The effect of the recruitment maneuver (as a new technique of open lung concept ventilation)‎ on the right side of the heart using transesophageal echocardiography study

الملخص EN

Background Open lung concept ventilation (OLCV) is a method of ventilation intended to maintain endexpiratory lung volume by increased airway pressure.

As this could increase right ventricular (RV) afterload, we investigated the effect of this method on RV outflow impedance during inspiration and expiration using transesophageal echo-Doppler in a trial to differentiate the RV consequence of increasing lung volume from those secondary to increasing airway pressure during mechanical ventilation.

Patients and methods Forty stable patients on mechanical ventilation because of different causes (bronchopneumonia, cerebral infarction, hypertensive intracranial hemorrhage, noncardiogenic pulmonary edema postoperative, and post-traumatic mechanically ventilated patients) were enrolled prospectively in a cross-sectional clinical study.

Each patient was first subjected to conventional ventilation (CV) with volume-controlled ventilation, followed by OLCV by switching to pressure-controlled mode, and then the recruitment maneuver was applied until PaO2/FiO2 was greater than 375 torr.

Hemodynamic (mean arterial pressure, central venous pressure, and heart rate) and respiratory (total and intrinsic positive end-expiratory pressure, peak, plateau, mean airway pressure, and total and dynamic lung compliance) measurements were performed before, 20 min after a steady state of CV, and 20 min after a steady state of OLCV.

Also, transesophageal echo-Doppler was performed at the end of inspiration and at the end of expiration to calculate the mean acceleration (ACmean), as a marker of the RV outflow impedance, 20 min after a steady state of CV and 20 min after a steady state of OLCV.

Results During inspiration, ACmean was significantly lower during CV compared with OLCV (P < 0.001).

Inspiration did not cause a significant decrease in ACmean compared with expiration during OLCV, but did do so during CV (P < 0.001).

In comparison with baseline and CV, OLCV was associated with a statistically significant higher central venous pressure (P < 0.001 for both), higher total quasistatic lung compliance (P < 0.001 for both), and dynamic lung compliance (P = 0.001 for both).

Moreover, the PaO2/FiO2 ratio of OLCV was significantly higher than that at baseline and CV (P < 0.001 for both).

Conclusion OLCV provides a more stable hemodynamic condition and better oxygenation and lung dynamics.

Moreover, OLCV does not alter RV afterload during inspiration and expiration as RV afterload appears to be primarily mediated through the tidal volume.