Validation of non-invasive arterial pressure monitoring during carotid endarterectomy.

BACKGROUND: Patients undergoing carotid endarterectomy require strict arterial blood pressure (BP) control to maintain adequate cerebral perfusion. In this study we tested whether non-invasive beat-to-beat Nexfin finger BP (BPfin) can replace invasive beat-to-beat radial artery BP (BPrad) in this setting. METHODS: In 25 consecutive patients (median age 71 yr) scheduled for carotid endarterectomy and receiving general anaesthesia, BPfin and BPrad were monitored simultaneously and ipsilaterally during the 30-min period surrounding carotid artery cross-clamping. Validation was guided by the standard set by the Association for the Advancement of Medical Instrumentation (AAMI), which considers a BP monitor adequate when bias (precision) is <5 (8) mm Hg, respectively. RESULTS: BPfin vs BPrad bias (precision) was -3.3 (10.8), 6.1 (5.7) and 3.5 (5.2) mm Hg for systolic, diastolic, and mean BP, respectively. One subject was excluded due to a poor quality BP curve. In another subject, mean BPfin overestimated mean BPrad by 13.5 mm Hg. CONCLUSION: Mean BPfin could be considered as an alternative for mean BPrad during a carotid endarterectomy, based on the AAMI criteria. In 23 of 24 patients, the use of mean BPfin would not lead to decisions to adjust mean BPrad values outside the predefined BP threshold. CLINICALTRIALSGOV: NCT01451294.

Near-infrared spectroscopy to indicate selective shunt use during carotid endarterectomy.

OBJECTIVES: This study assessed the value of cerebral near-infrared spectroscopy (NIRS) and transcranial Doppler (TCD) in relation to electroencephalography (EEG) changes for the detection of cerebral hypoperfusion necessitating shunt placement during carotid endarterectomy (CEA). METHODS: This was a prospective cohort study. Patients with a sufficient TCD window undergoing CEA from February 2009 to June 2011 were included. All patients were continuously monitored with NIRS and EEG. An intraluminal shunt was placed, selectively determined by predefined EEG changes in alpha, beta, theta, or delta activity. Relative changes in regional cerebral oxygen saturation (rSO2) in the frontal lobe and mean blood flow velocity (Vmean) 30 seconds before carotid cross-clamping versus 2 minutes after carotid cross-clamping were related to shunt placement. Receiver operating characteristic curve analysis was performed to determine the optimal thresholds. Diagnostic values were reported as positive and negative predictive value (PPV and NPV). RESULTS: Of a cohort of 151 patients, 17(11%) showed EEG changes requiring shunt placement. The rSO2 and Vmean decreased more in the shunt group than in the non-shunt group (mean ± standard error of the mean) 21 ± 4% versus 7 ± 5% and 76 ± 6% versus 12 ± 3%, respectively (p < .005), Receiver operating characteristic curve analysis revealed a threshold of 16% decrease in rSO2 (PPV 76% and NPV 99%) and 48% decrease in Vmean (PPV 53% and NPV 99%) as the optimal cut-off value to detect cerebral ischemia during CEA under general anesthesia. CONCLUSIONS: Compared with EEG, we found moderate PPV but high NPV for NIRS and TCD to detect cerebral ischemia during CEA under general anesthesia, meaning that both techniques independently may be suitable to exclude patients for unnecessary shunt use and to direct the use of selective shunting. However, the optimal thresholds for NIRS remain to be determined.

Incompleteness of the circle of Willis is related to EEG-based shunting during carotid endarterectomy.

OBJECTIVES: The occurrence of cerebral ischemia during carotid endarterectomy (CEA) can be prevented by (selective) placement of an intraluminal shunt during cross-clamping. We set out to develop a rule to predict the likelihood for shunting during CEA based on preoperative assessment of collateral cerebral circulation and patient characteristics. METHODS: Patients who underwent CEA between 2004 and 2010 were included. Patients without preoperative magnetic resonance (MRA) or computed tomography angiography (CTA) were excluded. The primary endpoint was intraluminal shunt placement based on electroencephalography changes. Age, sex, cardiovascular risk factors peripheral artery disease, symptomatic status, degree of ipsilateral and contralateral carotid, status of the vertebral arteries, and morphology of the CoW were studied as potential predictors for shunt use. A prediction model was derived from a multivariable regression model using discrimination, calibration, and bootstrapping approaches and transformed into a clinical prediction model. RESULTS: A total of 431 patients were included, of which 65 patients (15%) received an intraluminal shunt. In the MRA group (n = 285) factors related to shunt use in multivariate analysis were ipsilateral carotid stenosis 90-99% (odds ratio [OR] 0.15, 95% CI 0.04-0.53), contralateral carotid occlusion (OR 4.29, 95% CI 1.68-10.95) and any not-visible anterior (OR 4.96, 95% CI 1.95-12.58) or ipsilateral posterior segment of the CoW (OR 5.08, 95% CI 2.10-12.32). In the CT group none of the factors were independently related to shunt use; therefore, only predictors describing morphology of CoW derived from MRA findings were included in our model. The c-statistic of this model was 0.79 (95% CI 0.72-0.86). Among patients with an estimated chance of needing a shunt of under 10% (49% of the population), the likelihood of shunting was 5%. In those in whom this chance was estimated higher than 30% (13% of the population) the likelihood was 51%. CONCLUSIONS: Among patients scheduled for CEA, assessment of cerebral arteries and of the configuration of the CoW based on MRA-derived images can help to identify patients with low and high likelihood of the need of shunt use during surgery.

Comparison of surgical outcomes of Carlevale sutureless scleral fixation and Artisan Aphakia intraocular lens.

PURPOSE: To compare intra- and postoperative results of sutureless scleral fixated Carlevale intraocular lens (IOL) with iris fixated Artisan IOL. METHODS: Monocentre, retrospective analysis of refractive outcomes and intra- and postoperative complications of patients who received a Carlevale or Artisan IOL between January 2019 and March 2022. RESULTS: 178 eyes of 169 patients were included (101 Carlevale and 77 Artisan IOLs). The standard follow-up time was 1 month. Two statistically significant differences were found: in the deviation of the postoperative spherical equivalent of the refraction from the preoperative chosen IOL target (p = 0.019; mean deviation was -0.46 in the Carlevale and 0.08 in the Artisan group), and the number of eyes with complications between the Carlevale and Artisan groups (p = 0.003; 33 in the Carlevale and 42 in the Artisan group). CONCLUSION: The current study is the largest so far comparing both refractive outcomes and complications after implantation of Carlevale and Artisan IOL. The Carlevale IOL does not carry a greater complication risk on the short-term follow-up. This provides additional evidence that the Carlevale IOL has to be added to the armamentarium of the ophthalmic surgeon.

Near-infrared spectroscopy can predict the onset of cerebral hyperperfusion syndrome after carotid endarterectomy.

BACKGROUND: Cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy (CEA) is a potential life-threatening complication. Therefore, early identification and treatment of patients at risk is essential. CHS can be predicted by a doubling of postoperative transcranial Doppler (TCD)-derived mean middle cerebral artery blood velocity (V(mean)) compared to preoperative values. However, in approximately 15% of CEA patients, an adequate TCD signal cannot be obtained due to an insufficient temporal bone window. Moreover, the use of TCD requires specifically skilled personnel. An alternative and promising technique of noninvasive cerebral monitoring is relative frontal lobe oxygenation (rSO(2)) measured by near-infrared spectroscopy (NIRS), which offers on-line information about cerebral oxygenation without the need for specialized personnel. In this study, we assess whether NIRS and perioperative TCD are related to the onset CHS following CEA. METHODS: Patients who underwent CEA under general anesthesia and had a sufficient TCD window were prospectively included. The V(mean) and rSO(2) measured before induction of anesthesia were compared to measurements performed in the first postoperative hour (ΔV(mean), ΔrSO(2), respectively). Logistic regression analysis was performed to determine the relationship between ΔV and ΔrSO(2) and the occurrence of CHS. Subsequently, receiver operating characteristic (ROC) curve analysis was used to determine the optimal cutoff values. Diagnostic values were shown as positive and negative predictive values (PPV and NPV). RESULTS: In total, 151 patients were included, of which 7 patients developed CHS. The ΔV(mean) and ΔrSO(2) differed between CHS and non-CHS patients (median, interquartile range), i.e. 74% (67-103) versus 16% (-2 to 41), p = 0.001, and 7% (4-15) versus 1% (-6 to 7), p = 0.009, respectively. The mean arterial blood pressure did not change. Postoperative ΔV(mean) and ΔrSO(2) were significantly related to the occurrence of CHS [odds ratio (OR) 1.40 (95% CI 1.02-1.93) per 30% increase in V(mean) and OR 1.82 (95% CI 1.11-2.99) per 5% increase in rSO(2)]. ROC curve analysis showed an area under the curve of 0.88 (p = 0.001) for ΔV(mean) and an optimal cutoff value of 67% increase (PPV 38% and NPV 99%), and an area under the curve of 0.79 (p = 0.009) for ΔrSO(2) and an optimal cutoff value of 3% rSO(2) increase (PPV 11% and NPV 100%). The combination of both monitoring techniques provided a PPV of 58% and an NPV of 99%. CONCLUSIONS: Both TCD and NIRS measurements can be used to safely identify patients not at risk of developing CHS. It appears that NIRS is a good alternative when a TCD signal cannot be obtained.

Prediction of cerebral hyperperfusion after carotid endarterectomy with transcranial Doppler.

OBJECTIVES: To determine the diagnostic value for predicting cerebral hyperperfusion syndrome (CHS) by adding a transcranial Doppler (TCD) measurement in the early postoperative phase after carotid endarterectomy (CEA). DESIGN: Patients who underwent carotid endarterectomy between January 2004 and August 2010 and in whom both intra- and postoperative TCD monitoring were performed were included. METHODS: In 184 CEA patients the mean velocity (V(mean)) preoperatively (V1), pre-clamping (V2), post-declamping (V3) and postoperatively (V4) was measured using TCD. The intra-operative V(mean) increase ((V3 - V2)/V2) was compared to the postoperative increase ((V4 - V1)/V1) in relation to CHS. CHS was diagnosed if the patient developed neurological complaints in the presence of a preoperative V(mean) increase >100%. RESULTS: Sixteen patients (9%) had an intra-operative V(mean) increase >100% and 22 patients (12%) a postoperative V(mean) increase of >100%. In 10 patients (5%) CHS was diagnosed; two of those had an intra-operative V(mean) increase of >100% and nine postoperative V(mean) increase >100%. This results in a positive predictive value of 13% for the intra-operative and 41% for the postoperative measurement. CONCLUSIONS: Besides the commonly used intra-operative TCD monitoring additional TCD measurement in the early postoperative phase is useful to more accurately predict CHS after CEA.

The value of near-infrared spectroscopy measured cerebral oximetry during carotid endarterectomy in perioperative stroke prevention. A review.

BACKGROUND: Transcranial Doppler (TCD) for identification of patients at risk for cerebral hyperperfusion syndrome (CHS) following carotid endarterectomy (CEA) cannot be performed in 10-15% of patients because of the absence of a temporal bone window. Near-infrared spectroscopy (NIRS) may be of additional value in these patients. We aimed to (1) compare the value of NIRS related to existing cerebral monitoring techniques in prediction of perioperative cerebral ischaemia and (2) compare the relation between NIRS and the occurrence of CHS. METHODS: A systematic literature search relating to NIRS and CEA was conducted in PubMed and EMBASE databases. Those included were: (1) prospective studies; (2) on NIRS for brain monitoring during CEA; (3) including comparison of NIRS to any other intra-operative cerebral monitoring systems; and (4) on either symptomatic or asymptomatic patients. RESULTS: We identified 16 studies, of which 14 focussed on the prediction of intra-operative cerebral ischaemia and shunt indication. Only two studies discussed the ability of NIRS in predicting CHS. NIRS values correlated well with TCD and electroencephalography (EEG) values indicating ischaemia. However, a threshold for postoperative cerebral ischaemia could not be determined. Neither could a threshold for selective shunting be determined since shunting criteria varied considerably across studies. The evidence suggesting that NIRS is useful in predicting CHS is modest. CONCLUSION: NIRS seems a promising monitoring technique in patients undergoing CEA. Yet the evidence to define clear cut-off points for the presence of perioperative cerebral ischaemia or identification of patients at high risk of CHS is limited. A large prospective cohort study addressing these issues is urgently needed.

Effect of bilateral carotid occlusion on cerebral hemodynamics and perivascular innervation: An experimental rat model.

We aimed to investigate the effect of chronic cerebral hypoperfusion on cerebral hemodynamics and perivascular nerve density in a rat model. Bilateral common carotid artery (CCA) ligation (n = 24) or sham-operation (n = 24) was performed with a 1-week interval. A subgroup (ligated n = 6; sham-operated n = 3) underwent magnetic resonance imaging (MRI) before the procedures and 2 and 4 weeks after the second procedure. After termination, carotids were harvested for assessment of complete ligation and nerve density in cerebral arteries that were stained for the general neural marker PGP 9.5 and sympathetic marker TH by computerized image analysis. Five rats were excluded because of incomplete ligation. MRI-based tortuosity of the posterior communicating artery (Pcom), first part of the posterior cerebral artery (P1) and basilar artery was observed in the ligated group, as well as an increased volume (p = 0.05) and relative signal intensity in the basilar artery (p = 0.04; sham-group unchanged). Immunohistochemical analysis revealed that compared to sham-operated rats, ligated rats had increased diameters of all intracircular segments and the extracircular part of the internal carotid artery (p < 0.05). Ligated rats showed a higher general nerve density compared to controls in P1 (10%, IQR:8.7-10.5 vs. 6.6%, IQR:5.5-7.4, p = 0.003) and Pcom segments (6.4%, IQR:5.8-6.5 vs. 3.2%, IQR:2.4-4.3, p = 0.003) and higher sympathetic nerve density in Pcom segments (3.7%, IQR:2.8-4.8 vs. 1.7%, IQR:1.3-2.2, p = 0.02). Bilateral CCA occlusion resulted in redistribution of blood flow to posteriorly located cerebral arteries with remarkable changes in morphology and perivascular nerve density, suggesting a functional role for perivascular nerves in cerebral autoregulation.

Role of transcranial Doppler in cerebral hyperperfusion syndrome.

The benefit of carotid revascularization is hampered by occurrence of periprocedural cerebrovascular complications. Cerebral hyperperfusion syndrome (CHS) is a potentially life threatening complication occurring in approximately 3% of all patients following either carotid endarterectomy (CEA) or carotid angioplasty with stenting (CAS). CHS generally is defined as a transcranial Doppler (TCD) derived increase in cerebral blood flow of >100% over baseline. To reduce related morbidity and mortality early identification of patients at risk is essential. As such, TCD offers a technique for cerebral blood flow measurement that is nowadays the only applied and useful clinical monitoring tool for CHS prediction. Several studies have assessed the diagnostic value of TCD in the prediction of CHS and found promising results. However, results were based on a small number of cases and different definitions have been used to diagnose CHS. Moreover, the role of TCD in the onset of CHS has been studied most extensively following CEA, and it is unclear whether the findings of these studies can be generalized to patients undergoing CAS. Therefore we conclude that further studies in larger cohorts are required to assess the changes in cerebral hemodynamic in patients undergoing either CAS or CEA.