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Introduction
High flow nasal cannula (HFNC) provides anopportunity to deliver aerosol to the lung, withoutinterruption of oxygen and ventilatory support. Whilein vitro studies suggest that aerosol during HFNCmay provide drug to the lung, the available evidenceis not sufficient to support clinical practice.
•In vivo study - Randomized and Crossover study.
Table 1. Distribution of aerosol across chambers at 10, 30 and 50 L/min under humidified conditions
Conclusions
Methods
L. Alcoforado 1, A. Ari 2 , J. de Melo Barcelar 1, S. C. S. Brandão 3, J. B Fink 2, A. Dornelas de Andrade 21Universidade Federal de Pernambuco, Department of Physical Therapy, 2Georgia State University; Department of Respiratory Therapy,
3Universidade Federal de Pernambuco, Department of Nuclear Medicine.
Aim
10L/min
(n=08)
30L/min
(n=07)
50L/min
(n=08)
p-value
Lung (%) 11.81±4.90 3.76±1.36* 2.23±0.81** 0.000#
Upper
airway(%)
36.46±10.49 42.46±14.43 46.72±8.58 0.213
Stomach(%) 0.25±0.10 0.69±0.75 0.23±0.32 0.118
Nebulizer(%) 10.29± 5.75 6.89± 4.37 7.63±5.63 0.437
Nasal
Cannula(%)
6.51±2.46 9.76±2.47*** 13.37±3.07** 0.000
Tubing(%) 16.93±4.78 19.08±8.98 16.92 ± 5.64 0.749
Chamber(%) 9.25 ± 4.33 13.08 ± 8.28 7.96 ± 1.74 0.277#
Filter (%) 8.69 ±3.09 4.23 ± 2.41* 4.90 ± 2.77** 0.011
One-Way Anova and #Kruskal-Wallis Test. p<0.05. *10L/min x 30L/min **10 L/min x 50L/min ***30L/min x 50L/min.
Methods Figure 2. HFNC setup withwith oxygen flow throughVM nebulizer at inlet ofhumidifier. A mask withexpiratory filter was used tocapture exhaled aerosol .23 healthy adults
10L/min(n= 8)
30L/min(n=7)
Anthropometric measures and spirometry were performed
Inhaled an aerosol 99mTc – DTPA(activity = 1 mCi )
VMN –total dose volume = 1,0 mlThe inlet of a heated humidifier (F&P 850™ System)
attached to a high flow tubing and nasal cannula (HFNC; OptiflowTM for adult.
Radiation was counted with a scintillation cameratime= 300s; matrix= 256 x 256; view: posterior thorax,
upper airway, and device components
50L/min(n= 8)
Sponsored Research- This study was funded by a grant CNPq-PVE-400801/2013-2
alcoforadoluciana@gmail.com - armeledornelas@yahoo.com .
Aerosol Deposition with Adult High Flow Nasal Cannula: a randomized trial with in vitro assessment
To compare the effect of gas flow and heated humidity onthe deposition and distribution of radiolabeled aerosol froma vibrating mesh nebulizer (VMN) during use of HFNC inhealthy subjects (in vivo) and with an in vitro model. Results
In vitro study methods
Figure 1. Experimental Set-up with Passive Exhalation (A) and Active Exhalation (B)
Lung model : An in-vitro model was used to simulate a spontaneouslybreathing adult lung model with a tidal volume of 500 ml, 12 bpm and I:Eratio 1:2 a temperature of 37 ⁰C. A filter attached to at the bronchi of theteaching mannequin was used to collect aerosol, eluted and measuredusing spectrophotometry at 276nm.
Aerosol delivery through HFNC provided therapeutic levelsof lung deposition in healthy subjects. In vitro modelssimulating active heated/humidified exhalation provided lessoverestimation of dose across conditions than models withpassive unheated exhalation.
A B
Table 2 In vitro deposition as aerosol % dosedelivered via HFNC with heatedhumidifier off and on using a model with active and passive heated exhalation at10, 30 and 50 L/min.
Figure 4. Representative images of radiation in lungs after inhalation ofaerosol via HFNC under heated conditions.
Figure 3 – Aerosol distribution across compartments with HFNC during heated (H) and unheated (U) at flows of 10, 30 and 50 L/min.
HEATED HUMIDIFIER OFF HEATED HUMIDIFIER ON Flow Rate Active
Heated Exhalation
Passive Exhalation
P value* Active Heated Exhalation
Passive Exhalation
P value*
10L/min 13.7 ± 0.94 11.6 ± 1.04 0.010 11.4 ± 0.27 16.5 ± 0.24 0.003 30L/min 7.01 ± 0.63 5.91± 0.21 0.150 5.33 ± 0.18 6.3 ± 0.30 0.001 50L/min 4.51 ± 0.28 3.96 ± 0.37 0.247 2.66 ± 0.08 2.87 ± 0.08 0.199 P value** 0.0001 0.0001 0.0001 0.0001 * Paired Test – T / ** One way ANOVA
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