| ObjectiveWith the increase in the clinical application of high-flow oxygen therapy,it tends to replace partly non-invasive ventilation,and the use of high-flow oxygen therapy for patients with artificial airways is also more common in intensive care units and other departments.To explore the efficacy and influencing factors of high-flow oxygen via endotracheal intubation combined with aerosol therapy,this in vitro study is specially designed to explore the deposition rate of aerosol in different high-flow parameters.MethodsTo simulate quiet breathing in adult patients with transoral tracheal intubation,an adult transoral tracheal intubation-lung model was established by connecting a transoral tracheal intubation tube to a simulated lung,which provided the respiratory drive for calm breathing in adults(tidal volume of 500 ml,respiratory rate of 14 breaths/min,resistance of 5 cmH2O/L/s,compliance of 50 ml/cmH2O).A highefficiency filter was placed between the simulated lung and the tracheal cannula to capture the aerosolized aerosol mass.The tracheal cannula is connected to one end of the jet nebulizer and the high-flow device is connected to the other end of the jet nebulizer to form an integrated high-flow jet nebulization system,which uses salbutamol sulfate solution for inhalation as the nebulizing drug to simulate high-flow oxygen therapy combined with jet nebulization treatment.The model experiment will vary the parameters of high-flow oxygen therapy,with the flow rate set to 20 L/min,30 L/min,40 L/min,50 L/min,and 70 L/min,and the oxygen concentration set to 21%,50%,and 100%respectively,and the humidity in the pipeline will be measured during the experiment.The drug collected at the filter was eluted after completing each experiment,and the absorbance of the eluted solution was measured using a UV spectrophotometer,and the absorbance-mass curve of the standard concentration gradient salbutamol solution was used to calculate the mass of salbutamol in the eluate.The percentage of the drug mass at the filter to the initial drug mass was used as the aerosol deposition rate.ResultsThe overall distribution of aerosol deposition rates for each flow rate at the same oxygen concentration was statistically different(P ≤ 0.001),with the maximum aerosol deposition rate measured at an oxygen concentration of 50%and a flow rate of 20 L/min,which was 6.57± 0.79%.There was no significant effect of oxygen concentration change on the aerosol deposition rate at the same flow rate.At the same temperature setting,the humidity in the pipeline varies significantly at different flow rates(F=2.955,P=0.04).The effect of flow rate and humidity on aerosol deposition rate may have an interaction effect,which was tested using a linear mixed model with repeated measurement data,and the results of the fixed effects test showed that there was no effect of the humidity in the pipeline on aerosol deposition rate(P=0.67);the results of the covariance parameter estimation showed that there was a difference between individuals in aerosol deposition rate(P<0.001),and the variance of both flow level and in-line humidity was not(P=0.25,P=0.42),and humidity could not be considered to affect the aerosol deposition rate at different flow rates.Flow rate and humidity were selected for the multiple linear regression equation,and the results showed that flow rate was the most significant independent influence on aerosol deposition rate(β=-0.09,t=-14.65,P<0.001),and salbutamol aerosol deposition rate decreased with increasing flow rate,without significant covariance observed.ConclusionThe most significant independent influence on drug-aerosol deposition rate is the flow rate,which decreases with increasing flow rate and reaches a maximum at 20-30 L/min.When the temperature parameter is constant,the humidity in the line is influenced by the flow rate,and it is not clear whether it has an independent effect on the aerosol deposition rate. |
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