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Letter by Lema Regarding Article, "High-Target Versus Low-Target Blood Pressure Management During Cardiopulmonary Bypass to Prevent Cerebral Injury in Cardiac Surgery Patients: A Randomized Controlled Trial".

Circulation. 2018;138:2442. DOI: 10.1161/CIRCULATIONAHA.118.034316 2442 Guillermo Lema, MD To the Editor: The article by Vedel et al1 tries to obtain information on the best perfusion pressure to be maintained during cardiopulmonary bypass (CPB) in a specific population of adult patients. The authors should be congratulated for this in-depth work. What is the correct perfusion pressure to be maintained during CPB? It is still unknown. A few groups have studied this clinical aspect of CPB during the past 30 years.2 As of now, we do not have an answer. Some groups prefer to keep a fixed cardiac index while a patient is on CPB; others prefer a specific pressure. Because the exact pressure is unknown, we adjust our decision according to clinicians’ preferences, which are based on experience, rather than hard data. Unfortunately, this article does not address the issue of perfusion pressure in older patients or neonates. In the past 15 to 20 years, we have had an increasing number of patients >80 years old. We are also dealing with neonates and surgeries within the first 2 weeks of life. In both groups of patients, there is uncertainty about the proper CPB pressure to be maintained. Moreover, it is not only complicated but also unethical to randomized those patients to different perfusion pressures. We may have to look for something new, maybe a metabolic marker that could give us the answer we have been looking for since CPB was instituted as a technique to be used in cardiac patients. In the meantime, we have to rely on experience, common sense, and personal preferences.