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TEL AVIV, Israel -- Two non-related studies published recently in one of the leading cardiac surgery journals reveal that a new Thermo-wrap technology preserves normothermia better than routine thermal care in patients undergoing off-pump coronary artery bypass (OPCAB).
The first study, a prospective randomized trial recently published in the Journal of Thoracic and Cardiovascular Surgery, has evaluated the efficacy of three intraoperative warming systems on the maintenance of normothermia during OPCABG. The study, which included 90 patients undergoing OPCAB surgery, reports that overall blood loss and transfusion requirements were reduced, indicating improved quality of perioperative care. The Swiss report supports earlier findings on cost reduction and perioperative hypothermia prevention. (Sessler, D.I., Complications and treatment of mild hypothermia, Anesthesiology, V 95, No 2, Aug 2001).
Perioperative disturbances of homeostasis resulting in increased perioperative bleeding and transfusion requirements are common complications in patients undergoing cardiac operations. With the resurgence of the off-pump technique for coronary artery bypass grafting, reduced perioperative bleeding and reduced use of blood products can be demonstrated. However, according to clinical experience from the Institute of Anesthesiology and Intensive Care in Triemli City Hospital, Zurich, Switzerland, there are still a considerable number of patients needing transfusions. One important reason for this finding, according to Dr. Hofers research, may be the development of severe perioperative hypothermia during OPCABG, impairing coagulation pathways. Dr. Hofer concludes that normothermia during off-pump cardiac surgery can best be achieved by a circulating-water garment (Allon Thermoregulation System).
The second study published in the Journal of Thoracic and Cardiovascular Surgery, shows similar results. This randomized, prospective, open-labeled, multi-center investigation involved patients from the Department of Cardiothoracic Surgery and the Post-Anesthesia Care, Tel-Aviv Sourasky Medical Center, Tel Aviv, Israel (Chief investigator: Dr. N. Nesher and Prof. G. Urezky); the Cleveland Clinic Foundation, Cleveland, Ohio (Dr. S. Insler); and the Centre Cardiologie du Nord, Paris, France (Dr. P. Nataf).
It is currently held that mild-to-moderate hypothermia during cardiac surgery plays a protective role in preventing myocardial damage by reducing oxygen consumption, mainly in the heart. Data from Dr. Neshers study appears to contradict this conviction and suggests that the protective role of hypothermia may not bestow any benefit on patients undergoing OPCAB.
According to the author, there is no need to reduce a patients core temperature during OPCAB surgery, even to mild hypothermia, as was once considered desirable during these kinds of procedures. The study group treated with the Allon Thermoregulation System (MTRE Advanced Technologies Ltd, Or-Akiva, Israel) was associated with reduced levels of IL-6 and Troponin I and with improved hemodynamics, findings which suggest that normothermia is closely related to reduce inflammatory responses to stress and subsequently to a lower rate of myocardial damage.
In agreement with the first study, the authors of this multi-center study conclude that in contrast to routine thermal care, the Allon Thermoregulation System maintains core normothermia in more than 80 percent of patients undergoing off-pump coronary artery bypass surgery. Normothermia is associated with better cardiac and vascular conditions, a lower rate of cardiac injury, and a lower inflammatory response.