Left ventricular diastolic function during short-term positive end-expiratory pressure ventilation in dogs

Area of Science:

• Cardiovascular Physiology
• Respiratory Mechanics

Background:

• Positive end-expiratory pressure (PEEP) is used in mechanical ventilation.
• Its effects on left ventricular (LV) function, particularly diastolic properties, require further elucidation.

Purpose of the Study:

• To investigate the impact of PEEP on LV pressure, volume, and diastolic function in an acute animal model.
• To determine the relationship between PEEP, LV preload, and diastolic compliance.

Main Methods:

• Simultaneous measurement of LV pressure and volume (sonomicrometry) in anesthetized dogs.
• Continuous pericardial pressure monitoring to calculate transmural LV pressure.
• Application of varying levels of PEEP (0, 10, and 20 cmH2O).

Main Results:

• PEEP significantly reduced LV end-diastolic volume, transmural pressure, and stroke volume.
• LV peak diastolic filling rate (dV/dtmax) decreased with PEEP, independent of volume changes.
• LV diastolic compliance significantly decreased with increasing PEEP levels.
• Reduced diastolic filling rate correlated with reduced LV diastolic compliance.

Conclusions:

• PEEP ventilation impairs LV diastolic filling and compliance.
• The findings suggest a tamponade-like effect contributes to reduced LV preload during PEEP.
• These alterations in diastolic function are critical considerations in mechanical ventilation management.