Discussions
With the update and progress of cardiac surgery technology, OPCABG has
been more and more favored by cardiac surgeons. Although the debating of
OPCABG and CABG remained, OPCABG has similar survival rate comparing
with CABG presently, and it shows great advantages for some older and
severe
patients1,2,36-39.
Since OPCABG does not require CPB, related complications such as
inflammation and blood cell destruction caused by CPB are avoided.
Additionally, in OPCABG surgeons performs coronary artery anastomosis on
a beating heart which requires very high surgical skills, and which also
poses greater challenges to the cooperation of anesthesiologists whose
intraoperative monitoring is vital. Anesthesia for cardiac surgery is
more challenging while OPCABG requires much higher for anesthesia.
Anesthesiologists must always monitor the vital signs of patients,
monitor hemodynamic changes, and cooperate with surgeons’ operations at
all times intraoperatively. Although diverse anaesthetic and sedative
analgesics have been used since modern times, intraoperative
complications are still
inevitable40-42.
Delirium is one of the common complications following cardiac surgery.
On account of sedation and mechanical ventilation are routinely required
after cardiac surgery, and most patients need vasoactive drugs to
stabilize vital signs, therefore the occurrence of delirium has
threatened the safety of patient
postoperatively6,43-46.
Delirious patients often remove intubation and infusion tubes from the
body, which seriously threatens the safety of patients’ lives. For the
occurrence of postoperative delirium, current research has confirmed
many factors including major bleeding during surgery, hemodynamic
instability, and the patient’s history of cerebrovascular
disease47-51. However,
there is still a lack of a systematic and effective prediction system,
thence it is of great significance to explore and study the prediction
scoring system for delirium following OPCABG.
The SAS score was mean to be used to assess the prediction of serious
complications after general and vascular surgery which includes EBL,
LMAP and LHR during anesthesia and shows a good predictive effect.
Several research groups noted that the SAS could accurately predict
postoperative complications in surgical subspecialties including
neurosurgery and
esophagectomy16,52-54.
In another report, stabilizing the vital signs during surgery improved
the surgical outcomes in major surgeries. However, whether SAS score has
similar predictive effect on the occurrence of delirium following
OPCABG, there are few studies at present. Therefore, we though to
explore whether the SAS intraoperative score has a good predictive
effect on patients following OPCABG.
In the present study, we included patients who underwent OPCABG surgery.
The SAS score was calculated by monitoring the patient’s anesthesia data
during the surgery. The incidence of postoperative delirium was observed
through the ICU trained
nurses47,55,56.
Through statistical analysis, we found that low SAS score is an
independent risk factor for delirium in OPCABG patients, with EBL and
LMAP within the three factors are the main influencing factors. In the
prediction model, we found that SAS has a high sensitivity and
specificity for predicting the occurrence of postoperative delirium,
which has a good warning effect on the prevention of high-risk patients
after surgery. In addition, we stratified according to the level of SAS,
and found that patients with a low score of 4 have a significantly
increased incidence of postoperative delirium, which also provides a
good significance for the postoperative monitoring of
patients16,25,29,57.
We thought that because most patients receiving OPCABG have severe
coronary calcification, and the vascular elasticity is significantly
reduced. Surgical manipulation on beating heart have a greater impact on
hemodynamics, usually causing blood pressure fluctuation drastically,
and minimum blood pressure may occur between 30-50mmHg. Consequently,
the occurrence of hypotension during OPCABG surgery significantly
reduced the SAS
score16,58-60.
In addition, although OPCABG does not require CPB, compared with other
general surgery, intraoperative blood loss also increased as a result of
greater trauma and heparinization. As for changes in heart rate,
patients on OPCABG had tachycardia occurred much more than bradycardia
because stimulating to the heart. Wherefore, the SAS score during the
operation reduced significantly during surgery which can be used to
predict postoperative complications such as delirium.
In conclusion, in this retrospective study, we found that for patients
underwent OPCABG, the intraoperative SAS score has a useful predictive
effect on the occurrence of delirium postoperatively and which shows
great correlation with delirium. The main limitation of this study is
its retrospective designing and lack of high level of evidence.
Secondly, we did not calculate the effect of intraoperative anesthetic
and postoperative sedation in this study, and a larger sample size study
is expected to draw more persuading conclusions.