Background/Objectives Previous studies demonstrated that in older persons decline in muscle strength occurs with aging more rapidly than loss of muscle mass, highlighting the importance of muscle quality for functional outcomes in later life. We examine differences in a proxy measure of muscle quality across the adult life-span and explore potential mechanisms of muscle quality change through identification of cross-sectional correlates of muscle quality. Design Cross-sectional study. Setting/Participants 786 participants from the Baltimore Longitudinal Study of Aging (mean age 66.3 years, range: 26 – 96 years). A sensitivity analysis was conducted in a subset of participants matched by sex, muscle mass and body size. Measurements Muscle quality, was operationalized as the ratio of knee-extension strength (isokinetic dynamometry) to thigh muscle cross-sectional area (computed tomography). Trends of muscle strength, area and muscle quality ratio across age were evaluated and the association of the muscle quality ratio with measures reflecting domains of cognitive function, motor control, peripheral nerve function, adiposity, glucose homeostasis, and inflammation were assessed through multivariate regression analyses. Results A linear relationship between age and muscle quality ratio was observed suggesting gradual decline in muscle quality across the adult life course. Associations were observed between muscle quality ratio and measures of adiposity as well as peroneal nerve motor conduction velocity, finger tapping speed, memory performance (p<.01). The association of muscle quality ratio with nerve conduction velocity was maintained after adjustment for anthropometrics (p<.05). Conclusion These observations suggest that muscle quality declines progressively with aging across the adult life span and is affected by both obesity and neurological factors. Studies are needed to clarify the mechanisms of these associations and their implications for functional outcomes.

Serum antibodies develop upon infection with SARS-CoV-2 and are currently used to stratify donors of convalescent plasma and assess the prevalence of COVID-19. This study examines the use of serum antibodies to SARS-CoV-2 spike protein in the diagnosis of COVID-19.

OBJECTIVES: To evaluate the impact of duration of hyperoxia on neurologic outcome and mortality in patients undergoing venoarterial extracorporeal membrane oxygenation. DESIGN: A retrospective analysis of venoarterial extracorporeal membrane oxygenation patients admitted to the Johns Hopkins Hospital. The primary outcome was neurologic function at discharge defined by modified Rankin Scale, with a score of 0–3 defined as a good neurologic outcome, and a score of 4–6 defined as a poor neurologic outcome. Multivariable logistic regression analysis was performed to evaluate the association between hyperoxia and neurologic outcomes. SETTING: The Johns Hopkins Hospital Cardiovascular ICU and Cardiac Critical Care Unit. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We measured first and maximum Pao 2 values, area under the curve per minute over the first 24 hours, and duration of mild, moderate, and severe hyperoxia. Of 132 patients on venoarterial extracorporeal membrane oxygenation, 127 (96.5%) were exposed to mild hyperoxia in the first 24 hours. Poor neurologic outcomes were observed in 105 patients (79.6%) (102 with vs 3 without hyperoxia; p = 0.14). Patients with poor neurologic outcomes had longer exposure to mild (19.1 vs 15.2 hr; p = 0.01), moderate (14.6 vs 9.2 hr; p = 0.003), and severe hyperoxia (9.1 vs 4.0 hr; p = 0.003). In a multivariable analysis, patients with worse neurologic outcome experienced longer durations of mild (adjusted odds ratio, 1.10; 95% CI, 1.01–1.19; p = 0.02), moderate (adjusted odds ratio, 1.12; 95% CI, 1.04–1.22; p = 0.002), and severe (adjusted odds ratio, 1.19; 95% CI, 1.06–1.35; p = 0.003) hyperoxia. Additionally, duration of severe hyperoxia was independently associated with inhospital mortality (adjusted odds ratio, 1.18; 95% CI, 1.08–1.29; p < 0.001). CONCLUSIONS: In patients undergoing venoarterial extracorporeal membrane oxygenation, duration and severity of early hyperoxia were independently associated with poor neurologic outcomes at discharge and mortality.

OBJECTIVES: Stroke is commonly reported in patients receiving venovenous extracorporeal membrane oxygenation, but risk factors are not well described. We sought to determine preextracorporeal membrane oxygenation and on-extracorporeal membrane oxygenation risk factors for both ischemic and hemorrhagic strokes in patients with venovenous extracorporeal membrane oxygenation support. DESIGN: Retrospective analysis. SETTING: Data reported to the Extracorporeal Life Support Organization by 366 extracorporeal membrane oxygenation centers from 2013 to 2019. PATIENTS: Patients older than 18 years supported with a single run of venovenous extracorporeal membrane oxygenation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 15,872 venovenous extracorporeal membrane oxygenation patients, 812 (5.1%) had at least one type of acute brain injury, defined as ischemic stroke, hemorrhagic stroke, or brain death. Overall, 215 (1.4%) experienced ischemic stroke and 484 (3.1%) experienced hemorrhagic stroke. Overall inhospital mortality was 36%, but rates were higher in those with ischemic or hemorrhagic stroke (68% and 73%, respectively). In multivariable analysis, preextracorporeal membrane oxygenation pH (adjusted odds ratio = 0.10; 95% CI, 0.03–0.35; p < 0.001), hemolysis (adjusted odds ratio = 2.27; 95% CI, 1.22–4.24; p = 0.010), gastrointestinal hemorrhage (adjusted odds ratio = 2.01; 95% CI 1.12–3.59; p = 0.019), and disseminated intravascular coagulation (adjusted odds ratio = 3.61; 95% CI, 1.51–8.66; p = 0.004) were independently associated with ischemic stroke. Pre-extracorporeal membrane oxygenation pH (adjusted odds ratio = 0.28; 95% CI, 0.12–0.65; p = 0.003), preextracorporeal membrane oxygenation Po 2 (adjusted odds ratio = 0.96; 95% CI, 0.93–0.99; p = 0.021), gastrointestinal hemorrhage (adjusted odds ratio = 1.70; 95% CI, 1.15–2.51; p = 0.008), and renal replacement therapy (adjusted odds ratio=1.57; 95% CI, 1.22–2.02; p < 0.001) were independently associated with hemorrhagic stroke. CONCLUSIONS: Among venovenous extracorporeal membrane oxygenation patients in the Extracorporeal Life Support Organization registry, approximately 5% had acute brain injury. Mortality rates increased two-fold when ischemic or hemorrhagic strokes occurred. Risk factors such as lower pH and hypoxemia during the pericannulation period and markers of coagulation disturbances were associated with acute brain injury. Further research on understanding preextracorporeal membrane oxygenation and on-extracorporeal membrane oxygenation risk factors and the timing of acute brain injury is necessary to develop appropriate prevention and management strategies.