Anesthetic Advantages of OPCAB Over MIDCAB
- Intubation: No need to selectively intubate one lung and avoids the potential hypoxemia caused by collapsing a lung.
- Cardiopulmonary Resuscitation (CPR): If CPR is needed, open chest CPR is much more effective than closed chest compressions.
- Cannulation: Standard cannulation sites are readily accessible.
- Defibrillation: Standard size paddles fit through a sternotomy incision while that may not be the case for a MIDCAB incision.
- Graftable Areas: Access to all coronaries.
Preoperative Considerations for Beating Heart Surgery
There are several very important considerations when approaching a beating heart CAB case:
- 1. Patient History.
- The anesthesiologist should be very familiar with the coronary anatomy in general, and with the patient's specific lesions in particular. It is not enough to know that the patient has 3-vessel disease; you must also be aware of the severity of the lesions and their specific locations. One should also know the ejection fraction (EF), and if there is a global cardiomyopathy, history of valvular disease or recent myocardial infarction (MI).
- 2. Communication between the Surgeon and the Anesthesiologist.
- The anesthesiologist is integral to the success of beating heart CABG. In contrast to CABG procedures that use CPB, beating heart CABG requires the anesthesiologist to proactively maintain stable hemodynamics and rhythm in an environment that changes rapidly because of regional ischemia and cardiac manipulation. The anesthesiologist's active role during beating heart CABG requires a new level of communication with the surgeon. The surgeon must communicate with the anesthesiologist when the heart is being displaced, when a coronary artery is occluded, and when a shunt has been inserted or removed. Likewise, the anesthesiologist must keep the surgeon informed about the use of inotropes or vasopressors, ST segment or rhythm disturbances, and the patient's general condition. In no other cardiac procedure has it been more important for the anesthesiologist to continually observe and treat the hemodynamic and rhythm responses to cardiac manipulation and regional ischemia.
Monitoring
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Monitoring |
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| EKG - electrocardiogram; PA Catheter - pulmonary artery catheter; TEE - transesophageal echocardiography |
Standard ASA monitors and arterial lines are needed during the beating heart surgery. Central vascular access is also necessary for administration of vasoactive drugs and monitoring. The Emory team recommends using an introducer through which you can rapidly feed a pulmonary artery catheter if required.
For ischemic monitoring, the electrocardiogram (EKG) is critical but also has important limitations. There is debate over whether to use a pulmonary artery (PA) catheter, transesophageal echocardiography (TEE), both, or other modalities in these cases, and this issue will be discussed later in this document.
Anesthetic Technique
The anesthetic management presents a particular challenge because it requires the anesthesiologist to balance two opposing problems. Ideally the anesthetic technique is geared towards allowing early extubation of the patient by giving short-acting drugs, and avoiding high-dose opiates that would prolong emergence. At the same time, the operation can be characterized by periods of hemodynamic instability which are easier to manage if the anesthetic is based on high doses of opioids. In addition, it can be difficult to estimate the depth of anesthesia at times when low doses of inhaled anesthetic are being given because the hemodynamic parameters are markedly affected by the surgical manipulation. In this situation we have found that the information given by the Bi-spectral index is a useful guide to help ensure that appropriate amnesia is provided to the patient. In addition, we use continuous infusion of an opioid such as fentanyl to provide analgesia. This option is well tolerated, even by patients who are hemodynamically unstable.28
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