Combined effect of intermittent hemostasis and a modified external hemorrhage control device in a lethal swine model.

Background: Non-compressible torso hemorrhage (NCTH) presents the ultimate challenge in pre-hospital care. While external hemorrhage control devices (EHCDs) such as the Abdominal Aortic and Junctional Tourniquet (AAJT) and SAM Junctional Tourniquet (SJT) have been invented, the current design and application strategy requires further improvement. Therefore, researchers devised a novel apparatus named Modified EHCD (M-EHCD) and implemented intermittent hemostasis (IH) as a preventive measure against ischemia-reperfusion injury. The objective of this study was to ascertain the combined effect of M-EHCD and IH on the hemostatic effect of NCTH.

Methods: Eighteen swine were randomized to M-EHCD, AAJT or SJT. The NCTH model was established by inducing Class Ⅲ hemorrhagic shock and performing a hemi-transection of common femoral artery (CFA). EHCDs were rapidly fastened since the onset of free bleeding (T). The IH strategy was implemented by fully releasing M-EHCD at T, T and T, respectively, whereas AAJT and SJT maintained continuous hemostasis (CH) until T. All groups underwent CFA bridging at T, and EHCDs were removed at T. Reperfusion lasted for 60 min, after which euthanasia was performed. Hemodynamics, intra-vesical pressure (IVP), and blood samples were collected periodically. Histological examinations were also conducted.

Results: M-EHCD demonstrated the fastest application time (M-EHCD: 26.38 ± 6.32s vs. SJT: 30.84 ± 5.62s vs. AAJT: 54.28 ± 5.45s,  < 0.001) and reduced free blood loss (M-EHCD: 17.77 ± 9.85g vs. SJT: 51.80 ± 33.70g vs. AAJT: 115.20 ± 61.36g,  = 0.011) compared to SJT and AAJT. M-EHCD exhibited inhibitory effects on heart rate (M-EHCD: 91.83 ± 31.61bpm vs. AAJT: 129.00 ± 32.32bpm vs. SJT: 135.17 ± 21.24bpm,  = 0.041) and shock index. The device's external pressure was lowest in M-EHCD and highest in SJT ( = 0.001). The resultant increase in IVP were still the lowest in M-EHCD (M-EHCD: -0.07 ± 0.45 mmHg vs. AAJT: 27.04 ± 5.03 mmHg vs. SJT: 5.58 ± 2.55 mmHg,  < 0.001). Furthermore, M-EHCD caused the least colonic injury (M-EHCD: 1.17 ± 0.41 vs. AAJT: 2.17 ± 0.41 vs. SJT: 2.17 ± 0.41,  = 0.001). The removal of M-EHCD showed the slightest impact on pH ( < 0.001), while AAJT group was more susceptible to the lethal triad based on the arterial lactate and thrombelastogram results.

Conclusions: M-EHCD + IH protected the organs and reduced the risk of the lethal triad by decreasing disruptions to IVP, hemodynamics, acid-base equilibrium and coagulation. M-EHCD + IH was superior to the hemostatic safety and efficacy of AAJT/SJT + CH.