Background Mechanical chest compression (CC) is currently suggested to deliver sustained high‐quality CC in a moving ambulance. This study compared the hemodynamic support provided by a mechanical piston device or manual CC during ambulance transport in a porcine model of cardiopulmonary resuscitation. Methods and Results In a simulated urban ambulance transport, 16 pigs in cardiac arrest were randomized to 18 minutes of mechanical CC with the LUCAS (n=8) or manual CC (n=8). ECG, arterial and right atrial pressure, together with end‐tidal CO 2 and transthoracic impedance curve were continuously recorded. Arterial lactate was assessed during cardiopulmonary resuscitation and after resuscitation. During the initial 3 minutes of cardiopulmonary resuscitation, the ambulance was stationary, while then proceeded along a predefined itinerary. When the ambulance was stationary, CC‐generated hemodynamics were equivalent in the 2 groups. However, during ambulance transport, arterial and coronary perfusion pressure, and end‐tidal CO 2 were significantly higher with mechanical CC compared with manual CC (coronary perfusion pressure: 43±4 versus 18±4 mmHg; end‐tidal CO 2 : 31±2 versus 19±2 mmHg, P <0.01 at 18 minutes). During cardiopulmonary resuscitation, arterial lactate was lower with mechanical CC compared with manual CC (6.6±0.4 versus 8.2±0.5 mmol/L, P <0.01). During transport, mechanical CC showed greater constancy compared with the manual CC, as represented by a higher CC fraction and a lower transthoracic impedance curve variability ( P <0.01). All animals in the mechanical CC group and 6 (75%) in the manual one were successfully resuscitated. Conclusions This model adds evidence in favor of the use of mechanical devices to provide ongoing high‐quality CC and tissue perfusion during ambulance transport.
Background Ventilation with the noble gas argon (Ar) has shown neuroprotective and cardioprotective properties in different in vitro and in vivo models. Hence, the neuroprotective effects of Ar were investigated in a severe, preclinically relevant porcine model of cardiac arrest. Methods and Results Cardiac arrest was ischemically induced in 36 pigs and left untreated for 12 minutes before starting cardiopulmonary resuscitation. Animals were randomized to 4‐hour post‐resuscitation ventilation with: 70% nitrogen–30% oxygen (control); 50% Ar–20% nitrogen–30% oxygen (Ar 50%); and 70% Ar–30% oxygen (Ar 70%). Hemodynamic parameters and myocardial function were monitored and serial blood samples taken. Pigs were observed up to 96 hours for survival and neurological recovery. Heart and brain were harvested for histopathology. Ten animals in each group were successfully resuscitated. Ninety‐six‐hour survival was 60%, 70%, and 90%, for the control, Ar 50%, and Ar 70% groups, respectively. In the Ar 50% and Ar 70% groups, 60% and 80%, respectively, achieved good neurological recovery, in contrast to only 30% in the control group ( P <0.0001). Histology showed less neuronal degeneration in the cortex ( P <0.05) but not in the hippocampus, and less reactive microglia activation in the hippocampus ( P =0.007), after Ar compared with control treatment. A lower increase in circulating biomarkers of brain injury, together with less kynurenine pathway activation ( P <0.05), were present in Ar‐treated animals compared with controls. Ar 70% pigs also had complete left ventricular function recovery and smaller infarct and cardiac troponin release ( P <0.01). Conclusions Post‐resuscitation ventilation with Ar significantly improves neurologic recovery and ameliorates brain injury after cardiac arrest with long no‐flow duration. Benefits are greater after Ar 70% than Ar 50%.
A.M. conceived the study, performed animal experiments, collected, interpreted and analyzed experimental and clinical data, data, analyzed chest CT scan images, searched literature, and wrote the manuscript; E.R. collected clinical data, interpreted and analyzed experimental and clinical data, searched literature, and wrote the manuscript; D.Z. and M.M. performed CT scans in the animal model and analyzed chest CT scan images; D.D.G and D.O. performed animal experiments; F.F. interpreted data and revised the manuscript; T.L. provided clinical data and revised the manuscript; L.A. provided clinical data and revised the manuscript; G.G. provided clinical data and revised the manuscript; R.L. and A.P. interpreted data and revised the manuscript; G.B. supervised the study project, provided clinical data and is the coordinator of the multicenter clinical study, interpreted experimental and clinical data and wrote the manuscript; G.R. conceived the study, performed animal experiments, collected and interpreted animal data, and revised the manuscript.All authors gave final approval of the version to be published and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy and integrity of any part of the work are appropriately investigated and resolved.
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