Introduction: In-hospital cardiac arrest is precipitated by severe hypoxemia in 45% of cases, a subset of patients who suffer severe neurologic injury. Favorable outcomes requires the immediate reversal of hypoxia to the brain and myocardium. The IV injection of oxygen gas may be possible by packaging the gas into injectable, biocompatible microparticles. Here, we investigate the impact of IV oxygen on survival in asphyxial cardiac arrest.
Methods: We manufactured oxygen microparticles whose shell was made of composite nanoparticles made from amphiphilic modified dextran polymers (Ox-MBs). Male Sprague Dawley rats were anesthetized, intubated, ventilated (FiO2 0.3), paralyzed, and instrumented, then underwent complete asphyxia by tracheal occlusion until cardiac arrest (pulse pressure < 5mmHg). Animals remained asphyxiated for 10 minutes thereafter, and were treated according to ACLS resuscitation guidelines with or without Ox-MBs (4 mL of either Ox-MBs or carrier fluid every 2 min). Thereafter, ventilation was restored and ACLS continued for 10 additional minutes or ROSC, whichever came first. Surviving animals were observed for an additional hour.
Results: Ox-MBs have a mean diameter of 3.6±1.6 μm and an ultra-thin shell, and contain 40 mL oxygen per dL emulsion. In asphyxial cardiac arrest, the addition of Ox-MBs to the treatment resulted in higher arterial oxygen tension (P < 0.001), higher systolic blood pressure during CPR P < 0.01), and a higher incidence of ROSC (P=0.02).
Conclusions: Intravenous Ox-MBs reverse severe hypoxemia during cardiac arrest and improve ROSC, and may be a useful adjunctive therapy in asphyxial cardiac arrest.