title: Tracheal tube resistance and airway and alveolar pressures during mechanical ventilation in the neonate.
abstract: The relationship between peak airway pressure, alveolar pressure and respiratory frequency was calculated for the range of compliances and airway resistances which might be encountered during mechanical ventilation of a 3-kg neonate. The pressure/flow relationships of 2.5, 3.0, 3.5 and 4-mm tracheal tubes were determined at a series of flows from 0.5 to 4 litres/minute. Peak airway and alveolar pressures were then measured at various frequencies and inspiratory:expiratory ratios with the tubes incorporated in a model lung. Large differences between peak airway and alveolar pressures developed when frequency was increased or inspiratory time decreased; the differences were greatest with the smaller tubes. Shortening expiratory time by increasing the frequency or altering the inspiratory:expiratory ratio resulted in increased end-expiratory pressure because of incomplete emptying of the lung.
authors.affiliation: Nuffield Department of Anaesthetics, Radcliffe Infirmary, Oxford, UK.
authors.forename: T R
authors.initials: TR
authors.lastname: Tipping
authors.forename: M K
authors.initials: MK
authors.lastname: Sykes
mesh_terms: D000403:Airway Resistance / Q000502:physiology*; D000769:Anesthesia, Inhalation / Q000295:instrumentation; D006801:Humans; D007231:Infant, Newborn; D007442:Intubation, Intratracheal / Q000295:instrumentation*; D011312:Pressure; D011650:Pulmonary Alveoli / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology; D012121:Respiration, Artificial; D012126:Respiratory Dead Space / Q000502:physiology; D015656:Respiratory Mechanics / Q000502:physiology*; D013990:Tidal Volume / Q000502:physiology