Please see Bibliography of References for a list of abstracts, manuscripts and posters.
Giquel J, Rodriguez YF, Candiotti K, Barron M, Gologorsky E. IARS 2010 Annual Meeting; March 20-23, 2010; Honolulu, HI
Introduction: Near-infrared spectroscopy (NIRS) based technology has been increasingly used to monitor the perfusion of various vascular beds, guide hemodynamic support and transfusion therapy in critically ill patients. Conflicting claims have been made regarding the relative utility of these devices. The goal of this case report is to present the relative sensitivity and reliability of 2 different perfusion monitors utilized at 2 different locations, cerebral oximetry (INVOS) and StO2 (tissue oximetry, Hutchinson Labs) in a hemodynamically unstable patient undergoing an open heart procedure.
Case Report: A 50 year-old patient presented for coronary reconstruction due to severe coronary artery disease, ischemic cardiomyopathy with an ejection fraction of 45%. The procedure was initially planned to be performed off bypass. During the attempt to anastomose the left internal mammary artery to the left anterior descending artery the patient developed severe ST elevations, accompanied by hemodynamic instability. The decision was made to emergently go on cardiopulmonary bypass (CPB). After the completion of the revascularization an attempt was made to separate from CPB. The patient required massive inotropic support to maintain hemodynamic stability. Severe ST elevation persisted, along with severe anterior wall and apical hypokinesis. Despite intraaortic balloon counterpulsation (IABP) 1:1 and maximal inotropic support, the patient continued to deteriorate, and developed severe biventricular failure. Extracorporeal membrane oxygenation (ECMO) was initiated at 4 l/min with restoration of the blood pressure (BP). The patient was brought to ICU. ECMO was weaned off after 72 hours. Severe left ventricular apical and anterior wall hypokinesis persisted. During the intraoperative course StO2 and INVOS values were continuously recorded, collected and charted.
Discussion: During the prebypass period, when the patient was hemodynamically stable, StO2 and INVOS values were stable, close to baseline. During the first episode of hypotension (MAP 50 mmHg), approximately 30 min after the termination of bypass and preceding the initiation of IABP, INVOS values were noted to not change significantly, however, StO2 dropped by 30%. The second hypotensive episode took place at the peak of severe biventricular failure, when, despite maximal inotropic support, the BP decreased, MAP 40 mmHg. That incident was noted on both monitors as a decrease of greater than 35%. That episode precipitated placement of ECMO support. Despite the inotropic, transfusion and ECMO support, the MAP remained close to 45 mmHg for the next 45 min. During that time INVOS values were close to baseline, however, the StO2 values exhibited a variable pattern with multiple decreases to values indicating hypoperfusion. Once the hemodynamic stability was achieved, both INVOS and StO2 continued to be stable.
We concluded that cerebral autoregulation and mild hypercapnia were possible etiologies of the decreased INVOS sensitivity as compared to StO2 during extremely instability.