Monitoring the response to injury

Fat embolism syndrome with neurological involvement: A case report

Background

Fat Embolism Syndrome (FES) occurs when the contents (or some component of) the bone marrow is released into the circulation, generally as the result of long bone fracture. It poses significant challenges in both diagnosis and treatment and, as such, is primarily a diagnosis of exclusion with no definitive treatment. We present a case where heightened awareness of the clinical team allowed for early identification and immediate initiation of supportive care, nitric oxide (NO) for potential mitigation of right heart failure, and pharmacological treatment with atorvastatin.

Patient

A 16-year-old male with multi-system trauma, including bilateral long-bone fractures, developed Fat Embolism Syndrome with neurological and respiratory symptoms within 24 h of admission.

Results

Within 24 h of initiation of high dose atorvastatin and inhaled Nitric Oxide our patient showed signs of improvement, including decreasing oxygen requirement's and normalization of mental status.

Conclusion

We postulate that the combined therapy of high-dose atorvastatin with Nitric Oxide may have played a role in our patients' full recovery in a shortened timeframe. Ideally, further prospective research is needed to determine a universally accepted treatment regimen for pediatric patients with FES.

Increased complement activation 3 to 6 h after trauma is a predictor of prolonged mechanical ventilation and multiple organ dysfunction syndrome: a prospective observational study

Background

Complement activation is a central mechanism in systemic inflammation and remote organ dysfunction following major trauma. Data on temporal changes of complement activation early after injury is largely missing. We aimed to describe in detail the kinetics of complement activation in individual trauma patients from admission to 10 days after injury, and the association with trauma characteristics and outcome.

Methods

In a prospective cohort of 136 trauma patients, plasma samples obtained with high time resolution (admission, 2, 4, 6, 8 h, and thereafter daily) were assessed for terminal complement complex (TCC). We studied individual TCC concentration curves and calculated a summary measure to obtain the accumulated TCC response 3 to 6 h after injury (TCC-AUC_3–6). Correlation analyses and multivariable linear regression analyses were used to explore associations between individual patients’ admission TCC, TCC-AUC_3–6, daily TCC during the intensive care unit stay, trauma characteristics, and predefined outcome measures.

Results

TCC concentration curves showed great variability in temporal shapes between individuals. However, the highest values were generally seen within the first 6 h after injury, before they subsided and remained elevated throughout the intensive care unit stay. Both admission TCC and TCC-AUC_3–6 correlated positively with New Injury Severity Score (Spearman’s rho, p-value 0.31, 0.0003 and 0.21, 0.02) and negatively with admission Base Excess (− 0.21, 0.02 and − 0.30, 0.001). Multivariable analyses confirmed that deranged physiology was an important predictor of complement activation. For patients without major head injury, admission TCC and TCC-AUC_3–6 were negatively associated with ventilator-free days. TCC-AUC_3–6 outperformed admission TCC as a predictor of Sequential Organ Failure Assessment score at day 0 and 4.

Conclusions

Complement activation 3 to 6 h after injury was a better predictor of prolonged mechanical ventilation and multiple organ dysfunction syndrome than admission TCC. Our data suggest that the greatest surge of complement activation is found within the first 6 h after injury, and we argue that this time period should be in focus in the design of future experimental studies and clinical trials using complement inhibitors.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00286-3.

Multimodal noninvasive monitoring of soft tissue wound healing

Here we report results of non-invasive measurements of indirect markers of soft tissue healing of traumatic wounds in an observational swine study and describe the quantification of analog physiological signals. The primary purpose of the study was to measure bone healing of fractures with four different wound treatments. A second purpose was to quantify soft tissue wound healing by measuring the following indirect markers: (1) tissue oxygenation, (2) fluid content, and (3) blood flow, which were all measured by non-invasive modalities, measured with available devices. Tissue oxygenation was measured by near infrared spectroscopy; fluid content was measured by bipolar bio-impedance; and blood flow was measured by Doppler ultrasound. Immediately after comminuted femur fractures were produced in the right hind legs of thirty anesthetized female Yorkshire swine, one of four wound treatments was instilled into each wound. The four wound treatments were as follows: salmon fibrinogen/thrombin-n = 8; commercial bone filler matrix-n = 7; bovine collagen-n = 8; porcine fibrinogen/thrombin-n = 7. Fractures were stabilized with an external fixation device. Immediately following wound treatments, measurements were made of tissue oxygenation, fluid content and blood flow; these measurements were repeated weekly for 3 weeks after surgery. Analog signals of each modality were recorded on both the wounded (right) hind leg and the healthy (left) hind leg, for comparison purposes. Data were processed off-line. The mean values of 10-s periods were calculated for right-left leg comparison. ANOVA was applied for statistical analysis. Results of the bone healing studies are published separately (Rothwell et al. in J Spec Oper Med 13:7-18, 2013). For soft tissue wounds, healing did not differ significantly among the four wound treatments; however, regional oxygenation of wounds treated with salmon fibrinogen/thrombin showed slightly different time trends. Further studies are needed to establish standards for healthy wound healing and for detection of pathological alterations such as infection. Non-invasive measurement and quantification of indirect markers of soft tissue wound healing support the goals and principles of evidence-based medicine and show potential as easy to administer tools for clinicians and battlefield medical personnel to apply when procedures such as the PET scan are not available or affordable. The method we developed for storing analog physiological signals could be used for maintaining electronic health records, by incorporating vital signs such as ECG and EEG, etc.

Fat embolism syndrome

Fat embolism syndrome (FES) is an ill-defined clinical entity that arises from the systemic manifestations of fat emboli within the microcirculation. Embolized fat within capillary beds cause direct tissue damage as well as induce a systemic inflammatory response resulting in pulmonary, cutaneous, neurological, and retinal symptoms. This is most commonly seen following orthopedic trauma; however, patients with many clinical conditions including bone marrow transplant, pancreatitis, and following liposuction. No definitive diagnostic criteria or tests have been developed, making the diagnosis of FES difficult. While treatment for FES is largely supportive, early operative fixation of long bone fractures decreases the likelihood of a patient developing FES.

Quantification and characterisation of endothelial injury after trauma

The microenvironment theory has become very popular for providing mechanisms which explain the development of often lethal posttraumatic complications such as systemic inflammatory response syndrome (SIRS), adult respiratory distress syndrome (ARDS) and multiple organ dysfunction syndrome (MODS). With the recent advances in molecular biology and the ever-expanding understanding of trauma pathophysiology, immunomonitoring in trauma patients attempts to characterise and quantify novel molecules in order to predict patients at risk. This review article assesses the existing evidence on the biomarkers of endothelial injury and their potential utility as quantification parameters of endothelial dysfunction in trauma patients.

Prevention of fat embolism syndrome

Fat embolism syndrome is a condition of acute respiratory distress following long-bone trauma. This condition may involve not only the lungs but also a number of other body systems. The pathophysiology is not as yet clearly understood, however, intravasation of fat from long-bone fractures may play a role. Early recognition of the severity of injury both on clinical and biochemical grounds and early surgical stabilization of long bones may help to decrease its incidence. However, the best surgical technique with which to do this stabilization has not yet been clearly determined. Surgical and pharmacological techniques have been developed in an attempt to either decrease the intravasation of fat during long-bone stabilization or block the inflammatory cascade with varying degrees of efficacy. Ongoing research focuses on both the prevention and treatment of this condition.

Pathophysiology of polytrauma

Immediate and early trauma deaths are determined by primary brain injuries, or significant blood loss (haemorrhagic shock), while late mortality is caused by secondary brain injuries and host defence failure. First hits (hypoxia, hypotension, organ and soft tissue injuries, fractures), as well as second hits (e.g. ischaemia/reperfusion injuries, compartment syndromes, operative interventions, infections), induce a host defence response. This is characterized by local and systemic release of pro-inflammatory cytokines, arachidonic acid metabolites, proteins of the contact phase and coagulation systems, complement factors and acute phase proteins, as well as hormonal mediators: it is defined as systemic inflammatory response syndrome (SIRS), according to clinical parameters. However, in parallel, anti-inflammatory mediators are produced (compensatory anti-inflammatory response syndrome (CARS). An imbalance of these dual immune responses seems to be responsible for organ dysfunction and increased susceptibility to infections. Endothelial cell damage, accumulation of leukocytes, disseminated intravascular coagulation (DIC) and microcirculatory disturbances lead finally to apoptosis and necrosis of parenchymal cells, with the development of multiple organ dysfunction syndrome (MODS), or multiple organ failure (MOF). Whereas most clinical trials with anti-inflammatory, anti-coagulant, or antioxidant strategies failed, the implementation of pre- and in-hospital trauma protocols and the principle of damage control procedures have reduced post-traumatic complications. However, the development of immunomonitoring will help in the selection of patients at risk of post-traumatic complications and, thereby, the choice of the most appropriate treatment protocols for severely injured patients.

Pathogenesis and clinical relevance of bone marrow embolism in medullary nailing--demonstrated by intraoperative echocardiography

For the clarification of pulmonary impairment after medullary nailing of femoral fractures, the intramedullary pressure in the femoral cavity during the operative procedure was investigated. In addition, an intraoperative transoesophageal echocardiography was performed which revealed two phenomena occurring once the intramedullary pressure had increased: snow-flurry and configured emboli. An experimental study in sheep was performed in order to define the substrata of the sonographic echoes. The level of intrafemoral pressure which would result in bone marrow intravasation and the substrata of the echocardiographic echoes were studied in sheep by applying pressure to the femoral cavity. Sonography of the distal vena cava by laparotomy and macroscopic and histological investigation of the venous blood received throughout a proximal subdiaphragmal venotomy were undertaken. The intrafemoral pressure peaks correlated with the appearance of sonographic echoes in both patients and sheep. Snow-flurry is an indication of small amounts of bone marrow and already appears at an intramedullary pressure of 50 mmHg, which can easily occur during movement of non-stabilised fractures (values up to 90 mmHg were observed)--configured emboli consist of a core of bone marrow surrounded by thrombotic aggregate and only appeared at pressure increases of over 200 mmHg in the animal experiments. During medullary nailing in patients the intrafemoral pressure increases up to 200-600 mmHg in all reaming procedures. Configured emboli were seen in 8 of 20 patients being treated with reamed nailing. In five nailing procedures performed using the unreamed technique, no pressure increases greater than 70 mmHg and no configured emboli were observed. I.v. injected bone marrow results in pulmonary impairment.(ABSTRACT TRUNCATED AT 250 WORDS)