Brain Injury Is More Common in Venoarterial Extracorporeal Membrane Oxygenation Than Venovenous Extracorporeal Membrane Oxygenation: A Systematic Review and Meta-Analysis

Association of early changes in arterial carbon dioxide with acute brain injury in adult patients with extracorporeal membrane oxygenation: A ten-year retrospective study in a German tertiary care hospital

PURPOSE

To assess the association between fluctuations of arterial carbon dioxide early after start of extracorporeal membrane oxygenation (ECMO) with intracranial hemorrhage (ICH) or ischemic stroke (IS).

MATERIALS AND METHODS

This single-center retrospective study included patients who required ECMO for circulatory or respiratory failure between January 2011 and April 2021 and for whom a cerebral computed tomography (cCT) scan was available. Multivariable logistic regression models were fitted to evaluate the association between the relative change of arterial carbon dioxide (RelΔPaCO2) and ICH, IS or a composite of ICH, IS, and mortality.

RESULTS

In 618 patients (venovenous ECMO: n = 295; venoarterial ECMO: n = 323) ICH occurred more frequently in patients with respiratory failure (19.0%) compared with patients with circulatory failure (6.8%). Conversely, the incidence of IS was higher in patients with circulatory failure (19.2%) compared with patients with respiratory failure (4.7%). While patients with ECMO for respiratory failure were more likely to have ICH (OR 3.683 [95% CI: 1.855;7.309], p < 0.001), they had a lower odds for IS (OR 0.360 [95%CI: 0.158;0.820], p = 0.015) compared with patients with circulatory failure. There was no significant association between RelΔPaCO2 and ICH or IS.

CONCLUSIONS

Irrespective of the indication for ECMO, we did not find a significant association between the relative change in PaCO2 early after ECMO initiation and acute brain injury. Aside from early PaCO2 decline at cannulation, future studies should address fluctuations of PaCO2 throughout the course of ECMO support and their effect on acute brain injury.

Serum neurofilament light chain as a sensitive biomarker for neuromonitoring during extracorporeal membrane oxygenation

The use of extracorporeal membrane oxygenation (ECMO) has grown rapidly, driven by the COVID-19 pandemic. Despite its widespread adoption, neurological complications pose a significant risk, impacting both mortality and survivors' quality of life. Detecting these complications is challenging due to sedation and the heterogeneous nature of ECMO-associated neurological injury. Still, consensus of neurologic monitoring during ECMO is lacking since utilization and effectiveness of current neuromonitoring methods are limited. Especially in view of the heterogeneous nature of neurological injury during ECMO support an easily acquirable biomarker tracing neuronal damage independently from the underlying pathomechanism would be favorable. In a single-center prospective study on 34 severe acute respiratory distress syndrome (ARDS) patients undergoing ECMO, we explored the potential of serum neurofilament light chain levels (NfL) as a biomarker for neurological complications and its predictive power towards the overall outcome of ECMO patients. Individuals experiencing neurological complications (41%) demonstrated a notable rise in NfL levels (Tbaseline median 92.95 pg/ml; T24h median 132 pg/ml (IQR 88.6-924 pg/ml), p = 0.008; T7d median 248 pg/ml (IQR 157-1090 pg/ml), p = 0.001). Moreover, under ECMO therapy, these patients exhibited markedly elevated concentrations compared to those without neurological complications (T24h median 70.75 pg/ml (IQR 22.2-290 pg/ml), p = 0.023; T7d median 128 pg/ml (IQR 51.8-244 pg/ml), p = 0.002). There was no significant difference in the NfL dynamics between surviving patients and those who died during or shortly after ECMO therapy. While NfL indicates neuro-axonal damage during intensive care with ECMO therapy, we could not identify any correlation between survival outcome and the levels of NfL, indicating that NfL may not serve as a prognostic marker for survival. Nevertheless, additional studies involving a larger patient cohort are required.

Neurological monitoring and management for adult extracorporeal membrane oxygenation patients: Extracorporeal Life Support Organization consensus guidelines

BACKGROUND

Critical care of patients on extracorporeal membrane oxygenation (ECMO) with acute brain injury (ABI) is notable for a lack of high-quality clinical evidence. Here, we offer guidelines for neurological care (neurological monitoring and management) of adults during and after ECMO support.

METHODS

These guidelines are based on clinical practice consensus recommendations and scientific statements. We convened an international multidisciplinary consensus panel including 30 clinician-scientists with expertise in ECMO from all chapters of the Extracorporeal Life Support Organization (ELSO). We used a modified Delphi process with three rounds of voting and asked panelists to assess the recommendation levels.

RESULTS

We identified five key clinical areas needing guidance: (1) neurological monitoring, (2) post-cannulation early physiological targets and ABI, (3) neurological therapy including medical and surgical intervention, (4) neurological prognostication, and (5) neurological follow-up and outcomes. The consensus produced 30 statements and recommendations regarding key clinical areas. We identified several knowledge gaps to shape future research efforts.

CONCLUSIONS

The impact of ABI on morbidity and mortality in ECMO patients is significant. Particularly, early detection and timely intervention are crucial for improving outcomes. These consensus recommendations and scientific statements serve to guide the neurological monitoring and prevention of ABI, and management strategy of ECMO-associated ABI.

Neurologic complications in patients receiving aortic versus subclavian versus femoral arterial cannulation for post-cardiotomy extracorporeal life support: results of the PELS observational multicenter study

BACKGROUND

Cerebral perfusion may change depending on arterial cannulation site and may affect the incidence of neurologic adverse events in post-cardiotomy extracorporeal life support (ECLS). The current study compares patients' neurologic outcomes with three commonly used arterial cannulation strategies (aortic vs. subclavian/axillary vs. femoral artery) to evaluate if each ECLS configuration is associated with different rates of neurologic complications.

METHODS

This retrospective, multicenter (34 centers), observational study included adults requiring post-cardiotomy ECLS between January 2000 and December 2020 present in the Post-Cardiotomy Extracorporeal Life Support (PELS) Study database. Patients with Aortic, Subclavian/Axillary and Femoral cannulation were compared on the incidence of a composite neurological end-point (ischemic stroke, cerebral hemorrhage, brain edema). Secondary outcomes were overall in-hospital mortality, neurologic complications as cause of in-hospital death, and post-operative minor neurologic complications (seizures). Association between cannulation and neurological outcomes were investigated through linear mixed-effects models.

RESULTS

This study included 1897 patients comprising 26.5% Aortic (n = 503), 20.9% Subclavian/Axillary (n = 397) and 52.6% Femoral (n = 997) cannulations. The Subclavian/Axillary group featured a more frequent history of hypertension, smoking, diabetes, previous myocardial infarction, dialysis, peripheral artery disease and previous stroke. Neuro-monitoring was used infrequently in all groups. Major neurologic complications were more frequent in Subclavian/Axillary (Aortic: n = 79, 15.8%; Subclavian/Axillary: n = 78, 19.6%; Femoral: n = 118, 11.9%; p < 0.001) also after mixed-effects model adjustment (OR 1.53 [95% CI 1.02-2.31], p = 0.041). Seizures were more common in Subclavian/Axillary (n = 13, 3.4%) than Aortic (n = 9, 1.8%) and Femoral cannulation (n = 12, 1.3%, p = 0.036). In-hospital mortality was higher after Aortic cannulation (Aortic: n = 344, 68.4%, Subclavian/Axillary: n = 223, 56.2%, Femoral: n = 587, 58.9%, p < 0.001), as shown by Kaplan-Meier curves. Anyhow, neurologic cause of death (Aortic: n = 12, 3.9%, Subclavian/Axillary: n = 14, 6.6%, Femoral: n = 28, 5.0%, p = 0.433) was similar.

CONCLUSIONS

In this analysis of the PELS Study, Subclavian/Axillary cannulation was associated with higher rates of major neurologic complications and seizures. In-hospital mortality was higher after Aortic cannulation, despite no significant differences in incidence of neurological cause of death in these patients. These results encourage vigilance for neurologic complications and neuromonitoring use in patients on ECLS, especially with Subclavian/Axillary cannulation.

Neurophysiologic Features Reflecting Brain Injury During Pediatric ECMO Support

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) provides lifesaving support to critically ill patients who experience refractory cardiopulmonary failure but carries a high risk for acute brain injury. We aimed to identify characteristics reflecting acute brain injury in children requiring ECMO support.

METHODS

This is a prospective observational study from 2019 to 2022 of pediatric ECMO patients undergoing neuromonitoring, including continuous electroencephalography, cerebral oximetry, and transcranial Doppler ultrasound (TCD). The primary outcome was acute brain injury. Clinical and neuromonitoring characteristics were collected. Multivariate logistic regression was implemented to model odds ratios (ORs) and identify the combined characteristics that best discriminate risk of acute brain injury using the area under the receiver operating characteristic curve.

RESULTS

Seventy-five pediatric patients requiring ECMO support were enrolled in this study, and 62 underwent neuroimaging or autopsy evaluations. Of these 62 patients, 19 experienced acute brain injury (30.6%), including seven (36.8%) with arterial ischemic stroke, four (21.1%) with hemorrhagic stroke, seven with hypoxic-ischemic brain injury (36.8%), and one (5.3%) with both arterial ischemic stroke and hypoxic-ischemic brain injury. A univariate analysis demonstrated acute brain injury to be associated with maximum hourly seizure burden (p = 0.021), electroencephalographic suppression percentage (p = 0.022), increased interhemispheric differences in electroencephalographic total power (p = 0.023) and amplitude (p = 0.017), and increased differences in TCD Thrombolysis in Brain Ischemia (TIBI) scores between bilateral middle cerebral arteries (p = 0.023). Best subset model selection identified increased seizure burden (OR = 2.07, partial R2 = 0.48, p = 0.013), increased quantitative electroencephalographic interhemispheric amplitude differences (OR = 2.41, partial R2 = 0.48, p = 0.013), and increased interhemispheric TCD TIBI score differences (OR = 4.66, partial R2 = 0.49, p = 0.006) to be independently associated with acute brain injury (area under the receiver operating characteristic curve = 0.92).

CONCLUSIONS

Increased seizure burden and increased interhemispheric differences in both quantitative electroencephalographic amplitude and TCD MCA TIBI scores are independently associated with acute brain injury in children undergoing ECMO support.

Long-Term Neuropsychiatric, Neurocognitive, and Functional Outcomes of Patients Receiving ECMO: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Despite the common occurrence of neurologic complications during extracorporeal membrane oxygenation (ECMO) support, data on long-term neuropsychiatric, neurocognitive, and functional outcomes are sparse. We aimed to determine the prevalence of long-term neuropsychiatric symptoms, neurocognitive and functional impairment, and favorable neurologic outcomes in adult patients who receive ECMO.

METHODS

PubMed, Embase, Cochrane, Web of Science, and Scopus were searched for text related to ECMO and neuropsychiatric, neurocognitive, and functional outcomes from inception to May 3, 2023. Our primary outcome was the prevalence of neuropsychiatric symptoms (pain/discomfort, anxiety, depression, posttraumatic stress disorder [PTSD], and sleep disturbance) at long-term (≥6 months) follow-up. Our secondary outcomes were the prevalence of neurocognitive impairment (memory, attention, and reasoning), functional impairment (daily activities, physical activity/mobility, and personal/self-care), and favorable neurologic outcomes (Cerebral Performance Category ≤2, modified Rankin scale ≤3, or Glasgow Outcome Scale ≥4). This study was registered in PROSPERO (CRD42023420565).

RESULTS

We included 59 studies with 3,280 patients (median age 54 years, 69% male). The cohort consisted of 86% venoarterial (VA)-ECMO (n = 2,819) and 14% venovenous (VV)-ECMO (n = 461) patients. More than 10 tools were used to assess neuropsychiatric and neurocognitive outcomes, indicating a lack of standardization in assessment methodologies. The overall prevalence of neuropsychiatric symptoms was 41% (95% CI 33%-49%): pain/discomfort (52%, 95% CI 42%-63%), sleep disturbance (37%, 95% CI 0%-98%), anxiety (36%, 95% CI 27%-46%), depression (31%, 95% CI 22%-40%), and PTSD (18%, 95% CI 9%-29%). The prevalence of neurocognitive impairment was 38% (95% CI 13%-65%). The prevalence of functional impairment was 52% (95% CI 40%-64%): daily activities (54%, 95% CI 41%-66%), mobility (41%, 95% CI 28%-54%), and self-care (21%, 95% CI 13%-31%). The prevalence of neuropsychiatric symptoms in VV-ECMO patients was higher than that in VA-ECMO patients (55% [95% CI 34%-75%] vs 32% [95% CI 23%-41%], p = 0.01), though the prevalence of neurocognitive and functional impairment was not different between the groups. The prevalence of favorable neurologic outcomes was not different at various follow-ups: 3 months (23%, 95% CI 12%-36%), 6 months (25%, 95% CI 16%-35%), and ≥1 year (28%, 95% CI 21%-36%, p = 0.68).

DISCUSSION

A substantial proportion of ECMO patients seemed to experience neuropsychiatric symptoms and neurocognitive and functional impairments at long-term follow-up. Considerable heterogeneity in methodology for gauging these outcomes exists, warranting the need for standardization. Multicenter prospective observational studies are indicated to further investigate risk factors for these outcomes in ECMO-supported patients.

Intracranial hemorrhage in a large cohort of patients supported with veno-venous ECMO. A retrospective single-center analysis

BACKGROUND

Intracranial bleeding (ICB) is a serious complication during veno-venous extracorporeal membrane oxygenation (V-V ECMO), with potentially fatal consequences.

PURPOSE

This study aimed to evaluate the incidence, time of detection of ICB among patients treated with V-V ECMO and potential risk factors for developing ICB during V-V ECMO.

METHODS

Five hundred fifty six patients were included in this retrospective single center analysis.

RESULTS

Median time on V-V ECMO was 9 (IQR 6-15) days. Intracranial bleeding during V-V ECMO was detected in 10.9% of all patients (61 patients with ICB). Only 17 patients with ICB presented obvious clinical symptoms. Intracranial bleeding was detected on cerebral imaging in median after 5 days (IQR 1-14) after starting V-V ECMO. Overall survival to hospital discharge was 63.7% (ICB: 29.5%). Risk factors of ICB before starting V-V ECMO in univariable analysis were platelets <100/nl (OR: 3.82), creatinine >1.5mg/dl (OR: 1.98), norepinephrine >2.5mg/h (OR: 2.5), ASAT >80U/L (OR: 1.86), blood-urea >100mg/dl (OR: 1.81) and LDH >550u/L (OR: 2.07). Factors associated with cannulation were rapid decrease in paCO2 >35mmHg (OR: 2.56) and rapid decrease in norepinephrine >1mg/h (OR: 2.53). Multivariable analysis revealed low platelets, high paCO2 before ECMO, and rapid drop in paCO2 after V-V ECMO initiation as significant risk factors for ICB.

CONCLUSION

The results emphasize that ICB is a frequent complication during V-V ECMO. Many bleedings were incidental findings, therefore screening for ICB is advisable. The univariate risk factors reflect the underlying disease severity, coagulation disorders and peri-cannulation factors, and may help to identify patients at risk.

Correlations Between Quantitative EEG Parameters and Cortical Blood Flow in Patients Undergoing Extracorporeal Membrane Oxygenation With and Without Encephalopathy

PURPOSE

The neurologic examination of patients undergoing extracorporeal membrane oxygenation (ECMO) is crucial for evaluating irreversible encephalopathy but is often obscured by sedation or neuromuscular blockade. Noninvasive neuromonitoring modalities including diffuse correlation spectroscopy and EEG measure cerebral perfusion and neuronal function, respectively. We hypothesized that encephalopathic ECMO patients with greater degree of irreversible cerebral injury demonstrate less correlation between electrographic activity and cerebral perfusion than those whose encephalopathy is attributable to medications.

METHODS

We performed a prospective observational study of adults undergoing ECMO who underwent simultaneous continuous EEG and diffuse correlation spectroscopy monitoring. (Alpha + beta)/delta ratio and alpha/delta Rartio derived from quantitative EEG analysis were correlated with frontal cortical blood flow index. Patients who awakened and followed commands during sedation pauses were included in group 1, whereas patients who could not follow commands for most neuromonitoring were placed in group 2. (Alpha + beta)/delta ratio-blood flow index and ADR-BFI correlations were compared between the groups.

RESULTS

Ten patients (five in each group) underwent 39 concomitant continuous EEG and diffuse correlation spectroscopy monitoring sessions. Four patients (80%) in each group received some form of analgosedation during neuromonitoring. (Alpha + beta)/delta ratio-blood flow index correlation was significantly lower in group 2 than group 1 (left: 0.05 vs. 0.52, P = 0.03; right: -0.12 vs. 0.39, P = 0.04). Group 2 ADR-BFI correlation was lower only over the right hemisphere (-0.06 vs. 0.47, P = 0.04).

CONCLUSIONS

Correlation between (alpha + beta)/delta ratio and blood flow index were decreased in encephalopathic ECMO patients compared with awake ones, regardless of the analgosedation use. The combined use of EEG and diffuse correlation spectroscopy may have utility in monitoring cerebral function in ECMO patients.

Cerebral Autoregulation, Cerebral Hemodynamics, and Injury Biomarkers, in Patients with COVID-19 Treated with Veno-Venous Extracorporeal Membrane Oxygenation

BACKGROUND

This study aimed to describe the cerebrovascular dynamics, in particular cerebral autoregulation (CA), and cerebral biomarkers as neuron-specific enolase (NSE) in patients with a diagnosis of coronavirus disease 2019 and acute respiratory distress syndrome as well as undergoing veno-venous extracorporeal membrane treatment.

METHODS

This was a single center, observational study conducted in the intensive care unit of the University Hospital in Wroclaw from October 2020 to February 2022. Transcranial Doppler recordings of the middle cerebral artery conducted for at least 20 min were performed. Cerebral autoregulation (CA) was estimated by using the mean velocity index (Mxa), calculated as the moving correlation coefficient between slow-wave oscillations in cerebral blood flow velocity and arterial blood pressure. Altered CA was defined as a positive Mxa. Blood samples for the measurement of NSE were obtained at the same time as transcranial Doppler measurements.

RESULTS

A total of 16 patients fulfilled the inclusion criteria and were enrolled in the study. The median age was 39 (34-56) years. Altered CA was found in 12 patients, and six out of seven patients who died had altered CA. A positive Mxa was a significant predictor of mortality, with a sensitivity of 85.7%. We found that three out of five patients with pathological changes in brain computed tomography and six out of ten patients with neurological complications had altered CA. NSE was a significant predictor of mortality (cutoff value: 28.9 µg/L); area under the curve = 0.83, p = 0.006), with a strong relationship between increased level of NSE and altered CA, χ2 = 6.24; p = 0.035; φ = 0.69.

CONCLUSIONS

Patients with coronavirus disease 2019-related acute respiratory distress syndrome, requiring veno-venous extracorporeal membrane treatment, are likely to have elevated NSE levels and altered CA. The CA was associated with NSE values in this group. This preliminary analysis suggests that advanced neuromonitoring and evaluation of biomarkers should be considered in this population.

Subtypes and Mechanistic Advances of Extracorporeal Membrane Oxygenation-Related Acute Brain Injury

Extracorporeal membrane oxygenation (ECMO) is a frequently used mechanical cardiopulmonary support for rescuing critically ill patients for whom conventional medical therapies have failed. However, ECMO is associated with several complications, such as acute kidney injury, hemorrhage, thromboembolism, and acute brain injury (ABI). Among these, ABI, particularly intracranial hemorrhage (ICH) and infarction, is recognized as the primary cause of mortality during ECMO support. Furthermore, survivors often suffer significant long-term morbidities, including neurocognitive impairments, motor disturbances, and behavioral problems. This review provides a comprehensive overview of the different subtypes of ECMO-related ABI and the updated advance mechanisms, which could be helpful for the early diagnosis and potential neuromonitoring of ECMO-related ABI.

Pediatric ECLS Neurologic Management and Outcomes

Neurologic complications associated with extracorporeal life support (ECLS), including seizures, ischemia/infarction, and intracranial hemorrhage significantly increase morbidity and mortality in pediatric and neonatal patients. Prompt recognition of adverse neurologic events may provide a window to intervene with neuroprotective measures. Many neuromonitoring modalities are available with varying benefits and limitations. Several pre-ECLS and ECLS-related factors have been associated with an increased risk for neurologic complications. These may be patient- or circuit-related and include modifiable and non-modifiable factors. ECLS survivors are at risk for long-term neurological sequelae affecting neurodevelopmental outcomes. Possible long-term outcomes range from normal development to severe impairment. Patients should undergo a neurological evaluation prior to discharge, and neurodevelopmental assessments should be included in each patient's structured, multidisciplinary follow-up. Safe pediatric and neonatal ECLS management requires a thorough understanding of neurological complications, neuromonitoring techniques and limitations, considerations to minimize risk, and an awareness of possible long-term ramifications. With a focus on ECLS for respiratory failure, this manuscript provides a review of these topics and summarizes best practice guidelines from international organizations and expert consensus.

Prevalence, reasons, and timing of decisions to withhold/withdraw life-sustaining therapy for out-of-hospital cardiac arrest patients with extracorporeal cardiopulmonary resuscitation

BACKGROUND

Extracorporeal cardiopulmonary resuscitation (ECPR) is rapidly becoming a common treatment strategy for patients with refractory cardiac arrest. Despite its benefits, ECPR raises a variety of ethical concerns when the treatment is discontinued. There is little information about the decision to withhold/withdraw life-sustaining therapy (WLST) for out-of-hospital cardiac arrest (OHCA) patients after ECPR.

METHODS

We conducted a secondary analysis of data from the SAVE-J II study, a retrospective, multicenter study of ECPR in Japan. Adult patients who underwent ECPR for OHCA with medical causes were included. The prevalence, reasons, and timing of WLST decisions were recorded. Outcomes of patients with or without WLST decisions were compared. Further, factors associated with WLST decisions were examined.

RESULTS

We included 1660 patients in the analysis; 510 (30.7%) had WLST decisions. The number of WLST decisions was the highest on the first day and WSLT decisions were made a median of two days after ICU admission. Reasons for WLST were perceived unfavorable neurological prognosis (300/510 [58.8%]), perceived unfavorable cardiac/pulmonary prognosis (105/510 [20.5%]), inability to maintain extracorporeal cardiopulmonary support (71/510 [13.9%]), complications (10/510 [1.9%]), exacerbation of comorbidity before cardiac arrest (7/510 [1.3%]), and others. Patients with WLST had lower 30-day survival (WLST vs. no-WLST: 36/506 [7.1%] vs. 386/1140 [33.8%], p < 0.001). Primary cerebral disorders as cause of cardiac arrest and higher severity of illness at intensive care unit admission were associated with WLST decisions.

CONCLUSION

For approximately one-third of ECPR/OHCA patients, WLST was decided during admission, mainly because of perceived unfavorable neurological prognoses. Decisions and neurological assessments for ECPR/OHCA patients need further analysis.

Hypoxic-Ischemic Brain Injury in ECMO: Pathophysiology, Neuromonitoring, and Therapeutic Opportunities

Extracorporeal membrane oxygenation (ECMO), in conjunction with its life-saving benefits, carries a significant risk of acute brain injury (ABI). Hypoxic-ischemic brain injury (HIBI) is one of the most common types of ABI in ECMO patients. Various risk factors, such as history of hypertension, high day 1 lactate level, low pH, cannulation technique, large peri-cannulation PaCO2 drop (∆PaCO2), and early low pulse pressure, have been associated with the development of HIBI in ECMO patients. The pathogenic mechanisms of HIBI in ECMO are complex and multifactorial, attributing to the underlying pathology requiring initiation of ECMO and the risk of HIBI associated with ECMO itself. HIBI is likely to occur in the peri-cannulation or peri-decannulation time secondary to underlying refractory cardiopulmonary failure before or after ECMO. Current therapeutics target pathological mechanisms, cerebral hypoxia and ischemia, by employing targeted temperature management in the case of extracorporeal cardiopulmonary resuscitation (eCPR), and optimizing cerebral O2 saturations and cerebral perfusion. This review describes the pathophysiology, neuromonitoring, and therapeutic techniques to improve neurological outcomes in ECMO patients in order to prevent and minimize the morbidity of HIBI. Further studies aimed at standardizing the most relevant neuromonitoring techniques, optimizing cerebral perfusion, and minimizing the severity of HIBI once it occurs will improve long-term neurological outcomes in ECMO patients.

Neurologic Complications of Critical Medical Illness

OBJECTIVE

This article reviews the neurologic complications encountered in patients admitted to non-neurologic intensive care units, outlines various scenarios in which a neurologic consultation can add to the diagnosis or management of a critically ill patient, and provides advice on the best diagnostic approach in the evaluation of these patients.

LATEST DEVELOPMENTS

Increasing recognition of neurologic complications and their adverse impact on long-term outcomes has led to increased neurology involvement in non-neurologic intensive care units. The COVID-19 pandemic has highlighted the importance of having a structured clinical approach to neurologic complications of critical illness as well as the critical care management of patients with chronic neurologic disabilities.

ESSENTIAL POINTS

Critical illness is often accompanied by neurologic complications. Neurologists need to be aware of the unique needs of critically ill patients, especially the nuances of the neurologic examination, challenges in diagnostic testing, and neuropharmacologic aspects of commonly used medications.

Cerebral Neural Changes in Venous-Arterial Extracorporeal Membrane Oxygenation Survivors

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is used as temporary cardiorespiratory support in patients with critical ailments, but very little is known about the functional cerebral changes in ECMO survivors. Degree centrality (DC), a graph-based assessment of network organization, was performed to explore the neural connectivity changes in ECMO survivors compared to controls and their correlation with cognitive and neurological measures.

METHODS

This exploratory observational study was conducted from August 2020 to May 2022. ECMO survivors and controls underwent functional magnetic resonance imaging (fMRI) of the brain. We performed DC analysis to identify voxels that showed changes in whole-brain functional connectivity with other voxels. DC was measured by the fMRI graph method and comparisons between the two groups were performed. All participants underwent neuropsychological assessment (Montreal Cognitive Assessment, MoCA). Blood serum neuron-specific enolase and the Glasgow Coma Scale (GCS) were assessed in ECMO survivors.

RESULTS

DC values in the right insula and right precuneus gyrus were lower in ECMO survivors and higher in the right medial superior frontal gyrus compared to controls (all p < 0.001). Decreased connectivity in the right insular and right precuneus gyrus correlated with total MoCA scores, delayed recollection, and calculation (all p < 0.05). Increased serum NSE levels, GCS score, and GCS-motor response correlated with decreased connectivity in the right insular and right precuneus gyrus and increased connectivity in the right medial superior frontal gyrus (all p < 0.05).

CONCLUSIONS

We showed that both functional impairment and adaptation were observed in survivors of ECMO, suggesting that neural connectivity changes may provide insights into the mechanisms that may potentially link ECMO survivors to neurological and cognitive disorders.

Neurologic Complications of Patients With COVID-19 Requiring Extracorporeal Membrane Oxygenation: A Systematic Review and Meta-Analysis

In COVID-19 patients requiring extracorporeal membrane oxygenation (ECMO), our primary objective was to determine the frequency of intracranial hemorrhage (ICH). Secondary objectives were to estimate the frequency of ischemic stroke, to explore association between higher anticoagulation targets and ICH, and to estimate the association between neurologic complications and in-hospital mortality.

DATA SOURCES

We searched MEDLINE, Embase, PsycINFO, Cochrane, and MedRxiv databases from inception to March 15, 2022.

STUDY SELECTION

We identified studies that described acute neurological complications in adult patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection requiring ECMO.

DATA EXTRACTION

Two authors independently performed study selection and data extraction. Studies with 95% or more of its patients on venovenous or venoarterial ECMO were pooled for meta-analysis, which was calculated using a random-effects model.

DATA SYNTHESIS

Fifty-four studies (n = 3,347) were included in the systematic review. Venovenous ECMO was used in 97% of patients. Meta-analysis of ICH and ischemic stroke on venovenous ECMO included 18 and 11 studies, respectively. The frequency of ICH was 11% (95% CI, 8-15%), with intraparenchymal hemorrhage being the most common subtype (73%), while the frequency of ischemic strokes was 2% (95% CI, 1-3%). Higher anticoagulation targets were not associated with increased frequency of ICH (p = 0.06). In-hospital mortality was 37% (95% CI, 34-40%) and neurologic causes ranked as the third most common cause of death. The risk ratio of mortality in COVID-19 patients with neurologic complications on venovenous ECMO compared with patients without neurologic complications was 2.24 (95% CI, 1.46-3.46). There were insufficient studies for meta-analysis of COVID-19 patients on venoarterial ECMO.

CONCLUSIONS

COVID-19 patients requiring venovenous ECMO have a high frequency of ICH, and the development of neurologic complications more than doubled the risk of death. Healthcare providers should be aware of these increased risks and maintain a high index of suspicion for ICH.

Extracorporeal Membrane Oxygenation During Pregnancy

In the last 2 decades, the use of venovenous (VV) and venoarterial (VA) extracorporeal membrane oxygenation (ECMO) during pregnancy and the postpartum period has increased, mirroring the increased utilization in nonpregnant individuals worldwide. VV ECMO provides respiratory support for patients with acute respiratory distress syndrome (ARDS) who fail conventional mechanical ventilation. With the COVID-19 pandemic, the use of VV ECMO has increased dramatically and data during pregnancy and the postpartum period are overall reassuring. In contrast, VA ECMO provides both respiratory and cardiovascular support. Data on the use of VA ECMO during pregnancy are extremely limited.

Seizures in children undergoing extracorporeal membrane oxygenation: a systematic review and meta-analysis

OBJECTIVES

To investigate the incidence of seizures and short-term mortality associated with seizures in children undergoing extracorporeal membrane oxygenation (ECMO).

METHODS

PubMed, Embase, and Web of Science were searched from inception to September 2021. Study quality was assessed using the Newcastle-Ottawa Scale. Random effects meta-analysis was conducted.

RESULTS

Fourteen studies met the inclusion criteria for quantitative meta-analysis. The cumulative estimate of seizure incidence was 15% (95% CI: 12-17%). Studies using electroencephalography reported a higher incidence of seizures compared with those using electro-clinical criteria (19% vs. 9%, P = 0.034). Furthermore, 75% of seizures were subclinical. Children receiving extracorporeal cardiopulmonary resuscitation (ECPR) exhibited a higher incidence of seizures compared to children with respiratory and cardiac indications. Seizure incidence was higher in patients undergoing venoarterial (VA) ECMO compared with venovenous (VV) ECMO. The pooled odds ratio of mortality was 2.58 (95% CI: 2.25-2.95) in those developed seizures.

CONCLUSION

The incidence of seizures in children requiring ECMO was 15% and majority of seizures were subclinical. The incidence of seizures was higher in patients receiving ECPR than in those with respiratory and cardiac indications. Seizures were more frequent in patients undergoing VA ECMO than VV ECMO. Seizures were associated with increased short-term mortality.

IMPACT

The incidence of seizures in children undergoing extracorporeal membrane oxygenation (ECMO) was ~15% and majority of the seizures were subclinical. Seizures were associated with increased short-term mortality. Risk factors for seizures were extracorporeal cardiopulmonary resuscitation and venoarterial ECMO. Electroencephalography (EEG) monitoring is recommended in children undergoing ECMO and further studies on the optimal protocol for EEG monitoring are necessary.

Surgical Science and the Evolution of Critical Care Medicine

Surgical science has driven innovation and inquiry across adult and pediatric disciplines that provide critical care regardless of location. Surgically originated but broadly applicable knowledge has been globally shared within the pages Critical Care Medicine over the last 50 years.

Prevalence of hematologic complications on extracorporeal membranous oxygenation in critically ill pediatric patients: A systematic review and meta-analysis

OBJECTIVES

Despite advances in Extracorporeal Membranous Oxygenation (ECMO) equipment, hematologic complications remain significant in critically ill children. The aim of this study is to summarize prevalence of hematologic complications for children and neonates.

METHODS

MEDLINE, PubMed and Scopus databases were searched focusing on the period from January 01, 2017 to October 01, 2022. The population included critically ill children and neonates with hematologic complications. The review included all aspects of related complications including hemorrhage, thrombosis, and hemolysis. We performed random effects meta-analyses. The primary outcome measure was overall hematologic complications. Secondary outcomes are changes in the prevalence of hemorrhagic complications. Risk of bias of included studies was assessed using the Joanna Briggs Institute checklist.

RESULTS

The systematic search identified 37 studies totaling 10,659 critically ill pediatric patients receiving ECMO. The pooled prevalence of hemorrhagic complications, thrombotic complications and hemolysis among pediatric patients requiring ECMO was 43.7 % (95 % CI: 28.6 % to 58.9 %, P < 0.001), 27.6 % (95 % CI: 20.4 % to 34.8 %, P < 0.001), 34.3 % (95 % CI: 22.9 % to 45.7 %, P < 0.001). The prevalence of hemorrhagic complications was represented in descending order: surgical site (21.6 %, 95 % CI: 10.3 % to 32.9 %); cannulation site (20.6 %, 95 % CI: 11.8 % to 29.3 %); intracranial (12.2 %, 95 % CI: 9.5 % to 15.0 %); pulmonary (7.7 %, 95 % CI: 5.9 % to 9.6 %); gastrointestinal (6.0 %, 3.7 % to 8.4 %). For the assessment of thrombotic complications, thrombosis in cannulation site had a higher prevalence (28.5 %, 95 % CI: 22.1 % to 34.9 %), followed by DIC (13.5 %, 95 % CI: 8.7 % to 18.3 %) and intracranial thrombosis (4.5 %, 95 % CI: 1.4 % to 7.6 %). Predictors of increased prevalence of hemorrhagic complications included age (P = 0.017) and VV-ECMO support mode (P = 0.029).

CONCLUSIONS

Among critically ill pediatric patients, there was a series of hematologic complications can occur during ECMO support. Physicians should pay special attention to the management and establish appropriate treatment programs to reduce the occurrence of hematologic complications.

Extracorporeal Support for Acute Respiratory Distress Syndrome in Adults

Extracorporeal Support for ARDS in AdultsThere is a subset of patients who develop severe ARDS for whom supportive care with mechanical ventilation is insufficient or possibly injurious. The use of ECMO as an adjunct to treat these patients is reviewed.

Effect of Initial Anticoagulation Targets on Bleeding and Thrombotic Complications for Patients With Acute Respiratory Distress Syndrome Receiving Extracorporeal Membrane Oxygenation

OBJECTIVE

To evaluate the effect of anticoagulation targets and intensity on bleeding events, thrombotic events, and transfusion requirements in patients with acute respiratory distress syndrome (ARDS) receiving venovenous extracorporeal membrane oxygenation (ECMO) and continuous-infusion heparin.

DESIGN

A retrospective cohort study.

SETTING

At a single-center, large academic medical center.

PARTICIPANTS

One hundred thirty-six critically ill patients.

INTERVENTIONS

The following three therapeutic targets were implemented over time and evaluated: (1) no protocol (September 2013-August 2016): no standardized anticoagulation protocol or transfusion thresholds; (2) <50 seconds (September 2016-January 2018): standardized activated partial thromboplastin time (aPTT) goal of <50 seconds, maximum heparin infusion rate of 1,200 units/h, transfusion threshold of hemoglobin (Hgb) <8 g/dL; and (3) 40-to-50 seconds (February 2018-December 2019): aPTT goal of 40-to-50 sec, no maximum heparin infusion rate, transfusion threshold of Hgb <7 g/dL.

MEASUREMENTS AND MAIN RESULTS

Continuous variables were compared using the Kruskal-Wallis test, and categorical variables were compared using Fisher exact tests. The primary endpoint, an incidence of at least 1 bleeding event, was highest in the no-protocol group though not statistically different among groups (39.3% v 26.7% v 34%, p = 0.5). Thrombotic complications were similar. The median units of packed red blood cells transfused were highest in the no-protocol group (3 v 2 v 0.5, p < 0.001).

CONCLUSION

Anticoagulation protocols standardizing aPTT goals to <50 or 40-to-50 seconds may be a reasonable strategy for patients receiving venovenous ECMO for ARDS. More restrictive hemoglobin transfusion thresholds, in combination with lower aPTT targets, may be associated with a reduction in transfusion requirements.

High incidence of epileptiform activity in adults undergoing extracorporeal membrane oxygenation

OBJECTIVE

The prevalence of seizures and other types of epileptiform brain activity in patients undergoing extracorporeal membrane oxygenation (ECMO) is unknown. We aimed to estimate the prevalence of seizures and ictal-interictal continuum patterns in patients undergoing electroencephalography (EEG) during ECMO.

METHODS

Retrospective review of a prospective ECMO registry from 2011-2018 in a university-affiliated academic hospital. Adult subjects who had decreased level of consciousness and underwent EEG monitoring for seizure screening were included. EEG classification followed the American Clinical Neurophysiology Society criteria. Poor neurological outcome was defined as a Cerebral Performance Category of 3-5 at hospital discharge.

RESULTS

Three hundred and ninety-five subjects had ECMO, and one hundred and thirteen (28.6%) had EEG monitoring. Ninety-two (23.3%) subjects had EEG performed during ECMO and were included in the study (average EEG duration 54 h). Veno-arterial ECMO was the most common cannulation strategy (83%) and 26 (28%) subjects had extracorporeal cardiopulmonary resuscitation. Fifty-eight subjects (63%) had epileptiform activity or ictal-interictal continuum patterns on EEG, including three (3%) subjects with nonconvulsive status epilepticus, 33 (36%) generalized periodic discharges, and 4 (5%) lateralized periodic discharges. Comparison between subjects with or without epileptiform activity showed comparable in-hospital mortality (57% vs. 47%, p = 0.38) and poor neurological outcome (and 56% and 36%, p = 0.23). Twenty-seven subjects (33%) had acute neuroimaging abnormalities (stroke N = 21).

CONCLUSIONS

Seizures and ictal-interictal continuum patterns are commonly observed in patients managed with ECMO. Further studies are needed to evaluate whether epileptiform activity is an actionable target for interventions.

SIGNIFICANCE

Epileptiform and ictal-interictal continuum abnormalities are frequently observed in patients supported with ECMO undergoing EEG monitoring.

Assessing the SAfety and FEasibility of bedside portable low-field brain Magnetic Resonance Imaging in patients on ECMO (SAFE-MRI ECMO study): study protocol and first case series experience

BACKGROUND

To assess the safety and feasibility of imaging of the brain with a point-of-care (POC) magnetic resonance imaging (MRI) system in patients on extracorporeal membrane oxygenation (ECMO). Early detection of acute brain injury (ABI) is critical in improving survival for patients with ECMO support.

METHODS

Patients from a single tertiary academic ECMO center who underwent head CT (HCT), followed by POC brain MRI examinations within 24 h following HCT while on ECMO. Primary outcomes were safety and feasibility, defined as completion of MRI examination without serious adverse events (SAEs). Secondary outcome was the quality of MR images in assessing ABIs.

RESULTS

We report 3 consecutive adult patients (median age 47 years; 67% male) with veno-arterial (n = 1) and veno-venous ECMO (n = 2) (VA- and VV-ECMO) support. All patients were imaged successfully without SAEs. Times to complete POC brain MRI examinations were 34, 40, and 43 min. Two patients had ECMO suction events, resolved with fluid and repositioning. Two patients were found to have an unsuspected acute stroke, well visualized with MRI.

CONCLUSIONS

Adult patients with VA- or VV-ECMO support can be safely imaged with low-field POC brain MRI in the intensive care unit, allowing for the assessment of presence and timing of ABI.

Cerebral Blood Flow Hemispheric Asymmetry in Comatose Adults Receiving Extracorporeal Membrane Oxygenation

Peripheral veno-arterial extracorporeal membrane oxygenation (ECMO) artificially oxygenates and circulates blood retrograde from the femoral artery, potentially exposing the brain to asymmetric perfusion. Though ECMO patients frequently experience brain injury, neurologic exams and imaging are difficult to obtain. Diffuse correlation spectroscopy (DCS) non-invasively measures relative cerebral blood flow (rBF) at the bedside using an optical probe on each side of the forehead. In this study we observed interhemispheric rBF differences in response to mean arterial pressure (MAP) changes in adult ECMO recipients. We recruited 13 subjects aged 21–78 years (7 with cardiac arrest, 4 with acute heart failure, and 2 with acute respiratory distress syndrome). They were dichotomized via Glasgow Coma Scale Motor score (GCS-M) into comatose (GCS-M ≤ 4; n = 4) and non-comatose (GCS-M > 4; n = 9) groups. Comatose patients had greater interhemispheric rBF asymmetry (ASYM_rBF) vs. non-comatose patients over a range of MAP values (29 vs. 11%, p = 0.009). ASYM_rBF in comatose patients resolved near a MAP range of 70–80 mmHg, while rBF remained symmetric through a wider MAP range in non-comatose patients. Correlations between post-oxygenator pCO₂ or pH vs. ASYM_rBF were significantly different between comatose and non-comatose groups. Our findings indicate that comatose patients are more likely to have asymmetric cerebral perfusion.

Neurological Complications in COVID-19 Patients With ECMO Support: A Systematic Review and Meta-Analysis

BACKGROUND

Patients with Coronavirus disease 2019 (COVID-19)-related acute respiratory disease (ARDS) increasingly receive extracorporeal membrane oxygenation (ECMO) support. While ECMO has been shown to increase risk of stroke, few studies have examined this association in COVID-19 patients.

OBJECTIVE

We conducted a systematic review to characterise neurological events during ECMO support in COVID-19 patients.

DESIGN

Systematic review of cohort and large case series of COVID-19 patients who received ECMO support.

DATA SOURCES

Studies retrieved from PubMed, EMBASE, Cochrane, Cochrane COVID-19 Study Register, Web of Science, Scopus, Clinicaltrials.gov, and medRχiv from inception to November 11, 2020.

ELIGIBILITY CRITERIA

Inclusion criteria were a) Adult population (>18 year old); b) Positive PCR test for SARS-CoV-2 with active COVID-19 disease; c) ECMO therapy due to COVID-19 ARDS; and d) Neurological events and outcome described while on ECMO support. We excluded articles when no details of neurologic events were available.

RESULTS

1,322 patients from 12 case series and retrospective cohort studies were included in our study. The median age was 49.2, and 75% (n=985) of the patients were male. Diabetes mellitus and dyslipidaemia were the most common comorbidities (24% and 20%, respectively). Most (95%, n=1,241) patients were on venovenous ECMO with a median P:F ratio at the time of ECMO cannulation of 69.1. The prevalence of intracranial haemorrhage (ICH), ischaemic stroke, and hypoxic ischaemic brain injury (HIBI) was 5.9% (n=78), 1.1% (n=15), and 0.3% (n=4), respectively. The overall mortality of the 1,296 ECMO patients in the 10 studies that reported death was 36% (n=477), and the mortality of the subset of patients who had a neurological event was 92%.

CONCLUSIONS

Neurological injury is a concern for COVID-19 patients who receive ECMO. Further research is required to explore how neuromonitoring protocols can inform tailored anticoagulation management and improve survival in COVID-19 patients with ECMO support.

Association of COVID-19 with Intracranial Hemorrhage during Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome: A 10-Year Retrospective Observational Study

Extracorporeal membrane oxygenation (ECMO) is potentially lifesaving for patients with acute respiratory distress syndrome (ARDS) but may be accompanied by serious adverse events, including intracranial hemorrhage (ICRH). We hypothesized that ICRH occurs more frequently in patients with COVID-19 than in patients with ARDS of other etiologies. We performed a single-center retrospective analysis of adult patients treated with venovenous (vv-) ECMO for ARDS between January 2011 and April 2021. Patients were included if they had received a cranial computed tomography (cCT) scan during vv-ECMO support or within 72 h after ECMO removal. Cox regression analysis was used to identify factors associated with ICRH. During the study period, we identified 204 patients with vv-ECMO for ARDS, for whom a cCT scan was available. We observed ICRH in 35.4% (n = 17/48) of patients with COVID-19 and in 16.7% (n = 26/156) of patients with ARDS attributable to factors other than COVID-19. COVID-19 (HR: 2.945; 95%; CI: 1.079–8.038; p = 0.035) and carboxyhemoglobin (HR: 0.330; 95%; CI: 0.135–0.806; p = 0.015) were associated with ICRH during vv-ECMO. In patients receiving vv-ECMO, the incidence of ICRH is doubled in patients with COVID-19 compared to patients suffering from ARDS attributable to other causes. More studies on the association between COVID-19 and ICRH during vv-ECMO are urgently needed to identify risk patterns and targets for potential therapeutic interventions.

Narrative Review of Neurologic Complications in Adults on ECMO: Prevalence, Risks, Outcomes, and Prevention Strategies

Extracorporeal membrane oxygenation (ECMO), a life-saving technique for patients with severe respiratory and cardiac diseases, is being increasingly utilized worldwide, particularly during the coronavirus disease 2019(COVID-19) pandemic, and there has been a sharp increase in the implementation of ECMO. However, due to the presence of various complications, the survival rate of patients undergoing ECMO remains low. Among the complications, the neurologic morbidity significantly associated with venoarterial and venovenous ECMO has received increasing attention. Generally, failure to recognize neurologic injury in time is reportedly associated with poor outcomes in patients on ECMO. Currently, multimodal monitoring is increasingly utilized in patients with devastating neurologic injuries and has been advocated as an important approach for early diagnosis. Here, we highlight the prevalence and outcomes, risk factors, current monitoring technologies, prevention, and treatment of neurologic complications in adult patients on ECMO. We believe that an improved understanding of neurologic complications presumably offers promising therapeutic solutions to prevent and treat neurologic morbidity.

Neurocritical Care of Mechanical Circulatory Support Devices

PURPOSE OF REVIEW

Mechanical circulatory support (MCS) devices have demonstrated improved survival outcomes in otherwise refractory cardiopulmonary failure but are associated with significant neurologic morbidity and mortality. This review aims to characterize MCS-associated brain injury and discuss the neurocritical care of this population.

RECENT FINDINGS

We found no practice guidelines or specific management strategies for the neurocritical care of patients with MCS devices. Acute brain injury was commonly observed in short-term and durable MCS devices. There is emerging evidence that a standardized neurological monitoring and management algorithm for MCS device-associated brain injury is feasible and potentially improves neurological outcomes. While MCS devices are associated with significant neurologic morbidity and mortality, there is scant evidence regarding optimal neuromonitoring and neurocritical care. With the increase in use of MCS devices for both short-term and durable applications, improved outcomes will depend on early identification and intervention of neurologic complications and further research into their pathophysiology.