Stump Pressure Measurements Research Articles

Carotid endarterectomy; A new center, two years results

Aim: We aimed to evaluate the demographic characteristics and early postoperative complications of patients who underwent conventional carotid endarterectomy (CEA) in a secondary level hospital retrospectively. Material and Methods: Forty-six patients who operated by a single surgeon at Sinop Ataturk State Hospital between January 2015 to December 2016 were included in the current study. Data regarding to demographic characteristics, symptoms, distribution of lesions, diagnostic methods, operation technique and early complications have been collected from handwritten and electronic clinical records. Results: The mean age was found as 70.9±9.7. Thirty patients were male. The most common risk factors were hypertension (93.5%), hyperlipidemia (50%), cigarette (41.3%) and diabetes (34.8%). Conventional CEA (CCEA) was performed to all patients. Patch plasty was applied to only one patient. According to the internal carotid artery stump pressure, T shunt was performed to 17.4% of patients. One patient died in early postoperative period because of myocardial infarction. In four patients; transient dysphagia, in three patients; hematoma requiring revision, in one patient; uncontrolled hypertension, and in one patients wound infection occurred. Furthermore, delirium occurred in one patient. Conclusion: Our experience CEA are compatible with the literature. Our results have supported that CCEA with measurement of carotid arter stump pressure are reliable surgical procedure for patients with carotid artery stenosis. Cardiac complications are rare but it can be mortal. Minor surgical complications are more common than death and stroke risk. However, close follow-up can prevent serious complications.

Comparing near-infrared spectroscopy monitoring and stump pressure measurement to estimate the need for shunting during carotid artery endarterectomy

Comparing near-infrared spectroscopy monitoring and stump pressure measurement to estimate the need for shunting during carotid artery endarterectomy

Identifying a Safe Carotid Stump Pressure Threshold for Selective Shunting During Carotid Endarterectomy

There is no current consensus on the best criteria for selective shunting during carotid endarterectomy (CEA). The choice of continuous neurologic assessment during awake CEA, intraoperative electroencephalogram, or carotid stump pressure monitoring as the basis for shunt placement is primarily dependent on surgeon preference. Our goal is to define a safe stump pressure threshold as a guide for selective shunting. The study is a single-surgeon retrospective review of consecutive patients who underwent CEA under general anesthesia with selective shunting based on intraoperative stump pressure measurements from 2001 to 2019. Demographic and periprocedural variables were analyzed using standard statistical techniques. Among 399 patients, 68% were male with a mean age of 70. One-third of the patients were symptomatic, with amaurosis fugax in 12%, transient ischemic attack in 7%, and stroke in 16%. In total, 60 (15%) patients underwent shunting: 34 for a confirmed preoperative acute ischemic stroke, 22 for a stump pressure <30mm Hg, and 4 for other indications. Overall 30-day death, ischemic ipsilateral stroke, myocardial infarction, and cranial nerve palsy rates were 0.5%, 0.8%, 1.8%, and 1.0%, respectively. No strokes occurred due to hypoperfusion, and all stroke symptoms resolved prior to discharge with a mean length of stay of 1.6days. This is one of the largest contemporary series of CEA using a 30mm Hg threshold for selective shunting that demonstrated exceedingly low 30-day death and stroke events. Intraoperative carotid stump pressure measurements are a useful guide for selective shunting and reduction in perioperative stroke complications after CEA.

Surgical Complications after Open Abdominal Aortic Aneurysm Repair: Intestinal Ischemia, Buttock Claudication and Sexual Dysfunction

While surgical treatment for abdominal aortic aneurysm (AAA) is a standard operation, prevention of complication is important. Intestinal ischemia of the sigmoid colon and/or rectum after AAA surgery is severe and has a high mortality rate although occurrence frequency is low. The most important thing to prevent is the preoperative and intraoperative evaluation of the left hemicolon and rectal circulation. Measurement of inferior mesenteric artery stump pressure is also useful. From the viewpoint of prevention of buttock claudication, it is desirable that internal iliac artery (IIA) blood flow is preserved, but aggressive IIA reconstruction adaptation is considered to be low. For erectile function, it is important that the antegrade blood flow from the IIA to the internal pudendal artery on at least one side is preserved or reconstructed. To prevent retrograde ejaculation, it is important to preserve the superior hypogastric plexus and one side of the lumbar splanchnic nerve, and the hypogastric nerve. Understanding and mastering local anatomy and pathophysiology is important in preventing complications, and we must also remember that we always keep watchful surgical operations in mind in order to prevent tissue damage. (This is a translation of Jpn J Vasc Surg 2019; 28: 99–103.)

Cerebral Neuromonitoring during Carotid Endarterectomy and Impact of Contralateral Internal Carotid Occlusion

The aim of this study was to identify the reliability of carotid artery stump pressure (SP) in predicting the neurologic changes and correlation with contralateral internal carotid artery (ICA) occlusion in patients undergoing eversion carotid endarterectomy (CEA). The optimal method for monitoring cerebral perfusion during CEA, performed under either local or general anesthesia, is still controversial. We prospectively analyzed 118 consecutive patients undergoing eversion CEA under local anesthesia. We had 78 symptomatic (66%) and 40 asymptomatic patients (33.9%). Selective shunting was performed in patients who developed neurologic changes after carotid clamping regardless of SP. Correlation of preoperative symptom status, a degree of stenosis, status of contralateral ICA, arterial blood pressure, SP value, and the intraoperative need for shunting due to neurologic changes was evaluated for both groups: shunted and nonshunted. Selective shunting was performed in 12 patients (10%). There was no significant difference among the groups regarding the demographic characteristics. Mean carotid clamping time was 14.57 minutes. We had no perioperative mortality, stroke, or myocardial infarction. None of the patients required conversion to general anesthesia. We found a mean SP of 31 mm Hg as a reliable threshold for shunting (P < .001; sensitivity 92.3%; specificity 91.3%). Contralateral carotid occlusion was correlated with the significantly lower SP (27 ± 13 mm Hg; P = .001) and the higher need for shunt (50%). SP measurement is a reliable and simple method for monitoring the collateral cerebral perfusion and can predict the need for shunting during CEA. Patients with the contralateral ICA occlusion showed significantly lower SP, although it did not have impact on the outcome.

Endarterectomía carotídea con medición de presión de muñón, manejo hemodinámico y uso selectivo de shunt

Introduction: During carotid endarterectomy (CEA) clamping cerebral perfusion is maintained by contralateral circulation through the Circle of Willis and it is correlated to the stump pressure (SP). If it is below 50 mmHg there is risk of stroke due to hypoperfusion and a shunt must be used, but systemic blood pressure can be temporarily elevated making the use of shunt unnecessary. Aim: Results of CEA with SP measurement to evaluate cerebral perfusion in cross-clamped hemisphere and hemodynamic intraoperative management reducing the use of shunt. Material and Methods: Retrospective study of CEAs performed in 73 patients under general anaesthesia with SP measurement, hemodynamic management and selective use of shunt. Demographics, clinical and perioperative morbimortality variables were analized. Results: 73 patients, average age 71.1 years, 69.9% symptomatic. In 54 patients SP was above 50 mmHg and shunt was not used, in 19 SP was below 50 mmHg, it was elevated through intraoperative hemodynamic management and shunt was not needed. In only 3 cases SP did not reach 50 mmHg and a Pruitt-Inahara shunt was used. Two patients presented postoperative transient central neurological deficit and 2 died due to myocardial infarction. Conclusion: CEA with SP measurement and hemodynamic management reduced the use of carotid shunting and it was a safe procedure to treat patients with severe carotid stenosis who need surgical intervention.

Combined Stump Pressure and Oximetry for Shunt Use During Carotid Endarterectomy.

Cross-clamp ischemia during carotid endarterectomy can be prevented with carotid bypass shunts in vulnerable patients identified by cerebral monitoring for ischemia. We compared transcranial cerebral oximetry (TCO) with carotid stump pressure measurements for selective shunt use. We prospectively collected data on 300 consecutive patients operated on under general anesthesia between 2009 and 2016. Shunts were inserted for a 10% or greater drop in cerebral saturations and/or a mean stump pressure less than 40 mmHg. Seventy-five patients, 25% of the study population, were shunted. The indication was a combined desaturation and stump pressure in 38 (50% of the shunted group), desaturation alone in 11 patients (15%), and a low stump pressure alone in 26 patients (35%). There were no significant differences in baseline characteristics between those patients who were or were not shunted, except angiographic collateral blood supply, which was more commonly identified in patients who were not shunted. A watershed infarct occurred in just one patient with borderline TCO and stump pressure measurements in whom a shunt was not used. There was poor concordance between TCO and stump pressures, but using both in determining the need for shunt use almost eliminated cross-clamp ischemia in this series of 300 carotid endarterectomy patients.

Cost-Effectiveness of Two Decision Strategies for Shunt Use During Carotid Endarterectomy

BackgroundArterial shunting during carotid endarterectomy (CEA) is essential in some patients because of insufficient cerebral perfusion during cross-clamping. However, the optimal diagnostic modality identifying these patients is still debated. None of the currently used modalities has been proved superior to another. The aim of this study was to assess the cost-effectiveness of two modalities, stump pressure measurement (SPM) versus electroencephalography (EEG) combined with transcranial Doppler (TCD) during CEA.MethodsTwo retrospective cohorts of consecutive patients undergoing CEA with different intraoperative neuromonitoring strategies (SPM vs. EEG/TCD) were analyzed. Clinical data were collected from patient hospital records. Primary clinical outcome was in-hospital stroke or death. Total admission costs were calculated based on volumes of healthcare resources. Analyses of effects and costs were adjusted for clinical differences between patients by means of a propensity score, and cost-effectiveness was estimated.ResultsA total of 503 (239 SPM; 264 EEG/TCD) patients were included, of whom 19 sustained a stroke or died during admission (3.3 vs. 4.2%, respectively, adjusted risk difference 1.3% (95% CI −2.3–4.8%)). Median total costs were €4946 (IQR 4424–6173) in the SPM group versus €7447 (IQR 6890–8675) in the EEG/TCD group. Costs for neurophysiologic assessments were the main determinant for the difference.ConclusionsGiven the evidence provided by this small retrospective study, SPM would be the favored strategy for intraoperative neuromonitoring if cost-effectiveness was taken into account when deciding which strategy to adopt.

Modifiable Factors Leading to Increased Length of Stay after Carotid Endarterectomy

Carotid endarterectomy (CEA) is a commonly performed vascular operation. Yet, postoperative length of stay (LOS) varies greatly even within institutions. In this study, the morbidity and mortality, as well as financial impact of increased LOS were reviewed to establish modifiable factors associated with prolonged hospital stay. The Society for Vascular Surgery Vascular Quality Initiative database was used to identify all patients undergoing primary CEA at a single institution between June 1, 2011 and November 28, 2014. Preoperative patient characteristics, intraoperative details, postoperative factors, long-term outcomes, and cost data were reviewed using an Institutional Review Board-approved prospectively collected database. Multivariate analysis was used to determine statistical difference between patients with LOS ≤1day and >1day. Complete 30-day variable and cost data were available for 219 patients with an average follow-up of 12months. Seventy-nine (36%) patients had an LOS>1day. Variables determined to be statistically significant predictors of prolonged LOS included preoperative creatinine (P=0.02) and severe congestive heart failure (P=0.05) with self-pay status (P=0.02) and preoperative beta-blocker therapy (P=0.04) being protective. Shunt placement (P=0.04), arterial re-exploration, and postoperative cardiac (P=0.001) or neurological (P=0.03) complications also resulted in prolonged hospitalization. Specific modifiable riskfactors that contributed to increased LOS included operative start time after noon (P=0.04), drain placement (P=0.05), prolonged operative time (101 vs. 125min, P=0.01), return to the operating room (P=0.01), and postoperative hypertension (P=0.02) or hypotension (P=0.04). Of note, there was no difference in LOS associated with technique (conventional versus eversion), patch use (P=0.49), protamine administration (P=0.60), electroencephalogram monitoring (P=0.45), measurement of stump pressure (P=0.63), Doppler (P=0.36), or duplex (P=0.92). Both hospital charges (P=0.0001) and costs (P=0.0001) were found to be significantly higher in patients with prolonged LOS, with no difference in physician charges (P=0.10). Increased LOS after CEA was associated with an increase in 12-month mortality (P=0.05). Increased LOS was associated with increased hospital charges, costs, as well as significant morbidity and midterm mortality following CEA. Furthermore, this study highlights several modifiable risk factors leading to increased LOS. Identified factors associated with increase LOS can serve as targets for improving care in vascular surgery.

P.118 An experience with combined cerebral oximetry and stump pressure measurement to guide shunt insertion during carotid endarterectomy

Background: Cross-clamp ischemia during carotid endarterectomy (CEA) can cause perioperative stroke. Selectively shunting patients based on intraoperative monitoring modalities that assess risk for ischemia can reduce the occurrence of immediate stroke. An experience with combined cerebral oximetry and stump pressure measurement to direct selective shunting is presented here. Methods: Study comparing intraoperative monitoring data, the decision to shunt, and presence of immediate post-operative deficits. Patients were shunted if either cerebral oxygen saturation dropped by more than 10% by cerebral oximetry, or stump pressure during cross-clamping was less than 40 mmHg. Cross-clamp ischemia was determined by the presence of ipsilateral neurological deficit upon awakening. Results: 245 patients were included in this study. 22% were shunted. Patients who were not shunted were significantly more likely to have collateral blood flow detected on angiography. Immediate post-operative stroke was not encountered in any of the patients included in the study. One patient who met shunting criteria but was excluded since he could not have a shunt inserted due to difficult anatomy did suffer stroke. Conclusions: With the dual-monitoring criteria presented here, 22% of patients were shunted. With the exception of one patient who could not have a shunt placed, no immediate post-operative stroke was encountered.

Dense Accumulation of Lipiodol Emulsion in Hepatocellular Carcinoma Nodule during Selective Balloon-occluded Transarterial Chemoembolization: Measurement of Balloon-occluded Arterial Stump Pressure

To reveal the mechanism of dense accumulation of lipiodol emulsion (LE) in hepatocellular carcinoma (HCC) during selective balloon-occluded transarterial chemoembolization (B-TACE). Balloon-occluded arterial stump pressure (BOASP) at the embolization portion was measured during selective B-TACE for 43 nodules in 42 patients. Fluoroscopy and digital subtraction angiography were prospectively observed during selective B-TACE to note whether dense LE accumulation in HCC occurred. The LE concentration ratio of HCC to embolized liver parenchyma (LECHL ratio) was also calculated for each treatment on the basis of the computed tomographic scan obtained immediately after selective B-TACE. The relationships between degree of LE accumulation and the BOASP, as well as the LECHL ratio, were analyzed. Arterial flow beyond the catheter tip was maintained even after balloon inflation. In 39 of 43 treatments, LE inflow into the nontumorous liver parenchyma ceased immediately after LE droplets were filled in arteries of the nontumorous liver parenchyma while LE inflow into the HCC nodule continued (group 1). More dense LE accumulation in HCC nodule was obtained in these 39 treatments. In four treatments, LE inflow both into the nontumorous liver parenchyma and into the HCC nodule continued, and no dense LE accumulation in HCC nodule was observed (group 2). In these four treatments, thick anastomotic vessels with collateral artery were noted. The BOASP in group 1 was (mean ± SD) 33.8 ± 12.8 mmHg (range 13-64 mmHg) and that in group 2 was 92.3 ± 7.4 mmHg (range 83-100 mmHg). There was a statistically significant difference in BOASP between groups (p = 0.00004, Welch's t test). The LECHL ratio in group 1 was 18.3 ± 13.9 (range 2.9-54.2) and that in group 2 was 2.6 ± 1.1 (range 1.7-4.2). There was a statistically significant difference in the LECHL ratio between the groups (p = 0.000034, Welch's t test). Selective B-TACE induced dense LE accumulation in HCC nodules in 39 (91 %) of 43 treatments in which BOASP was 64 mmHg or less.

Venous Angioplasty in Patients with Multiple Sclerosis: Results of a Pilot Study

Carotid artery stenosis is a complication of neck irradiation. We describe the immediate and long-term results of surgical treatment. This was a retrospective single centre study. From 1996 to 2009, 24 consecutive patients who had in the past received neck radiation therapy (mean 12 years, 1–41 years) underwent 27 primary carotid artery revascularisation procedures. Six patients (23%) had previous radical neck dissection, three permanent tracheostomies and one cervicoplasty with pectoral muscle flap. Indications for surgery included symptomatic (five transient ischaemic attacks (TIAs), four strokes; 34%) and asymptomatic (18 patients, 66%) stenosis. Four patients had occlusion of the contralateral carotid. General anaesthesia without shunting was used with measurement of stump pressure. Carotid interposition bypass grafting included 23 vein grafts and three Polytetrafluoroethylene (PTFE) grafts. No perioperative deaths or central neurological events occurred. Three patients suffered transient cranial nerve injuries. Eleven patients died during follow-up, mean interval of 28 months (range 6–120 months), of causes unrelated to surgery. Five patients had recurrent bypass stenosis with one TIA and one stroke. All other surviving patients remained asymptomatic. Despite no comparative study as evidence, we think that the perioperative risk of stroke is at least comparable with the risk encountered for angioplasty procedures.

Carotid Artery Revascularisation Following Neck Irradiation: Immediate and Long-Term Results

Objective Carotid artery stenosis is a complication of neck irradiation. We describe the immediate and long-term results of surgical treatment. Methods This was a retrospective single centre study. From 1996 to 2009, 24 consecutive patients who had in the past received neck radiation therapy (mean 12 years, 1–41 years) underwent 27 primary carotid artery revascularisation procedures. Six patients (23%) had previous radical neck dissection, three permanent tracheostomies and one cervicoplasty with pectoral muscle flap. Indications for surgery included symptomatic (five transient ischaemic attacks (TIAs), four strokes; 34%) and asymptomatic (18 patients, 66%) stenosis. Four patients had occlusion of the contralateral carotid. General anaesthesia without shunting was used with measurement of stump pressure. Carotid interposition bypass grafting included 23 vein grafts and three Polytetrafluoroethylene (PTFE) grafts. Results No perioperative deaths or central neurological events occurred. Three patients suffered transient cranial nerve injuries. Eleven patients died during follow-up, mean interval of 28 months (range 6–120 months), of causes unrelated to surgery. Five patients had recurrent bypass stenosis with one TIA and one stroke. All other surviving patients remained asymptomatic. Conclusion Despite no comparative study as evidence, we think that the perioperative risk of stroke is at least comparable with the risk encountered for angioplasty procedures.

Extracranial infected carotid artery aneurysm

Infected aneurysms of the extracranial carotid arteries are rare. This is a case report of a 63-year-old female who developed an infected internal carotid artery aneurysm due to group B Streptococcus ten days after a dental procedure. She was successfully treated with excision of the aneurysm and common to internal carotid artery bypass with greater saphenous vein.

Überwachung der zerebralen Integrität

In vascular surgery, intraoperative monitoring of the brain is recommended when the internal carotid artery (ICA) is clamped, because brain damage by ischemia and embolism is possible. Clamping of the ICA results in embolic or ischemic brain lesions in about 7 % of all patients undergoing the procedure. Prophylactic routine insertion of an intraluminal shunt can cause brain embolism and does not reduce the occurrence of complications. Consequently, a shunt should only be inserted, if critical reduction of cerebral perfusion is evident after clamping the ICA. Measurement of carotid stump pressure is an invasive method to estimate perfusion of the brain hemisphere at the clamping side. Transcranial doppler sonography (TCD) measures the mean blood flow velocity in the ACI, but practicability is suffering from technical problems in 20% of all patients. However, TCD is useful for detecting intraoperative embolism and postoperative hyperperfusion. Changes of oxyhaemoglobine and desoxyhaemoglobine concentration in brain tissue can be measured using near-infrared spectroscopy (NIRS) with wavelengths between 700 and 1000 nm. NIRS measurement is easily performed and reacts quickly to changes of brain tissue oxygenation, but there is still lacking evidence and at present a general recommendation of its application in vascular surgery is not justified. Use of somatosensory evoked potentials (SEP) is the most widespread cerebral neuromonitoring during vascular surgery due to its high reliability and simple application. Sensitivity and specifity for ischemic lesions are 100% and 94%-99%, respectively. SEP are regarded as the gold standard for cerebral neuromonitoring in anaesthetized patients.

Accuracy of Cerebral Monitoring in Detecting Cerebral Ischemia during Carotid Endarterectomy

This study compares the accuracy of cerebral monitoring systems in detecting cerebral ischemia during carotid endarterectomy. The authors compared transcranial Doppler sonography (TCD), near-infrared spectroscopy (NIRS), stump pressure (SP) measurement, and somatosensory evoked potentials (SEP) in 48 patients undergoing carotid surgery during regional anesthesia. Cerebral ischemia was assumed when neurologic deterioration occurred. During clamping, the minimum mean middle cerebral artery velocity (TCD(min)), its percentage change (TCD%), the minimum regional saturation of oxygen (NIRS(min)), its percentage change (NIRS%), the mean SP, and the changes of SEP amplitude were recorded. To analyze the corresponding sensitivity and specificity of each parameter, the authors performed receiver operating characteristic analysis. Neurologic deterioration occurred in 12 patients. SP and NIRS were successfully performed in all patients. TCD monitoring was not possible in 10 (21%); SEP was not possible in 2 patients (4%). All parameters provided the ability to distinguish between ischemic and nonischemic patients. TCD% and NIRS% showed significantly better discrimination than TCD(min) and NIRS(min) (P < 0.05). The highest area under the curve (AUC) was found for TCD% (AUC = 0.973), but there was no significant difference compared with NIRS% (AUC = 0.905) and SP (AUC = 0.925). The lowest AUC was found for SEP (AUC = 0.749), which was significantly lower than that for TCD%, NIRS%, and SP. TCD%, NIRS%, and SP measurement provide similar accuracy for the detection of cerebral ischemia during carotid surgery. Lower accuracy was found for SEP monitoring. Because of the high rate of technical difficulties (21%), TCD monitoring was the least practical of the investigated monitoring devices.

Stump Pressure and Somatosensory Evoked Potentials for Predicting the Use of Shunt During Carotid Surgery

The aim of this study is to compare measurement of stump pressure (SP) and somatosensory evoked potentials (SSEP) made during carotid surgery as criteria upon which to base the decision whether or not to use a shunt. We included 288 patients who underwent for carotid surgery under general anaesthesia. We performed 247 endarterectomies with patch closure (85.7%), 25 carotid transsection with reimplantation (8.7%), and 16 carotid bypasses (5.6%). SSEP monitoring showed no modification in 225/288 patients (78.1%), moderate modification in 32/288 patients (11.1%), and severe modification in 31/288 patients (10.8%). Shunt was used if there was moderate or severe SSEP modification in response to carotid clamping, which represents 63 patients in our series. A shunt was used in 47/288 patients (16.3%). In 16 patients, despite SSEP modifications, the shunt was not used because these SSEP modifications occurred only in the last minutes of the procedure just before off clamping the carotid. The mean SP for all patients was 51 mm Hg. In the shunted patients, the mean SP was 33 mm Hg. Variation of SP was correlated with the SSEP modifications. There was just one perioperative stroke in this series (1/288 = 0.3%). We concluded that the threshold of SP below which shunting is indicated in our study was 44 mm Hg with 81% sensibility and 68% specificity.

Prospective evaluation of electroencephalography, carotid artery stump pressure, and neurologic changes during 314 consecutive carotid endarterectomies performed in awake patients

This study attempted to correlate neurologic changes in awake patients undergoing carotid endarterectomy (CEA) under cervical block anesthesia (CBA) with electroencephalography (EEG) and measurement of carotid artery stump pressure (SP). Continuous EEG and SP monitoring was measured prospectively in 314 consecutive patients undergoing CEA between April 1, 2003, and July 30, 2006, under CBA. Indications for CEA were asymptomatic 70% to 99% internal carotid artery stenosis in 242 (77.1%), transient ischemic attacks (including transient monocular blindness) in 45 (14.3%), and prior stroke in 27 (8.6%). Mean common carotid artery pressure before clamping, mean SP after carotid clamping, and intraarterial pressure were continuously monitored in all patients. An indwelling shunt was placed when neurologic events (contralateral motor weakness, aphasia, loss of consciousness, or seizures) occurred, regardless of SP or EEG changes. Shunt placement was necessary because of neurologic changes in 10% (32/314) of all CEAs performed under CBA. Only 3 patients (1.4%) of 216 required shunt placement if SP was 50 mm Hg or more, vs 29 (29.6%) of 98 if SP was less than 50 mm Hg (P < .00001; sensitivity, 29.8%; specificity, 98.6%). In patients with SP of 40 mm Hg or more, 7 (2.6%) of 270 required shunt placement, vs 25 (56.8%) of 44 if SP was less than 40 mm Hg (P < .00001; sensitivity, 56.8%; specificity, 97.4%). Ischemic EEG changes were observed in 19 (59.4%) of 32 patients (false-negative rate, 40.6%) requiring shunt placement under CBA. Three patients had false-positive EEG results and did not require shunt placement (false-positive rate, 1.0%). The perioperative stroke/death rate was 4 (1.2%) in 314. All strokes occurred after surgery and were unrelated to cerebral ischemia or lack of shunt placement. Ten percent of patients required a shunt placement during CEA under CBA. Shunt placement was necessary in 56.8% of patients with SP less than 40 mm Hg. EEG identified cerebral ischemia in only 59.4% of patients needing shunt placement, with a false-positive rate of 1.0% and a false-negative rate of 40.6%. Both SP and EEG as a guide to shunt placement have poor sensitivity. Intraoperative monitoring of the awake patients under regional anesthesia (CBA) is the most sensitive and specific method to identify patients requiring shunt placement.

Cerebral oxygen saturation, transcranial Doppler ultrasonography and stump pressure in carotid surgery.

Transcranial Doppler ultrasonography (TCD) of the middle cerebral artery (MCA), light-reflective cerebral oximetry and measurement of internal carotid artery stump pressure were compared as methods of monitoring cerebral perfusion during carotid surgery in 33 patients. Median cerebral oxygen saturation was 70 (range 62-85) per cent and TCD-measured mean blood velocity 42 (range 19-91) cm/s before carotid cross-clamping, falling to 68 (53-83) per cent and 16 (0-50) cm/s respectively on application of the clamps (P < 0.001). Stump pressure correlated closely with MCA blood velocity 30 s after the start of cross-clamping (rs = 0.58, P < 0.001), but not with cerebral oxygen saturation. A fall of 5 per cent or more in cerebral oxygen saturation following cross-clamp application was predicted by a decrease in mean MCA blood velocity of at least 60 per cent. Changes in cerebral oxygen saturation correlated significantly with systolic blood pressure throughout the perioperative period (rs = 0.41, P < 0.001). Significant falls in cerebral oxygenation were not predicted by low stump pressure but were associated with large reductions in the mean MCA blood velocity measured by TCD.

Correlation of carotid artery stump pressure and neurologic changes during 474 carotid endarterectomies performed in awake patients

A carotid artery stump pressure (SP) of < 50 mm Hg and abnormal electroencephalography (EEG) changes have been suggested as indications for selective shunting in patients undergoing carotid endarterectomy (CEA) under general anesthesia. We attempted to determine the optimal SP threshold that correlated with neurologic changes in awake patients undergoing CEA using cervical block anesthesia (CBA) and performed a cost comparison with EEG monitoring. Between July 1, 1995, and December 31, 2004, SP was measured during 474 CEAs performed under CBA by inserting a 19-gauge butterfly needle into the common carotid artery. A saline-filled intravenous bag in the patient's contralateral hand was connected to pressure tubing to generate waveforms with hand squeezing that could be visualized on a monitor. Systemic pressure was maintained approximately 10 mm Hg higher than baseline. Accurate SPs were confirmed by the finding of flatline waveforms after internal carotid artery clamping. Selective shunting was performed when neurologic changes occurred (aphasia, inability to squeeze the contralateral hand, decreased consciousness), regardless of SP. During this same period, 142 patients underwent CEA using GA, and SP was also measured. Shunting was necessary because of neurologic changes in 7.2% (34/474) of all CEAs performed using CBA: 0.9% (3/335) with SPs > or = 50 mm Hg systolic vs 1.0% (4/402) with SPs > or = 40 mm Hg systolic, and 22% (31/139) with SPs < 50 mm Hg systolic vs 42% (30/72) with SPs < 40 mm Hg systolic. If these 474 CEAs had been performed using GA, shunts would have been used in 29% (139/474) of patients for a SP < 50 mm Hg systolic vs 15% (72/474) for a SP < 40 mm Hg systolic. In patients not shunted, the perioperative stroke/death rate was 1.2% in patients (4/332) with SPs > or = 50 mm Hg vs 1.0% (4/398) with SPs > or = 40 mm Hg. Three of the four strokes occurred > 24 hours postoperatively and were unrelated to lack of shunting and ischemia. There was no significant difference in the percentage of patients with SPs > or = 50 mm Hg who underwent CEA using CBA (70%, 335/474) vs GA (67%, 96/142) during this time period. At our hospital, charges for SPe measurement, including anesthesia charges and tubing, were 229 dollars per case vs 3439 dollars per case for EEG monitoring. Use of SP measurements in these 474 patients would have resulted in reduced charges of 1,521,540 dollars compared with EEG monitoring if CEA had been performed under GA. Using 40 mm Hg systolic as a threshold, the need for shunting (15%) and the false-negative rate (1.0%) for SP in our series were equivalent to the results of EEG monitoring during CEA reported in the literature. However, charges for SP measurements are dramatically lower compared with EEG monitoring. Our results suggest that a carotid artery SP > or = 40 mm Hg systolic may be considered as an equally reliable but more cost-effective method to predict the need for carotid shunting during CEA under GA compared with EEG monitoring, but further investigation is warranted.