Laboratory Study To Evaluate A Pressurized Metered Dose Inhaler With Valved Holding Chamber (Pmdi Plus Vhc) Use Scenario In Covid-19 Situation Where Pmdis In Short Supply

Patients infected with COVID-19 and admitted to hospital often require inhaled bronchodilator therapy to manage breathlessness. US hospitals are considering optimal ways to deliver such medication with pMDIs in short supply;the inhaler segregated from the patient allowing for reuse elsewhere without risk of contamination. In response to questions from hospitals, this laboratory study was undertaken to assess a protocol being considered in a specific facility. The pMDI (Ventolin{, 100 μg salbutamol) was actuated once into a VHC (AeroChamber Plus Flow-Vu), simulating use at the medication cart in a hospital hallway. The inhaler was removed and the pMDI adapter port of the VHC covered. 10s elapsed before connecting the VHC mouthpiece to a vacuum via an electrostatic filter to collect the suspended aerosol at 28.3 L/min. This delay simulated the time to enter patient room, and have patient inhale the salbutamol. Two, three and four rapid actuations (1-s apart) into the VHC prior to administration were also simulated. The mass of salbutamol was determined by HPLC-spectrophotometry. Salbutamol recovered (per actuation) from the filter for one to four actuations was 18 ± 7μg;13 ± 1μg;6 ± 1μg;and 5 ± 1μg respectively, confirming that the per-label practice of actuating and inhaling one puff at a time is the most efficient delivery method. For this specific and off label delivery scenario though, the maximum amount delivered as a single dose was achieved following two rapid actuations and as such can be considered optimal. Less than, or more than two actuations resulted in lower total delivery of salbutamol.