Low Tidal Volume Ventilation With Hyperoxia Avoidance During Cardiopulmonary Bypass (The FOCUS Trial)

The investigators will evaluate the effect of low tidal volume with varying FiO2 fractions during cardiopulmonary bypass on postoperative mortality and pulmonary complications. This will be a prospective, pragmatic, cluster randomized trial including all eligible adult cardiac surgical patients requiring cardiopulmonary bypass. Each week, all operating rooms will be randomized to one of three possible ventilation strategies during the period of cardiopulmonary bypass: 1) continuous low tidal volume ventilation with inspired oxygen fraction at 1.0, 2) continuous low tidal volume ventilation with inspired oxygen fraction at 0.21, and 3) no ventilation (apnea). The investigators will anticipate increase in plasma sRAGE and 8-iso-prostaglandin F2a levels in all three groups of patients during CPB with the highest levels immediately after cross-clamp release. The investigators will anticipate significant difference with at least 25% lower sRAGE levels in this group. The sub-study will also provide preliminary data on the behavior of the 8-iso-prostaglandin F2a which will be useful in further investigation of other targeted interventions to reduce ischemia-reperfusion injury to the lung during routine cardiac surgical operations.

Inclusion criteria

• >18 years of age
• Male and female patients undergoing elective cardiac surgeries requiring cardiopulmonary bypass.

Exclusion criteria

Emergency surgeries, surgeries requiring lung isolation and one-lung ventilation (OLV), heart or lung transplants, and mechanical circulatory support device implantation pulmonary thrombendarterectomies.

• Surgeries requiring one-lung ventilation will be excluded because of the inability to employ study intervention and the differential treatment of the lungs likely confounding any potential effect from the planned intervention.
• Lung transplant surgeries will be excluded for similar reasons as well as other confounding effects affecting the primary composite outcome.
• Heart transplants and mechanical circulatory support device implantation surgeries will be excluded because these patients already receive intervention as part of the institutional protocol at the primary study site.