DISCUSSION
In our study, we found that DEX infusion has a predictable cardiovascular effect, which was observed during the impregnation of the infusion, a 20% drop in blood pressure is reported in the literature and a 10-20% drop in heart rate over baseline parameters is also expected. We also observed a reduction in narcotic consumption by the DEX group.
The results obtained with the use of DEX, hemodynamic stability during coronary anastomosis was beneficial, and also facilitated the technique on a beating heart in patients undergoing off-pump CABG (3 )(16 ).
The hemodynamic data was collected at four different times: baseline, at the time of sternotomy, coronary anastomosis, and placement of the sternal closure. These off-pump CABG surgical times were chosen because they are reasonably considered the most significant painful stimuli during sternotomy and the placement of sternal closure at the time of coronary grafting (17 )(18 )(25 ).
Tachycardia is poorly tolerated in patients with heart failure, as this may predispose the patient to cardiac arrhythmias during the transoperative period. Consequently, atrial fibrillation and subsequent myocardial ischemia may occur, thus leading to fatal complications in some cases (19 )(26 ).
The use of DEX, due to its pharmacological property, can be used to prevent tachycardia and attenuate the hemodynamic response during cardiac surgery.
Studies suggest that the perioperative use of DEX may result in a decreased risk of adverse cardiac events, including myocardial ischemia. Stimulation of α-adrenergic receptors can modulate coronary blood flow during myocardial ischemia, by preventing the redistribution of blood flow, which leads to improvement of coronary perfusion. (27-28 )
This specific effect, along with hemodynamic stability andreduced surgical stimulus-response, make DEX an ideal adjuvant anesthetic, particularly in patients undergoing coronary bypass grafting.
Hemodynamic monitoring should be applied within the context of therapeutic interventions, which have proven effective in the reversal of the disease process (20 )(21 ).
The risk of adverse events in off-pump CABG, increases in patients with specific comorbidities, such as recent myocardial infarction, left ventricular ejection fraction (LVEF <40%), a history of lung disease or renal dysfunction. The impact of comorbidities on postoperative morbidity and the outcome have also been studied in cardiac surgery where the use of hemodynamic therapy in the perioperative period has been associated with a decrease in the incidence of overall complications or length of postoperative stay in cardiac surgery. Several interventions in the ICU after cardiac surgery have been investigated, but the results have yet to significantly change clinical practice (22 ).
Currently, these critically ill patients are hemodynamically optimized with ”early goal-directed therapy” (EDGT), which in high-risk surgery has been associated with a reduction in postoperative morbidity and mortality along with a decrease in cardiac complications, particularly in the case of arrhythmias (12 )(29 ).
Clinical studies that have been performed individually for cardiac surgery, with a hemodynamic approach aimed at the goal of therapy during the perioperative period, the hemodynamic objectives have been to maintain: MAP 60–100 (mmHg); heart rate ≤90 (bpm); Hb ≥8 (g/dl); SVO2 ≥60(%), CVP 6-8 (mmHg), Stroke Volume Variation (SVV) 10 (%); stroke volume index (SVI) 30–65 ml; SVRI 1500–2500 (dyne x sec x cm-5 x m-2); Oxygen delivery (DO2) 450–600 (ml/ min/ m2); Hct ≥30(%); pH 7.35–7.45; PO2 100mm Hg; PCO2 35–45 mm Hg; SpO2 ≥95%, Lactate ≤2 (mmol/l) after 8 h from the postoperative period (23 )(24 ).