Surviving 60% blood loss using 7.5% NaCl with adenosine, lidocaine and magnesium (ALM) in the rat model of battlefield hemorrhagic shock

Soldiers with catastrophic blood loss often die on the battlefield before they can be evacuated. In an effort to translate the protective effects of AdenocaineTM (adenosine, lidocaine and Mg2+) (ALM) from cardiac surgery to resuscitation science, we examined the early hypotensive resuscitative effects of 7.5% NaCl with ALM following near lethal blood loss of 60% in the rat model. Methods: Male Sprague-Dawley rats (250–350g, n=32) were anesthetized and randomly assigned to one of four groups: 1) Untreated, 2) 7.5% NaCl, 3) 7.5% NaCl/6% Dextran-70 (RescueFlow®), 4) 7.5% NaCl/ALM. Shock was induced by removing 60% blood (volume controlled) over 50 min and maintaining the MAP between 30 to 40 mmHg. Animals were left in shock at 34°C for an additional 30 min. Total shock time was 80 min. 0.3 ml bolus was injected into the femoral vein and hemodynamics monitored for 60 min (Phase 1). Shed blood was replaced and function monitored for another 60 min (Phase 2). Lead II ECG, arterial pressures, MAP, heart rate (HR) and rate-pressure product (RPP) were monitored. Results: Mortality (%) for Untreated, 7.5% NaCl, 7.5% NaCl/6% Dextran-70, and 7.5% NaCl ALM groups were 100%, 75%, 87.5% and 0% respectively. Times to death after bolus injection were 9±3, 19±4 and 45±12 min respectively. The MAP of survivors at the end of Phase 1 was 24±3 (n=2), 26±0.1 (n=3) and 40±2 mmHg (P<0.05) (n=8) respectively. After blood was returned, the MAP at 60 min for the three treatment groups was 67±5 (n=2), 47 (n=1) and 69±5 mmHg (n=8) respectively. All rats, except the 7.5% NaCl ALM group, were profoundly proarrhythmic; Dextran doubled the arrhythmias compared with 7.5% NaCl alone. No severe arrhythmias occurred in ALM group in Phase 1 or 2, and 60 min after return of shed blood HR, MAP and RPP were 96%, 75% and 83% of their pre-shock values. Conclusions: Ultra-small (