Early automated cerebral edema assessment following endovascular therapy: impact on stroke outcome

BACKGROUND

Cerebral edema (CED) is associated with poorer outcome in patients with acute ischemic stroke (AIS). The aim of the study was to investigate the factors contributing to greater early CED formation in patients with AIS who underwent endovascular therapy (EVT) and its association with functional outcome.

METHODS

We conducted a multicenter cohort study of patients with an anterior circulation AIS undergoing EVT. The volume of cerebrospinal fluid (CSF) was extracted from baseline and 24-hour follow-up CT using an automated algorithm. The severity of CED was quantified by the percentage reduction in CSF volume between CT scans (∆CSF). The primary endpoint was a shift towards an unfavorable outcome, assessed by modified Rankin Scale (mRS) score at 3 months. Multivariable ordinal logistic regression analyses were performed. The ∆CSF threshold that predicted unfavorable outcome was selected using receiver operating characteristic curve analysis.

RESULTS

We analyzed 201 patients (mean age 72.7 years, 47.8% women) in whom CED was assessable for 85.6%. Higher systolic blood pressure during EVT and failure to achieve modified Thrombolysis In Cerebral Infarction (mTICI) 3 were found to be independent predictors of greater CED. ∆CSF was independently associated with the probability of a one-point worsening in the mRS score (common odds ratio (cOR) 1.05, 95% CI 1.03 to 1.08) after adjusting for age, baseline mRS, National Institutes of Health Stroke Scale (NIHSS), and number of passes. Displacement of more than 25% of CSF was associated with an unfavorable outcome (OR 6.09, 95% CI 3.01 to 12.33) and mortality (OR 6.72, 95% CI 2.94 to 15.32).

CONCLUSIONS

Early CED formation in patients undergoing EVT was affected by higher blood pressure and incomplete reperfusion. The extent of early CED, measured by automated ∆CSF, was associated with worse outcomes.

A Recruitment Maneuver After Apnea Testing Improves Oxygenation and Reduces Atelectasis in Organ Donors After Brain Death

BACKGROUND

Hypoxemia is the main modifiable factor preventing lungs from being transplanted from organ donors after brain death. One major contributor to impaired oxygenation in patients with brain injury is atelectasis. Apnea testing, an integral component of brain death declaration, promotes atelectasis and can worsen hypoxemia. In this study, we tested whether performing a recruitment maneuver (RM) after apnea testing could mitigate hypoxemia and atelectasis.

METHODS

During the study period, an RM (positive end-expiratory pressure of 15 cm H2O for 15 s then 30 cm H2O for 30 s) was performed immediately after apnea testing. We measured partial pressure of oxygen, arterial (PaO2) before and after RM. The primary outcomes were oxygenation (PaO2 to fraction of inspired oxygen [FiO2] ratio) and the severity of radiographic atelectasis (proportion of lung without aeration on computed tomography scans after brain death, quantified using an image analysis algorithm) in those who became organ donors. Outcomes in RM patients were compared with control patients undergoing apnea testing without RM in the previous 2 years.

RESULTS

Recruitment maneuver was performed in 54 patients after apnea testing, with a median immediate increase in PaO2 of 63 mm Hg (interquartile range 0-109, p = 0.07). Eighteen RM cases resulted in hypotension, but none were life-threatening. Of this cohort, 37 patients became organ donors, compared with 37 donors who had apnea testing without RM. The PaO2:FiO2 ratio was higher in the RM group (355 ± 129 vs. 288 ± 127, p = 0.03), and fewer had hypoxemia (PaO2:FiO2 ratio < 300 mm Hg, 22% vs. 57%; p = 0.04) at the start of donor management. The RM group showed less radiographic atelectasis (median 6% vs. 13%, p = 0.045). Although there was no difference in lungs transplanted (35% vs. 24%, p = 0.44), both better oxygenation and less atelectasis were associated with a higher likelihood of lungs being transplanted.

CONCLUSIONS

Recruitment maneuver after apnea testing reduces hypoxemia and atelectasis in organ donors after brain death. This effect may translate into more lungs being transplanted.

Conditioning-based therapeutics for aneurysmal subarachnoid hemorrhage - A critical review

Aneurysmal subarachnoid hemorrhage (SAH) carries significant mortality and morbidity, with nearly half of SAH survivors having major cognitive dysfunction that impairs their functional status, emotional health, and quality of life. Apart from the initial hemorrhage severity, secondary brain injury due to early brain injury and delayed cerebral ischemia plays a leading role in patient outcome after SAH. While many strategies to combat secondary brain injury have been developed in preclinical studies and tested in late phase clinical trials, only one (nimodipine) has proven efficacious for improving long-term functional outcome. The causes of these failures are likely multitude, but include use of therapies targeting only one element of what has proven to be multifactorial brain injury process. Conditioning is a therapeutic strategy that leverages endogenous protective mechanisms to exert powerful and remarkably pleiotropic protective effects against injury to all major cell types of the CNS. The aim of this article is to review the current body of evidence for the use of conditioning agents in SAH, summarize the underlying neuroprotective mechanisms, and identify gaps in the current literature to guide future investigation with the long-term goal of identifying a conditioning-based therapeutic that significantly improves functional and cognitive outcomes for SAH patients.

CSF-Based Volumetric Imaging Biomarkers Highlight Incidence and Risk Factors for Cerebral Edema After Ischemic Stroke

BACKGROUND

Cerebral edema has primarily been studied using midline shift or clinical deterioration as end points, which only captures the severe and delayed manifestations of a process affecting many patients with stroke. Quantitative imaging biomarkers that measure edema severity across the entire spectrum could improve its early detection, as well as identify relevant mediators of this important stroke complication.

METHODS

We applied an automated image analysis pipeline to measure the displacement of cerebrospinal fluid (ΔCSF) and the ratio of lesional versus contralateral hemispheric cerebrospinal fluid (CSF) volume (CSF ratio) in a cohort of 935 patients with hemispheric stroke with follow-up computed tomography scans taken a median of 26 h (interquartile range 24-31) after stroke onset. We determined diagnostic thresholds based on comparison to those without any visible edema. We modeled baseline clinical and radiographic variables against each edema biomarker and assessed how each biomarker was associated with stroke outcome (modified Rankin Scale at 90 days).

RESULTS

The displacement of CSF and CSF ratio were correlated with midline shift (r = 0.52 and - 0.74, p < 0.0001) but exhibited broader ranges. A ΔCSF of greater than 14% or a CSF ratio below 0.90 identified those with visible edema: more than half of the patients with stroke met these criteria, compared with only 14% who had midline shift at 24 h. Predictors of edema across all biomarkers included a higher National Institutes of Health Stroke Scale score, a lower Alberta Stroke Program Early CT score, and lower baseline CSF volume. A history of hypertension and diabetes (but not acute hyperglycemia) predicted greater ΔCSF but not midline shift. Both ΔCSF and a lower CSF ratio were associated with worse outcome, adjusting for age, National Institutes of Health Stroke Scale score, and Alberta Stroke Program Early CT score (odds ratio 1.7, 95% confidence interval 1.3-2.2 per 21% ΔCSF).

CONCLUSIONS

Cerebral edema can be measured in a majority of patients with stroke on follow-up computed tomography using volumetric biomarkers evaluating CSF shifts, including in many without visible midline shift. Edema formation is influenced by clinical and radiographic stroke severity but also by chronic vascular risk factors and contributes to worse stroke outcomes.

Intravenous Levothyroxine for Unstable Brain-Dead Heart Donors

BACKGROUND

Hemodynamic instability and myocardial dysfunction are major factors preventing the transplantation of hearts from organ donors after brain death. Intravenous levothyroxine is widely used in donor care, on the basis of observational data suggesting that more organs may be transplanted from donors who receive hormonal supplementation.

METHODS

In this trial involving 15 organ-procurement organizations in the United States, we randomly assigned hemodynamically unstable potential heart donors within 24 hours after declaration of death according to neurologic criteria to open-label infusion of intravenous levothyroxine (30 μg per hour for a minimum of 12 hours) or saline placebo. The primary outcome was transplantation of the donor heart; graft survival at 30 days after transplantation was a prespecified recipient safety outcome. Secondary outcomes included weaning from vasopressor therapy, donor ejection fraction, and number of organs transplanted per donor.

RESULTS

Of the 852 brain-dead donors who underwent randomization, 838 were included in the primary analysis: 419 in the levothyroxine group and 419 in the saline group. Hearts were transplanted from 230 donors (54.9%) in the levothyroxine group and 223 (53.2%) in the saline group (adjusted risk ratio, 1.01; 95% confidence interval [CI], 0.97 to 1.07; P = 0.57). Graft survival at 30 days occurred in 224 hearts (97.4%) transplanted from donors assigned to receive levothyroxine and 213 hearts (95.5%) transplanted from donors assigned to receive saline (difference, 1.9 percentage points; 95% CI, -2.3 to 6.0; P<0.001 for noninferiority at a margin of 6 percentage points). There were no substantial between-group differences in weaning from vasopressor therapy, ejection fraction on echocardiography, or organs transplanted per donor, but more cases of severe hypertension and tachycardia occurred in the levothyroxine group than in the saline group.

CONCLUSIONS

In hemodynamically unstable brain-dead potential heart donors, intravenous levothyroxine infusion did not result in significantly more hearts being transplanted than saline infusion. (Funded by Mid-America Transplant and others; ClinicalTrials.gov number, NCT04415658.).

Intraoperative Blood Pressure and Carbon Dioxide Values during Aneurysmal Repair and the Outcomes after Aneurysmal Subarachnoid Hemorrhage

Cerebral autoregulation impairment is a critical aspect of subarachnoid hemorrhage (SAH)-induced secondary brain injury and is also shown to be an independent predictor of delayed cerebral ischemia (DCI) and poor neurologic outcomes. Interestingly, intraoperative hemodynamic and ventilatory parameters were shown to influence patient outcomes after SAH. The aim of the current study was to evaluate the association of intraoperative hypotension and hypocapnia with the occurrence of angiographic vasospasm, DCI, and neurologic outcomes at discharge. Intraoperative data were collected for 390 patients with aneurysmal SAH who underwent general anesthesia for aneurysm clipping or coiling between January 2010 and May 2018. We measured the mean intraoperative blood pressure and end-tidal carbon dioxide (ETCO2), as well as the area under the curve (AUC) for the burden of hypotension: SBP below 100 or MBP below 65 and hypocapnia (ETCO2 < 30), during the intraoperative period. The outcome measures were angiographic vasospasm, DCI, and the neurologic outcomes at discharge as measured by the modified Rankin scale score (an mRS of 0-2 is a good outcome, and 3-6 is a poor outcome). Univariate and logistic regression analyses were performed to evaluate whether blood pressure (BP) and ETCO2 variables were independently associated with outcome measures. Out of 390 patients, 132 (34%) developed moderate-to-severe vasospasm, 114 (29%) developed DCI, and 46% (169) had good neurologic outcomes at discharge. None of the measured intraoperative BP and ETCO2 variables were associated with angiographic vasospasm, DCI, or poor neurologic outcomes. Our study did not identify an independent association between the degree of intraoperative hypotension or hypocapnia in relation to angiographic vasospasm, DCI, or the neurologic outcomes at discharge in SAH patients.

Imaging biomarkers of cerebral edema automatically extracted from routine CT scans of large vessel occlusion strokes

BACKGROUND AND PURPOSE

Volumetric and densitometric biomarkers have been proposed to better quantify cerebral edema after stroke, but their relative performance has not been rigorously evaluated.

METHODS

Patients with large vessel occlusion stroke from three institutions were analyzed. An automated pipeline extracted brain, cerebrospinal fluid (CSF), and infarct volumes from serial CTs. Several biomarkers were measured: change in global CSF volume from baseline (ΔCSF); ratio of CSF volumes between hemispheres (CSF ratio); and relative density of infarct region compared with mirrored contralateral region (net water uptake [NWU]). These were compared to radiographic standards, midline shift and relative hemispheric volume (RHV) and malignant edema, defined as deterioration resulting in need for osmotic therapy, decompressive surgery, or death.

RESULTS

We analyzed 255 patients with 210 baseline CTs, 255 24-hour CTs, and 81 72-hour CTs. Of these, 35 (14%) developed malignant edema and 63 (27%) midline shift. CSF metrics could be calculated for 310 (92%), while NWU could only be obtained from 193 (57%). Peak midline shift was correlated with baseline CSF ratio (ρ = -.22) and with CSF ratio and ΔCSF at 24 hours (ρ = -.55/.63) and 72 hours (ρ = -.66/.69), but not with NWU (ρ = .15/.25). Similarly, CSF ratio was correlated with RHV (ρ = -.69/-.78), while NWU was not. Adjusting for age, National Institutes of Health Stroke Scale, tissue plasminogen activator treatment, and Alberta Stroke Program Early CT Score, CSF ratio (odds ratio [OR]: 1.95 per 0.1, 95% confidence interval [CI]: 1.52-2.59) and ΔCSF at 24 hours (OR: 1.87 per 10%, 95% CI: 1.47-2.49) were associated with malignant edema.

CONCLUSION

CSF volumetric biomarkers can be automatically measured from almost all routine CTs and correlate better with standard edema endpoints than net water uptake.

Early Brain Injury After Subarachnoid Hemorrhage: Incidence and Mechanisms

Aneurysmal subarachnoid hemorrhage is a devastating condition causing significant morbidity and mortality. While outcomes from subarachnoid hemorrhage have improved in recent years, there continues to be significant interest in identifying therapeutic targets for this disease. In particular, there has been a shift in emphasis toward secondary brain injury that develops in the first 72 hours after subarachnoid hemorrhage. This time period of interest is referred to as the early brain injury period and comprises processes including microcirculatory dysfunction, blood-brain-barrier breakdown, neuroinflammation, cerebral edema, oxidative cascades, and neuronal death. Advances in our understanding of the mechanisms defining the early brain injury period have been accompanied by improved imaging and nonimaging biomarkers for identifying early brain injury, leading to the recognition of an elevated clinical incidence of early brain injury compared with prior estimates. With the frequency, impact, and mechanisms of early brain injury better defined, there is a need to review the literature in this area to guide preclinical and clinical study.

Abstract 9: Autoregulation-based Blood Pressure Targets After Endovascular Thrombectomy

Background: Optimal level blood pressure (BP) targets in acute stroke remain elusive. Tailored hemodynamic management after endovascular thrombectomy (EVT) may reduce the risk of reperfusion injury and promote penumbral recovery. Our study aimed to evaluate the relationship between personalized autoregulation-based BP targets, secondary brain injury, and functional outcomes.

Methods: We prospectively enrolled 200 patients with acute ischemic stroke who underwent EVT. Autoregulatory function was continuously measured for >=24 hours using simultaneous recordings of near-infrared spectroscopy and mean arterial pressure (MAP). The resulting autoregulatory index was used to calculate and trend the BP range at which autoregulation was most preserved. Percent time and “dose” that MAP exceeded the upper limit or dropped below the lower limit of autoregulation (ULA, LLA) were calculated for each patient. Hemodynamic parameters were correlated with short-term clinical endpoints (symptomatic ICH), biomarkers of secondary brain injury (net water uptake, hemorrhagic transformation (HT), infarct progression), and 90-day functional outcomes.

Results: Personalized BP targets were successfully computed in 195 patients (mean age 70 ± 16, 45% female, mean NIHSS 14, mean monitoring time 31 ± 28 hours). Time above the ULA was associated with worse functional outcomes at 90-days after adjusting for age, sex, NIHSS, ASPECTS and TICI (adjusted OR per 10% increase 1.4, 95% CI 1.1-1.6, P=0.004). The burden of hyperperfusion was significantly greater among patients with HT (median 2.7 vs. 3.2 mmHg*min, p=0.01) and sICH (median 2.8 vs. 4.8 mmHg*min, p=0.05) than in those without it. Furthermore, time spent above the ULA was significantly correlated with net water uptake at 72 hours (r=0.37, p=0.03). Among patients with unsuccessful reperfusion, there was a non-significant correlation between time below the LLA and infarct progression (r=0.35, p=0.064).

Conclusions: In the largest study conducted to date, deviations from personalized BP targets were associated with an increased risk of secondary brain injury and worse functional outcomes. Autoregulation-oriented BP management represents a promising strategy for maximizing recovery after ischemic stroke.

Abstract 12: Higher Blood Pressure Trajectories After Endovascular Thrombectomy Are Associated With Cerebral Edema Development

Introduction: High blood pressure after endovascular thrombectomy (EVT) can cause cerebral hyperemia and disrupt the blood-brain barrier. However, its role in cerebral edema development is incompletely understood. In this study, we examined the relationship between post-EVT systolic blood pressure (SBP) trajectories and cerebral edema.

Methods: We prospectively enrolled patients with large-vessel occlusion stroke who underwent EVT. Cerebrospinal fluid (CSF) volume was measured using a deep-learning algorithm on CT images at baseline, 24 hours, and 72 hours after stroke. The ratio of CSF volumes between hemispheres was calculated. Automated segmentation of infarct regions on follow-up scans was used to measure net water uptake (NWU), the ratio of density within infarcted tissue relative to the mirrored contralateral region. Latent variable mixture modeling (LVMM) divided patients into SBP trajectory groups during the first 72 hours post-EVT (Fig. 1A). Measures of edema (change in CSF ratio, NWU) were compared between groups.

Results: One hundred patients (mean age 70 ± 16, mean NIHSS 15) were analyzed. Edema was assessed by a gradual increase in NWU (20.5, 27.0) at 24 and 72 hours, respectively, and by a reduction in CSF ratio (0.95, 0.78, 0.68) in the affected hemisphere at baseline, 24 hours, and 72 hours, respectively. LVMM identified five SBP trajectories. Higher SBP trajectories were associated with higher NWU (Fig. 1B) but not lower CSF ratio at 24 hours (p<0.001 and p=0.343, respectively). After adjusting for age, admission NIHSS, and TICI score, the moderate-to-high and high-to-moderate trajectory groups were independently associated with higher NWU (aOR 11.40, 95% CI 2.14-20.66) and (aOR 10.97, 95% CI 0.12-21.82), relative to the low and moderate groups.

Conclusions: Higher SBP trajectories are associated with an increase in NWU post-EVT. NWU is a promising radiographic biomarker for measuring cerebral edema during the early phase after stroke.

Automated Quantification of Compartmental Blood Volumes Enables Prediction of Delayed Cerebral Ischemia and Outcomes After Aneurysmal Subarachnoid Hemorrhage

OBJECTIVE

The role of hemorrhage volume in risk of vasospasm, delayed cerebral ischemia (DCI), and poor outcomes after aneurysmal subarachnoid hemorrhage (SAH) is well established. However, the relative contribution of blood within individual compartments is unclear. We present an automated technique for measuring not only total but also volumes of blood in each major compartment after SAH.

METHODS

We trained convolutional neural networks to identify compartmental blood (cisterns, sulci, and ventricles) from baseline computed tomography scans of patients with SAH. We compared automated blood volumes against traditional markers of bleeding (modified Fisher score [mFS], Hijdra sum score [HSS]) in 190 SAH patients for prediction of vasospasm, DCI, and functional status (modified Rankin Scale) at hospital discharge.

RESULTS

Combined cisternal and sulcal volume was better correlated with mFS and HSS than cisternal volume alone (ρ = 0.63 vs. 0.58 and 0.75 vs. 0.70, P < 0.001). Only blood volume in combined cisternal plus sulcal compartments was independently associated with DCI (OR 1.023 per mL, 95% CI 1.002-1.048), after adjusting for clinical factors while ventricular blood volume was not. Total and specifically sulcal blood volume was strongly associated with poor outcome (OR 1.03 per mL, 1.01-1.06, P = 0.006 and OR 1.04, 1.00-1.08 for sulcal) as was HSS (OR 1.06 per point, 1.00-1.12, P = 0.04), while mFS was not (P = 0.24).

CONCLUSIONS

An automated imaging algorithm can measure the volume of bleeding after SAH within individual compartments, demonstrating cisternal plus sulcal (and not ventricular) blood contributes to risk of DCI/vasospasm. Automated blood volume was independently associated with outcome, while qualitative grading was not.

Collateral Flow: Prolonging the Ischemic Penumbra

This editorial serves as an introduction to the Special Issue on Collateral Flow: Prolonging the Ischemic Penumbra

A Polygenic Risk Score Based on a Cardioembolic Stroke Multitrait Analysis Improves a Clinical Prediction Model for This Stroke Subtype

Background

Occult atrial fibrillation (AF) is one of the major causes of embolic stroke of undetermined source (ESUS). Knowing the underlying etiology of an ESUS will reduce stroke recurrence and/or unnecessary use of anticoagulants. Understanding cardioembolic strokes (CES), whose main cause is AF, will provide tools to select patients who would benefit from anticoagulants among those with ESUS or AF. We aimed to discover novel loci associated with CES and create a polygenetic risk score (PRS) for a more efficient CES risk stratification.

Methods

Multitrait analysis of GWAS (MTAG) was performed with MEGASTROKE-CES cohort (n = 362,661) and AF cohort (n = 1,030,836). We considered significant variants and replicated those variants with MTAG p-value < 5 × 10⁻⁸ influencing both traits (GWAS-pairwise) with a p-value < 0.05 in the original GWAS and in an independent cohort (n = 9,105). The PRS was created with PRSice-2 and evaluated in the independent cohort.

Results

We found and replicated eleven loci associated with CES. Eight were novel loci. Seven of them had been previously associated with AF, namely, CAV1, ESR2, GORAB, IGF1R, NEURL1, WIPF1, and ZEB2. KIAA1755 locus had never been associated with CES/AF, leading its index variant to a missense change (R1045W). The PRS generated has been significantly associated with CES improving discrimination and patient reclassification of a model with age, sex, and hypertension.

Conclusion

The loci found significantly associated with CES in the MTAG, together with the creation of a PRS that improves the predictive clinical models of CES, might help guide future clinical trials of anticoagulant therapy in patients with ESUS or AF.

Automated Measurement of Net Water Uptake From Baseline and Follow-Up CTs in Patients With Large Vessel Occlusion Stroke

Quantifying the extent and evolution of cerebral edema developing after stroke is an important but challenging goal. Lesional net water uptake (NWU) is a promising CT-based biomarker of edema, but its measurement requires manually delineating infarcted tissue and mirrored regions in the contralateral hemisphere. We implement an imaging pipeline capable of automatically segmenting the infarct region and calculating NWU from both baseline and follow-up CTs of large-vessel occlusion (LVO) patients. Infarct core is extracted from CT perfusion images using a deconvolution algorithm while infarcts on follow-up CTs were segmented from non-contrast CT (NCCT) using a deep-learning algorithm. These infarct masks were flipped along the brain midline to generate mirrored regions in the contralateral hemisphere of NCCT; NWU was calculated as one minus the ratio of densities between regions, removing voxels segmented as CSF and with HU outside thresholds of 20-80 (normal hemisphere and baseline CT) and 0-40 (infarct region on follow-up). Automated results were compared with those obtained using manually-drawn infarcts and an ASPECTS region-of-interest based method that samples densities within the infarct and normal hemisphere, using intraclass correlation coefficient (ρ). This was tested on serial CTs from 55 patients with anterior circulation LVO (including 66 follow-up CTs). Baseline NWU using automated core was 4.3% (IQR 2.6-7.3) and correlated with manual measurement (ρ = 0.80, p < 0.0001) and ASPECTS (r = -0.60, p = 0.0001). Automatically segmented infarct volumes (median 110-ml) correlated to manually-drawn volumes (ρ = 0.96, p < 0.0001) with median Dice similarity coefficient of 0.83 (IQR 0.72-0.90). Automated NWU was 24.6% (IQR 20-27) and highly correlated to NWU from manually-drawn infarcts (ρ = 0.98) and the sampling-based method (ρ = 0.68, both p < 0.0001). We conclude that this automated imaging pipeline is able to accurately quantify region of infarction and NWU from serial CTs and could be leveraged to study the evolution and impact of edema in large cohorts of stroke patients.

Inhalational Versus Intravenous Anesthetic Conditioning for Subarachnoid Hemorrhage-Induced Delayed Cerebral Ischemia

BACKGROUND

Inhalational anesthetics were associated with reduced incidence of angiographic vasospasm and delayed cerebral ischemia (DCI) in patients with aneurysmal subarachnoid hemorrhage (SAH). Whether intravenous anesthetics provide similar level of protection is not known.

METHODS

Anesthetic data were collected retrospectively for patients with SAH who received general anesthesia for aneurysm repair between January 1, 2014 and May 31, 2018, at 2 academic centers in the United States (one employing primarily inhalational and the other primarily intravenous anesthesia with propofol). We compared the outcomes of angiographic vasospasm, DCI, and neurological outcome (measured by disposition at hospital discharge), between the 2 sites, adjusting for potential confounders.

RESULTS

We compared 179 patients with SAH receiving inhalational anesthetics at one institution to 206 patients with SAH receiving intravenous anesthetics at the second institution. The rates of angiographic vasospasm between inhalational versus intravenous anesthetic groups were 32% versus 52% (odds ratio, 0.49 [CI, 0.32-0.75]; P=0.001) and DCI were 21% versus 40% (odds ratio, 0.47 [CI, 0.29-0.74]; P=0.001), adjusting for imbalances between sites/groups, Hunt-Hess and Fisher grades, type of aneurysm treatment, and American Society of Anesthesiology status. No impact of anesthetics on neurological outcome at time of discharge was noted with rates of good discharge outcome between inhalational versus intravenous anesthetic groups at (78% versus 72%, P=0.23).

CONCLUSIONS

Our data suggest that those who received inhalational versus intravenous anesthetic for ruptured aneurysm repair had significant protection against SAH-induced angiographic vasospasm and DCI. Although we cannot fully disentangle site-specific versus anesthetic effects in this comparative study, these results, when coupled with preclinical data demonstrating a similar protective effect of inhalational anesthetics on vasospasm and DCI, suggest that inhalational anesthetics may be preferable for patients with SAH undergoing aneurysm repair. Additional investigations examining the effect of inhalational anesthetics on other SAH outcomes such as early brain injury and long-term neurological outcomes are warranted.

Multi-ancestry GWAS reveals excitotoxicity associated with outcome after ischaemic stroke

During the first hours after stroke onset, neurological deficits can be highly unstable: some patients rapidly improve, while others deteriorate. This early neurological instability has a major impact on long-term outcome. Here, we aimed to determine the genetic architecture of early neurological instability measured by the difference between the National Institutes of Health Stroke Scale (NIHSS) within 6 h of stroke onset and NIHSS at 24 h. A total of 5876 individuals from seven countries (Spain, Finland, Poland, USA, Costa Rica, Mexico and Korea) were studied using a multi-ancestry meta-analyses. We found that 8.7% of NIHSS at 24 h of variance was explained by common genetic variations, and also that early neurological instability has a different genetic architecture from that of stroke risk. Eight loci (1p21.1, 1q42.2, 2p25.1, 2q31.2, 2q33.3, 5q33.2, 7p21.2 and 13q31.1) were genome-wide significant and explained 1.8% of the variability suggesting that additional variants influence early change in neurological deficits. We used functional genomics and bioinformatic annotation to identify the genes driving the association from each locus. Expression quantitative trait loci mapping and summary data-based Mendelian randomization indicate that ADAM23 (log Bayes factor = 5.41) was driving the association for 2q33.3. Gene-based analyses suggested that GRIA1 (log Bayes factor = 5.19), which is predominantly expressed in the brain, is the gene driving the association for the 5q33.2 locus. These analyses also nominated GNPAT (log Bayes factor = 7.64) ABCB5 (log Bayes factor = 5.97) for the 1p21.1 and 7p21.1 loci. Human brain single-nuclei RNA-sequencing indicates that the gene expression of ADAM23 and GRIA1 is enriched in neurons. ADAM23, a presynaptic protein and GRIA1, a protein subunit of the AMPA receptor, are part of a synaptic protein complex that modulates neuronal excitability. These data provide the first genetic evidence in humans that excitotoxicity may contribute to early neurological instability after acute ischaemic stroke.

Hemispheric CSF volume ratio quantifies progression and severity of cerebral edema after acute hemispheric stroke

As swelling occurs, CSF is preferentially displaced from the ischemic hemisphere. The ratio of CSF volume in the stroke-affected hemisphere to that in the contralateral hemisphere may quantify the progression of cerebral edema. We automatically segmented CSF from 1,875 routine CTs performed within 96 hours of stroke onset in 924 participants of a stroke cohort study. In 737 subjects with follow-up imaging beyond 24-hours, edema severity was classified as affecting less than one-third of the hemisphere (CED-1), large hemispheric infarction (LHI, over one-third the hemisphere), without midline shift (CED-2) or with midline shift (CED-3). Malignant edema was LHI resulting in deterioration, requiring osmotic therapy, surgery, or resulting in death. Hemispheric CSF ratio was lower on baseline CT in those with LHI (0.91 vs. 0.97, p < 0.0001) and decreased more rapidly in those with LHI who developed midline shift (0.01 per hour for CED-3 vs. 0.004/hour CED-2). The ratio at 24-hours was lower in those with midline shift (0.41, IQR 0.30-0.57 vs. 0.66, 0.56-0.81 for CED-2). A ratio below 0.50 provided 90% sensitivity, 82% specificity for predicting malignant edema among those with LHI (AUC 0.91, 0.85-0.96). This suggests that the hemispheric CSF ratio may provide an accessible early biomarker of edema severity.

Accelerating Prediction of Malignant Cerebral Edema After Ischemic Stroke with Automated Image Analysis and Explainable Neural Networks

BACKGROUND

Malignant cerebral edema is a devastating complication of stroke, resulting in deterioration and death if hemicraniectomy is not performed prior to herniation. Current approaches for predicting this relatively rare complication often require advanced imaging and still suffer from suboptimal performance. We performed a pilot study to evaluate whether neural networks incorporating data extracted from routine computed tomography (CT) imaging could enhance prediction of edema in a large diverse stroke cohort.

METHODS

An automated imaging pipeline retrospectively extracted volumetric data, including cerebrospinal fluid (CSF) volumes and the hemispheric CSF volume ratio, from baseline and 24 h CT scans performed in participants of an international stroke cohort study. Fully connected and long short-term memory (LSTM) neural networks were trained using serial clinical and imaging data to predict those who would require hemicraniectomy or die with midline shift. The performance of these models was tested, in comparison with regression models and the Enhanced Detection of Edema in Malignant Anterior Circulation Stroke (EDEMA) score, using cross-validation to construct precision-recall curves.

RESULTS

Twenty of 598 patients developed malignant edema (12 required surgery, 8 died). The regression model provided 95% recall but only 32% precision (area under the precision-recall curve [AUPRC] 0.74), similar to the EDEMA score (precision 28%, AUPRC 0.66). The fully connected network did not perform better (precision 33%, AUPRC 0.71), but the LSTM model provided 100% recall and 87% precision (AUPRC 0.97) in the overall cohort and the subgroup with a National Institutes of Health Stroke Scale (NIHSS) score ≥ 8 (p = 0.0001 vs. regression and fully connected models). Features providing the most predictive importance were the hemispheric CSF ratio and NIHSS score measured at 24 h.

CONCLUSIONS

An LSTM neural network incorporating volumetric data extracted from routine CT scans identified all cases of malignant cerebral edema by 24 h after stroke, with significantly fewer false positives than a fully connected neural network, regression model, and the validated EDEMA score. This preliminary work requires prospective validation but provides proof of principle that a deep learning framework could assist in selecting patients for surgery prior to deterioration.

Assessment of asthma control in users of oral anti-asthma medications

BACKGROUND: Despite guidelines recommending inhalation therapy as the preferred choice, oral therapy is still widely used in the treatment of asthma in India. However, data about the level of asthma control and healthcare use in patients on oral anti-asthma medications are scarce.METHODS: A retrospective study was conducted to assess the level of asthma control and healthcare use in patients taking oral anti-asthma medications.RESULTS: The study population consisted of 381 adults randomly selected from health screening programmes. All subjects were already receiving oral anti-asthma medications; however, up to 72% had not been diagnosed with asthma by their treating doctors prior to the screening programmes. The cohort had a mean age of 48.26 ± 13.83 years (70% males) and mean peak expiratory flow of 245 ± 78.93 mL/sec. The mean Asthma Control Questionnaire 5 (ACQ-5) score was 2.53 ± 1.15, with respectively 33%, 49.3% and 32.6% reporting at least one episode of breathlessness, one emergency doctor visit and one hospitalisation due to asthma or its symptoms in the past year.CONCLUSION: Underdiagnosis and inappropriate management, as indicated by the poor asthma control and increased hospitalisations seen in this study, is probably a key contributor to the increased burden of the disease in India.

RP11-362K2.2:RP11-767I20.1 Genetic Variation Is Associated with Post-Reperfusion Therapy Parenchymal Hematoma. A GWAS Meta-Analysis

Stroke is one of the most common causes of death and disability. Reperfusion therapies are the only treatment available during the acute phase of stroke. Due to recent clinical trials, these therapies may increase their frequency of use by extending the time-window administration, which may lead to an increase in complications such as hemorrhagic transformation, with parenchymal hematoma (PH) being the more severe subtype, associated with higher mortality and disability rates. Our aim was to find genetic risk factors associated with PH, as that could provide molecular targets/pathways for their prevention/treatment and study its genetic correlations to find traits sharing genetic background. We performed a GWAS and meta-analysis, following standard quality controls and association analysis (fastGWAS), adjusting age, NIHSS, and principal components. FUMA was used to annotate, prioritize, visualize, and interpret the meta-analysis results. The total number of patients in the meta-analysis was 2034 (216 cases and 1818 controls). We found rs79770152 having a genome-wide significant association (beta 0.09, p-value 3.90 × 10⁻⁸) located in the RP11-362K2.2:RP11-767I20.1 gene and a suggestive variant (rs13297983: beta 0.07, p-value 6.10 × 10⁻⁸) located in PCSK5 associated with PH occurrence. The genetic correlation showed a shared genetic background of PH with Alzheimer’s disease and white matter hyperintensities. In addition, genes containing the ten most significant associations have been related to aggregated amyloid-β, tau protein, white matter microstructure, inflammation, and matrix metalloproteinases.

The Stroke Neuro-Imaging Phenotype Repository: An Open Data Science Platform for Stroke Research

Stroke is one of the leading causes of death and disability worldwide. Reducing this disease burden through drug discovery and evaluation of stroke patient outcomes requires broader characterization of stroke pathophysiology, yet the underlying biologic and genetic factors contributing to outcomes are largely unknown. Remedying this critical knowledge gap requires deeper phenotyping, including large-scale integration of demographic, clinical, genomic, and imaging features. Such big data approaches will be facilitated by developing and running processing pipelines to extract stroke-related phenotypes at large scale. Millions of stroke patients undergo routine brain imaging each year, capturing a rich set of data on stroke-related injury and outcomes. The Stroke Neuroimaging Phenotype Repository (SNIPR) was developed as a multi-center centralized imaging repository of clinical computed tomography (CT) and magnetic resonance imaging (MRI) scans from stroke patients worldwide, based on the open source XNAT imaging informatics platform. The aims of this repository are to: (i) store, manage, process, and facilitate sharing of high-value stroke imaging data sets, (ii) implement containerized automated computational methods to extract image characteristics and disease-specific features from contributed images, (iii) facilitate integration of imaging, genomic, and clinical data to perform large-scale analysis of complications after stroke; and (iv) develop SNIPR as a collaborative platform aimed at both data scientists and clinical investigators. Currently, SNIPR hosts research projects encompassing ischemic and hemorrhagic stroke, with data from 2,246 subjects, and 6,149 imaging sessions from Washington University's clinical image archive as well as contributions from collaborators in different countries, including Finland, Poland, and Spain. Moreover, we have extended the XNAT data model to include relevant clinical features, including subject demographics, stroke severity (NIH Stroke Scale), stroke subtype (using TOAST classification), and outcome [modified Rankin Scale (mRS)]. Image processing pipelines are deployed on SNIPR using containerized modules, which facilitate replicability at a large scale. The first such pipeline identifies axial brain CT scans from DICOM header data and image data using a meta deep learning scan classifier, registers serial scans to an atlas, segments tissue compartments, and calculates CSF volume. The resulting volume can be used to quantify the progression of cerebral edema after ischemic stroke. SNIPR thus enables the development and validation of pipelines to automatically extract imaging phenotypes and couple them with clinical data with the overarching aim of enabling a broad understanding of stroke progression and outcomes.

COPD exacerbation rates are higher in non-smoker patients in India

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is common among non-smokers exposed to solid fuel combustion at home. Different clinical characteristics in these patients may have significant therapeutic and prognostic implications.METHODS: We used medical record review and a questionnaire among COPD patients at 15 centres across India to capture data on demographic details, different types of exposures and clinical characteristics. Chest radiography and pulmonary function testing were performed in all 1984 cases; C-reactive protein and exhaled breath nitric oxide were measured wherever available.RESULTS: There were 1388 current or ex-smokers and 596 (30.0%) non-smokers who included 259 (43.5%) male and 337 (56.5%) female patients. Sputum production was significantly more common in smokers with COPD (P < 0.05). The frequency of acute symptomatic worsening, emergency visits and hospitalisation were significantly higher (P < 0.05) in non-smokers with COPD; however, intensive care unit admissions were similar in the two groups. There was no significant difference with respect to the use of bronchodilators, inhalational steroids or home nebulisation among smoker and non-smoker patients. The mean predicted forced expiratory volume in 1 sec in smokers (43.1%) was significantly lower than in non-smokers (46.5%).CONCLUSION: Non-smoker COPD, more commonly observed in women exposed to biomass fuels, was characterised by higher rate of exacerbations and higher healthcare resource utilisation.

Conditioning Effect of Inhalational Anesthetics on Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH) has been identified as an independent predictor of poor outcome in numerous studies.

OBJECTIVE

To investigate the potential protective role of inhalational anesthetics against angiographic vasospasm, DCI, and neurologic outcome in SAH patients.

METHODS

After Institutional Review Board approval, data were collected retrospectively for SAH patients who received general anesthesia for aneurysm repair between January 1st, 2010 and May 31st, 2018. Primary outcomes were angiographic vasospasm, DCI, and neurologic outcome as measured by modified Rankin scale at hospital discharge. Univariate and logistic regression analysis were performed to identify independent predictors of these outcomes.

RESULTS

The cohort included 390 SAH patients with an average age of 56 ± 15 (mean ± SD). Multivariate logistic regression analysis identified inhalational anesthetic only technique, Hunt-Hess grade, age, anterior circulation aneurysm and average intraoperative mean blood pressure as independent predictors of angiographic vasospasm. Inhalational anesthetic only technique and modified Fishers grade were identified as independent predictors of DCI. No impact on neurological outcome at time of discharge was noted.

CONCLUSION

Our data provide additional evidence that inhalational anesthetic conditioning in SAH patients affords protection against angiographic vasospasm and new evidence that it exerts a protective effect against DCI. When coupled with similar results from preclinical studies, our data suggest further investigation into the impact of inhalational anesthetic conditioning on SAH patients, including elucidating the most effective dosing regimen, defining the therapeutic window, determining whether a similar protective effect against early brain injury, and on long-term neurological outcome exists.

Abstract P423: Race and Ethnicity Influence Perihematomal Edema Volume in Supratentorial Intracerebral Hemorrhage

Introduction: Perihematomal Edema (PHE) is a neuroimaging biomarker of secondary brain injury in patients with spontaneous, non-traumatic intracerebral hemorrhage (ICH). There are limited data on racial/ethnic differences in the development of PHE. This dearth of data is partially driven by the time-consuming process of manually segmenting PHE. Leveraging a validated automated pipeline for PHE segmentation, we evaluated whether race and ethnicity influence baseline PHE volume in patients with ICH.

Methods: The Ethnic/Racial Variations in Intracerebral Hemorrhage (ERICH) study is a prospective, multicenter study of ICH that recruited 1,000 adult participants from each of three racial/ethnic groups (non-Hispanic White, non-Hispanic Black, and Hispanic). We applied a previously validated deep learning algorithm to automatically determine PHE volumes on baseline CTs in these study participants. Quality control procedures were used to include only sufficiently accurate PHE measurements. Linear regression was used to identify factors associated with log-transformed PHE volume and to identify differences across Ethnic/Racial groups.

Results: Our imaging pipeline provided good quality baseline PHE measurements on 2,008 out of 3,000 ERICH study participants. After excluding infratentorial hemorrhages (273) and those with missing or null baseline ICH volume (49), 1,686 remained for analysis (median age 59 [IQR 51-71], 687 [41%] female sex). Median PHE volume was 12.0 (IQR 4.8-27.1) for whites, 11.9 (IQR 4.5-26.1) for Hispanics and 8.3 (IQR 3.0-19.2) for blacks. Compared to Blacks, Hispanics (beta 0.22; 95%CI 0.11-0.32; p<0.001) and Whites (beta 0.20; 95%CI 0.07-0.33; p=0.003) had higher baseline PHE volumes, in multivariable analysis adjusting for age, sex, ICH location, log-baseline ICH volume, log-baseline intraventricular volume, and systolic blood pressure on admission.

Conclusion: Race and ethnicity influence the volume of baseline PHE. Further studies are needed to validate our results and investigate the biological underpinnings of this difference.

Automated Quantification of Reduced Sulcal Volume Identifies Early Brain Injury After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND PURPOSE

Early brain injury may be a more significant contributor to poor outcome after aneurysmal subarachnoid hemorrhage (aSAH) than vasospasm and delayed cerebral ischemia. However, studying this process has been hampered by lack of a means of quantifying the spectrum of injury. Global cerebral edema (GCE) is the most widely accepted manifestation of early brain injury but is currently assessed only through subjective, qualitative or semi-quantitative means. Selective sulcal volume (SSV), the CSF volume above the lateral ventricles, has been proposed as a quantitative biomarker of GCE, but is time-consuming to measure manually. Here we implement an automated algorithm to extract SSV and evaluate the age-dependent relationship of reduced SSV on early outcomes after aSAH.

METHODS

We selected all adults with aSAH admitted to a single institution with imaging within 72 hours of ictus. Scans were assessed for qualitative presence of GCE. SSV was automatically segmented from serial CTs using a deep learning-based approach. Early SSV was the lowest SSV from all early scans. Modified Rankin Scale score of 4 to 6 at hospital discharge was classified as a poor outcome.

RESULTS

Two hundred forty-four patients with aSAH were included. Sixty-five (27%) had GCE on admission while 24 developed it subsequently within 72 hours. Median SSV on admission was 10.7 mL but frequently decreased, with minimum early SSV being 3.0 mL (interquartile range, 0.3-11.9). Early SSV below 5 mL was highly predictive of qualitative GCE (area under receiver-operating-characteristic curve, 0.90). Reduced early SSV was an independent predictor of poor outcome, with a stronger effect in younger patients.

CONCLUSIONS

Automated assessment of SSV provides an objective biomarker of GCE that can be leveraged to quantify early brain injury and dissect its impact on outcomes after aSAH. Such quantitative analysis suggests that GCE may be more impactful to younger patients with SAH.

Early Neurological Change After Ischemic Stroke Is Associated With 90-Day Outcome

BACKGROUND AND PURPOSE

Large-scale observational studies of acute ischemic stroke (AIS) promise to reveal mechanisms underlying cerebral ischemia. However, meaningful quantitative phenotypes attainable in large patient populations are needed. We characterize a dynamic metric of AIS instability, defined by change in National Institutes of Health Stroke Scale score (NIHSS) from baseline to 24 hours baseline to 24 hours (NIHSSbaseline - NIHSS24hours = ΔNIHSS6-24h), to examine its relevance to AIS mechanisms and long-term outcomes.

METHODS

Patients with NIHSS prospectively recorded within 6 hours after onset and then 24 hours later were enrolled in the GENISIS study (Genetics of Early Neurological Instability After Ischemic Stroke). Stepwise linear regression determined variables that independently influenced ΔNIHSS6-24h. In a subcohort of tPA (alteplase)-treated patients with large vessel occlusion, the influence of early sustained recanalization and hemorrhagic transformation on ΔNIHSS6-24h was examined. Finally, the association of ΔNIHSS6-24h with 90-day favorable outcomes (modified Rankin Scale score 0-2) was assessed. Independent analysis was performed using data from the 2 NINDS-tPA stroke trials (National Institute of Neurological Disorders and Stroke rt-PA).

RESULTS

For 2555 patients with AIS, median baseline NIHSS was 9 (interquartile range, 4-16), and median ΔNIHSS6-24h was 2 (interquartile range, 0-5). In a multivariable model, baseline NIHSS, tPA-treatment, age, glucose, site, and systolic blood pressure independently predicted ΔNIHSS6-24h (R2=0.15). In the large vessel occlusion subcohort, early sustained recanalization and hemorrhagic transformation increased the explained variance (R2=0.27), but much of the variance remained unexplained. ΔNIHSS6-24h had a significant and independent association with 90-day favorable outcome. For the subjects in the 2 NINDS-tPA trials, ΔNIHSS3-24h was similarly associated with 90-day outcomes.

CONCLUSIONS

The dynamic phenotype, ΔNIHSS6-24h, captures both explained and unexplained mechanisms involved in AIS and is significantly and independently associated with long-term outcomes. Thus, ΔNIHSS6-24h promises to be an easily obtainable and meaningful quantitative phenotype for large-scale genomic studies of AIS.

Point-of-care blood gas analyzers have an impact on the acceptance of donor lungs for transplantation

An organ donor PaO2 above 40 kPa is generally required for lung transplantation. Point-of-care (POC) blood gas analyzers are commonly used by organ procurement organizations (OPO) but may underestimate the PaO2 at high levels. We hypothesized that changing to a more accurate blood gas analyzer would result in additional lungs transplanted. All PaO2 measurements on organ donors managed at one OPO's recovery center were performed on an i-STAT POC analyzer prior to October 2015, and on a GEM 4000 subsequently. For 24 weeks, all blood gases were tested simultaneously on both analyzers. We compared lung outcomes of 147 donors in the year prior to this change (using the i-STAT) with 56 donors in the 24-week study period (using the GEM 4000 for lung allocation). When the PaO2 was above 40 kPa, the i-STAT PaO2 was 7.2 kPa lower on average than the GEM 4000. When the GEM PaO2 measured between 40 and 50 kPa, the corresponding i-STAT PaO2 value registered less than 40 kPa 25 out of 48 times (52%), with an average difference of 7.3 kPa (SD = 2.9). The rate of lungs transplanted using the GEM 4000 was 48% compared with 35% in the year prior using the i-STAT (p = .11), with equivalent recipient outcomes. The i-STAT analyzer underestimated the PaO2 above 40 kPa and changing to a more accurate PaO2 analyzer may increase lungs transplanted.

Abstract 3127: To investigate the role of BRAF V600E co-occurring mutations in Langerhans cell histiocytosis (LCH)

a. Introduction :

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasia caused by alterations of several genes in the MAPKinase pathway. The cell of origin is a white blood cell known as a dendritic cell priviously called as histiocyte characterized by a unique cytoplasmic organelle, the Birbeck granule, and the expression of CD1a and class II major histocompatibility complex molecules . The mutations cause these dendritic cells to attract other white blood cells and cause a “lesion” in any organ of the body. LCH has multi-orgnan involvement affecting skin bones, lymph nodes, brain etc. Systemic symptoms may include fever, bone pain, weight loss, jaundice, diabetes insipidus.

b. Description:

LCH is a rare sporadic, non-hereditary and non-malignant disease with unknown etiology characterized with a clonal proliferation of pathologic cells.Recent discovery of recurrent somatic mutations, BRAFV600E in MAPK pathway genes at critical stages of myeloid hematopoietic differentiation in LCH patients supports redefinition of the disease as a myeloproliferative disorder and provides opportunities to develop novel approaches to diagnosis and therapy. In the present proposal, we intend to analyze the BRAFV600E status along with other co-occurring mutations in a cohort of pediatric LCH patients by DNA sequencing in bone marrow samples or Peripheral Blood. Additionally we approach the above unanswered questions by applying an improved machine learning approach for classification and defining an algorithm for disease into different clusters for immediate clinical implication and to address its clinical heterogeneity.

c. Results :

We screened about 5 LCH patients and performed tageted exome seq to asertain the mutational profile of these patients. Sequencing detected BRAF V600E mutation in 3 of 5 samples for a mutation frequency of 60%. IHC based immunofloroscence shows that the intensity of phospho-MEK and phospho-ERK staining shows no significant alterations samples with mutation in BRAF. We are currently investigating mutations in other members of MAK pathways

d. Conclusion :

BRAF-V600E mutations were detected in few of our LCH patients. Neverless seeing the disease heterogeneity, we expect additionall mutations. More studies are needed to investigate mutations in the MAPK pathways that could efffect the course of disease management.We further plan to integrate the clinical and genomic findings to design a predictive model for the disease outcome.

Citation Format: Subhradip Karmakar, R Dhar, K Purkayastha, R Seth, S Karmakar. To investigate the role of BRAF V600E co-occurring mutations in Langerhans cell histiocytosis (LCH) [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3127.

Admitting Low-Risk Patients With Intracerebral Hemorrhage to a Neurological Step-Down Unit Is Safe, Results in Shorter Length of Stay, and Reduces Intensive Care Utilization: A Retrospective Controlled Cohort Study

Background and Purpose

Patients suffering intracerebral hemorrhage (ICH) are at risk for early neurologic deterioration and are often admitted to intensive care units (ICU) for observation. There is limited data on the safety of admitting low-risk patients with ICH to a non-ICU setting. We hypothesized that admitting such patients to a neurologic step-down unit (SDU) is safe and less resource-intensive.

Methods

We performed a retrospective analysis of patients with primary ICH admitted to our SDU. We compared this cohort to a control group of ICH patients admitted to a neurologic-ICU (NICU) at a partner institution. We analyzed patients with supratentorial ICH ≤15 cc, Glasgow Coma Scale ≥ 13, National Institutes of Health Stroke Scale ≤ 10, and no to minimal intraventricular hemorrhage. Primary end points were (re-)admission to an NICU and rates of hematoma expansion (HE). We also compared total NICU days and hospital length of stay (LOS).

Results

Eighty patients with ICH were admitted to the SDU. Only 2 required transfer to the NICU for complications related to ICH, including 1 for HE. Seventy-four SDU patients met inclusion criteria and were compared to 58 patients admitted to an NICU. There was no difference in rates of NICU (re-)admission (7 vs 2, P = .17) or rates of HE (3 vs 5, P = .28). Median NICU days were 0 versus 1 (P < .001). Step-down unit admission was associated with shorter LOS (3 vs 4 days, P = .05).

Conclusions

Select patients with ICH can be safely admitted to an SDU. This may reduce LOS and ICU utilization. We also propose criteria for admitting patients with ICH to an SDU.

Automated quantitative assessment of cerebral edema after ischemic stroke using CSF volumetrics

Reduction in CSF volume from baseline to follow-up CT at or beyond 24 -hs can serve as a quantitative biomarker of cerebral edema after stroke. We have demonstrated that assessment of CSF displacement reflects edema metrics such as lesion volume, midline shift, and neurologic deterioration. We have also developed a neural network-based image segmentation algorithm that can automatically measure CSF volume on serial CT scans from stroke patients. We have integrated this algorithm into an image processing pipeline that can extract this edema biomarker from large cohorts of stroke patients. Finally, we have created a stroke repository that can archive and process images from thousands of stroke patients in order to measure CSF volumetrics. We plan on applying this metric as a quantitative endophenotype of cerebral edema to facilitate early prediction of clinical deterioration as well as large-scale genetic studies.

Abstract WP88: Volumetric Measures of Hemorrhagic Transformation After Acute Ischemic Stroke Predicts Neurological Deterioration Better Than Radiologic Classification

Introduction: Hemorrhagic transformation (HT) after acute ischemic stroke (AIS) may contribute to neurologic deterioration. The current radiologic classification of HT is qualitative and distinguishes petechial hemorrhagic infarction from parenchymal hematoma (PH-1 and PH-2). However, this grading scheme is subjective and may not accurately reflect the impact of HT on neurological status and outcome. We sought to evaluate whether the volume of hemorrhage was a better marker of deterioration.

Methods: We evaluated AIS patients with follow-up CT imaging from a prospective stroke genetics study. HT seen within 36 hours of AI was classified using ECASS criteria. In addition, we outlined all confluent areas of hemorrhage to derive hemorrhage volume (HV). We calculated ΔNIHSS as the difference between baseline and 24-hour NIHSS. Early neurological deterioration (END) was defined as ΔNIHSS of -4 points or more. Association of radiologic HT grade and HV with ΔNIHSS and END were analyzed using linear regression and receiver-operating-curve testing.

Results: We analyzed 948 stroke patients with median NIHSS 7 (IQR 4-14), 64% receiving tPA and ΔNIHSS +2 (IQR 0-5). 294 (31%) had HT (146 HI1, 63 HI2, 42 PH1 and 43 PH2). HT was associated with higher baseline NIHSS but not with tPA treatment or ΔNIHSS. END occurred in 113 (12%) including 46 with HT (16%) vs. 67 (10%) without HT (p=0.02). Amongst those with HT, the radiologic grade was not associated with ΔNIHSS or END (20% of PH2, 20% of PH1 vs. 15% of HI1/HI2, p=0.40). However, greater HV was associated with ΔNIHSS (adjusting for baseline NIHSS and tPA, estimate -1.5 point per 10-ml, p=0.0001) and with END (those with END had median HV 7 vs. 3-ml, p=0.001). A cut-off of 12-ml had 45% sensitivity and 90% specificity for END (AUC of 0.72).

Conclusion: We demonstrated that while HT was associated with a higher risk of END, the ECASS classification alone did not distinguish those who worsened. It appears that hemorrhage volume may better predict worsening NIHSS and END with moderate sensitivity.

Abstract 63: Infarct Volume and Rate of Edema Growth Predicts Need for Intervention in Patients With Cerebellar Infarction

Background: Predictors of malignant edema in patients with acute cerebellar infarction are understudied. We hypothesized that greater infarct volume and CT-defined edema growth would predict individuals requiring acute intervention.

Methods: Admissions to a tertiary care neurological ICU with acute cerebellar infarction over three year period were identified. Primary endpoint was defined as needing medical and/or surgical “intervention”: osmotic therapy, extra-ventricular drainage, or surgical decompression. Visible regions of infarct-related hypodensity in the cerebellum were manually outlined on serial CTs to ascertain infarct volumes. Infarct ratio was defined as the ratio of infarct volume to posterior fossa volume on initial CT showing ischemia. Rate in infarct-related edema growth was measured as the change in infarct ratio over time between sequential head CTs.

Results: Of the 60 patients identified, 27 (45%) received interventions. All except one received osmotic therapy, while 15 patients underwent surgical intervention. Compared with the no-intervention cohort, intervention cohort was more likely to have diabetes (21% vs 48%, p = 0.03) and larger initial infarct ratio (0.12 vs 0.22, p = 0.001). Diabetes (OR, 6.3 95% CI, 1.6-25.3) and infarct ratio (OR, 3.2; 95% Cl, 1.6-6.3) were independent predictors of intervention. The rate of edema growth was faster in the intervention cohort (time*cohort p =0.005) (Fig A). A subgroup analysis of 34 patients with at least 3 CTs showed the intervention cohort had greater edema growth rate (-0.0001/hr vs 0.0044/hr, p = 0.02). Multivariate analysis showed edema growth independently predicted intervention (Fig B) and improved the AUC from 0.78 to 0.90 (Fig C), while diabetes was not retained (p=0.056).

Conclusion: Baseline infarct ratio and rate of edema growth within the first 4 days may provide clinically useful markers to select patients with cerebellar infarction who will benefit from intervention.

Outcomes and risk factors of cholecystectomy in high risk patients: A case series

Introduction

Many studies looked at outcomes and risk factors in laparoscopic cholecystectomies in general, including a few studies on risk factors and scoring systems in predicting conversion to open surgery. Little data has been produced on high-risk patients undergoing cholecystectomy. Identifying risk factors in this group could help stratify decision making regarding best management strategies.

The aim of this study was to investigate outcomes of laparoscopic cholecystectomies in patients with ASA 3 and 4.

Methods

Data was collected and collated from a prospectively maintained database of all laparoscopic cholecystectomies performed by 13 general surgeons in a single unit. Case notes were reviewed for all patients with ASA 3 and 4 between 2013 and 2017. Data analysis was performed using R studio v 3.4.

Results

244 cases were reviewed. Common bile duct was dilated in 52 cases (21.31%). Gall bladder wall was thick in 102 (41.8%) of the patients. Surgery was elective in 203 (83.2%) of the patients. ERCP was performed in 41 (16.9%) of the patients prior to surgery. 150 patients (62.2%) stayed for 1 day while 36 (14.9%) stayed for 2 days and the remaining 55 (22.9%) stayed for 3 days or more. Complications occurred in 37 (15.16%) of the patients while 23 (9.43%) of the patients were readmitted. 7 patients (2.87%) returned to theatre and 8 (3.28%) stayed in ITU post-op. Two patients died (0.82%).

Conclusion

Laparoscopic cholecystectomies in higher risk populations are safe. Alternative methods such as cholecystostomy and ERCP may be of benefit in these patients.

•

Gallstone disease represents a significant volume of elective and emergency work in the United Kingdom.

•

The primary aim of the study was to explore the factors that lead to complications in high risk patients (ASA 3-4).

•

Histological gallbladder thickness and emergency surgery were the factors most strongly associated with negative outcomes.

•

Age greater than 65 as an independent variable does not lead to an increase in negative outcomes.

•

Cholecystectomy is a relatively safe procedure in what is typically considered higher risk patients.

Elucidation of the de Vries behavior in terms of the orientational order parameter, apparent tilt angle, and field-induced tilt angle for smectic liquid crystals by polarized infrared spectroscopy

We report experimental results of the orientational order parameter, the apparent tilt angle, and the field-induced tilt angle for three chiral smectic liquid crystalline materials investigated using infrared (IR) polarized spectroscopy. The common feature in these materials is use of the core 5-methyl-2- pyrimidine benzoate as the central part of the mesogen. This core is terminated by siloxane or carbosilane chains on one of the ends and by the chiral alkoxy chains on the opposite. These compounds exhibit low concomitant layer shrinkage at the smectic A^{*} (SmA^{*}) to smectic C^{*} (SmC^{*}) transition temperature and within the SmC^{*} phase itself. The maximum layer shrinkage in SmC^{*} is observed as ∼1.5%. We calculate the apparent orientational order parameter, S_{app} in the laboratory reference frame from the observed IR absorbance for homeotropic aligned samples, and the true order parameter, S, is calculated using the measured tilt angle and is also interpolated from Iso-SmA^{*} transition temperature closer to SmC^{*} phase. The apparent tilt angle in the SmA^{*} phase calculated from a comparison of order parameters S and S_{app} is found to be significantly large. A low magnitude of S_{app} found for homeotropic aligned samples in the SmA^{*} phase indicates that the order parameter plays a vital role in determining the de Vries characteristics, especially of exhibiting larger apparent tilt angles. Furthermore there is a significant increase in the true order parameter at temperatures close to SmA^{*} to SmC^{*} transition temperature in all three compounds. The planar-aligned samples are used to study the dependence of induced tilt angle on the applied electric field. The generalized Langevin-Debye model given by Shen et al. reasonably fits the experimental data on the field-induced tilt angle. The results show that the dipole moment of the tilt correlated domain in SmA^{*} diverges as temperature is lowered to the SmA^{*}-SmC^{*} transition temperature. The generalized Langevin-Debye model is also found to be extremely effective in confirming some of the conclusions of the de Vries behavior.

Reduction in Cerebrospinal Fluid Volume as an Early Quantitative Biomarker of Cerebral Edema After Ischemic Stroke

Background and Purpose- Cerebral edema (CED) develops in the hours to days after stroke; the resulting increase in brain volume may lead to midline shift (MLS) and neurological deterioration. The time course and implications of edema formation are not well characterized across the spectrum of stroke. We analyzed displacement of cerebrospinal fluid (ΔCSF) as a dynamic quantitative imaging biomarker of edema formation. Methods- We selected subjects enrolled in a stroke cohort study who presented within 6 hours of onset and had baseline and ≥1 follow-up brain computed tomography scans available. We applied a neural network-based algorithm to quantify hemispheric CSF volume at each imaging time point and modeled CSF trajectory over time (using a piecewise linear mixed-effects model). We evaluated ΔCSF within the first 24 hours as an early biomarker of CED (defined as developing MLS on computed tomography beyond 24 hours) and poor outcome (modified Rankin Scale score, 3-6). Results- We had serial imaging in 738 subjects with stroke, of whom 91 (13%) developed CED with MLS. Age did not differ (69 versus 70 years), but baseline National Institutes of Health Stroke Scale was higher (16 versus 7) and baseline CSF volume lower (132 versus 161 mL, both P<0.001) in those with CED. ΔCSF was faster in those developing MLS, with the majority seen by 24 hours (36% versus 11% or 2.4 versus 0.8 mL/h; P<0.0001). Risk of CED almost doubled for every 10% ΔCSF within 24 hours (odds ratio, 1.76 [95% CI, 1.46-2.14]), adjusting for age, glucose, and National Institutes of Health Stroke Scale. Risk of neurological deterioration (1.6-point increase in National Institutes of Health Stroke Scale at 24 hours) and poor outcome (adjusted odds ratio, 1.34 [95% CI, 1.15-1.56]) was also greater for every 10% increase in ΔCSF. Conclusions- CSF volumetrics provides quantitative evaluation of early edema formation. ΔCSF from baseline to 24-hour computed tomography is a promising early biomarker for the development of MLS and worse neurological outcome.

Deep Learning for Automated Measurement of Hemorrhage and Perihematomal Edema in Supratentorial Intracerebral Hemorrhage

Background and Purpose- Volumes of hemorrhage and perihematomal edema (PHE) are well-established biomarkers of primary and secondary injury, respectively, in spontaneous intracerebral hemorrhage. An automated imaging pipeline capable of accurately and rapidly quantifying these biomarkers would facilitate large cohort studies evaluating underlying mechanisms of injury. Methods- Regions of hemorrhage and PHE were manually delineated on computed tomography scans of patients enrolled in 2 intracerebral hemorrhage studies. Manual ground-truth masks from the first cohort were used to train a fully convolutional neural network to segment images into hemorrhage and PHE. The primary outcome was automated-versus-human concordance in hemorrhage and PHE volumes. The secondary outcome was voxel-by-voxel overlap of segmentations, quantified by the Dice similarity coefficient (DSC). Algorithm performance was validated on 84 scans from the second study. Results- Two hundred twenty-four scans from 124 patients with supratentorial intracerebral hemorrhage were used for algorithm derivation. Median volumes were 18 mL (interquartile range, 8-43) for hemorrhage and 12 mL (interquartile range, 5-30) for PHE. Concordance was excellent (0.96) for automated quantification of hemorrhage and good (0.81) for PHE, with DSC of 0.90 (interquartile range, 0.85-0.93) and 0.54 (0.39-0.65), respectively. External validation confirmed algorithm accuracy for hemorrhage (concordance 0.98, DSC 0.90) and PHE (concordance 0.90, DSC 0.55). This was comparable with the consistency observed between 2 human raters (DSC 0.90 for hemorrhage, 0.57 for PHE). Conclusions- We have developed a deep learning-based imaging algorithm capable of accurately measuring hemorrhage and PHE volumes. Rapid and consistent automated biomarker quantification may accelerate powerful and precise studies of disease biology in large cohorts of intracerebral hemorrhage patients.

A Randomized Trial of Intravenous Thyroxine for Brain-Dead Organ Donors With Impaired Cardiac Function

RATIONALE

Brain death (BD) precipitates cardiac dysfunction impairing the ability to transplant hearts from eligible organ donors. Retrospective studies have suggested that thyroid hormone may enhance myocardial recovery and increase hearts transplanted. We performed a randomized trial evaluating whether intravenous thyroxine (T4) improves cardiac function in BD donors with impaired ejection fraction (EF).

METHODS

All heart-eligible donors managed at a single-organ procurement organization (OPO) underwent protocolized fluid resuscitation. Those weaned off vasopressors underwent transthoracic echocardiography (TTE) within 12 hours of BD and, if EF was below 60%, were randomized to T4 infusion or no T4 for 8 hours, after which TTE was repeated.

RESULTS

Of 77 heart-eligible donors, 36 were weaned off vasopressors. Ejection fraction was depressed in 30, of whom 28 were randomized to T4 (n = 17) vs control (n = 11). Baseline EF was comparable (45%, interquartile range [IQR] 42.5-47.5 vs 40%, 40-50, P = .32). Ejection fraction did not improve more with T4 (10%, IQR 5-15 vs 5%, 0-12.5, P = .24), although there was a trend to more hearts transplanted (59% vs 27%, P = .14). This difference appeared to be accounted for by more donors with a history of drug use in the T4 group, who exhibited greater improvements in EF (15% vs 0% without drug use, P = .01) and more often had hearts transplanted (12 of 19 vs 1 of 9, P = .01).

CONCLUSIONS

In this small randomized study of BD donors with impaired cardiac function, T4 infusion did not result in greater cardiac recovery. A larger randomized trial comparing T4 to placebo appears warranted but would require collaboration across multiple OPOs.

A Randomized Trial of Brief Versus Extended Seizure Prophylaxis After Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Seizures occur in 10-20% of patients with subarachnoid hemorrhage (SAH), predominantly in the acute phase. However, anticonvulsant prophylaxis remains controversial, with studies suggesting a brief course may be adequate and longer exposure may be associated with worse outcomes. Nonetheless, in the absence of controlled trials to inform practice, patients continue to receive variable chemoprophylaxis. The objective of this study was to compare brief versus extended seizure prophylaxis after aneurysmal SAH.

METHODS

We performed a prospective, single-center, randomized, open-label trial of a brief (3-day) course of levetiracetam (LEV) versus extended treatment (until hospital discharge). The primary outcome was in-hospital seizure. Secondary outcomes included drug discontinuation and functional outcome.

RESULTS

Eighty-four SAH patients had been randomized when the trial was terminated due to slow enrollment. In-hospital seizures occurred in three (9%) of 35 in the brief LEV group versus one (2%) of 49 in the extended group (p = 0.2). Ten (20%) of the extended group discontinued LEV prematurely, primarily due to sedation. Four of five seizures (including one pre-randomization) occurred in patients with early brain injury (EBI) on computed tomography (CT) scans (adjusted OR 12.5, 95% CI 1.2-122, p = 0.03). Good functional outcome (mRS 0-2) was more likely in the brief LEV group (83 vs. 61%, p = 0.04).

CONCLUSIONS

This study was underpowered to demonstrate superiority of extended LEV for seizure prophylaxis, although a trend to benefit was seen. Seizures primarily occurred in those with radiographic EBI, suggesting targeted prophylaxis may be preferable. Larger trials are required to evaluate optimal chemoprophylaxis in SAH, especially in light of worse outcomes in those receiving extended treatment.

Evidence for a conditioning effect of inhalational anesthetics on angiographic vasospasm after aneurysmal subarachnoid hemorrhage

OBJECTIVE

Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (SAH) is characterized by large-artery vasospasm, distal autoregulatory dysfunction, cortical spreading depression, and microvessel thrombi. Large-artery vasospasm has been identified as an independent predictor of poor outcome in numerous studies. Recently, several animal studies have identified a strong protective role for inhalational anesthetics against secondary brain injury after SAH including DCI-a phenomenon referred to as anesthetic conditioning. The aim of the present study was to assess the potential role of inhalational anesthetics against cerebral vasospasm and DCI in patients suffering from an SAH.

METHODS

After IRB approval, data were collected retrospectively for all SAH patients admitted to the authors' hospital between January 1, 2010, and December 31, 2013, who received general anesthesia with either inhalational anesthetics only (sevoflurane or desflurane) or combined inhalational (sevoflurane or desflurane) and intravenous (propofol) anesthetics during aneurysm treatment. The primary outcomes were development of angiographic vasospasm and development of DCI during hospitalization. Univariate and logistic regression analyses were performed to identify independent predictors of these endpoints.

RESULTS

The cohort included 157 SAH patients whose mean age was 56 ± 14 (± SD). An inhalational anesthetic-only technique was employed in 119 patients (76%), while a combination of inhalational and intravenous anesthetics was employed in 34 patients (22%). As expected, patients in the inhalational anesthetic-only group were exposed to significantly more inhalational agent than patients in the combination anesthetic group (p < 0.05). Multivariate logistic regression analysis identified inhalational anesthetic-only technique (OR 0.35, 95% CI 0.14-0.89), Hunt and Hess grade (OR 1.51, 95% CI 1.03-2.22), and diabetes (OR 0.19, 95% CI 0.06-0.55) as significant predictors of angiographic vasospasm. In contradistinction, the inhalational anesthetic-only technique had no significant impact on the incidence of DCI or functional outcome at discharge, though greater exposure to desflurane (as measured by end-tidal concentration) was associated with a lower incidence of DCI.

CONCLUSIONS

These data represent the first evidence in humans that inhalational anesthetics may exert a conditioning protective effect against angiographic vasospasm in SAH patients. Future studies will be needed to determine whether optimized inhalational anesthetic paradigms produce definitive protection against angiographic vasospasm; whether they protect against other events leading to secondary brain injury after SAH, including microvascular thrombi, autoregulatory dysfunction, blood-brain barrier breakdown, neuroinflammation, and neuronal cell death; and, if so, whether this protection ultimately improves patient outcome.

Burden of cerebral hypoperfusion in patients with delayed cerebral ischemia after subarachnoid hemorrhage

OBJECTIVE

Delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) may result in focal neurological deficits and cerebral infarction, believed to result from critical regional rather than global impairments in cerebral blood flow (CBF). However, the burden of such regional hypoperfusion has not been evaluated by gold-standard voxel-by-voxel CBF measurements. Specifically, the authors sought to determine whether the proportion of brain affected by hypoperfusion was greater in patients with DCI than in SAH controls without DCI and whether the symptomatic hemisphere (in those with lateralizing deficits) exhibited a greater cerebral hypoperfusion burden.

METHODS

Sixty-one patients with aneurysmal SAH underwent 15O PET to measure regional CBF during the period of risk for DCI (median 8 days after SAH, IQR 7-10 days). Regions of visibly abnormal brain on head CT studies, including areas of hemorrhage and infarction, were excluded. Burden of hypoperfusion was defined as the proportion of PET voxels in normal-appearing brain with CBF < 25 ml/100 g/min. Global CBF and hypoperfusion burden were compared between patients with and those without DCI at the time of PET. For patients with focal impairments from DCI, the authors also compared average CBF and hypoperfusion burden in symptomatic versus asymptomatic hemispheres.

RESULTS

Twenty-three patients (38%) had clinical DCI at the time of PET. Those with DCI had higher mean arterial pressure (MAP; 126 ± 14 vs 106 ± 12 mm Hg, p < 0.001) and 18 (78%) were on vasopressor therapy at the time of PET study. While global CBF was not significantly lower in patients with DCI (mean 39.4 ± 11.2 vs 43.0 ± 8.3 ml/100 g/min, p = 0.16), the burden of hypoperfusion was greater (20%, IQR 12%-23%, vs 12%, 9%-16%, p = 0.006). Burden of hypoperfusion performed better than global CBF as a predictor of DCI (area under the curve 0.71 vs 0.65, p = 0.044). Neither global CBF nor hypoperfusion burden differed in patients who responded to therapy compared to those who had not improved by the time of PET. Although hemispheric CBF was not lower in the symptomatic versus contralateral hemisphere in the 13 patients with focal deficits, there was a trend toward greater burden of hypoperfusion in the symptomatic hemisphere (21% vs 18%, p = 0.049).

CONCLUSIONS

The burden of hypoperfusion was greater in patients with DCI, despite hemodynamic therapies, higher MAP, and equivalent global CBF. Similarly, hypoperfusion burden was greater in the symptomatic hemisphere of DCI patients with focal deficits even though the average CBF was similar to that in the contralateral hemisphere. Evaluating the proportion of the brain with critical hypoperfusion after SAH may better capture the extent of DCI than averaging CBF across heterogenous brain regions.

A randomized trial comparing triiodothyronine (T3) with thyroxine (T4) for hemodynamically unstable brain-dead organ donors

RATIONALE

Brain-dead (BD) organ donors frequently exhibit hemodynamic instability and/or reversible cardiac dysfunction. Retrospective studies have suggested that thyroid hormone may stabilize hemodynamics and enhance myocardial recovery. Intravenous levothyroxine (T4) is most frequently utilized but studies have suggested that triiodothyronine (T3) may be superior. We performed a randomized comparative-effectiveness trial to address this uncertainty in donor management.

METHODS

All heart-eligible donors managed at a single OPO underwent standardized fluid resuscitation. If not weaned off vasopressors, donors underwent echocardiography (within 12 hours of BD) and were randomized to T3 or T4 infusion for eight hours.

RESULTS

A total of 37 BD donors were randomized (16 T3 vs 21 T4). Baseline ejection fraction (EF) was comparable (median 38% vs 45%, P = 0.87) as was vasopressor dosage (6 vs 12 μg/min of norepinephrine, NE, P = 0.12). Reduction in NE dose and proportion weaned off vasopressors was similar and LVEF improved in both groups (repeat EF: 50% vs 52.5%, P = 0.38) with almost half attaining EF ≥55%. Although more hearts were transplanted in the T3 group (10/16 vs 6/21, P = 0.04), this difference did not persist after adjusting for baseline imbalances in age and PF ratio.

CONCLUSIONS

Infusion of T3 does not appear to confer significant hemodynamic or cardiac benefits over T4 for hemodynamic unstable BD organ donors.