Intravenous oxygen microbubbles during cardiopulmonary resuscitation: a mechanistic simulation study.

BACKGROUND: Oxygen polymeric microbubbles (oPMB) deliver intravenous gaseous oxygen and improved survival in swine asphyxial cardiac arrest. Whether a candidate dose could support oxygenation in adult emergencies is unknown. METHODS: We built a computer simulation of oxygen transport in the body and applied it to two clinical scenarios: CPR-supported cardiac arrest (low blood flow, suppressed oxygen use, inadequate pulmonary oxygenation, e.g. ineffective bag-valve-mask ventilation) and a contrasting difficult-airway scenario (apnoeic, pre-oxygenated patient with spontaneous circulation). The intervention was 1 L of 50% oPMB foam over 10 minutes. The outcomes were cumulative time above an illustrative cerebral oxygen-delivery threshold (0.5 mL O2/100 g/min; a surrogate) in arrest, and time to arterial saturation below 80%, in the airway. RESULTS: In the arrest simulation, oPMB increased median cumulative time above the threshold from 4.7 to 11.8 minutes (median gain 6.9; 95% uncertainty interval [UI] 0.0 to 10.8; a ≥2-minute gain in 93% of simulations), compared to its control (CPR-generated low flow with inadequate pulmonary oxygenation, no oPMB). In the difficult-airway simulation, the median desaturation delay was 39 seconds (95% UI 1 to 105), compared to its control (without oPMB). Benefit was conditional on inadequate pulmonary oxygenation and redundant with effective ventilation. CONCLUSIONS: In this simulation model, oPMB only modestly extended the apnoeic window in the difficult-airway scenario. In contrast, during CPR-supported cardiac arrest with inadequate pulmonary oxygenation, oPMB may prolong cerebral oxygen delivery: a surrogate, not an improvement in survival or neurological outcome. Safety testing in an adult large-animal arrest model is warranted.