What is the proper procedure for de-airing a lung transplant in a patient under general anesthesia and mechanical ventilation?

De-airing a Lung Transplant

De-airing a lung transplant is accomplished by filling the heart while closing the left atrium, gentle suction on the aortic root vent, and controlled lung inflation/deflation cycles under direct visualization, with routine use of CO2 insufflation to minimize residual intracardiac air. 1

Primary De-airing Technique

The fundamental approach involves several coordinated steps:

• Fill the heart while closing the left atrial incision to displace air through the aortic root vent 1
• Apply gentle suction to the aortic root vent (or central lumen of endoaortic balloon if used) to evacuate air from the left heart chambers 1
• Inflate and deflate the transplanted lung repeatedly under direct visualization to identify and evacuate air pockets, particularly important in the early postoperative period 1

CO2 Insufflation Strategy

• Routine use of CO2 insufflation into the surgical field minimizes residual intracardiac air since CO2 is more soluble in blood than room air and absorbs more rapidly 1
• This technique is standard in minimally invasive cardiac procedures and directly applicable to lung transplantation 1

Ventilation Management During De-airing

Use lung-protective ventilation with tidal volumes of 6-8 mL/kg predicted body weight (never >8 mL/kg) during the de-airing process 2, 3

Key ventilator settings include:

• Initial PEEP of 5 cmH₂O, adjustable to 5-8 cmH₂O based on compliance 2
• Avoid zero end-expiratory pressure (ZEEP) at all times as this promotes alveolar collapse 2, 4
• Maintain plateau pressure <30 cmH₂O to prevent barotrauma to the newly transplanted lung 2, 5
• Use FiO₂ of 0.4-0.5 (40-50%) initially to minimize oxidative injury to the graft 2

Double-Lumen Tube Advantage

A double-lumen endotracheal tube or bronchial blocker is preferable as it allows selective inflation and deflation of the right lung during de-airing and assessment for bleeding after cardiopulmonary bypass 1

• This is particularly important early in the surgical team's experience with lung transplantation 1
• Selective lung ventilation facilitates visualization of air evacuation and hemostasis 1

Monitoring During De-airing

Transesophageal echocardiography (TEE) should be used continuously to:

• Visualize residual air in cardiac chambers 1
• Assess ventricular function after air evacuation 6
• Confirm adequate de-airing before discontinuing cardiopulmonary bypass 1

Critical Pitfalls to Avoid

Do not use tidal volumes >8 mL/kg, as this is a critical error that increases morbidity and mortality in transplanted lungs 2

Additional errors to avoid:

• Never use FiO₂ 1.0 throughout the case - this worsens oxidative injury to the graft 2
• Avoid excessive tracheal suctioning that may disrupt clot formation if bleeding is present 2
• Do not omit PEEP during one-lung ventilation as this promotes atelectasis 2

Fluid Management Considerations

Restrict fluid administration to 2-6 mL/kg/h during de-airing and the perioperative period, as liberal fluid administration (>6 mL/kg/h) is a major risk factor for postoperative pulmonary complications and graft dysfunction 2

• Goal-directed therapy with esophageal Doppler monitoring should guide fluid titration 2
• Hypotension and pulmonary edema are common immediately after lung transplantation 6

Post-De-airing Ventilation Strategy

Once de-airing is complete and cardiopulmonary bypass discontinued:

• Continue lung-protective ventilation with low tidal volumes (4-8 mL/kg predicted body weight) 5, 3
• Maintain driving pressure (plateau pressure minus PEEP) as low as possible, as this is the best predictor of ventilator-induced lung injury 2
• Monitor compliance of the respiratory system continuously to adjust PEEP appropriately 2