Carotid endarterectomy: perioperative and anesthetic considerations

Pulse pressure variation and stroke volume variation to predict fluid responsiveness in patients undergoing carotid endarterectomy

Background

During carotid endarterectomy (CEA), hemodynamic stability and adequate fluid management are crucial to prevent perioperative cerebral stroke, myocardial infarction and hyperperfusion syndrome. Both pulse pressure variation (PPV) and stroke volume variation (SVV), dynamic preload indices derived from the arterial waveform, are increasingly advocated as predictors of fluid responsiveness in mechanically ventilated patients. The aim of this study was to evaluate the accuracy of PPV and SVV for predicting fluid responsiveness in patients undergoing CEA.

Methods

Twenty seven patients undergoing CEA were enrolled in this study. PPV, SVV and cardiac output (CO) were measured before and after fluid loading of 500 ml of hydroxyethyl starch solution. Fluid responsiveness was defined as an increase in CO ≥ 15%. The ability of PPV and SVV to predict fluid responsiveness was assessed using receiver operating characteristic (ROC) analysis.

Results

Both PPV and SVV measured before fluid loading are associated with changes in CO caused by fluid expansion. The ROC analysis showed that PPV and SVV predicted response to volume loading (area under the ROC curve = 0.854 and 0.841, respectively, P < 0.05). A PPV ≥ 9.5% identified responders (Rs) with a sensitivity of 71.4% and a specificity of 90.9%, and a SVV ≥ 7.5% identified Rs with a sensitivity of 92.9% and a specificity of 63.6%.

Conclusions

Both PPV and SVV values before volume loading are associated with increased CO in response to volume expansion. Therefore, PPV and SVV are useful predictors of fluid responsiveness in patients undergoing CEA.

Vascular surgery, ICU and HDU: a 14-year observational study

INTRODUCTION

Over the course of the past decade, numerous changes have occurred in the management of patients undergoing vascular surgical operations. The introduction of high dependency units (HDUs) has meant that many patients previously requiring observation in intensive care units (ICUs) are now managed in this new environment. In addition, many vascular patients may now be suitable for management on a vascular ward immediately following their surgery. This study reports the chronological changes in resource utilisation of patients undergoing major vascular surgery in a district general hospital over a 14-year period.

PATIENTS AND METHODS

Details of all patients admitted to either the ICU or HDU under the care of a single vascular surgeon during the period 1991-2004 were extracted from a prospectively maintained anaesthetic department database. Details of the age and gender of the patients were obtained together with source of admission, place of discharge and need for re-admission. Operative details for each patient were extracted from a prospectively maintained vascular surgery database including type of procedure undertaken and degree of urgency.

RESULTS

During the 14-year period under study, there was a dramatic decrease in the use of ICU facilities for the management of vascular patients from 100% in 1991 to 36% in 2004. There was a corresponding increase in the use of HDU for major vascular cases during the same period from 0% to 66%. However, despite a significant increase in the total number of major vascular operations performed, from 67 in 1991 to 185 in 2004 as a result of sub-specialisation, overall use of all high-care facilities fell as the number of patients returned directly to the vascular ward increased from 34% in 1991 to 64% in 2004. The efficacy of the choice of management venue was confirmed by the observation that only 7.7% of those managed on ICU had been initially managed at a lower level of care. In addition, only 1.8% of patients managed on HDU had been admitted after initially being managed on the vascular ward.

CONCLUSIONS

Sub-specialisation over the past decade has meant a significantly increased major vascular work-load. Since the introduction of the HDU, there has been a significant fall in the use of ICU facilities for routine cases. These changes in resource utilisation have significant implications in terms of budget allocation. It would appear that finances, in relation to vascular surgery, should be concentrated on expanding HDU facilities and ensuring vascular surgery expertise amongst ward nursing staff.

Regional anaesthesia for carotid endarterectomy: an audit over 10 years

BACKGROUND

The aim of this retrospective study was to compare the failure rates and the frequency of anaesthesia-related complications of two different methods of regional anaesthesia used for carotid endarterectomy--cervical epidural (CE) anaesthesia and cervical plexus block (CPB).

METHODS

The study included 1828 carotid endarterectomies performed in 1455 patients between 1996 and 2006. A combination of deep and superficial CPB was used for 1166 procedures, whereas in 662 cases surgery was performed under CE anaesthesia.

RESULTS

The failure rate of CPB was 3% compared with 6.9% for CE anaesthesia (P < 0.0001). The reasons for failure of the anaesthetic techniques were (1) technical failure, (2) insufficient analgesia, (3) non-compliant patients, and (4) anaesthetic complications. The incidence of complications resulting from CE anaesthesia was significantly higher than with CPB; life-threatening complications--2% compared with 0.3% (P < 0.0001); other anaesthesia-related complications 5.7 vs 4.7%. Serious complications included inadvertant injection into the subarachnoid space or vertebral artery. The frequency of shunt insertion, perioperative stroke, and death from any cause was similar in both groups of patients.

CONCLUSIONS

Both methods of regional anaesthesia are acceptable for carotid artery surgery. CPB is associated with a significantly lower frequency of anaesthesia-related complications and should therefore be considered the anaesthetic of choice. CE anaesthesia should not be performed except in extenuating circumstances such as variant anatomy or the requirement for more extensive surgery.

Regional versus general anesthesia

The debate continues as to whether regional anesthesia is safer than general anesthesia. However, the choice of anesthetic technique is a complex decision. This review of the most recent publications compares the safety of regional anesthesia with that of general anesthesia.

Altered Autonomic Cardiovascular Regulation After Combined Deep and Superficial Cervical Plexus Blockade for Carotid Endarterectomy

Compromised cardiac autonomic modulation can produce cardiovascular disturbances. We investigated whether combined deep and superficial cervical plexus (CP) blockade for carotid endarterectomy (CEA) produces changes in autonomic cardiovascular regulation. To estimate alterations in cardiovascular autonomic control before and after combined CP blockade in 22 patients undergoing CEA, the heart rate (HR) variability, systolic blood pressure (SBP) variability, and baroreflex sensitivity were analyzed. We found that SBP (157 +/- 28 mm Hg versus 191 +/- 38 mm Hg before and after combined CP blockade, respectively) and HR (68 +/- 10 bpm versus 84 +/- 9 bpm) increased after combined CP blockade. The high frequency power of HR variability (3.7 +/- 0.9 versus 2.2 +/- 1.2 ln/ms2) decreased (decrease in parasympathetic drive), whereas the low frequency power of SBP variability (5.5 +/- 4.7 versus 8.6 +/- 9.4 mm Hg2) increased (increase in vascular sympathetic outflow). Baroreflex sensitivity decreased, and this decrease was negatively correlated with a SBP increase (r = -0.455). The present results suggest that combined CP blockade impairs autonomic cardiovascular homeostasis and suggests an association between combined CP blockade and intraoperative or postoperative adverse cardiovascular events in high-risk cardiac patients undergoing CEA that merits further studies.

Comparison of short-term clinical postoperative outcomes in patients who underwent carotid endarterectomy: Intensive care unit versus the ward high-dependency unit

The objective of this research was to examine the routine postoperative management of patients who have undergone carotid endarterectomy and compare the intensive care unit (ICU) with the ward high-dependency unit (HDU) in terms of the number, type, severity, or management of postoperative clinical events within a 48-hour time frame. Two of the vascular surgeons routinely admitted patients to the ICU, and 1 vascular surgeon routinely admitted patients to the ward HDU. This research determines whether there was a difference in outcomes between the 2 groups with the intention of changing the practice of the 2 vascular surgeons who routinely admitted their patients to the ICU. This was a nonexperimental, descriptive, prospective study of all patients who underwent carotid endarterectomy during an 18-month period between August 1999 and January 2000. A total of 104 patients were recruited to the study. There were 84 patients in the ICU cohort; 59 were male and 25 were female, with a mean age of 72 years. There were 20 patients in the ward HDU cohort; 12 were male and 8 were female, with a mean age of 66 years. Major complications occurred in 3 patients. One patient from the ICU group was returned to the operating room for evacuation of a hematoma, and 2 patients from the ward HDU group were transferred to the ICU for an inotropic infusion. During the first 24 hours, hypertension developed in 37 patients in the ICU cohort, 12 of whom did not require intervention. Hypertension requiring intervention developed in 3 patients in the ward group. Chi-square cross-tabulation revealed a chi 2 value of 1.4 and a P value of.01, which is a significant difference in the number of hypertensive events in the ICU versus the ward HDU. Hypotension occurred in 41 patients in the ICU group and in 9 patients in the ward cohort. The same chi 2 test was used to reveal a chi 2 value of 0.026 and a P value of.87, which are nonsignificant results. There was no difference in the number of hypotensive events in the ICU versus the ward HDU. There were no reported incidents of tachycardia. Bradycardia was reported in 64 patients in the ICU group and in 12 patients in the HDU group. There was no significant difference in the number of patients with bradycardia in either group of patients. Chi-square analysis revealed a chi 2 value of 1.4 and a P value of.23 during the first 24 hours postoperatively. We believe that careful selection of patients to the ward HDU is safe and cost-effective.

Choice of anesthetics

The choice of anesthetics for vascular surgical patients is not only determined by the kind and extent of the surgical procedure but also by patient comorbidities. Frequently, patients have a history of hypertension, peripheral vascular and coronary artery disease,cerebrovascular disease, and renal impairment. The goal of the chosen anesthetic technique is to protect organ function, mainly of the brain and the heart. In some instances regional anesthesia might be preferred, but no difference in outcome between the two techniques has been shown conclusively. Vascular emergencies are particularly challenging for the anesthesiologist, but in recent years the development of stent graft insertion has improved the short-term outcome in many of these procedures.

Risk factors for perioperative myocardial ischemia in carotid artery endarterectomy

OBJECTIVE

To identify variables associated with perioperative myocardial ischemia in patients undergoing carotid artery endarterectomy (CEA).

DESIGN

Prospective, observational study.

SETTING

University-affiliated hospital operating room and intensive care unit.

PARTICIPANTS

One hundred twenty-eight consecutive patients who underwent CEA during a 7-year period.

INTERVENTIONS

Patients had general anesthesia with sevoflurane or isoflurane. CEA was performed by standard methods with shunting if clinically indicated. Holter electrocardiogram (ECG) monitoring was performed during surgery and 24 hours after surgery.

MEASUREMENTS AND MAIN RESULTS

The incidence of perioperative myocardial ischemia was examined, and perioperative risk factors were analyzed. Nineteen patients (15%) showed significant perioperative ECG abnormalities indicative of myocardial ischemia (10 patients during surgery, 12 patients after surgery, and 3 patients both during and after surgery). Multivariate analysis showed perioperative myocardial ischemia to be significantly associated with a history of angina (odds ratio, 11.68; 95% confidence interval, 2.64-51.70) and a history of hypertension (odds ratio, 14.08; 95% confidence interval, 1.51-131.04).

CONCLUSION

The data indicate that perioperative myocardial ischemia defined as an ECG abnormality does not often occur in patients undergoing CEA. However, angina and hypertension may be important risk factors warranting further investigation.

Comparation of influence general and regional anesthesia on basic haemodynamic parameters during carotid endarterectomy

Carotid endarterectomy (CEA) is a preventive operation to reduce the incidence of embolic and thrombotic cerebral stroke. CEA carries a significant perioeperartive mortality rate from stroke and myocardial infarction, which may even approach 5%. Thus, anesthetic and surgical techniques are constantly under scrutiny to try to reduce this relatively high incidence of morbidity and mortality. Anesthetic technique for CEA is divided to general (GA) and regional (RA) anesthesia, performed by cervical plexus block. The aim this study was to examine changes of basic haemodynamic parameters, which routinely fallows during CEA in condition of GA and RA. After obtaining institutional approval and informed consent, we randomized 50 patients scheduled for CEA (Tab.1) in two groups (GA and RA). We fallow blood pressure: systolic (BPs), mean (BPm), diastolic (BPd), heart rate (HR), and RPP index at the examined patients. The examination performed in six control times: before induction of anesthesia (T1), 10 minutes after beginning of operation (T2), 5 minutes after cross clamping of arteria carotis (T3), 5 minutes after declamping arteria carotis (T4), 10 minutes (T5) and 2 hours after operation (T6). The results of study shows significant changes of blood pressure (BPs and BPm) and RPP index in T2 time in patinets undergoing GA. The changes occurred under influence of induction agent thio- pental. These changes were in homeostatic range. In RA patinets, no haemodynamic changes registrated in control times. Therefore, from haemodynamic aspect RA was superior to GA.

Hemodynamic stability, myocardial ischemia, and perioperative outcome after carotid surgery with remifentanil/propofol or isoflurane/fentanyl anesthesia

This study compares remifentanil/propofol (remi/prop) with isoflurane/fentanyl (iso/fen) anesthesia to determine which provides the greater hemodynamic stability, lesser myocardial ischemia, and morbidity with better postoperative outcomes after carotid endarterectomy. Sixty patients undergoing unilateral carotid endarterectomy were randomized to receive either a remi/prop or iso/fen anesthetic. Hemodynamic variables were recorded during the surgical procedure. In addition, transesophageal echocardiography was used to assess evidence of intraoperative regional wall motion abnormalities suggestive of cardiac ischemia. Emergence and extubation times, recovery from anesthesia, hemodynamic instability, nausea, vomiting, and pain in post anesthesia recovery, discharge delays, ICU admittance, hospital discharge, and preoperative and postoperative troponin levels were compared using appropriate statistical methods with P < 0.05 considered significant. The groups were demographically alike. Hemodynamic variables were similar during intubation and throughout surgery. Twenty-two percent of patients receiving iso/fen developed intraoperative regional wall motion abnormalities suggestive of ischemia, whereas no remi/prop patients had changes (P < 0.05). There was no difference in ST-T wave changes after surgery, and no patient had an elevation in troponin I levels. Postoperative variables were similar except that patients who received iso/fen had lower Stewart recovery scores during the first 15 minutes after post anesthesia care unit admission and a higher incidence of nausea and vomiting the day after surgery, whereas patients receiving remi/prop had discharge delays secondary to hypertension. ICU admittance, time to first void, oral intake, and time to hospital discharge were similar between the groups. At 9 times the cost of an iso/fen anesthesia technique, remi/prop offers little advantage over inhalational anesthesia for carotid endarterectomy.

The continuous recording of blood pressure in patients undergoing carotid surgery under remifentanil versus sufentanil analgesia

We compared the hemodynamic stability during carotid endarterectomy of remifentanil with that of sufentanil anesthesia. Fifty-six patients were randomly assigned into Remifentanil (n = 27) or Sufentanil (n = 29) groups. In the Remifentanil group, IV propacetamol (2 g) and morphine (0.1 mg/kg) were infused 30 min before skin closure. In the Sufentanil group, patients received 2 g propacetamol. Beat-to-beat recordings of systolic arterial blood pressure (SBP) and heart rate (HR) were stored on a computer. The maximum and minimum values of BP and HR after induction, at intubation, during the surgical procedure, and after the operation and the coefficients of variation of SBP and HR were used as indices of hemodynamic stability. The coefficients of variation of SBP and HR were similar in both groups during and after surgery. However, at intubation, maximal SBP was higher in the Sufentanil group (P < 0.05). Decreased propofol doses and isoflurane end-tidal concentrations were used in the Remifentanil group. At recovery, a similar profile of SBP and HR was found in both groups. We conclude that intra- and posthemodynamic stability was similar with remifentanil or sufentanil in patients undergoing carotid endarterectomy. However, remifentanil was more effective for blunting the increase in SBP at intubation without increasing the blood pressure-decreasing effect of induction. Intraoperative remifentanil use was associated with a decreased amount of hypnotic drug administered.

IMPLICATIONS

Beat-to-beat recordings of heart rate and blood pressure in patients undergoing carotid surgery revealed that hemodynamic stability was similar with remifentanil or sufentanil anesthesia both during and after surgery. Remifentanil was more effective in limiting the increase in blood pressure associated with intubation without increasing the blood pressure-lowering effect of induction or the blood pressure response to recovery.

Recovery and neurological examination after remifentanil-desflurane or fentanyl-desflurane anaesthesia for carotid artery surgery

We studied 44 patients undergoing carotid endarterectomy (CEA) to compare recovery after general anaesthesia with desflurane supplemented with either remifentanil or fentanyl. Remifentanil was infused at 0.1 microg kg(-1) min(-1) and desflurane was adjusted at 2 vol% end-tidal. Fentanyl was given as a bolus dose of 2 microg kg(-1) before induction and repeated at skin incision; desflurane was adjusted as needed. Times for early recovery and response to simple neurological tests (digit symbol substitution test (DSST) and Trieger dot test (TDT)) were measured 30, 60 and 90 min after operation. Emergence from remifentanil-desflurane anaesthesia was significantly quicker than that from fentanyl-desflurane anaesthesia: mean times to extubation were 4.1 (SD 1.7) and 8.2 (4.9) min, respectively; mean times for patients to state their name correctly were 6.0 (2.8) and 13.8 (9.0) min, respectively. Patients in the remifentanil-desflurane group successfully performed neurological tests significantly earlier than those in the fentanyl-desflurane group; for example, patients in the former group completed the arm holding test at 7.9 (3.0) min, while those in the latter group did this at 20.6 (19.7) min (P < or = 0.01). Intermediate recovery was less impaired at 30 min (DSST, TDT) and at 60 min (DSST). More rapid awakening and an earlier opportunity for neurological examination suggest that remifentanil-desflurane is a suitable alternative to a standard fentanyl-based general anaesthetic technique in patients undergoing CEA.

Carotid endarterectomy in an awake patient with contralateral carotid occlusion: influence of selective shunting

The objectives of this study were to determine whether the presence of a contralateral carotid occlusion increases risk and whether the perioperative results are influenced by a systematic or selective policy of shunting during carotid endarterectomy (CEA) in an awake patient. In a retrospective study we compared patients with and without contralateral carotid occlusion (group I, n = 198 - group II, n = 1068) who required CEA. In 77 patients of group I, a shunt was systematically adopted (subgroup A); in the other 121 patients (subgroup B) and in all patients of group II a selective shunting policy was adopted. The risk for the patients with contralateral carotid occlusion was not significantly higher than that for patients without occlusion. Results were not influenced by systematic/selective shunting policy, and the incidence of signs of cerebral ischemia was higher in patients with contralateral carotid occlusion.

Locoregional versus general anesthesia in carotid surgery: is there an impact on perioperative myocardial ischemia? Results of a prospective monocentric randomized trial

PURPOSE

The incidence of cardiac morbidity and mortality in patients who undergo carotid surgery ranges from 0.7% to 7.1%, but it still represents almost 50% of all perioperative complications. Because no data are available in literature about the impact of the anesthetic technique on such complications, a prospective randomized monocentric study was undertaken to evaluate the role of local anesthesia (LA) and general anesthesia (GA) on cardiac outcome.

METHODS

From November 1995 to February 1998, 107 patients were classified by the cardiologist as cardiac patients (IHD; history of myocardial infarction, previous myocardial revascularization procedures, or myocardial ischemia documented by means of positive electrocardiogram [ECG] stress test results) or noncardiac patients (NIHD; no history of chest pain or negative results for an ECG stress test). The patients were operated on after the randomization for the type of anesthesia (general or local). Continuous computerized 12-lead ECG was performed during the operative procedure and 24 hours postoperatively. The end points of the study were ECG modifications (upsloping or downsloping more than 2 mm) of the sinus tachycardia (ST) segment.

RESULTS

Fifty-five patients were classified as IHD, and 52 were classified as NIHD. Twenty-seven of the 55 IHD patients (49%) and 24 of 52 NIHD patients (46%) were operated on under GA. Thirty-six episodes of myocardial ischemia occurred in 22 patients (20.5%). Episodes were slightly more frequent (58%) and longer in the postoperative period (intraoperative, 10 +/- 5 min; postoperative, 60 +/- 45 min; P <. 001). As expected, the prevalence of myocardial ischemia was higher in the group of cardiac patients than in noncardiac group (15 of 55 patients [27%] vs 7 of 52 patients [13%]; P <.02). By comparing the two anesthetic techniques in the overall population, we found a similar prevalence of patients who had myocardial ischemia (GA, 12 of 52 [23%]; LA, 10 of 55 [18%]; P = not significant) and a similar number of ischemic episodes per patient (GA, 1.5 +/- 0.4; LA, 1.8 +/- 0.6; P = not significant). Episodes of myocardial ischemia were similarly distributed in intraoperative and postoperative periods in both groups. It is relevant that under GA, IHD patients represent most of the population who suffered myocardial ischemia (83%). On the contrary, in the group of patients operated on under LA, the prevalence was equally distributed in the two subpopulations.

CONCLUSION

The results confirm the different hemodynamic impact of the two anesthetic techniques. Patients who received LA had a rate of myocardial ischemia that was half that of patients who had GA. The small number of cardiac complications do not permit us to make any definitive conclusion on the impact of the two anesthetic techniques on early cardiac morbidity, but the relationship between perioperative ischemic burden and major cardiac events suggests that LA can be used safely, even in high-risk patients undergoing carotid endarterectomy.

Influence of the status of the contralateral carotid artery on the outcome of carotid surgery

From 1985 to 1995, 747 carotid arteries were operated on in 694 patients, who were under general anesthesia and continuous electroencephalogram (EEG) monitoring. These patients were divided into three groups according to contralateral carotid status. Group 1 consisted of 58 patients who had contralateral occlusion; group 2, 53 patients who had contralateral stenosis and bilateral staged surgery; and group 3, 583 patients who had nonstenotic contralateral internal carotid artery. All groups were similar with regard to age and sex ratio. There were more asymptomatic patients in group 3 than in group 1 (39.9% vs. 25.8%) (p < 0.05), and less preoperative strokes in group 2 than in the other groups (3.7% vs. 17.2% and 13. 6%, respectively) (p < 0.05). Among risk factors, smoking was less frequent in group 3 (59.5%) than in group 1 (82.7%) and group 2 (77%) (p < 0.01), and coronary artery disease was more frequent in group 2 (60%) than in group 1 (32.7%) and Group 3 (26.4%) (p < 0.01). EEG changes occurred more frequently in group 1 (25.8%) than in group 2 [5.6% (first stage) and 3.8% (second stage)] and in group 3 (4.9%) (p < 0.01). A shunt was used only when EEG changes did not disappear after pharmacologic increasing of central blood pressure, which occurred more frequently in group 1 (10.3%) than in group 2 (0%) and group 3 (0.3%) (p < 0.05). The combined morbidity/mortality rate was similar for groups 1 and 3 (1.7% and 1.5%, respectively), however, transient morbidity was more frequent in group 1 (6.9%) than in group 3 (1.5%) (p < 0.05). The combined morbidity/mortality rate was higher in group 2 than in group 3 (7.5% vs. 1.5%) (p < 0. 05), and all strokes in group 2 were seen during the second-stage operation. In conclusion, contralateral carotid artery occlusion had minimal influence over carotid surgery results. Selective use of a shunt based on EEG monitoring prevented ischemic strokes, with minimal neurologic morbidity. Contralateral carotid stenosis did not affect operative strategy for first stage, but we noted a higher incidence of strokes during the second procedure.

Incidence of phrenic nerve block and hypercapnia in patients undergoing carotid endarterectomy under cervical plexus block

Deep cervical plexus blockade blocks the second, third and fourth cervical nerve roots. The phrenic nerve arises from C3, C4, C5 and should therefore be commonly blocked with cervical plexus blockade. The aim of this study was to report the incidence of phrenic nerve block and to assess the effect of this on arterial carbon dioxide tension (PaCO2) in premedicated and sedated patients. Forty patients were studied, blood gases being taken on the day before surgery, immediately before performing the block and then every 20 minutes until the operation was completed. Fluoroscopy was used to determine ipsilateral hemidiaphragmatic dysfunction due to phrenic nerve block. The patients were then divided into two groups of analysis. Group A patients had evidence of phrenic nerve block, Group B patients had no evidence of phrenic nerve block. Fluoroscopy showed that 22 patients (55%) had evidence of phrenic nerve block (Group A), 18 patients showed no change (Group B). PaCO2 levels increased in both groups following premedication, from 41 +/- 5 mmHg (mean +/- SD) to 46 +/- 5 mmHg in Group A, and 41 +/- 4 mmHg in Group B; twenty minutes after cervical plexus block the PaCO2 rose to 49 +/- 6 mmHg in Group A, and 48 +/- 6 mmHg in Group B. These changes were not statistically significantly different when the two groups were compared.