Feasibility of Administering a Bronchodilator Continuously via Vibrating Mesh Nebulizer and Syringe Pump During Mechanical Ventilation

Background:

Aerosolized bronchodilators (AB) are frequently administered via nebulizer (NEB) to treat episodes of bronchospasm. Lung model (LM) studies suggest that aerosol delivery during mechanical ventilation (MV) is suboptimal. Use of the Aerogen vibrating mesh nebulizer (VMN) allows administration of albuterol continuously through a syringe pump (SP) without the need of gas to power the NEB. We examined the interactions between electronic components to assess impact on rate of nebulization (RON) during MV.

Methods:

Pharmacy downloaded programming for albuterol 0.5%, 5mg/mL continuous into the Medfusion 4000 SP drug library. A 60 mL syringe was filled with 20 mL of saline (0.9%) to simulate albuterol 0.5%, 20 mL solution, and attached to the SP. The SP was set to dispense 15 mg/h in the first round and 20 mg/h for the second round of 4h testing. Fluid from the syringe was used to prime the SP tubing and 1 mL injected into the VMN reservoir to start nebulization. The control timer was set to continuous. The Servo-i (SV) mechanical ventilator was used for the study with a VMN to deliver AB to a LM. The SV mechanics were monitored at 1 h and post 4 h nebulization at different mg/h doses; tidal volume (V_T) - 0.45 mL, volume control (VC) - 12 breaths/min, peak airway pressure (P_aw) - 22 cm H₂O, plateau pressure (Pplat) - 14 cm H₂O, PEEP +8 cm H₂O. The VMN was inserted on the dry side of the Fisher & Paykel humidifier chamber. Acceptable MV functionality was verified by observation of the SV on board monitoring systems.

Results:

After completion of the studies, there were no significant performance issues with regard to RON on MV mechanics; V_T - 0.45 mL ± 0.08, P_aw - 22 ± 2 cm H₂O, Pplat - 14 ± 2 cm H₂O, PEEP - +8 cm H₂O, with no auto-PEEP, auto-cycling or changes to waveform graphics detected. The RON equal aerosolized drug volume delivered in mL/h; 15 mg/h = 3 mL/h and 20 mg/h = 4 mL/h. This study confirmed that 12 mL ± 1 was nebulized at 15 mg/h and 16 mL ± 1 was nebulized at 20 mg/h in 4h.

Conclusions:

This study demonstrated that continuous AB delivery via SP+MV is feasible. RON volume per hour were stable and drug dilution was not required which may improve effectiveness. Short term use of the SP (10–20 min) to administer AB may not be advantageous for delivering enough volume to optimize delivery. The interactions of different equipment did not have an undesirable effect on machinery functionality. Further study is needed to determine RON effect on deposition during MV.

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SP+VMN connected to dry side of HC