2012 OPEN FORUM Abstracts
LUNG DEPOSITION OF 99MTC-SALBUTAMOL FROM A PRESSURISED METERED DOSE INHALER AND VALVED HOLDING CHAMBER, USED WITH FACEMASK OR MOUTHPIECE IN CHILDREN WITH STABLE ASTHMA - A PILOT STUDY.
Sunalene Devadason1, William Ditcham1, Jasminka Murdzoska1, Christina Roller1, Dirk von Hollen2, Kurt Nikander2; 1School of Paediatrics and Child Health, University of Western Australia, Perth, WA, Australia; 2Philips Respironics, Respironics New Jersey, Inc., Parsippany, NJ
Pressurised metered dose inhalers (pMDIs) are an effective and convenient method of delivery of inhaled medication to patients with asthma. Valved holding chambers (VHCs) can improve the delivered dose to the lungs while minimising adverse effects from oropharyngeal deposition. The use of VHCs with facemasks is required in young children until they can use a mouthpiece. Early research showed that oral inhalation via a mouthpiece was more efficient than the combination of oral and nasal inhalation which occurs when using a facemask. Recent improvements in facemask design and materials have highlighted the need for new comparative studies between VHC facemasks and mouthpieces. Research Questions: 1. How does lung deposition from a pMDI-VHC with a newly designed, well-fitting facemask compare with a mouthpiece? 2. At what age can children be trained to use a mouthpiece effectively? Methods: Four children (3 male) with stable asthma aged 4-5 years were included. One child (male, 5 years) was screened but not included due to non-compliance with both facemask and mouthpiece use. A transmission scan of each patient was initially taken, using a flood source containing 37MBq 99mTc. In total 180 mg of 99mTc-labelled salbutamol (ProAir, TEVA) was administered to each patient through an antistatic VHC (OptiChamber Diamond, Philips Respironics) with either a dedicated facemask (LiteTouch, Philips Respironics) or a mouthpiece interface, on separate occasions in random order. Simultaneous anterior and posterior planar scintigraphic scans (120 sec acquisition time) were taken immediately after salbutamol inhalation. Students t-test for paired data was used to test for significant differences (p < 0.05) between the two study arms (facemask and mouthpiece). Results: Mean (SD) lung deposition (% label dose) was 17.0 (2.9)% for the facemask and 19.1 (10.2)% for the mouthpiece when corrected for tissue attenuation (p>0.05). Lung deposition in the peripheral compared with central regions (P:C ratio) was 1.5 (0.5) for the facemask and 1.1 (0.5) for the mouthpiece (p < 0.001). There was no difference (p>0.05) in oropharyngeal and gastrointestinal deposition with the two interfaces (21.7 (7.7) and 20.2 (1.4) for the facemask and mouthpiece respectively. Conclusions: Contrary to previous studies, there was no difference in lung deposition with the use of the facemask compared with a mouthpiece. Peripheral lung deposition was significantly higher with the use of the facemask. Sponsored Research - Partial sponsorship for this study was provided by Philips Respironics. The work was primarily supported by a research grant awarded by the Princess Margaret Hospital for Children Foundation, Perth, Western Australia