Inhalation therapy in mechanical ventilation

Bronchodilator administration by pressurized inhaler during invasive mechanical ventilation in adults: A scoping review

OBJECTIVE

To identify the administration characteristics and connection methods of bronchodilators by pressurized inhalers to the ventilatory circuit of patients under invasive mechanical ventilation.

METHODS

A scope review was conducted following the PRISMA for Scoping Review, using the PubMed, Embase Elsevier, Cochrane Library, and Lilacs databases without language restrictions, up to July 2023. Eligible sources included reviews and consensuses (based on clinical studies), experimental and observational studies involving adult patients admitted to the intensive care unit and undergoing invasive mechanical ventilation, regardless of the underlying condition, who used bronchodilator drugs contained in pressurized inhalers. Information regarding inhalation technique, pressurized inhalers connection mode to the circuit, and patient care were collected by 2 researchers independently, with discrepancies resolved by a third reviewer. Studies involving bronchodilators combined with other pharmacological classes in the same device, as well as reviews containing preclinical studies, were excluded.

RESULTS

In total, 23 publications were included, comprising 19 clinical trials and 4 non-randomized experimental studies. Salbutamol (albuterol) was the bronchodilator of study in the majority of the articles (n=18), and the spacer device was the most commonly used to connect the pressurized inhaler to the circuit (n=15), followed by an in-line adapter (n=3), and a direct-acting device without chamber (n=3). Concerning the pressurized inhaler placement in the circuit, 18 studies positioned it in the inspiratory limb, and 19 studies synchronized the jet actuation with the start of the inspiratory phase. Agitation of the pressurized inhaler before each actuation, waiting time between actuations, airway suction before administration, and semi-recumbent patient positioning were the most commonly described measures across the studies.

CONCLUSIONS

This review provided insights into the aspects related to inhalation technique in mechanically ventilated patients, as well as the most prevalent findings and the existing gaps in knowledge regarding bronchodilator administration in this context. The evidence indicates the need for further research on this subject.

Impact of gas humidification and nebulizer position under invasive ventilation: preclinical comparative study of regional aerosol deposition

Successful aerosol therapy in mechanically ventilated patients depends on multiple factors. Among these, position of nebulizer in ventilator circuit and humidification of inhaled gases can strongly influence the amount of drug deposited in airways. Indeed, the main objective was to preclinically evaluate impact of gas humidification and nebulizer position during invasive mechanical ventilation on whole lung and regional aerosol deposition and losses. Ex vivo porcine respiratory tracts were ventilated in controlled volumetric mode. Two conditions of relative humidity and temperature of inhaled gases were investigated. For each condition, four different positions of vibrating mesh nebulizer were studied: (i) next to the ventilator, (ii) right before humidifier, (iii) 15 cm to the Y-piece adapter and (iv) right after the Y-piece. Aerosol size distribution were calculated using cascade impactor. Nebulized dose, lung regional deposition and losses were assessed by scintigraphy using 99mtechnetium-labeled diethylene-triamine-penta-acetic acid. Mean nebulized dose was 95% ± 6%. For dry conditions, the mean respiratory tract deposited fractions reached 18% (± 4%) next to ventilator and 53% (± 4%) for proximal position. For humidified conditions, it reached 25% (± 3%) prior humidifier, 57% (± 8%) before Y-piece and 43% (± 11%) after this latter. Optimal nebulizer position is proximal before the Y-piece adapter showing a more than two-fold higher lung dose than positions next to the ventilator. Dry conditions are more likely to cause peripheral deposition of aerosols in the lungs. But gas humidification appears hard to interrupt efficiently and safely in clinical use. Considering the impact of optimized positioning, this study argues to maintain humidification.

Influence of Mechanical Ventilation Modes on the Efficacy of Nebulized Bronchodilators in the Treatment of Intubated Adult Patients with Obstructive Pulmonary Disease

BACKGROUND

Little has been reported in terms of clinical outcomes to confirm the benefits of nebulized bronchodilators during mechanical ventilation (MV). Electrical Impedance Tomography (EIT) could be a valuable method to elucidate this gap.

OBJECTIVE

The purpose of this study is to evaluate the impact of nebulized bronchodilators during invasive MV with EIT by comparing three ventilation modes on the overall and regional lung ventilation and aeration in critically ill patients with obstructive pulmonary disease.

METHOD

A blind clinical trial in which eligible patients underwent nebulization with salbutamol sulfate (5 mg/1 mL) and ipratropium bromide (0.5 mg/2 mL) in the ventilation mode they were receiving. EIT evaluation was performed before and after the intervention. A joint and stratified analysis into ventilation mode groups was performed, with p < 0.05.

RESULTS

Five of nineteen procedures occurred in controlled MV mode, seven in assisted mode and seven in spontaneous mode. In the intra-group analysis, the nebulization increased total ventilation in controlled (p = 0.04 and ⅆ = 2) and spontaneous (p = 0.01 and ⅆ = 1.5) MV modes. There was an increase in the dependent pulmonary region in assisted mode (p = 0.01 and ⅆ = 0.3) and in spontaneous mode (p = 0.02 and ⅆ = 1.6). There was no difference in the intergroup analysis.

CONCLUSIONS

Nebulized bronchodilators reduce the aeration of non-dependent pulmonary regions and increase overall lung ventilation but there was no difference between the ventilation modes. As a limitation, it is important to note that the muscular effort in PSV and A/C PCV modes influences the impedance variation, and consequently the aeration and ventilation values. Thus, future studies are needed to evaluate this effort as well as the time on ventilator, time in UCI and other variables.

Effects of jet nebulization on ventilator performance with different invasive ventilation modes: A bench study

Background

The effects of jet nebulization on ventilator performance in the volume control mode (VC) and pressure control mode (PC) of ventilation have not been determined.

Objectives

The present study investigated the impact of jet nebulization on ventilator performance in different modes in vitro.

Methods

Two types of jet nebulizer (ventilator-integrated jet nebulizers, external jet nebulizer) and six types of ventilator were connected with a simulated lung to simulate aerosol therapy during mechanical ventilation. The ventilation modes were set to VC and PC, and the driving flows of external jet nebulizer were set at 4 L/min and 8 L/min, respectively. Jet nebulizers were placed between patient airway and Y-piece or at 15 cm from the Y-piece in the inspiratory limb. The effects of jet nebulization were compared with the baseline of triggering performance, control performance, and tidal volume under different experimental conditions.

Results

Ventilator-integrated jet nebulizers had no effect on ventilator performance in different modes (all P &gt; 0.05). However, the effects of external jet nebulizers on ventilator performance varied widely: for triggering performance, all parameters were increased in different modes and nebulization positions (all P &lt; 0.05), including the time from the beginning of the inspiratory effort to the lowest value of airway pressure needed to trigger the ventilator (TPmin), the time to trigger (Ttrig), and the magnitude of airway pressure drop needed to trigger (Ptrig); for control performance, peak inspiratory pressure (Ppeak) and peak inspiratory flow(Pflow) were increased in the VC mode (P &lt; 0.05), but not significantly changed in the PC mode (P &gt; 0.05);the actual tidal volume (VT) and expiratory tidal volume monitored (VTe) were significantly increased (P &lt; 0.05), however, the inspiratory tidal volume monitored (VTi) was not affected by jet nebulization in the VC mode. In the PC mode, there were no significant changes in VT, whereas VTi decreased and VTe increased (P &lt; 0.05). The higher the driving flow of external jet nebulizers, the stronger the impact on ventilator performance (all P &lt; 0.05).

Conclusion

Triggering performance was decreased in both the VC and PC modes when using an external jet nebulizer, while the effects of nebulization on control performance and tidal volume varied significantly.

The Potential Synergistic Risk of Albuterol and Vasoactives in Acute Lung Injury Trials

Background:

Critically ill patients are often prescribed both inhaled beta-agonists and intravenous vasoactive; however, the interaction of the additive beta-agonist effects of these 2 agents remains largely uncharacterized.

Objective:

The purpose of this study was to evaluate how concomitant use of albuterol and vasoactive or inotropes affected ventilator-free days (VFDs) by re-analyzing the data from the Albuterol to Treat Acute Lung Injury (ALTA) trial.

Methods:

In this study, subjects were grouped to albuterol-vasoactive (n = 84) versus (vs) placebo-vasoactive (n = 62). Ventilator-free days, intensive care unit (ICU)-free days, organ failure-free days, cardiovascular adverse events, and 90-day mortality were compared. The primary outcome was VFDs.

Results:

Patients in the albuterol-vasoactive group had significantly fewer VFDs than patients in the placebo-vasoactive group (11 vs 19, P = 0.05). Patients in the albuterol-vasoactive group also had significantly fewer ICU-free days (9.5 vs 18.5, P = .006). The 90-day mortality was similar between groups (36.9% vs 27.4%, P = .20). Similarly, no significant difference in cardiac adverse events between the groups (14.3% vs 11.3%, P = 0.59).

Conclusion and Relevance:

This study has shown fewer VFDs for patients who received both vasoactive and albuterol. There were also fewer ICU-free days when compared to those on vasoactive only. Given the common use of both agents, a prospective evaluation of the additive adverse effects of beta-agonism is warranted.

Aerosol therapy during mechanical ventilation in intensive care units: A questionnaire-based survey of 2203 ICU medical staff in China

Background

To describe the current status of aerosol therapy during mechanical ventilation (MV) and the practice, knowledge, and beliefs about aerosol therapy in physicians working in the intensive care unit (ICU) in China.

Methods

A physician self-administered questionnaire-based cross-sectional survey was carried out from January 2019 to July 2019. An electronic questionnaire was designed, and physicians who worked regularly in ICUs across several hospitals were contacted through WeChat. Answers to all questions and the general characteristics of physicians who answered the questionnaire were collected and analyzed.

Results

A total of 2203 medical staff who regularly worked in the ICUs completed this questionnaire (9.0% missing data); 87.7% of the participants were doctors. Most respondents claimed that they often administered aerosolization therapy. Ultrasonic atomizer (50.7%) and jet nebulizer (48.6%) were the most commonly used atomization devices. Bronchodilators (65.8%) and steroids (66.3%) were the most frequently aerosolized drugs during MV. During nebulization, ventilator settings were never changed by 32.7% of respondents. Only 49.1% of respondents knew the appropriate place for a nebulizer. Further, 62.7% of respondents using heated humidifiers reported turning them off during nebulization. Specific knowledge about droplet size and nebulization yield was poor. Respondents from tertiary hospitals and those with higher technical title or work experience tended to have better accuracy than those from primary hospitals or with lower technical titles (P < 0.050).

Conclusions

Aerosol therapy was commonly used during MV, and the most frequent drugs were bronchodilators and steroids. Scientific knowledge about the optimal implementation of aerosol therapy during MV seemed deficient.

Effect of Tiotropium Soft Mist Inhalers on Dynamic Changes in Lung Mechanics of Patients with Chronic Obstructive Pulmonary Disease Receiving Mechanical Ventilation: A Prospective Pilot Study

The effects of tiotropium bromide soft mist inhalers (SMIs) in patients with chronic obstructive pulmonary disease (COPD) receiving mechanical ventilation remain unexplored. This study investigated the dynamic effects of a tiotropium SMI on lung mechanics and gas exchange in these patients. We analyzed 11 mechanically ventilated and hemodynamically stable patients with COPD who experienced acute exacerbation and were ready to be weaned from the ventilator. Two puffs of tiotropium (2.5 μg/puff) were administered with a T-adaptor connected to the ventilator circuit. Lung mechanics—peak inspiratory pressure, plateau pressure, mean airway pressure, maximum respiratory resistance (Rrs), and gas exchange function—were analyzed. The two-puff tiotropium SMI treatment led to the greatest reduction in Rrs at 6 h, with the Rrs returning to baseline gradually, and significantly improved the PaO₂/FiO₂ ratio at 24 h. Compared with baseline values, tiotropium SMI had the strongest effect on Rrs between hours 3 and 6 but did not significantly affect hemodynamic parameters. Tiotropium SMI administration in mechanically ventilated patients with COPD achieved the greatest reduction in Rrs at 6 h and significantly improved the PaO₂/FiO₂ ratio at 24 h. Future studies should investigate whether the bronchodilation effect can be improved with increased dosage or frequency.

Medication Use and Risk of Delirium in Mechanically Ventilated Patients

One of the principal complications in patients in the intensive care unit, particularly in those receiving mechanical ventilation, is medication-induced delirium. The present study aimed to intensively analyze pharmaceutical factors affecting the development of delirium in mechanically ventilated patients using the electronic health records. The present study was designed as a retrospective case-control study. The delirium group included 500 mechanically ventilated patients. The non-delirium group included 2,000 patients who were hospitalized during the same period as the delirium group and received mechanical ventilation. A total of seven types of medications (narcotic analgesics, non-narcotic analgesics, psychopharmaceuticals, sleep aid medications, anticholinergics, steroids, and diuretics), conventionally used to manage mechanical ventilation, were found to be major risk factors associated with the occurrence of delirium. Since these medications are an integral part of managing mechanically ventilated patients, prudent protocol-based medication approaches are essential to decrease the risk of delirium.

Evaluation of inhaled salbutamol effectiveness under supportive use of electrical impedance tomography in ventilated ICU patients: study protocol for a randomised controlled clinical trial

INTRODUCTION

The inhalative administration of drugs is a non-invasive application form that is regularly used in the treatment of ventilated patients in critical care setting. However, assessment of effectiveness or distribution of nebulised drugs is one of the lacking cornerstones of modern intensive care monitoring. Electrical impedance tomography (EIT) may provide a promising new monitoring and guiding tool for an adequate optimisation of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and evaluate associated pathologies at bedside. This study aims to elucidate the extent to which the effectiveness of inhaled salbutamol can be increased by the additional use of EIT for optimisation of respirator settings.

METHODS AND ANALYSIS

This study is a randomised, open-label, superiority trial conducted on an intensive care unit of a German university hospital, comparing two groups of mechanically ventilated patients with an acute or chronic bronchial airway obstruction according to the effectiveness of inhaled salbutamol with (intervention) or without (control) additional use of EIT for optimising ventilator settings. The primary outcome is change in airway resistance 30 min after salbutamol inhalation.

ETHICS AND DISSEMINATION

The study has received approval from the Ethics Committee of the Medical Faculty of Ruhr-University Bochum (17-6306). The results will be made available to critical care survivors, their caregivers, the funders, the critical care societies and other researchers by publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

DRKS00014706; Pre-results.