Plasma resuscitation improves and restores intestinal microcirculatory physiology following haemorrhagic shock

PLASMA UTILIZATION EXACERBATES RENAL CORTEX INFLAMMATION IN A RODENT MODEL OF HEMORRHAGIC SHOCK AND RESUSCITATION

ABSTRACT

Background and Hypothesis: Resuscitation strategies incorporating fresh frozen plasma have become the standard of care in the management of traumatic hemorrhagic shock. While plasma resuscitation has been shown to augment the circulation and reduce inflammation within the splanchnic and pulmonary circulation, its global effect on the kidney remains unknown. We hypothesized that plasma would improve intrarenal blood flow and reduce parenchymal inflammation when compared to resuscitation with lactated ringer's. Methods: Animals were randomized into four groups (n = 8): a) baseline, b) hemorrhagic shock alone, c) lactated ringer's resuscitation, and d) fresh frozen plasma resuscitation. Multiplex immunoassays were used to evaluate cytokine and chemokine signaling within the renal cortex and immunohistochemistry was used to identify leukocyte infiltration. Doppler ultrasonography was used to evaluate changes in blood flow and maximum kidney diameter during hemorrhagic shock and resuscitation. Results: While no difference in resistive index (surrogate for blood flow) within the renal artery or parenchymal vessels was observed between resuscitation strategies, plasma resulted in increased transverse kidney diameter. Plasma administration promoted cytokine/chemokine signaling, resulting in increased infiltration of leukocytes within the renal cortex when compared to lactated ringer's. Conclusion: Although the clinical benefits of plasma resuscitation mandate its utilization, our current findings highlight the complexities of plasma resuscitation. While the increase in renal diameter may be related to augmentation of the microcirculation, plasma resuscitation did not enhance macro-circulatory blood flow. Furthermore, plasma resuscitation appears to exacerbate inflammation within the renal cortex after hemorrhage. The downstream physiologic implications of plasma-induced inflammation warrant further exploration.

Intestinal oxygen utilisation and cellular adaptation during intestinal ischaemia-reperfusion injury

The gastrointestinal tract can be deranged by ailments including sepsis, trauma and haemorrhage. Ischaemic injury provokes a common constellation of microscopic and macroscopic changes that, together with the paradoxical exacerbation of cellular dysfunction and death following restoration of blood flow, are collectively known as ischaemia-reperfusion injury (IRI). Although much of the gastrointestinal tract is normally hypoxemic, intestinal IRI results when there is inadequate oxygen availability due to poor supply (pathological hypoxia) or abnormal tissue oxygen use and metabolism (dysoxia). Intestinal oxygen uptake usually remains constant over a wide range of blood flows and pressures, with cellular function being substantively compromised when ischaemia leads to a >50% decline in intestinal oxygen consumption. Restoration of perfusion and oxygenation provokes additional injury, resulting in mucosal damage and disruption of intestinal barrier function. The primary cellular mechanism for sensing hypoxia and for activating a cascade of cellular responses to mitigate the injury is a family of heterodimer proteins called hypoxia-inducible factors (HIFs). The HIF system is connected to numerous biochemical and immunologic pathways induced by IRI and the concentration of those proteins increases during hypoxia and dysoxia. Activation of the HIF system leads to augmented transcription of specific genes in various types of affected cells, but may also augment apoptotic and inflammatory processes, thus aggravating gut injury. KEY POINTS: During intestinal ischaemia, mitochondrial oxygen uptake is reduced when cellular oxygen partial pressure decreases to below the threshold required to maintain normal oxidative metabolism. Upon reperfusion, intestinal hypoxia may persist because microcirculatory flow remains impaired and/or because available oxygen is consumed by enzymes, intestinal cells and neutrophils.

Massive transfusion in trauma

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of currently recommended treatment approaches for traumatic hemorrhage shock, with a special focus on massive transfusion.

RECENT FINDINGS

Severe trauma patients require massive transfusion, but consensual international definitions for traumatic hemorrhage shock and massive transfusion are missing. Current literature defines a massive transfusion as transfusion of a minimum of 3-4 packed red blood cells within 1 h. Using standard laboratory and/or viscoelastic tests, earliest diagnosis and treatment should focus on trauma-induced coagulopathy and substitution of substantiated deficiencies.

SUMMARY

To initiate therapy immediately massive transfusion protocols are helpful focusing on early hemorrhage control using hemostatic dressing and tourniquets, correction of metabolic derangements to decrease coagulopathy and substitution according to viscoelastic assays and blood gases analysis with tranexamic acid, fibrinogen concentrate, red blood cells, plasma and platelets are recommended. Alternatively, the use of whole blood is possible. If needed, further support using prothrombin complex, factor XIII or desmopressin is suggested.

Lilrb4 ameliorates ileal injury in rats with hemorrhagic shock and suppresses the activation of NF-κB signaling pathway

Hemorrhagic shock (HS) leads to intestinal damage and subsequent multiple organ dysfunction syndrome. Intestinal barrier dysfunction is the main cause of multiple organ failure associated with HS. Leukocyte immunoglobulin-like receptor B4 (Lilrb4) belongs to the Ig superfamily and is a vital natural immunomodulatory receptor. The purpose of this study was to identify the role and molecular mechanism of Lilrb4 in HS-induced ileal injury. In this work, HS was established by femoral artery cannula and 90 min of HS (blood pressure, 35-40 mmHg), followed by resuscitation. RNA sequencing analysis showed that Lilrb4 was highly expressed in the ileum of HS rats. As observed, HS rats exhibited severe ileal injury, characterized by enlarged subepithelial space, edema, exfoliation and extensive loss of villi. Whereas, lentivirus system-mediated Lilrb4 overexpression considerably mitigated these alterations. HS led to increased release of markers associated with intestinal injury, which was effectively reversed by Lilrb4 overexpression. In addition, after resuscitation, Lilrb4 overexpression inhibited HS-triggered inflammatory response, as evidenced by decreased levels of proinflammatory cytokines. Lilrb4 also inhibited the activation of NF-κB signal induced by HS. Notably, Lilrb4 modulated the balance of regulatory T (Treg)-T helper 17 (Th17) cells in the mesenteric lymph node (MLN), which may also contribute to its protective role in HS progression. In aggregate, these findings confirmed that Lilrb4 overexpression protected against ileal injury caused by HS, indicating that Lilrb4 may be a potential candidate for the treatment of HS.

Local carbachol application induces oral microvascular recruitment and improves gastric tissue oxygenation during hemorrhagic shock in dogs

Introduction

Hemorrhagic shock is characterized by derangements of the gastrointestinal microcirculation. Topical therapy with nitroglycerine or iloprost improves gastric tissue oxygenation but not regional perfusion, probably due to precapillary adrenergic innervation. Therefore, this study was designed to investigate the local effect of the parasympathomimetic carbachol alone and in combination with either nitroglycerine or iloprost on gastric and oral microcirculation during hemorrhagic shock.

Methods

In a cross-over design five female foxhounds were repeatedly randomized into six experimental groups. Carbachol, or carbachol in combination with either nitroglycerine or iloprost were applied topically to the oral and gastric mucosa. Saline, nitroglycerine, or iloprost application alone served as control groups. Then, a fixed-volume hemorrhage was induced by arterial blood withdrawal followed by blood retransfusion after 1h of shock. Gastric and oral microcirculation was determined using reflectance spectrophotometry and laser Doppler flowmetry. Oral microcirculation was visualized with videomicroscopy. Statistics: 2-way-ANOVA for repeated measurements and Bonferroni post-hoc analysis (mean ± SEM; p < 0.05).

Results

The induction of hemorrhage led to a decrease of gastric and oral tissue oxygenation, that was ameliorated by local carbachol and nitroglycerine application at the gastric mucosa. The sole use of local iloprost did not improve gastric tissue oxygenation but could be supplemented by local carbachol treatment. Adding carbachol to nitroglycerine did not further increase gastric tissue oxygenation. Gastric microvascular blood flow remained unchanged in all experimental groups. Oral microvascular blood flow, microvascular flow index and total vessel density decreased during shock. Local carbachol supply improved oral vessel density during shock and oral microvascular flow index in the late course of hemorrhage.

Conclusion

The specific effect of shifting the autonomous balance by local carbachol treatment on microcirculatory variables varies between parts of the gastrointestinal tract. Contrary to our expectations, the improvement of gastric tissue oxygenation by local carbachol or nitroglycerine application was not related to increased microvascular perfusion. When carbachol is used in combination with local vasodilators, the additional effect on gastric tissue oxygenation depends on the specific drug combination. Therefore, modulation of tissue oxygen consumption, mitochondrial function or alterations in regional blood flow distribution should be investigated.