Lung Deposition of 99mTc-Radiolabeled Albuterol Delivered through a Pressurized Metered Dose Inhaler and Spacer with Facemask or Mouthpiece in Children with Asthma

Abstract

Background: Research on the use of a pressurized metered dose inhaler (pMDI) with spacer (pMDI/spacer) in children has indicated oral inhalation via the spacer mouthpiece is more efficient than the combination of oral and nasal inhalation that occurs when a pMDI/spacer is used with a facemask. Changes in pMDI formulations and developments in spacer and facemask designs have highlighted the need for new comparative studies of spacer use, particularly focusing on the age at which children can be taught to transition from use of a pMDI/spacer with facemask to use of the spacer mouthpiece. Methods: Twelve children aged 3–5 years (7 males) with stable asthma were recruited. Of these, 10 children (6 males) completed both arms of the study. A transmission scan of each compliant subject was taken using a 37 MBq 99mTc flood source. Actuations (2–3) of a 99mTc-radiolabeled albuterol pMDI were administered through an antistatic spacer (OptiChamber Diamond) via either a facemask (medium LiteTouch facemask), or the spacer mouthpiece. The subject's inhalation pattern was simultaneously recorded using a pMDI Datalogger, and narrative data relating to tolerance and compliance were documented. Anterior and posterior planar scintigraphic scans were taken immediately after aerosol administration.Results: Mean (SD) lung deposition (% total dose) was 18.1 (9.1)% with the facemask and 22.5 (7.9)% with the spacer mouthpiece (p>0.05). Peripheral lung deposition (expressed as peripheral:central (P:C) ratio) was higher in 7 out of 10 children with the facemask compared with the spacer mouthpiece: 1.3 (0.26) vs. 1.2 (0.35); (p=0.11). Head and neck deposition was higher with use of the facemask compared with the spacer mouthpiece: 19.7 (10.6)% vs. 10.8 (5.3)% (p=0.011). Conclusions: Lung deposition achieved using the spacer with facemask was higher than previously reported, with a difference of only 4.4% of total dose measured compared to the deposition with mouthpiece. This may be due to a combination of factors including pMDI formulation, and use of an antistatic spacer with a flexible, well-fitting facemask.