The utilization of aerosol therapy in mechanical ventilation patients: a prospective multicenter observational cohort study and a review of the current evidence

Aerosol drug therapy in critically ill patients (Aero-in-ICU study): A multicentre prospective observational cohort study

BACKGROUND

In recent years, a significant understanding of delivering optimal aerosol therapy and the availability of various drugs and devices have led to an increase in its use in clinical practice. There are only a few studies available regarding their use in critically ill patients from a few parts of the world. We aimed to study the practice pattern of aerosol therapy in critically ill patients from Indian intensive care units (ICUs).

METHODS

After ethical approval, this multi-centric prospective observational study was performed over a study period of four weeks. Newly admitted adult patients considered who had an artificial airway and/or ventilation (including non-invasive). Patients were followed up for the next 14 days or until ICU discharge/death (whichever came first) for details of each aerosol therapy, including ongoing respiratory support, drug type, and aerosol-generating device.

RESULTS

From the nine participating centers across India, 218 patients were enrolled. Of 218 enrolled patients, 72.48% received 4884 aerosols with 30.91 ± 27.15 (95%CI: 26.6-35.1) aerosols per patient over 1108 patient days. Approximately 62.7% during IMV, 30.2% during NIV, 2.3% in spontaneously breathing patients with an artificial airway during weaning, and 4.7% were given without an artificial airway after weaning or decannulation. In 59%, a single drug was used, and bronchodilators were the most frequent. The jet nebulizer was the most common, followed by the ultrasonic and vibrating mesh aerosol generator. The ventilator setting was changed in only 6.6% of the aerosol sessions with IMV and none with NIV.

CONCLUSION

Aerosol therapy is frequently used with a wide variation in practices; bronchodilators are the most commonly used drugs, and jet nebulizers are the most widely used.

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.

Acinetobacter baumannii among Patients Receiving Glucocorticoid Aerosol Therapy during Invasive Mechanical Ventilation, China

Acinetobacter baumannii is a nosocomial pathogen associated with severe illness and death. Glucocorticoid aerosol is a common inhalation therapy in patients receiving invasive mechanical ventilation. We conducted a prospective cohort study to analyze the association between glucocorticoid aerosol therapy and A. baumannii isolation from ventilator patients in China. Of 497 enrolled patients, 262 (52.7%) received glucocorticoid aerosol, and A. baumannii was isolated from 159 (32.0%). Glucocorticoid aerosol therapy was an independent risk factor for A. baumannii isolation (hazard ratio 1.5, 95% CI 1.02-2.28; p = 0.038). Patients receiving glucocorticoid aerosol had a higher cumulative hazard for A. baumannii isolation and analysis showed that glucocorticoid aerosol therapy increased A. baumannii isolation in most subpopulations. Glucocorticoid aerosol was not a direct risk factor for 30-day mortality, but A. baumannii isolation was independently associated with 30-day mortality in ventilator patients. Physicians should consider potential A. baumannii infection when prescribing glucocorticoid aerosol therapy.

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 > 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 < 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 < 0.05), but not significantly changed in the PC mode (P > 0.05);the actual tidal volume (VT) and expiratory tidal volume monitored (VTe) were significantly increased (P < 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 < 0.05). The higher the driving flow of external jet nebulizers, the stronger the impact on ventilator performance (all P < 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.

Position of different nebulizer types for aerosol delivery in an adult model of mechanical ventilation

Background

The optimal positions of different types of nebulizer for aerosol delivery remain unclear.

Methods

Three ICU ventilators employing three types of nebulizer were separately connected to a simulated lung to simulate nebulization during invasive ventilation. Assist/control-pressure control (A/C-PC) mode was utilized, with inspiratory pressure (Pi) set to 12 cmH₂O and positive end expiratory pressure (PEEP) set to 5 cmH₂O, and with a target Vt of 500 ml. The bias flow of all the ventilators was set to 2 L/min. The three nebulizers were the continuous jet nebulizer (c-JN), the inspiratory synchronized jet nebulizer (i-JN), and the vibrating mesh nebulizer (VMN). The five nebulizer positions were as follows: at the Y-piece (position 1) and 15 cm from the Y-piece (position 2) between the endotracheal tube and the Y-piece, at the Y-piece (position 3) and 15 cm from the Y-piece (position 4) in the inspiratory limb; and at the humidifier inlet (position 5). Aerosols were collected with a disposable filter placed at the simulated lung outlet (n = 3) and were measured by UV spectrophotometry (276 nm). The measurements were compared under different experimental conditions.

Results

The aerosol delivery of c-JN, i-JN, and VMN was 5.33 ± 0.49~11.12 ± 0.36%, 7.73 ± 0.76~13.75 ± 0.46% and 11.13 ± 56–30.2 ± 1.63%, respectively. The higher aerosol delivery: for c-JN~Positions 2 (10.95 ± 0.15%), fori-JN~Positions 1 or 2 (12.91 ± 0.88% or 13.45 ± 0.42%), for VMN~Positions 4(29.03 ± 1.08%); the lower aerosol delivery: for c-JN~Positions 1, 3 or 5, fori-JN~Positions 4 or 5, for VMN~Positions 5.

The highest aerosol delivery:For c-JN at Position 2 (10.95 ± .15%), for i-JN at Position 1 or 2 (12.91 ± .88% or 13.45 ± .42%), for VMN at Positions 4 (29. 03 ± 1.08%); the lower aerosol delivery: for c-JN at Positions 1, 3 or 5, for i-JN at Positions 4 or 5, for VMN at Positions 5. The highest aerosol deliveryof c-JN was lower than that of i-JN while the VMN was the highest (all P < .05). However, no differences were observed between the highest aerosol delivery with c-JN and the lowest aerosol delivery with i-JN. Similar results were found between the lowest aerosol delivery with VMN and the highest aerosol delivery with c-JN /i-JN in the Avea ventilator. There were no differences in the highest aerosol delivery of each nebulizer among the different ventilators (all p > 0.05).

Conclusion

During adult mechanical ventilation, the type and position of nebulizer influences aerosol delivery efficiency, with no differences between ventilators.

Indian Guidelines on Nebulization Therapy

Inhalational therapy, today, happens to be the mainstay of treatment in obstructive airway diseases (OADs), such as asthma, chronic obstructive pulmonary disease (COPD), and is also in the present, used in a variety of other pulmonary and even non-pulmonary disorders. Hand-held inhalation devices may often be difficult to use, particularly for children, elderly, debilitated or distressed patients. Nebulization therapy emerges as a good option in these cases besides being useful in the home care, emergency room and critical care settings. With so many advancements taking place in nebulizer technology; availability of a plethora of drug formulations for its use, and the widening scope of this therapy; medical practitioners, respiratory therapists, and other health care personnel face the challenge of choosing appropriate inhalation devices and drug formulations, besides their rational application and use in different clinical situations. Adequate maintenance of nebulizer equipment including their disinfection and storage are the other relevant issues requiring guidance. Injudicious and improper use of nebulizers and their poor maintenance can sometimes lead to serious health hazards, nosocomial infections, transmission of infection, and other adverse outcomes. Thus, it is imperative to have a proper national guideline on nebulization practices to bridge the knowledge gaps amongst various health care personnel involved in this practice. It will also serve as an educational and scientific resource for healthcare professionals, as well as promote future research by identifying neglected and ignored areas in this field. Such comprehensive guidelines on this subject have not been available in the country and the only available proper international guidelines were released in 1997 which have not been updated for a noticeably long period of over two decades, though many changes and advancements have taken place in this technology in the recent past. Much of nebulization practices in the present may not be evidence-based and even some of these, the way they are currently used, may be ineffective or even harmful. Recognizing the knowledge deficit and paucity of guidelines on the usage of nebulizers in various settings such as inpatient, out-patient, emergency room, critical care, and domiciliary use in India in a wide variety of indications to standardize nebulization practices and to address many other related issues; National College of Chest Physicians (India), commissioned a National task force consisting of eminent experts in the field of Pulmonary Medicine from different backgrounds and different parts of the country to review the available evidence from the medical literature on the scientific principles and clinical practices of nebulization therapy and to formulate evidence-based guidelines on it. The guideline is based on all possible literature that could be explored with the best available evidence and incorporating expert opinions. To support the guideline with high-quality evidence, a systematic search of the electronic databases was performed to identify the relevant studies, position papers, consensus reports, and recommendations published. Rating of the level of the quality of evidence and the strength of recommendation was done using the GRADE system. Six topics were identified, each given to one group of experts comprising of advisors, chairpersons, convenor and members, and such six groups (A-F) were formed and the consensus recommendations of each group was included as a section in the guidelines (Sections I to VI). The topics included were: A. Introduction, basic principles and technical aspects of nebulization, types of equipment, their choice, use, and maintenance B. Nebulization therapy in obstructive airway diseases C. Nebulization therapy in the intensive care unit D. Use of various drugs (other than bronchodilators and inhaled corticosteroids) by nebulized route and miscellaneous uses of nebulization therapy E. Domiciliary/Home/Maintenance nebulization therapy; public & health care workers education, and F. Nebulization therapy in COVID-19 pandemic and in patients of other contagious viral respiratory infections (included later considering the crisis created due to COVID-19 pandemic). Various issues in different sections have been discussed in the form of questions, followed by point-wise evidence statements based on the existing knowledge, and recommendations have been formulated.

In-Vitro Comparison of Single Limb and Dual Limb Circuit for Aerosol Delivery via Noninvasive Ventilation

BACKGROUND

The effect of single- and dual-limb circuits on aerosol delivery during noninvasive ventilation (NIV) in adult models is unclear.

METHODS

A noninvasive ventilator equipped with a single-limb circuit or an ICU ventilator equipped with a dual-limb circuit was connected to a simulated lung. Ventilator parameters were adjusted to maintain a tidal volume at ∼500 mL. Aerosol deposition with different placements of a vibrating mesh nebulizer and humidification conditions were compared. Additional experiments by using a non-vented mask or a vented mask were compared in the single-limb circuit only. Aerosol was collected by a disposable filter placed between the simulated lung and the head model (n = 3), and measured by ultraviolet spectrophotometry (276 nm).

RESULTS

The aerosol deposition varied between 4.12 ± 0.22% and 20.75 ± 0.95%. The greatest aerosol delivery during NIV when using a non-vented mask was found when a vibrating mesh nebulizer was placed between the mask and 15 cm from the exhalation port in the humidified single-limb circuit, and 15 cm from the Y-piece in the inspiratory limb of the humidified dual-limb circuit, and no significant difference of aerosol deposition was found between the two optimal positions (20.03 ± 1.48% vs 18.04 ± 0.93%, respectively; P =.042). There was no difference of aerosol delivery in dry versus humidified circuits, except when a vibrating mesh nebulizer was placed at the humidifier inlet in a dual-limb circuit. When using a vented mask, the aerosol deposition was poor (6.56 ± 0.41 ∼ 8.02 ± 0.39%), regardless of vibrating mesh nebulizer positions and humidification types.

CONCLUSIONS

During NIV, the aerosol delivery was optimal when a vibrating mesh nebulizer was placed between the non-vented mask and 15 cm from the exhalation port in the single-limb circuit or 15 cm from the Y-piece in the inspiratory limb of the dual-limb circuit; no significant difference was found between the two optimal placements. Humidification had little effect on aerosol delivery. Aerosol delivery was poor in the single-limb circuit with a vented mask.

The Use of Aerosolized Medications in Adult Intensive Care Unit Patients: A Prospective, Multicenter, Observational, Cohort Study

Background: Only limited data are available on the real-life clinical utilization of aerosolized medications in intensive care unit (ICU) patients. Exploring the utilization of aerosolized medications in the ICU may contribute to develop appropriate education and improve the quality of aerosol therapy. Methods: A 2-week, prospective, multicenter, observational, cohort study was conducted to record how the aerosolized medications were utilized in the Chinese ICUs, including indications, medications used in solo or combination, dosage, and side-effects in adult patients. Results: A total of 1006 patients from 28 ICUs were enrolled, of which 389 (38.7%) received aerosol therapy. The most common indications for aerosol therapy were difficulty in secretion management (23.1%) and chronic obstructive pulmonary disease exacerbation (18.5%). The combination of inhaled corticosteroids and short-acting muscarinic antagonist was the most commonly used medication (19.5%, 76/389). Ninety-two percent (358/389) of the patients did not have any side effects during aerosol therapy. More patients in the group with mechanical ventilation received bronchodilators than spontaneous breathing patients (81.3% vs. 55.5%, p < 0.001), and more patients who breathed spontaneously through a tracheostomy received mucus-regulating agents than other patients (70% vs. 37.9%, p = 0.004). Conclusion: In mainland China, more than one-third of adult ICU patients received aerosol therapy. Medications utilized during aerosol therapy were variable in patients with different respiratory support. To promote appropriate use of aerosolized medications, high-quality randomized, controlled trials and clinical guidance on aerosolized medication indications and dosing are needed to improve clinical outcomes.

The Clinical Practice and Best Aerosol Delivery Location in Intubated and Mechanically Ventilated Patients: A Randomized Clinical Trial

This randomized clinical trial (RCT) is aimed at exploring the best nebulizer position for aerosol delivery within the mechanical ventilation (MV) circuitry. This study enrolled 75 intubated and MV patients with respiratory failure and randomly divided them into three groups. The nebulizer position of patients in group A was between the tracheal tube and Y-piece. For group B, the nebulizer was placed at the inspiratory limb near the ventilator water cup (80 cm away from the Y-piece). For group C, the nebulizer was placed between the ventilator inlet and the heated humidifier. An indirect competitive enzyme-linked immunosorbent assay (ELISA) was used to measure salbutamol drug concentrations in serum and urine. The serum and urine salbutamol concentrations of the three groups were the highest in group B, followed by group C, and the lowest in group A. Serum and urine salbutamol concentrations significantly differed among the three groups (P < 0.05). It was found that the drug was statistically significant between group differences for groups B and A (P = 0.001; P = 0.002, respectively) for both serum and urine salbutamol concentrations. There were no significant differences observed among the other groups. It was found that the drug concentrations were the highest when the nebulizer was placed 80 cm away from the Y-piece, while the location between the tracheal tube and the Y-piece with the higher frequency of nebulizer placement was the location with the lowest drug concentration.