In Vitro Measurements of Spiriva Respimat Dose Delivery in Mechanically Ventilated Tracheostomy Patients.

Background: For patients with severe chronic obstructive pulmonary disease under invasive mechanical ventilation, medication for aerosol therapy is delivered through tracheostomy or endotracheal airways. Typically, these medications (such as bronchodilators) are long-acting formulations that are delivered through Soft Mist™ Inhalers (SMI), or Pressurized Metered-Dose Inhalers. The Respimat® SMI has been shown to have increased efficiency because of its slow and prolonged aerosol mist and has gained popularity in clinical settings. However, the Respimat was not designed for drug delivery through artificial airways. Therefore, there is a need for SMI adapters in intensive care for use in mechanical ventilator circuits. The purpose of this study was to evaluate the performance of a new Respimat adapter (ODAPT™ for mechanical ventilator [ODAPT MV]) for use in mechanical ventilator circuits which, in combination with a Pulmodyne T-piece adapter, allows use without interruption of the circuit in case of medication replacement. Methods: Tiotropium delivery to the lungs, using Respimat, was assessed using the ODAPT MV adapter within an in vitro setup, including a three-dimensional printed trachea model and a mechanical ventilator. Medication deposition and losses were investigated using two commonly used tracheostomy tube (TT) sizes (6 and 8 mm inner canula) for two flow rates (45 and 60 L/min) under different conditions (30%-50%. and 100% relative humidity [RH]). Medication delivery using the ODAPT MV adapter was compared with the RTC-26C in-line adapter under similar conditions (8 mm TT size, 100% RH at 45 L/min). Results: It was found that 7.1%-13.4% of the nominal dose (ND) was lost in the ODAPT MV adapter for different TT size, RH, and flow rates used. Higher losses were found in the inhaler's mouthpiece ranging from 15.7% to 29.1% ND. The percentage of the delivered medication reaching the lungs was determined to be 13.7%-18.5% ND delivered without significant differences between the experimental conditions tested. The ODAPT MV performed well compared with the RTC-26C under similar conditions (17.9% and 16.6% ND, respectively). Conclusion: The medication delivered through mechanical ventilation using the ODAPT MV adapter represents about one third the dose delivered directly through the Respimat SMI in vivo.

In vitro investigation of the Flusso™ Bypass adapter efficiency upon ventilator circuit disconnect in a clinical simulated environment.

RATIONALE: Mechanically ventilated patients must be disconnected from the ventilator during intra-facility transfers. Intentional and accidental circuit disconnections represent a potential hazard to patients (sudden collapse and re-expansion of the alveoli) as well as to clinical staff (exposure to patient's unfiltered exhalation). Therefore, avoiding abrupt circuit disconnections could better protect the patient's health and reduce or eliminate contamination risks around clinical staff. OBJECTIVE: The purpose of this in-vitro work was to investigate and evaluate the potential for environmental exposure of Nitric Oxide (NO, as an indicator of any contamination exposure) before and after implementing the novel Flusso™ Bypass adapter during the disconnect procedure of a mechanical ventilator system. METHODS: A mechanical ventilator delivering NO was connected to a breathing simulator with and without the Flusso™ Bypass adapter. The ambient NO concentration was measured when the circuit was briefly disconnected (3 s) during inhalation and exhalation. Both volume and pressure ventilation modes were used. MEASUREMENTS AND MAIN RESULTS: Disconnecting the standard ventilator circuit (pressure-controlled mode) without the Flusso™ Bypass adapter produced higher NO escape to the surroundings (compared with the volume-controlled mode), leading to a longer NO dissipation time. No ambient NO traces were detected when the Flusso™ adapter was used. CONCLUSION: The usage of the Flusso™ adapter drastically decreases the unwanted exposure among clinical staff dealing with potentially hazardous airborne biological aerosols emanating from the circuit. Avoiding abrupt disconnection in the ventilator circuit could reduce lung injuries and alveolar over distension and collapse.

Aerosolization of Zn-DTPA Decorporation Agent Using Jet and Ultrasonic Nebulizers.

BACKGROUND: Chelating agents such as diethylenetriamine pentaacetic acid (DTPA) can be used as a decorporation drug in the zinc (Zn) form to treat internal radioactive contamination after exposure to plutonium or americium in a nuclear accident. Although Zn-DTPA is normally administered intravenously, inhalation of Zn-DTPA in aerosol form is a better route for direct delivery to the lungs. This work investigates the feasibility of synthesizing Zn-DTPA from three common chemicals and aerosolizing it using a jet or ultrasonic nebulizer. METHODS: The particle size distribution (PSD) of this decorporation agent at different concentrations were tested in vitro using two different methods: inertial impaction and aerodynamic time of flight. The particles were generated using either a jet nebulizer or an ultrasonic nebulizer. Two parameters, namely the mass median aerodynamic diameter and the geometric standard deviation, were assessed to determine the PSD of the generated aerosols. These parameters were obtained for different concentrations of Zn-DTPA using both nebulizers. RESULTS AND CONCLUSIONS: Zn-DTPA was successfully synthesized for decorporation purposes. Aerosol particles within the inhalable range were successfully generated by both nebulizers from four different concentrations of Zn-DTPA. It was found that the medication concentration did not affect the PSD of Zn-DTPA. The ultrasonic nebulizer was observed to produce a slightly larger aerosol particle size and required slightly longer treatment periods to deliver an effective dose to the lungs when compared with the jet nebulizer. Both nebulizers can be sustainably run to administer the agent for effective decorporation treatment of a large population after any major nuclear accident.

Improving prediction of aerosol deposition in an idealized mouth using large-Eddy simulation.

Monodisperse aerosol deposition in an idealized mouth geometry with a relatively small inlet diameter (D (in) = 3.0 mm) was studied numerically using a standard Large Eddy Simulation (LES). A steady inhalation flow rate of Q = 32.2 L/min was used. Thousands of particles (2.5, 3.7, and 5.0 microm in diameter and rho (f) = 912.0 kg/m(3) density) were released separately in the computational domain and aerosol deposition was determined. The total aerosol deposition results in this idealized mouth were in relatively good agreement when compared with measured data obtained in separate experiments, showing considerable improvement over the standard RANS/EIM (Reynolds Averaged Navier-Stokes/Eddy Interaction Model) approach.