Factors Responsible for the Effectiveness of the Lund De-airing Technique
Condition: Complication of Surgical Procedure
Study type: Interventional

Summary: 
      The Lund de-airing technique is employed for cardiac de-airing in open left heart surgery. It
      consists of two main elements namely, opening of both pleura after the patient is on CPB
      (cardiopulmonary bypass)and disconnection of the ventilator before opening the left heart to
      ensure bilateral pulmonary collapse and a staged filling of the heart at termination of the
      CPB. The aim of this study is to analyze in a randomized manner two groups of patients to
      establish if one or both components are of primary importance for the effectiveness of the
      de-airing technique.
    

Detailed description: 
      Patients planned for open left heart surgery, mainly aortic valve replacement, will be
      included in the study. Patients with aortic valve replacement and concomitant coronary artery
      bypass with vein grafts only can also be included.

      Exclusion criteria are; significant chronic obstructive pulmonary disease/emphysema,
      significant (>50%)carotid artery disease, need of concomitant internal mammary harvesting,
      prior cardiac or pulmonary surgery, pulmonary adhesions preventing pulmonary collapse,
      previous radiation to the chest and prior severe chest trauma. Intraoperative exclusion
      criteria are; failure to obtain adequate bilateral Trans-cranial Echo-Doppler signals from
      the medial cerebral arteries, finding of adherent pleurae and accidental opening of the
      pleurae.

      Twenty patients will be randomized to two groups:

      Group I: Intact pleura bilaterally, disconnection of the ventilator during cardiopulmonary
      bypass (CPB), followed by staged filling of the heart.

      Group II: Open pleura bilaterally, disconnection of the ventilator during cardiopulmonary
      bypass to ensure bilateral pulmonary collapse followed by conventional filling of the heart.

      Data will be compared to a third historical control group, consisting of ten patients with
      open pleurae with the ventilator disconnected followed by staged filling of the heart.

      Primary outcomes:

        -  Duration of the de-airing procedure from the release of the aortic cross clamp to
           finished de-airing.

        -  Air microemboli to the brain registered on-line as gaseous microembolic signals on
           Trans-cranial Echo-Doppler (TCD). The sum of signals from the right and left middle
           cerebral artery are registered during the following time periods; from the release of
           the aortic cross clamp to start of cardiac ejection, from cardiac ejection to finished
           de-airing, and during ten minutes after finished de-airing.

        -  Magnitude of residual air emboli in the heart after finished de-airing as monitored by
           Trans-esophageal Echocardiography (TEE) with a Three-chamber view. The severity of
           residual air is classified in four grades after the appearance of visible air on TEE in
           left atrium (LA), left ventricle (LV) and aortic root (AO)as follows; Grade 0: no
           residual air, grade I: gas emboli detected in one of three anatomic areas during one
           cardiac cycle, grade II: gas emboli detected simultaneously in two of three anatomic
           areas during one cardiac cycle; grade III: gas emboli detected in all three anatomic
           areas during one cardiac cycle.
    

Intervention name(s): Open pleurae & conventional filling of heart; Intact pleurae & staged filling of heart
Intervention type(s): Procedure; Procedure
Intervention description(s): After completion of the left heart surgery, the heart will be actively filled with blood from the cardiopulmonary bypass circuit and lungs fully ventilated with positive end-expiratory pressure to flush out all air trapped in the lung veins and left heart. When there is no more visible air seen on Trans-esophageal echocardiography, the patient is weaned from cardiopulmonary bypass.; After the end of the left heart surgery, the heart is gradually filled with blood from the cardiopulmonary bypass circuit. Cardiac contractions fill the lungs with blood til no more air is seen in left heart on Trans-esophageal Echocardiography. Thereafter the lungs are ventilated with 50% of the estimated lung minute volume and 5 cm positive end-expiratory pressure and cardiac filling and de-airing continued. If no air is seen in the left heart full ventilation is started and the patient is weaned from cardiopulmonary bypass.
Other intervention name(s): Cardiac de-airing; Cardiac venting; Cardiac de-airing; Cardiac venting
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Supportive Care
Keywords: Cardiac de-airing; Air emboli; Trans-cranial Echo-Doppler; Intraoperative Trans-esophageal Echocardiography