Blood Pressure and the Brain

Postoperative stroke in acute type A aortic dissection: incidence, outcomes, and perioperative risk factors

BACKGROUND

Despite advances in surgical techniques, the incidence of stroke following acute type A aortic dissection (ATAAD) repair remains markedly high, with substantial immediate and long-term adverse outcomes such as elevated mortality, extended hospital stays, and persistent neurological impairments. The complexity of managing ATAAD extends beyond the operation itself, highlighting a crucial gap in research concerning modifiable preoperative patient conditions and perioperative anesthetic management strategies.

OBJECTIVES

This investigation aimed to elucidate the incidence, consequences, and perioperative determinants of stroke following surgical intervention for acute type A aortic dissection (ATAAD).

METHODS

In a multicenter retrospective analysis, 516 ATAAD surgery patients were evaluated. The data included demographic information, clinical profiles, surgical modalities, and outcomes. The primary endpoint was postoperative stroke incidence, with hospital mortality and other complications serving as secondary endpoints.

RESULTS

Postoperative stroke occurred in 13.6% of patients (70 out of 516) and was associated with significant extension of the ICU (median 10 vs. 5 days, P < 0.001) and hospital stay (median 18 vs. 12 days, P < 0.001). The following key independent stroke risk factors were identified: modified Frailty Index (mFI) ≥ 4 (odds ratio [OR]: 4.18, 95% confidence interval [CI]: 1.24-14.1, P = 0.021), common carotid artery malperfusion (OR: 3.76, 95% CI: 1.23-11.44, P = 0.02), pre-cardiopulmonary bypass (CPB) hypotension (mean arterial pressure ≤ 50 mmHg; OR: 2.17, 95% CI: 1.06-4.44, P = 0.035), ≥ 20% intraoperative decrease in cerebral regional oxygen saturation (rSO2) (OR: 1.93, 95% CI: 1.02-3.64, P = 0.042), and post-CPB vasoactive-inotropic score (VIS) ≥ 10 (OR: 2.24, 95% CI: 1.21-4.14, P = 0.01).

CONCLUSIONS

Postoperative stroke significantly increases ICU and hospital durations in ATAAD surgery patients. These findings highlight the critical need to identify and mitigate major risks, such as high mFI, common carotid artery malperfusion, pre-CPB hypotension, significant cerebral rSO2 reductions, and elevated post-CPB VIS, to improve outcomes and reduce stroke prevalence.

TRIAL REGISTRATION

Thai Clinical Trials Registry (TCTR20230615002). Date registered on June 15, 2023. Retrospectively registered.

Cerebral autoregulation derived blood pressure targets in elective neurosurgery

Poor postoperative outcomes may be associated with cerebral ischaemia or hyperaemia, caused by episodes of arterial blood pressure (ABP) being outside the range of cerebral autoregulation (CA). Monitoring CA using COx (correlation between slow changes in mean ABP and regional cerebral O2 saturation-rSO2) could allow to individualise the management of ABP to preserve CA. We aimed to explore a continuous automated assessment of ABPOPT (ABP where CA is best preserved) and ABP at the lower limit of autoregulation (LLA) in elective neurosurgery patients. Retrospective analysis of prospectively collected data of 85 patients [median age 60 (IQR 51-68)] undergoing elective neurosurgery. ABPBASELINE was the mean of 3 pre-operative non-invasive measurements. ABP and rSO2 waveforms were processed to estimate COx-derived ABPOPT and LLA trend-lines. We assessed: availability (number of patients where ABPOPT/LLA were available); time required to achieve first values; differences between ABPOPT/LLA and ABP. ABPOPT and LLA availability was 86 and 89%. Median (IQR) time to achieve the first value was 97 (80-155) and 93 (78-122) min for ABPOPT and LLA respectively. Median ABPOPT [75 (69-84)] was lower than ABPBASELINE [90 (84-95)] (p < 0.001, Mann-U test). Patients spent 72 (56-86) % of recorded time with ABP above or below ABPOPT ± 5 mmHg. ABPOPT and ABP time trends and variability were not related to each other within patients. 37.6% of patients had at least 1 hypotensive insult (ABP < LLA) during the monitoring time. It seems possible to assess individualised automated ABP targets during elective neurosurgery.

Monitoring of cerebral blood flow autoregulation: physiologic basis, measurement, and clinical implications

Cerebral blood flow (CBF) autoregulation is the physiologic process whereby blood supply to the brain is kept constant over a range of cerebral perfusion pressures ensuring a constant supply of metabolic substrate. Clinical methods for monitoring CBF autoregulation were first developed for neurocritically ill patients and have been extended to surgical patients. These methods are based on measuring the relationship between cerebral perfusion pressure and surrogates of CBF or cerebral blood volume (CBV) at low frequencies (<0.05 Hz) of autoregulation using time or frequency domain analyses. Initially intracranial pressure monitoring or transcranial Doppler assessment of CBF velocity was utilised relative to changes in cerebral perfusion pressure or mean arterial pressure. A more clinically practical approach utilising filtered signals from near infrared spectroscopy monitors as an estimate of CBF has been validated. In contrast to the traditional teaching that 50 mm Hg is the autoregulation threshold, these investigations have found wide interindividual variability of the lower limit of autoregulation ranging from 40 to 90 mm Hg in adults and 20-55 mm Hg in children. Observational data have linked impaired CBF autoregulation metrics to adverse outcomes in patients with traumatic brain injury, ischaemic stroke, subarachnoid haemorrhage, intracerebral haemorrhage, and in surgical patients. CBF autoregulation monitoring has been described in both cardiac and noncardiac surgery. Data from a single-centre randomised study in adults found that targeting arterial pressure during cardiopulmonary bypass to above the lower limit of autoregulation led to a reduction of postoperative delirium and improved memory 1 month after surgery compared with usual care. Together, the growing body of evidence suggests that monitoring CBF autoregulation provides prognostic information on eventual patient outcomes and offers potential for therapeutic intervention. For surgical patients, personalised blood pressure management based on CBF autoregulation data holds promise as a strategy to improve patient neurocognitive outcomes.

Quantification of dynamic cerebral autoregulation: welcome to the jungle!

PURPOSE

Patients with dysautonomia often experience symptoms such as dizziness, syncope, blurred vision and brain fog. Dynamic cerebral autoregulation, or the ability of the cerebrovasculature to react to transient changes in arterial blood pressure, could be associated with these symptoms.

METHODS

In this narrative review, we go beyond the classical view of cerebral autoregulation to discuss dynamic cerebral autoregulation, focusing on recent advances pitfalls and future directions.

RESULTS

Following some historical background, this narrative review provides a brief overview of the concept of cerebral autoregulation, with a focus on the quantification of dynamic cerebral autoregulation. We then discuss the main protocols and analytical approaches to assess dynamic cerebral autoregulation, including recent advances and important issues which need to be tackled.

CONCLUSION

The researcher or clinician new to this field needs an adequate comprehension of the toolbox they have to adequately assess, and interpret, the complex relationship between arterial blood pressure and cerebral blood flow in healthy individuals and clinical populations, including patients with autonomic disorders.

Cerebral hemodynamics after cardiac arrest: implications for clinical management

Following resuscitation from cardiac arrest, hypoxic ischemic brain injury (HIBI) ensues, which is the primary determinant of adverse outcome. The pathophysiology of HIBI can be compartmentalized into primary and secondary injury, resulting from cerebral ischemia during cardiac arrest and reperfusion following successful resuscitation, respectively. During the secondary injury phase, increased attention has been directed towards the optimization of cerebral oxygen delivery to prevent additive injury to the brain. During this phase, cerebral hemodynamics are characterized by early hyperemia following resuscitation and then a protracted phase of cerebral hypoperfusion termed "no-reflow" during which additional hypoxic-ischemic injury can occur. As such, identification of therapeutic strategies to optimize cerebral delivery of oxygen is at the forefront of HIBI research. Unfortunately, randomized control trials investigating the manipulation of arterial carbon dioxide tension and mean arterial pressure augmentation as methods to potentially improve cerebral oxygen delivery have shown no impact on clinical outcomes. Emerging literature suggests differential patient-specific phenotypes may exist in patients with HIBI. The potential to personalize therapeutic strategies in the critical care setting based upon patient-specific pathophysiology presents an attractive strategy to improve HIBI outcomes. Herein, we review the cerebral hemodynamic pathophysiology of HIBI, discuss patient phenotypes as it pertains to personalizing care, as well as suggest future directions.

Clinical targeting of the cerebral oxygen cascade to improve brain oxygenation in patients with hypoxic-ischaemic brain injury after cardiac arrest

The cerebral oxygen cascade includes three key stages: (a) convective oxygen delivery representing the bulk flow of oxygen to the cerebral vascular bed; (b) diffusion of oxygen from the blood into brain tissue; and (c) cellular utilisation of oxygen for aerobic metabolism. All three stages may become dysfunctional after resuscitation from cardiac arrest and contribute to hypoxic-ischaemic brain injury (HIBI). Improving convective cerebral oxygen delivery by optimising cerebral blood flow has been widely investigated as a strategy to mitigate HIBI. However, clinical trials aimed at optimising convective oxygen delivery have yielded neutral results. Advances in the understanding of HIBI pathophysiology suggest that impairments in the stages of the oxygen cascade pertaining to oxygen diffusion and cellular utilisation of oxygen should also be considered in identifying therapeutic strategies for the clinical management of HIBI patients. Culprit mechanisms for these impairments may include a widening of the diffusion barrier due to peri-vascular oedema and mitochondrial dysfunction. An integrated approach encompassing both intra-parenchymal and non-invasive neuromonitoring techniques may aid in detecting pathophysiologic changes in the oxygen cascade and enable patient-specific management aimed at reducing the severity of HIBI.

Lateral position does not cause an interhemicerebral difference of cerebral hemodynamic in healthy adult volunteers

Cerebral perfusion is maintained at a consistent value irrespective of changes in systemic blood pressure or disease-induced changes in general physical condition. This regulatory mechanism is effective despite postural changes, working even during changes in posture, such as those from sitting to standing or from the head-down to the head-up position. However, no study has addressed changes in perfusion separately in the left and right cerebral hemispheres, and there has been no specific investigation of the effect of the lateral decubitus position on perfusion in each hemisphere. Surgery, particularly respiratory surgery, is often performed with the patient in the lateral decubitus position, and since intraoperative anesthesia may also have an effect, it is important to ascertain the effect of the lateral decubitus position on perfusion in the left and right cerebral hemispheres in the absence of anesthesia. The effects of the lateral decubitus position on heart rate, blood pressure, and hemodynamic in the left and right cerebral hemispheres assessed by regional saturation of oxygen measured by near-infrared spectroscopy were investigated in healthy adult volunteers. Although the lateral decubitus position causes systemic circulatory changes, it may not cause any difference in hemodynamic between the left and right cerebral hemispheres.

Carotid Doppler ultrasound for non-invasive haemodynamic monitoring: a narrative review

Objective.Accurate haemodynamic monitoring is the cornerstone in the management of critically ill patients. It guides the optimization of tissue and organ perfusion in order to prevent multiple organ failure. In the past decades, carotid Doppler ultrasound (CDU) has been explored as a non-invasive alternative for long-established invasive haemodynamic monitoring techniques. Considering the large heterogeneity in reported studies, we conducted a review of the literature to clarify the current status of CDU as a haemodynamic monitoring tool.Approach.In this article, firstly an overview is given of the equipment and workflow required to perform a CDU exam in clinical practice, the limitations and technical challenges potentially faced by the CDU sonographer, and the cerebrovascular mechanisms that may influence CDU measurement outcomes. The following chapter describes alternative techniques for non-invasive haemodynamic monitoring, detailing advantages and limitations compared to CDU. Next, a comprehensive review of the literature regarding the use of CDU for haemodynamic monitoring is presented. Furthermore, feasibility aspects, training requirements and technical developments of CDU are addressed.Main results.Based on the outcomes of these studies, we assess the applicability of CDU-derived parameters within three clinical domains (cardiac output, volume status, and fluid responsiveness), and amongst different patient groups. Finally, recommendations are provided to improve the quality and standardization of future research and clinical practice in this field.Significance.Although CDU is not yet interchangeable with invasive 'gold standard' cardiac output monitoring, the present work shows that certain CDU-derived parameters prove promising in the context of functional haemodynamic monitoring.

Steady-state cerebral blood flow and dynamic cerebral autoregulation during neck flexion and extension in seated healthy young adults

Neck flexion and extension show differences in various physiological factors, such as sympathetic nerve activity and intracranial pressure (ICP). We hypothesized that differences would exist in steady-state cerebral blood flow and dynamic cerebral autoregulation between neck flexion and extension in seated, healthy young adults. Fifteen healthy adults were studied in the sitting position. Data were collected during neck flexion and extension in random order for 6 min each on the same day. Arterial pressure at the heart level was measured using a cuff sphygmomanometer. Mean arterial pressure at the middle cerebral artery (MCA) level (MAP_MCA ) was calculated by subtracting the hydrostatic pressure difference between heart and MCA levels from mean arterial pressure at the heart level. Non-invasive cerebral perfusion pressure (nCPP) was estimated as the MAP_MCA minus the non-invasive ICP as determined from transcranial Doppler ultrasonography. Waveforms of arterial pressure in the finger and blood velocity in the MCA (MCAv) were obtained. Dynamic cerebral autoregulation was evaluated by transfer function analysis between these waveforms. The results showed that nCPP was significantly higher during neck flexion than during neck extension (p = 0.004). However, no significant differences were observed in mean MCAv (p = 0.752). Likewise, no significant differences were observed in any of the three indices of dynamic cerebral autoregulation in any frequency range. Although non-invasively estimated cerebral perfusion pressure was significantly higher during neck flexion than during neck extension, no differences in steady-state cerebral blood flow or dynamic cerebral autoregulation were evident between neck flexion and extension in seated healthy adults.

A comprehensive review of cerebral oximetry in cardiac surgery

BACKGROUND

Patients who undergo cardiac surgery are at increased risk of stroke, postoperative cognitive decline, and delirium. These neurocognitive complications have led to increased costs, intensive care unit stays, morbidity, and mortality. As a result, there is a significant push to mitigate any neurological complications in cardiac surgery patients. Near-infrared spectroscopy to measure regional cerebral oxygen saturations has gained consideration due to its noninvasive and user-friendly nature. Cerebral oximetry desaturations during cardiac surgery have been linked to an array of adverse clinical outcomes. However, the most effective intraoperative interventions to protect this vulnerable patient population have yet to be ascertained.

AIM OF STUDY

To provide a comprehensive summary of the intraoperative management for cerebral oximetry desaturations during cardiac surgery. The review highlights clinical outcomes from cerebral oximetry use to quantify the importance of identifying cerebral desaturations during cardiac surgery. The review then interrogates possible interventions for cerebral oximetry desaturations in an effort to determine which interventions are most efficacious and to enlighten possible areas for further research.

METHODS

A narrative review of randomized controlled trials, observational studies, and systematic reviews with metanalyses was performed through August 2021.

RESULTS

There is significant heterogeneity among patient populations for which cerebral oximetry monitoring has been studied in cardiac surgery. Further, the definition of a clinically significant cerebral desaturation and the assessment of neurocognitive outcomes varied substantially across studies. As a result, metanalysis is challenging and few conclusions can be drawn. Cerebral oximetry use during cardiac surgery has not been associated with improvements in neurocognitive outcomes, morbidity, or mortality to date. The evidence to support a particular intervention for an acute desaturation is equivocal.

CONCLUSIONS

Future research is needed to quantify a clinically significant cerebral desaturation and to determine which interventions for an acute desaturation effectively improve clinical outcomes.

Acute Hospital Management of Pediatric Stroke

The field of pediatric stroke has historically been hampered by limited evidence and small patient cohorts. However the landscape of childhood stroke is rapidly changing due in part to increasing awareness of the importance of pediatric stroke and the emergence of dedicated pediatric stroke centers, care pathways, and alert systems. Acute pediatric stroke management hinges on timely diagnosis confirmed by neuroimaging, appropriate consideration of recanalization therapies, implementation of neuroprotective measures, and attention to secondary prevention. Because pediatric stroke is highly heterogenous in etiology, management strategies must be individualized. Determining a child's underlying stroke etiology is essential to appropriately tailoring hyperacute stroke management and determining best approach to secondary prevention. Herein, we review the methods of recognition, diagnosis, management, current knowledge gaps and promising research for pediatric stroke.

Preoperative oral diazepam for intraoperative blood pressure stabilisation in hypertensive patients undergoing vitrectomy under retrobulbar nerve block anaesthesia: study protocol for a randomised controlled trial

Background

As a type of local anaesthesia, retrobulbar nerve block is often used in vitrectomy, with patients remaining conscious during the operation. The increase in systolic blood pressure (SBP) caused by tension and fear during the operation—especially in patients with a history of hypertension—can negatively impact the safety of the procedure, resulting in suprachoroidal haemorrhage or retinal haemorrhage. Diazepam has a sedative effect and can relieve tension during surgery. This study aims to evaluate the efficacy and safety of diazepam for intraoperative BP stabilisation in hypertensive patients under retrobulbar anaesthesia during surgery.

Methods

This single-centre, double-blind, randomised controlled and parallel clinical trial will include 180 hypertensive patients who will undergo vitrectomy with nerve block anaesthesia. Study participants will be randomly allocated in a 1:1 ratio to intervention (patients receiving oral diazepam before the operation) and control (patients receiving oral placebo before the operation) groups. The primary outcome is the effective rate of intraoperative BP control (systolic BP during operation maintained at <160mmHg at all timepoints). The secondary outcomes are the proportion of patients with SBP ≥180 mmHg at any timepoint from operation to 1 h post-operation, the change of mean systolic blood pressure and mean heart rate during operation from baseline, as well as the number of patients with intraoperative and post-operative adverse reactions within 12 weeks of surgery. The logistic regression model will be performed to compare the outcomes.

Discussion

This study will evaluate the efficacy and safety of diazepam for intraoperative BP stabilisation in hypertensive patients under nerve block anaesthesia during surgery. The results of this trial will reveal whether diazepam has a significant effect on intraoperative BP stability in patients with a history of hypertension who require vitrectomy. If the results of this trial are significant, a large-scale multi-centre clinical trial can be designed.

Trial registration

Chinese Clinical Trial Registry (ChiCTR) ChiCTR2100041772. Registered on 5 January 2021.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06686-y.

Clinical Implication of the Acumen Hypotension Prediction Index for Reducing Intraoperative Haemorrhage in Patients Undergoing Lumbar Spinal Fusion Surgery: A Prospective Randomised Controlled Single-Blinded Trial

We investigated the clinical implication of the Hypotension Prediction Index (HPI) in decreasing amount of surgical haemorrhage and requirements of blood transfusion compared to the conventional method (with vs. without HPI monitoring). A prospective, randomised controlled-trial of 19- to 73-year-old patients (n = 76) undergoing elective lumbar spinal fusion surgery was performed. According to the exclusion criteria, the patients were divided into the non-HPI (n = 33) and HPI (n = 35) groups. The targeted-induced hypotension systolic blood pressure was 80−100 mmHg (in both groups), with HPI > 85 (in the HPI group). Intraoperative bleeding was lower in the HPI group (299.3 ± 219.8 mL) than in the non-HPI group (532 ± 232.68 mL) (p = 0.001). The non-HPI group had a lower level of haemoglobin at the end of the surgery with a larger decline in levels. The incidence of postoperative transfusion of red blood cells was higher in the non-HPI group than in the HPI group (9 (27.3%) vs. 1 (2.9%)). The use of HPI monitoring may play a role in providing timely haemodynamic information that leads to improving the quality of induced hypotension care and to ameliorate intraoperative surgical blood loss and postoperative demand for blood transfusion in patients undergoing lumbar fusion surgery.

Cerebral hemodynamics during sustained intra-operative hypotension

Background Static cerebral autoregulation (CA) maintains cerebral blood flow (CBF) relatively constant above a mean arterial blood pressure (BP_mean) of 60-65 mmHg. Below this lower limit of CA (LLCA), CBF declines along with BP_mean. Data are lacking describing how CA reacts to sustained hypotension, since hypotension is usually avoided. In this study, we took advantage of a procedure requiring sustained hypotension. We assessed static CA for LLCA determination, and a more continuous CA, which counter short-term blood pressure variations. With these data, we analyzed CA during longstanding hypotension. Methods Continuous arterial blood pressure and middle cerebral artery blood flow velocity (MCAV_mean) were monitored in 23 patients that required deep intra-operative hypotension. The LLCA was determined for every patient, and BP_mean below this LLCA was classified as the patient specific hypotension. With the mean flow index (Mx_a) continuous CA (Mx_a-CA) was quantified. Mx_a was calculated and averaged after induction of general anesthesia (baseline), every 15 minutes during, and 15 minutes after one-hour of hypotension. Functioning CA was defined as Mx_a <0.4. Data are expressed as median (25^th-75^th percentile). Results The LLCA was located at 56 (47-74) mmHg. At baseline, Mx_a was 0.21 (0.14-0.32) and 0.61 (0.48-0.78) during hypotension (p<0.01), with no appreciable change over time, n=12. After blood pressure restoration, Mx_a improved, 0.25 (0.06-0.35, n=9). Conclusions Mx_a-CA became and remained disturbed during the one-hour of hypotension, and improved after blood pressure restoration. This completely reversible situation suggests no ischemic hyperemia occurs and renders an adaptation mechanism during sustained hypotension unlikely.

Effectiveness of the advisory display SmartPilot® view in the assessment of anesthetic depth in low risk gynecological surgery patients: a randomized controlled trial

Background

Assessment of appropriate anesthetic depth is crucial to prevent harm to patients. Unnecessary deep anesthesia can be harmful, potentially causing acute renal failure, myocardial injury, delirium, and an increased mortality rate. Conversely, too light anesthesia combined with muscle relaxants can result in intraoperative patient awareness and lead to serious psychological trauma. This trial aimed to ascertain the effectiveness of the advisory display SmartPilot® View (SPV), as a supplemental measure in the assessment of anesthetic depth in low risk gynecological surgery patients. The hypothesis was that the use of the SPV would increase the precision of assessment, and result in a higher mean arterial pressure.

Methods

This trial used a randomized, controlled, single-blind design with a homogeneous sample. Patients undergoing minor, low risk gynecological surgery were randomly assigned to two groups: a test group wherein current standards were supplemented with the advisory display SPV and a control group assessed using only the current standards. Female patients aged between 18 and 75 years with American Society of Anesthesiologists Physical Status Classification System scores of 1–3 undergoing planned general anesthesia using the total intravenous anesthetic method, combining propofol and remifentanil, were included. The exclusion criteria included a body mass index ≥ 35 kg/m², a history of alcoholism, drug intake affecting propofol and remifentanil dynamics, and inability to consent. The independent sample t-test and chi-square test or Fisher’s exact test were used to assess the statistical significance of differences between the two groups.

Results

A total of 114 patients were included in the analysis (test group n = 58, control group n = 56). No significant differences in the mean arterial pressure, heart rate, bispectral index, extubation delay, or post-anesthesia care unit stay were found between groups.

Conclusions

The addition of the advisory display SmartPilot® View to current standards in the evaluation of anesthetic depth had no significant effect on the outcome.

Trial registration

The trial was registered on January 16th 2019 with ClinicalTrials.gov (ref: NCT03807271).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01593-w.

Early Cognitive Dysfunction in Elderly Patients after Total Knee Arthroplasty: An Analysis of Risk Factors and Cognitive Functional Levels

Background

Cognitive dysfunction after total knee arthroplasty (TKA) is very common in elderly patients. Postoperative cognitive dysfunction (POCD), as a form of cognitive dysfunction, may affect patients' short- and long-term recoveries. The identification of meaningful risk factors may help reduce the occurrence of POCD in the future.

Objective

Our goal was to retrospectively investigate the risk factors for early POCD in elderly patients undergoing TKA and to further analyze the relationship between the intensity of risk factors and the level of cognitive function.

Methods

The related indicators and the Montreal Cognitive Function Assessment Scale (MOCA) scores of 105 elderly patients were collected by searching the electronic case system. According to the postoperative MOCA score, patients were divided into three groups: normal group (group N), mild POCD group (group M), and severe POCD group (group S). SPSS 25.0 software was used for statistical analyses.

Results

At baseline, the preoperative MOCA score was significantly different in patients with POCD (P ≤ 0.001), while other baseline indicators were not significantly different. In terms of changes in hemoglobin levels, statistically significant differences were observed between group M, group S, and group N (P = 0.039). Among inflammatory indicators, only postoperative CRP levels showed a statistically significant difference in patients with POCD (P = 0.041). Postoperative pain was also significantly different among the three groups (P = 0.009). The multivariate regression analysis revealed that a low preoperative MOCA score and severe postoperative pain were independent risk factors for mild and severe cognitive impairment, while a high postoperative CRP level was only an independent risk factor for mild cognitive impairment.

Conclusions

Our study found that the level of preoperative cognitive function, postoperative CRP level, and postoperative pain were independent risk factors for POCD. Moreover, the levels of preoperative cognitive function and postoperative pain were more strongly correlated with severe POCD than postoperative CRP levels.

Application of Controlled Hypotension During Surgery for Spinal Metastasis

With advances in tumor treatment, metastasis to bone is increasing, and surgery has become the only choice for most terminal patients. However, spinal surgery has a high risk and is prone to heavy bleeding. Controlled hypotension during surgery has outstanding advantages in reducing intraoperative bleeding and ensuring a clear field of vision, thus avoiding damage to important nerves and vessels. Antihypertensive drugs should be carefully selected after considering the patient's age, different diseases, etc, and a single or combined regimen can be used. Hypotension also inevitably leads to a decrease in perfusion of important organs, so the threshold of hypotension and the maintenance time of hypotension should be strictly limited, and the monitoring of important organs during the operation is particularly important. Information such as blood perfusion, blood oxygen saturation, cardiac output, and neurophysiological conduction potential changes should be obtained in a timely fashion, which will help to reduce the risk of hypotension. In short, when applying controlled hypotension, it is necessary to choose an appropriate threshold and duration, and appropriate monitoring should be conducted during the operation to ensure the safety of the patient.

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.

Assessment of Myocardial Function During Blood Pressure Manipulations Using Feature Tracking Cardiovascular Magnetic Resonance

Background: Coronary autoregulation is a feedback system, which maintains near-constant myocardial blood flow over a range of mean arterial pressure (MAP). Yet in emergency or peri-operative situations, hypotensive or hypertensive episodes may quickly arise. It is not yet established how rapid blood pressure changes outside of the autoregulation zone (ARZ) impact left (LV) and right ventricular (RV) function. Using cardiovascular magnetic resonance (CMR) imaging, measurements of myocardial tissue oxygenation and ventricular systolic and diastolic function can comprehensively assess the heart throughout a range of changing blood pressures.

Design and methods: In 10 anesthetized swine, MAP was varied in steps of 10–15 mmHg from 29 to 196 mmHg using phenylephrine and urapidil inside a 3-Tesla MRI scanner. At each MAP level, oxygenation-sensitive (OS) cine images along with arterial and coronary sinus blood gas samples were obtained and blood flow was measured from a surgically implanted flow probe on the left anterior descending coronary artery. Using CMR feature tracking-software, LV and RV circumferential systolic and diastolic strain parameters were measured from the myocardial oxygenation cines.

Results: LV and RV peak strain are compromised both below the lower limit (LV: Δ1.2 ± 0.4%, RV: Δ4.4 ± 1.2%, p < 0.001) and above the upper limit (LV: Δ2.1 ± 0.4, RV: Δ5.4 ± 1.4, p < 0.001) of the ARZ in comparison to a baseline of 70 mmHg. LV strain demonstrates a non-linear relationship with invasive and non-invasive measures of oxygenation. Specifically for the LV at hypotensive levels below the ARZ, systolic dysfunction is related to myocardial deoxygenation (β = −0.216, p = 0.036) in OS-CMR and both systolic and diastolic dysfunction are linked to reduced coronary blood flow (peak strain: β = −0.028, p = 0.047, early diastolic strain rate: β = 0.026, p = 0.002). These relationships were not observed at hypertensive levels.

Conclusion: In an animal model, biventricular function is compromised outside the coronary autoregulatory zone. Dysfunction at pressures below the lower limit is likely caused by insufficient blood flow and tissue deoxygenation. Conversely, hypertension-induced systolic and diastolic dysfunction points to high afterload as a cause. These findings from an experimental model are translatable to the clinical peri-operative environment in which myocardial deformation may have the potential to guide blood pressure management, in particular at varying individual autoregulation thresholds.

Intraoperative Invasive Blood Pressure Monitoring and the Potential Pitfalls of Invasively Measured Systolic Blood Pressure

Invasive intraarterial blood pressure measurement is currently the gold standard for intraoperative hemodynamic monitoring but accurate systolic blood pressure (SBP) measurement is difficult in everyday clinical practice, mostly because of problems with hyper-resonance or damping within the measurement system, which can lead to erroneous treatment decisions if these phenomena are not recognized. A hyper-resonant blood pressure trace significantly overestimates true systolic blood pressure while underestimating the diastolic pressure. Invasively measured systolic blood pressure is also significantly more affected than mean blood pressure by the site of measurement within the arterial system. Patients in the intraoperative period should be treated based on the invasively measured mean blood pressure rather than the systolic blood pressure. In this review, we discuss the pros/cons, mechanisms of invasive blood pressure measurements, and the interpretation of the invasively measured systolic blood pressure value.

Association of deranged cerebrovascular reactivity with brain injury following cardiac arrest: a post-hoc analysis of the COMACARE trial

BACKGROUND

Impaired cerebrovascular reactivity (CVR) is one feature of post cardiac arrest encephalopathy. We studied the incidence and features of CVR by near infrared spectroscopy (NIRS) and associations with outcome and biomarkers of brain injury.

METHODS

A post-hoc analysis of 120 comatose OHCA patients continuously monitored with NIRS and randomised to low- or high-normal oxygen, carbon dioxide and mean arterial blood pressure (MAP) targets for 48 h. The tissue oximetry index (TO_x) generated by the moving correlation coefficient between cerebral tissue oxygenation measured by NIRS and MAP was used as a dynamic index of CVR with TO_x > 0 indicating impaired reactivity and TO_x > 0.3 used to delineate the lower and upper MAP bounds for disrupted CVR. TO_x was analysed in the 0-12, 12-24, 24-48 h time-periods and integrated over 0-48 h. The primary outcome was the association between TO_x and six-month functional outcome dichotomised by the cerebral performance category (CPC1-2 good vs. 3-5 poor). Secondary outcomes included associations with MAP bounds for CVR and biomarkers of brain injury.

RESULTS

In 108 patients with sufficient data to calculate TO_x, 76 patients (70%) had impaired CVR and among these, chronic hypertension was more common (58% vs. 31%, p = 0.002). Integrated TO_x for 0-48 h was higher in patients with poor outcome than in patients with good outcome (0.89 95% CI [- 1.17 to 2.94] vs. - 2.71 95% CI [- 4.16 to - 1.26], p = 0.05). Patients with poor outcomes had a decreased upper MAP bound of CVR over time (p = 0.001), including the high-normal oxygen (p = 0.002), carbon dioxide (p = 0.012) and MAP (p = 0.001) groups. The MAP range of maintained CVR was narrower in all time intervals and intervention groups (p < 0.05). NfL concentrations were higher in patients with impaired CVR compared to those with intact CVR (43 IQR [15-650] vs 20 IQR [13-199] pg/ml, p = 0.042).

CONCLUSION

Impaired CVR over 48 h was more common in patients with chronic hypertension and associated with poor outcome. Decreased upper MAP bound and a narrower MAP range for maintained CVR were associated with poor outcome and more severe brain injury assessed with NfL. Trial registration ClinicalTrials.gov, NCT02698917 .

Controlled arterial hypotension during resection of cerebral arteriovenous malformations

Background

Resection of cerebral arteriovenous malformations (AVM) is technically demanding because of size, eloquent location or diffuse nidus. Controlled arterial hypotension (CAH) could facilitate haemostasis. We performed a study to characterize the duration and degree of CAH and to investigate its association with blood loss and outcome.

Methods

We retrospectively analysed intraoperative arterial blood pressure of 56 patients that underwent AVM-resection performed by the same neurosurgeon between 2003 and 2012. Degree of CAH, AVM size, grading and neurological outcome were studied. Patients were divided into two groups, depending on whether CAH was performed (hypotension group) or not (control group).

Results

The hypotension group consisted of 28 patients, which presented with riskier to treat AVMs and a higher Spetzler-Martin grading. CAH was achieved by application of urapidil, increasing anaesthetic depth or a combination thereof. Systolic and mean arterial blood pressure were lowered to 82 ± 7 and 57 ± 7 mmHg, respectively, for a median duration of 58 min [25% percentile: 26 min.; 75% percentile: 107 min]. In the hypotension group, duration of surgery (4.4 ± 1.3 h) was significantly (p <  0.001) longer, and median blood loss (500 ml) was significantly (p = 0.002) higher than in the control group (3.3 ± 0.9 h and 200 ml, respectively). No case fatalities occurred. CAH was associated with a higher amount of postoperative neurological deficits.

Conclusions

Whether CAH caused neurological deficits or prevented worse outcomes could be clarified by a prospective randomised study, which is regarded as ethically problematic in the context of bleeding. CAH should only be used after strict indication and should be applied as mild and short as possible.

Losing the dogmatic view of cerebral autoregulation

In 1959, Niels Lassen illustrated the cerebral autoregulation curve in the classic review article entitled Cerebral Blood Flow and Oxygen Consumption in Man. This concept suggested a relatively broad mean arterial pressure range (~60-150 mmHg) wherein cerebral blood flow remains constant. However, the assumption that this wide cerebral autoregulation plateau could be applied on a within-individual basis is incorrect and greatly variable between individuals. Indeed, each data point on the autoregulatory curve originated from independent samples of participants and patients and represented interindividual relationships between cerebral blood flow and mean arterial pressure. Nonetheless, this influential concept remains commonly cited and illustrated in various high-impact publications and medical textbooks, and is frequently taught in medical and science education without appropriate nuances and caveats. Herein, we provide the rationale and additional experimental data supporting the notion we need to lose this dogmatic view of cerebral autoregulation.

Cerebral Autoregulation in Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating stroke subtype with a high rate of mortality and morbidity. The poor clinical outcome can be attributed to the biphasic course of the disease: even if the patient survives the initial bleeding emergency, delayed cerebral ischemia (DCI) frequently follows within 2 weeks time and levies additional serious brain injury. Current therapeutic interventions do not specifically target the microvascular dysfunction underlying the ischemic event and as a consequence, provide only modest improvement in clinical outcome. SAH perturbs an extensive number of microvascular processes, including the “automated” control of cerebral perfusion, termed “cerebral autoregulation.” Recent evidence suggests that disrupted cerebral autoregulation is an important aspect of SAH-induced brain injury. This review presents the key clinical aspects of cerebral autoregulation and its disruption in SAH: it provides a mechanistic overview of cerebral autoregulation, describes current clinical methods for measuring autoregulation in SAH patients and reviews current and emerging therapeutic options for SAH patients. Recent advancements should fuel optimism that microvascular dysfunction and cerebral autoregulation can be rectified in SAH patients.

Effects on cerebral blood flow of position changes, hyperoxia, CO2 partial pressure variations and the Valsalva manoeuvre: A study in healthy volunteers

BACKGROUND

Maintaining adequate blood pressure to ensure proper cerebral blood flow (CBF) during surgery is challenging. Induced mild hypotension, sitting position or unavoidable intra-operative circumstances such as haemorrhage, added to variations in carbon dioxide and oxygen tensions, may influence perfusion. Several of these circumstances may coincide and it is unclear how these may affect CBF.

OBJECTIVE

To describe the variation in transcranial Doppler and regional cerebral oxygen saturation (rSO2), as a surrogate of CBF, after cardiac preload and gravitational positional changes.

DESIGN

Observational study.

SETTING

Operating room at Hospital Clínic de Barcelona.

VOLUNTEERS

Ten healthy volunteers, white, both sexes.

INTERVENTIONS

Measurements were performed in the supine, sitting and standing positions during hyperoxia, hypocapnia and hypercapnia protocols and after a Valsalva manoeuvre.

MAIN OUTCOME MEASURES

Cardiac index (CI), haemodynamic and respiratory variables, maximal and mean velocities (Vmax, Vmean) (transcranial Doppler) and rSO2 were acquired. Results were analysed using a generalised estimating equation technique.

RESULTS

CI increases more than 16% after a preload challenge were not accompanied by differences in rSO2 or Vmax - Vmean. With positional changes, Vmean decreased more than 7% (P = 0.042) from the supine to the seated position. Hyperoxia induced a cerebral rSO2 increase more than 6% (P = 0.0001) with decreases in Vmax, Vmean and CI values more than 3% (P = 0.001, 0.022 and 0.001) in the supine and standing position. During hypocapnia, CI rose more than 20% from supine to seated and standing (P = 0.0001) with a 4.5% decrease in cerebral rSO2 (P = 0.001) and a decrease of Vmax - Vmean more than 24% in all positions (P = 0.001). Hypercapnia increased cerebral rSO2 more than 17% (P = 0.001), Vmax - Vmean more than 30% (P = 0.001) with no changes in CI. After a Valsalva manoeuvre, rSO2 decreased more than 3% in the right hemisphere in the upright position (P = 0.001). Vmax - Vmean decreased more than 10% (P = 0.001) with no changes in CI.

CONCLUSION

CBF changes in response to cerebral vasoconstriction and vasodilatation were detected with rSO2 and transcranial Doppler in healthy volunteers during cardiac preload and in different body positions. Acute hypercapnia had a greater effect on recorded brain parameters than hypocapnia.

The clinical effects of cerebral near-infrared spectroscopy monitoring (NIRS) versus no monitoring: a protocol for a systematic review with meta-analysis and trial sequential analysis

BACKGROUND

Multiple clinical conditions are associated with cerebral hypoxia/ischaemia and thereby an increased risk of hypoxic-ischaemic brain injury. Cerebral near-infrared spectroscopy monitoring (NIRS) is a tool to monitor brain oxygenation and perfusion, and the clinical uptake of NIRS has expanded over recent years. Specifically, NIRS is used in the neonatal, paediatric, and adult perioperative and intensive care settings. However, the available literature suggests that clinical benefits and harms of cerebral NIRS monitoring are uncertain. As rates of clinically significant hypoxic-ischaemic brain injuries are typically low, it is difficult for randomised clinical trials to capture a sufficiently large number of events to evaluate the clinical effect of cerebral NIRS monitoring, when focusing on specific clinical settings. The aim of this systematic review will be to evaluate the benefits and harms of clinical care with access to cerebral NIRS monitoring versus clinical care without cerebral NIRS monitoring in children and adults across all clinical settings.

METHODS

We will conduct a systematic review with meta-analysis and trial sequential analysis. We will only include randomised clinical trials. The primary outcomes are all-cause mortality, moderate or severe persistent cognitive or neurological deficit, and proportion of participants with one or more serious adverse events. We will search CENTRAL, EMBASE, MEDLINE, and the Science Citation Index Expanded from their inception and onwards. Two reviewers will independently screen all citations, full-text articles, and extract data. The risk of bias will be appraised using the Cochrane risk of bias tool version 2.0. If feasible, we will conduct both random-effects meta-analysis and fixed-effect meta-analysis of outcome data. Additional analysis will be conducted to explore the potential sources of heterogeneity (e.g. risk of bias, clinical setting).

DISCUSSION

As we include trials across multiple clinical settings, there is an increased probability of reaching a sufficient information size. However, heterogeneity between the included trials may impair our ability to interpret results to specific clinical settings. In this situation, we may have to depend on subgroup analyses with inherent increased risks of type I and II errors.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020202986 . This systematic review protocol has been submitted for registration in the International Prospective Register of Systematic Reviews (PROSPERO) (http://www.crd.york.ac.uk/prospero) on the 12th of October 2020 and published on the 12th of November 2020 (registration ID CRD42020202986 ).

Acute Ischemic Stroke

Anesthesiologists provide care to acute and subacute ischemic stroke (IS) patients and stroke survivors in interventional radiology, intensive care, and operating rooms. These encounters will become more frequent following studies that have extended the treatment window from last known well time for fibrinolytic and endovascular thrombectomy (EVT). The number of stroke centers certified to quickly and effectively initiate treatment of IS patients and the number of patients connected to them by telehealth continue to grow. This article reviews IS pathophysiology, assessment, treatment, pathology, and complications; anesthetic management during EVT; perioperative stroke management; and how anesthesia has an impact on patients with prior stroke.

Using non-invasive neuroimaging to enhance the care, well-being and experimental outcomes of laboratory non-human primates (monkeys)

Over the past 10-20 years, neuroscience witnessed an explosion in the use of non-invasive imaging methods, particularly magnetic resonance imaging (MRI), to study brain structure and function. Simultaneously, with access to MRI in many research institutions, MRI has become an indispensable tool for researchers and veterinarians to guide improvements in surgical procedures and implants and thus, experimental as well as clinical outcomes, given that access to MRI also allows for improved diagnosis and monitoring for brain disease. As part of the PRIMEatE Data Exchange, we gathered expert scientists, veterinarians, and clinicians who treat humans, to provide an overview of the use of non-invasive imaging tools, primarily MRI, to enhance experimental and welfare outcomes for laboratory non-human primates engaged in neuroscientific experiments. We aimed to provide guidance for other researchers, scientists and veterinarians in the use of this powerful imaging technology as well as to foster a larger conversation and community of scientists and veterinarians with a shared goal of improving the well-being and experimental outcomes for laboratory animals.

Cardiovascular outcomes in patients at high cardiovascular risk with previous myocardial infarction or stroke

BACKGROUND

Guidelines recommend to start blood pressure (BP)-lowering drugs also according to cardiovascular risk including history of cardiovascular events. We hypothesized that in patients with a history of myocardial infarction (MI), stroke, both or none of those, the index events predict the next event and have different SBP risk associations to different cardiovascular outcomes.

DESIGN AND MEASUREMENTS

In this pooled posthoc, nonprespecified analysis, we assessed outcome data from high-risk patients aged 55 years or older with a history of cardiovascular events or proven cardiovascular disease, randomized to the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial and to Telmisartan Randomized Assessment Study in ACE Intolerant Subjects with Cardiovascular Disease Trial investigating telmisartan, ramipril and their combination with a median follow-up of 56 months. Standardized office BP was measured every 6 months. Associations of mean achieved BP on treatment were investigated on MI, stroke and cardiovascular death. We identified patients with previous MI (N = 13 487), stroke (N = 4985), both (N = 1509) or none (N = 10 956) of these index events. Analyses were done by Cox regression, analysis of variance and Chi2-test. 30 937 patients with complete data were enrolled between 1 December 2001 and 31 July 2003, and followed until 31 July 2008. Data of both trials were pooled as the outcomes were similar.

RESULTS

Patients with MI as index event had a higher risk to experience a second MI [hazard ratio 1.42 (confidence interval (CI) 1.20-1.69), P < 0.0001] compared with patients with no events but no increased risk for a stroke as a next event [hazard ratio 0.95 (CI 0.73-1.23), n.s.]. The risk was roughly doubled when they had both, MI and stroke before [hazard ratio 2.07 (CI 1.58-2.71), P < 0.0001]. Patients with a stroke history had a roughly three-fold higher likelihood to experience a second stroke [hazard ratio 2.89 (CI 2.37-3.53) P < 0.0001] but not MI [hazard ratio 1.07 (CI 0.88-1.32), n.s.]. Both types of index events increased roughly three-fold the risk of a second stroke compared with no previous events. The SBP-risk relationship was not meaningfully altered by the event history. After MI and stroke the risk for subsequent events and cardiovascular death was increased over the whole SBP spectrum. A J-shape relationship between BP and outcome was only observed for cardiovascular death.

CONCLUSION

Previous MI and previous stroke are associated with increased risk for the same event in the future, independent of achieved SBP. Thus, secondary prevention may also be chosen according to the event history of patients.

CLINICAL TRIAL REGISTRATION

http://clinicaltrials.gov. Unique identifier: NCT00153101.

Intraoperative hypotension and perioperative acute ischemic stroke in patients having major elective non-cardiovascular non-neurological surgery

PURPOSE

The association between intraoperative hypotension and perioperative acute ischemic stroke is not well described. We hypothesized that intraoperative hypotension would be associated with perioperative acute ischemic stroke.

METHODS

Four-year retrospective cohort study of elective non-cardiovascular, non-neurological surgical patients. Characteristics of patients who had perioperative acute ischemic stroke were compared against those of patients who did not have acute ischemic stroke. Multivariable logistic regression was used to determine whether hypotension was independently associated with increased odds of perioperative acute ischemic stroke.

RESULTS

Thirty-four of 9816 patients (0.3%) who met study inclusion criteria had perioperative acute ischemic stroke. Stroke patients were older and had more comorbidities including hypertension, coronary artery disease, diabetes mellitus, active tobacco use, chronic obstructive pulmonary disease, cerebral vascular disease, atrial fibrillation, and peripheral vascular disease (all P < 0.05). MAP < 65 mmHg was not associated with increased odds of acute ischemic stroke when modeled as a continuous or categorical variable. MAP < 60 mmHg for more than 20 min was independently associated with increased odds of acute ischemic stroke, OR = 2.67 [95% CI = 1.21 to 5.88, P = 0.02].

CONCLUSION

Our analysis suggests that when MAP is less than 60 mmHg for more than 20 min, there is increased odds of acute ischemic stroke. Further studies are needed to determine what MAP should be targeted during surgery to optimize cerebral perfusion and limit ischemic stroke risk.

Middle cerebral artery pressure laterality in patients with symptomatic ICA stenosis

An internal carotid artery (ICA) stenosis can potentially decrease the perfusion pressure to the brain. In this study, computational fluid dynamics (CFD) was used to study if there was a hemispheric pressure laterality between the contra- and ipsilateral middle cerebral artery (MCA) in patients with a symptomatic ICA stenosis. We further investigated if this MCA pressure laterality (ΔP_MCA) was related to the hemispheric flow laterality (ΔQ) in the anterior circulation, i.e., ICA, proximal MCA and the proximal anterior cerebral artery (ACA). Twenty-eight patients (73±6 years, range 59–80 years, 21 men) with symptomatic ICA stenosis were included. Flow rates were measured using 4D flow MRI data (PC-VIPR) and vessel geometries were obtained from computed tomography angiography. The ΔP_MCA was calculated from CFD, where patient-specific flow rates were applied at all input- and output boundaries. The ΔP_MCA between the contra- and ipsilateral side was 6.4±8.3 mmHg (p<0.001) (median 3.9 mmHg, range -1.3 to 31.9 mmHg). There was a linear correlation between the ΔP_MCA and ΔQ_ICA (r = 0.85, p<0.001) and ΔQ_ACA (r = 0.71, p<0.001), respectively. The correlation to ΔQ_MCA was weaker (r = 0.47, p = 0.011). In conclusion, the MCA pressure laterality obtained with CFD, is a promising physiological biomarker that can grade the hemodynamic disturbance in patients with a symptomatic ICA stenosis.

Renal-Cerebral Pathophysiology: The Interplay Between Chronic Kidney Disease and Cerebrovascular Disease

OBJECTIVES

Cerebrovascular disease has increasingly been linked to overall vascular health. Pathologic conditions like diabetes, hypertension, and kidney disease have been shown to affect brain health and cerebrovascular and nervous systems. Acute kidney injury (AKI) and chronic Kidney Disease (CKD) represent a variety of vascular insults that can adversely affect cerebral health. Hypertension, fluctuations in blood pressure, and diabetic vasculopathy are known risk factors for cerebrovascular disease associated with CKD. Other emerging areas of interest include endothelial dysfunction, vascular calcification due to calcium and phosphorus metabolism dysregulation, and uremic neuropathy present the next frontier of investigation in CKD and cerebrovascular health.

METHODS

It has become apparent that the interrelation of AKI and CKD with vascular health, chemical homeostasis, and hormonal regulation upset many aspects of cerebral health and functioning. Stroke is an obvious connection, with CKD patients demonstrating a higher proclivity for cerebrovascular accidents. Cerebral bleeding risk, uremic neuropathies, sodium dysregulation with impacts on nervous system, vascular calcification, and endothelial dysfunction are the next salient areas of research that are likely to reveal key breakthroughs in renal-cerebral pathophysiology.

RESULTS

In this review nephrological definition are discussed in a neuro-centric manner, and the areas of key overlap between CKD and cerebrovascular pathology are discussed. The multifaceted effects of renal function on the health of the brain are also examined.

CONCLUSION

This review article aims to create the background for ongoing and future neurological-nephrological collaboration on understanding the special challenges in caring for patients with cerebrovascular disease who also have CKD.

Shock Severity and Hospital Mortality In Out of Hospital Cardiac Arrest Patients Treated With Targeted Temperature Management

BACKGROUND

Shock in patients resuscitated after out of hospital cardiac arrest (OHCA) is associated with an increased risk of mortality. We sought to determine the associations between lactate level, mean arterial pressure (MAP), and vasopressor/inotrope doses with mortality.

METHODS

Retrospective cohort study of adult patients with OHCA of presumed cardiac etiology treated with targeted temperature management (TTM) between December 2005 and September 2016. Multivariable logistic regression was performed to determine predictors of hospital death.

RESULTS

Among 268 included patients, the median age was 64 (55, 71.8) years, including 27% females. OHCA was witnessed in 89%, OHCA rhythm was shockable in 87%, and bystander CPR was provided in 64%. Vasopressors were required during the first 24 h in 60%. Hospital mortality occurred in 104 (38.8%) patients. Higher initial lactate, peak Vasoactive-Inotropic Score (VIS), and lower mean 24-h MAP were associated with higher hospital mortality (all P < 0.001). After multivariable regression, both higher initial lactate (adjusted OR 1.15 per 1 mmol/L higher, 95% CI 1.00-1.31, P = 0.03) and higher peak VIS (adjusted OR 1.20 per 10 units higher, 95% CI 1.10-1.54, P = 0.003) were associated with higher hospital mortality, but mMAP was not (P = 0.92). However, patients with a mMAP < 70 mm Hg remained at higher risk of hospital mortality after multivariable adjustment (adjusted OR 9.30, 95% CI 1.39-62.02, P = 0.02).

CONCLUSIONS

In patients treated with TTM after OHCA, greater shock severity, as reflected by higher lactate levels, mMAP < 70 mmHg, and higher vasopressor requirements during the first 24 h was associated with an increased rate of hospital mortality.

The effect of cardiac output on the pharmacokinetics and pharmacodynamics of propofol during closed-loop induction of anesthesia

BACKGROUND AND OBJECTIVE

Intraoperative hemodynamic stability is essential to safety and post-operative well-being of patients and should be optimized in closed-loop control of anesthesia. Cardiovascular changes inducing variations in pharmacokinetics may require dose modification. Rigorous investigational tools can strengthen current knowledge of the anesthesiologists and support clinical practice. We quantify the cardiovascular response of high-risk patients to closed-loop anesthesia and propose a new application of physiologically-based pharmacokinetic-pharmacodynamic (PBPK-PD) simulations to examine the effect of hemodynamic changes on the depth of hypnosis (DoH).

METHODS

We evaluate clinical hemodynamic changes in response to anesthesia induction in high-risk patients from a study on closed-loop anesthesia. We develop and validate a PBPK-PD model to simulate the effect of changes in cardiac output (CO) on plasma levels and DoH. The wavelet-based anesthetic value for central nervous system monitoring index (WAV_CNS) is used as clinical end-point of propofol hypnotic effect.

RESULTS

The median (interquartile range, IQR) changes in CO and arterial pressure (AP), 3 min after induction of anesthesia, are 22.43 (14.82-36.0) % and 26.60 (22.39-35.33) % respectively. The decrease in heart rate (HR) is less marked, i.e. 8.82 (4.94-12.68) %. The cardiovascular response is comparable or less enhanced than in manual propofol induction studies. PBPK simulations show that the marked decrease in CO coincides with high predicted plasma levels and deep levels of hypnosis, i.e. WAV_CNS < 40. PD model identification is improved using the PBPK model rather than a standard three-compartment PK model. PD simulations reveal that a 30% drop in CO can cause a 30% change in WAV_CNS.

CONCLUSIONS

Significant CO drops produce increased predicted plasma concentrations corresponding to deeper anesthesia, which is potentially dangerous for elderly patients. PBPK-PD model simulations allow studying and quantifying these effects to improve clinical practice.

The Hypotensive Role of Acupuncture in Hypertension: Clinical Study and Mechanistic Study

As a component of traditional Chinese medicine (TCM), acupuncture has the potential to lower blood pressure (BP) in patients with hypertension. Emerging evidence indicates that the acupuncture-induced inhibition of high BP occurs through the activation of the pathway in the afferent, central, and efferent pathways. An increasing number of studies have demonstrated that acupuncture not only activates distinct brain regions under conditions of hypertension caused by an imbalance between the sympathetic and parasympathetic systems but also modulates neurotransmitters in related brain regions to alleviate the autonomic response. The activity of these pathways can be assessed by injecting agonists or inhibitors or by performing neurotomy. This review focuses on the clinical and mechanistic studies of acupuncture in modulating BP, which might provide a neurobiological foundation for the effects of acupuncture. Although many mechanisms underlying the effects of acupuncture on cardiovascular function have been identified, further investigation is warranted.

Perioperative Quality Initiative (POQI) consensus statement on fundamental concepts in perioperative fluid management: fluid responsiveness and venous capacitance

Background

Optimal fluid therapy in the perioperative and critical care settings depends on understanding the underlying cardiovascular physiology and individualizing assessment of the dynamic patient state.

Methods

The Perioperative Quality Initiative (POQI-5) consensus conference brought together an international team of multidisciplinary experts to survey and evaluate the literature on the physiology of volume responsiveness and perioperative fluid management. The group used a modified Delphi method to develop consensus statements applicable to the physiologically based management of intravenous fluid therapy in the perioperative setting.

Discussion

We discussed the clinical and physiological evidence underlying fluid responsiveness and venous capacitance as relevant factors in fluid management and developed consensus statements with clinical implications for a broad group of clinicians involved in intravenous fluid therapy. Two key concepts emerged as follows: (1) The ultimate goal of fluid therapy and hemodynamic management is to support the conditions that enable normal cellular metabolic function in order to produce optimal patient outcomes, and (2) optimal fluid and hemodynamic management is dependent on an understanding of the relationship between pressure, volume, and flow in a dynamic system which is distensible with variable elastance and capacitance properties.

Successful Regional Anesthetic for a Parturient with Moyamoya Syndrome

Anesthesia for Cesarean section could be challenging due to the physiological changes during pregnancy, but it can be more complicated if associated with sickle cell disease and moyamoya disease. The moyamoya syndrome is nothing but sickle cell disease complicated by cerebral vasculopathy. Incidence of moyamoya disease in the USA is 0.086/100,000 people. We report a case of a pregnant woman with sickle cell disease and moyamoya syndrome, who underwent a successful spinal epidural for primary cesarean section, with careful monitoring of blood pressure.

Bilateral Visual Loss After Spine Surgery in a Patient With Midfacial Trauma: A Case Report

We present a case of bilateral visual loss in a patient who underwent spine surgery after sustaining a fall and trauma to her face and cervical spine. Visual loss in the right eye, not recognized until after surgery, was a result of blunt injury to the eye. Visual loss in the left eye was caused by posterior ischemic optic neuropathy, an unfortunate complication of surgery in the prone position.