A small amount can make a difference: a prospective human study of the paradoxical coagulation characteristics of hemothorax

Cell Salvage in Oncological Surgery, Peripartum Haemorrhage and Trauma

Oncological surgery, obstetric haemorrhage and severe trauma are the most challenging conditions for establishing clinical recommendations for the use of cell salvage. When the likelihood of allogeneic transfusion is high, the intraoperative use of this blood-saving technique would be justified, but specific patient selection criteria are needed. The main concerns in the case of oncological surgery are the reinfusion of tumour cells, thereby increasing the risk of metastasis. This threat could be minimized, which may help to rationalize its indication. In severe peripartum haemorrhage, cell salvage has not proven cost-effective, damage control techniques have been developed, and, given the risk of fetomaternal alloimmunization and amniotic fluid embolism, it is increasingly out of use. In trauma, bleeding may originate from multiple sites, coagulopathy may develop, and it should be evaluated whether re-transfusion of autologous blood collected from uncontaminated organ cavities would be feasible. General safety measures include washing recovered blood and its passage through leukocyte depletion filters. To date, no well-defined indications for cell salvage have been established for these pathologies, but with accurate case selection and selective implementation, it could become safe and effective. Randomized clinical trials are urgently needed.

Evaluation of hemostatic capacities among commando candidates: Would their blood suit a hemorrhagic war-injured patient in case of blood donation on the battlefield?

BACKGROUND

In case of a warm fresh whole blood transfusion on the battlefield, the blood donation usually occurs just after a combat phase and often after several days on the fields. To explore the hemostatic capacity of such blood, we analyzed the blood of volunteers attending the commando course of the French Navy, considering this course as an experimental model, placing them into the same physiological conditions as those faced by deployed fighters.

METHODS

Venous blood was collected at the beginning of the course, mimicking their baseline status, and a second time 6 weeks later, from the remaining candidates, during the actual commando training, mimicking the stress conditions. For each candidate, we observed the differences between the two blood samples.

RESULTS

Of the 112 men that attended the first day of the course, only 17 remained 6 weeks later. In the second blood samples, we noted significant increased leucocytes and platelets counts and significant decreased hematocrit and hemoglobin levels. Thrombin generation assays showed significantly lower normalized peak heights (-31%), lower normalized endogenous thrombin potential values (-29%), and lower velocity index (-35%). Normalized lag time and time to peak did not differ. Viscoelastometric testing revealed a significant increasing in clot firmness as assessed by maximum amplitude and amplitude at 6 minutes. The clot speed was significantly increased.

CONCLUSION

This work brings new data on coagulation during prolonged and considerable physical exercise. No obvious deleterious modification of hemostatic properties was observed. The decrease of the endogenous thrombin potentials may reflect a better ability to control the thrombin generation once started. Altogether, these results suggest that this blood could suit well a hemorrhagic war-injured patient.

LEVEL OF EVIDENCE

Prospective observational cohort study, Level III.

Cell salvage in trauma

PURPOSE OF REVIEW

The collection of shed blood and its reinfusion has been termed 'cell salvage' or 'autotransfusion'. This review will summarize the historical foundation of cell salvage and summarize recent literature associated with cell salvage use in trauma.

RECENT FINDINGS

There have been no publications on cell salvage in trauma during the last 2 years. This is based on a PubMed search using the key words, 'cell salvage', 'autologous blood transfusion' and 'operative blood salvage'. Although the wars in Iraq and Afghanistan were ongoing, publications focused upon autotranfusion of unwashed blood from the hemothorax and on the resuscitation of the injured in remote settings.

SUMMARY

Autotransfusion or cell salvage is markedly under utilized in trauma. Opportunities exist for significant blood savings if it is used more frequently. More research is clearly needed to assess the safety of autotransfusion in the traumatized patient.

Traumatic Hemothorax Blood Contains Elevated Levels of Microparticles that are Prothrombotic but Inhibit Platelet Aggregation

OBJECTIVES

Autotransfusion of shed blood from traumatic hemothorax is an attractive option for resuscitation of trauma patients in austere environments. However, previous analyses revealed that shed hemothorax (HX) blood is defibrinated, thrombocytopenic, and contains elevated levels of D-dimer. Mixing studies with normal pooled plasma demonstrated hypercoagulability, evoking concern for potentiation of acute traumatic coagulopathy. We hypothesized that induction of coagulopathic changes by shed HX blood may be due to increases in cellular microparticles (MP) and that these may also affect recipient platelet function.

METHODS

Shed HX blood was obtained from 17 adult trauma patients under an Institutional Review Board approved prospective observational protocol. Blood samples were collected every hour up to 4 h after thoracostomy tube placement. The corresponding plasma was isolated and frozen for analysis. The effects of shed HX frozen plasma (HFP) and isolated HX microparticles (HMP) on coagulation and platelet function were assessed through mixing studies with platelet-rich plasma at various dilutions followed by analysis with thromboelastometry (ROTEM), platelet aggregometry (Multiplate), enzyme-linked immunosorbent assays, and flow cytometry. Furthermore, HFP was assessed for von Willebrand factor antigen levels and multimer content, and plasma-free hemoglobin.

RESULTS

ROTEM analysis demonstrated that diluted HFP and isolated HMP samples decreased clotting time, clotting formation time, and increased α angle, irrespective of sample concentrations, when compared with diluted control plasma. Isolated HMP inhibited platelet aggregation in response to adenosine diphosphate, arachidonic acid, and collagen. HFP contained elevated levels of fibrin-degradation products and tissue factor compared with control fresh frozen plasma samples. MP concentrations in HFP were significantly increased and enriched in events positive for phosphatidylserine, tissue factor, CD235, CD45, CD41a, and CD14. von Willebrand factor (vWF) multimer analysis revealed significant loss of high molecular weight multimers in HFP samples. Plasma-free hemoglobin levels were 8-fold higher in HFP compared with fresh frozen plasma.

CONCLUSION

HFP induces plasma hypercoagulability that is likely related to increased tissue factor and phosphatidylserine expression originating from cell-derived MP. In contrast, platelet dysfunction is induced by HMP, potentially aggravated by depletion of high molecular weight multimers of vWF. Thus, autologous transfusion of shed traumatic hemothorax blood may induce a range of undesirable effects in patients with acute traumatic coagulopathy.

Management of blunt pulmonary injury

Thoracic injuries account for 25% of all civilian deaths. Blunt force injuries are a subset of thoracic injuries and include injuries of the tracheobronchial tree, pleural space, and lung parenchyma. Early identification of these injuries during initial assessment and resuscitation is essential to reduce associated morbidity and mortality rates. Management of airway injuries includes definitive airway control with identification and repair of tracheobronchial injuries. Management of pneumothorax and hemothorax includes pleural space drainage and control of ongoing hemorrhage, along with monitoring for complications such as empyema and chylothorax. Injuries of the lung parenchyma, such as pulmonary contusion, may require support of oxygenation and ventilation through both conventional and nonconventional mechanical ventilation strategies. General strategies to improve pulmonary function and gas exchange include balanced fluid resuscitation to targeted volume-based resuscitation end points, positioning therapy, and pain management.

Early autologous fresh whole blood transfusion leads to less allogeneic transfusions and is safe

BACKGROUND

The practice of transfusing ones' own shed whole blood has obvious benefits such as reducing the need for allogeneic transfusions and decreasing the need for other fluids that are typically used for resuscitation in trauma. It is not widely adopted in the trauma setting because of the concern of worsening coagulopathy and the inflammatory process. The aim of this study was to assess outcomes in trauma patients receiving whole blood autotransfusion (AT) from hemothorax.

METHODS

This is a multi-institutional retrospective study of all trauma patients who received autologous whole blood transfusion from hemothorax from two Level I trauma centers. Patients who received AT were matched to patients who did not receive AT (No-AT) using propensity score matching in a 1:1 ratio for admission age, sex, mechanism, type of injury, Injury Severity Score (ISS), Glasgow Coma Scale (GCS) score, systolic blood pressure, heart rate, hemoglobin, international normalized ratio (INR), prothrombin time, partial prothrombin time, and lactate. AT was defined as transfusion of autologous blood from patient's hemothorax, which was collected from the chest tubes and anticoagulated with citrate phosphorous dextrose. Outcome measures were in-hospital complications, 24-hour INR, and mortality. In-hospital complications were defined as adult respiratory distress syndrome, sepsis, disseminated intravascular coagulation, renal insufficiency, and transfusion-related acute lung injury.

RESULTS

A total of 272 patients (AT, 136; No-AT, 136) were included. There was no difference in admission age (p = 0.6), ISS (p = 0.56), head Abbreviated Injury Scale (AIS) score (p = 0.42), systolic blood pressure (p = 0.88), and INR (p = 0.62) between the two groups. There was no significant difference in in-hospital complications (p = 0.61), mortality (p = 0.51), and 24-hour postadmission INR (0.31) between the AT and No-AT groups. Patients who received AT had significantly lower packed red blood cell (p = 0.01) and platelet requirements (p = 0.01). Cost of transfusions (p = 0.01) was significantly lower in the AT group compared with the No-AT group.

CONCLUSION

The autologous transfusion of the patient's shed blood collected through chest tubes for hemothorax was found to be safe without complications in this study. It also reduced the need for allogeneic transfusions and decreased hospital costs. This study demonstrates safety data that would help in designing larger prospective multicenter studies to determine whether this practice is truly safe and effective.

LEVEL OF EVIDENCE

Epidemiologic/prognostic study, level III.

Management of Blunt Pulmonary Injury

Thoracic injuries account for 25% of all civilian deaths. Blunt force injuries are a subset of thoracic injuries and include injuries of the tracheobronchial tree, pleural space, and lung parenchyma. Early identification of these injuries during initial assessment and resuscitation is essential to reduce associated morbidity and mortality rates. Management of airway injuries includes definitive airway control with identification and repair of tracheobronchial injuries. Management of pneumothorax and hemothorax includes pleural space drainage and control of ongoing hemorrhage, along with monitoring for complications such as empyema and chylothorax. Injuries of the lung parenchyma, such as pulmonary contusion, may require support of oxygenation and ventilation through both conventional and nonconventional mechanical ventilation strategies. General strategies to improve pulmonary function and gas exchange include balanced fluid resuscitation to targeted volume-based resuscitation end points, positioning therapy, and pain management.