Aerosol spread with use of high-flow nasal cannulae: a computational fluid dynamics analysis.
Ontology highlight
ABSTRACT:
SUBMITTER: Kobayashi H
PROVIDER: S-EPMC7292944 | biostudies-literature | 2020 Sep
REPOSITORIES: biostudies-literature
Publications
Aerosol spread with use of high-flow nasal cannulae: a computational fluid dynamics analysis.
Kobayashi H H Takimoto T T Kitaoka H H Kijima T T
The Journal of hospital infection 20200613 1
Similar Datasets
Project description: Not available
| S-EPMC6481761 | biostudies-literature
Project description: Not available
| S-EPMC8094160 | biostudies-literature
Project description:BackgroundIn obese patients, preoxygenation with non-invasive ventilation (NIV) was reported to improve outcomes compared with facemask. In this setting, high-flow nasal cannulae (HFNC) used before and during intubation has never been studied against NIV.MethodsThe PREOPTIPOP study is a randomised, single-centre, open-labelled, controlled trial including obese patients requiring intubation before scheduled surgery. Patients were randomised to receive preoxygenation by HFNC or NIV. HFNC was maintained throughout intubation whereas NIV was removed when apnea occurred to perform laryngoscopy. The study was designed to assess the superiority of HNFC. The primary outcome was the lowest level of end-tidal oxygen concentration (EtO2) within 2 min after intubation. Secondary outcomes included drop in pulse oximetry and complications related to intubation.Main findingsA total of 100 patients were randomised. The intent-to-treat analysis found median [IQR] lowest EtO2 of 76% [66-82] for HFNC and 88% [82-90] for NIV (mean difference - 12·1 [- 15·1 to - 8·5], p < 0·0001). Mild desaturation below 95% was more frequent with HFNC (30%) than with NIV (12%) (relative risk 2·5, IC 95% [1·1 to 5·9], p = 0·03) and median lowest SpO2 during intubation was 98% [93-99] in HFNC vs. 99% [97-100] in NIV (p = 0·03). Severe and moderate complications were not different but patients reported more discomfort with NIV (28%) vs. HFNC (4%), p = 0·001.InterpretationCompared with NIV, preoxygenation with HFNC in obese patients provided lower EtO2 after intubation and a higher rate of desaturation < 95%.FundingInstitutional funding, additional grant from Fisher & Paykel.Trial registrationClinical trial Submission: April 10, 2017. Registry name: Preoxygenation Optimization in Obese Patients: High-flow Nasal Cannulae Oxygen Versus Non-invasive Ventilation: A Single-centre Randomised Controlled Study. The PREOPTIPOP Study. Clinicaltrials.gov identifier: NCT03106441 N°ID RCB: 2017-A00305-48. Institutional review Board: CPP Nord-Ouest I, registration number 019/2017. URL registry:https://clinicaltrials.gov/ct2/show/NCT03106441.
| S-EPMC6737343 | biostudies-literature
Project description:The objective of this research was to develop an inlet to meet the inhalable sampling criterion at 10 l min(-1) flow using the standard, 37-mm cassette. We designed a porous head for this cassette and evaluated its performance using computational fluid dynamics (CFD) modeling. Particle aspiration efficiency was simulated in a wind tunnel environment at 0.4 m s(-1) freestream velocity for a facing-the-wind orientation, with sampler oriented at both 0 degrees (horizontal) and 30 degrees down angles. The porous high-flow sampler oriented 30 degrees downward showed reasonable agreement with published mannequin wind tunnel studies and humanoid CFD investigations for solid particle aspiration into the mouth, whereas the horizontal orientation resulted in oversampling. Liquid particles were under-aspirated in all cases, however, with 41-84% lower aspiration efficiencies relative to solid particles. A sampler with a single central 15-mm pore at 10 l min(-1) was also investigated and was found to match the porous sampler's aspiration efficiency for solid particles; the single-pore sampler is expected to be more suitable for liquid particle use.
| S-EPMC4780251 | biostudies-literature
Project description:Potential exposure from hazardous dusts may be assessed by evaluating the dustiness of the powders being handled. Dustiness is the tendency of a powder to aerosolize with a given input of energy. We have previously used computational fluid dynamics (CFD) to numerically investigate the flow inside the European Standard (EN15051) Rotating Drum dustiness tester during its operation. The present work extends those CFD studies to the widely used Heubach Rotating Drum. Air flow characteristics are investigated within the Abe-Kondoh-Nagano k-epsilon turbulence model; the aerosol is incorporated via a Euler-Lagrangian multiphase approach. The air flow inside these drums consists of a well-defined axial jet penetrating relatively quiescent air. The spreading of the Heubach jet results in a fraction of the jet recirculating as back-flow along the drum walls; at high rotation rates, the axial jet becomes unstable. This flow behavior qualitatively differs from the stable EN15051 flow pattern. The aerodynamic instability promotes efficient mixing within the Heubach drum, resulting in higher particle capture efficiencies for particle sizes d < 80 μm.
| S-EPMC10193456 | biostudies-literature
Project description:The Difficult Airway Society recommends that all patients should be pre-oxygenated before the induction of general anaesthesia, but this may not always be easy or comfortable and anaesthesia may often be induced without full pre-oxygenation. We tested the hypothesis that high-flow nasal oxygen cannulae would be easier and more comfortable than facemasks for pre-oxygenation. We randomly allocated 199 patients undergoing elective surgery aged ≥ 10 years to pre-oxygenation using either high-flow nasal oxygen or facemask. Ease and comfort were assessed by anaesthetists and patients on 10-cm visual analogue scale and six-point smiley face scale, respectively. Secondary endpoints included end-tidal oxygen fraction after securing a definitive airway and time to secure an airway. A mean difference (95%CI) between groups in ratings of -0.76 (-1.25 to -0.27) cm for ease of use (p = 0.003) and -0.45 (-0.75 to -0.13) points for comfort (p = 0.006), both favoured high-flow nasal oxygen. A mean difference (95%CI) between groups in end-tidal oxygen fraction of 3.89% (2.41-5.37%) after securing a definitive airway also favoured high-flow nasal oxygen (p < 0.001). There was no significant difference between groups in the number of patients with hypoxaemia (Sp O2 < 90%) or severe hypoxaemia (Sp O2 < 85%) lasting ≥ 1 min or ≥ 2 min; in the proportion of patients with an end-tidal oxygen fraction < 87% in the first 5 min after tracheal intubation (52.2% vs. 58.9% in facemask and high-flow nasal oxygen groups, respectively; p = 0.31); or in time taken to secure an airway (11.6 vs. 12.2 min in facemask and high-flow nasal oxygen groups, respectively; p = 0.65). In conclusion, we found pre-oxygenation with high-flow nasal oxygen to be easier for anaesthetists and more comfortable for patients than pre-oxygenation with a facemask, with no clinically relevant differences in end-tidal oxygen fraction after securing a definitive airway or time to secure an airway. The differences in ease and comfort were modest.
| S-EPMC9826500 | biostudies-literature
Project description: Not available
| S-EPMC8408536 | biostudies-literature
Project description: Not available
| S-EPMC8408534 | biostudies-literature
Project description: Not available
| S-EPMC10117236 | biostudies-literature
Project description:A perfusion system was developed to generate well defined flow conditions within a well of a standard multidish. Human vein endothelial cells were cultured under flow conditions and cell response was analyzed by microscopy. Endothelial cells became elongated and spindle shaped. As demonstrated by computational fluid dynamics (CFD), cells were cultured under well defined but time varying shear stress conditions. A damper system was introduced which reduced pulsatile flow when using volumetric pumps. The flow and the wall shear stress distribution were analyzed by CFD for the steady and unsteady flow field. Usage of the volumetric pump caused variations of the wall shear stresses despite the controlled fluid environment and introduction of a damper system. Therefore the use of CFD analysis and experimental validation is critical in developing flow chambers and studying cell response to shear stress. The system presented gives an effortless flow chamber setup within a 6-well standard multidish.
| S-EPMC2289785 | biostudies-other