Myocardial systolic function increases during positive pressure lung inflation

Area of Science:

• Cardiology
• Pulmonary Physiology
• Critical Care Medicine

Background:

• Positive airway pressure ventilation can dynamically affect cardiovascular function.
• Understanding the immediate impact of lung inflation on myocardial contractility is crucial for clinical management.

Purpose of the Study:

• To quantify the changes in myocardial contractile function during the initiation of positive pressure lung inflation.
• To determine the onset and magnitude of these functional changes at clinically relevant pressures.

Main Methods:

• Eight anesthetized pigs (40 kg) underwent direct measurement of left ventricular pressures and volumes using conductance volumetry.
• A single lung inflation with a 15 cm H2O airway pressure plateau (PPLI-15) was applied.
• Systolic function variables were analyzed from beats during resting apnea (zero airway pressure) and maximal lung inflation.

Main Results:

• Systolic elastance increased by approximately 15% during PPLI-15 compared to zero airway pressure.
• Other systolic function variables confirmed an increase in left ventricular contractile function during lung inflation.
• These changes were observed rapidly upon initiation of lung inflation.

Conclusions:

• Initiation of positive pressure lung inflation causes a prompt and significant enhancement of myocardial contractile function.
• Clinical monitoring of myocardial function requires consistent airway pressure and lung inflation conditions.
• Further research should explore the mechanisms behind this acute augmentation of cardiac contractility.