physical Exercise

S2k-Leitlinie Nichtinvasive Beatmung als Therapie der akuten respiratorischen Insuffizienz

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