Surgical exposure and Hemodynamics
Hemodynamic monitoring is critical in patient care during cardiac surgery. The participation of the anesthesiologist is indispensable in patient care during this procedure. The ever-increasing advances in surgical techniques and the multidisciplinary teams’ experience have extended the use of off-pump CABG, to include patients with an increasing prevalence of comorbidities.
Off-pump CABG, presents a unique set of technical challenges for the anesthesiologist and surgeon; perhaps the most critical being to monitor and maintain stable hemodynamics and rhythm in an environment during surgical manipulations that occur in a “beating heart”.
In order to attain an adequate heart for exposure of the coronary arteries, a tissue stabilizing device (Octopus Medtronic) and a cardiac positioner (Medtronic Starfish) are placed, their function being, to lift the heart and expose the posterior vessels (Figure 1 ), this facilitates the making of anastomosis. The order of distal versus proximal anastomosis can often vary or be changed to adjust to various coronary anatomies and tolerances to grafting (10 ).
Appropriate preparation, guided therapy, and technical maneuvers can lessen such adverse hemodynamic changes. The total exposure of the heart for multiple coronary revascularizations (2-3 vessels), including the circumflex artery (AC) and posterior descending artery (ADP), is only possible with the use of stabilization devices that restrict the regional wall’s movement, either via suction or mechanical compression. These manipulations in a “beating heart” depress cardiac contractility and cause some hemodynamic impact (11 ).
In this clinical environment, CO monitoring becomes a useful tool for optimal anesthetic care. Fluid therapy remains a challenge in critical patient settings. Fluid overload will cause organic edema, consequently increasing mortality, while an inadequate circulation volume will result in coronary perfusion pressure and insufficient and inadequate oxygen supply.
Therefore, fluid status control (volume) is essential in critically ill patients. During the past decades, there have been significant developments in hemodynamic monitoring techniques, such as FloTrac / Vigileo  and PiCCO system (Pulse-Induced Contour Cardiac Output ), which incorporates a transpulmonary thermodilution technique (TPTD) (12 )(13 ).
The objective of this essay is to compare the administration of ESM and DEX infusion, in the hemodynamic response of patients undergoing off-pump CABG.