- Poster presentation
- Open Access
Cardiogenic oscillations reflect nonlinear lung mechanics
© BioMed Central Ltd 2008
- Published: 13 March 2008
- Inspiratory Flow
- Lung Mechanic
- Peep Level
- High Peep
- Intermediate Pressure
Heartbeats transfer mechanical energy to the lung, inducing variations in local compliance (dV/dP) , which translate to cardiogenic oscillations (COS) in the pressure-volume (PV) loop. We hypothesized that the COS-related local dV/dP change reflects intratidal nonlinear lung mechanics modulated by positive end-expiratory pressure (PEEP).
Ten piglets with atelectasis were investigated during constant inspiratory flow mechanical ventilation with PEEP of 0, 5, 8, 12 and 16 mbar, respectively. The airflow rate, airway pressure and ECG were recorded (sample frequency: 100 Hz). The inspiratory limb of the PV loop was partitioned into segments confined by two consecutive ECG R-peaks and containing one COS. Local compliances were analyzed as the local slope (dV/dp) within consecutive volume windows of 50 ml size.
COS-related local compliances reflect nonlinear lung mechanics. The information obtained by COS corresponds to what can be learnt from the sigmoid PV loop of a quasistatic manoeuvre with low compliance at low pressure, high compliance at intermediate pressure and again low compliance with overdistension. The intratidal pattern of COS-related compliances possibly reflects the nonlinearity of pulmonary volume distensibility, which, among others, is modulated by PEEP. Analysis of COS-related local compliances may open a window towards lung mechanics determination in spontaneous breathing.
This article is published under license to BioMed Central Ltd.