Evaluation of Miniature Dynamic Light Scattering Technology for the Assessment of Hemodynamic Status During Graded Hemorrhage and Retransfusion in Pigs.

BACKGROUND: Hemorrhagic shock with occult hypoperfusion is a key challenge to prehospital staff during triage and transfer of patients, especially during mass casualty incidents. Recent advances in Dynamic Light Scattering (DLS), and miniaturization of this technology, has resulted in noninvasive sensors capable of continuously monitoring tissue perfusion. This study evaluated the ability of miniature DLS (mDLS) sensors to assess hemodynamic status in a porcine model of hemorrhage.

METHODS: Following ethics committee approval, anesthetized and ventilated pigs underwent graded hemorrhage and then retransfusion. Standard vital signs were monitored in conjunction with a thermodilution cardiac output (CO), central venous pressure (CVP), and arterial blood gases. The mDLS sensor was attached to each animal's leg and all monitoring measurements were taken 5 minutes after completion of each period of hemorrhage and retransfusion to allow equilibration.

RESULTS: All measured parameters changed during bleeding and retransfusion. During bleeding; p value were 0.011 for heart rate, 0.07 for CVP, <0.001 for both mean arterial pressure, and mDLS. During retransfusion; p values were 0.023 for heart rate, 0.008 for CVP, and <0.001 for both mean arterial pressure and mDLS. Pearson correlation between changes in mDLS and CO demonstrated r value of 0.917 during hemorrhage and 0.965 during retransfusion. Changes in hemoglobin were not statistically significant during bleeding (p = 0.331) but were during retransfusion (p = 0.0001). Changes of bicarbonate, base excess, and lactate were found to be statistically significant during both phases of the experiment (p = 0.001).

CONCLUSIONS: In an animal model of hemorrhagic shock, the mDLS sensor strongly correlates with traditional measures of CO. This initial assessment supports further investigation of this technology in human studies.