Biologically variable or naturally noisy mechanical ventilation recruits atelectatic lung

Area of Science:

• Critical Care Medicine
• Respiratory Physiology
• Biomedical Engineering

Background:

• Biologically variable mechanical ventilation (Vbv) mimics spontaneous breathing variability.
• Vbv is hypothesized to improve gas exchange in lung injury by promoting alveolar recruitment.
• The variability in Vbv can be modeled as an inverse power law frequency distribution.

Purpose of the Study:

• To compare the efficacy of Vbv in reinflating a collapsed lung versus conventional ventilation (Vc) and ventilation with sigh breaths (Vs).
• To investigate the physiological effects of Vbv in a porcine model of atelectasis.

Main Methods:

• A porcine model of atelectasis was used, involving right lung collapse with one-lung ventilation.
• Seven pigs received Vbv, seven received Vc, and eight received Vs over a 5-hour period.
• Gas exchange, respiratory system compliance (Crs), and airway pressures were monitored.

Main Results:

• Vbv significantly enhanced collapsed lung re-inflation, leading to higher PaO2, lower PaCO2, and reduced shunt fraction compared to Vc and Vs.
• Vbv resulted in higher Crs and lower mean peak inspiratory airway pressures (Ppaw) than Vc and Vs.
• Tidal volume increased by 11% with Vbv compared to Vc, and the programmed respiratory rate variability followed an inverse power law distribution.

Conclusions:

• Biologically variable mechanical ventilation (Vbv) is superior to conventional ventilation in improving gas exchange and lung re-inflation in a model of atelectasis.
• The findings support the theoretical model of 'noisy' ventilation promoting better recruitment of collapsed lung tissue.
• Vbv demonstrates enhanced performance in mechanical ventilation, suggesting potential clinical benefits for patients with lung injury.