Review

Clinical review: Respiratory mechanics in spontaneous and assisted ventilation

Daniel C Grinnan^1* and Jonathon D Truwit²

• * Corresponding author: Daniel C Grinnan dg6j@virginia.edu

Author Affiliations

¹ Fellow, Department of Pulmonary and Critical Care, University of Virginia Health System, Virginia, USA

² E Cato Drash Professor of Medicine, Senior Associate Dean for Clinical Affairs, Chief, Department of Pulmonary and Critical Care, University of Virginia Health System, Virginia, USA

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Critical Care 2005, 9:472-484 doi:10.1186/cc3516

Published: 18 April 2005

Abstract

Pulmonary disease changes the physiology of the lungs, which manifests as changes in respiratory mechanics. Therefore, measurement of respiratory mechanics allows a clinician to monitor closely the course of pulmonary disease. Here we review the principles of respiratory mechanics and their clinical applications. These principles include compliance, elastance, resistance, impedance, flow, and work of breathing. We discuss these principles in normal conditions and in disease states. As the severity of pulmonary disease increases, mechanical ventilation can become necessary. We discuss the use of pressure–volume curves in assisting with poorly compliant lungs while on mechanical ventilation. In addition, we discuss physiologic parameters that assist with ventilator weaning as the disease process abates.