Impact of Reverse Triggering Dyssynchrony during Lung-Protective Ventilation on Diaphragm Function: An Experimental...

Area of Science:

• Mechanical Ventilation
• Respiratory Physiology
• Diaphragm Function

Background:

• Reverse triggering dyssynchrony (RT) is a patient-ventilator interaction where respiratory muscles contract during passive mechanical insufflation.
• The impact of RT on diaphragm structure and function remains largely unknown.
• Establishing a reproducible animal model is crucial for investigating RT's effects.

Purpose of the Study:

• To create an animal model of RT in pigs with lung injury under lung-protective ventilation.
• To evaluate the impact of RT on diaphragm structure and function.
• To analyze the relationship between breathing effort during RT and diaphragm outcomes.

Main Methods:

• Lung injury was induced in 32 pigs via surfactant depletion and high-stress ventilation.
• Animals received either passive ventilation or lung-protective ventilation adjusted to promote RT for 3 hours.
• Diaphragm function was assessed via transdiaphragmatic pressure during phrenic nerve stimulation; biopsies evaluated structure.

Main Results:

• The lung-protective ventilation group with RT had lower tidal volumes and higher respiratory rates compared to passive ventilation.
• An 83% incidence of 1:1 entrainment pattern was observed during RT.
• High breathing effort during RT correlated with reduced diaphragm force and increased abnormal muscle fibers, while low effort showed preserved force.

Conclusions:

• RT in a pig model with lung injury and lung-protective ventilation is reproducible.
• High breathing effort during RT is detrimental to diaphragm function and structure.
• Low breathing effort during RT may preserve diaphragm force, suggesting effort modulation is key.