Mechanical behaviour of the canine respiratory system at very low lung volumes

G. Dechman, A. M. Lauzon, J. H.T. Bates

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17 Citas (Scopus)

Resumen

We studied the changes in dynamic elastance and resistance of the respiratory system in 6 supine, anaesthetized, paralysed, tracheostomised and open chested dogs. Tracheal pressure (Ptr), tracheal flow (V) and 3 alveolar pressures (Palv by alveolar capsule) were measured continously for 20 min at 5 levels of positive end expiratory pressure (PEEP) between 0.1 and 0.5 kPa. The lungs were inflated to total lung capacity (TLC) at the start of each recording period. Lung elastance (EL) and resistance (RL) were estimated by fitting the equation Ptr=RL V · + ELV + K to the measured data for each breath by multiple linear regression (V = volume, K = constant). Airway resistance (Raw) was obtained from the difference between Ptr and Palv. EL increased progressively in the 20 min following lung inflations. The increase in EL over this time was about 45% of its baseline value at a PEEP of 0.1 kPa compared to an increase of only about 10% at a PEEP of 0.5 kPa. In contrast, RL changed very little over the recording period at all levels of PEEP. At low levels of PEEP Palv often bore no resemblance to Ptr indicating that significant airway obstruction or closure had occurred. These results suggest that the increase in EL at low PEEP was primarily due to the accretion of airspace closure, and that nonlinear tissue mechanical properties were responsible for the lack of change in RL.

Idioma originalEnglish
Páginas (desde-hasta)119-129
Número de páginas11
PublicaciónRespiration Physiology
Volumen95
N.º2
DOI
EstadoPublished - feb. 1994
Publicado de forma externa

Nota bibliográfica

Funding Information:
Acknowledgements. This work was supported by the Medical Research Council of Canada (MRC), the J.T. Costello Memorial Research Fund and the Respiratory Health Network of Centers of Excellence. G. Dechman is supported by the Physiotherapy Society of the Canadian Lung Association and the MRC.A.-M. Lauzon is supported by the Research Institute of the Royal Victoria Hospital, Montreal. J.H.T. Bates is a Chercheur-Boursier of the Fonds de la Recherche en Sante du Quebec.

ASJC Scopus Subject Areas

  • Physiology
  • Pulmonary and Respiratory Medicine

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