The accuracy of jugular bulb venous monitoring in detecting cerebral ischemia in awake patients undergoing carotid endarterectomy

Relationships of Jugular Bulb Parameters with Cerebral Perfusion and Metabolism After Resuscitation from Cardiac Arrest: A Post-Hoc Analysis of Experimental Studies Using a Minipig Model

BACKGROUND

Cerebral blood flow (CBF) decreases in the first few hours or days following resuscitation from cardiac arrest, increasing the risk of secondary cerebral injury. Using data from experimental studies performed in minipigs, we investigated the relationships of parameters derived from arterial and jugular bulb blood gas analyses and lactate levels (jugular bulb parameters), which have been used as indicators of cerebral perfusion and metabolism, with CBF and the cerebral lactate to creatine ratio measured with dynamic susceptibility contrast magnetic resonance imaging and proton magnetic resonance spectroscopy, respectively.

METHODS

We retrospectively analyzed 36 sets of the following data obtained during the initial hours following resuscitation from cardiac arrest: percent of measured CBF relative to that at the prearrest baseline (%CBF), cerebral lactate to creatine ratio, and jugular bulb parameters, including jugular bulb oxygen saturation, jugular bulb lactate, arterial-jugular bulb oxygen content difference, cerebral extraction of oxygen, jugular bulb-arterial lactate content difference, lactate oxygen index, estimated respiratory quotient, and arterial-jugular bulb hydrogen ion content difference. Linear mixed-effects models were constructed to examine the effects of each jugular bulb parameter on the %CBF and cerebral lactate to creatine ratio.

RESULTS

The arterial-jugular bulb oxygen content difference (P = 0.047) and cerebral extraction of oxygen (P = 0.030) had a significant linear relationship with %CBF, but they explained only 12.0% (95% confidence interval [CI] 0.002-0.371) and 14.2% (95% CI 0.005-0.396) of the total %CBF variance, respectively. The arterial-jugular bulb hydrogen ion content difference had a significant linear relationship with cerebral lactate to creatine ratio (P = 0.037) but explained only 13.8% (95% CI 0.003-0.412) of the total variance in the cerebral lactate to creatine ratio. None of the other jugular bulb parameters were related to the %CBF or cerebral lactate to creatine ratio.

CONCLUSIONS

In conclusion, none of the jugular bulb parameters appeared to provide sufficient information on cerebral perfusion and metabolism in this setting.

Jugular Venous Oxygen and Lactate Parameters for Predicting Early Cognitive Dysfunction after Off-Pump Coronary Artery Bypass Grafting: A Prospective Observational Study

BACKGROUND AND OBJECTIVES

The quality of life may be negatively impacted by postoperative cognitive dysfunction (POCD) following off-pump coronary artery bypass grafting (OPCAB). It is still unclear how useful the jugular venous lactate and oxygen parameters are in predicting POCD following OPCAB.

METHODS

This prospective observational study was conducted over a period of 15 months and included 54 individuals. It sought to determine the sensitivity and specificity of jugular venous lactate and oxygen parameters for early POCD prediction in patients undergoing OPCAB. Neuropsychological tests were conducted to assess baseline cognitive function. Under ultrasound guidance, the jugular bulb was cannulated. The jugular venous lactate and oxygen parameters were measured at the time of surgery, following each graft, and 6 and 24 h later. Confusion assessment method-intensive care unit score was assessed on the third postoperative day for postoperative delirium (POD). POCD was defined as a composite Z score ≥1.96 or two Z scores in individual tests at 1 week. The jugular venous lactate and oxygen parameters of the Decline (D) group were compared to those of the Normal (N) group. Receiver operating characteristic curves were used to assess the diagnostic efficacy of derived variables.

RESULTS

The incidence of POD and POCD was 18.5% and 11.1%, respectively. At T3, all derived variables showed a significant increase, although the arterio-jugular venous lactate difference (AJDL) and modified lactate oxygen index (mLOI) were substantially greater at T3 in group D compared to group N. When predicting POCD, mLOI demonstrated the highest sensitivity at 72.22%, while AJDL showed the highest specificity at 90.7%.

CONCLUSIONS

For prediction of early POCD in patients undergoing elective OPCAB, mLOI had highest sensitivity, while AJDL had high specificity.

Cerebral and Systemic Stress Parameters in Correlation with Jugulo-Arterial CO2 Gap as a Marker of Cerebral Perfusion during Carotid Endarterectomy

Intraoperative stress is common to patients undergoing carotid endarterectomy (CEA); thus, impaired oxygen and metabolic balance may appear. In this study, we aimed to identify new markers of intraoperative cerebral ischemia, with predictive value on postoperative complications during CEA, performed in regional anesthesia. A total of 54 patients with significant carotid stenosis were recruited and submitted to CEA. Jugular and arterial blood samples were taken four times during operation, to measure the jugulo-arterial carbon dioxide partial pressure difference (P(j-a)CO₂), and cortisol, S100B, L-arginine, and lactate levels. A positive correlation was found between preoperative cortisol levels and all S100B concentrations. In addition, they are positively correlated with P(j-a)CO₂ values. Conversely, postoperative cortisol inversely correlates with P(j-a)CO₂ and postoperative S100B values. A negative correlation was observed between maximum systolic and pulse pressures and P(j-a)CO₂ after carotid clamp and before the release of clamp. Our data suggest that preoperative cortisol, S100B, L-arginine reflect patients' frailty, while these parameters postoperatively are influenced by intraoperative stress and injury. As a novelty, P(j-a)CO₂ might be an emerging indicator of cerebral blood flow during CEA.

Intraoperative Cerebral Monitoring During Carotid Surgery: A Narrative Review

BACKGROUND

Intra-operative neurological monitoring (IONM) during carotid endarterectomy (CEA) aims to reduce neurological morbidity of surgery.

OBJECTIVE

This narrative review analyses the role and results of different methods of IONM.

METHODS

review articles on PUBMED and Cochrane Library, by searching key words related to IONM and CEA, from 2000 up to date.

RESULTS

regional anesthesia in some centers represents the "gold standard". The most often used alternative techniques are: stump pressure, electroencephalogram, somatosensory evoked potentials, transcranical doppler ultrasound, near infrared spectroscopy and routine shunting. Every technique shows limitations. Regional anesthesia can make difficult prompt intubation when needed. Stump pressure shows a wide operative range. Electroencephalogram is unable to detect ischemia in sub-cortical regions of the brain. Somatosensory evoked potentials certainly demonstrate the presence of cerebral ischemia, but are no more specific or sensitive than the electroencephalogram. Transcranical doppler monitoring is undoubtedly operator-dependent and suffers from the limitations that the probe has to be placed relatively near to the surgical site and may impede the operator, especially if it needs constant adjustments; moreover, an acoustic window may not be found in 10% -20% of the subjects. Near infrared spectroscopy appears to have a high negative predictive value for cerebral ischemia, but has a poor positive predictive value and low specificity, because predominantly estimates venous oxygenation as this makes up about 80% of cerebral blood volume. The data on the use of Routine Shunting (RS) from RCTs are limited.

CONCLUSIONS

currently, with no clear consensus on monitoring technique, choice should be guided by local expertise and complication rates. With reflection, best practice may dictate that a standard technique is selected as suggested above and this remains the default position for individual practice. Nevertheless, current techniques for monitoring cerebral perfusion during CEA are associated with false negative and false positive resulting in inappropriate shunt insertion.

Monitoring cerebral ischemia during carotid endarterectomy and stenting

Current therapy for carotid stenosis mainly includes carotid endarterectomy and endovascular stenting, which may incur procedure-related cerebral ischemia. Several methods have been employed for monitoring cerebral ischemia during surgery, such as awake neurocognitive assessment, electroencephalography, evoked potentials, transcranial Doppler, carotid stump pressure, and near infrared spectroscopy. However, there is no consensus on the gold standard or the method that is superior to others at present. Keeping patient awake for real time neurocognitive assessment is effective and essential; however, not every surgeon adopts it. In patients under general anesthesia, cerebral ischemia monitoring has to rely on non-awake technologies. The advantageous and disadvantageous properties of each monitoring method are reviewed.

Monitoring of brain and systemic oxygenation in neurocritical care patients

Maintenance of adequate oxygenation is a mainstay of intensive care, however, recommendations on the safety, accuracy, and the potential clinical utility of invasive and non-invasive tools to monitor brain and systemic oxygenation in neurocritical care are lacking. A literature search was conducted for English language articles describing bedside brain and systemic oxygen monitoring in neurocritical care patients from 1980 to August 2013. Imaging techniques e.g., PET are not considered. A total of 281 studies were included, the majority described patients with traumatic brain injury (TBI). All tools for oxygen monitoring are safe. Parenchymal brain oxygen (PbtO2) monitoring is accurate to detect brain hypoxia, and it is recommended to titrate individual targets of cerebral perfusion pressure (CPP), ventilator parameters (PaCO2, PaO2), and transfusion, and to manage intracranial hypertension, in combination with ICP monitoring. SjvO2 is less accurate than PbtO2. Given limited data, NIRS is not recommended at present for adult patients who require neurocritical care. Systemic monitoring of oxygen (PaO2, SaO2, SpO2) and CO2 (PaCO2, end-tidal CO2) is recommended in patients who require neurocritical care.

Cognitive function and oxidative stress after carotid endarterectomy: comparison of propofol to sevoflurane anesthesia

OBJECTIVE

To examine the antioxidant role of propofol in ischemia-reperfusion during carotid endarterectomy (CEA) and its influence on cognitive dysfunction after CEA.

DESIGN

A randomized prospective study.

SETTING

Single-center study in a university hospital.

PARTICIPANTS

Forty-four patients.

INTERVENTIONS

Patients underwent elective CEA under general anesthesia with either sevoflurane (group S, n = 21) or propofol (group P, n = 23).

MEASUREMENTS AND MAIN RESULTS

Cognitive function was assessed with the Mini-Mental State Examination (MMSE) before CEA, 1 hour after CEA, and 24 hours after CEA. Blood samples from the radial artery and the internal jugular vein were drawn before carotid clamping and 5 minutes following unclamping, and peripheral blood was obtained 24 hours postoperatively. Samples were analyzed for lactate, S100B, and P-selectin concentrations and for the antioxidative markers malondialdehyde/low-density lipoprotein ratio and nitrate + nitrite concentrations. Compared with group S, patients in group P exhibited a greater increase in their MMSE values 24 hours postoperatively. Patients who had their MMSE performance reduced at 24 hours also were significantly fewer in group P (13% v 43% in group S, p<0.05). Significantly lower levels of lactate and S100B were observed in arterial and jugular vein samples in group P. In addition, the jugular vein-arterial differences of malondialdehyde-to-low-density lipoprotein ratio and nitrates + nitrites concentrations were lower during propofol anesthesia.

CONCLUSIONS

Propofol seemed to improve cognitive performance after CEA. This improvement was associated with decreased indices of ischemic cerebral damage and seemed to be due to antioxidative effect in the ischemic cerebral circulation.

Therapeutic hypothermia after cardiac arrest - cerebral perfusion and metabolism during upper and lower threshold normocapnia

BACKGROUND

During cardiac arrest and after successful resuscitation a continuum of ischaemia-reperfusion injury develops. Mild hypothermia exerts protective effects in the postresuscitation phase but also alters CO₂ production and solubility, which may lead to deleterious effects if overlooked when adjusting the ventilation of the resuscitated patient. Using a multimodality approach, the effects of different carbaemic states on cerebral perfusion and metabolism were evaluated during therapeutic hypothermia.

METHODS

Eight comatose survivors of prehospital cardiac arrest were cooled to 33°C for 24 h and underwent a 60 min phase of interventional lower threshold normocapnia according to temperature non-corrected pCO₂ (4.2 kPa) and higher threshold normocapnia according to corrected pCO₂ (6.0 kPa) in a random order. Prior to, during and after each phase, cerebral perfusion and metabolites via a microdialysis catheter were measured.

RESULTS

During upper-threshold pCO₂, an increase in middle cerebral artery mean flow velocity (MFV) and jugular bulb oxygen saturation (jSvO₂) were observed with a concomitant decrease in cerebral lactate concentration. Lower threshold normocapnia was associated with a decrease in MFV in most patients. In all patients jSvO₂ decreased but no change in cerebral lactate was observed. In seven patients jSvO₂ decreased below 55%. These changes were not reflected to intracranial pressure or cerebral oximetry.

CONCLUSIONS

During induced hypothermia, lower threshold normocapnia was associated with decreased cerebral perfusion/oxygenation but not reflected to interstitial metabolites. Upper threshold pCO₂ increased cerebral perfusion and reduced cerebral lactate. Vigilance over the ventilatory and CO₂ analysis regimen is mandatory during mild hypothermia.

[Anesthesia for carotid endarterectomy: a review]

Cardiovascular diseases are associated with high rates of morbidity and mortality. Carotid artery stenosis causes between 20% and 25% of ischemic strokes, especially when an embolism is the underlying cause. Carotid endarterectomy is the treatment of choice when stenosis exceeds 60%. It is important to have an understanding of how to manage perioperative factors that can decrease the risk of stroke, infarction, and death. In contrast to the findings of earlier meta-analyses, the recent GALA trial of general versus local anesthesia concluded that the rates of stroke, myocardial infarction, and mortality during or soon after surgery are similar for both types of anesthesia.

Differential influence of arterial blood glucose on cerebral metabolism following severe traumatic brain injury

INTRODUCTION

Maintaining arterial blood glucose within tight limits is beneficial in critically ill patients. Upper and lower limits of detrimental blood glucose levels must be determined.

METHODS

In 69 patients with severe traumatic brain injury (TBI), cerebral metabolism was monitored by assessing changes in arterial and jugular venous blood at normocarbia (partial arterial pressure of carbon dioxide (paCO2) 4.4 to 5.6 kPa), normoxia (partial arterial pressure of oxygen (paO2) 9 to 20 kPa), stable haematocrit (27 to 36%), brain temperature 35 to 38 degrees C, and cerebral perfusion pressure (CPP) 70 to 90 mmHg. This resulted in a total of 43,896 values for glucose uptake, lactate release, oxygen extraction ratio (OER), carbon dioxide (CO2) and bicarbonate (HCO3) production, jugular venous oxygen saturation (SjvO2), oxygen-glucose index (OGI), lactate-glucose index (LGI) and lactate-oxygen index (LOI). Arterial blood glucose concentration-dependent influence was determined retrospectively by assessing changes in these parameters within pre-defined blood glucose clusters, ranging from less than 4 to more than 9 mmol/l.

RESULTS

Arterial blood glucose significantly influenced signs of cerebral metabolism reflected by increased cerebral glucose uptake, decreased cerebral lactate production, reduced oxygen consumption, negative LGI and decreased cerebral CO2/HCO3 production at arterial blood glucose levels above 6 to 7 mmol/l compared with lower arterial blood glucose concentrations. At blood glucose levels more than 8 mmol/l signs of increased anaerobic glycolysis (OGI less than 6) supervened.

CONCLUSIONS

Maintaining arterial blood glucose levels between 6 and 8 mmol/l appears superior compared with lower and higher blood glucose concentrations in terms of stabilised cerebral metabolism. It appears that arterial blood glucose values below 6 and above 8 mmol/l should be avoided. Prospective analysis is required to determine the optimal arterial blood glucose target in patients suffering from severe TBI.