The Institute of Medicine (IOM) released a report last week summarizing a project that examined the impact of nutrition on head injury. The Department of Defense requested this review because of the significant morbidity and mortality incurred by our armed forces caused by TBI.
The IOM convened a panel of experts that reviewed the available data. As with most such panels, there is a recommendation to engage in additional research. They went a step further, though, and recommended several specific avenues of research, including:
Determine optimum levels of blood glucose
Study the benefits of insulin therapy
Determine the optimal goals for nutrition
Look at the effects of supplements and various diets, CDP-choline, creatine, n-3 fatty acids, fish oil and zinc supplements
The most pressing recommendation they made was a call to standardize the feeding regimen for severe TBI patients very early after injury. Specifically, they recommend that nutritional support be started within 24 hours of injury, consisting of 50-100% of the total energy expenditure with 1 to 1.5 g protein per kg body weight. This should be continued for the first 2 weeks after injury. It appears that this intervention limits the intensity of the inflammatory response after TBI and improves outcomes.
The photo from last Thursday showed fat emboli manifesting as petechial skin hemorrhages. Classically, fat embolism presents as a triad of mental status changes, pulmonary insufficiency, and petechiae. Typically, these manifestations show up after 2-3 days, although in severe cases, they may occur sooner.
The traditional gold standard for diagnosis of vascular injury to the extremities has been a good physical exam plus conventional catheter angiography. However, using angiography always adds a layer of complexity and risk to patient care. The interventional team may not be immediately available after hours, there is typically a road trip within the hospital to deliver the patient for the study, and overall it is quite expensive.
With the advancements we have seen in CT angio techniques and scanner technology, some centers have been using computed tomography to evaluate for vascular injury. A few small retrospective studies have been done, but this month a larger prospective study was published.
Over a 20 month period, 635 patients with extremity trauma and a suspicion for vascular injury were entered into the study. A structured physical exam was performed, and any patient with “hard signs” of vascular injury were taken to the OR. 527 patients had no signs of vascular injury and were observed and released. The remaining 73 (most had soft signs of vascular injury) underwent CT angiography of the extremity.
The sensitivity and specificity of this test were 82% and 92%, respectively. Positive and negative results were nearly perfectly predictive. However, approximately 10% were inconclusive, usually due to bullet artifact or reformatting errors. These patients either underwent confirmatory conventional angiography or operation.
Bottom line: Angiography using multi-detector CT scanners is an excellent tool for evaluating potential extremity vascular trauma from penetrating trauma. The technology is available around the clock without a wait, and usually does not involve lengthy trips through the hospital. A good physical exam is imperative so patients with hard signs of injury can go straight to the OR. Equivocal studies must be evaluated further by conventional angio or an operation.
A New Method For Killing Antibiotic Resistant Bacteria
IBM and the Institute for Bioengineering and Nanotechnology have developed a novel way of wiping out antibiotic resistant bacteria like MRSA. They created a type of nanoparticle that is activated by contact with water. When this occurs, it self-assembles into a new polymer structure that is attracted to infected cells and bacteria, but not healthy cells.
Changes in electrostatic charge on the cell surface attracts the nanoparticles, which then physically break through the cell walls and membranes of bacteria. The nanoparticles then degrade and are excreted.
Bottom line: This is a very exciting line of research. Bacteria multiply and evolve rapidly, sharing genetic information that allows them to change their biochemistry and become resistant to our usual antibiotics. Since the destructive process used by these nanoparticles is purely physical and not biochemical, it will be extremely difficult for any type of resistance to develop. This is an important advance in our efforts to control pathogens.
Reference: Biodegradable nanostructures with selective lysis of microbial membranes. Nature Chemistry, April 3, 2011 (online).
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