title: Pressure, flow and resistance characteristics of the pediatric Storz-Hopkins bronchoscopes.
abstract: Poiseuille's law describes the relationship between pressure and the flow of a gas or liquid of known viscosity through a conduit of known length and radius. In clinical bronchoscopy, resistance varies directly with changes in viscosity of the inspired gas and the length of the bronchoscope. According to Poiseuille's law, resistance varies inversely to the fourth power of the radius of the bronchoscope. Flow-pressure curves were generated for commonly used pediatric Storz-Hopkins bronchoscopes with and without telescopes and the resistance of each system was calculated. Extremely high resistance is encountered with the 2.5 x 20 cm bronchoscope with telescope in place, a fact that most pediatric endoscopists are well aware of. However, comparable resistance is encountered when the 3.5 x 30 cm bronchoscope is used with the telescope in place, a fact not well appreciated by most clinicians.
authors.affiliation: Department of Otolaryngology, University of Western Ontario, London, Canada.
authors.forename: J D
authors.initials: JD
authors.lastname: Keohane
authors.forename: V
authors.initials: V
authors.lastname: Forte
authors.forename: B
authors.initials: B
authors.lastname: MacPherson
mesh_terms: D000403:Airway Resistance; D020680:Bronchoscopes; D002648:Child; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing; D011312:Pressure; D012123:Pulmonary Ventilation; D012212:Rheology; D013499:Surface Properties