Heart-Protective Mechanical Ventilation in Postoperative Coronary Artery Bypass Grafting Patients

Abstract

Introduction: The effect of mechanical ventilation (MV) on hemodynamic parameters of cardiosurgical patients with multiple respiratory and cardiovascular risk factors may be detrimental, demanding not only lung- but heart-protective settings. Objective: This prospective study compared the hemodynamic effect and gas exchanges between several ventilator setting combination of Volume tidal, respiratory rate and end-expiratory pressure in post cardiac surgery patients. Design: Sequential study with a controlled group. Setting: Single cardiosurgical ICU. Patients: 119 patients after on-pump CABG surgery without severe hemodynamic and gas exchange disorders. Interventions: During the 1st postoperative hour (conventional ventilation) the intervention group patients ventilated with Vt 10 ml×kg-1, RR 14 /min, 5 cmH2O. During the 2nd hour, RR to 8 /min (reduced RR In the 3rd hour, Vt decreased to 6 ml×kg-1, RR returned to14 /min and increased to 10 cmH2O (low VT-high PEEP ventilation). In 24 patients from the control group MV settings in the 3rd hour did not change, so they were equal those in 2nd hour. Measurements: Respiratory mechanics, hemodynamic and arterial blood gas data. Main Results: Patients within low VT-high PEEP ventilation period had shown significantly lower alveolar ventilation and thoraco-pulmonary compliance, than during reduced RR ventilation; mean airway pressure and Vds/Vt within low VT-high PEEP ventilation were the highest, however driving pressure was lower. Vt decrease and increase on the 3rd hour did not lead to oxygenation improvement, and was characterized by the worst CO2 elimination. Hemodynamically, the significant CVP and pulmonary artery wedge pressure increase and cardiac output decrease during low VT-high PEEP ventilation were revealed; in 23.2% patients catecholamine therapy was initiated. In contrast, control group patients demonstrated no significant respiratory and hemodynamic changes without low VT-high PEEP ventilation. Conclusions: In postoperative cardiosurgical patients, MV with Vt 6 ml×kg-1 and 10 cmH2O is characterized by significantly worse oxygenation and elimination of CO2, and a less favorable hemodynamic profile than ventilation with Vt 10 ml×kg-1 and 5 cmH2O. Funding: No funding. Declaration of Interest: No competing interest. Ethical Approval: In prospective study approved by the local Ethics Committee of Almazov National Medical Research Centre included 119 on-pump CABG patients’ data during 2016-2017 years.