Abstract
Background:
Heated humidified high-flow therapy (HHHF) is frequently used with spontaneous breathing tracheostomized patients. However, the efficiency of in-line placement of nebulizer via HHHF remains unclear. We aimed to assess the impact of the nebulizer placement, flow settings, and interfaces on aerosol delivery using a vibrating mesh nebulizer (VMN) with HHHF for tracheostomized adults.
Methods:
A simulated spontaneous breathing model of a tracheostomized adult (tidal volume 470 mL, frequency 21 breaths/min, inspiratory time: 1.1 s, and trach tube size 8.0 mm), with a collecting filter placed between the trach tube and model lung. Albuterol sulfate of 2.5 mg/3 mL was aerosolized via VMN placed of distal (near the humidifier) and proximal to the airway with HHHF (Airvo2), using trach adaptor and trach collar, with gas flows of 15 vs. 30 vs. 45 L/min (no. = 5). The drug was eluted from the collecting filter and assayed with ultraviolet spectrophotometry (276 nm). The Mann Whiteney test was used to compare the differences in the inhaled dose between nebulizer placements and interfaces, while Kruskal-Wallis test was used to assess the differences in the inhaled doses among various gas flows.
Results:
The percent of albuterol (mean ± SD) inhaled is shown in Table 1. The inhaled dose increased as flow decreased, regardless of the interface and nebulizer placements (all P < .05). With trach adaptor, the inhaled dose with VMN placed at distal was higher than VMN placed at proximal placement in all flow settings (all P < .05). With proximal placement, the inhaled dose was higher with the trach collar than the trach adapter at flows of 30 and 45 L/min (both P = .009), while the inhaled dose was lower with trach collar than tach adaptor with in-line distal placement only at flow of 30 L/min (8.7 ± .8 vs 11.5 ± 0.8%, P = .009).
Conclusions:
In this model of tracheostomized adults, aerosol delivery from VMN during HHHF, increased as flow decreased. With the trach adapter, the inhaled dose was greater with VMN in distal than proximal placement. In contrast, use of trach collar with VMN in proximal position was greater at mid and high flow settings.
Values are presented as mean±SD%; VMN: vibrating mesh nebulizer; HHHF: heated humidified high-flow therapy; Distal: VMN placed near the humidifier; Proximal: VMN placed near the airway.
Flow chart of the study design View all access options for this article.Percentage of inhaled dose delivered through tracheostomy tube via in-line VMN at proximal and distal placement with HHHF in various conditions
Interface
Flow (L/min)
Inhaled dose based on nebulizer placement, %
P value
Proximal
Distal
Trach adaptor
15
15.4 ± 1.4
23.8 ± 1.1
.009
30
9.0 ± .7
11.5 ± .8
.009
45
3.7 ± .9
6.8 ± 1.2
.009
P value
.002
.002
Trach collar
15
16.4 ± 2.1
21.3 ± 1.9
.009
30
13.2 ± 1.1
8.7 ± .8
.009
45
8.8 ± .9
5.4 ± .8
.009
P value
.003
.002
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