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.

Role of Cognitive Frailty in Older Adults With Cardiovascular Disease

As the older adult population expands, an increasing number of patients affected by geriatric syndromes are seen by cardiovascular clinicians. One such syndrome that has been associated with poor outcomes is cognitive frailty: the simultaneous presence of cognitive impairment, without evidence of dementia, and physical frailty, which results in decreased cognitive reserve. Driven by common pathophysiologic underpinnings (eg, inflammation and neurohormonal dysregulation), cardiovascular disease, cognitive impairment, and frailty also share the following risk factors: hypertension, diabetes, obesity, sedentary behavior, and tobacco use. Cardiovascular disease has been associated with the onset and progression of cognitive frailty, which may be reversible in early stages, making it essential for clinicians to diagnose the condition in a timely manner and prescribe appropriate interventions. Additional research is required to elucidate the mechanisms underlying the development of cognitive frailty, establish preventive and therapeutic strategies to address the needs of older patients with cardiovascular disease at risk for cognitive frailty, and ultimately facilitate targeted intervention studies.

Continuous Monitoring of Cerebral Autoregulation in Adults Supported by Extracorporeal Membrane Oxygenation

BACKGROUND

Impaired cerebral autoregulation (CA) is one of several proposed mechanisms of acute brain injury in patients supported by extracorporeal membrane oxygenation (ECMO). The primary aim of this study was to determine the feasibility of continuous CA monitoring in adult ECMO patients. Our secondary aims were to describe changes in cerebral oximetry index (COx) and other metrics of CA over time and in relation to functional neurologic outcomes.

METHODS

This is a single-center prospective observational study. We measured COx, a surrogate measurement of cerebral blood flow measured by near-infrared spectroscopy, which is an index of CA derived from the moving correlation between mean arterial pressure (MAP) and slow waves of regional cerebral oxygen saturation. A COx value that approaches 1 indicates impaired CA. Using COx, we determined the optimal MAP (MAPOPT) and lower and upper limits of autoregulation for individual patients. These measurements were examined in relation to modified Rankin Scale (mRS) scores.

RESULTS

Fifteen patients (median age 57 years [interquartile range 47-69]) with 150 autoregulation measurements were included for analysis. Eleven were on veno-arterial ECMO (VA-ECMO), and four were on veno-venous ECMO (VV-ECMO). Mean COx was higher on postcannulation day 1 than on day 2 (0.2 vs. 0.09, p < 0.01), indicating improved CA over time. COx was higher in VA-ECMO patients than in VV-ECMO patients (0.12 vs. 0.06, p = 0.04). Median MAPOPT for the entire cohort was highly variable, ranging from 55 to 110 mm Hg. Patients with mRS scores 0-3 (good outcome) at 3 and 6 months spent less time outside MAPOPT compared with patients with mRS scores 4-6 (poor outcome) (74% vs. 82%, p = 0.01). The percentage of time when observed MAP was outside the limits of autoregulation was higher on postcannulation day 1 than on day 2 (18.2% vs. 3.3%, p < 0.01).

CONCLUSIONS

In ECMO patients, it is feasible to monitor CA continuously at the bedside. CA improved over time, most significantly between postcannulation days 1 and 2. CA was more impaired in VA-ECMO patients than in VV-ECMO patients. Spending less time outside MAPOPT may be associated with achieving a good neurologic outcome.

Poor olfaction prior to cardiac surgery: Association with cognition, plasma neurofilament light, and post-operative delirium

OBJECTIVES

Post-operative delirium (POD) affects up to 50% of cardiac surgery patients, with higher incidence in older adults. There is increasing need for screening tools that identify individuals most vulnerable to POD. Here, we examined the relationship between pre-operative olfaction and both incident POD and POD severity in patients undergoing cardiac surgery. We also examined cross-sectional relationships between baseline olfaction, cognition, and plasma neurofilament light (NfL).

METHODS

Individuals undergoing cardiac surgery (n = 189; mean age = 70 years; 75% men) were enrolled in a clinical trial of cerebral autoregulation monitoring. At baseline, odor identification performance (Brief Smell Identification Test), cognitive performance, and plasma concentrations of NfL levels (Simoa™ NF-Light Assay) were measured. Delirium was assessed with the Confusion Assessment Method (CAM) or CAM-ICU, and delirium severity was assessed using the Delirium Rating Scale-Revised-98. The association of baseline olfaction, delirium incidence, and delirium severity was examined in regression models adjusting for age, duration of cardiopulmonary bypass, logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE), and baseline cognition.

RESULTS

Olfactory dysfunction was present in 30% of patients, and POD incidence was 44%. Pre-operative olfactory dysfunction was associated with both incident POD (OR = 3.17, p = 0.001) and greater severity of POD after cardiac surgery (OR = 3.94 p < 0.001) in models adjusted for age, duration of bypass, and a surgical risk score. The addition of baseline cognition attenuated the strength of the association, but it remained significant for incident POD (OR = 2.25, p = 0.04) and POD severity (OR 2.10, p = 0.04). Poor baseline olfaction was associated with greater baseline cognitive dysfunction (p < 0.001) and increased baseline plasma NfL concentrations (p = 0.04). Neither age, cognition, nor baseline NFL concentration modified the association of impaired olfaction and delirium outcomes.

CONCLUSIONS

Olfactory assessment may be a useful pre-surgical screening tool for the identification of patients undergoing cardiac surgery at increased risk of POD. Identifying those at highest risk for severe delirium and poor cognitive outcomes following surgery would allow for earlier intervention and pre-operative rehabilitation strategies, which could ultimately impact the functional disability and morbidity associated with POD.

Association of perioperative plasma concentration of neurofilament light with delirium after cardiac surgery: a nested observational study

BACKGROUND

Neurofilament light is a blood-based biomarker of neuroaxonal injury that can provide insight into perioperative brain vulnerability and injury. Prior studies have suggested that increased baseline and postoperative concentrations of neurofilament light are associated with delirium after noncardiac surgery, but results are inconsistent. Results have not been reported in cardiac surgery patients, who are among those at highest risk for delirium. We hypothesised that perioperative blood concentrations of neurofilament light (both baseline and change from baseline to postoperative day 1) are associated with delirium after cardiac surgery.

METHODS

This study was nested in a trial of arterial blood pressure targeting during cardiopulmonary bypass using cerebral autoregulation metrics. Blood concentrations of neurofilament light were measured at baseline and on postoperative day 1. The primary outcome was postoperative delirium. Regression models were used to examine the associations between neurofilament light concentration and delirium and delirium severity, adjusting for age, sex, race, logistic European System for Cardiac Operative Risk Evaluation, bypass duration, and cognition.

RESULTS

Delirium occurred in 44.6% of 175 patients. Baseline neurofilament light concentration was higher in delirious than in non-delirious patients (median 20.7 pg ml-1 [IQR 16.1-33.2] vs median 15.5 pg ml-1 [IQR 12.1-24.2], P<0.001). In adjusted models, greater baseline neurofilament light concentration was associated with delirium (odds ratio, 1.027; 95% confidence interval, 1.003-1.053; P=0.029) and delirium severity. From baseline to postoperative day 1, neurofilament light concentration increased by 42%, but there was no association with delirium.

CONCLUSIONS

Baseline neurofilament light concentration, but not change from baseline to postoperative day 1, was associated with delirium after cardiac surgery.

B - 92 Poor Olfaction Prior to Cardiac Surgery: Associations with Cognition, Plasma Neurofilament Light and Postoperative Delirium in a Prospective Nested Cohort Study

OBJECTIVE

This study examined the association between pre-operative olfactory performance and delirium after cardiac surgery. As a secondary aim, we examined the relationship between baseline olfaction, cognitive functioning, and plasma neurofilament light (NfL).

METHOD

Individuals undergoing cardiac surgery were recruited as part of a clinical trial in which blood pressure during bypass was targeted using cerebral autoregulation monitoring. There were 189 participants (mean age = 70 years; 75% men). At baseline, olfaction, cognition, and plasma concentrations of NfL were assessed using the 12-item Brief Smell Identification Test (BSIT), a battery of neuropsychological tests, and the Simoa™ NF-Light Assay, respectively. Impaired olfaction was defined as a score of ≤8 for men and ≤ 9 for women. Delirium was assessed using the Confusion Assessment Method (CAM) and CAM-ICU, and delirium severity was assessed using the Delirium Rating Scale-Revised-1998 (DRS-R-98). The association of baseline olfaction and delirium and delirium severity was examined in regression models adjusting for age, duration of bypass, a surgery risk score, and baseline cognitive performance.

RESULTS

In adjusted models, impaired olfaction at baseline was associated with both incident delirium (OR = 2.25, p = 0.04) and greater delirium severity (OR = 2.10, p = 0.04) after cardiac surgery. Furthermore, worse baseline olfaction was associated with impaired cognition (p < 0.001) and increased perioperative concentrations of plasma NfL (p = 0.04).

CONCLUSIONS

Pre-operative olfactory testing may provide insight into brain vulnerability, cognitive dysfunction, and delirium risk in individuals undergoing cardiac surgery. Psychophysical olfactory assessment may inform strategies for patient risk stratification and early identification of individuals at risk for post-operative delirium, allowing for delirium-prevention strategies.

Continuous Monitoring of Cerebral Autoregulation in Adults Supported by Extracorporeal Membrane Oxygenation

Background

Impaired cerebral autoregulation (CA) is one of several proposed mechanisms of acute brain injury in patients supported by extracorporeal membrane oxygenation (ECMO). The primary aim of this study was to determine the feasibility of continuous CA monitoring in adult ECMO patients. Our secondary aims were to describe changes in cerebral oximetry index (COx) and other metrics of CA over time and in relation to functional neurologic outcomes.

Methods

This is a single-center prospective observational study. We measured Cox, a surrogate measurement of cerebral blood flow, measured by near-infrared spectroscopy, which is an index of CA derived from the moving correlation between mean arterial pressure and slow waves of regional cerebral oxygen saturation. A COx value that approaches 1 indicates impaired CA. Using COx, we determined the optimal MAP (MAPOPT), lower and upper limits of autoregulation for individual patients. These measurements were examined in relation to modified Rankin Scale (mRS) scores.

Results

Fifteen patients (median age=57 years [IQR=47-69]) with 150 autoregulation measurements were included for analysis. Eleven were on veno-arterial ECMO and 4 on veno-venous. Mean COx was higher on post-cannulation day 1 than on day 2 (0.2 vs 0.09, p<0.01), indicating improved CA over time. COx was higher in VA-ECMO patients than in VV-ECMO (0.12 vs 0.06, p=0.04). Median MAPOPT for entire cohort was highly variable, ranging 55-110 mmHg. Patients with mRS 0-3 (good outcome) at 3 and 6 months spent less time outside of MAPOPT compared to patients with mRS 4-6 (poor outcome) (74% vs 82%, p=0.01). The percentage of time when observed MAP was outside the limits of autoregulation was higher on post-cannulation day 1 than on day 2 (18.2% vs 3.3%, p<0.01).

Conclusions

In ECMO patients, it is feasible to monitor CA continuously at the bedside. CA improved over time, most significantly between post-cannulation days 1 and 2. CA was more impaired in VA-ECMO than VV-ECMO. Spending less time outside of MAPOPT may be associated with achieving a good neurologic outcome.

Prediction of lactate concentrations after cardiac surgery using machine learning and deep learning approaches

Background

Although conventional prediction models for surgical patients often ignore intraoperative time-series data, deep learning approaches are well-suited to incorporate time-varying and non-linear data with complex interactions. Blood lactate concentration is one important clinical marker that can reflect the adequacy of systemic perfusion during cardiac surgery. During cardiac surgery and cardiopulmonary bypass, minute-level data is available on key parameters that affect perfusion. The goal of this study was to use machine learning and deep learning approaches to predict maximum blood lactate concentrations after cardiac surgery. We hypothesized that models using minute-level intraoperative data as inputs would have the best predictive performance.

Methods

Adults who underwent cardiac surgery with cardiopulmonary bypass were eligible. The primary outcome was maximum lactate concentration within 24 h postoperatively. We considered three classes of predictive models, using the performance metric of mean absolute error across testing folds: (1) static models using baseline preoperative variables, (2) augmentation of the static models with intraoperative statistics, and (3) a dynamic approach that integrates preoperative variables with intraoperative time series data.

Results

2,187 patients were included. For three models that only used baseline characteristics (linear regression, random forest, artificial neural network) to predict maximum postoperative lactate concentration, the prediction error ranged from a median of 2.52 mmol/L (IQR 2.46, 2.56) to 2.58 mmol/L (IQR 2.54, 2.60). The inclusion of intraoperative summary statistics (including intraoperative lactate concentration) improved model performance, with the prediction error ranging from a median of 2.09 mmol/L (IQR 2.04, 2.14) to 2.12 mmol/L (IQR 2.06, 2.16). For two modelling approaches (recurrent neural network, transformer) that can utilize intraoperative time-series data, the lowest prediction error was obtained with a range of median 1.96 mmol/L (IQR 1.87, 2.05) to 1.97 mmol/L (IQR 1.92, 2.05). Intraoperative lactate concentration was the most important predictive feature based on Shapley additive values. Anemia and weight were also important predictors, but there was heterogeneity in the importance of other features.

Conclusion

Postoperative lactate concentrations can be predicted using baseline and intraoperative data with moderate accuracy. These results reflect the value of intraoperative data in the prediction of clinically relevant outcomes to guide perioperative management.

Domains of Frailty Predict Loss of Independence in Older Adults After Noncardiac Surgery

IMPORTANCE

Preoperative frailty has been consistently associated with death, severe complications, and loss of independence (LOI) after surgery. LOI is an important patient-centered outcome, but it is unclear which domains of frailty are most strongly associated with LOI. Such information would be important to target individual geriatric domains for optimization.

OBJECTIVE

To assess whether impairment in individual domains of the Edmonton Frail Scale (EFS) can predict LOI in older adults after noncardiac surgery.

DESIGN

Retrospective Cohort Study.

SETTING

One Academic Hospital.

PARTICIPANTS

Patients aged 65 or older who were living independently and evaluated with the EFS during a preoperative visit to the Center for Preoperative Optimization at the Johns Hopkins Hospital between June 2018 and January 2020.

MAIN OUTCOME

LOI defined as discharge to increased level of care outside of the home with new mobility deficit or functional dependence. New mobility deficit and functional dependence were extracted from chart review of the standardized occupational therapy and physical therapy assessment performed before discharge.

RESULTS

A total of 3497 patients were analyzed. Age (mean±SD) was 73.4±6.2 years, and 1579 (45.2%) were female. The median total EFS score was 3 (range 0-16), and 725/3497 (27%) were considered frail (EFS≥6). The frequencies of impairment in each EFS domain were functional performance (33.5% moderately impaired, 11% severely impaired), history of hospital readmission (42%), poor self-described health status (37%), and abnormal cognition (17.1% moderately impaired, 13.8% severely impaired). Overall, 235/3497 (6.7%) patients experienced LOI. Total EFS score was associated with LOI (odds ratio: 1.37, 95% CI, 1.30-1.45, P <0.001) in a model adjusted for age, sex, body mass index, American Society of Anesthesiologists rating, congestive heart failure, valvular heart disease, hypertension diagnosis, chronic lung disease, diabetes, renal failure, liver disease, weight loss, anemia, and depression. Using a nested log likelihood approach, the domains of functional performance, functional dependence, social support, health status, and urinary incontinence improved the base multivariable model. In cross-validation, total EFS improved the prediction of LOI with the final model achieving an area under the curve of 0.840. Functional performance was the single domain that most improved outcome prediction, but together with functional dependence, social support, and urinary incontinence, the model resulted in an area under the curve of 0.838.

CONCLUSION AND RELEVANCE

Among domains measured by the EFS before a wide range of noncardiac surgeries in older adults, functional performance, functional dependence, social support, and urinary incontinence were independently associated with and improved the prediction of LOI. Clinical initiatives to mitigate LOI may consider screening with the EFS and targeting abnormalities within these domains.

Incidence of Dementia Following Hospitalization With Infection Among Adults in the Atherosclerosis Risk in Communities (ARIC) Study Cohort

Importance

Factors associated with the risk of dementia remain to be fully understood. Systemic infections are hypothesized to be such factors and may be targets for prevention and screening.

Objective

To investigate the association between hospitalization with infection and incident dementia.

Design, Setting, and Participants

Data from the community-based Atherosclerosis Risk in Communities (ARIC) study, a prospective cohort study, were used. Enrollment occurred at 4 research centers in the US, initiated in 1987 to 1989. The present study includes data up to 2019, for 32 years of follow-up. Data analysis was performed from April 2021 to June 2022.

Exposures

Hospitalizations with infections were identified via medical record review for selected International Classification of Diseases, Ninth Revision (ICD-9) and International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes, from baseline until administrative censoring or dementia diagnosis. Participants were considered unexposed until first hospitalization with infection and exposed thereafter. Selected infection subtypes were also considered.

Main Outcomes and Measures

Incident dementia and time-to-event data were identified through surveillance of ICD-9 and ICD-10 hospitalization and death certificate codes, in-person assessments, and telephone interviews. A sensitivity analysis was conducted excluding cases occurring within 3 years or beyond 20 years from exposure. Data were collected before study hypothesis formulation.

Results

Of the 15 792 ARIC study participants, an analytical cohort of 15 688 participants who were dementia free at baseline and of Black or White race were selected (8658 female [55.2%]; 4210 Black [26.8%]; mean [SD] baseline age, 54.7 [5.8] years). Hospitalization with infection occurred among 5999 participants (38.2%). Dementia was ascertained in 2975 participants (19.0%), at a median (IQR) of 25.1 (22.2-29.1) years after baseline. Dementia rates were 23.6 events per 1000 person-years (95% CI, 22.3-25.0 events per 1000 person-years) among the exposed and 5.7 events per 1000 person-years (95% CI, 5.4-6.0 events per 1000 person-years) among the unexposed. Patients hospitalized with infection were 2.02 (95% CI, 1.88-2.18; P < .001) and 1.70 (95% CI, 1.55-1.86; P < .001) times more likely to experience incident dementia according to unadjusted and fully adjusted Cox proportional hazards models compared with individuals who were unexposed. When excluding individuals who developed dementia less than 3 years or more than 20 years from baseline or the infection event, the adjusted hazard ratio was 5.77 (95% CI, 4.92-6.76; P < .001). Rates of dementia were significantly higher among those hospitalized with respiratory, urinary tract, skin, blood and circulatory system, or hospital acquired infections. Multiplicative and additive interactions were observed by age and APOE-ε genotype.

Conclusions and Relevance

Higher rates of dementia were observed among participants who experienced hospitalization with infection. These findings support the hypothesis that infections are factors associated with higher risk of dementias.

Comparing three wearable accelerometers to measure early activity after cardiac surgery

Objective

Wearable activity monitors can provide detailed data on activity after cardiac surgery and discriminate a patient's risk for hospital-based outcomes. However, comparative data for different monitoring approaches, as well as predictive ability over clinical characteristics, are lacking. In addition, data on specific thresholds of activity are needed. The objective of this study was to compare 3 wearable activity monitors and 1 observational mobility scale in discriminating risk for 3 hospital-based outcomes, and to establish clinically relevant step thresholds.

Methods

Cardiac surgery patients were enrolled between June 2016 and August 2017 in a cohort study. Postoperative activity was measured by 3 accelerometry monitors (StepWatch Ambulation Monitor, Fitbit Charge HR, and ActiGraph GT9X) and 1 nurse-based observation scale. Monitors represent a spectrum of characteristics, including wear location (ankle/wrist), output (activity counts/steps), consumer accessibility, and cost. Primary outcomes were duration of hospitalization >7 days, discharge to a nonhome location, and 30-day readmission.

Results

Data were available from 193 patients (median age 67 years [interquartile range, 58-72]). All postoperative day 2 activity metrics (ie, from StepWatch, Fitbit, ActiGraph, and the observation scale) were independently associated with prolonged hospitalization and discharge to a nonhome location. Only steps as measured by StepWatch was independently associated with 30-day readmission. Overall, StepWatch provided the greatest discrimination (C-statistics 0.71-0.76 for all outcomes). Step thresholds between 250 and 500 steps/day identified between 74% and 96% of patients with any primary outcome.

Conclusions

Data from wearable accelerometers provide additive value in early postoperative risk-stratification for hospital-based outcomes. These results both support and provide guidance for activity-monitoring programs after cardiac surgery.

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).

Five- and six-strand hamstring grafts consistently produce appropriate graft diameters for anterior cruciate ligament reconstruction

PURPOSE

Hamstring tendon graft diameter less than 8 mm has been correlated with an increased risk of anterior cruciate ligament reconstruction (ACLR) graft failure. The purpose of this study was to measure and compare the diameter of 3-, 4-, 5-, and 6-strand gracilis and semitendinosus (ST) hamstring tendon (HT) ACLR grafts, and to determine if there is a correlation between anthropometric data, HT length, and diameter of the HT ACLR graft.

METHODS

Male patients (n = 78) undergoing primary or revision ACLR with a HT autograft between July 2018 and March 2020 were recruited. Pre-operative anthropometric data was collected. Gracilis and ST tendons were harvested and the length and diameter measured. The following HT graft configurations were prepared in each patient: triple ST; double gracilis + double ST; double gracilis + triple ST; triple gracilis + triple ST. Paired t-tests and Pearson's correlation coefficients were used to assess demographics, anthropometrics, graft diameter, and tendon length. A non-parametric test was used to compare femoral and tibial ACL graft diameters of the 3-, 4-, 5-, and 6-strand HT graft configurations.

RESULTS

For the femoral end, 10%, 19%, 69% and 86% of the patients achieved graft diameters of equal to or greater than 8 mm in 3-, 4-, 5- and 6-strand HT graft configurations respectively. For the tibial end, 27%, 10%, 83%, and 92% of the patients achieved graft diameters of equal to or greater than 8 mm in 3-, 4-, 5-, and 6-strand HT graft configurations respectively. The largest increases in HT graft diameters were noted between the femoral end of 6- vs. 3-strand grafts (mean difference 1.7 ± 0.5 mm; p < 0.001) and between the tibial end of 6- vs. 4-strand grafts (mean difference 2.0 ± 0.5 mm; p < 0.001). Height and leg length were moderately positively correlated with ST tendon length (r = 0.54-0.51) and gracilis tendon length (r = 0.52-0.45), and thigh and shank lengths were moderately positively correlated with ST tendon length (r = 0.43 and 0.40, respectively).

CONCLUSION

Traditional 4-strand HT ACL autografts in male patients undergoing ACLR in the United Arab Emirates result in graft diameters less than 8 mm in the majority of patients.

LEVEL OF EVIDENCE

III.

Neurocognitive, Quality of Life, and Behavioral Outcomes for Patients With Covert Stroke After Cardiac Surgery: Exploratory Analysis of Data From a Prospectively Randomized Trial

BACKGROUND

Asymptomatic brain ischemic injury detected with diffusion-weighted magnetic resonance imaging (DWI) is reported in more than one-half of patients after cardiac surgery. There are conflicting findings on whether DWI-detected covert stroke is associated with neurocognitive dysfunction after surgery, and it is unclear whether such ischemic injury affects quality of life or behavioral outcomes. The purpose of this study was to perform exploratory analysis on whether covert stroke after cardiac surgery is associated with delayed neurocognitive recovery 1 month after surgery, impaired quality of life, anxiety, or depression.

METHODS

Analysis of data collected in a prospectively randomized study in patients undergoing cardiac surgery testing whether basing mean arterial pressure (MAP) targets during cardiopulmonary bypass to be above the lower limit of cerebral autoregulation versus usual practices reduces the frequency of adverse neurological outcomes. A neuropsychological testing battery was administered before surgery and then 1 month later. Patients underwent brain magnetic resonance imaging (MRI) between postoperative days 3 and 5. The primary outcome was DWI-detected ischemic lesion; the primary end point was change from baseline in domain-specific neurocognitive Z scores 1 month after surgery. Secondary outcomes included a composite indicator of delayed neurocognitive recovery, quality of life measures, state and trait anxiety, and Beck Depression Inventory scores.

RESULTS

Of the 164 patients with postoperative MRI data, clinical stroke occurred in 10 patients. Of the remaining 154 patients, 85 (55.2%) had a covert stroke. There were no statistically significant differences for patients with or without covert stroke in the change from baseline in Z scores in any of the cognitive domains tested adjusted for sex, baseline cognitive score, and randomization treatment arm. The frequency of delayed neurocognitive recovery (no covert stroke, 15.1%; covert stroke, 17.6%; P = .392), self-reported quality of life measurements, anxiety rating, or depression scores were not different between those with or without DWI ischemic injury.

CONCLUSIONS

More than one-half of patients undergoing cardiac surgery demonstrated covert stroke. In this exploratory analysis, covert stroke was not found to be significantly associated with neurocognitive dysfunction 1 month after surgery; evidence of impaired quality of life, anxiety, or depression, albeit a type II error, cannot be excluded.

The association of bispectral index values and metrics of cerebral perfusion during cardiopulmonary bypass

STUDY OBJECTIVE

Low bispectral index (BIS) values have been associated with adverse postoperative outcomes. However, trials of optimizing BIS by titrating anesthetic administration have reported conflicting results. One potential explanation is that cerebral perfusion may also affect BIS, but the extent of this relationship is not clear. Therefore, we examined whether BIS would be associated with cerebral perfusion during cardiopulmonary bypass, when anesthetic concentration was constant.

DESIGN

Observational cohort study.

SETTING

Cardiac operating room.

PATIENTS

Seventy-nine patients with cardiopulmonary bypass surgery were included.

MEASUREMENTS

Continuous BIS, mean arterial blood pressure (MAP), cerebral blood flow velocity (CBFV), and regional cerebral oxygen saturation (rSO₂) were monitored, with analysis during a period of constant anesthetic. Mean flow index (Mx) was calculated as Pearson correlation between MAP and CBFV. The lower limit of autoregulation (LLA) was identified as the MAP value at which Mx increased >0.4 with decreasing blood pressure. Postoperative delirium was assessed using the 3D-Confusion Assessment Method.

RESULTS

Mean BIS was lower during periods of MAP < LLA compared with BIS when MAP>LLA (mean 49.35 ± 10.40 vs. 50.72 ± 10.04, p = 0.002, mean difference = 1.38 [standard error: 0.42]). There was a dose response effect, with the BIS proportionately decreasing as MAP decreased below LLA (β = 0.15, 95% CI for the average slope across all patients 0.07 to 0.23, p < 0.001). In contrast, BIS was relatively unchanged when MAP was above LLA (β = 0.03, 95% CI for the average slope across all patients -0.02 to 0.09, p = 0.22). Additionally, increasing CBFV and rSO₂ were associated with increasing BIS. Patients with postoperative delirium had lower mean BIS and higher percentage of time duration with BIS <45 compared to patients without delirium.

CONCLUSIONS

There was an association of BIS and metrics of cerebral perfusion during a period of constant anesthetic administration, but the absolute magnitude of change in BIS as MAP decreased below the LLA was small.

Determining Thresholds for Three Indices of Autoregulation to Identify the Lower Limit of Autoregulation During Cardiac Surgery

OBJECTIVES

Monitoring cerebral autoregulation may help identify the lower limit of autoregulation in individual patients. Mean arterial blood pressure below lower limit of autoregulation appears to be a risk factor for postoperative acute kidney injury. Cerebral autoregulation can be monitored in real time using correlation approaches. However, the precise thresholds for different cerebral autoregulation indexes that identify the lower limit of autoregulation are unknown. We identified thresholds for intact autoregulation in patients during cardiopulmonary bypass surgery and examined the relevance of these thresholds to postoperative acute kidney injury.

DESIGN

A single-center retrospective analysis.

SETTING

Tertiary academic medical center.

PATIENTS

Data from 59 patients was used to determine precise cerebral autoregulation thresholds for identification of the lower limit of autoregulation. These thresholds were validated in a larger cohort of 226 patients.

METHODS AND MAIN RESULTS

Invasive mean arterial blood pressure, cerebral blood flow velocities, regional cortical oxygen saturation, and total hemoglobin were recorded simultaneously. Three cerebral autoregulation indices were calculated, including mean flow index, cerebral oximetry index, and hemoglobin volume index. Cerebral autoregulation curves for the three indices were plotted, and thresholds for each index were used to generate threshold- and index-specific lower limit of autoregulations. A reference lower limit of autoregulation could be identified in 59 patients by plotting cerebral blood flow velocity against mean arterial blood pressure to generate gold-standard Lassen curves. The lower limit of autoregulations defined at each threshold were compared with the gold-standard lower limit of autoregulation determined from Lassen curves. The results identified the following thresholds: mean flow index (0.45), cerebral oximetry index (0.35), and hemoglobin volume index (0.3). We then calculated the product of magnitude and duration of mean arterial blood pressure less than lower limit of autoregulation in a larger cohort of 226 patients. When using the lower limit of autoregulations identified by the optimal thresholds above, mean arterial blood pressure less than lower limit of autoregulation was greater in patients with acute kidney injury than in those without acute kidney injury.

CONCLUSIONS

This study identified thresholds of intact and impaired cerebral autoregulation for three indices and showed that mean arterial blood pressure below lower limit of autoregulation is a risk factor for acute kidney injury after cardiac surgery.

Retrograde Autologous Priming in Cardiac Surgery: Results From a Systematic Review and Meta-analysis

BACKGROUND

Retrograde autologous priming (RAP) before cardiopulmonary bypass (CPB) may minimize allogeneic red cell transfusion. We conducted a systematic review of the literature to examine the impact of RAP on perioperative allogeneic red cell transfusions in cardiac surgical patients.

METHODS

This study involved a systematic review and meta-analysis of randomized controlled trials (RCTs) and observational studies evaluating the use of RAP in cardiac surgery involving CPB. The primary outcome was intraoperative allogeneic red cell transfusion. Secondary outcomes included whole hospital allogeneic transfusions and adverse events such as acute kidney injury (AKI) and stroke.

RESULTS

A total of 11 RCTs (n = 1337 patients) were included, comparing RAP patients (n = 674) to control (n = 663). In addition, 10 observational studies (n = 2327) were included, comparing RAP patients (n = 1257) to control (n = 1070). Overall, RAP was associated with a significantly reduced incidence of intraoperative red cell transfusion (n = 18 studies; odds ratio [OR] = 0.34; 95% confidence interval [CI], 0.22-0.55, P < .001) compared to controls. This effect was seen among RCTs (n = 10 studies; OR = 0.19; 95% CI, 0.08-0.45, P < .001) and observational studies (n = 8 studies; OR = 0.66; 95% CI, 0.50-0.87, P = .004) in isolation. RAP was also associated with a significantly reduced incidence of whole hospital red cell transfusion (n = 5 studies; OR = 0.28; 95% CI, 0.19-0.41, P < .001). Among the studies that reported AKI and stroke outcomes, there was no statistically significant increased odds of AKI or stroke in either RAP or control patients.

CONCLUSIONS

Based on the pooled results of the available literature, RAP is associated with a significant reduction in intraoperative and whole hospital allogeneic red cell transfusion. Use of RAP may prevent hemodilution of cardiac surgical patients and thus, lessen transfusions. Additional high-quality prospective studies are necessary to determine the ideal priming volume necessary to confer the greatest benefit without incurring organ injury.

Spinal Anesthesia for Geriatric Lumbar Spine Surgery: A Comparative Case Series

BACKGROUND

The use of spinal anesthesia (SA) as opposed to general anesthesia (GA) during elective lumbar spine surgery is an emerging technique and represents a potentially modifiable factor to limit perioperative complications. Few studies, however, have compared these anesthetic techniques in an elderly population. The aim of this study is to determine if SA is a safe alternative to GA for lumbar spine surgery in elderly patients.

METHODS

A retrospective, consecutive case series study was performed. All patients aged 70 years and older who underwent lumbar spine decompression or combined decompression and fusion using either SA or GA during a 2-year period at a single institution were identified. Demographics and perioperative outcomes were compared.

RESULTS

Of all patients meeting the inclusion criteria, 56 patients (19%) received SA and 239 (81%) received GA. Patients receiving SA were slightly older (median age, 77 years versus 75 years, P = .002), consisted of more men (57% versus 36%, P = .01), and had a lower mean body mass index (28.3 versus 30.1, P = .03). Indications for surgery and type of surgery were similar between groups. On average, operative times with SA were 101 minutes versus 103 minutes with GA (P = .71). After controlling for age, sex, and body mass index, patients receiving SA had decreased estimated blood loss (β = -75 mL; 95% confidence interval [CI], -140.6, -9.4; P = .025) and intraoperative intravenous fluid requirements (β = -205 mL; 95% CI, -389.4, -21.0; P = .029), shorter postanesthesia care unit stays (β = -41 minutes; 95% CI, -64.6, -16.9; P = .001), lower maximum visual analog scale pain scores (β = -0.89 points; 95% CI, -1.6, -0.1; P = .020), and decreased odds of receiving blood transfusion (odds ratio, 0.12; 95% CI, 0.01, 0.62; P = .45); there were no significant differences in operative time, length of stay, nausea, or oral morphine equivalents consumed per day. Complication rates were similar between groups.

CONCLUSION

Spinal anesthesia is a reasonable, safe alternative to general anesthesia for lumbar spine surgery in elderly patients with degenerative conditions.

Effect of Targeting Mean Arterial Pressure During Cardiopulmonary Bypass by Monitoring Cerebral Autoregulation on Postsurgical Delirium Among Older Patients: A Nested Randomized Clinical Trial

Importance

Delirium occurs in up to 52% of patients after cardiac surgery and may result from changes in cerebral perfusion. Using intraoperative cerebral autoregulation monitoring to individualize and optimize cerebral perfusion may be a useful strategy to reduce the incidence of delirium after cardiac surgery.

Objective

To determine whether targeting mean arterial pressure during cardiopulmonary bypass (CPB) using cerebral autoregulation monitoring reduces the incidence of delirium compared with usual care.

Design, Setting, and Participants

This randomized clinical trial nested within a larger trial enrolled patients older than 55 years who underwent nonemergency cardiac surgery at a single US academic medical center between October 11, 2012, and May 10, 2016, and had a high risk for neurologic complications. Patients, physicians, and outcome assessors were masked to the assigned intervention. A total of 2764 patients were screened, and 199 were eligible for analysis in this study.

Intervention

In the intervention group, the patient's lower limit of cerebral autoregulation was identified during surgery before CPB. On CPB, the patient's mean arterial pressure was targeted to be greater than that patient's lower limit of autoregulation. In the control group, mean arterial pressure targets were determined according to institutional practice.

Main Outcomes and Measures

The main outcome was any incidence of delirium on postoperative days 1 through 4, as adjudicated by a consensus expert panel.

Results

Among the 199 participants in this study, mean (SD) age was 70.3 (7.5) years and 150 (75.4%) were male. One hundred sixty-two (81.4%) were white, 26 (13.1%) were black, and 11 (5.5%) were of other race. Of 103 patients randomized to usual care, 94 were analyzed, and of 102 patients randomized to the intervention 105 were analyzed. Excluding 5 patients with coma, delirium occurred in 48 of the 91 patients (53%) in the usual care group compared with 39 of the 103 patients (38%) in the intervention group (P = .04). The odds of delirium were reduced by 45% in patients randomized to the autoregulation group (odds ratio, 0.55; 95% CI, 0.31-0.97; P = .04).

Conclusions and Relevance

The results of this study suggest that optimizing mean arterial pressure to be greater than the individual patient's lower limit of cerebral autoregulation during CPB may reduce the incidence of delirium after cardiac surgery, but further study is needed.

Trial Registration

ClinicalTrials.gov identifier: NCT00981474.

Treatment After Anterior Cruciate Ligament Injury: Panther Symposium ACL Treatment Consensus Group

Treatment strategies for anterior cruciate ligament (ACL) injuries continue to evolve. Evidence supporting best-practice guidelines for the management of ACL injury is to a large extent based on studies with low-level evidence. An international consensus group of experts was convened to collaboratively advance toward consensus opinions regarding the best available evidence on operative versus nonoperative treatment for ACL injury. The purpose of this study was to report the consensus statements on operative versus nonoperative treatment of ACL injuries developed at the ACL Consensus Meeting Panther Symposium 2019. There were 66 international experts on the management of ACL injuries, representing 18 countries, who were convened and participated in a process based on the Delphi method of achieving consensus. Proposed consensus statements were drafted by the scientific organizing committee and session chairs for the 3 working groups. Panel participants reviewed preliminary statements before the meeting and provided initial agreement and comments on the statement via online survey. During the meeting, discussion and debate occurred for each statement, after which a final vote was then held. Ultimately, 80% agreement was defined a priori as consensus. A total of 11 of 13 statements on operative versus nonoperative treatment of ACL injury reached consensus during the symposium. Overall, 9 statements achieved unanimous support, 2 reached strong consensus, 1 did not achieve consensus, and 1 was removed because of redundancy in the information provided. In highly active patients engaged in jumping, cutting, and pivoting sports, early anatomic ACL reconstruction is recommended because of the high risk of secondary meniscal and cartilage injuries with delayed surgery, although a period of progressive rehabilitation to resolve impairments and improve neuromuscular function is recommended. For patients who seek to return to straight-plane activities, nonoperative treatment with structured, progressive rehabilitation is an acceptable treatment option. However, with persistent functional instability, or when episodes of giving way occur, anatomic ACL reconstruction is indicated. The consensus statements derived from international leaders in the field will assist clinicians in deciding between operative and nonoperative treatment with patients after an ACL injury.

Association of Surgical Hospitalization with Brain Amyloid Deposition: The Atherosclerosis Risk in Communities-Positron Emission Tomography (ARIC-PET) Study

BACKGROUND

As more older adults undergo surgery, it is critical to understand the long-term effects of surgery on brain health, particularly in relation to the development of Alzheimer's disease. This study examined the association of surgical hospitalization with subsequent brain β-amyloid deposition in nondemented older adults.

METHODS

The Atherosclerosis Risk in Communities-Positron Emission Tomography (ARIC-PET) study is a prospective cohort study of 346 participants without dementia who underwent florbetapir PET imaging. Active surveillance of local hospitals and annual participant contact were used to gather hospitalization and surgical information (International Classification of Disease, Ninth Revision, Clinical Modification codes) over the preceding 24-yr period. Brain amyloid measured using florbetapir PET imaging was the primary outcome. Elevated amyloid was defined as a standardized uptake value ratio of more than 1.2.

RESULTS

Of the 313 participants included in this analysis (age at PET: 76.0 [SD 5.4]; 56% female), 72% had a prior hospitalization, and 50% had a prior surgical hospitalization. Elevated amyloid occurred in 87 of 156 (56%) participants with previous surgical hospitalization, compared with 45 of 87 (52%) participants who had no previous hospitalization. Participants with previous surgical hospitalizations did not show an increased odds of elevated brain amyloid (odds ratio, 1.32; 95% CI, 0.72 to 2.40; P = 0.370) after adjusting for confounders (primary analysis). Results were similar using the reference group of all participants without previous surgery (hospitalized and nonhospitalized; odds ratio, 1.58; 95% CI, 0.96 to 2.58; P = 0.070). In a prespecified secondary analysis, participants with previous surgical hospitalization did demonstrate increased odds of elevated amyloid when compared with participants hospitalized without surgery (odds ratio, 2.10; 95% CI, 1.09 to 4.05; P = 0.026). However, these results were attenuated and nonsignificant when alternative thresholds for amyloid-positive status were used.

CONCLUSIONS

The results do not support an association between surgical hospitalization and elevated brain amyloid.

Anterior Cruciate Ligament Femoral Tunnel Placement: An Analysis of the Intended Versus Achieved Position for 221 International High-Volume ACL Surgeons

BACKGROUND

Femoral tunnels that are not anatomically placed within the native anterior cruciate ligament (ACL) footprint during ACL reconstruction are associated with residual instability, graft rupture, and poor clinical outcomes. Although surgeons may intend to place their femoral tunnels within the native ACL attachment, this is not always achieved. This study assesses the variation between intended and achieved femoral tunnel positions in a large cohort of experienced ACL surgeons.

HYPOTHESIS

The accuracy with which experienced ACL surgeons achieve their intended femoral tunnel position is dependent on viewing portal, localization strategy, and drilling technique.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 221 surgeons indicated their intended femoral tunnel location on a true lateral radiograph of a cadaveric knee specimen and a scaled photograph. Each surgeon then arthroscopically demonstrated the femoral tunnel on the specimen. The position was captured using fluoroscopy. The Euclidean distance (the straight-line distance between 2 points) between the intended and achieved tunnel positions, referenced to a grid applied to the lateral femoral condyle, was compared. Data were analyzed according to surgeons' viewing portal (anteromedial [AM] or anterolateral [AL]), tunnel localization strategy (offset aimer, estimation from landmarks, ACL ruler, or C-arm fluoroscopy), and stated drilling technique (transtibial, AM portal, or outside-in).

RESULTS

Surgeons who viewed the lateral intercondylar notch wall through the AM portal were closer (mean distance, 9.5) to their intended position than those who viewed through the AL portal (mean distance, 15.1; P < .0001). By localization strategy, the mean distance between achieved and intended tunnel positions was greater for surgeons who used an offset aimer (14.5) and estimated the femoral tunnel position (12.9) than for those using a malleable ACL ruler (8.1; P < .0001) and fluoroscopy (4.3; P < .0001). Surgeons' preferred drilling technique (AM portal, transtibial, or outside-in) had no effect on distance between intended and achieved positions. However, the mean achieved position was higher in the intercondylar notch for those using transtibial drilling (P < .042).

CONCLUSION

Surgeons using the AM portal to view the femoral attachment site were closer to their intended tunnel position than those who viewed it with the arthroscope in the AL portal. Surgeons who used fluoroscopy to localize femoral tunnel position were the closest to their intended position. Those who used estimation or an offset aimer had the farthest distance between achieved and intended tunnel positions.

CLINICAL RELEVANCE

Although accurate tunnel placement can be achieved using any method, given the disparity between intended and achieved tunnel positions, it may be advisable, even for high-volume surgeons, to verify the placement of their tunnels using either fluoroscopy or a malleable ACL ruler to ensure that they achieve their intended position. Fluoroscopy may be particularly useful for cases where the native femoral stump is no longer visible and for revisions. Viewing through the AM portal is recommended to aid accuracy of tunnel placement.

Observational Study Examining the Association of Baseline Frailty and Postcardiac Surgery Delirium and Cognitive Change

BACKGROUND

Frailty is a geriatric syndrome thought to identify the most vulnerable older adults, and morbidity and mortality has been reported to be higher for frail patients after cardiac surgery compared to nonfrail patients. However, the cognitive consequences of frailty after cardiac surgery have not been well described. In this study, we examined the hypothesis that baseline frailty would be associated with postoperative delirium and cognitive change at 1 and 12 months after cardiac surgery.

METHODS

This study was nested in 2 trials, each of which was conducted by the same research team with identical measurement of exposures and outcomes. Before surgery, patients were assessed with the validated "Fried" frailty scale, which evaluates 5 domains (shrinking, weakness, exhaustion, low physical activity, and slowed walking speed) and classifies patients as nonfrail, prefrail, and frail. The primary outcome was postoperative delirium during hospitalization, which was assessed using the Confusion Assessment Method, Confusion Assessment Method for the Intensive Care Unit, and validated chart review. Neuropsychological testing was a secondary outcome and was generally performed within 2 weeks of surgery and then 4-6 weeks and 1 year after surgery, and the outcome of interest was change in composite Z-score of the test battery. Associations were analyzed using logistic and linear regression models, with adjustment for variables considered a priori (age, gender, race, education, and logistic European System for Cardiac Operative Risk Evaluation). Multiple imputation was used to account for missing data at the 12-month follow-up.

RESULTS

Data were available from 133 patients with baseline frailty assessments. Compared to nonfrail patients (13% delirium incidence), the incidence of delirium was higher in prefrail (48% delirium incidence; risk difference, 35%; 95% CI, 10%-51%) and frail patients (48% delirium incidence; risk difference, 35%; 95% CI, 7%-53%). In both univariable and multivariable models, the odds of delirium were significantly higher for prefrail (adjusted odds ratio, 6.43; 95% CI, 1.31-31.64; P = .02) and frail patients (adjusted odds ratio, 6.31; 95% CI, 1.18-33.74; P = .03) compared to nonfrail patients. The adjusted decline in composite cognitive Z-score was greater from baseline to 1 month only in frail patients compared to nonfrail patients. By 1 year after surgery, there were no differences in the association of baseline frailty with change in cognition.

CONCLUSIONS

Compared to nonfrail patients, both prefrail and frail patients were at higher risk for the primary outcome of delirium after cardiac surgery. Frail patients were also at higher risk for the secondary outcome of greater decline in cognition from baseline to 1 month, but not baseline to 1 year, after surgery.

Discharge Hemoglobin Level and 30-Day Readmission Rates After Coronary Artery Bypass Surgery

BACKGROUND

Restrictive transfusion strategies supported by large randomized trials are resulting in decreased blood utilization in cardiac surgery. What remains to be determined, however, is the impact of lower discharge hemoglobin (Hb) levels on readmission rates. We assessed patients with higher versus lower Hb levels on discharge to compare 30-day readmission rates after coronary artery bypass grafting (CABG).

METHODS

We retrospectively evaluated 1552 patients undergoing isolated CABG at our institution from January 2013 to May 2016. We evaluated 2 Hb cohorts: "high" (above) and "low" (below) the mean discharge Hb level of 9.4 g/dL, comparing patient characteristics, blood utilization, and clinical outcomes including 30-day readmission rates. We further evaluated the effects of the lowest (<8 g/dL) discharge Hb levels on 30-day readmission rates by dividing the patients into 4 anemia cohorts based on discharge Hb levels: "no anemia" (>12 g/dL), "mild anemia" (10-11.9 g/dL), "moderate anemia" (8-9.9 g/dL), and "severe anemia" (<8 g/dL). Risk adjustment accounted for age, sex, Charlson comorbidity index, preoperative comorbidities, revision sternotomy, and patient blood management program implementation.

RESULTS

The "high" and "low" groups had similar patient characteristics except for Hb levels (mean discharge Hb was 10.4 ± 0.9 vs 8.5 ± 0.6 g/dL, respectively). Notably, no evidence for a difference in 30-day readmission rates was noted between the "high" (76/746; 10.2%) and "low" (97/806; 12.0%) (P = .25) Hb cohorts. The 4 anemia cohorts had differences in age, revision sternotomy incidence, Hb levels, certain patient comorbidities, and time to readmission. On multivariable analysis, the risk-adjusted odds of readmission in the "low" Hb cohort (odds ratio, 1.16; 95% confidence interval, 0.84-1.61; P = .36) was not significant compared to the "high" Hb cohort. Compared to patients with discharge Hb ≥8 g/dL, patients with Hb <8 g/dL had a higher incidence of readmission (22/129; 17.1% vs 151/1423; 10.6%; P = .036). On multivariable analysis, Hb <8 g/dL on discharge was predictive of readmission (odds ratio, 1.77; 95% confidence interval, 1.05-2.88; P = .03). The most common reason for readmission was volume overload, followed by infection and arrhythmias.

CONCLUSIONS

A discharge Hb level below the institution mean for CABG patients does not provide evidence for an association with an increased 30-day readmission rate. In the small number of patients discharged with Hb <8 g/dL, there is a suggestion of increased risk for readmission and larger more controlled studies are needed to verify or refute this finding.

Lengthy complex lumbar fusion surgery in high-risk elderly patient under spinal anesthesia: A case report

•

The longest reported lumbar surgery in an elderly patient under spinal anesthesia.

•

Spinal Anesthesia is a feasible option for lengthy geriatric lumbar surgery.

•

SA affords effective anesthesia with possibly lower physiological stress to some older patients.

•

Spinal Anesthesia may have elongated efficacy in the elderly population.

Introduction

Spinal Anesthesia (SA) continues to be an emerging technique for lumbar fusion surgery in the elderly population. SA is an appealing option in the high-risk geriatric population for several reasons, including the potential for reduced systematic stress, reduced blood loss, and reduced post-operative delirium. The safe limits of spine surgery under SA remain undetermined.

Presentation of case

The following case-study describes an elderly high-risk patient (ASA III) with severe spinal stenosis and degenerative scoliosis who presented with lower back and right leg pain and underwent a 3-level lumbar fusion surgery with spinal anesthesia. The procedure lasted 3 h and 44 min with sufficient anesthesia maintained throughout. The patient experienced minor post-operative complications, but had an excellent clinical outcome at 3-month follow-up.

Discussion

Further research should be conducted to define the temporal limits of SA in elderly patients and the etiology of post-operative complications following lumbar fusion surgery under spinal anesthesia in the geriatric population.

Conclusion

The case reported, herein, demonstrates the feasibility of SA in elderly patients undergoing lengthy complex lumbar surgeries who have been designated “high-risk” patients (ASA > II) and provides support for future investigation into surgical and anesthesia treatment options for geriatric high-risk patients presenting with complex lumbar spine pathologies.

Shaping anesthetic techniques to reduce post-operative delirium (SHARP) study: a protocol for a prospective pragmatic randomized controlled trial to evaluate spinal anesthesia with targeted sedation compared with general anesthesia in older adults undergoing lumbar spine fusion surgery

BACKGROUND

Postoperative delirium is common in older adults, especially in those patients undergoing spine surgery, in whom it is estimated to occur in > 30% of patients. Although previously thought to be transient, it is now recognized that delirium is associated with both short- and long-term complications. Optimizing the depth of anesthesia may represent a modifiable strategy for delirium prevention. However, previous studies have generally not focused on reducing the depth of anesthesia beyond levels consistent with general anesthesia. Additionally, the results of prior studies have been conflicting. The primary aim of this study is to determine whether reduced depth of anesthesia using spinal anesthesia reduces the incidence of delirium after lumbar fusion surgery compared with general anesthesia.

METHODS

This single-center randomized controlled trial is enrolling 218 older adults undergoing lumbar fusion surgery. Patients are randomized to reduced depth of anesthesia in the context of spinal anesthesia with targeted sedation using processed electroencephalogram monitoring versus general anesthesia without processed electroencephalogram monitoring. All patients are evaluated for delirium using the Confusion Assessment Method for 3 days after surgery or until discharge and undergo assessments of cognition, function, health-related quality of life, and pain at 3- and 12-months after surgery. The primary outcome is any occurrence of delirium. The main secondary outcome is change in the Mini-Mental Status Examination (or telephone equivalent) at 3-months after surgery.

DISCUSSION

Delirium is an important complication after surgery in older adults. The results of this study will examine whether reduced depth of anesthesia using spinal anesthesia with targeted depth of sedation represents a modifiable intervention to reduce the incidence of delirium and other long-term outcomes. The results of this study will be presented at national meetings and published in peer-reviewed journals with the goal of improving perioperative outcomes for older adults.

TRIAL REGISTRATION

Clinicaltrials.gov , NCT03133845. This study was submitted to Clinicaltrials.gov on October 23, 2015; however, it was not formally registered until April 28, 2017 due to formatting requirements from the registry, so the formal registration is retrospective.

Effect of Targeting Mean Arterial Pressure During Cardiopulmonary Bypass by Monitoring Cerebral Autoregulation on Postsurgical Delirium Among Older Patients: A Nested Randomized Clinical Trial

Importance

Delirium occurs in up to 52% of patients after cardiac surgery and may result from changes in cerebral perfusion. Using intraoperative cerebral autoregulation monitoring to individualize and optimize cerebral perfusion may be a useful strategy to reduce the incidence of delirium after cardiac surgery.

Objective

To determine whether targeting mean arterial pressure during cardiopulmonary bypass (CPB) using cerebral autoregulation monitoring reduces the incidence of delirium compared with usual care.

Design, Setting, and Participants

This randomized clinical trial nested within a larger trial enrolled patients older than 55 years who underwent nonemergency cardiac surgery at a single US academic medical center between October 11, 2012, and May 10, 2016, and had a high risk for neurologic complications. Patients, physicians, and outcome assessors were masked to the assigned intervention. A total of 2764 patients were screened, and 199 were eligible for analysis in this study.

Intervention

In the intervention group, the patient's lower limit of cerebral autoregulation was identified during surgery before CPB. On CPB, the patient's mean arterial pressure was targeted to be greater than that patient's lower limit of autoregulation. In the control group, mean arterial pressure targets were determined according to institutional practice.

Main Outcomes and Measures

The main outcome was any incidence of delirium on postoperative days 1 through 4, as adjudicated by a consensus expert panel.

Results

Among the 199 participants in this study, mean (SD) age was 70.3 (7.5) years and 150 (75.4%) were male. One hundred sixty-two (81.4%) were white, 26 (13.1%) were black, and 11 (5.5%) were of other race. Of 103 patients randomized to usual care, 94 were analyzed, and of 102 patients randomized to the intervention 105 were analyzed. Excluding 5 patients with coma, delirium occurred in 48 of the 91 patients (53%) in the usual care group compared with 39 of the 103 patients (38%) in the intervention group (P = .04). The odds of delirium were reduced by 45% in patients randomized to the autoregulation group (odds ratio, 0.55; 95% CI, 0.31-0.97; P = .04).

Conclusions and Relevance

The results of this study suggest that optimizing mean arterial pressure to be greater than the individual patient's lower limit of cerebral autoregulation during CPB may reduce the incidence of delirium after cardiac surgery, but further study is needed.

Trial Registration

ClinicalTrials.gov identifier: NCT00981474.

Use of an expert panel to identify domains and indicators of delirium severity

PURPOSE

Our purpose was to create a content domain framework for delirium severity to inform item development for a new instrument to measure delirium severity.

METHODS

We used an established, multi-stage instrument development process during which expert panelists discussed best approaches to measure delirium severity and identified related content domains. We conducted this work as part of the Better ASsessment of ILlness (BASIL) study, a prospective, observational study aimed at developing and testing measures of delirium severity. Our interdisciplinary expert panel consisted of twelve national delirium experts and four expert members of the core research group. Over a one-month period, experts participated in two rounds of review.

RESULTS

Experts recommended that the construct of delirium severity should reflect both the phenomena and the impact of delirium to create an accurate, patient-centered instrument useful to interdisciplinary clinicians and family caregivers. Final content domains were Cognitive, Level of consciousness, Inattention, Psychiatric-Behavioral, Emotional dysregulation, Psychomotor features, and Functional. Themes debated by experts included reconciling clinical geriatrics and psychiatric content, mapping symptoms to one specific domain, and accurate capture of unclear clinical presentations.

CONCLUSIONS

We believe this work represents the first application of instrument development science to delirium. The identified content domains are inclusive of various, wide-ranging domains of delirium severity and are reflective of a consistent framework that relates delirium severity to potential clinical outcomes. Our content domain framework provides a foundation for development of delirium severity instruments that can help improve care and quality of life for patients with delirium.

Cerebral Autoregulation-Guided Optimal Blood Pressure in Sepsis-Associated Encephalopathy: A Case Series

BACKGROUND

Impaired cerebral autoregulation and cerebral hypoperfusion may play a critical role in the high morbidity and mortality in patients with sepsis-associated encephalopathy (SAE). Bedside assessment of cerebral autoregulation may help individualize hemodynamic targets that optimize brain perfusion. We hypothesize that near-infrared spectroscopy (NIRS)-derived cerebral oximetry can identify blood pressure ranges that enhance autoregulation in patients with SAE and that disturbances in autoregulation are associated with severity of encephalopathy.

METHODS

Adult patients with acute encephalopathy directly attributable to sepsis were followed using NIRS-based multimodal monitoring for 12 consecutive hours. We used the correlation in time between regional cerebral oxygen saturation and mean arterial pressure (MAP) to determine the cerebral oximetry index (COx) as a measure of cerebral autoregulation. Autoregulation curves were constructed for each patient with averaged COx values sorted by MAP in 3 sequential 4-hour periods; the optimal pressure (MAP_OPT), defined as the MAP associated with most robust autoregulation (lowest COx), was identified in each period. Severity of encephalopathy was measured with Glasgow coma scale (GCS).

RESULTS

Six patients with extracranial sepsis met the stringent criteria specified, including no pharmacological sedation or neurologic premorbidity. Optimal MAP was identified in all patients and ranged from 55 to 115 mmHg. Additionally, MAP_OPT varied within individual patients over time during monitoring. Disturbed autoregulation, based on COx, was associated with worse neurologic status (GCS < 13) both with and without controlling for age and severity of sepsis (adjusted odds ratio [OR]: 2.11; 95% confidence interval [CI]: 1.77-2.52; P < .001; OR: 2.97; 95% CI: 1.63-5.43; P < .001).

CONCLUSIONS

In this high-fidelity group of patients with SAE, continuous, NIRS-based monitoring can identify blood pressure ranges that improve autoregulation. This is important given the association between cerebral autoregulatory function and severity of encephalopathy. Individualizing blood pressure goals using bedside autoregulation monitoring may better preserve cerebral perfusion in SAE than current practice.

Association of intraoperative changes in brain-derived neurotrophic factor and postoperative delirium in older adults

Background

Delirium is common after surgery, although the aetiology is poorly defined. Brain-derived neurotrophic factor (BDNF) is a neurotrophin important in neurotransmission and neuroplasticity. Decreased levels of BDNF have been associated with poor cognitive outcomes, but few studies have characterized the role of BDNF perioperatively. We hypothesized that intraoperative decreases in BDNF levels are associated with postoperative delirium.

Methods

Patients undergoing spine surgery were enrolled in a prospective cohort study. Plasma BDNF was collected at baseline and at least hourly intraoperatively. Delirium was assessed using rigorous methods, including the Confusion Assessment Method (CAM) and CAM for the intensive care unit. Associations of changes in BDNF and delirium were examined using regression models.

Results

Postoperative delirium developed in 32 of 77 (42%) patients. The median baseline BDNF level was 7.6 ng ml -1 [interquartile range (IQR) 3.0-11.2] and generally declined intraoperatively [median decline 61% (IQR 31-80)]. There was no difference in baseline BDNF levels by delirium status. However, the percent decline in BDNF was greater in patients who developed delirium [median 74% (IQR 51-82)] vs in those who did not develop delirium [median 50% (IQR 14-79); P =0.03]. Each 1% decline in BDNF was associated with increased odds of delirium in unadjusted {odds ratio [OR] 1.02 [95% confidence interval (CI) 1.00-1.04]; P =0.01}, multivariable-adjusted [OR 1.02 (95% CI 1.00-1.03); P =0.03], and propensity score-adjusted models [OR 1.02 (95% CI 1.00-1.04); P =0.03].

Conclusions

We observed an association between intraoperative decline in plasma BDNF and delirium. These preliminary results need to be confirmed but suggest that plasma BDNF levels may be a biomarker for postoperative delirium.

Best Practices for Postoperative Brain Health: Recommendations From the Fifth International Perioperative Neurotoxicity Working Group

As part of the American Society of Anesthesiology Brain Health Initiative goal of improving perioperative brain health for older patients, over 30 experts met at the fifth International Perioperative Neurotoxicity Workshop in San Francisco, CA, in May 2016, to discuss best practices for optimizing perioperative brain health in older adults (ie, >65 years of age). The objective of this workshop was to discuss and develop consensus solutions to improve patient management and outcomes and to discuss what older adults should be told (and by whom) about postoperative brain health risks. Thus, the workshop was provider and patient oriented as well as solution focused rather than etiology focused. For those areas in which we determined that there were limited evidence-based recommendations, we identified knowledge gaps and the types of scientific knowledge and investigations needed to direct future best practice. Because concerns about perioperative neurocognitive injury in pediatric patients are already being addressed by the SmartTots initiative, our workshop discussion (and thus this article) focuses specifically on perioperative cognition in older adults. The 2 main perioperative cognitive disorders that have been studied to date are postoperative delirium and cognitive dysfunction. Postoperative delirium is a syndrome of fluctuating changes in attention and level of consciousness that occurs in 20%-40% of patients >60 years of age after major surgery and inpatient hospitalization. Many older surgical patients also develop postoperative cognitive deficits that typically last for weeks to months, thus referred to as postoperative cognitive dysfunction. Because of the heterogeneity of different tools and thresholds used to assess and define these disorders at varying points in time after anesthesia and surgery, a recent article has proposed a new recommended nomenclature for these perioperative neurocognitive disorders. Our discussion about this topic was organized around 4 key issues: preprocedure consent, preoperative cognitive assessment, intraoperative management, and postoperative follow-up. These 4 issues also form the structure of this document. Multiple viewpoints were presented by participants and discussed at this in-person meeting, and the overall group consensus from these discussions was then drafted by a smaller writing group (the 6 primary authors of this article) into this manuscript. Of course, further studies have appeared since the workshop, which the writing group has incorporated where appropriate. All participants from this in-person meeting then had the opportunity to review, edit, and approve this final manuscript; 1 participant did not approve the final manuscript and asked for his/her name to be removed.

Association of Hospitalization, Critical Illness, and Infection with Brain Structure in Older Adults

OBJECTIVES

To examine the association between hospitalization, critical illness, and infection occurring during middle- and late-life and structural brain abnormalities in older adults.

DESIGN

Prospective cohort study.

SETTING

Atherosclerosis Risk in Communities (ARIC) Study.

PARTICIPANTS

A community sample of adults who were 44 to 66 years of age at study baseline.

MEASUREMENTS

Active surveillance of local hospitals and annual participant contact were used to gather hospitalization information (including International Classification of Diseases, Ninth Revision, codes) on all participants over a 24-year surveillance period. Subsequently, a subset of participants underwent 3-Tesla brain magnetic resonance imaging (MRI) to quantify total and regional brain volumes, white matter hyperintensity (WMH) volume, and white matter microstructural integrity (fractional anisotropy (FA) and mean diffusivity (MD) as measured using diffusion tensor imaging (DTI)).

RESULTS

Of the 1,689 participants included (mean age at MRI 76±5), 72% were hospitalized, 14% had a major infection, and 4% had a critical illness during the surveillance period. Using covariate-adjusted regression, hospitalization was associated with 0.12-standard deviation (SD) greater WMH volume (95% confidence interval (CI)=0.00-0.24) and poorer white matter microstructural integrity (0.17-SD lower FA, 95% CI=-0.27 to -0.06; 0.16-SD greater MD, 95% CI=0.07-0.25) than no hospitalization. There was a dose-dependent relationship between number of hospitalizations, smaller brain volumes, and lower white matter integrity (p-trends ≤.048). In hospitalized participants, critical illness was associated with smaller Alzheimer's disease (AD) signature region (-1.64 cm³ , 95% CI=-3.16 to -0.12); major infection was associated with smaller AD signature region (-1.28 cm³ , 95% CI=-2.21 to -0.35) and larger ventricular volume (3.79 cm³ , 95% CI= 0.81-6.77).

CONCLUSIONS

Whereas all-cause hospitalization was primarily associated with lower white matter integrity, critical illness and major infection were associated with smaller brain volume, particularly within regions implicated in AD.

Cognitive Decline after Delirium in Patients Undergoing Cardiac Surgery

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

Cardiac surgery is associated with cognitive decline and postoperative delirium. The relationship between postoperative delirium and cognitive decline after cardiac surgery is unclear

WHAT THIS ARTICLE TELLS US THAT IS NEW

The development of postoperative delirium is associated with a greater degree of cognitive decline 1 month after cardiac surgery. The development of postoperative delirium is not a predictor of cognitive decline 1 yr after cardiac surgery.

BACKGROUND

Delirium is common after cardiac surgery and has been associated with morbidity, mortality, and cognitive decline. However, there are conflicting reports on the magnitude, trajectory, and domains of cognitive change that might be affected. The authors hypothesized that patients with delirium would experience greater cognitive decline at 1 month and 1 yr after cardiac surgery compared to those without delirium.

METHODS

Patients who underwent coronary artery bypass and/or valve surgery with cardiopulmonary bypass were eligible for this cohort study. Delirium was assessed with the Confusion Assessment Method. A neuropsychologic battery was administered before surgery, at 1 month, and at 1 yr later. Linear regression was used to examine the association between delirium and change in composite cognitive Z score from baseline to 1 month (primary outcome). Secondary outcomes were domain-specific changes at 1 month and composite and domain-specific changes at 1 yr.

RESULTS

The incidence of delirium in 142 patients was 53.5%. Patients with delirium had greater decline in composite cognitive Z score at 1 month (greater decline by -0.29; 95% CI, -0.54 to -0.05; P = 0.020) and in the domains of visuoconstruction and processing speed. From baseline to 1 yr, there was no difference between delirious and nondelirious patients with respect to change in composite cognitive Z score, although greater decline in processing speed persisted among the delirious patients.

CONCLUSIONS

Patients who developed delirium had greater decline in a composite measure of cognition and in visuoconstruction and processing speed domains at 1 month. The differences in cognitive change by delirium were not significant at 1 yr, with the exception of processing speed.

Editorial Commentary: How to Increase Hamstring Tendon Graft Size for Anterior Cruciate Ligament Reconstruction

The concept of a five-strand hamstring tendon autograft for anterior cruciate ligament reconstruction is not new. The concept of a five-strand hamstring tendon autograft was largely ignored until recent studies showed higher failure and revision rates for hamstring ACL reconstructions performed with graft diameters less than 8 mm. In the majority of patients in the United Arab Emirates, four-strand hamstring tendon autografts result in a graft diameter between 6.5-7.5 mm. As a result, since 2006, I have completely abandoned using four-strand hamstring tendon autografts in favor of five-and six-stranded hamstring tendon autografts for ACL reconstructions. The key to performing five-or six-strand hamstring tendon autografts lies in the ability to triple the semitendinosus tendon and in the case of six-strand hamstring tendon grafts, the gracilis tendon. Although, five-and six-strand hamstring tendon autografts can increase the diameter of hamstring tendon ACL grafts, the question of whether these grafts will reduce failure and revision rates remains unanswered.

Incidence, Risk Factors, and Sequelae of Post-kidney Transplant Delirium

Background Frail kidney transplant (KT) recipients may be particularly vulnerable to surgical stressors, resulting in delirium and subsequent adverse outcomes. We sought to identify the incidence, risk factors, and sequelae of post-KT delirium.Methods We studied 125,304 adult KT recipients (1999-2014) to estimate delirium incidence in national registry claims. Additionally, we used a validated chart abstraction algorithm to identify post-KT delirium in 893 adult recipients (2009-2017) from a cohort study of frailty. Delirium sequelae were identified using adjusted logistic regression (length of stay ≥2 weeks and institutional discharge [skilled nursing or rehabilitation facility]) and adjusted Cox regression (death-censored graft loss and mortality).Results Only 0.8% of KT recipients had a delirium claim. In the cohort study, delirium incidence increased with age (18-49 years old: 2.0%; 50-64 years old: 4.6%; 65-75 years old: 9.2%; and ≥75 years old: 13.8%) and frailty (9.0% versus 3.9%); 20.0% of frail recipients aged ≥75 years old experienced delirium. Frailty was independently associated with delirium (odds ratio [OR], 2.05; 95% confidence interval [95% CI], 1.02 to 4.13; P=0.04), but premorbid global cognitive function was not. Recipients with delirium had increased risks of ≥2-week length of stay (OR, 5.42; 95% CI, 2.76 to 10.66; P<0.001), institutional discharge (OR, 22.41; 95% CI, 7.85 to 63.98; P<0.001), graft loss (hazard ratio [HR], 2.73; 95% CI, 1.14 to 6.53; P=0.03), and mortality (HR, 3.12; 95% CI, 1.76 to 5.54; P<0.001).Conclusions Post-KT delirium is a strong risk factor for subsequent adverse outcomes, yet it is a clinical entity that is often missed.

The Association of Mid- and Late-Life Systemic Inflammation with Brain Amyloid Deposition: The ARIC-PET Study

BACKGROUND

Although inflammation has been implicated in the pathogenesis of Alzheimer's disease, the effects of systemic inflammation on brain amyloid deposition remain unclear.

OBJECTIVE

We examined the association of midlife and late-life systemic inflammation with late-life brain amyloid levels in a community sample of non-demented older adults from the Atherosclerosis Risk in Communities (ARIC) - PET Study.

METHODS

339 non-demented participants (age: 75 [SD 5]) were recruited from the ARIC Study to undergo florbetapir PET (amyloid) imaging. Blood levels of high sensitivity C-reactive protein (CRP), a marker of systemic inflammation, were measured 22 years (Visit 2), 16 years (Visit 4), and up to 2 years before PET imaging (Visit 5). Elevated brain amyloid deposition (standardized uptake value ratio >1.2) was the primary outcome.

RESULTS

Our primary analyses found no association of midlife and late-life CRP with late-life brain amyloid levels. However, in secondary stratified analyses, we found that higher midlife (Visit 2) CRP was associated with elevated amyloid among males (OR 1.65, 95% CI: 1.13-2.42), and among white (OR 1.33, 95% CI: 1.02-1.75), but not African American, participants (p-interactions<0.05). Among male participants, those who maintained high CRP levels (≥3 mg/L) throughout mid- and late-life were most likely to have elevated brain amyloid (OR, 8.81; 95% CI: 1.23, 62.91).

CONCLUSIONS

Although our primary analysis does not support an association between systemic inflammation and brain amyloid deposition, we found evidence for sex- and race-dependent associations. However, findings from subgroup analyses should be interpreted with caution.

Blood utilization in revision versus first-time cardiac surgery: an update in the era of patient blood management

BACKGROUND

Relative to first-time (primary) cardiac surgery, revision cardiac surgery is associated with increased transfusion requirements, but studies comparing these cohorts were performed before patient blood management (PBM) and blood conservation measures were commonplace. The current study was performed as an update to determine if this finding is still evident in the PBM era.

STUDY DESIGN AND METHODS

Primary and revision cardiac surgery cases were compared in a retrospective database analysis at a single tertiary care referral center. Two groups of patients were assessed: 1) those having isolated coronary artery bypass (CAB) or valve surgery and 2) all other cardiac surgeries. Intraoperative and whole hospital transfusion requirements were assessed for the four major blood components.

RESULTS

Compared to the primary cardiac surgery patients, the revision surgery patients required approximately twofold more transfused units intraoperatively (p < 0.0001) and approximately two- to threefold more transfused units for the whole hospital stay (p < 0.0001). Intraoperative massive transfusion (>10 red blood cell [RBC] units) was substantially more frequent with revision versus primary cardiac surgery (2.6% vs. 0.1% [p < 0.0001] for isolated CAB or valve and 6.1% vs. 1.9% [p < 0.0001] for all other cardiac surgeries). Revision surgery was an independent risk factor for both moderate (6-10 RBC units) and massive intraoperative transfusion.

CONCLUSIONS

In the era of PBM, with restrictive transfusion strategies and a variety of methods for blood conservation, revision cardiac surgery patients continue to have substantially greater transfusion requirements relative to primary cardiac surgery patients. This difference in transfusion requirement was greater than what has been previously reported in the pre-PBM era.