Monitoring: Equipment and Computers
Background and Goal of Study: An off-pump modification of coronary artery bypass grafting (OPCAB) is intended to avoid complications related to cardiopulmonary bypass, but can be accompanied by severe changes in hemodynamics requiring advanced monitoring (1). The transpulmonary single thermodilution (STD) is a novel method for cardiovascular monitoring allowing the simultaneous evaluation of myocardial preload and contractility as well as quantification of lung edema (2). However, the role of STD in off-pump cardiac surgery is still unsettled. Thus, our aim was to evaluate the use of STD in OPCAB.
Materials and Methods: We studied 11 patients who underwent elective OPCAB during total intravenous anesthesia (propofol and fentanyl). Before surgery, a 5F thermodilution catheter (Pulsiocath PV2014L20) was inserted into the femoral artery. Heart rate (HR), cardiac index (CI), cardiac function index (CFI), stroke volume index (SVI), stroke volume variations (SVV), global ejection fraction (GEF), left ventricular contractility index (dPmax), systemic vascular resistance index (SVRI), and other hemodynamic parameters were assessed by STD and continuous pulse contour analysis (PiCCOplus, Pulsion Medical Systems, Germany). The measurements were performed after induction of anesthesia, during and at the end of surgery, and at 2, 4, and 6 hrs postoperatively. The data were analyzed using the test of contrasts.
Results and Discussions: After induction of anesthesia, HR, CI, CFI, SVI, GEF, and dPmax declined in concert with an increase in SVRI (p < .05). During revascularization, dPmax and SVRI decreased transiently by 25% (p < .05) that necessitated administration of ephedrine in 8 of the patients. After the OPCAB, HR, CI, CFI, and SVV increased significantly in parallel with fluid resuscitation and intravenous infusion of nitroglycerin. These changes, as well as a decrease in SVRI by 20% (p < .05), were also observed postoperatively.
Conclusion: During OPCAB, STD is a valuable tool for monitoring of the volume status, myocardial performance, and vascular tone that might help in providing an adequate goal-directed hemodynamic management.