Strategy Of Ultrasound In Surgical Safety Warning And Optimization

ObjectCarotid endarterectomy has been proved a standard intervention for moderate-to-severe symptomatic and selected severe asymptomatic carotid stenosis. But its beneficial effects are limited by the perioperative complications. Cerebral monitoring and prediction of related complication play an important role in reducing the perioperative risk. This study was designed to research whether blood pressure would influence the accuracy of Stump pressure (SP) as a monitoring indicator of intraoperative hypoperfusion. We also attempted to find the risk factors of intraoperative hypoperfusion.MethodWe held a prospective clinical trial by recuiting176patients who underwent CEA under general anesthesia from2009to2012. Continuous TCD monitoring was performed during operation with measurement of MCAV. Systemic blood pressure (BP) was recorded at the same time. Stump pressure was recorded after clumping the carotid arteries. Shunting was used selectively. CT or MRI was performed if the neural symptoms happened. We analyzed the relationship between SP and MCAV. SP was compared with stump pressure index (SSI) to verify whether the SP should be corrected by systemic blood pressure. Multivariate logistic regression was used to find the risk factors of intraoperative hypoperfusion.Results1. There was no linear relationship between SP and MCAV during clamping (r=0.448, p<0.001). If the MCAV values were expressed as relative change of pre-clamping values, the correlation coefficient was still small (r=0.424, p<0.001).2. There were15patients whose MCAVs were reduced to0after clamping. The analysis demonstrated that these patients had more risk of postoperative TIA. There were14patients whose MCAVs after clamping were greater than the velocities before clamping. These patients did not show more risks of postoperative complications. However other researches pointed out that this kind of patients might have more postoperative risks.2. The AUCs of SP and SSI are both more than0.7. They are both accurate indicators in estimating intraoperative hypoperfusion. But there was no obvious difference between SP and SSI. It demonstrated that the fluctuation of intraoperative blood pressure had little effect on the accuracy of SP in estimating intraoperative hypoperfusion. So the blood pressure elevation after clumping the carotid would not influence the application of SP. However our research demonstrated that the patients would have more risk of cerebral hyperperfusion syndrome if the blood pressure after clamping was more than160%of the pre-clamping blood pressure.3. Compared with preoperative clinical factors, hyperlipidaemia and age showed the differences between the hypoperfusion group and the normal group (p<0.05). However the logistic regression results demonstrated that only age≥60was the risk factor of intraoperative hyperperfusion (p<0.05). The p value of hyperlipidaemia was more than0.05.ConclusionSSI was not superior to SP in estimating intraoperative hypoperfusion. SP was an accurate indicator under general anesthesia. If we took SP as a criterion of hyperperfusion, it was not necessary to correct SP by systemic blood pressure. We suggested that the blood pressure after clamping should not be higher than160%of the pre-clamping blood pressure. We also suggested TCD monitoring in evaluating intraoperative hypoperfusion under general anesthesia. It was meaningful to take SP as a criterion when some patients could not receive TCD monitoring. We should pay great attention to the patients whose clamping MCAV was0or greater than the pre-clamping MCAV during TCD monitoring.