Combined anesthesia refers to any combination f regional and general anesthesia, usually a combination of epidural and general anesthesia. Combined anesthesia has been associated with less sedation, earlier ambulation, higher pulmonary flow
rates,
improved oxygenation, blunting of the stress response and better pain control in the postoperative period. Currently the most commonly employed method of anesthesia for open heart surgery patients is general anesthesia supplemented with opioids
and
postoperative pain control with IM morphine.
Theis study was undertaken to compare the total doses of fentanyl and vecuronium, duration of endotracheal intubation and ventilatory support, cardiovascular changes, changes in arterial bllod gas, changes in cortisol and -endorphin, and the
postoperative pain scor in 40 open heart surgery patients given a routine anesthetic regimen or combined anesthesia. Group A(n=20) was given general anesthesia, maintained with a nitrous oxide (2L/min)-oxygen (2L/min)-isoflurane(0.5-2.0 Vol. %)
gas
mixture and fentanyl (initial dose 10 g/kg with additional doses as required) with routine postoperative care with IM morphine sulfate and Group B (n=20) was given light general anesthesia nitrous oxide (2L/min)-oxygen (2L/min)-isofurane (0.2-0.5
vol.
%) and a continuous epidural infusion of a combination of 0.125% bupivacaine and fentanyl (10 g/ml) through an infusion pump from the start of the operation until the third postoperative day.
@ES The results were as follows;
@EN 1. The total amount of fentanyl given to Group B was significantly lower than the amount given to Group A.
2. The duration of endotracheal intubation and ventilatory support was significantly shorter in Group B compared to Group A.
3. The heart rate was slightly higher in Group B compared to Group A, but the only significant difference was seen 30 minutes after skin incision. There was no significant difference in the systolic pressures between the two groups but comparison
of the
diastolic pressures before cardiopulmonary bypass (CPB) and before skin closure showed significantly higher pressures for Group B. The pulmonary artery pressure (PAP) remeined stable in Group A while in Group B, the PAP gradually increased to
show
a
significant increase on POD2. The pulmonary capillary wedge pressure (PCWP) was significantly higher in Group B compared to Group A on POD2. The cardiac output (CO) and cardiac index(CI) was stable in Group B while for Group A, there was a
significant
decrease from during operation ot POD2. The systemic vascular resistance(SVR) showed a significatn increase in Group Afrom during operation to POD1 and POD2 and a significant difference between Group A and Group B on POD1 and on POD2. The
pulmonary
vascular resistance(PVR) increased significantly from during the operation to POD2 in both Groups A and B. The stroke volume (SV) and stroke volume index (SVI) were significantly greater in Group B compared to Group A on POD2.
4. Analysis fo arterial blood showed no significant difference in pH and PCO2 while the PO2 of samples taken before CPB were significantly higher in Group B compared to Group A. The bicarbonate of samples taken skin closure was significantly
lower
in
Group B compared to Group A.
5. Changes in serum cortisol levels showed significantly lower values before skin closure, POD2, POD3 for Group B compared to Group A. The serum -endorphin levels were consistently lower in Group B than in Group A althouugh not statistically
significant.
6. Postoperative pain relief was evaluated as good, fair, and poor the scores for Group A were 20%, 60%, and 20% and for Group B 75%, 15%, and 10%, showing a higher percentage of good pain relief for Group B.
In conclusion, the beneficial effects of combined anesthesia are a reduction in the total dse of all anesthetic agents given, a reduction in duration of endotracheal intubation and postoperative ventilatory care, minimal cardiovascular changes,
attenuation of the tress response, and a better quality of postoperative pain control showing that combined anesthesia is an attractive alternative to general anesthesia for open heart surgery patients.
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