Mg++: Médicament de la coagulopathie ?

Both acute delivery of and storage with magnesium sulfate promote cold-stored platelet aggregation and coagulation function

Meledeo MA et Al. J Trauma Acute Care Surg. 2015 Oct;79(4 Suppl 2):S139-45

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Il y a quelque mois était publié un travail de recherche portant sur  l'intérêt de l'administration de Adénosine/Lidocaïne/Mg2+ ALM (1, 2, 3). Une hypothèse faite par les auteurs  serait que L'ALM agirait comme un antifibrinolytique en activant la voie du thrombin-activatable fibrinolysis inhibitor (TAFI) plutôt que celle de la protéine C. Cette action passerait par un mécanisme antiinflammatoire, une modification de la polarité endothéliale et une action sur la fonction plaquettaire. Le travail expérimental dont l'abstract est présenté met en avant l'intérêt de l'adminsitration de magnésium pour la restauration de la fonction plaquettaire après conservation de palquettes d'aphérèse au delà de 5 jours.

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BACKGROUND:

The platelet storage lesion causes loss of function and viability over time. A new paradigm for platelet storage is desired to enable safer, more effective transfusions while reducing waste. We hypothesized that repletion of Mg, which is chelated by citrate anticoagulant, could reduce platelet storage lesion severity when given in conjunction with storage at a refrigerated temperature.

METHODS:

Apheresis platelet units were collected from healthy donors and stored at 22°C or 4°C. On Days 0, 2, 4, and 8, samples were collected for analyses of receptor-mediated aggregation, coagulation, adhesion to collagen under flow, and viability. In the first series, samples were given anacute dose of MgSO4 before testing; in the second series, storage bags were supplemented with 0-, 3-, or 6-mM MgSO4.

RESULTS:

Acutely delivered MgSO4 induced a more rapid coagulation time in apheresis platelets, further enhanced by storage at 4°C. Plateletadhesion to a collagen surface while exposed to arterial shear rates (920 s) was enhanced by MgSO4 supplementation-acute MgSO4 had a large effect on adhesion of fresh platelets, which diminished more rapidly in 22°C samples, while storage with MgSO4 showed significant benefits even out to Day 4 at both temperatures. Although 4°C storage improves the longevity of platelet aggregation responses to agonists, MgSO4 supplementation did not change those responses.

CONCLUSION:

Acute MgSO4 reduces clot time likely through the transient increase of free Ca. Limited differences between platelet function inacute delivery of and storage with MgSO4 diminish the possibility that Mg-induced metabolic inhibition of platelets synergizes with 4°C storage. Regardless, magnesium supplementation to platelets is an exciting possibility in transfusion because the adhesion response of 22°C-stored platelets on Day 4 is significantly enhanced when stored with 6-mM MgSO4

IED à pied: Amputations 2aires fréquentes

Outcomes after Long-Term Follow-Up of Combat-Related Extremity Injuries in a Multidisciplinary Limb Salvage Clinic

Casey K et Al. Ann Vasc Surg. 2015 Apr;29(3):496-501

Background: Although the incidence of casualties from the Global War on Terror is decreasing, there remains a focus on the long-term sequelae from injuries sustained in the combat. Patients with prior significant limb injuries remain at risk of future complications. This study examines our institution’s experience with a multidisciplinary team approach toward this challenging patient population.

Methods: A retrospective review was performed on all patients treated in a single institution Limb Preservation Clinic over a 2-year period. Those patients who sustained a combatrelated injury in theater were examined. Patient demographics, mechanism of injury, amputation rates, time to amputation, and reasons for failure were examined.

Results: Ninety-four patients were evaluated in our multidisciplinary Limb Preservation Clinic over a 2-year period. Twenty patients (21%) were seen for combat-related injuries. Sixteen patients were evaluated and treated for chronic complications at a median of 13 months from their injury. All 16 patients were male with a median age of 24 years (range, 20e35). Ten patients sustained injuries secondary to a dismounted improvised explosive device (IED). All 16 patients had extensive soft tissue injuries and associated fractures. Only 2 patients sustained a vascular injury. The median number of prior surgeries to the affected limb was 8 (range, 3e19). The limb salvage rate of 37% was lower than our noncombat cohort (47%). The most common reasons for delayed amputation included chronic pain, osteomyelitis, and soft tissue infections.

Conclusions: The high secondary amputation rates seen in this cohort underscores the need for long-term follow-up. Despite successful initial outcomes, many patients eventually progress to limb loss. Patients who sustain a dismounted IED are at greatest risk for a delayed amputation. Identifying and addressing those factors which lead to delayed amputation should be a priority for returning war veterans and focus of future studies.