Differential Performance and Lung Deposition of Levofloxacin with Different Nebulisers Used in Cystic Fibrosis

We compared the performance and levofloxacin (Quinsair) lung deposition of three nebulisers commonly used in CF (I-Neb Advance, eFlow rapid, and LC Plus) with the approved nebuliser Zirela. The delivered dose, delivery rate, and aerosol particle size distribution (APSD) for each device were determined using the methods described in the Pharmacopeia. High-resolution computed tomography scans obtained from seven adult patients with mild CF were used to generate computer-aided, three-dimensional models of their airway tree to assess lung deposition using functional respiratory imaging (FRI). The eFlow rapid and the LC Plus showed poor delivery efficiencies due to their high residual volumes. The I-Neb, which only delivers aerosols during the inspiratory phase, achieved the highest aerosol delivery efficiency. However, the I-Neb showed the largest particle size and lowest delivery rate (2.9 mg/min), which were respectively associated with a high extrathoracic deposition and extremely long nebulisation times (>20 min). Zirela showed the best performance considering delivery efficiency (159.6 mg out of a nominal dose of 240 mg), delivery rate (43.5 mg/min), and lung deposition (20% of the nominal dose), requiring less than 5 min to deliver a full dose of levofloxacin. The present study supports the use of drug-specific nebulisers and discourages the off-label use of general-purpose devices with the present levofloxacin formulation since subtherapeutic lung doses and long nebulisation times may compromise treatment efficacy and adherence.

"Less is more": a dose-response account of intranasal oxytocin pharmacodynamics in the human brain

Intranasal oxytocin is attracting attention as a potential treatment for several brain disorders due to promising preclinical results. However, translating findings to humans has been hampered by remaining uncertainties about its pharmacodynamics and the methods used to probe its effects in the human brain. Using a dose-response design (9, 18 and 36 IU), we demonstrate that intranasal oxytocin-induced changes in local regional cerebral blood flow (rCBF) in the amygdala at rest, and in the covariance between rCBF in the amygdala and other key hubs of the brain oxytocin system, follow a dose-response curve with maximal effects for lower doses. Yet, the effects on local rCBF might vary by amygdala subdivision, highlighting the need to qualify dose-response curves within subregion. We further link physiological changes with the density of the oxytocin receptor gene mRNA across brain regions, strengthening our confidence in intranasal oxytocin as a valid approach to engage central targets. Finally, we demonstrate that intranasal oxytocin does not disrupt cerebrovascular reactivity, which corroborates the validity of haemodynamic neuroimaging to probe the effects of intranasal oxytocin in the human brain. DATA AVAILABILITY: Participants did not consent for open sharing of the data. Therefore, data can only be accessed from the corresponding author upon reasonable request.

Two-minute tidal breathing methacholine bronchial challenge: Comparison of two jet nebulisers

BACKGROUND

The American Thoracic Society (ATS) guideline for methacholine challenge testing (MCT) recommended using the English Wright (EW) nebuliser. However, other brands of nebulisers are also indicated to be acceptable for this technique, but further validation of nebuliser performance is recommended.

OBJECTIVE

To compare the methacholine provocation concentration causing a 20% fall in forced expiratory volume in 1 second (PC₂₀ -FEV₁ ) measured by using EW nebuliser and DV 646 nebuliser.

METHODS

Subjects were randomly assigned to undergo 2-min tidal breathing methacholine challenge with either EW or DV 646 nebuliser on two separate days, which were at least 24 hours but not more than 7 days apart. The above procedure was repeated for each subject in 1 month, but the nebulisers were selected in a reverse order.

RESULTS

The study includes 15 mild and stable asthmatic patients. The geometric means (SD) of methacholine PC₂₀ measured with using EW and DV 646 nebulisers were 1.82 (6.38) mg/mL versus 0.83 (1.82) mg/mL, respectively in the initial two visits and 2.56 (6.29) mg/mL versus 0.78 (1.40) mg/mL in the following two visits (both P < 0.05). There are well correlations between PC20-EW1 and PC20-EW2 (r = 0.99, P < 0.01), PC20-DV1 and PC20-DV2 (r = 0.88, P < 0.01), and between PC20-EW1 and PC20-DV1 (r = 0.91, P < 0.01), PC20-EW2 and PC20-DV2 (r = 0.78, P < 0.01).

CONCLUSIONS

PC₂₀ -FEV₁ measured by using the two conventional jet nebulisers was both repeatable and the results were highly correlated.

Evaluation of Aerosol Therapy during the Escalation of Care in a Model of Adult Cystic Fibrosis

Lung disease is the main cause of morbidity and mortality in cystic fibrosis (CF). CF patients inhale antibiotics regularly as treatment against persistent bacterial infections. The goal of this study was to investigate the effect of clinical intervention on aerosol therapy during the escalation of care using a bench model of adult CF. Droplet size analysis of selected antibiotics was completed in tandem with the delivered aerosol dose (% of total dose) assessments in simulations of various interventions providing oxygen supplementation or ventilatory support. Results highlight the variability of aerosolised dose delivery. In the homecare setting, the vibrating mesh nebuliser (VMN) delivered significantly more than the jet nebuliser (JN) (16.15 ± 0.86% versus 6.51 ± 2.15%). In the hospital setting, using VMN only, significant variability was seen across clinical interventions. In the emergency department, VMN plus mouthpiece (no supplemental oxygen) was seen to deliver (29.02 ± 1.41%) versus low flow nasal therapy (10 L per minute (LPM) oxygen) (1.81 ± 0.47%) and high flow nasal therapy (50 LPM oxygen) (3.36 ± 0.34%). In the ward/intensive care unit, non-invasive ventilation recorded 19.02 ± 0.28%, versus 22.64 ± 1.88% of the dose delivered during invasive mechanical ventilation. These results will have application in the design of intervention-appropriate aerosol therapy strategies and will be of use to researchers developing new therapeutics for application in cystic fibrosis and beyond.

Susceptibility of the Mycobacterium abscessus complex to drying: Implications for nebulizer hygiene in patients with cystic fibrosis

Background

Nebulizer hygiene and care is important in cystic fibrosis (CF) to minimize device contamination from bacteria, including nontuberculous mycobacteria (NTMs). Most nebulizer manufacturers recommend nebulizer drying, however there is little evidence to understand how nebulizer drying affects NTM survival.

Methods

Mycobacterium abscessus subsp. massiliense (n = 2), M. abscessus subsp. bolletii (n = 2), and M. abscessus subsp. abscessus (n = 2) were evaluated for their ability to survive simulated drying conditions associated with routine nebulizer care. Bacterial inocula (circa. 10⁷ colony-forming units) were added to plastic and allowed to dry to completeness for 24 h, employing passive and active drying.

Results

NTM isolates of all subspecies could be recovered from all passive and active drying experiments, both in diluent and in sterile sputum, following drying (24 h). There was no combination of drying or physiology that supported NTM cell death, and there was no difference in observed survival with the three species of M. abscessus examined.

Conclusion

This study indicates that drying, either passively or actively, for 24 h at room temperature, is unable to eradicate all M. abscessus organisms from dry plastic surfaces, even in the presence of residual sputum contamination. Whilst drying may be advantageous for nebulizer performance, it should not be regarded as an absolute control for the elimination of NTM organisms. With nebulizer hygiene, NTM organisms would be able to survive on a nebulizer following drying for 24 h, which has not undergone any formal disinfection protocol. Therefore, for NTM eradication from washed nebulizers, CF patients should therefore seek an effective alternative control to drying for NTM eradication, i.e., heat disinfection in baby bottle disinfectors. CF patients and health-care professionals should not rely solely on nebulizer drying to achieve NTM eradication.

Management of severe bronchiolitis: impact of NICE guidelines

OBJECTIVE

To understand the impact of the National Institute for Health and Care Excellence (NICE) bronchiolitis guidelines on the management of children referred to paediatric intensive care unit (PICU) with bronchiolitis.

DESIGN AND SETTING

Data were collected on all children referred to a regional PICU transport service with the clinical diagnosis of bronchiolitis during the winter prior to the NICE consultation period (2011-2012) and during the winter after publication (2015-2016). Management initiated by the referring hospital was assessed.

RESULTS

There were 165 infants referred with bronchiolitis in epoch 1 and 187 in epoch 2. Nebuliser use increased from 28% in epoch 1 to 53% in epoch 2. Increased use of high-flow nasal cannula oxygen and reduction in continuous positive airway pressure use were observed. The use of antibiotics did not change between epochs.

CONCLUSION

The use of nebulised therapies has increased in the management of severe bronchiolitis despite national guidance to the contrary.

Structure reactivity relationship in the accelerated formation of 2,3-diarylquinoxalines in the microdroplets of a nebuliser

Competition experiments in which 1,2-phenylenediamine, C₆H₄(NH₂)₂, condenses with equimolar quantities of benzil, (C₆H₅CO)₂, and a 3,3'- or 4,4'-disubstituted benzil (XC₆H₄CO)₂ (X = F, Cl, Br, CH₃ or CH₃O) to form a mixture of 2,3-diphenylquinoxaline and the corresponding 2,3-diarylquinoxaline (Ar = XC₆H₄) in the microdroplets produced in a nebuliser allow a Hammett relationship with a ρ value of 1.8₅ to be developed for this accelerated condensation in the nebuliser. This structure reactivity relationship reveals that an appreciable amount of negative charge builds up on the carbon of the carbonyl group of the benzil during the rate-limiting step of the reaction, thus confirming that this process involves nucleophilic addition of the 1,2-phenylenediamine to the benzil. In general, the presence of an electron donating substituent, particularly in the 4 and 4' positions, in the benzil retards the reaction, whereas an electron attracting substituent, especially in the 3 and 3' position, accelerates it.

Nebuliser cleaning and disinfection practice in the home among patients with cystic fibrosis

Background

Nebulised delivery of different classes of drugs is of fundamental importance in therapeutic regimens relating to both the management of disease progression in cystic fibrosis disease and its associated complications. The aim of this study was to determine if current nebuliser hygiene practices in the home environment by paediatric and adult cystic fibrosis populations are appropriate to ensure appropriate infection control and prevention measures have been addressed.

Methods

An Audit Questionnaire Study was completed with adult cystic fibrosis patients (n=20) or with parents of cystic fibrosis children (n=24), through a healthcare professional interview on a one-to-one basis, during either a home visit or during patient/parent attendance at cystic fibrosis clinic.

Results

Hygienic practices relating to nebuliser care varied, with paediatric carers more likely to clean and disinfect their devices. This study suggests there is much variation and confusion with regard to how to clean and disinfect nebulisers, as well as who is responsible for delivering this advice.

Conclusion

The adult cystic fibrosis community in particular needs to be educated on practicalities associated with nebuliser hygiene and the reasons why this is important. Furthermore, to date there is a lack of a universally recommended guideline suitable for all types of cystic fibrosis nebulisers that all relevant pharmaceutical manufacturers advocate.

Pilot study to quantify the time to clear dexamethasone from plasma and urine of adult horses following a single nebulisation

OBJECTIVE

To quantify the time to clear dexamethasone from plasma and urine of horses following a single nebulisation.

DESIGN

Experimental using six Standardbred mares.

METHODS

Dexamethasone sodium phosphate (0.04 mg/kg) diluted in 0.9% sodium chloride was administered as an aerosol using a Flexineb E2® nebuliser. Blood samples (0, 2, 4, 6, 8, 10, 12, 24, 32, 48, 72 and 96 h) and urine samples (0, 1, 4, 8, 24, 32, 48, 72 and 96 h) were collected for analysis using liquid chromatography mass spectrometry.

RESULTS

Maximum plasma concentrations (t_max ) were reached by the earliest detection point (2 h) after nebulisation (0.6-1.8 ng/mL), but was no longer detectable at 48 h. However, in one horse 0.1 ng/mL was found at 96 h after three consecutive readings of 0 ng/mL. The t_max in urine was reached by the earliest collection point (1 h) after nebulisation (3.2-23.8 ng/mL), but was no longer present in urine at 72 h in five horses, while detectable levels (0.1 ng/mL) were still present at 96 h in one horse.

CONCLUSIONS

A single dose of 0.04 mg/kg of DSP administered as an aerosol through a FlexinebE2® mask was no longer detectable in blood at 48 h in six horses tested, but one horse returned a reading of 0.1 ng/mL at 96 h after having no detectable levels. Dexamethasone was not detectable in urine at 72 h in five horses but was detectable at a low concentration (0.1 ng/mL) at 96 h in one horse.

Investigation of Fugitive Aerosols Released into the Environment during High-Flow Therapy

BACKGROUND

Nebulised medical aerosols are designed to deliver drugs to the lungs to aid in the treatment of respiratory diseases. However, an unintended consequence is the potential for fugitive emissions during patient treatment, which may pose a risk factor in both clinical and homecare settings.

METHODS

The current study examined the potential for fugitive emissions, using albuterol sulphate as a tracer aerosol during high-flow therapy. A nasal cannula was connected to a head model or alternatively, a interface was connected to a tracheostomy tube in combination with a simulated adult and paediatric breathing profile. Two aerodynamic particle sizers (APS) recorded time-series aerosol concentrations and size distributions at two different distances relative to the simulated patient.

RESULTS

The results showed that the quantity and characteristics of the fugitive emissions were influenced by the interface type, patient type and supplemental gas-flow rate. There was a trend in the adult scenarios; as the flow rate increased, the fugitive emissions and the mass median aerodynamic diameter (MMAD) of the aerosol both decreased. The fugitive emissions were comparable when using the adult breathing profiles for the nasal cannula and tracheostomy interfaces; however, there was a noticeable distinction between the two interfaces when compared for the paediatric breathing profiles. The highest recorded aerosol concentration was 0.370 ± 0.046 mg m-3 from the tracheostomy interface during simulated paediatric breathing with a gas-flow rate of 20 L/min. The averaged MMAD across all combinations ranged from 1.248 to 1.793 µm by the APS at a distance of 0.8 m away from the patient interface.

CONCLUSIONS

Overall, the results highlight the potential for secondary inhalation of fugitive emissions released during simulated aerosol treatment with concurrent high-flow therapy. The findings will help in developing policy and best practice for risk mitigation from fugitive emissions.

Investigation of the Quantity of Exhaled Aerosols Released into the Environment during Nebulisation

BACKGROUND

Secondary inhalation of medical aerosols is a significant occupational hazard in both clinical and homecare settings. Exposure to fugitive emissions generated during aerosol therapy increases the risk of the unnecessary inhalation of medication, as well as toxic side effects.

METHODS

This study examines fugitively-emitted aerosol emissions when nebulising albuterol sulphate, as a tracer aerosol, using two commercially available nebulisers in combination with an open or valved facemask or using a mouthpiece with and without a filter on the exhalation port. Each combination was connected to a breathing simulator during simulated adult breathing. The inhaled dose and residual mass were quantified using UV spectrophotometry. Time-varying fugitively-emitted aerosol concentrations and size distributions during nebulisation were recorded using aerodynamic particle sizers at two distances relative to the simulated patient. Different aerosol concentrations and size distributions were observed depending on the interface.

RESULTS

Within each nebuliser, the facemask combination had the highest time-averaged fugitively-emitted aerosol concentration, and values up to 0.072 ± 0.001 mg m-3 were recorded. The placement of a filter on the exhalation port of the mouthpiece yielded the lowest recorded concentrations. The mass median aerodynamic diameter of the fugitively-emitted aerosol was recorded as 0.890 ± 0.044 µm, lower the initially generated medical aerosol in the range of 2⁻5 µm.

CONCLUSIONS

The results highlight the potential secondary inhalation of exhaled aerosols from commercially available nebuliser facemask/mouthpiece combinations. The results will aid in developing approaches to inform policy and best practices for risk mitigation from fugitive emissions.

Development of a patient passport in asthma management

This article outlines the development, testing and evaluation of an asthma patient passport (APP). The APP was designed specifically for patients with severe and difficult-to-manage asthma. This patient group tends not to access emergency services when needed, potentially putting life at risk. These individuals prefer to self-manage rather than expose themselves to feelings of vulnerability in the emergency department (ED). The aims of the project were to save lives by ensuring these patients attend the ED, to improve patient experience in the ED and to assist healthcare professionals in their clinical decision making, enabling them to deliver appropriate and individualised emergency treatment.

Lung deposition of inhaled alpha-1-proteinase inhibitor (alpha 1-PI) - problems and experience of alpha1-PI inhalation therapy in patients with hereditary alpha1-PI deficiency and cystic fibrosis

Alpha-1-proteinase inhibitor (α1-PI) is the most relevant protease inhibitor in the lung. Patients with hereditary deficiency of α1-PI suffer from an impaired hepatic synthesis of α1-PI in the liver and in consequence an insufficient concentration of the protease inhibitor in the lung followed by development of lung emphysema due to an impaired protease antiprotease balance and a local relative excess of neutrophil elastase (NE). In contrast, patients with cystic fibrosis (CF) are characterised by a normal synthesis of α1-PI and a severe pulmonary inflammation with a strong excess of NE in the lung followed by progressive loss of lung function. In principle, both patient groups may benefit from an augmentation of α1-PI. Intravenous augmentation, which is established in patients with α1-PI deficiency only, is very expensive, subject to controversial discussions and only about 2% of the administered protein reaches lung interstitium. Inhalation of α1-PI may serve as an alternative to administer high α1-PI doses into the lungs of both patient groups to restore the impaired protease antiprotease balance and to diminish the detrimental effects of NE. However, prerequisites of this therapy are the reproducible administration of sufficient doses of active α1-PI into the lung without adverse effects. In our review we describe the results of studies investigating the inhalation of α1-PI in patients with α1-PI deficiency and CF. The data demonstrate the feasibility of α1-PI inhalation for restoration of the impaired protease antiprotease balance, attenuation of the inflammation and neutralisation of the excess activity of NE. Likely, inhalation of α1-PI serves as cheaper and more convenient therapy than intravenous augmentation. However, inhalation will be further optimised by use of novel nebulisers and optimised breathing techniques.

Lung delivery of non-CFC salbutamol via small volume metal spacer and large volume plastic spacer devices compared with an open vent jet nebulizer

AIMS

To compare the lung delivery of salbutamol from a commonly used constant output open vent jet nebuliser (Sidestream) with use of both a conventional large volume plastic spacer (Volumatic) and a novel small volume metal spacer (NebuChamber). This was assessed using the early lung absorption profile of salbutamol over the first 20 min after inhalation.

METHODS

Twelve healthy volunteers were studied in a randomized single (investigator) blind crossover design. Single 1200 microg nominal doses salbutamol from a CFC-free metered-dose inhaler (12 sequential 100 microg puffs of Airomir) were delivered via the Volumatic and NebuChamber spacers. A single 1200 microg nominal dose of salbutamol was given as a 4 ml fill volume from a Sidestream nebuliser with mouthpiece. Mouth rinsing was performed after each drug sequence. Plasma salbutamol was measured at 5, 10, 15 and 20 min after the last dose of each inhalation sequence, with calculation of maximal concentration (Cmax) and average concentration over 20 min (C[av]). Systemic beta2-responses were measured as plasma potassium, tremor and heart rate.

RESULTS

Both the Volumatic and the NebuChamber spacers produced significantly greater salbutamol concentration than the Sidestream nebuliser. For C(av) this amounted to a 7.34-fold difference (95%CI 5.31 to 9.38) between Volumatic vs Sidestream, and a 7.04-fold difference (95%CI 4.91 to 9.17) for NebuChamber vs Sidestream. Similar differences were found for the extrapulmonary beta2-responses. There were no significant differences in either salbutamol concentration or extrapulmonary beta2-responses between the Volumatic and NebuChamber spacers.

CONCLUSIONS

We found that, in vivo, both the Volumatic and the NebuChamber spacers produced seven-fold greater lung delivery of salbutamol than the Sidestream nebuliser when comparing microgram equivalent nominal doses, in terms of the early lung absorption profile.