The effect of positive end expiratory pressure on right ventricular functions in coronary artery bypass graft surgery

Background: This study aims to investigate the effect of positive end-expiratory pressure on the right ventricular functions by speckle tracking method in patients undergoing coronary artery bypass grafting. Methods: This prospective study included a total of 20 patients (17 males, 3 females; mean age 59.7 +/- 10.5 years; range 42 to 77 years) who underwent coronary artery bypass grafting between May 2013 and September 2013. After initiation of 5 cmH(2)O positive end-expiratory pressure during mechanical ventilation before sternotomy, 10 and 20 cmH(2)O of positive end-expiratory pressure were applied in five-min intervals, respectively. Four-chamber and two-chamber views of the right ventricle were recorded at each pressure level using transesophageal echocardiography. The right ventricle diameter and velocity, longitudinal strain and strain rate, and right ventricle fractional area change were calculated. Results: Intraoperative systolic, diastolic, and mean blood pressures and mean heart rate were similar at the three positive end-expiratory pressure levels. The mean right ventricle strain value was significantly lower at 20 cmH(2)O pressure (p<0.001 for both). The mean strain rate was significantly lower at 20 cmH(2)O pressure, compared to 5 cmH(2)O pressure (p=0.03). The right ventricle velocity was found to significantly decreased with increasing positive end-expiratory pressure (p<0.05). The mean right ventricle fractional area change was similar at 5 and 10 cmH(2)O pressures (p=0.063), while it was significantly lower at 20 cmH(2)O pressure (p=0.001). The mean right ventricle diameter decreased with increasing positive end-expiratory pressure, while this decrease was significant at 20 cmH(2)O pressure (p=0.01). Conclusion: Our study results show that 5, 10, and 20 cmH(2)O positive end-expiratory pressures does not significantly change hemodynamic data in patients undergoing coronary artery bypass grafting with normal right ventricular functions; however, 20 cmH(2)O positive end-expiratory pressure leads to decreased right ventricular functions, as assessed by transesophageal echocardiography.