Factors Responsible for the Effectiveness of the Lund De-airing Technique

Study Overview
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Brief Summary
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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
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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.

Official Title
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Factors Responsible for the Effectiveness of the Lund Technique for De-airing Following Open Left Heart Surgery.

Conditions
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Complication of Surgical Procedure

Intervention / Treatment
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* Procedure: Open pleurae & conventional filling of heart
* Procedure: Intact pleurae & staged filling of heart


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients planned for aortic valve replacement with or without coronary vein bypass grafts Exclusion Criteria: Significant chronic obstructive pulmonary disease and emphysema Previous history of thoracic or cardiac surgery Patients requiring internal mammary artery harvesting Unilateral or bilateral pulmonary adhesions to chest wall Previous radiation to the chest Intraoperative Exclusion Criteria: Inability to obtain adequate bilateral Trans-cranial Echo-doppler signals Adherent pleurae Accidental opening of the pleurae

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Open pleurae & conventional filling of heart<br>In this group both pleurae will be opened and the ventilator disconnected during cardiopulmonary bypass to ensure bilateral pulmonary collapse. However, after completion of the left heart procedure, the heart will be filled with blood actively from the heart-lung machine and manual de-airing performed in a conventional manner and de-airing monitored by intraoperative trans-esophageal echocardiography (TEE). After de-airing is complete and patient has been weaned off the cardiopulmonary bypass the residual air in the left heart will be quantitatively assessed by TEE and Trans-cranial Echo-Doppler (TCD) over a period of 10 minutes. | Procedure: Open pleurae & conventional filling of heart<br>* 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.<br>* Other names: Cardiac venting;|
| Experimental: Intact pleurae & staged filling of heart<br>In this group both pleurae will be left intact and the ventilator disconnected during cardiopulmonary bypass. After completion of the left heart procedure, the heart will be filled with blood actively from the heart-lung machine in a staged manner after adequate cardiac contraction has been established. De-airing will be obtained by active cardiac contraction and staged mechanical ventilation and de-airing monitored by intraoperative trans-esophageal echocardiography (TEE). After de-airing is deemed complete and patient has been weaned off the cardiopulmonary bypass (CPB) the residual air in the left heart will be quantitatively assessed by TEE and Trans-cranial Echo-Doppler (TCD) over a period of 10 minutes. | Procedure: Intact pleurae & staged filling of heart<br>* 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.<br>* Other names: Cardiac venting;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Quantitative Assessment of Air Embolism to the Brain After Completion of Open Left Heart Surgery | Cerebral air emboli will be assessed quantitatively by On-line counting of gaseous microembolic signals (MES) by Trans-cranial Echo-Doppler (TCD) monitoring of the right and left middle cerebral artery. The sum of the gaseous microembolic signals registered from the right and left middle cerebral artery will be reported. | Time from the release of the aortic crossclamp to cardiac ejection, an average of 10-15 minutes | 
| Quantitative Assessment of Air Embolism to the Brain After Completion of Open Left Heart Surgery | Cerebral air emboli will be assessed quantitatively by On-line counting of gaseous microembolic signals (MES) by Trans-cranial Echo-Doppler (TCD) monitoring of the right and left middle cerebral artery. The sum of the gaseous microembolic signals registered from the right and left middle cerebral artery will be reported. | Time from cardiac ejection to finished de-airing, an average of 5-10 minutes | 
| Quantitative Assessment of Air Embolism to the Brain After Completion of Open Left Heart Surgery | Cerebral air emboli will be assessed quantitatively by On-line counting of gaseous microembolic signals (MES) by Trans-cranial Echo-Doppler (TCD) monitoring of the right and left middle cerebral artery. The sum of the gaseous microembolic signals registered from the right and left middle cerebral artery will be reported. | Period of ten minutes after finished de-airing | 
| Participants With <=Grade I Air Emboli as Assessed by Trans-esophageal Echocardiography (TEE) After Finished De-airing. | The severity of residual air emboli in three anatomic areas; left atrium, left ventricle and aortic root, is assessed by Trans-esophageal Echocardiography (TEE) and classified in grade 0-3 as follows, Grade o: 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 simultaneously in all three anatomic areas during one cardiac cycle. | 0-3 minutes after finished de-airing | 
| Participants With <=Grade I Air Emboli as Assessed by Trans-esophageal Echocardiography (TEE) After Finished De-airing. | The severity of residual air emboli in three anatomic areas; left atrium, left ventricle and aortic root, is assessed by Trans-esophageal Echocardiography (TEE) and classified in grade 0-3 as follows, Grade o: 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 simultaneously in all three anatomic areas during one cardiac cycle. | 3-6 minutes after finished de-airing | 
| Participants With <=Grade I Air Emboli as Assessed by Trans-esophageal Echocardiography (TEE) After Finished De-airing. | The severity of residual air emboli in three anatomic areas; left atrium, left ventricle and aortic root, is assessed by Trans-esophageal Echocardiography (TEE) and classified in grade 0-3 as follows, Grade o: 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 simultaneously in all three anatomic areas during one cardiac cycle. | 6-10 minutes after finished de-airing | 
| Duration of the De-airing Procedure | The de-airing procedure is deemed completed when the Trans-esophageal Echocardiography (TEE) no longer visualizes air emboli in the heart Chambers. The duration is likely to vary between individuals and reflects the complexity of the de-airing procedure. | Time from release of aortic crossclamp to finished de-airing | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Cardiac de-airing, Air emboli, Trans-cranial Echo-Doppler, Intraoperative Trans-esophageal Echocardiography