Corrective effect of diaphragm pacing on the decrease in cardiac output induced by positive pressure mechanical...

Area of Science:

• Physiology
• Critical Care Medicine
• Biomedical Engineering

Background:

• Positive pressure ventilation (PPV) is essential for life support but can reduce cardiac output (CO).
• Diaphragmatic contractions naturally enhance venous return through pressure changes.
• The potential of diaphragm pacing as an alternative or adjunct to PPV requires investigation.

Purpose of the Study:

• To evaluate diaphragm pacing alone for ventilation and its effect on CO.
• To assess if diaphragm pacing can improve CO when combined with PPV.
• To compare the efficacy of diaphragm pacing-induced ventilation with PPV.

Main Methods:

• Anesthetized ewes underwent measurements of cardiac output (CO) using thermodilution.
• Implanted phrenic nerve stimulation (iPS) was used for diaphragm pacing.
• CO was recorded during end-expiratory apnea, PPV, PPV with iPS, and iPS alone.

Main Results:

• Diaphragm pacing alone (iPS) maintained CO comparable to baseline apnea.
• PPV significantly decreased CO by 15% compared to apnea.
• Combining PPV with iPS (PPV-iPS) prevented the decrease in CO seen with PPV alone.
• Ventilation achieved with iPS was comparable to PPV.

Conclusions:

• Diaphragm pacing is a viable method for ventilation that does not compromise cardiac output.
• Diaphragm pacing can counteract the negative hemodynamic effects of positive pressure ventilation.
• Implanted phrenic nerve stimulation presents a promising approach for mechanical ventilation strategies.