Characteristic Changes in Heart Rate Variability Indices during Hemorrhagic Shock, and Effect of Liposome‐Encapsulated Hemoglobin in Rats

Many compensatory mechanisms exit in hemorrhagic shock (HS). To characterize the efficacy of the new artificial oxygen carrier, liposome‐encapsulated hemoglobin (LHb), HS was induced by withdrawing 20% of the total blood volume from rats. Rats received one of five interventions: LHb resuscitation (LHb‐G, n = 7), normal saline (Saline‐G, n = 7), shed autologous blood (SAB‐G, n = 7), volume expander of 5% albumin (Albumin‐G, n = 7), or no treatment (Sham‐G, n = 7). Heart rate variability (HRV) indices were measured, including low frequency (LF, 0.10–0.60 Hz), high frequency (HF, 0.60–2.00 Hz), and the ratio of LF to HF (LF/HF). LF and LF/HF following HS were lower in the LHb‐G and SAB‐G groups when compared with the Saline‐G, Albumin‐G and Sham‐G groups. LF and LF/HF following HS in the LHb‐G group were comparable with that of the SAB‐G group. These data demonstrate that HS‐induced changes can be attenuated by resuscitation with LHb as well as SAB. LHb could be used as a substitute for blood transfusion for HS.