Near-infrared spectroscopy-guided closed-loop resuscitation of hemorrhage

Background: Endpoint resuscitation has been suggested as a better means to resuscitate penetrating injury. We performed computer-controlled closed-loop resuscitation using invasive cardiac output (CO) or noninvasive skeletal muscle oxygen saturation (SkMusSO₂) via near infrared spectroscopy (NIRS). Methods: Conscious sheep received a 4.0-mm aortotomy and uncontrolled hemorrhage at t = 0 min (TO) while resuscitation started at T20 using lactated Ring. er's solution. Results: The aortotomy rapidly decreased the mean arterial pressure (MAP) to approximately 30 mm Hg and CO to 20% to 30% of baseline. The SkMusSO₂ endpoint group required only half as much fluid through 4 hours of resuscitation as the CO endpoint group (34.9 ± 8.4 mL/kg vs. 63.1 ± 9.4 mL/kg). CO and MAP were lower in the SkMusSO₂ group after T60. Mean infusion volumes were 180% and 100% of the bled volume collected at autopsy in the CO and SkMusSO₂ groups. Brain and muscle oxygenation and base excess were as high or higher in the CO endpoint group. Conclusion: Closed-loop resuscitation with either CO or SkMusSO₂ endpoints effectively performs fluid resuscitation of severe uncontrolled hemorrhagic shock. Limited resuscitation may achieve favorable clinical results with volumes less than recommended by Advanced Trauma Life Support guidelines.