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.