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 (SkMusSO(2)) 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 Ringer's solution. Results: The aortotomy rapidly de-creased the mean arterial pressure (MAP) to approximately 30 mm Hg and CO to 20% to 30% of baseline. The SkMusSO(2) 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 SkMusSO(2) group after T60. Mean infusion volumes were 180% and 100% of the bled volume collected at autopsy in the CO and SkMusSO(2) 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 SkMusSO(2) 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.