Comparison of Lung Deposition of Amikacin by Intrapulmonary Percussive Ventilation and Jet Nebulization by Urinary Monitoring

[Pneumatic instrumental airway clearance techniques: Description, settings and indications]

Airway clearance techniques aim to eliminate excess of bronchopulmonary secretions. Common airway clearance methods involve manual techniques or the use of (oscillatory) positive expiratory pressure systems. In some clinical situations, these techniques may be ineffective, and the physiotherapist will require pneumatic instrumental support. Unfortunately, these devices are expensive and burdensome. Moreover, as their utilization requires specialized expertise, they are seldom used by practitioners. This article describes the pneumatic instrumental supports mainly used in France for airway clearance techniques currently available. We explain their key characteristics, how they function, and their basic settings according to different indications.

Low-Frequency Intrapulmonary Percussive Ventilation Increases Aerosol Penetration in a 2-Compartment Physical Model of Fibrotic Lung Disease

In patients with fibrotic pulmonary disease such as idiopathic pulmonary fibrosis (IPF), inhaled aerosols deposit mostly in the less affected region of the lungs, resulting in suboptimal pharmacokinetics of airway-delivered treatments. Refinement of aerosol delivery technique requires new models to simulate the major alterations of lung physiology associated with IPF, i.e., heterogeneously reduced lung compliance and increased airway caliber. A novel physical model of the respiratory system was constructed to simulate aerosol drug delivery in spontaneously breathing (negative pressure ventilation) IPF patients. The model comprises upper (Alberta ideal throat) and lower airway (plastic tubing) models and branches into two compartments (Michigan lung models) which differ in compliance and caliber of conducting airway. The model was able to reproduce the heterogeneous, compliance-dependent reduction in ventilation and aerosol penetration (using NaF as a model aerosol) seen in fibrotic lung regions in IPF. Of note, intrapulmonary percussive ventilation induced a 2-3-fold increase in aerosol penetration in the low-compliance/high airway caliber compartment of the model, demonstrating the responsiveness of the model to therapeutic intervention.

The effect of intrapulmonary percussive ventilation in pediatric patients: A systematic review

BACKGROUND

Intrapulmonary percussive ventilation (IPV) is frequently used in clinical practice to enhance sputum evacuation and lung recruitment. However, the evidence in different respiratory pathologies, especially in children, is still lacking. This systematic review aims to enlist the effectiveness of IPV as an airway clearance technique in pediatric patients.

DATA SOURCES

A systematic literature search was performed in PubMed, Web of Science, and the Cochrane Library databases.

STUDY SELECTION

Studies were included if the subjects suffered from a respiratory disease requiring airway clearance and the mean age of the sample was <18 years. After screening, nine articles remained for further analysis.

RESULTS

Three of the nine articles examined patients with cystic fibrosis (CF). No significant differences in lung function or expectorated mucus were found compared to conventional chest physiotherapy. On the other hand, significant beneficial results were found for the treatment or prevention of atelectasis in non-CF patients using IPV. Similar results were seen when comparing therapies for neuromuscular/neurological patients. One study found that IPV reduced hospital stay and improved the clinical status of children with acute bronchiolitis compared to no physiotherapy. Severe adverse events did not occur in the included studies.

CONCLUSION

A limited number of studies investigated IPV in the pediatric population. Despite the heterogeneity across the studies and the small sample sizes, the results seem promising. IPV is suggested to be a safe and effective alternative for airway clearance. Future research is required to confirm these results and to further analyze the possible benefits in different respiratory pathologies.

Influence of Tracheostomy on Lung Deposition in Spontaneously Breathing Patients

BACKGROUND

Nebulized drugs are frequently administrated through tracheostomy in clinical routine. So far, the amount of drug deposited into the lung in these patients remains unknown. The aim of our pharmacokinetic study was to compare lung delivery of amikacin in the same subjects in two settings: spontaneously breathing through a tracheostomy and through the mouth.

METHODS

Lung delivery was measured by amikacin urinary drug concentration in nine patients who were transitory tracheostomized for the need of a head and neck oncologic surgery. Patients performed two nebulization sessions: with a mouthpiece (MB) and through tracheostomy (TB) using a adapted jet nebulizer (Sidestream^®).

RESULTS AND CONCLUSION

Lung delivery was similar with the two conditions of nebulization (6.5 ± 2.5% vs. 6.3 ± 2.0% of the nominal mass of amikacin, respectively, for MB and TB; p = 0.95). Duration of nebulization was also comparable (19.7 ± 1.6 vs. 20.1 ± 1.8 min, respectively, for mouth and tracheostomy breathing; p = 0.307). The half-life and elimination rate constant were not different between the two settings. We conclude that nebulized therapy can be administered in spontaneously breathing tracheostomized adults patients, with a similar amount of drug delivered to the lung compared with spontaneously mouth breathing patients.

Use of laser microdissection in the analysis of renal-infiltrating T cells in murine lupus

Objective

To clarify the role of T cells in kidney pathology of three widely used murine lupus models.

Material and methods

Cells infiltrating the glomeruli and perivascular areas in MRL/lpr (n = 10 female), NZB× NZW F1 (B/W F1) (n = 9 female), and BXSB (n = 10 male) mice were captured by laser microdissection (LMD). Samples were subjected to nested reverse transcription polymerase chain reaction (RT-PCR) with primers specific to β-actin, T-cell receptor β chain (TCR-Cβ), interleukin (IL)-10, IL-13, IL-17, and interferon-g (IFN-γ). Frozen sections of lesions were also stained immunohistochemically for tissue and cellular characterization.

Results

T cells infiltrating the glomeruli and perivascular areas predominantly produced IFN-γ, IL-13, and IL-17 in MRL/lpr, B/W F1, and BXSB mice, with IL-17 expression in glomeruli of BXSB mice being significantly lower than that of MRL/lpr and B/W F1 mice. IL-10 was detected only in the perivascular areas of MRL/lpr and B/W F1 mice and not in glomeruli isolates. Immunohistochemical staining revealed positive for the expression of Thy-1, CD4, CD8, and B220 in glomeruli and perivascular areas from all three strains of mice.

Conclusions

Cytokine balance in murine SLE is complex and cannot be attributed simply to the balance between Th1 and Th2 cells. Th17 cells may play a critical role in disease pathology, possibly with greater contribution toward disease progression in MRL/lpr and B/W F1 mice than in BXSB mice. Furthermore, these findings lend support to the concept that different molecular mechanisms underlie glomerulonephritis as compared to vasculitis.

Aerosol delivery to the lung is more efficient using an extension with a standard jet nebulizer than an open-vent jet nebulizer

BACKGROUND

Open-vent jet nebulizers are frequently used to promote drug deposition in the lung, but their clinical efficacy and indications are not clear. Our study compared lung deposition of amikacin using two different configurations of a jet nebulizer (Sidestream(®)): one vented (N1) and one unvented with a corrugated piece of tubing (N2).

METHODS

In vitro nebulizer performance was assessed by laser diffraction and filtering. Lung delivery was evaluated by scintigraphy in baboons as a child model, and by amikacin urinary drug concentration in seven healthy spontaneously breathing volunteers. Subjects were randomly assigned to the two nebulizer systems (N1 and N2).

RESULTS AND CONCLUSIONS

In vitro results showed a higher efficiency of N2 than N1 in terms of lung deposition prediction (95±3 mg vs. 70±0 mg; p<0.0001). Radioactivity deposition in the baboons' lungs was lower with N1 than with N2 (1.8% vs. 4.7% of nebulizer charge; p<0.05). The total daily amount of amikacin urinary excretion was lower with N1 than with N2 (29.5 mg vs. 40.1 mg; p<0.01). Conversely, in vivo drug output rate was higher with N1 than with N2 (3.1 mg/min vs. 2.2 mg/min; p<0.05). Using a corrugated piece of tubing with standard jet nebulizers delivers higher doses to the lungs than open-vent jet nebulizers. The open-vent jet nebulizer might be recommended for rapid administration of a lower dose to the lungs and the standard jet nebulizer with corrugated piece of tubing for a higher dose in the lungs.

Aerosol delivery through tracheostomy tubes: an in vitro study

BACKGROUND

Our study investigated the influence of the cannula's inner diameter (ID) and of its removal on the expected respiratory dose of amikacin, using three different jet nebulizer configurations (Sidestream(®)): vented (N1), unvented with a piece of corrugated tubing attached to the expiratory limb of the T attachment (N2), and unvented alone (N3).

METHODS

The jet nebulizer was filled with amikacin (500 mg/4 mL) and was attached to the tracheostomy tube. A lung model simulating spontaneous breathing was connected to the tracheostomy tube. A filter was connected between the nebulizer and the tracheostomy tube to measure the inhaled dose, and between the tracheostomy tube and the lung model to measure the respiratory dose. Different cannula IDs were tested (6.5, 8, 8.5, and 10 mm), and aerosol lost in the cannulas was determined.

RESULTS AND CONCLUSIONS

Respiratory dose varied between 96±1 mg and 44±3 mg, with higher values observed with N2. The aerosol lost in the cannula was significant and represented up to 63% of the inhaled dose. There was a negative correlation between the cannula's ID and the aerosol lost in the cannula. After removal of the internal cannula, an increase in the respiratory dose of up to 31.3% was observed. We recommend removing the inner tracheostomy cannula to nebulize a larger amount of drug through a tracheostomy tube. Among the three jet nebulizer configurations studied, we recommend the unvented one with a piece of corrugated tubing attached to the expiratory limb of the T attachment.

Aerosol therapy in patients receiving noninvasive positive pressure ventilation

In selected patients, noninvasive positive pressure ventilation (NIPPV) with a facemask is now commonly employed as the first choice for providing mechanical ventilation in the intensive care unit (ICU). Aerosol therapy for treatment of acute or acute-on-chronic respiratory failure in this setting may be delivered by pressurized metered-dose inhaler (pMDI) with a chamber spacer and facemask or nebulizer and facemask. This article reviews the host of factors influencing aerosol delivery with these devices during NIPPV. These factors include (1) the type of ventilator, (2) mode of ventilation, (3) circuit conditions, (4) type of interface, (5) type of aerosol generator, (6) drug-related factors, (7) breathing parameters, and (8) patient-related factors. Despite the impediments to efficient aerosol delivery because of continuous gas flow, high inspiratory flow rates, air leaks, circuit humidity, and patient-ventilator asynchrony, significant therapeutic effects are achieved after inhaled bronchodilator administration to patients with asthma and chronic obstructive pulmonary disease. Similarly to invasive mechanical ventilation, careful attention to the technique of drug administration is required to optimize therapeutic effects of inhaled therapies during NIPPV. Assessment of the patient's ability to tolerate a facemask, the level of respiratory distress, hemodynamic status, and synchronization of aerosol generation with inspiratory airflow are important factors contributing to the success of aerosol delivery during NIPPV. Further research into novel delivery methods, such as the use of NIPPV with nasal cannulae, could enhance the efficiency, ease of use, and reproducibility of inhalation therapy during noninvasive ventilation.

Effect of continuous positive airway pressure combined to nebulization on lung deposition measured by urinary excretion of amikacin

Continuous positive airway pressure (CPAP) is frequently used in patients attending emergency units. Its combination with nebulization is sometimes necessary in those patients presenting with a CPAP dependency.

STUDY OBJECTIVE

To compare lung deposition of amikacin delivered by a classical jet nebulizer (SideStream; Medic-Aid; West Sussex, UK) used alone (SST) or coupled to a CPAP device (Boussignac; Vygon; Belgium).

METHOD

Amikacin (1g) was nebulized with both devices in six healthy subjects during 5 min on spontaneous breathing. A 1-week wash-out period between each nebulization was applied. Lung deposition was indirectly assessed by urinary monitoring of excreted amount of amikacin.

RESULTS

Total daily amount of amikacin excreted in the urine was significantly lower with CPAP than with SST (1.97% initial dose versus 4.88% initial dose, p<0.001) with a corresponding mean ratio CPAP/SST of 0.41. The residual amount of amikacin in the nebulizer was higher with CPAP than with SST (607 mg versus 541 mg) but the difference was not significant (p=0.35).

CONCLUSION

These data suggest that the amount of amikacin delivered to healthy lungs is 2.5-fold lower with CPAP than with SST for the same nebulization time and that the nebulization time when using CPAP should be increased to reach the same amount of drug delivered with a classical jet nebulizer.

Recently published papers: the Jekyll and Hyde of oxygen, neuromuscular blockade and good vibrations?

This issue's recently published papers commentary takes a long hard look at the surprisingly topically issue of oxygen. To give a balanced perspective, topical ventilatory studies are also discussed.