BACKGROUND: Early detection of acute brain injury (ABI) at the bedside is critical in improving survival for patients with extracorporeal membrane oxygenation (ECMO) support. We aimed to examine the safety of ultra–low-field (ULF; 0.064-T) portable magnetic resonance imaging (pMRI) in patients undergoing ECMO and to investigate the ABI frequency and types with ULF-pMRI. METHODS: This was a multicenter prospective observational study (SAFE MRI ECMO study [Assessing the Safety and Feasibility of Bedside Portable Low-Field Brain Magnetic Resonance Imaging in Patients on ECMO]; NCT05469139) from 2 tertiary centers (Johns Hopkins, Baltimore, MD and University of Texas–Houston) with specially trained intensive care units. Primary outcomes were safety of ULF-pMRI during ECMO support, defined as completion of ULF-pMRI without significant adverse events. RESULTS: Of 53 eligible patients, 3 were not scanned because of a large head size that did not fit within the head coil. ULF-pMRI was performed in 50 patients (median age, 58 years; 52% male), with 34 patients (68%) on venoarterial ECMO and 16 patients (32%) on venovenous ECMO. Of 34 patients on venoarterial ECMO, 11 (22%) were centrally cannulated and 23 (46%) were peripherally cannulated. In venovenous ECMO, 9 (18%) had single-lumen cannulation and 7 (14%) had double-lumen cannulation. Of 50 patients, adverse events occurred in 3 patients (6%), with 2 minor adverse events (ECMO suction event; transient low ECMO flow) and one serious adverse event (intra-aortic balloon pump malfunction attributable to electrocardiographic artifacts). All images demonstrated discernible intracranial pathologies with good quality. ABI was observed in 22 patients (44%). Ischemic stroke (36%) was the most common type of ABI, followed by intracranial hemorrhage (6%) and hypoxic-ischemic brain injury (4%). Of 18 patients (36%) with both ULF-pMRI and head computed tomography within 24 hours, ABI was observed in 9 patients with a total of 10 events (8 ischemic, 2 hemorrhagic events). Of the 8 ischemic events, pMRI observed all 8, and head computed tomography observed only 4 events. For intracranial hemorrhage, pMRI observed only 1 of them, and head computed tomography observed both (2 events). CONCLUSIONS: Our study demonstrates that ULF-pMRI can be performed in patients on ECMO across different ECMO cannulation strategies in specially trained intensive care units. The incidence of ABI was high, seen in 44% of ULF-pMRI studies. ULF-pMRI imaging appears to be more sensitive to ABI, particularly ischemic stroke, compared with head computed tomography.

(1) Background: Fifty percent of patients supported on veno-arterial extracorporeal membrane oxygenation (VA-ECMO) are concurrently supported with an intra-aortic balloon pump (IABP). Acute brain injury (ABI) is a devastating complication related to ECMO and IABP use. The standard of care for ABI diagnosis requires transport to a head CT (HCT) scanner. Recent data suggest that point-of-care (POC) magnetic resonance imaging (MRI) is safe and may be effective in diagnosing ABI in ECMO patients; however, no data exist in patients supported on ECMO with an IABP. We report pre-clinical safety data and a case series to evaluate the safety and feasibility of POC brain MRI in ECMO patients supported with IABP. (2) Methods: Prior to patient use, ex vivo testing with an IABP catheter within the Swoop^® Portable MRI (0.064 T) System™ was conducted. After IRB approval, clinical testing was performed for the safety and feasibility of early ABI detection. (3) Results: No deflection force was measured with a 7.5 French Maquet Linear IABP within the 0.064 T field. Three adult ECMO patients (average age: 40 years; 67% female) supported with IABP completed four POC brain MRI exams (median exam time: 30 min). Multiple signal abnormalities were detected on the POC brain MRI, corresponding to HCT results. (4) Conclusions: Our preliminary results suggest that adult VA-ECMO patients with IABP support can be safely imaged with low-field POC brain MRI in the intensive care unit, allowing for the early and bedside imaging of patients.

Objective: We aimed to characterize the impact of body mass index (BMI) on stroke in patients receiving extracorporeal cardiopulmonary resuscitation (ECPR). Methods: We queried the Extracorporeal Life Support Organization registry for patients receiving ECPR (2020–2024). Patients were categorized into five BMI groups: underweight (<18.5 kg/m²), normal weight (18.5–24.9 kg/m²), overweight (25–29.9 kg/m²), class 1 obesity (30–34.9 kg/m²), and class 2 obesity or above (≥35 kg/m²). A generalized additive model (GAM) analysis was used to identify the BMI range with the greatest stroke risk. Multivariable regression was used to compare odds of stroke between standard BMI groups and normal weight. Propensity score matching was used to compare stroke and mortality between normal weight and the BMI group with the highest predicted stroke risk. Results: Of 6390 patients (median age = 57.5, 68.6% male), 470 (7.4%) had a stroke during ECMO support (4.5% ischemic; 3.4% hemorrhagic). A total of 9.6% (n = 131) of class 1 obesity patients experienced stroke compared with 6.6% (n = 111) of normal weight, 6.9% (n = 79) of class 2 obesity or above, 6.9% (n = 143) of overweight, and 5.4% (n = 6) of underweight patients (p = 0.01). The GAM analysis showed a highest predicted stroke risk for class 1 obesity patients (n = 1366), which was confirmed by multivariable regression (adjusted odds ratio (aOR) = 1.63, 95%CI = 1.01–2.62, p = 0.045). After propensity matching (n = 357 each), class 1 obesity was associated with ischemic (aOR = 2.01, 95%CI = 1.02–4.08, p = 0.047) but not hemorrhagic stroke. Odds of hospital mortality were higher in both class 1 and 2 obesity patients compared with normal weight. Conclusions: Class 1 obesity was associated with increased odds of ischemic but not hemorrhagic stroke compared with normal weight patients.

Background: Low pulse pressure (PP) in venoarterial-extracorporeal membrane oxygenation (VA-ECMO) is a marker of cardiac dysfunction and has been associated with acute brain injury (ABI) as continuous-flow centrifugal pump may lead to endothelial dysregulation. Methods: We retrospectively analyzed adults (≥18 years) on “peripheral” VA-ECMO support for cardiogenic shock in the Extracorporeal Life Support Organization Registry (1/2018-7/2023). Cubic splines were used to establish a threshold (PP≤10 mmHg at 24 hours of ECMO support) for “early low” PP. ABI included central nervous system (CNS) ischemia, intracranial hemorrhage, brain death, and seizures. Multivariable logistic regressions were performed to examine whether PP≤10 mmHg was associated with ABI. Covariates included age, sex, body mass index, pre-ECMO variables (temporary mechanical support, vasopressors, cardiac arrest), on-ECMO variables (pH, PaO₂, PaCO₂), and on-ECMO complications (hemolysis, arrhythmia, renal replacement therapy). Results: Of 9,807 peripheral VA-ECMO patients (median age=57.4 years, 67% male), 8,294 (85%) had PP>10 mmHg vs. 1,513 (15%) had PP≤10 mmHg. Patients with PP≤10 mmHg experienced ABI more frequently vs. PP>10 mmHg (15% vs. 11%, p10 mmHg (8% vs. 6%, p=0.008; 3% vs. 1%, p<0.001). PP≤10 mmHg was associated with CNS ischemia (aOR=1.26, 95%CI=1.02-1.56, p=0.03) but not intracranial hemorrhage (aOR=1.14, 95%CI=0.85-1.54, p=0.38). Conclusions: Early low PP (≤10 mmHg) at 24 hours of ECMO support was associated with ABI, particularly CNS ischemia, in peripheral VA-ECMO patients.

CONTEXT: Conventional MRI is incompatible with extracorporeal membrane oxygenation (ECMO) cannulas and pumps. Ultra-low-field portable MRI (ULF-pMRI) with 0.064 Tesla may provide a solution, but its safety and compatibility is unknown. HYPOTHESIS: ULF-pMRI does not cause significant displacement and heating of ECMO cannulas and does not affect ECMO pump function. METHODS AND MODELS: ECMO cannulas in various sizes were tested ex vivo using phantom models to assess displacement force and heating according to the American Society for Testing and Materials criteria. ECMO pump function was assessed by pump flow and power consumption. In vivo studies involved five female domestic pigs (20–42 kg) undergoing different ECMO configurations (peripheral and central cannulation) and types of cannulas with an imaging protocol consisting of T2-weighted, T1-weighted, FLuid-Attenuated Inversion Recovery, and diffusion-weighted imaging sequences. RESULTS: Phantom models demonstrated that ECMO cannulas, both single lumen with various sizes (15–24-Fr) and double lumen cannula, had average displacement force less than gravitational force within 5 gauss safety line of ULF-pMRI and temperature changes less than 1°C over 15 minutes of scanning and ECMO pump maintained stable flow and power consumption immediately outside of the 5 gauss line. All pig models showed no visible motion due to displacement force or heating of the cannulas. ECMO flow and the animals’ hemodynamic status maintained stability, with no changes greater than 10%, respectively. INTERPRETATION AND CONCLUSIONS: ULF-pMRI is safe and feasible for use with standard ECMO configurations, supporting its clinical application as a neuroimaging modality in ECMO patients.

Importance: Skin pigmentation influences peripheral oxygen saturation (SpO₂) measured by pulse oximetry compared to the arterial saturation of oxygen (SaO₂) measured via arterial blood gas analysis. However, data on SpO₂-SaO₂ discrepancy are limited in venovenous-extracorporeal membrane oxygenation (VV-ECMO) patients. Objective: To determine whether there is racial/ethnical discrepancy between SpO₂ and SaO₂ in patients receiving VV-ECMO. We hypothesized VV-ECMO cannulation, in addition to race/ethnicity, accentuates the SpO₂-SaO₂ discrepancy due to significant hemolysis. Design: Retrospective cohort study of the Extracorporeal Life Support Organization Registry from 1/2018-5/2023. Setting: International, multicenter registry study including over 500 ECMO centers. Participants: Adults (≥ 18 years) supported with VV-ECMO with concurrently measured SpO₂ and SaO₂ measurements. Exposure: Race/ethnicity and ECMO cannulation. Main outcomes and measures: Occult hypoxemia (SaO₂ ≤ 88% with SpO₂ ≥ 92%) was our primary outcome. Multivariable logistic regressions were performed to examine whether race/ethnicity was associated with occult hypoxemia in pre-ECMO and on-ECMO SpO₂-SaO₂ calculations. Covariates included age, sex, temporary mechanical circulatory support, pre-vasopressors, and pre-inotropes for pre-ECMO analysis, plus single-lumen versus double-lumen cannulation, hemolysis, hyperbilirubinemia, ECMO pump flow rate, and on-ECMO 24h lactate for on-ECMO analysis. Results: Of 13,171 VV-ECMO patients (median age = 48.6 years, 66% male), there were 7,772 (59%) White, 2,114 (16%) Hispanic, 1,777 (14%) Black, and 1,508 (11%) Asian patients. The frequency of on-ECMO occult hypoxemia was 2.0% (N = 233). Occult hypoxemia was more common in Black and Hispanic versus White patients (3.1% versus 1.7%, P < 0.001 and 2.5% versus 1.7%, P = 0.025, respectively). In multivariable logistic regression, Black patients were at higher risk of pre-ECMO occult hypoxemia versus White patients (adjusted odds ratio [aOR] = 1.55, 95% confidence interval [CI] = 1.18–2.02, P = 0.001). For on-ECMO occult hypoxemia, Black patients (aOR = 1.79, 95%CI = 1.16–2.75, P = 0.008) and Hispanic patients (aOR = 1.71, 95%CI = 1.15–2.55, P = 0.008) had higher risk versus White patients. Furthermore, higher pump flow rate (aOR = 1.29, 95%CI = 1.08–1.55, P = 0.005) and higher on-ECMO 24h lactate (aOR = 1.06, 95%CI = 1.03–1.10, P < 0.001) significantly increased the risk of on-ECMO occult hypoxemia. Conclusions and Relevance: Hispanic and Black VV-ECMO patients experienced occult hypoxemia more than White patients. SaO₂ should be carefully monitored during ECMO support for Black and Hispanic patients especially for those with high pump flow and lactate values at risk for occult hypoxemia.