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.