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

Association Between Cerebral Microbleeds and Neurological Outcomes in Patients Who Underwent Extracorporeal Membrane Oxygenation

BACKGROUND

Cerebral microbleeds (CMBs) are common and varied in patients receiving extracorporeal membrane oxygenation (ECMO). Here, the authors describe CMB findings in patients receiving ECMO and their association with clinical factors.

METHODS AND RESULTS

A total of 138 patients receiving ECMO were enrolled and categorized as venovenous and venoarterial. Blood coagulation profiles during ECMO support and Glasgow Coma Scale (GCS) scores within 7 days were recorded. Patients with CMBs exhibited prolonged activated clotting time (P<0.001), decreased fibrinogen levels (P<0.001), reduced platelet counts (P<0.001), and extended prothrombin time (P<0.001). A significant correlation (P<0.05) was observed between the presence of CMBs and most coagulation parameters among all patients. Patients with venoarterial ECMO had significantly higher activated partial thromboplastin time, activated clotting time, and prothrombin time compared with those with venovenous ECMO (all P<0.05). Patients with a less severe CMB burden exhibited higher GCS scores and better neurological injury outcomes at both 7 and 90 days. CMB burden in all patients with ECMO was significantly correlated (P<0.05) with most blood coagulation profiles and neurological injury.

CONCLUSIONS

CMB burdens after ECMO are common, varied, and associated with a variety of clinical conditions. These findings may guide ECMO management.

Acute Ischemic Stroke during Extracorporeal Membrane Oxygenation (ECMO): A Narrative Review of the Literature

Ischemic stroke (IS) is a severe complication and leading cause of mortality in patients under extracorporeal membrane oxygenation (ECMO). The aim of our narrative review is to summarize the existing evidence and provide a deep examination of the diagnosis and treatment of acute ischemic stroke patients undergoing ECMO support. The incidence rate of ISs is estimated to be between 1 and 8%, while the mortality rate ranges from 44 to 76%, depending on several factors, including ECMO type, duration of support and patient characteristics. Several mechanisms leading to ISs during ECMO have been identified, with thromboembolic events and cerebral hypoperfusion being the most common causes. However, considering that most of the ECMO patients are severely ill or under sedation, stroke symptoms are often underdiagnosed. Multimodal monitoring and daily clinical assessment could be useful preventive techniques. Early recognition of neurological deficits is of paramount importance for prompt therapeutic interventions. All ECMO patients with suspected strokes should immediately receive brain computed tomography (CT) and CT angiography (CTA) for the identification of large vessel occlusion (LVO) and assessment of collateral blood flow. CT perfusion (CTP) can further assist in the detection of viable tissue (penumbra), especially in cases of strokes of unknown onset. Catheter angiography is required to confirm LVO detected on CTA. Intravenous thrombolytic therapy is usually contraindicated in ECMO as most patients are on active anticoagulation treatment. Therefore, mechanical thrombectomy is the preferred treatment option in cases where there is evidence of LVO. The choice of the arterial vascular access used to perform mechanical thrombectomy should be discussed between interventional radiologists and an ECMO team. Anticoagulation management during the acute phase of IS should be individualized after the thromboembolic risk has been carefully balanced against hemorrhagic risk. A multidisciplinary approach is essential for the optimal management of ISs in patients treated with ECMO.

Short-Term Neurologic Complications in Patients Undergoing Extracorporeal Membrane Oxygenation Support: A Review on Pathophysiology, Incidence, Risk Factors, and Outcomes

Regardless of the type, extracorporeal membrane oxygenation (ECMO) requires the use of large intravascular cannulas and results in multiple abnormalities including non-physiologic blood flow, hemodynamic perturbation, rapid changes in blood oxygen and carbon dioxide levels, coagulation abnormalities, and a significant systemic inflammatory response. Among other sequelae, neurologic complications are an important source of mortality and long-term morbidity. The frequency of neurologic complications varies and is likely underreported due to the high mortality rate. Neurologic complications in patients supported by ECMO include ischemic and hemorrhagic stroke, hypoxic brain injury, intracranial hemorrhage, and brain death. In addition to the disease process that necessitates ECMO, cannulation strategies and physiologic disturbances influence neurologic outcomes in this high-risk population. For example, the overall documented rate of neurologic complications in the venovenous ECMO population is lower, but a higher rate of intracranial hemorrhage exists. Meanwhile, in the venoarterial ECMO population, ischemia and global hypoperfusion seem to compose a higher percentage of neurologic complications. In what follows, the literature is reviewed to discuss the pathophysiology, incidence, risk factors, and outcomes related to short-term neurologic complications in patients supported by ECMO.

Device associated complications in the intensive care unit

Invasive devices are routinely used in the care of critically ill patients. Although they are often essential components of patient care, devices such as intravascular catheters, endotracheal tubes, and ventilators are a common source of complications in the intensive care unit. Critical care practitioners who use these devices need to use strategies for risk reduction and understand approaches to management when adverse events occur. This review discusses the identification, prevention, and management of complications of vascular, airway, and mechanical support devices commonly used in the intensive care unit.

Machine Learning from Veno-Venous Extracorporeal Membrane Oxygenation Identifies Factors Associated with Neurological Outcomes

BACKGROUND

Neurological complications are common in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO) support. We used machine learning (ML) algorithms to identify predictors for neurological outcomes for these patients.

METHODS

All demographic, clinical, and circuit-related variables were extracted for adults with VV-ECMO support at a tertiary care center from 2016 to 2022. The primary outcome was good neurological outcome (GNO) at discharge defined as a modified Rankin Scale of 0-3.

RESULTS

Of 99 total VV-ECMO patients (median age = 48 years; 65% male), 37% had a GNO. The best performing ML model achieved an area under the receiver operating characteristic curve of 0.87. Feature importance analysis identified down-trending gas/sweep/blender flow, FiO2, and pump speed as the most salient features for predicting GNO.

CONCLUSION

Utilizing pre- as well as post-initiation variables, ML identified on-ECMO physiologic and pulmonary conditions that best predicted neurological outcomes.

Extracorporeal Membrane Oxygenation for Respiratory Failure: A Narrative Review

Extracorporeal membrane oxygenation support for respiratory failure in the intensive care unit continues to have an expanded role in select patients. While acute respiratory distress syndrome remains the most common indication, extracorporeal membrane oxygenation may be used in other causes of refractory hypoxemia and/or hypercapnia. The most common configuration is veno-venous extracorporeal membrane oxygenation; however, in specific cases of refractory hypoxemia or right ventricular failure, some patients may benefit from veno-pulmonary extracorporeal membrane oxygenation or veno-venoarterial extracorporeal membrane oxygenation. Patient selection and extracorporeal circuit management are essential to successful outcomes. This narrative review explores the physiology of extracorporeal membrane oxygenation, indications and contraindications, ventilator management, extracorporeal circuit management, troubleshooting hypoxemia, complications, and extracorporeal membrane oxygenation weaning in patients with respiratory failure. As the footprint of extracorporeal membrane oxygenation continues to expand, it is essential that clinicians understand the underlying physiology and management of these complex patients.

Multimodal Neurologic Monitoring in Patients Undergoing Extracorporeal Membrane Oxygenation

Introduction Extracorporeal membrane oxygenation (ECMO) is associated with a high rate of neurologic complications. Multimodal neurologic monitoring (MNM) has the potential for early detection and intervention. We examined the safety and feasibility of noninvasive MNM during ECMO. We hypothesized that survivors and non-survivors would have meaningful differences in transcranial Doppler (TCD) sonography and electroencephalographic (EEG) characteristics, which we aimed to identify. We also investigated adverse neurologic events and attempted to identify differences in EEG and TCD characteristics among patients based on the type of ECMO and the occurrence of these events. Material and methods We performed an observational study on all patients undergoing ECMO at Baylor St. Luke's Medical Center's critical care unit in Houston, Texas, United States, from January 2017 to February 2019. All patients underwent a noninvasive MNM protocol. Results NM was completed in 75% of patients; all patients received at least one component of the monitoring protocol. No adverse events were noted, showing the feasibility and safety of the protocol. The 60.4% of patients who did not survive tended to be older, had lower ejection fractions, and had lower median right middle cerebral artery (MCA) pulsatility and resistivity indexes. Patients undergoing venoarterial (VA)-ECMO had lower median left and right MCA velocities and lower right Lindegaard ratios than patients who underwent venovenous-ECMO. In VA-ECMO patients, EEG less often showed sleep architecture, while other findings were similar between groups. Adverse neurologic events occurred in 24.7% of patients, all undergoing VA-ECMO. Acute ischemic stroke occurred in 22% of patients, intraparenchymal hemorrhage in 4.9%, hypoxic-ischemic encephalopathy in 3.7%, subarachnoid hemorrhage in 2.5%, and subdural hematoma in 1.2%. Conclusion Our results suggest that MNM is safe and feasible for patients undergoing ECMO. Certain EEG and TCD findings could aid in the early detection of neurologic deterioration. MNM may not just be used in monitoring patients undergoing ECMO but also in prognostication and aiding clinical decision-making.

Psychological experiences of patients recovering from severe COVID-19 in rehabilitation: A qualitative study

The aim of this study was to describe the experiences of post-sedation COVID-19 patients in rehabilitation. Eleven Israeli men and women were interviewed in semi-structured interviews. They were patients recovering in a neurological rehabilitation unit from severe COVID-19 post-mechanical ventilation and sedation. Five themes were generated through thematic analysis: "an unexpected turn of events," "filling the gaps," "emotional reactions," "ambiguity regarding medical condition," and "sense and meaning-making." Findings suggest a need for improved communication between patients and medical staff to enhance a sense of control and coherence. Psychological support should be considered to facilitate sense and meaning-making processes during hospitalization.

Use of extracorporeal membrane oxygenation in children with burn injury: Case report and literature review

RATIONALE

Burns are one of the most debilitating injuries in the world and one of the major causes of accidental disability and death among children. Severe burns can result in irreversible brain damage, placing patients at high risk of brain failure and high mortality. Therefore, timely diagnosis and treatment of burn encephalopathy are crucial for improving prognosis. In recent years, extracorporeal membrane oxygenation (ECMO) has been increasingly used to improve the prognosis of patients with burns. Here, we report a case of ECMO treatment in a child with burns and review the relevant literature.

PATIENT CONCERNS

A 7-year-old boy with a modified Baux score of 24 presented with asphyxia, loss of consciousness, refractory hypoxemia, and malignant arrhythmia after smoke inhalation for 1 day. Fiberoptic bronchoscopy revealed a large amount of black carbon-like substances aspirated from the trachea.

DIAGNOSES

Considering that the boy inhaled a large amount of smoke, the clinical manifestation was unclear consciousness, laboratory examination revealed continuous low blood oxygen saturation, and bronchoscopy revealed a large amount of black carbon-like substances in the trachea, thereby leading to the diagnosis of asphyxia, inhalation pneumonia, burn encephalopathy, multiple organ dysfunction syndrome, and malignant arrhythmia. In addition, pulmonary edema and carbon monoxide poisoning are caused by chemical agents, gas fumes, and vapors.

INTERVENTIONS

The boy's blood oxygen saturation and blood circulation remained unstable despite various ventilation methods and medications, thus we decided to use ECMO. After 8 days of ECMO support, the patient was successfully weaned from the machine.

OUTCOMES

Under the application of ECMO, the respiratory and circulatory systems significantly improved. Nevertheless, due to the progressive brain injury caused by burns and the poor prognosis, the parents ceased all treatment and the boy passed away.

LESSONS

This case report demonstrates that brain edema and herniation can arise as phenotypes of burn encephalopathy, which is a challenge to treat in children. Children with confirmed or suspected burn encephalopathy should undergo diagnostic tests completed as soon as possible to confirm the diagnosis. After receiving ECMO treatment, the respiratory and circulatory systems of the burn victims reported significantly improved. Hence, ECMO is a viable alternative for supporting patients with burns.

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.

Utilization and Outcomes of Extracorporeal Membrane Oxygenation Following Traumatic Brain Injury in the United States

Objectives: Describe contemporary ECMO utilization patterns among patients with traumatic brain injury (TBI) and examine clinical outcomes among TBI patients requiring ECMO. Design: Retrospective cohort study. Setting: Premier Healthcare Database (PHD) between January 2016 to June 2020. Subjects: Adult patients with TBI who were mechanically ventilated and stratified by exposure to ECMO. Results: Among patients exposed to ECMO, we examined the following clinical outcomes: hospital LOS, ICU LOS, duration of mechanical ventilation, and hospital mortality. Of our initial cohort (n = 59,612), 118 patients (0.2%) were placed on ECMO during hospitalization. Most patients were placed on ECMO within the first 2 days of admission (54.3%). Factors associated with ECMO utilization included younger age (OR 0.96, 95% CI (0.95–0.97)), higher injury severity score (ISS) (OR 1.03, 95% CI (1.01–1.04)), vasopressor utilization (2.92, 95% CI (1.90–4.48)), tranexamic acid utilization (OR 1.84, 95% CI (1.12–3.04)), baseline comorbidities (OR 1.06, 95% CI (1.03–1.09)), and care in a teaching hospital (OR 3.04, 95% CI 1.31–7.05). A moderate degree (ICC = 19.5%) of variation in ECMO use was explained at the individual hospital level. Patients exposed to ECMO had longer median (IQR) hospital and ICU length of stay (LOS) [26 days (11–36) versus 9 days (4–8) and 19.5 days (8–32) versus 5 days (2–11), respectively] and a longer median (IQR) duration of mechanical ventilation [18 days (8–31) versus 3 days (2–8)]. Patients exposed to ECMO experienced a hospital mortality rate of 33.9%, compared to 21.2% of TBI patients unexposed to ECMO. Conclusions: ECMO utilization in mechanically ventilated patients with TBI is rare, with significant variation across hospitals. The impact of ECMO on healthcare utilization and hospital mortality following TBI is comparable to non-TBI conditions requiring ECMO. Further research is necessary to better understand the role of ECMO following TBI and identify patients who may benefit from this therapy.

Perspectives: Regional brain oxygen saturation: beyond the brain there is also life

Abstract:

Some procedures, such as cardiovascular surgery, may compromise brain perfusion and require careful management to preserve the integrity of the central nervous system. In this setting, regional cerebral oxygen saturation [rSO2] emerges as an alternative, minimally invasive, monitoring system. The mechanism by which regional oxygen is measured is based on the refraction and absorption of a signal with a specific wavelength. Diagnostic and therapeutic algorithms for these settings. This would allow for a more rational use of goal-directed therapies that reduce morbidity and mortality in these patients.