Premium
Flow‐dependent resistance of nasal masks used for non‐invasive positive pressure ventilation
Author(s) -
WINDISCH Wolfram,
BUCHHOLT Alexander,
STAHL Claudius A.,
SORICHTER Stephan,
GUTTMANN Josef
Publication year - 2006
Publication title -
respirology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 85
eISSN - 1440-1843
pISSN - 1323-7799
DOI - 10.1111/j.1440-1843.2006.00875.x
Subject(s) - pressure drop , flow resistance , endotracheal tube , medicine , flow (mathematics) , ventilation (architecture) , mechanics , tube (container) , expiration , volumetric flow rate , biomedical engineering , anesthesia , materials science , respiratory system , composite material , anatomy , intubation , thermodynamics , physics
Objective and background: Endotracheal tube resistance is known to be flow‐dependent and this understanding has improved the application of invasive ventilation. However, similar physiological studies on the interface between patients and non‐invasive positive pressure ventilation (NPPV) have not been performed. Therefore, this study was aimed at investigating the resistance of nasal masks used for NPPV. Methodology: The flow‐dependent pressure drop of the small (S), medium‐small (MS) and medium (M) Contour Nasal Mask (Respironics Inc., Murrysville, PA, USA) was measured with and without a connecting tube (length 18 cm, internal diameter 1.5 cm) in a laboratory study. The resistance was calculated by Rohrer’s equation using the standard least‐squares‐fit technique. The present study explicitly differentiated between the resistance of the nasal mask alone when measured against atmosphere and the additional resistance caused by the nasal mask when airtightly fitted to a model head (interaction with the face). Results: Higher flow rates resulted in a non‐linearly increasing pressure drop across the interface. This flow‐dependent resistance of the S/MS/M mask was comparably low when not interacting with the face, but increased when interacting with the face. This flow‐dependent resistance of the mask was several‐fold higher when adding the connection tube and tended to be higher during expiration. Conclusion: There is a non‐linear flow‐dependent pressure drop across the nasal mask which is low and independent of its size, but increases when interacting with the face. The connecting tube is the major determinant of the resistance originating from facial appliances used for NPPV.