Complexity analysis of arterial pressure during periods of abrupt hemodynamic changes.

In this communication, we estimated the Lempel-Ziv complexity (LZC) on over 40 h of arterial blood pressure (ABP) recordings corresponding to 18 mechanically ventilated animal subjects. In this study, all subjects underwent a period of abrupt hemodynamic changes after an induced injury involving severe blood loss leading to hemorrhagic shock, followed by fluid resuscitation using either lactated ringers or 0.9% normal saline. The LZC metric experienced a statistically significant increase (p < 0.01) immediately following the induced injury and a statistically significant reduction following the administration of fluid therapy (p < 0.01). These results indicate that LZC of ABP may be useful as a dynamic metric to assess fluid responsiveness.