Effect of different connection adapters on aerosol delivery in invasive ventilation setting; an in-vitro study

Aerosol therapy in adult critically ill patients: a consensus statement regarding aerosol administration strategies during various modes of respiratory support

BACKGROUND

Clinical practice of aerosol delivery in conjunction with respiratory support devices for critically ill adult patients remains a topic of controversy due to the complexity of the clinical scenarios and limited clinical evidence.

OBJECTIVES

To reach a consensus for guiding the clinical practice of aerosol delivery in patients receiving respiratory support (invasive and noninvasive) and identifying areas for future research.

METHODS

A modified Delphi method was adopted to achieve a consensus on technical aspects of aerosol delivery for adult critically ill patients receiving various forms of respiratory support, including mechanical ventilation, noninvasive ventilation, and high-flow nasal cannula. A thorough search and review of the literature were conducted, and 17 international participants with considerable research involvement and publications on aerosol therapy, comprised a multi-professional panel that evaluated the evidence, reviewed, revised, and voted on recommendations to establish this consensus.

RESULTS

We present a comprehensive document with 20 statements, reviewing the evidence, efficacy, and safety of delivering inhaled agents to adults needing respiratory support, and providing guidance for healthcare workers. Most recommendations were based on in-vitro or experimental studies (low-level evidence), emphasizing the need for randomized clinical trials. The panel reached a consensus after 3 rounds anonymous questionnaires and 2 online meetings.

CONCLUSIONS

We offer a multinational expert consensus that provides guidance on the optimal aerosol delivery techniques for patients receiving respiratory support in various real-world clinical scenarios.

Preliminary bronchodilator dose effect on aerosol-delivery through different nebulizers in noninvasively ventilated COPD patients

Objectives: This study aimed to evaluate the effect of a preliminary bronchodilator dose on the aerosol-d elivery by different nebulizers in noninvasively ventilated chronic obstructive pulmonary disease (COPD) patients. Method: COPD patients were randomized to receive study doses of 800 µg beclomethasone dipropionate (BPD) nebulized by either a vibrating mesh nebulizer (VMN) or a jet nebulizer (JN) connected to MinimHal spacer device. On a different day, the nebulized dose of beclomethasone was given to each patient by the same aerosol generator with and without preceded two puffs (100 µg each) of salbutamol delivered by a pressurized-metered dose inhaler. Urinary BPD and its metabolites in 30 min post-inhalation samples and pooled up to 24 h post-inhalation were measured. On day 2, ex-vivo studies were performed with BPD collected on filters before reaching patients which were eluted from filters and analyzed to estimate the total emitted dose.Results: The highest urinary excretion amounts of BPD and its metabolites 30 min and 24 h post-inhalation were identified with pMDI + VMN compared with other regimens(p < 0.001). The amounts of BPD and its metabolites excreted 30 min post inhalation had approximately doubled with pMDI + JN compared with JN delivery (p < 0.05). No significant effect was found in the ex-vivo study results except between VMN and JN with a significant superiority of the VMN (p < 0.001).Conclusion: Using a preliminary bronchodilator dose before drug nebulization significantly increased the effective lung dose of the nebulized drug with both VMNs and JNs. However, adding a preliminary bronchodilator dose increased the 24 hr cumulative urinary amount of the drug representing higher systemic delivery of the drug, which in turn could result in higher systemic side effects.

Aerosol delivery through high flow nasal cannula compared to biphasic positive airway pressure, at two different pressure: an in-vitro study

Background

Both non-invasive ventilation and high flow oxygen therapy are preferred over low flow oxygen therapy in many conditions. Nebulizers, for aerosol delivery, can be used within them without interrupting the circuit. The present study aimed to compare the efficiency of drug delivery within high flow nasal cannula (HFNC) and biphasic positive airway pressure (BiPAP) ventilation mode using two different inspiratory positive airway pressures. The aerosol delivery was examined in HFNC system at low flow, 5 L min−1, and BiPAP non-invasive ventilation under 2 different pressures [high pressure; inspiratory positive airway pressure/expiratory positive airway pressure (IPAP/EPAP) of 20/5 cm water, and low pressure; IPAP/EPAP of 10/5 cm water]. The total inhalable dose (TID) was measured by inserting an Aerogen Solo nebulizer installed with 1 mL salbutamol respiratory solution (5000 μg mL−1) within the circuit, and the salbutamol was collected on an inhalation filter placed in a filter holder connected to a breathing simulator. The breathing simulator was adjusted at a tidal volume of 500 mL, respiratory rate of 15 breaths min−1, and inhalation to exhalation (I:E) ratio of 1:1 for the adult setting. In each technique of the three (HFNC, and low, and high-pressures BiPAP), TID was determined 5 times (n = 5). For particle size characterization, cooled Anderson Cascade Impactor (ACI) was inserted instead of the inhalation filter and the breathing simulator with the same scheme. In each technique of the three, particle size characterization was determined 3 times (n = 3).

Results

The BiPAP mode at low inspiratory pressure had the highest TID, followed by HFNC at flow 5 L min−1, then BiPAP mode at high inspiratory pressure. There was a significant difference only between low and high inspiratory pressure modes of BiPAP mode. Low-inspiratory pressure BiPAP delivered the highest mean ± SD fine particle dose (FPD). It was significantly higher than that delivered in high inspiratory pressure BiPAP, and HFNC. Also, FPD in HFNC was significantly higher than that in high inspiratory pressure BiPAP. HFNC system had the smallest mass median aerodynamic diameter (MMAD) and the highest FPF followed by low then high inspiratory pressure BiPAP.

Conclusions

Increasing the inspiratory positive airway pressure in BiPAP, from 10 to 20 cm water, decreased the total inhalable dose and FPF nearly by half. Low inspiratory pressure BiPAP delivered the highest TID and FPD. The HFNC system at low oxygen flow resulted in the least MMAD, and the highest FPF. Using HFNC delivered a TID that was non-significant from that delivered by low inspiratory pressure BiPAP.

Graphical Abstract

Lung deposition and systemic bioavailability of dose delivered to smoker compared with non-smoker COPD subjects

INTRODUCTION

Inhaled drugs are the most commonly used class of medications for COPD subjects. No studies have been performed to assess the influence of smoking on lung deposition of aerosolized medication, especially for the exacerbated COPD subject. The present study aimed to assess the influence of smoking on the lung deposition of the aerosol delivered to exacerbated COPD subjects.

METHODS

Twenty-four exacerbated COPD subjects using automatic continuous positive airway pressure (Auto-CPAP), 12 smokers (six females) and 12 non-smokers (six females) were recruited in the study. The subjects participated in the study received four salbutamol study doses; 1200 µg (12 puffs 100 µg/puff) of salbutamol emitted from pMDI canister connected to AeroChamber MV spacer; 1200 µg of salbutamol emitted from pMDI canister connected to Combihaler spacer; 1 mL of salbutamol respirable solution (5000 µg/mL) nebulized by Aerogen Solo connected to its T-piece; and 1 mL of salbutamol respirable solution nebulized by Aerogen Solo connected to Combihaler spacer with 2 puffs salbutamol MDI (200 µg salbutamol) before nebulisation. The subjects were randomised to receive the four selected dose-adaptor combination in a sealed envelope design on days 1, 3, 5 and 7. A washout period of 24 hours was provided between each salbutamol dosing. Auto-CPAP was adjusted at non-invasive ventilation mode with the integrated heated humidifier, as a source of humidity. Urine samples were provided by subjects, 30 minutes and cumulatively 24 hours post inhalation, as an index of the relative and systemic bioavailability, respectively, and aliquots were retained for salbutamol analysis using solid-phase extraction and high-performance liquid chromatography (HPLC). On day 2 of the study, a collecting filter was placed between the aerosol generator and the subject's mask so that the subjects would not inhale the salbutamol delivered. The same study doses and/or adapters were delivered to each subject, with filters changed with each dose-adapter combination. Salbutamol entrained on the filter was desorbed to be analysed by the HPLC.

RESULTS

Significantly higher lung deposition (30 minutes urinary salbutamol) was detected with the non-smoker compared with smokers (P < .05). Significantly higher systemic bioavailability (pooled 24-hour urinary salbutamol) for smokers compared with non-smokers was found with Aerogen Solo connected to its T-piece and CombiHaler spacer with pMDI (P < .05) only. Significantly higher amount desorbed from the ex-vivo filter were found from pMDI with both spacers in non-smokers (P < .05) compared with the smokers.

CONCLUSION

The study demonstrated that smoking reduced the lung deposition of inhaled salbutamol delivered by nebulizer or pMDI. However, the smoking effect on cytochrome p450 was observed to increase systemic absorption of the ingested portion of the inhaled dose. The lower lung deposition and possible higher systemic absorption should be taken into consideration while prescribing inhaled medication to COPD smokers especially exacerbated patients that need ventilation. Further studies are needed.