Arterial pressure above the upper cerebral autoregulation limit during cardiopulmonary bypass is associated with postoperative delirium

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.

Prevalence of carotid artery stenosis and intra-cranial lesions in patients with aortic arch aneurysm and its association with intraoperative regional cerebral oxygen saturation and postoperative neurological outcomes

Background

Although aortic aneurysm is associated with vascular aging and atherosclerosis, carotid and intracranial vascular disease prevalence in patients with aortic arch aneurysm remains unclear. Similarly, the effect of carotid and intracranial lesions on postoperative outcomes is unknown. This study aimed to investigate the prevalence of carotid artery stenosis and intracranial lesions in patients with aortic arch aneurysm and its association with intraoperative regional cerebral oxygen saturation (rScO2) and postoperative neurological outcomes, including delirium and cerebral infarction.

Methods

This retrospective observational study included 133 patients with true aortic arch aneurysm who underwent preoperative magnetic resonance imaging (MRI). We evaluated the prevalence of carotid and intracranial arterial lesions. Symptomatic cerebral infarction and delirium, defined by the confusion assessment method for the intensive care unit, were evaluated for their association with preoperative cerebrovascular lesions. Additionally, changes in regional saturation of the cerebral tissue at different surgical phases were evaluated for patients with and without cerebrovascular lesions.

Results

Fifteen (11.3%) patients experienced symptomatic cerebral infarction, and 64 (48.1%) had postoperative delirium. Preoperative MRI showed old infarction, microbleeds, significant carotid artery stenosis, and intracranial lesions in 21.1%, 14.3%, 10.5%, and 7.5% of the patients, respectively. White matter hyperintensities with Fazekas scale 2 were observed in 40.6% of the patients, while Fazekas scale 3 were observed in 18.8% of the patients. Preoperative MRI findings and postoperative neurological outcomes were not significantly different. Seventy-six patients underwent rScO2 monitoring intraoperatively. Changes in rScO2 in patients with and without carotid/cerebrovascular lesions were not significantly different. However, rScO2 was significantly lower in patients who developed cerebral infarction.

Conclusions

Significant carotid artery stenosis and intracranial lesions were observed in 10.5% and 7.5% of the patients, respectively. Although preoperative MRI findings and changes in rScO2 or postoperative outcomes showed no significant association, patients with postoperative cerebral infarction showed significantly lower rScO2 intraoperatively.

Impact of postoperative cerebral complications in acute infective endocarditis: a retrospective single-center study

BACKGROUND

The treatment of patients with infective endocarditis (IE) who have preoperative cerebral complications remains less understood. Therefore, this study aimed to retrospectively evaluate the clinical outcomes of patients with acute IE based on preoperative intracranial findings.

METHODS

Of 32 patients with acute IE treated at our hospital between August 2015 and March 2022, 31 patients of whom preoperative intracranial imaging evaluation was available were included in our analysis and compared with those with and without intracranial findings. We controlled the mean arterial blood pressure and activated clotting time (ACT) to prevent abnormally high perfusion pressures and ACTs during cardiopulmonary bypass (CPB). The preoperative background, and postoperative courses focusing on postoperative brain complications were reviewed.

RESULTS

Among the 31 patients, 20 (65%) had preoperative imaging findings. The group with intracranial findings was significantly older, with more embolisms in other organs, positive intraoperative pathology findings, and longer CPB times. A new cerebral hemorrhage developed postoperatively in one patient without intracranial findings. There were no early deaths; two patients had recurrent infections in each group, and one died because of sepsis in the late phase in the group with intracranial findings.

CONCLUSIONS

Positive intracranial findings indicated significantly active infectious conditions preoperatively but did not affect the postoperative course. Patients without preoperative cerebral complications can develop serious cerebral hemorrhage. Although meticulous examination of preoperative cerebral complications in all patients with IE is essential, a strategy should be adopted to prevent cerebral hemorrhage, even in patients without intracranial findings.

Cerebral autoregulation-based mean arterial pressure targets and delirium in critically ill adults without brain injury: a retrospective cohort study

PURPOSE

Cerebral autoregulation (CA) is a mechanism that acts to maintain consistent cerebral perfusion across a range of blood pressures, and impaired CA is associated with delirium. Individualized CA-derived blood pressure targets are poorly characterized in critically ill patients and the association with intensive care unit (ICU) delirium is unknown. Our objectives were to characterize optimal mean arterial pressure (MAPopt) ranges in critically ill adults without brain injury and determine whether deviations from these targets contribute to ICU delirium.

METHODS

We performed a retrospective cohort analysis of patients with shock of any etiology and/or respiratory failure requiring invasive mechanical ventilation, without a neurologic admitting diagnosis. Patients were screened daily for delirium. Cerebral oximetry and mean arterial pressure data were captured for the first 24 hr from enrolment.

RESULTS

Forty-two patients with invasive blood pressure monitoring data were analyzed. Optimal mean arterial pressure targets ranged from 55 to 100 mm Hg. Optimal mean arterial pressure values were not significantly different based on history of hypertension or delirium status, and delirium was not associated with deviations from MAPopt. Nevertheless, the majority (69%) of blood pressure targets exceeded the current 65 mm Hg Surviving Sepsis guidelines.

CONCLUSION

We observed that MAPopt targets across patients were highly variable, but did not observe an association with the incidence of delirium. Studies designed to evaluate the impact on neurologic outcomes are needed to understand the association with individualized mean arterial pressure targets in the ICU.

STUDY REGISTRATION

ClinicalTrials.gov (NCT02344043); first submitted 22 January 2015.

Our initial experience of monitoring the autoregulation of cerebral blood flow during cardiopulmonary bypass

BACKGROUND

Cerebral blood flow (CBF) is believed to be relatively constant within an upper and lower blood pressure limit. Different methods are available to monitor CBF autoregulation during surgery. This study aims to critically analyze the application of the cerebral oxygenation index (COx), one of the commonly used techniques, using a reference to data from a series of clinical registrations.

METHOD

CBF was monitored using near-infrared spectroscopy, while cerebral blood pressure was estimated by recordings obtained from either the radial or femoral artery in 10 patients undergoing cardiopulmonary bypass. The association between CBF and blood pressure was calculated as a moving continuous correlation coefficient. A COx index > 0.4 was regarded as a sign of abnormal cerebral autoregulation (CA). Recordings were examined to discuss reliability measures and clinical feasibility of the measurements, followed by interpretation of individual results, identification of possible pitfalls, and suggestions of alternative methods.

RESULTS AND CONCLUSION

Monitoring of CA during cardiopulmonary bypass is intriguing and complex. A series of challenges and limitations should be considered before introducing this method into clinical practice.

The incidence, risk factors and outcomes of impaired cerebral autoregulation in aortic arch surgery: a single-center, retrospective cohort study

BACKGROUND

Impairment of cerebral autoregulation (CA) has been observed in patients undergoing cardiopulmonary bypass (CPB), but little is known about its risks and associations with outcomes. The cerebral oximetry index (COx), which is a moving linear correlation coefficient between regional cerebral oxygen saturation (rScO2) and mean blood pressure (MAP), may reflect CA function. When COx approaches 1, it implies that CA is damaged, whereas the CA is functional when the COx value approaches 0. The objective of this study was to analyze the incidence and risks of impaired CA, based on COx assessment, in patients undergoing total aortic arch replacement under systemic moderate hypothermia and circulatory arrest of the lower body (MHCA). We also evaluated the association between impaired CA and patient outcomes.

METHODS

One hundred and fifty-four adult patients who underwent total aortic arch replacement with stented elephant trunk implantation under MHCA at our hospital were retrospectively analyzed. Patients were defined as having new-onset impaired CA if pre-CPB COx < 0.3 and post-CPB COx > 0.3. Pre- and intraoperative factors were tested for independent association with impaired CA. Postoperative outcomes were compared between patients with normal and impaired CA.

RESULTS

In our 154 patients, 46(29.9%) developed new-onset impaired CA after CPB. Multivariable analysis revealed a prolonged low rScO2 (rScO2 < 55%) independently associated with onset of impaired CA, and receiver operating charactoristic curve showed a cutoff value at 40 min (sensitivity, 89.5%; specificity, 68.0%). Compared with normal CA patients, those with impaired CA showed a significantly higher rates of in-hospital mortality and postoperative complications.

CONCLUSIONS

Prolonged low rScO2 (rScO2 < 55%) during aortic arch surgery was closely related to onset of impaired CA. Impaired CA remained associated with the increased rates of postoperative complications and in-hospital mortality.

TRIAL REGISTRATION

ChiCTR1800014545 with registered date 20/01/2018.

Effects of Postoperative Blood Pressure Management on Delirium Among Patients in the Intensive Care Unit After Cardiac Surgery: An Observational Cohort Study

OBJECTIVES

This study aimed to determine whether blood pressure control in the early postoperative period was associated with postoperative delirium in the cardiovascular intensive care unit (ICU).

DESIGN

Observational cohort study.

SETTING

Single large academic institution with a high volume of cardiac surgery.

PARTICIPANTS

Cardiac surgery patients admitted to the cardiovascular ICU after surgery.

INTERVENTIONS

Observational study.

MEASUREMENTS AND MAIN RESULTS

A total of 517 cardiac surgery patients had mean arterial pressure (MAP) data recorded minute-by-minute for 12 postoperative hours. The time spent in each of the 7 prespecified blood pressure bands was calculated, and the development of delirium was recorded in the ICU. A multivariate Cox regression model was developed using the least absolute shrinkage and selection operator approach to identify associations between time spent in each MAP range band and delirium. Compared with the reference band of 60-to-69 mmHg, longer durations spent in 3 bands were independently associated with a lower risk of delirium: 50-to-59 mmHg band (adjusted hazard ratio [HR] 0.907 [per 10 minutes]; 95% CI 0.861-0.955); 70-to-79 mmHg band (adjusted HR 0.923 [per 10 minutes]; 95% CI 0.902-0.944); 90-to-99 mmHg band (adjusted HR 0.898 [per 10 minutes]; 95% CI 0.853-0.945).

CONCLUSIONS

The MAP range bands above and below the authors' reference band of 60-to- 69 mmHg were associated with decreased risk of ICU delirium development; however, this was difficult to reconcile with a plausible biologic mechanism. Therefore, the authors did not find a correlation between early postoperative MAP control and increased risk of the development of ICU delirium after cardiac surgery.

Investigation of the Optimum Baseline Blood Pressure for Spinal Anesthesia to Guide Vasopressor Management for Elective Cesarean Delivery: A Case-Control Design

BACKGROUND

Current guidelines recommend prophylactic vasopressor administration during spinal anesthesia for cesarean delivery to maintain intraoperative blood pressure above 90% of the baseline value. We sought to determine the optimum baseline mean arterial pressure (MAP) reading to guide the management of spinal hypotension.

METHODS

We performed a secondary analysis of data collected from normotensive patients presenting for elective cesarean delivery in a tertiary care institution from October 2018 to August 2020. We compared the magnitude of hypotension in patients who reported nausea versus those who did not, using a case-control design. Baseline MAPs at last office visit, morning of surgery, or operating room (pre-spinal) were determined. We calculated the duration and degree of hypotension using the area under the curve (AUC) when the MAP of the respective patient was below 90% of each baseline.

RESULTS

The patients who experienced nausea (n=45) had longer and more profound periods of hypotension than those who did not develop nausea (n=240). A comparison of AUC using MAP baseline at the last office visit or on the morning of surgery showed a statistically significant between-group difference, P=0.02, and P=0.005, respectively, and no significant between-group difference when 90% of the MAP baseline in the operating room was used.

CONCLUSIONS

Patients had the highest preoperative MAP in the operating room and the AUC was similar for those with and without nausea when the pre-spinal MAP baseline was used. Therefore, maintaining higher intraoperative blood pressure using individual pre-spinal MAP as baseline should reduce intraoperative maternal nausea.

Association between delirium and statin use in patients with congestive heart failure: a retrospective propensity score-weighted analysis

Background

The relationship between statin use and delirium remains controversial; therefore, we aimed to study the association between statin exposure and delirium and in-hospital mortality in patients with congestive heart failure.

Methods

In this retrospective study, patients with congestive heart failure were identified from the Medical Information Mart for Intensive Care database. The primary exposure variable was statin use 3 days after admission to the intensive care unit, and the primary outcome measure was the presence of delirium. The secondary outcome measure was in-hospital mortality. Since the cohort study was retrospective, we used inverse probability weighting derived from the propensity score to balance various variables.

Results

Of 8,396 patients, 5,446 (65%) were statin users. Before matching, the prevalence of delirium was 12.5% and that of in-hospital mortality was 11.8% in patients with congestive heart failure. Statin use was significantly negatively correlated with delirium, with an odds ratio of 0.76 (95% confidence interval: [0.66-0.87]; P < 0.001) in the inverse probability weighting cohort and in-hospital mortality of 0.66 (95% confidence interval: [0.58-0.75]; P < 0.001).

Conclusion

Statins administered in the intensive care unit can significantly reduce the incidence of delirium and in-hospital mortality in patients with congestive heart failure.

Monitoring the Cerebral Oximetry Index Along With In-line Cardiopulmonary Bypass Parameters in a High-Risk Patient Undergoing Cardiac Surgery: A Case Report

The quest to minimize the morbidity and mortality of patients undergoing cardiac surgery is ongoing. Impaired cerebral autoregulation and tissue malperfusion are linked with neurological complications. The cerebral oximetry index (COx) has been introduced as an index of cerebral autoregulation, while in-line monitoring enables the detection and prevention of metabolic disturbances during cardiopulmonary bypass (CPB). This report presents the case of a 58-year-old female patient scheduled for aortic valve replacement under minimally invasive extracorporeal circulation (MiECC). Her medical history consisted of epilepsy, multiple ischemic strokes, heavy smoking, and brachiocephalic artery stenosis. We sought to investigate the limits of autoregulation and the role of metabolic indices of perfusion on COx. Mean arterial blood pressure (ABP), cerebral oximetry (rSO₂), and in-line perfusion data during CPB were recorded at 10s intervals. The lower limit of autoregulation was 44mmHg on both sides and the upper limit was 98mmHg on the right and 107mmHg on the left side. A multiple linear regression analysis was performed to identify any potential predictors of COx values. Hemoglobin (Hb), PCO₂, flow, DO₂ index (DO₂i), Ο₂ extraction ratio (O₂ER), and perfusion ratio (PR) were included in the analysis. Significant equations were found on both sides. Predicted COx left was equal to 5.8 - 11.04O₂ER - 0.04Hb (p=0.001, R²= 0.15). Predicted COx right was equal to 3.06 - 0.3flow - 6.8O₂ER -0.03Hb + 0.02PCO₂ + 0.004DO₂i(p=0.03, R²=0.13). Targeting physiological perfusion and monitoring perfusion during CPB may have an additional impact on cerebral autoregulation and should be studied further.

Perioperative Neurocognitive Disorders in Adults Requiring Cardiac Surgery: Screening, Prevention, and Management

Neurocognitive changes are the most common complication after cardiac surgery, ranging from acute postoperative delirium to prolonged postoperative neurocognitive disorder. Changes in cognition are distressing to patients and families and associated with worse outcomes overall. This review outlines definitions and diagnostic criteria, risk factors for, and mechanisms of Perioperative Neurocognitive Disorders and offers strategies for preoperative screening and perioperative prevention and management of neurocognitive complications.

Refraining from Packed Red Blood Cells in Cardiopulmonary Bypass Priming as a Method of Neuroprotection in Pediatric Cardiac Surgery

Congenital heart defect (CHD) surgeries are performed with cardiopulmonary bypass (CPB) and are complicated by several factors that affect the child's brain. However, to date, the number of studies on brain protection in cardiac surgery remains small. The aim of this study was to assess the impact of refraining from using packed red blood cells (PRBCs) in priming solutions in children with congenital defects (CHDs) who require surgical interventions using CPB to prevent brain injury in the postoperative period.

MATERIAL AND METHODS

This study included 40 children, and the mean age was 14 (12-22.5) months and the mean weight was 8.8 (7.25-11) kg. All patients underwent CHD closure using CPB. The patients were divided into two groups depending on the use of PRBCs in the priming solution. Brain injury was assessed using three specific blood serum markers, namely S100 calcium-binding protein β (S100β), neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP) before surgery, after the completion of CPB and 16 h after surgery (first, second and third control points). Markers of systemic inflammatory response were also analyzed, including interleukin-1, -6, -10 and tumor necrosis factor alpha (TNF-α). A clinical assessment of brain injury was carried out using a valid, rapid, observational tool for screening delirium in children of this age group, i.e., "Cornell Assessment of Pediatric Delirium".

RESULTS

Factors of the intra- and postoperative period were analyzed, such as hemoglobin levels, oxygen delivery (cerebral tissue oxygenation, blood lactate level and venous oxygen saturation) and indicators of organ dysfunction (creatinine, urea, bilirubin levels, duration of CPB and length of stay in the ICU). Following the procedure, there were no significant differences between the groups and all indicators were within the reference values, thus demonstrating the safety of CHD closure without transfusion. Moreover, the highest level of specific markers of brain injury were noted immediately after the completion of CPB in both groups. The concentration of all three markers was significantly higher in the group with transfusion after the completion of CPB. Moreover, GFAP levels were higher in the transfusion group and 16 h after surgery.

CONCLUSIONS

The results of the study show the safety and effectiveness of brain injury prevention strategies that consist of not conducting PRBC transfusion.

Effectiveness of a multicomponent exercise training program for the management of delirium in hospitalized older adults using near-infrared spectroscopy as a biomarker of brain perfusion: Study protocol for a randomized controlled trial

Delirium is an important cause of morbidity and mortality in older adults admitted to hospital. Multicomponent interventions targeting delirium risk factors, including physical exercise and mobilization, have been shown to reduce delirium incidence by 30-40% in acute care settings. However, little is known about its role in the evolution of delirium, once established. This study is a randomized clinical trial conducted in the Acute Geriatric Unit of Hospital Universitario de Navarra (Pamplona, Spain). Hospitalized patients with delirium who meet the inclusion criteria will be randomly assigned to the intervention or the control group. The intervention will consist of a multicomponent exercise training program, which will be composed of supervised progressive resistance and strength exercise over 3 consecutive days. Functional Near-Infrared Spectroscopy (NIRS) will be used for assessing cerebral and muscle tissue blood flow. The objective is to assess the effectiveness of this intervention in modifying the following primary outcomes: duration and severity of delirium and functional status. This study will contribute to determine the effectiveness of physical exercise in the management of delirium. It will be the first study to evaluate the impact of a multicomponent intervention based on physical exercise in the evolution of delirium.

Clinical trial registration

ClinicalTrials.gov. identifier: NCT05442892 (date of registration June 26, 2022).

Effect of systolic blood pressure fluctuations during resuscitation on postoperative complications following meningioma surgery: A retrospective observation study

It is unclear whether blood pressure variability in the post-anesthesia care unit is associated with postoperative complications. This study aims to characterize the impact of blood pressure fluctuations on postoperative complications and postoperative length of stay after meningioma surgery. Adult meningioma patients undergoing general anesthesia were retrospectively recruited. The principal exposure was blood pressure variability in the post-anesthesia care unit, calculated by noninvasive blood pressure measurements. The primary outcome was major postoperative complications, defined as II or higher in the Clavien-Dindo classification grades. Secondary outcomes included healthcare resource utilization parameters among patients. Multivariable logistic regression was used and adjusted for potential confounding variables. Data sensitivity analyses were performed via different variable transformations and propensity score matching analyses. A total of 578 patients qualified for the study, and 161 (27.9%) cases experienced postoperative complications. The multivariable analysis found that increased systolic blood pressure variability in the post-anesthesia care unit was associated with postoperative complications (adjusted odds ratio [aOR] = 1.15; 95% confidence interval [CI], 1.09-1.22, P < .001) and prolonged postoperative length of stay (adjusted regression coefficients [β] = 1.86; 95% CI, 0.58-3.13, P = .004). Patients with postoperative complications had a higher frequency of intensive care admission (44.1% vs 15.3%), major postoperative interventions (6.6% vs 0%), and 30-day readmission (5.0% vs 0.7%). Systolic blood pressure fluctuations during resuscitation have an independent impact on postoperative complications and postoperative length of stay following meningioma surgery.

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.

High versus low blood pressure targets for cardiac surgery while on cardiopulmonary bypass

BACKGROUND

Cardiac surgery is performed worldwide. Most types of cardiac surgery are performed using cardiopulmonary bypass (CPB). Cardiac surgery performed with CPB is associated with morbidities. CPB needs an extracorporeal circulation that replaces the heart and lungs, and performs circulation, ventilation, and oxygenation of the blood. The lower limit of mean blood pressure to maintain blood flow to vital organs increases in people with chronic hypertension. Because people undergoing cardiac surgery commonly have chronic hypertension, we hypothesised that maintaining a relatively high blood pressure improves desirable outcomes among the people undergoing cardiac surgery with CPB.

OBJECTIVES

To evaluate the benefits and harms of higher versus lower blood pressure targets during cardiac surgery with CPB.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search of databases was November 2021 and trials registries in January 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing a higher blood pressure target (mean arterial pressure 65 mmHg or greater) with a lower blood pressure target (mean arterial pressure less than 65 mmHg) in adults undergoing cardiac surgery with CPB.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Primary outcomes were 1. acute kidney injury, 2. cognitive deterioration, and 3. all-cause mortality. Secondary outcomes were 4. quality of life, 5. acute ischaemic stroke, 6. haemorrhagic stroke, 7. length of hospital stay, 8. renal replacement therapy, 9. delirium, 10. perioperative transfusion of blood products, and 11. perioperative myocardial infarction. We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included three RCTs with 737 people compared a higher blood pressure target with a lower blood pressure target during cardiac surgery with CPB. A high blood pressure target may result in little to no difference in acute kidney injury (risk ratio (RR) 1.30, 95% confidence interval (CI) 0.81 to 2.08; I² = 72%; 2 studies, 487 participants; low-certainty evidence), cognitive deterioration (RR 0.82, 95% CI 0.45 to 1.50; I² = 0%; 2 studies, 389 participants; low-certainty evidence), and all-cause mortality (RR 1.33, 95% CI 0.30 to 5.90; I² = 49%; 3 studies, 737 participants; low-certainty evidence). No study reported haemorrhagic stroke. Although a high blood pressure target may increase the length of hospital stay slightly, we found no differences between a higher and a lower blood pressure target for the other secondary outcomes. We also identified one ongoing RCT which is comparing a higher versus a lower blood pressure target among the people who undergo cardiac surgery with CPB.

AUTHORS' CONCLUSIONS

A high blood pressure target may result in little to no difference in patient outcomes including acute kidney injury and mortality. Given the wide CIs, further studies are needed to confirm the efficacy of a higher blood pressure target among those who undergo cardiac surgery with CPB.

Timing, Threshold, and Duration of Intraoperative Hypotension in Cardiac Surgery: Their Associations With Postoperative Delirium

OBJECTIVES

To study the timing, threshold, and duration of intraoperative hypotension (IOH) associated with the risk of postoperative delirium (POD).

DESIGN

A single-center retrospective observational study.

SETTING

University teaching hospital.

PARTICIPANTS

A total of 503 adult patients who underwent cardiac valvular surgery that required cardiopulmonary bypass (CPB).

MEASUREMENTS AND MAIN RESULTS

The authors predefined the following 4 periods: (1) during surgery, (2) pre-CPB, (3) during CPB, and (4) post-CPB, and 8 thresholds of mean arterial pressure for IOH according to every 5 mmHg between 50 mmHg and 85 mmHg. The authors calculated the cumulative duration below the 8 thresholds in each period. The primary outcome was delirium defined as a score of ≥4 for at least one Intensive Care Delirium Screening Checklist assessment during 48 h after the surgery. Among 503 patients, POD occurred in 95 patients (18.9%). There was no significant association of POD with all of the thresholds of IOH in the periods of pre-CPB, during CPB, and during surgery. However, in the post-CPB period, the patients with POD had a significantly longer cumulative duration of IOH according to all of the thresholds of mean arterial pressure. In multivariate analyses, 4 IOH thresholds in the post-CPB period were associated independently with POD: <60 mmHg (odds ratio [OR] =1.84 [95% CI 1.10-3.10]), <65 mmHg (OR = 1.72 [1.01-2.92]), <70 mmHg (OR = 1.83 [1.03-3.26]), and <75 mmHg (OR = 1.94 [1.02-3.69]).

CONCLUSIONS

A longer cumulative duration of IOH with the threshold between <60 and <75 mmHg that occurred after CPB was independently associated with the risk of POD.

Intraoperative Hypotension and Acute Kidney Injury, Stroke, and Mortality during and outside Cardiopulmonary Bypass: A Retrospective Observational Cohort Study

BACKGROUND

In cardiac surgery, the association between hypotension during specific intraoperative phases or vasopressor-inotropes with adverse outcomes remains unclear. This study's hypothesis was that intraoperative hypotension duration throughout the surgery or when separated into hypotension during and outside cardiopulmonary bypass may be associated with postoperative major adverse events.

METHODS

This retrospective observational cohort study included data for adults who had cardiac surgery between 2008 and 2016 in a tertiary hospital. Intraoperative hypotension was defined as mean arterial pressure of less than 65 mmHg. The total duration of hypotension was divided into three categories based on the fraction of overall hypotension duration that occurred during cardiopulmonary bypass (more than 80%, 80 to 60%, and less than 60%). The primary outcome was a composite of stroke, acute kidney injury, or mortality during the index hospitalization. The association with the composite outcome was evaluated for duration of hypotension during the entire surgery, outside cardiopulmonary bypass, and during cardiopulmonary bypass and the fraction of hypotension during cardiopulmonary bypass adjusting for vasopressor-inotrope dose, milrinone dose, patient, and surgical factors.

RESULTS

The composite outcome occurred in 256 (5.1%) of 4,984 included patient records; 66 (1.3%) patients suffered stroke, 125 (2.5%) had acute kidney injury, and 109 (2.2%) died. The primary outcome was associated with total duration of hypotension (adjusted odds ratio, 1.05; 95% CI, 1.02 to 1.08; P = 0.032), hypotension outside cardiopulmonary bypass (adjusted odds ratio, 1.06; 95% CI, 1.03 to 1.10; P = 0.001) per 10-min exposure to mean arterial pressure of less than 65 mmHg, and fraction of hypotension duration during cardiopulmonary bypass of less than 60% (reference greater than 80%; adjusted odds ratio, 1.67; 95% CI, 1.10 to 2.60; P = 0.019) but not with each 10-min period hypotension during cardiopulmonary bypass (adjusted odds ratio, 1.04; 95% CI, 0.99 to 1.09; P = 0.118), fraction of hypotension during cardiopulmonary bypass of 60 to 80% (adjusted odds ratio, 1.45; 95% CI, 0.97 to 2.23; P = 0.082), or total vasopressor-inotrope dose (adjusted odds ratio, 1.00; 95% CI, 1.00 to 1.00; P = 0.247).

CONCLUSIONS

This study confirms previous single-center findings that intraoperative hypotension throughout cardiac surgery is associated with an increased risk of acute kidney injury, mortality, or stroke.

EDITOR’S PERSPECTIVE

Postoperative but not preoperative depression is associated with cognitive impairment after cardiac surgery: exploratory analysis of data from a randomized trial

BACKGROUND

In this study we hypothesize that depression is associated with perioperative neurocognitive dysfunction and altered quality of life one month after surgery.

METHODS

Data were obtained as part of a study evaluating cerebral autoregulation monitoring for targeting arterial pressure during cardiopulmonary bypass. Neuropsychological testing was performed before surgery and one month postoperatively. Testing included the Beck Depression Inventory, a depression symptoms questionnaire (0-63 scale), as well as anxiety and quality of life assessments. Depression was defined as a Beck Depression Inventory score > 13.

RESULTS

Beck Depression data were available from 320 patients of whom cognitive domain endpoints were available from 88-98% at baseline and 69-79% after surgery. This range in end-points data was due to variability in the availability of each neuropsychological test results between patients. Depression was present in 50 (15.6%) patients before surgery and in 43 (13.4%) after surgery. Baseline depression was not associated with postoperative domain-specific neurocognitive function compared with non-depressed patients. Those with depression one month after surgery, though, had poorer performance on tests of attention (p = 0.017), memory (p = 0.049), verbal fluency (p = 0.010), processing speed (p = 0.017), and fine motor speed (p = 0.014). Postoperative neurocognitive dysfunction as a composite outcome occurred in 33.3% versus 14.5% of patients with and without postoperative depression (p = 0.040). Baseline depression was associated with higher anxiety and lower self-ratings on several quality of life domains, these measures were generally more adversely affected by depression one month after surgery.

CONCLUSIONS

The results of this exploratory analysis suggests that preoperative depression is not associated with perioperative neurocognitive dysfunction, but depression after cardiac surgery may be associated with impairment in in several cognitive domains, a higher frequency of the composite neurocognitive outcome, and altered quality of life.

TRIAL REGISTRATION

www.

CLINICALTRIALS

gov, NCT00981474 (parent study).

High-resolution perioperative cerebral blood flow autoregulation measurement: a practical and feasible approach for widespread clinical monitoring

A growing body of evidence demonstrates that excursions of BP below or above the limits of cerebral blood flow autoregulation are associated with complications in patients with neurological injury or for those undergoing cardiac surgery. Moreover, recent evidence suggests that maintaining MAP above the lower limit of cerebral autoregulation during cardiopulmonary bypass reduces the frequency of postoperative delirium and is associated with improved memory 1 month after surgery. Continuous measurement of BP in relation to cerebral autoregulation limits using a virtual patient monitoring platform processing near-infrared spectroscopy digital signals offers the hope of bringing this application to the bedside.

Cerebral Autoregulation in Non-Brain Injured Patients: A Systematic Review

Introduction: Cerebral autoregulation (CA) plays a fundamental role in the maintenance of adequate cerebral blood flow (CBF). CA monitoring, through direct and indirect techniques, may guide an appropriate therapeutic approach aimed at improving CBF and reducing neurological complications; so far, the role of CA has been investigated mainly in brain-injured patients. The aim of this study is to investigate the role of CA in non-brain injured patients.

Methods: A systematic consultation of literature was carried out. Search terms included: “CA and sepsis,” “CA and surgery,” and “CA and non-brain injury.”

Results: Our research individualized 294 studies and after screening, 22 studies were analyzed in this study. Studies were divided in three groups: CA in sepsis and septic shock, CA during surgery, and CA in the pediatric population. Studies in sepsis and intraoperative setting highlighted a relationship between the incidence of sepsis-associated delirium and impaired CA. The most investigated setting in the pediatric population is cardiac surgery, but the role and measurement of CA need to be further elucidated.

Conclusion: In non-brain injured patients, impaired CA may result in cognitive dysfunction, neurological damage, worst outcome, and increased mortality. Monitoring CA might be a useful tool for the bedside optimization and individualization of the clinical management in this group of patients.

Cerebral monitoring in surgical ICU patients

PURPOSE OF REVIEW

To give an overview of cerebral monitoring techniques for surgical ICU patients.

RECENT FINDINGS

As the burden of postsurgical neurological and neurocognitive complications becomes increasingly recognized, cerebral monitoring in the surgical ICU might gain a relevant role in detecting and possibly preventing adverse outcomes. However, identifying neurological alterations in surgical ICU patients, who are often sedated and mechanically ventilated, can be challenging. Various noninvasive and invasive techniques are available for cerebral monitoring, providing an assessment of cortical electrical activity, cerebral oxygenation, blood flow autoregulation, intracranial pressure, and cerebral metabolism. These techniques can be used for the diagnosis of subclinical seizures, the assessment of sedation depth and delirium, the detection of an impaired cerebral blood flow, and the diagnosis of neurosurgical complications.

SUMMARY

Cerebral monitoring can be a valuable tool in the early detection of adverse outcomes in surgical ICU patients, but the evidence is limited, and clear clinical indications are still lacking.

Clinical values of cerebral oxygen saturation monitoring in patients with septic shock

OBJECTIVES

Sepsis associated encephalopathy (SAE) is a common neurological complication of sepsis. Delirium is a common symtom of SAE. The pathophysiology of SAE is still unclear, but several likely mechanisms have been proposed, such as mitochondrial and endothelial dysfunction, neurotransmission disturbances, derangements of calcium homeostasis, cerebral microcirculation dysfunction, and brain hypoperfusion. Near-infrared spectroscopy (NIRS) is a non-invasive measure for regional cerebral oxygen saturation (rSO2), which has attracted more attention these years. Previous studies have reported that abnormal NIRS values were associated with delirium in critically ill patients. Blood pressure management according to NIRS monitoring improved the organ perfusion and prognosis of patients. This study aimed to observe the dynamic changes of rSO2 using NIRS in septic shock patients, and analyze the relationship between them.

METHODS

A total of 48 septic patients who admitted to the intensive care unit (ICU) of Xiangya Hospital, Central South University from August 2017 to May 2018, were retrospectively study. Septic shock was diagnosed according to the criteria of sepsis 3.0 defined by the American Association of Critical Care Medicine and the European Society of Critical Care Medicine. NIRS monitoring was performed during the first 6 hours admitted to ICU with sensors placed on the bilateral forehead of patients. The maximum (rSO2max), minimum (rSO2min), mean value, and the variation rate during the first 6 hours of monitor were recorded. The following data were collected upon the first 24 h after admission to the ICU: The baseline data of patients, laboratory examination results (routine blood test, liver and renal function, blood gas analysis, indicators of infection, and coagulation function), scoring system results [Glasgow Coma Scale (GCS), Acute Physiology and Chronic Health Evaluation II (APACHE II) and Sequential Organ Failure Assessment (SOFA)]. Delirium was screened with the Confusion Assessment Method for ICU (CAM-ICU). The length of time on mechanical ventilation (MV), length of ICU-stay, length of hospital-stay, and 28-day mortality were also recorded. The primary outcome was 28-day mortality, and the secondary outcomes were the incidence of delirium, length of ICU-stay, and length of hospital-stay. The differences between survivors and non-survivors, and patients with or without delirium were analyzed, and the risk factors for delirium were assessed. The performance of rSO2-related indexes (rSO2max, rSO2min, the mean value, and the variation rate of rSO2) in predicting 28-day mortality and delirium was analyzed and the cutoff values were determined.

RESULTS

The overall 28-day mortality of septic shock patients was 47.92% (23/48), and the incidence of delirium was 18.75% (9/48). The rSO2min was significantly lower in the non-survivors than the survivors (P=0.042). The variation rate of rSO2 was higher in patients with delirium than those without delirium (P=0.006). The independent risk factors for delirium were rSO2max, the level of direct bilirubin (DBIL), and whether achieved the 6-hour bundle. To predict the 28-day mortality of septic shock patients, the area under the receiver operating characteristic curve (AUROC) for rSO2max, rSO2min, the mean value and the variation rate of rSO2 were 0.616, 0.606, 0.623, and 0.504, respectively. To predict the incidence of delirium, AUROC for rSO2max, rSO2min, the mean value and the variation rate of rSO2 were 0.682, 0.617, 0.580, and 0.501, respectively. The best cutoff value for rSO2max in predicting delirium was 77.5% (sensitivity was 0.444, specificity was 0.897). The best cutoff value for rSO2min in predicting delirium was 65.5% (sensitivity was 0.556, specificity was 0.744).

CONCLUSIONS

Cerebral anoxia and hyperoxia, as well as the large fluctuation of cerebral oxygen saturation are important factors that affect the outcomes and the incidence of delirium in septic shock patients, which should be paid attention to in clinical practice. Dynamic monitoring of cerebral oxygen saturation and maintain its stability may be of great significance in patients with septic shock.

Neurologic Complications of Surgery and Anesthesia

Surgery and anesthesia carry risks of ischemic, hemorrhagic, hypoxic, and metabolic complications, all of which can result in neurologic symptoms and deficits. Patients with underlying cardiovascular and cerebrovascular risk factors are particularly vulnerable. In this article the authors review the neurologic complications of surgery and anesthesia, with a focus on the role of the neurologic consultant in preoperative evaluation and risk stratification and diagnosis and management of postoperative complications.

Postoperative delirium and quality of life after transcatheter and surgical aortic valve replacement: A prospective observational study

OBJECTIVE

In older patients, postoperative delirium is a frequently occurring complication after surgical aortic valve replacement, leading to an excess in postoperative morbidity and mortality. It remains controversial whether transcatheter aortic valve implantation and minimally invasive surgical aortic valve replacement can reduce the risk of postoperative delirium. This study aimed to compare the incidence of postoperative delirium after transcatheter aortic valve implantation and surgical aortic valve replacement and the impact on long-term outcomes.

METHODS

Between September 2018 and January 2020, we conducted an observational, prospective cohort study in patients aged 70 years or more undergoing transcatheter aortic valve implantation or surgical aortic valve replacement. The primary end point was the incidence of in-hospital postoperative delirium during 5 postoperative days assessed with the Confusion Assessment Method. Secondary end points included perioperative inflammation, postoperative complications, health status (EuroQol 5-dimensional questionnaire 5 levels), and mortality up to 6 months. Transcatheter aortic valve implantation and surgical aortic valve replacement were compared using propensity weighting to account for important baseline differences (European System for Cardiac Operative Risk Evaluation II, age, and frailty).

RESULTS

We included 250 patients with a mean (standard deviation) age of 80 (±5.8) years and a European System for Cardiac Operative Risk Evaluation score of 5 (±4.7). In the propensity-weighted analysis, those undergoing surgical aortic valve replacement (N = 166) had a higher incidence of postoperative delirium compared with transcatheter aortic valve implantation (N = 84) (51% vs 15%: P < .0001). Furthermore, patients undergoing surgical aortic valve replacement experienced more inflammation, a greater depth of anesthesia, and more intraoperative hypotension. After surgical aortic valve replacement, 41% of patients experienced an improved health status compared with 12% after transcatheter aortic valve implantation (P < .0001). No outcome differences were noted within the surgical aortic valve replacement groups.

CONCLUSIONS

Transcatheter aortic valve implantation is associated with a lower risk for postoperative delirium. Nevertheless, patients undergoing surgical aortic valve replacement experience the greatest improvement in quality of life. Heart teams should consider these outcomes in shared decision-making in the choice of transcatheter aortic valve implantation or surgical aortic valve replacement.

Low Mean Arterial Pressure During Cardiopulmonary Bypass and the Risk of Acute Kidney Injury: A Propensity Score Matched Observational Study

INTRODUCTION

Low mean arterial pressure (MAP) periods occur frequently during cardiopulmonary bypass (CPB), and their management remains controversial. Our aim was to correlate MAP during CPB with the occurrence of post-operative acute kidney injury (AKI), considering two different parameters: consecutive and cumulative low MAP periods.

METHODS

Single-centre observational retrospective study including 250 patients submitted to non-emergent aortic valve replacement, with tepid to mild hypothermia (not below 32°C). The primary outcome was the occurrence of AKI. A propensity scored matching of 43 patients was used to adjust both populations (AKI and No AKI). MAP measures were automatically and continuously recorded during CPB. Low MAP periods were analysed employing two parameters: consecutive and the cumulative sum of time.

RESULTS

Patients who experienced at least 5 min with MAP <50 mmHg had an increased risk of post-operative AKI (OR infinity; 95% CI, 1.47 to infinity; P = .026). The risk is also significant with MAP <40 mmHg (OR 2.78; 95% CI 1.1-6.9; = .044) and <30 mmHg (OR 3.36; 95% CI 1.2-9.2; P = .029). Post-operative AKI was associated with cumulative and consecutive periods of low MAP. Patients with periods of low MAP had higher levels of post-operative creatinine and reduced glomerular filtration rate (GFR). Patients with AKI had prolonged endotracheal ventilation time, and ICU and ward lengths of stay.

CONCLUSION

Low MAP periods during CPB are associated with an increased occurrence of post-operative AKI, leading to 1) higher creatinine levels; 2) decreased GFR and 3) longer ICU and ward lengths of stay. Both consecutive and cumulative periods of low MAP are associated with an increased risk of AKI. MAP appears to be an important contributor to post-operative AKI and should be carefully managed during CPB. Further studies must address if MAP variations lead to definitive and long-term consequences.

Heterogeneous impact of hypotension on organ perfusion and outcomes: a narrative review

Arterial blood pressure is the driving force for organ perfusion. Although hypotension is common in acute care, there is a lack of accepted criteria for its definition. Most practitioners regard hypotension as undesirable even in situations that pose no immediate threat to life, but hypotension does not always lead to unfavourable outcomes based on experience and evidence. Thus efforts are needed to better understand the causes, consequences, and treatments of hypotension. This narrative review focuses on the heterogeneous underlying pathophysiological bases of hypotension and their impact on organ perfusion and patient outcomes. We propose the iso-pressure curve with hypotension and hypertension zones as a way to visualize changes in blood pressure. We also propose a haemodynamic pyramid and a pressure-output-resistance triangle to facilitate understanding of why hypotension can have different pathophysiological mechanisms and end-organ effects. We emphasise that hypotension does not always lead to organ hypoperfusion; to the contrary, hypotension may preserve or even increase organ perfusion depending on the relative changes in perfusion pressure and regional vascular resistance and the status of blood pressure autoregulation. Evidence from RCTs does not support the notion that a higher arterial blood pressure target always leads to improved outcomes. Management of blood pressure is not about maintaining a prespecified value, but rather involves ensuring organ perfusion without undue stress on the cardiovascular system.

Cerebral oximetry and preventing neurological complication post-cardiac surgery: a systematic review

OBJECTIVES

This systematic review aims to provide an up-to-date summary of the current literature examining the relationship between intraoperative regional cerebral oxygen saturation and neurological complications after cardiac surgery.

METHODS

Observational and interventional studies investigating the link between regional cerebral oxygen saturation and postoperative delirium, cognitive dysfunction and stroke were included. After database searching and study screening, study characteristics and major findings were extracted.

RESULTS

Twenty-seven studies were identified. Of the observational studies (n = 17), 8 reported that regional cerebral oxygen desaturations were significantly associated with neurological complications after cardiac surgery. Of the interventional studies (n = 10), 3 provided evidence for monitoring cerebral oximetry during cardiac surgery as a means of reducing incidence of postoperative cognitive dysfunction or stroke. There was significant heterogeneity in the tools and rigor used to diagnose neurological complications.

CONCLUSIONS

Studies to date show an inconsistent relationship between regional cerebral oxygen saturation and neurological outcomes after cardiac surgery, and lack of clear benefit of targeting cerebral oximetry to minimize neurological complications. Standardized assessments, definitions of impairment and desaturation thresholds will help determine the benefits of cerebral oximetry monitoring during cardiac surgery.

Dexmedetomidine reduces the incidence of postoperative delirium after cardiac surgery: a meta-analysis of randomized controlled trials

Background

The role of dexmedetomidine in preventing postoperative delirium (POD) after cardiac surgery remains controversial because of several recent trials with negative results. We aimed to perform an updated meta-analysis of randomized controlled trials (RCTs) to clarify this controversy.

Methods

RCTs investigating the perioperative administration of dexmedetomidine in cardiac surgery were retrieved from PubMed, Web of Science, and the Cochrane library until August,27,2020. Two researchers independently screened the literature, collected the data and evaluated the bias risk of the included studies. The meta-analysis was performed with the RevMan 5.3.

Results

A total of 15 studies including 2813 patients were included in the study. A pooled result showed that dexmedetomidine could reduce the risk of POD in adult population underwent cardiac surgery (OR 0.56, 95%CI 0.36–0.89, P = 0.0004, I² = 64%). The subgroup analysis demonstrated that the protective effect of dexmedetomidine was only present in the patients injected with dexmedetomidine after surgery but not from the start of surgery, in the adult patients without specific age limitation but not in the elderly, and in the studies in comparison with other sedatives but not with placebo. There were no statistical differences when analyzing the secondary outcomes including hypotension (OR 1.13; 95% CI 0.54–2.37, P < 0.00001, I² = 85%), bradycardia (OR 1.72; 95% CI 0.84–3.53, P = 0.04, I² = 58%) and atrial fibrillation (OR 0.87; 95% CI 0.70–1.08, P = 0.43, I² = 0).

Conclusions

Dexmedetomidine can reduce the incidence of POD compared to other sedatives and opioids after cardiac surgery in adult patients. The proper population and timing for perioperative use of dexmedetomidine after cardiac surgery remain to be further investigated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01370-1.

Intraoperative impaired cerebrovascular autoregulation and delayed neurocognitive recovery after major oncologic surgery: a secondary analysis of pooled data

Cerebral blood flow is tightly regulated by cerebrovascular autoregulation (CVA), and intraoperative impairment of CVA has been linked with perioperative neurocognitive disorders. We aim to assess whether impairment of CVA during major oncologic surgery is associated with delayed neurocognitive recovery (DNCR) postoperatively. We performed a secondary analysis of prospectively collected data. Patients were included if they had undergone complete pre- and postoperative neuropsychological assessments, continuous intraoperative measurement of CVA, and major oncologic surgery for visceral, urological, or gynecological cancer. Intraoperative CVA was measured using the time-correlation method based on near-infrared-spectroscopy, and DNCR was assessed with a neuropsychological test battery. A decline in cognitive function before hospital discharge compared with a preoperative baseline assessment was defined as DNCR. One hundred ninety-five patients were included in the analysis. The median age of the study population was 65 years (IQR: 60–68); 11 patients (5.6%) were female. Forty-one patients (21.0%) fulfilled the criteria for DNCR in the early postoperative period. We found a significant association between impaired intraoperative CVA and DNCR before hospital discharge (OR = 1.042 [95% CI: 1.005; 1.080], p = 0.028). The type of surgery (radical prostatectomy vs. other major oncologic surgery; OR = 0.269 [95% CI: 0.099; 0.728], p = 0.010) and premedication with midazolam (OR = 3.360 [95% CI: 1.039; 10.870], p = 0.043) were significantly associated with the occurrence of DNCR in the early postoperative period. Intraoperative impairment of CVA is associated with postoperative neurocognitive function early after oncologic surgery. Therefore, intraoperative monitoring of CVA may be a target for neuroprotective interventions. The initial studies were retrospectively registered with primary clinical trial registries recognized by the World Health Organization (ClinicalTrials.gov Identifiers: DRKS00010014, 21.03.2016 and NCT04101006, 24.07.2019).

Cerebral autoregulation in the operating room and intensive care unit after cardiac surgery

BACKGROUND

Cerebral autoregulation monitoring is a proposed method to monitor perfusion during cardiac surgery. However, limited data exist from the ICU as prior studies have focused on intraoperative measurements. Our objective was to characterise cerebral autoregulation during surgery and early ICU care, and as a secondary analysis to explore associations with delirium.

METHODS

In patients undergoing cardiac surgery (n=134), cerebral oximetry values and arterial BP were monitored and recorded until the morning after surgery. A moving Pearson's correlation coefficient between mean arterial proessure (MAP) and near-infrared spectroscopy signals generated the cerebral oximetry index (COx). Three metrics were derived: (1) globally impaired autoregulation, (2) MAP time and duration outside limits of autoregulation (MAP dose), and (3) average COx. Delirium was assessed using the 3-Minute Diagnostic Interview for CAM-defined Delirium (3D-CAM) and the Confusion Assessment Method for the ICU (CAM-ICU). Autoregulation metrics were compared using χ² and rank-sum tests, and associations with delirium were estimated using regression models, adjusted for age, bypass time, and logEuroSCORE.

RESULTS

The prevalence of globally impaired autoregulation was higher in the operating room vs ICU (40% vs 13%, P<0.001). The MAP dose outside limits of autoregulation was similar in the operating room and ICU (median 16.9 mm Hg×h; inter-quartile range [IQR] 10.1-38.8 vs 16.9 mm Hg×h; IQR 5.4-35.1, P=0.20). In exploratory adjusted analyses, globally impaired autoregulation in the ICU, but not the operating room, was associated with delirium. The MAP dose outside limits of autoregulation in the operating room and ICU was also associated with delirium.

CONCLUSIONS

Metrics of cerebral autoregulation are altered in the ICU, and may be clinically relevant with respect to delirium. Further studies are needed to investigate these findings and determine possible benefits of autoregulation-based MAP targeting in the ICU.

Cerebrovascular autoregulation and arterial carbon dioxide in patients with acute respiratory distress syndrome: a prospective observational cohort study

BACKGROUND

Early hypercapnia is common in patients with acute respiratory distress syndrome (ARDS) and is associated with increased mortality. Fluctuations of carbon dioxide have been associated with adverse neurological outcome in patients with severe respiratory failure requiring extracorporeal organ support. The aim of this study was to investigate whether early hypercapnia is associated with impaired cerebrovascular autoregulation during the acute phase of ARDS.

METHODS

Between December 2018 and November 2019, patients who fulfilled the Berlin criteria for ARDS, were enrolled. Patients with a history of central nervous system disorders, cerebrovascular disease, chronic hypercapnia, or a life expectancy of less than 24 h were excluded from study participation. During the acute phase of ARDS, cerebrovascular autoregulation was measured over two time periods for at least 60 min. Based on the values of mean arterial blood pressure and near-infrared spectroscopy, a cerebral autoregulation index (COx) was calculated. The time with impaired cerebral autoregulation was calculated for each measurement and was compared between patients with and without early hypercapnia [defined as an arterial partial pressure of carbon dioxide (PaCO2) ≥ 50 mmHg with a corresponding arterial pH < 7.35 within the first 24 h of ARDS diagnosis].

RESULTS

Of 66 patients included, 117 monitoring episodes were available. The mean age of the study population was 58.5 ± 16 years. 10 patients (15.2%) had mild, 28 (42.4%) moderate, and 28 (42.4%) severe ARDS. Nineteen patients (28.8%) required extracorporeal membrane oxygenation. Early hypercapnia was present in 39 patients (59.1%). Multivariable analysis did not show a significant association between early hypercapnia and impaired cerebrovascular autoregulation (B = 0.023 [95% CI - 0.054; 0.100], p = 0.556). Hypocapnia during the monitoring period was significantly associated with impaired cerebrovascular autoregulation [B = 0.155 (95% CI 0.014; 0.296), p = 0.032].

CONCLUSION

Our results suggest that moderate permissive hypercapnia during the acute phase of ARDS has no adverse effect on cerebrovascular autoregulation and may be tolerated to a certain extent to achieve low tidal volumes. In contrast, episodes of hypocapnia may compromise cerebral blood flow regulation. Trial registration ClinicalTrials.gov; registration number: NCT03949738; date of registration: May 14, 2019.

Stroke Rates Following Surgical Versus Percutaneous Revascularization for Ischemic Heart Disease

PURPOSE OF REVIEW

Coronary revascularization is a commonly performed major procedure in the hospitals. Stroke is one of the dreaded complications after coronary revascularization procedures. The focus of this review is to understand the stroke risk in percutaneous cutaneous intervention (PCI) and coronary artery bypass grafting (CABG) procedures.

RECENT FINDINGS

Available data show that PCI offers less procedural stroke risk compared to CABG although the survival benefits of CABG are better in certain scenarios. Innovative advancements in techniques, pre-procedural optimum medical therapy (OMT), intraoperative neuro-monitoring, and multidisciplinary post procedural care are the few strategies in early detection and reduce stroke risk. Despite several innovations and strategies, it is evident that there is not enough data available to make concrete conclusions related to stroke risk after coronary revascularization, which warrants further investigation.

The role of diffuse correlation spectroscopy and frequency-domain near-infrared spectroscopy in monitoring cerebral hemodynamics during hypothermic circulatory arrests

Objectives

Real-time noninvasive monitoring of cerebral blood flow (CBF) during surgery is key to reducing mortality rates associated with adult cardiac surgeries requiring hypothermic circulatory arrest (HCA). We explored a method to monitor cerebral blood flow during different brain protection techniques using diffuse correlation spectroscopy (DCS), a noninvasive optical technique which, combined with frequency-domain near-infrared spectroscopy (FDNIRS), also provides a measure of oxygen metabolism.

Methods

We used DCS in combination with FDNIRS to simultaneously measure hemoglobin oxygen saturation (SO₂), an index of cerebral blood flow (CBF_i), and an index of cerebral metabolic rate of oxygen (CMRO_2i) in 12 patients undergoing cardiac surgery with HCA.

Results

Our measurements revealed that a negligible amount of blood is delivered to the cerebral cortex during HCA with retrograde cerebral perfusion, indistinguishable from HCA-only cases (median CBF_i drops of 93% and 95%, respectively) with consequent similar decreases in SO₂ (mean decrease of 0.6 ± 0.1% and 0.9 ± 0.2% per minute, respectively); CBF_i and SO₂ are mostly maintained with antegrade cerebral perfusion; the relationship of CMRO_2i to temperature is given by CMRO_2i = 0.052e^0.079T.

Conclusions

FDNIRS-DCS is able to detect changes in CBF_i, SO₂, and CMRO_2i with intervention and can become a valuable tool for optimizing cerebral protection during HCA.

Postoperative Neurocognitive Disorders in Cardiac Surgery: Investigating the Role of Intraoperative Hypotension. A Systematic Review

Perioperative neurocognitive disorders remain a challenging obstacle in patients after cardiac surgery, as they significantly contribute to postoperative morbidity and mortality. Identifying the modifiable risk factors and mechanisms for postoperative cognitive decline (POCD) and delirium (POD) would be an important step forward in preventing such adverse events and thus improving patients’ outcome. Intraoperative hypotension is frequently discussed as a potential risk factor for neurocognitive decline, due to its significant impact on blood flow and tissue perfusion, however the studies exploring its association with POCD and POD are very heterogeneous and present divergent results. This review demonstrates 13 studies found after structured systematic search strategy and discusses the possible relationship between intraoperative hypotension and postoperative neuropsychiatric dysfunction.

Relationship between endothelial function and vascular stiffness on lower limit of cerebral autoregulation in patients undergoing cardiovascular surgery

Hemodynamic management based on cerebral autoregulation range is a possible strategy for preserving major organ perfusion during cardiovascular surgery. The purpose of this study was to evaluate the relation of vascular properties with lower limit of cerebral autoregulation (LLA). LLA was monitored in 66 patients undergoing cardiovascular surgery using near-infrared spectroscopy. To determine the clinical importance of LLA monitoring, association of blood pressure excursions below LLA and acute kidney injury (AKI) was evaluated. Flow-mediated dilation (FMD) and pulse wave velocity (PWV) were measured for the evaluation of endothelial function and aortic stiffness. Variables associated with LLA were evaluated. Excluding patients on hemodialysis, there were 15 patients (25.9%) who developed AKI. Blood pressure excursions below LLA were higher in patients who developed AKI (4.55 mm Hg × hr vs. 1.23 mm Hg × hr, P = .017). In the univariate analysis, prevalence of ischemic heart disease (No IHD: 53 ± 13.0 mm Hg vs. IHD: 60.0 ± 13.6 mm Hg, P = .056) and FMD (r = -0.42, 95% CI -0.61 to -0.19, P < .001) were associated with LLA before cardiopulmonary bypass (CPB). During CPB, calcium channel blocker (No Ca blocker: 42 ± 10.6 mm Hg vs. Ca blocker: 49 ± 14.3 mm Hg, P = .033), diabetes (no DM: 44 ± 13.2 mm Hg vs. DM: 55 ± 10.0 mm Hg, P = .024), FMD (r = -0.32, 95% CI -0.55 to -0.05, P = .021), and PWV (r = 0.28, 95% CI 0.012 to 0.513, P = .041) were associated with LLA. Multivariate analysis showed that FMD was correlated with LLA before CPB (r = -2.19, 95% CI -3.621 to -0.755, P = .003), while PWV was correlated with LLA during CPB (r = 0.01, 95% CI 0.001-0.019, P = .023). Endothelial function and aortic stiffness may be important factors in determining LLA at different phases in cardiovascular surgery.

Brain Protection in Aortic Arch Surgery: An Evolving Field

Despite advances in cardiac surgery and anesthesia, the rates of brain injury remain high in aortic arch surgery requiring circulatory arrest. The mechanisms of brain injury, including permanent and temporary neurologic dysfunction, are multifactorial, but intraoperative brain ischemia is likely a major contributor. Maintaining optimal cerebral perfusion during cardiopulmonary bypass and circulatory arrest is the key component of intraoperative management for aortic arch surgery. Various brain monitoring modalities provide different information to improve cerebral protection. Electroencephalography gives crucial data to ensure minimal cerebral metabolism during deep hypothermic circulatory arrest, transcranial Doppler directly measures cerebral arterial blood flow, and near-infrared spectroscopy monitors regional cerebral oxygen saturation. Various brain protection techniques, including hypothermia, cerebral perfusion, pharmacologic protection, and blood gas management, have been used during interruption of systemic circulation, but the optimal strategy remains elusive. Although deep hypothermic circulatory arrest and retrograde cerebral perfusion have their merits, there have been increasing reports about the use of antegrade cerebral perfusion, obviating the need for deep hypothermia. With controversy and variability of surgical practices, moderate hypothermia, when combined with unilateral antegrade cerebral perfusion, is considered safe for brain protection in aortic arch surgery performed with circulatory arrest. The neurologic outcomes of brain protection in aortic arch surgery largely depend on the following three major components: cerebral temperature, circulatory arrest time, and cerebral perfusion during circulatory arrest. The optimal brain protection strategy should be individualized based on comprehensive monitoring and stems from well-executed techniques that balance the major components contributing to brain injury.

Decrease of Coronal Optic Nerve Sheath Diameter is Associated With Postoperative Cognitive Decline in Patients Undergoing Carotid Endarterectomy

OBJECTIVE

Patients undergoing carotid endarterectomy (CEA) have a significant possibility of developing postoperative cognitive decline (POCD). POCD after surgery could be result from cerebral hypotension induced by cross-clamping or postoperative hyperperfusion. Optic nerve sheath diameter (ONSD) exhibits an excellent correlation with invasive intracranial pressure monitoring, Here, the authors explored the risk factors of POCD in patients undergoing CEA, paying close attention to ONSD to test the hypothesis that decrease of coronal ONSD was related to the incidence of POCD.

DESIGN

Observational retrospective review.

SETTING

Single tertiary academic center.

PARTICIPANTS

One hundred sixteen patients undergoing CEA from January 1, 2019 to December 31, 2019.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

A multivariate logistic regression, scatter diagrams, and a receiver operating curve were used to evaluate the ability to predict POCD though the change in coronal ONSD. This study ultimately enrolled 84 patients and the incidence of POCD within postoperative two days was 28.6%. Decrease of coronal ONSD (odds ratio [OR], 0.438; 95% confidence interval [CI] 0.217-0.881; p = 0.021) and total intravenous anesthesia (TIVA) (OR, 25.541, 95% CI 2.100-310.614, p = 0.011) were independent risk factors for POCD. Changes in coronal ONSD had an area under the curve to distinguish POCD of 0.716 (95% CI 0.531-0.902). Using a cutoff of 0.05 cm, changes of coronal ONSD had a sensitivity of 66.7% and specificity of 66.7%.

CONCLUSIONS

Decrease of coronal ONSD, measured by ultrasonography and TIVA, were associated with POCD. Change in coronal ONSD was a moderate predictor of incidence of POCD.

Considerations for Reduction of Risk of Perioperative Stroke in Adult Patients Undergoing Cardiac and Thoracic Aortic Operations: A Scientific Statement From the American Heart Association

Perioperative stroke is one of the most severe and feared complications of cardiac surgery. Based on the timing of onset and detection, perioperative stroke can be classified as intraoperative or postoperative. The pathogenesis of perioperative stroke is multifactorial, which makes prediction and prevention challenging. However, information on its incidence, mechanisms, diagnosis, and treatment can be helpful in minimizing the perioperative neurological risk for individual patients. We herein provide suggestions on preoperative, intraoperative, and postoperative strategies aimed at reducing the risk of perioperative stroke and at improving the outcomes of patients who experience a perioperative stroke.

Noninvasive neuromonitoring in the operating room and its role in the prevention of delirium

Delirium is a frequent and serious complication after surgery. It has a variable incidence between 20% and 40% with the highest incidence in elderly people undergoing major or cardiac surgery. The development of postoperative delirium (POD) is associated with increased hospital stay lengths, morbidity, the need for home care, and mortality. Studies have appeared in the last decade that evaluate the use of noninvasive monitoring to prevent its development. The evaluation of the depth of anesthesia with processed EEG allows to avoid awareness and burst suppression events. The cessation of brain activity is associated with the development of delirium. Another noninvasive monitoring technique is NIRS for cerebral tissue hypoxia detection by measuring regional oxygen saturation. The reduction of this parameter does not seem to be associated with the development of POD but with postoperative cognitive dysfunction. There are few studies in the literature and with conflicting results on the use of the pupillometer and transcranial Doppler in predicting the development of postoperative delirium.

[Near-infrared spectroscopy : Technique, development, current use and perspectives]

Near-infrared spectroscopy (NIRS) has been available in research and clinical practice for more than four decades. Recently, there have been numerous publications and substantial developments in the field. This article describes the clinical application of NIRS in relation to current guidelines, with a focus on pediatric and cardiac anesthesia. It discusses technical and physiological principles, pitfalls in clinical use and presents (patho)physiological influencing factors and derived variables, such as fractional oxygen extraction (FOE) and the cerebral oxygen index (COx). Recommendations for the interpretation of NIRS values in connection with influencing factors, such as oxygen transport capacity, gas exchange and circulation as well as an algorithm for cardiac anesthesia are presented. Limitations of the method and the lack of comparability of values from different devices as well as generally accepted standard values are explained. Technical differences and advantages compared to pulse oxymetry and transcranial Doppler sonography are illuminated. Finally, the prognostic significance and requirements for future clinical studies are discussed.

Perioperative neurocognitive dysfunction: thinking from the gut?

With the aging of the world population, and improvements in medical and health technologies, there are increasing numbers of elderly patients undergoing anaesthesia and surgery. Perioperative neurocognitive dysfunction has gradually attracted increasing attention from academics. Very recently, 6 well-known journals jointly recommended that the term perioperative neurocognitive dysfunction (defined according to the Diagnostic and Statistical Manual of Mental Disorders, fifth edition) should be adopted to improve the quality and consistency of academic communications. Perioperative neurocognitive dysfunction currently includes preoperatively diagnosed cognitive decline, postoperative delirium, delayed neurocognitive recovery, and postoperative cognitive dysfunction. Increasing evidence shows that the gut microbiota plays a pivotal role in neuropsychiatric diseases, and in central nervous system functions via the microbiota-gut-brain axis. We recently reported that abnormalities in the composition of the gut microbiota might underlie the mechanisms of postoperative cognitive dysfunction and postoperative delirium, suggesting a critical role for the gut microbiota in perioperative neurocognitive dysfunction. This article therefore reviewed recent findings on the linkage between the gut microbiota and the underlying mechanisms of perioperative neurocognitive dysfunction.