Targeted high mean arterial pressure aggravates cerebral hemodynamics after extracorporeal resuscitation in swine

Background Extracorporeal cardiopulmonary resuscitation (E-CPR) is used for the treatment of refractory cardiac arrest. However, the optimal target to reach for mean arterial pressure (MAP) remains to be determined. We hypothesized that MAP levels critically modify cerebral hemodynamics during E-CPR and tested two distinct targets (65–75 vs 80–90 mmHg) in a porcine model. Methods Pigs were submitted to 15 min of untreated ventricular fibrillation followed by 30 min of E-CPR. Defibrillations were then delivered until return of spontaneous circulation (ROSC). Extracorporeal circulation was initially set to an average flow of 40 ml/kg/min. The dose of epinephrine was set to reach a standard or a high MAP target level (65–75 vs 80–90 mmHg, respectively). Animals were followed during 120-min after ROSC. Results Six animals were included in both groups. During E-CPR, high MAP improved carotid blood flow as compared to standard MAP. After ROSC, this was conversely decreased in high versus standard MAP, while intra-cranial pressure was superior. The pressure reactivity index (PRx), which is the correlation coefficient between arterial blood pressure and intracranial pressure, also demonstrated inverted patterns of alteration according to MAP levels during E-CPR and after ROSC. In standard-MAP, PRx was transiently positive during E-CPR before returning to negative values after ROSC, demonstrating a reversible alteration of cerebral autoregulation during E-CPR. In high-MAP, PRx was negative during E-CPR but became sustainably positive after ROSC, demonstrating a prolonged alteration in cerebral autoregulation after ROSC. It was associated with a significant decrease in cerebral oxygen consumption in high- versus standard-MAP after ROSC. Conclusions During early E-CPR, MAP target above 80 mmHg is associated with higher carotid blood flow and improved cerebral autoregulation. This pattern is inverted after ROSC with a better hemodynamic status with standard versus high-MAP.

Prognostic value of baseline carotid blood flow in critically ill children with septic shock

Background and aim Hemodynamic monitoring and cardiac output (CO) assessment in the ICU have been trending toward less invasive methods. Carotid blood flow (CBF) was suggested as a candidate for CO assessment. The present study aimed to test the value of carotid artery ultrasound analysis in prediction of mortality in pediatric patients with septic shock. Methodology/Principal finding Forty children with septic shock were included in the study. Upon admission, patients were subjected to careful history taking and thorough clinical examination. The consciousness level was assessed by the Glasgow Coma Scale (GCS). Laboratory assessment included complete blood count, C-reactive protein, arterial blood gases, serum electrolytes, and liver and kidney function tests. Electrical cardiometry was used to evaluate hemodynamic parameters. Patients were also subjected to transthoracic 2-D echocardiography. CBF was evaluated using GE Vivid S5 ultrasound device through dedicated software. At the end of study, 14 patients (35.0%) died. It was found that survivors had significantly higher CBF when compared non-survivors [median (IQR): 166.0 (150.0–187.3) versus 141.0 (112.8–174.3), p = 0.033]. In addition, it was noted that survivors had longer ICU stay when compared with non-survivors [16.5 (9.8–31.5) versus 6.5 (3.0–19.5) days, p = 0.005]. ROC curve analysis showed that CBF could significantly distinguish survivors from non-survivors [AUC (95% CI): 0.3 (0.11–0.48), p = 0.035] (Fig 2). Univariate logistic regression analysis identified type of shock [OR (95% CI): 28.1 (4.9–162.4), p<0.001], CI [OR (95% CI): 0.6 (0.43–0.84), p = 0.003] and CBF [OR (95% CI): 0.98 (0.96–0.99), p = 0.031]. However, in multivariate analysis, only type of shock significantly predicted mortality. Conclusions CBF assessment may be a useful prognostic marker in children with septic shock.

EEG-Based Prediction of the Recovery of Carotid Blood Flow during Cardiopulmonary Resuscitation in a Swine Model

The recovery of cerebral circulation during cardiopulmonary resuscitation (CPR) is important to improve the neurologic outcomes of cardiac arrest patients. To evaluate the feasibility of an electroencephalogram (EEG)-based prediction model as a CPR feedback indicator of high- or low-CBF carotid blood flow (CBF), the frontal EEG and hemodynamic data including CBF were measured during animal experiments with a ventricular fibrillation (VF) swine model. The most significant 10 EEG parameters in the time, frequency and entropy domains were determined by neighborhood component analysis and Student’s t-test for discriminating high- or low-CBF recovery with a division criterion of 30%. As a binary CBF classifier, the performances of logistic regression, support vector machine (SVM), k-nearest neighbor, random forest and multilayer perceptron algorithms were compared with eight-fold cross-validation. The three-order polynomial kernel-based SVM model showed the best accuracy of 0.853. The sensitivity, specificity, F1 score and area under the curve of the SVM model were 0.807, 0.906, 0.853 and 0.909, respectively. An automated CBF classifier derived from non-invasive EEG is feasible as a potential indicator of the CBF recovery during CPR in a VF swine model.

Impact of Systemic Arterial Pressure, Collateral Vascular Resistance and Degree of Carotid Stenosis on Cerebral Blood Flow, Reserve Blood Flow, Critical Carotid Stenosis, Cerebral Ischemia and Carotid Hemodynamics

IntroductionCarotid artery stenosis related stroke is a major health care concern. Current risk management strategies for patients with asymptomatic carotid stenosis include ultrasound surveillance and occasionally an estimate of cerebral blood flow reserve. Other patient specific hemodynamic variables may be predictive of ischemic stroke risk. This study, based on a cerebral blood flow hemodynamic model, aims to investigate the impact of systemic arterial pressure, collateral vascular resistance and degree of carotid stenosis on cerebral ischemic risk, cerebrovascular blood flow reserve, critical carotid artery stenosis, carotid artery blood flow and carotid stenosis hemodynamics.MethodsThis study uses a three-component (carotid, collateral, brain) energy conservation cerebrovascular fluid mechanics model in combination with the Lassen cerebral blood flow autoregulation model that predicts cerebral blood flow in patients with carotid stenosis. It is a two-phase model, zone A when regional cerebral blood flow is autoregulated at normal values and zone B when cerebral blood flow is below normal and dependent on collateral perfusion pressure. The model solution with carotid artery occlusion defines collateral vascular resistance, with patient specific values calculated from clinical pressure measurements. In addition to cerebral blood flow the model predicts critical stenosis values and carotid and collateral blood flows as a function of systemic arterial pressure and percent diameter stenosis. Carotid stenosis blood flow velocities and energy dissipation are predicted from carotid blood flow solutions.ResultsThe model defines patient specific collateral vascular resistance, cerebral vascular resistance and critical carotid stenosis. It predicts carotid vascular resistance to be non-linearly proportional to area carotid stenosis. Solutions include reserve cerebral blood flow, the carotid and collateral components of cerebral blood flow, criteria for cerebral ischemia and carotid stenosis hemodynamics. Critical carotid stenosis is determined by mean systemic arterial pressure and the Lassen autoregulation threshold cerebral perfusion pressure. Critical stenosis values range from 61% to 76% diameter stenosis when mean systemic arterial pressures are 80mmHg to 120mmHg and the cerebral autoregulation pressure threshold is 50mmHg. When carotid stenosis is less than critical, cerebral blood flow is maintained normal and the ratios of carotid blood flow to collateral blood flow are inversely proportional to the carotid to collateral vascular resistance ratios. At stenosis greater than the critical, carotid blood flow is not adequate to maintain normal cerebral blood flow, cerebral blood flow is primarily collateral flow, all reserve blood flow is collateral and prevention of cerebral ischemia requires adequate collateral flow. Patient specific collateral vascular resistance values less than 1.0 predict normal cerebral blood flow at moderate to severe stenosis. Values greater than 1.0 predicts cerebral ischemia to be dependent on the magnitude of collateral vascular resistance. Systemic arterial pressure is a major determinant of carotid stenosis hemodynamics. Carotid blood flow velocities increase with carotid stenosis and have progressively higher variance depending on collateral blood flow as predicted by collateral vascular resistance. Turbulent flow energy dissipation intensity is similarly inversely proportional to collateral vascular resistance at severe carotid stenosis.ConclusionsCerebral, collateral and carotid blood flow solutions are determined by systemic arterial pressure, collateral vascular resistance and degree of stenosis. Critical carotid stenosis, systemic arterial pressure and collateral vascular resistance are primary determinants of cerebral ischemic risk in patients with significant carotid stenosis.

Effects of varying chest compression depths on carotid blood flow and blood pressure in asphyxiated piglets

BackgroundCurrent neonatal resuscitation guidelines recommend chest compressions (CCs) should be delivered to a depth of approximately 1/3 of the anterior–posterior (AP) chest diameter. The aim of the study was to investigate the haemodynamic effects of different CC depths in a neonatal piglet model.MethodsCCs were performed with an automated CC machine with 33%, 40% and 25% AP chest diameter in all piglets in the same order for a duration of 3 min each.ResultsEight newborn piglets (age 1–3 days, weight 1.7–2.3 kg) were included in the study. Carotid blood flow (CBF) and systolic blood pressure were the highest using a CC depth of 40% AP chest diameter (19.3±7.5 mL/min/kg and 58±32 mm Hg).ConclusionCC depth influences haemodynamic parameters in asphyxiated newborn piglets during cardiopulmonary resuscitation. The highest CBF and systolic blood pressure were achieved using a CC depth of 40% AP chest diameter.Trial registration numberPCTE0000148.

The Relationship between Carotid Doppler Ultrasound and EEG Metrics in Healthy Preschoolers and Adults

Despite widespread using electroencephalography (EEG) and Doppler ultrasound in pediatric neurology clinical practice, there are still no well-known correlations between these methods that could contribute to a better understanding of brain processes and development of neurological pathology. This study aims to reveal relationship between EEG and Doppler ultrasound methods. We compared two cohorts of adults and preschool children with no history of neurological or mental diseases. The data analysis included investigation of EEG and carotid blood flow indexes, which are significant in neurological diagnosis, as well as calculation of linear and non-linear EEG parameters and ratios between the systolic peak velocities of carotid arteries and carotid blood asymmetry. We have found age-dependent correlations between EEG and power Doppler ultrasound imaging (PDUI) data. Carotid blood flow asymmetry correlated with delta-rhythm power spectral density only in preschoolers. The ratios of blood flow velocities in the internal carotid arteries to those in the common carotid arteries correlated with higher peak alpha frequency and lower fractal dimension; moreover, they were associated with lower Epworth sleepiness scale scores. The study revealed significant correlations between EEG and PDUI imaging indexes, which are different for healthy children and adults. Despite the fact that the correlations were associated with non-clinical states such as overwork or stress, we assumed that the investigated parameters could be applicable for clinical trials.