Background: We describe implementation, evaluate performance, and report outcomes from the first program serving an entire metropolitan area designed to rapidly deliver extracorporeal membrane oxygenation (ECMO)-facilitated resuscitation to patients with refractory ventricular fibrillation/ventricular tachycardia (VF/VT) out-of-hospital cardiac arrest (OHCA). Methods: This observational cohort study analyzed consecutive patients prospectively enrolled in the Minnesota Mobile Resuscitation Consortium's ECMO-facilitated resuscitation program. Entry criteria included: 1) adults (aged 18À75), 2) VF/VT OHCA, 3) no return of spontaneous circulation following 3 shocks, 4) automated cardiopulmonary resuscitation with a Lund University Cardiac Arrest System (LUCAS TM ), and 5) estimated transfer time of < 30 min. The primary endpoint was functionally favorable survival to hospital discharge with Cerebral Performance Category (CPC) 1 or 2. Secondary endpoints included 3-month functionally favorable survival, program benchmarks, ECMO cannulation rate, and safety. Essential program components included emergency medical services, 3 community ECMO Initiation Hospitals with emergency department ECMO cannulation sites and 24/7 cardiac catheterization laboratories, a 24/7 mobile ECMO cannulation team, and a single, centralized ECMO intensive care unit. Findings: From December 1, 2019 to April 1, 2020, 63 consecutive patients were transported and 58 (97%) met criteria and were treated by the mobile ECMO service. Mean age was 57 § 1.8 years; 46/58 (79%) were male. Program benchmarks were variably met, 100% of patients were successfully cannulated, and no safety issues were identified. Of the 58 patients, 25/58 (43% [CI:31À56%]) were both discharged from the hospital and alive at 3 months with CPC 1 or 2.

Secondary R-and β-deuterium isotope effects for enolization reactions and equilibria have been determined by ab initio calculations, 1 H NMR spectroscopy, and triton exchange kinetics. Kinetic and equilibrium R-deuterium isotope effects for hydroxide ion-catalyzed enolization of acetaldehyde calculated by ab initio methods are normal and depend on the orientation of the secondary hydrogen with respect to the carbonyl group. The computed transition state structure indicates a small degree of bond rehybridization at the transition state. Experimentally measured secondary isotope effects on the deuteroxide ion-catalyzed proton exchange of acetophenone are k H /k D ) 1.08 ( 0.07 for R-CH 3 exchange and k H /k D ) 0.96 ( 0.08 for R-CH 2 D exchange. For R-CH 2 T exchange in water, the corresponding secondary isotope effect is k H /k D ) 1.06 ( 0.02, assuming the rule of the geometric mean is valid. These effects are smaller than the calculated equilibrium isotope effect for formation of the enolate ion-water complex: K H /K D ) 1.11-1.22 at the MP2 level. The normal kinetic isotope effects are smaller than might be expected due to a loss in hyperconjugation of the out-of-plane C-H bond and a lag in structural reorganization that contributes to the intrinsic barrier for proton transfer from carbon. Ionization of protonated acetone gives rise to an inverse secondary isotope effect of 0.97/D for the C-L bond adjacent to the carbonyl group and is consistent with a loss in hyperconjugation upon formation of the neutral ketone.

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