|Year : 2016 | Volume
| Issue : 1 | Page : 30-35
Epidural dexmedetomidine and bupivacaine in off-pump coronary artery bypass graft: does it help in fast tracking?
Magdy M Atallah1, Sanad Mohamed2, Saada Islam2
1 Mansoura Anesthesia Department, Mansoura Faculty of Medicine, Mansoura, Egypt
2 Mansoura Cardiothoracic Surgery Department, Mansoura Faculty of Medicine, Mansoura, Egypt
|Date of Submission||19-Sep-2015|
|Date of Acceptance||23-Nov-2015|
|Date of Web Publication||15-Jun-2016|
Magdy M Atallah
Mansoura Anesthesia Department
Source of Support: None, Conflict of Interest: None
Background Fast-track cardiac surgery is an important global concern as it can decrease the duration of ICU stay, duration of hospitalization, and total cost of cardiac surgery. The greater the success in fast-track cardiac surgery, the greater the survival rate as there will be fewer cancellations due to unavailability of beds.
Objective Our aim is to assess the impact of thoracic epidural dexmedetomidine-bupivacaine on the hemodynamics and analgesic profile, and thus in fast-tracking surgery in patients subjected to off-pump coronary artery bypass grafts (CABG).
Patients and methods Fifty-six patients of either sex, aged 50–70 years, subjected to off-pump CABG were randomly assigned to two groups: a control group receiving general anesthesia (GA); and an epidural general group receiving GA combined with thoracic epidural dexmedetomidine 1 μg/kg with 8 ml 0.25% bupivacaine and top-up doses of 2 ml. Bupivacaine 0.25% was given hourly during the operation until closure of the sternum. Perioperative hemodynamics (heart rate, mean arterial pressure, and central venous pressure) and PaCO2, PaO2, and pH were recorded at the following intervals: at baseline, before skin incision, before sternotomy, after sternal closure, and in the ICU. Time to awakening and time to extubation were recorded. Also, analgesics and vasoactive and vasodilator medications were recorded. Pain assessment was made using the visual analogue scale on a scale of 0–10. Total duration of stay in ICU and hospital stay was recorded.
Results Postoperative heart rate and mean arterial pressure were significantly lower in the epidural group when compared with the control group. Time to first awakening and extubation was also significantly earlier in the epidural group than in the control group. Total intraoperative fentanyl dose (μg/kg) was less in the epidural group than in the general group, and postoperative morphine requirements (mg/kg) were significantly lower in the epidural group than in the control group. There was lesser need for cardiovasoactive drugs (β-blockers, inotropes) and vasodilators in the epidural group compared with the control group. Visual analogue scale revealed better analgesic profile at the time of extubation in the epidural group. Total ICU and hospital stay was significantly shorter in the epidural group than in the control group.
Conclusion GA supplemented with thoracic epidural dexmedetomidine with bupivacaine in off-pump CABG resulted in more perioperative hemodynamic stability, earlier extubation, lower pain score, and less analgesics, vasoactive and vasodilator drug requirements compared with GA alone. Successful fast tracking of cardiac surgery in off-pump CABG can be achieved using this anesthetic technique.
Keywords: cardiac surgery, epidural dexmedetomidine, fast track, off pump
|How to cite this article:|
Atallah MM, Mohamed S, Islam S. Epidural dexmedetomidine and bupivacaine in off-pump coronary artery bypass graft: does it help in fast tracking?. Res Opin Anesth Intensive Care 2016;3:30-5
|How to cite this URL:|
Atallah MM, Mohamed S, Islam S. Epidural dexmedetomidine and bupivacaine in off-pump coronary artery bypass graft: does it help in fast tracking?. Res Opin Anesth Intensive Care [serial online] 2016 [cited 2020 Jun 4];3:30-5. Available from: http://www.roaic.eg.net/text.asp?2016/3/1/30/184082
| Introduction|| |
Dorsal epidural anesthesia in cardiac surgery has reversible sympatholytic effects that decrease the response to surgical stress and improves both myocardial metabolism and perioperative analgesia ,. These effects have been proved to result in earlier extubation and a more pleasant postoperative course. Nasr and Abdellhamid in 2013  demonstrated a significant reduction in stress response validated by reduction of serum cortisol and blood glucose levels in children undergoing cardiac surgeries who received a single dose of dexmedetomidine (α2-agonist) and bupivacaine in the caudal epidural space. They also reported a concomitant decrease in heart rate (HR), mean arterial pressure (MAP), better postoperative pain control, and a shorter time to extubation in comparison with patients who received a bolus dose of caudal epidural fentanyl and bupivacaine .
Intravenous dexmedetomidine attenuated the hemodynamic and neuroendocrine response of surgical trauma and cardiopulmonary bypass machine . Previous studies reported that α2-agonist effects are more effective after neuroaxial approach than after intravenous route ,. Sharma in 2013 , revealed that a high thoracic epidural infusion of a combination of dexmedetomidine and local anesthetic was superior than the caudal approach in pediatric cardiac surgeries.
This study hypothesized that addition of dexmedetomidine to bupivacaine in the dorsal epidural space as neuroaxial analgesia in off-pump coronary artery bypass graft (CABG) surgery may improve outcomes, as seen in previous studies.
The aim of this study was to assess the impact of dorsal epidural dexmedetomidine with bupivacaine on perioperative hemodynamics in successfully fast-tracking surgery as compared with general anesthesia (GA) alone in patients subjected to off-pump CABG.
| Patients and Methods|| |
This prospective, randomized [computer-generated allocation table (graph pad software)], controlled study included 56 adult patients of either sex aged 50–70 years of ASA II and III physical status scheduled for elective off-pump coronary artery bypass surgery at the Cardiothoracic Surgery Department, in Mansoura University Hospital, and Mansoura International Hospital between January 2013 and April 2015. Approval of the Ethics Committee board of Mansoura Faculty of Medicine and written informed consent from all patients were taken.
Exclusion criteria were urgent surgery, active ischemia or unstable angina, acute myocardial infarction in the last 3 months, prior cardiac surgery, left ventricular ejection fraction less than 0.4, permanent pacemaker, preoperative need for inotropic agents, severe pulmonary hypertension (>100 mmHg), uncontrolled diabetes, serum creatinine higher than 1.5 mg/dl, impaired liver functions, chronic atrial fibrillation, and moderate to severe valvular disorders. Exclusion factors were coagulopathy, platelet count less than 100 000/ml, and patient refusal to participate.
The day before surgery all patients underwent a preoperative evaluation, which included a history of medical disorder, clinical examination, and evaluation of ECG, chest radiograph, cardiac catheterization report, recent echocardiography, and laboratory investigations (complete blood count, bleeding time, clotting time, prothrombin time, partial thromboplastin time, blood sugar, liver function tests, renal function tests, and urine analysis). Then the study protocol and visual analogue scale (VAS) were explained to every patient and consent was taken.
Oral alprazolam 1 mg (Xanax; Pfizer) was taken the night before surgery. Patients were premedicated with intravenous midazolam 0.02 mg/kg and morphine 0.05 mg/kg through an intravenous cannula and then oxygen supplementation was given through a face mask. Patients were randomly classified using the computer-generated allocation table into two groups (28 patients each): The GA/Epi (general/epidural) group and the GA (GA alone) group. In the GA/Epi group an epidural catheter was inserted 12 h before induction of GA, with the patient in the sitting position, using an 18-G needle, in the epidural space between the T4 and T6 spines using loss of resistance. If bloody tap occurred patients received GA and were excluded from the study and replaced by another patient. After a negative epidural test dose of 3 ml of 1.5% lidocaine with epinephrine, the epidural catheter was injected with 8 ml of bupivacaine 0.25% and dexmedetomidine (1 μg/kg) Precedex (2 ml at 100 μg/ml (Hospira Ball Inc., Spain) to be adjusted to 1 ml using distilled water, with top-up doses of 2 ml of bupivacaine 0.25% given hourly during the operation. The GA group received GA without epidural block.
Routine monitoring was established by inserting arterial and central venous lines under local anesthesia. The GA was the same in both groups, as induction was with intravenous fentanyl 4–5 μg/kg, propofol 1 mg/kg, and atracurium 0.5 mg/kg to facilitate endotracheal intubation. The patients were then mechanically ventilated to maintain end-tidal CO2 around 35 mmHg. Anesthesia was maintained with 0.2–1% of isoflurane in oxygen with an intravenous infusion of fentanyl 1–2 μg/kg/h, propofol 50 μg/kg/min, and top-up doses of atracurium to stabilize hemodynamic changes within 25% of the baseline. Propranolol increments (0.2 mg) were given when HR exceeded 80 beats/min, and atropine increments (0.2 mg) were given when HR decreased below 50 beats/min. Hypotension was treated with increased fluid flow ± noradrenaline, and hypertension was treated with increased back-up flow of fentanyl/propofol.
The surgical steps were standardized. A femoro-femoral bypass sheath was introduced for emergency shift to CPB. Median sternotomy was performed, and heparin 200 IU/kg was given intravenously to get activated clotting time of about 250–300 s. The left internal mammary artery was harvested in all patients. Activated clotting time was repeated every 30 min; heparin was received as needed. Intravenous infusion of 2 g of magnesium sulfate was infused on pericordial window. Traction sutures were applied on the pericardium and elevating pads were used to get good visibility and access to either the left or the right side of the myocardium. A mechanical suction stabilizer (Octopus Medtronic; Medtronic Inc., Minneapolis, Minnesota, USA) was used to facilitate the surgery.
All parameters were recorded by anesthetic care givers and nurses.
- Intraoperative parameters: HR, MAP, and central venous pressure (CVP) were recorded before induction of anesthesia (basal), after skin incision, 2 min after sternotomy, and after closure of the sternum. Anesthesia duration, number of grafts done, anastomosis time, and incidence of dysrhythmia were recorded. Total doses of fentanyl (μg/kg), atropine, b-blocker inotropes (epinephrine or dopamine), and/or vasodilator (nitroglycerine) at μg/kg/min were recorded.
- ICU parameters: Hemodynamics (HR, blood pressure, and CVP) and ABG were measured on arrival at the ICU and then every 1 h until tracheal extubation. Time to awakening, time to extubation, and serial arterial blood gases were recorded. Analgesia was achieved by top-up doses of intravenous morphine (3–5 mg) when VAS score was greater than 4. VAS was recorded at the time of extubation. The patient was discharged from the ICU when he or she had fulfilled the criteria of discharge (patient fully awake, stable hemodynamics without the need for inotropes, vasoactive drugs, SaO2>90% on FiO2<0.4, no dysrhythmia, urine output3 0.5 ml/kg/h). Total ICU and hospital stay was recorded. Epidural catheter was removed on the second day after surgery whenever there was no evidence of bleeding or coagulation problems. Any incidence of complications was recorded.
Sample size was calculated on the base of time of extubation after arrival at the ICU. The expected difference was around 25%. The independent t-test was used for comparison and a-value settled at 0.05. A sample size of 23 cases per group was required to get a power of more than 90%. The study finally included 28 patients per group to compensate for possible dropouts. Calculations were performed using G power 3.0.10 software. Statistical analysis was performed using SPSS, version 17 (SPSS Inc., Chicago, Illinois, USA). Normality of data was tested using the KolmogorovSmirnov test. Normally distributed data were tested by means of the Student t-test. Abnormally distributed continuous data were tested by means of the MannWhitney U-test. The c2-test or Fisher's exact test was used as appropriate for categorical data. Data were presented as mean ± SD or number (%). A P value less than 0.05 was considered statistically significant.
| Results|| |
Four patients were excluded from the study: two because of the incidence of bloody tap and two because of urgent need for cardiopulmonary bypass. These patients were replaced by others.
Patient demographics and preoperative data showed no significant differences as regards age, sex, BMI, history of hypertension, myocardial infarction, ejection fraction, and chronic obstructive pulmonary disease between the groups. Also, patients on b-blockers and antiplatelet therapy showed no statistically significant differences between the two studied groups ([Table 1]).
In this study, the HR (beats/min) showed significant decrease (P < 0.05) in the group that received GA supplemented with epidural (GA/Epi group) when compared with patients who received GA (GA group) after closure of sternotomy until 24 h postoperatively ([Table 2]).
MAP (mmHg) was significantly lower (P < 0.05) in the GA/Epi group compared with the GA group after anastomosis until 24 h postoperatively ([Table 3]).
|Table 3: Perioperative mean arterial pressure (mmHg) in the studied groups|
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As regards operative events, such as total anesthesia time (min), number of grafts anastomosed, anastomosis time (min), dysrhythmia (rhythm other than sinus rhythm), and CVP (cmH2O) after induction, there were no significant differences between the two studied groups. However, the total fentanyl dose (μg/kg) used intraoperatively was statistically significantly lower in the GA/Epi group as compared with the GA group (11.6 ± 2.1 vs. 7.4 ± 1.2). Also, b-blockers, inotropes, and dilators were significantly lower in the GA/Epi group as compared with the GA group. CVP (cmH2O) after anastomosis and after closure of the sternum was significantly lower in the GA/Epi group as compared with the GA group ([Table 4]). P value less than 0.05 was considered statistically significant.
[Table 5] shows the postoperative parameters with respect to awakening time, as presented by eye opening, head and limb movement on command (h) (5.5 ± 2.1 vs. 2.6 ± 1.1), extubation time (h) (8.1 ± 2.7 vs. 5.1 ± 1.7), VAS (0–10) before extubation (6.8 ± 2.3 vs. 4.9 ± 1.7), total dose of morphine (mg/kg) used in the ICU (0.9 ± 03 vs. 0.5 ± 0.1), total ICU stay (h) (34.3 ± 5.6 vs. 23.8 ± 6.6), and total hospital stay (day) (8.5 ± 1.5 vs. 6.8 ± 1.2). All values were statistically significantly lower in the GA/Epi group as compared with the GA group (P < 0.05) [Table 5]. Arterial blood gases represented by pH, PaO2, PaCO2, and HCO3 showed no significant differences between the two studied groups across the study period. There were no recorded complications.
|Table 5: ICU parameters [time of awakening and extubation (h)], total morphine dose (mg/kg) in the ICU, pain intensity (visual analogue scale) before extubation, ICU length of stay (h), duration of hospitalization (day) in the studied groups|
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| Discussion|| |
The off-pump coronary artery bypass has several advantages on patient outcome without the complications arising from the use of a CPB machine. However, it requires a high degree of well-balanced anesthesia and analgesia to avoid dysrhythmia, hypotension, and more cardiac ischemia.
The present study revealed that supplementation of GA (GA/Epi group) by thoracic epidural 8 ml of bupivacaine 0.25% and dexmedetomidine (1 μg/kg), with top-up doses of 2 ml bupivacaine 0.25% given hourly during off-pump CABG, results in better hemodynamic stability as represented by HR, MAP, CVP, and less need for BB, inotropes and vasodilators compared with GA alone (GA group). Also, the GA/Epi group showed superior analgesic profile in the form of reduced intraoperative and postoperative analgesic consumption. Cardiac surgery could be fast tracked faster in the GA/Epi group than in the general group, as represented by decreased ICU and hospital stay.
Other studies reported the myocardial protective effect of dexmedetomidine through activation of cardiac kinases with increased cell survival from ischemia  or modulation of sympathetic tone and preservation of oxygen demandsupply ratio with decreased perioperative myocardial ischemia .
Many studies have proved the same outcome of this study as regards the synergism of quality and duration of analgesia between the use of a neuroaxial local anesthetic such as bupivacaine as a sodium channel blocker, as used in this study, and dexmedetomidine. They attributed that to the central action of dexmedetomidine at the spinal level by binding to the presynaptic C-fibers and postsynaptic dorsal horn neurons. They related its analgesic properties to decreased release of C-fiber transmitters and hyperpolarization of postsynaptic dorsal horn neurons ,,,,,.
As regards the stability of hemodynamics in the GA/Epi group seen in this study, Menda et al. in 2010  reported that dexmedetomidine stabilizes the HR when used in the anesthetic regimen during CABG even in patients on b-blockers, which was supported by our results. Further, Ruesch and Levy in 2002  advised the systemic use of dexmedetomidine to treat persistent tachycardia during off-pump CABG that did not respond to esmolol. Previous investigators have also proved the analgesic efficacy and hemodynamic stability through the central effects of dexmedetomidine on the sympathetic system and decreased plasma norepinephrine levels .
Our results as regards successful fast tracking within the GA/Epi group as compared with the control group are supported by many reports, which attributed it to the effects of dexmedetomidine as an adjunct to GA as it decreased inhalational and opioid requirements and resulted in rapid and smooth recovery. These benefits were evident in this study through decreased need for intraoperative fentanyl, postoperative morphine, earlier recovery, extubation, and hence less time needed in the ICU and hospital ,,,.
| Conclusion|| |
GA supplemented with thoracic epidural dexmedetomidine with bupivacaine in off-pump CABG results in more perioperative hemodynamic stability, earlier extubation, lower pain score, and less analgesics and vasoactive and vasodilator drug requirements compared with GA alone.
GA supplemented with addition of thoracic epidural dexmedetomidine with bupivacaine resulted in greater success in fast-tracking cardiac surgery in off-pump CABG patients compared with GA alone.
There are certain limitations to this study: the study was not blinded; stressors were not measured, which could have yielded a better outcome; and a single surgical team implies fewer variables affecting the study outcome.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]