Mechanics of respiratory system in healthy anesthetized humans with emphasis on viscoelastic properties

Research output: Contribution to journalArticle

Abstract

The classic model of the respiratory system (RS) is comprised of a Newtonian resistor in series with a capacitor and a viscoelastic unit including a resistor and a capacitor. The flow interruption technique has often been used to study the viscoelastic behavior under constant inspiratory flow rate. To study the viscoelastic behavior of the RS during complete respiratory cycles and to quantify viscoelastic resistance (Rve) and compliance (Cve) under unrestrained conditions, we developed an iterative technique based on a differential equation. We, as others, assumed Rve and Cve to be constant, which concords with volume and flow dependency of model behavior. During inspiration Newtonian resistance (R) was independent of flow and volume. During expiration R increased. Static elastic recoil showed no significant hysteresis. The viscoelastic behavior of the RS was in accordance with the model. The magnitude of Rve was 3.7 +/- 0.7 cmH2O.l-1 x s, i.e., two times R. Cve was 0.23 +/- 0.051 l/cmH2O, i.e., four times static compliance. The viscoelastic time constant, i.e., Cve.Rve, was 0.82 +/- 0.11s. The work dissipated against the viscoelastic system was 0.62 +/- 0.13 cmH2O x 1 for a breath of 0.56 liter, corresponding to 32% of the total energy loss within the RS. Viscoelastic recoil contributed as a driving force during the initial part of expiration.

Details

Authors
Organisations
External organisations
  • Lund University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physiology

Keywords

  • Adult, Air Pressure, Anesthesia, Elasticity, Female, Humans, Lung Compliance, Male, Mathematics, Middle Aged, Models, Biological, Respiratory Mechanics, Respiratory Physiological Phenomena, Tidal Volume, Ventilators, Mechanical, Viscosity, Work of Breathing, Journal Article, Research Support, Non-U.S. Gov't
Original languageEnglish
Pages (from-to)132-40
Number of pages9
JournalJournal of Applied Physiology
Volume75
Issue number1
Publication statusPublished - 1993 Jul
Publication categoryResearch
Peer-reviewedYes