What is Atherosclerosis?
Atherosclerosis is a disease where lipoproteins, which are plasma proteins that carry triglycerides and cholesterol, collect on the inner wall of arterial blood vessels. It is a chronic inflammatory response in the walls in which the lipoproteins harden and form plaque within the arteries. There are three different types of atheromatous plaque. One type is simple cholesterol crystals that build up along the wall and narrow the diameter of the artery. The second type is called an atheroma, which is a nodular accumulation of flaky, yellow material (which is composed mostly of macrophages) in the center of large plaques at the lumen of the artery. The last type of atheromatous plaque is calcification of the outer base of more advanced lesions.

Atherosclerosis is caused by many factors, some of which can be controlled by the patient. Hypertension, obesity, smoking, diabetes, high cholesterol, and congenital heart disease can all be individual or combined causes of atherosclerosis in a patient. Depending on where in the body plaque builds up, symptoms may include angina, heart attack, severe pain, stroke, and/or dizziness.

Significance of Atherosclerosis
Atherosclerosis progresses slowly and is cumulative over time, beginning with macrophage infiltration into the artery. A fatty streak results and a lesion advances to eventually create an atheroma, as shown in the figure below. This continues to advances to create a larger, more complicated lesion. Over time, if the lesion is not treated, the plaque will suddenly rupture and form a thrombus that severely slows down, or even stops blood flow. This can lead to an infarction, which is death of the tissues feeding off of the artery within five minutes if it is not tended to immediately.

In the United States alone, atherosclerosis leads to the death of almost 15,000 people every year. It is also the cause of hospitalization for 20,000 patients per year and over 730,000 physician office visits per year.

Current Treatments
Current treatments include improvements in diet, cholesterol reduction medication, anticoagulate medication, blood pressure medication, surgical procedures and sometimes even gene therapy. Our medical device plans to make improvements upon the current surgical procedures, which are endarterectomy, angioplasty, bypass surgery, and thrombolytic therapy.

In my previous article, The Basics of Heart Failure, it was mentioned that a ventricular-assist device (VAD) is the primary treatment for heart failure. Dr. William Wagner (who also contributed to the positive displacement pump technology previously mentioned) believes that there is much room for improvement in the biocompatibility of VADs. he spoke at the BMES conference of infection and thrombosis (blood clotting) problems upon implantation of VADs into patients.

Infection due to VADs can be caused by the biomaterial used, poor sterile technique, device failure, and percutaneous line design. Shear forces caused by excessive bleeding upon implantation of the device can also cause infection, and infection leads to tissue necrosis.

Thrombosis and thromboembolism are problems that all devices face when coming into contact with blood. To avoid this issue, surgeons use drugs like Heparin or Coumadin to avoid coagulation when devices come into direct contact with the blood.

Many scientists believe that nothing can be solved unless it can be quantified. Infection and thrombosis (believe it or not) can be crudely measured through microembolic signals (MES). Dr. Wagner suggested that scientists should get more out of animal models by analyzing MES, explants, and gross neurological health more thoroughly to minimize plately aggregation and avoid thrombosis. An example of a thoroughly tested device that has been underway for 30 years is the Heartmate II, which is implanted in the chest to aid the heart in pumping (shown in the figure above). This device can be used as a treatment method for patients with severe heart failure, or as a bridge until a transplant is available. When tested in calves, this device showed a spike in platelet aggregation (which is expected and normal) and then a steady decrease in aggregation due o microaggregates leaving the implant site. In previous VADs, the platelet aggregation spiked and then didn’t decline at a steady enough rate for thrombosis to cease. Another research project underway by EvaHeart to improve the downfalls of VADs is to replace bovine (cow) with ovine (sheep) products due to this superior configuration of ovine tissue (methacryloyloxyethyl phosphorylcholine).

-Amy

Heart failure (HF) is a condition in which the heart’s ability to fill or pump a adequate amount of blood is impaired. It can be caused by a number of factors including hypertension (high blood pressure), valve failure, coronary artery disease, and many more things. In the figure below, heart failure is shown to be caused by thickened myocardium (myocarditis), which may be a direct result of a viral infection that can cause the muscle to become inflamed. Almost 2% of the American population has heart failure and even with the best therapy, HF still has an annual mortality of 10%.

Treatment of HF depends on the stage of the disease’s progression and is rated on a scale from case I to case IV. The five year survival rate of patients in stage IV is only 20%, therefore this is considered severe heart failure. There are several minimally invasive devices used in HF treatment. The most common treatment device is an artificial pacemaker (shown below), which successfully prevents about 50% of all heart failures from re-occurring. Another treatment option for HF that is extreme is a heart transplant. This is called the “Gold Standard” treatment because it is the best to use, however the availability of donors is slowly declining while the number of patients who need a transplant is steadily rising. Only about 2200 heart transplants are preformed every year.

The ideal solution would be an artificial heart…In 1985, at the University of Pittsburgh Medical Center (UPMC), the first artificial heart was implanted. Five years later, UPMC was the first medical institution to release a patient with a ventricular-assist device (VAD) (shown below). Today, VADs called positive displacement pumps are the leading treatment therapy for HF patients. Dr. Marc Simon presented the idea of positive displacement pumps at the BMES Conference and spoke of future improvement for these devices. He announced that second and third generation prototypes are currently underway in many institutions and will be ready for release soon. Dr. Simon discussed that there is an ideal period during HF in which it is ideal to implant there devices into the patient in order to maximize recovery success. There is a certain point in HF in which an acute, catastrophic event leads to sudden progression of the disease, eventually leading the patient to death. The closer researchers are able to pinpoint the time immediately prior to this turn of events to implant the device, the greater the patient’s chances are for survival.

-Amy

When preforming surgeries, an obstacle that has to be dealt with is making sure that the patient;s blood doesn’t coagulate (or thicken) when it comes into contact with metal intruments. This is currently dealt with by a drug called heparin, which thins the blood so that it doesn’t have an adverse reaction to the touch of an instrument. Heparin is widely used and is successful…most of the time. It creates negative reactions in three to ten per cent of all patients in which the blood will coagulate and clot up all around an instrument as soon as direct contact is made. The image below shows that when Heparin fails, coagulation occurs and the device used in surgery is covered with blood clots:

At Brigham Young University, BYU, an alternative solution has been found. Dr. Kenneth Solen and Jared Parker, biomedical engineers who have dedicated much time to this problem, believe that a different type of precaution needs to be taken. They suggested that rather than adding something to the blood that may induce an immune reaction, they would like to remove something. There exist specific proteins in the blood that carry a strong electrical charge in order to cause coagulation. One could conclude that to remove these proteins, something with a negative charge must be utilized. Therefore, the research team used a negatively-charged gel to attract and remove these coagulation proteins, while leaving the rest of the neutral and negatively-charged proteins in the blood. In the lab, this was proven to be successful, however human testing has not been conducted yet. Dr. Solen continues to pursue the perfection of this innovation at W.L. Gore.

After Dr. Solen’s anticoagulation method, the device used in surgery remains clear of blood clotting:

I would like to thank Blake Ferguson for sharing this article with me.

-Amy

Coronary Artery Disease and Coronary Bypass Grafting

Coronary artery disease (CAD) is the leading cause of death for both men and women in the United States. The process of atherosclerosis is the hardening of an artery due to a lipid build up, resulting in functional loss. Fatty deposits, or plaques, may accumulate inside the arterial wall and cause stenosis, or an abnormal narrowing the artery wall. This causes the flow of blood to be reduced or completely stop and the vessel wall to lose its flexibility and ability to handle pulsatile flow. There are several forms of treatment available for CAD depending on the severity of the disease, including lifestyle changes, medicines, angioplasty, and coronary artery bypass grafting (CABG).

CABG is the preferred treatment for patients with multiple areas of coronary artery narrowing or blockage and also for patients with higher percentages of stenosis, this relation can be seen in figure 1 above. Patients typically have 1 to 5 bypasses within one surgical procedure. This form of treatment is the most common type of surgery in the United States, with about 500,000 surgeries per year. Typically, the patient’s saphenous vein from the leg, internal mammary artery (IMA), or the radial artery from the arm is used. Figure 2 shows the location of the saphenous vein and IMA. These vessels are removed and grafted onto the hardened artery to revascularize the affected area.

Figure 2

Advantages and Disadvantages of the Current Gold Standard

The current gold standard for the CABG procedure is the use of autologous (from self) saphenous vein and IMA because of their resemblance to the native coronary artery and their relatively high patency rates. It was not until recently that the radial artery has been widely studied as another source for this procedure. The five and ten year artery patency rates for these have all shown to be greater than 70% and 50%, respectively. These rates vary depending on the blood vessel used for the procedure.

Even with the success this procedure has had, there are several disadvantages that may lead to complications. Removing an autologous vein for the procedure may cause donor site morbidity, which can lead to problems such as groin infection near the site of the saphenous vein removal. In addition, there is only a limited supply of donor vessels for this procedure. Up to 30% of patients undergoing lower limb bypass do not have a suitable vein. This can be problematic for patients who need multiple CABGs or have had previous procedures. There is also a greater risk with the use of multiple vessels. For example, there are more incidents of deep sternal wound infection when both IMAs are used for this procedure, especially for patients with obesity and diabetes.

Existing Vascular Grafts and Improvements

Although living autologous vessels seem to be the ideal conduits for CABG, there are several factors, as discussed above, which have prompted efforts to develop a more suitable donor vessel. The ideal blood vessel substitute should mimic the characteristics of a native blood vessel, including its composition, structure, function, and mechanical properties. It should be durable enough to endure the mechanical stresses, as well as the threat of biodegradation and infection within the body after implantation. The vessel should be made up of materials that promote cell-specific interactions and needs to be able to have similar viscoelastic properties as a normal artery to avoid a compliance mismatch. It should be flexible in order to maintain its contour, yet rigid enough to prevent kinking. The materials used, especially on its luminal surface, must be nonthrombogenic to prevent blood clotting in the vascular graft. It is favorable that the vessel is easily and quickly manufactured, and should be readily available in multiple lengths and sizes.

However, no existing conduit possesses all the properties and qualities of the ideal arterial vascular graft listed above. Current alternatives to autologous vascular grafts are prosthetic conduits based on expanded polytetrafluoroethylene (ePTFE) and polyethylene terephthalate (Dacron ®). Their patency at 5 years is 40% to 50%, which is acceptable but relatively low. Tissue engineering has proven to be successful in wound management, burns, and cartilage repair; therefore their has been a growing interest in designing biological blood vessels as an alternative to autologous vascular grafts and current prosthetic conduits. However, previously proposed and designed tissue engineered vascular grafts were not durable, were prone to early thrombosis, and had poor patency rates. This means that a new vascular graft with all the above mentioned qualities is yet to be manufactured, but is a hopeful potential cure for the future.

Sleep apnea is a disorder in which pauses in breathing occur for about 10 to 30 seconds during one’s sleep (American Academy of Family Physicians 2005). An “apnea” is an episode without breath in which one’s body simply skips breathing momentarily. Of the 18 millions Americans that have sleep apnea, 90% don’t even know they have it because they don’t recall waking up hundreds of times during the night due to a break in REM sleep. They feel tired and moody during the day, craving the occasional morning, afternoon, and evening nap; but they often don’t realize that they’re suffering from a disorder. The best means for diagnosis of sleep apnea is an overnight polysomnography that tracks blood pressure (BP), respiration (resp), sympathetic nerve activation (SNA), and body movements (Benedictis 2006).

There are two types of sleep apnea: obstructive and central. Obstructive sleep apnea (OSA) occurs in one out of every five people and is caused by an obstruction in the throat. The obstruction is any physical hindrance in the airway, this can be caused by anything from obesity to enlarged tonsils. People who are more vulnerable to OSA are men, overweight individuals, and individuals over the age of 40. Central sleep apnea (CSA), the main focus of this paper, is caused by an error in the thalamus, the part of the brain that controls involuntary breathing. During CSA, there is no effort by the person’s body to breath; no struggle by respiratory muscles, just stiffness of the body without breathing. Mixed apnea, which is a combination of OSA and CSA, also exists (UMMC 2004, ASAA 2007).

Circadian rhythm sleep, or “normal sleep”, consists of a period of time in which the body is at rest to avoid exhaustion (UMMC 2004). During circadian rhythm sleep, one exhibits tidal breathing in which about 700 mL of air is inhaled and filtered through the lungs for oxygen extraction before exhalation. During circadian rhythm sleep, one’s body should comply with average standards such as an average pulse rate between 60 and 80 beats per minute and average resting blood pressure around 120/80 mmHg. The average respiratory rate for a resting adult is between 12 to 18 breaths per minute; however children take about 20 to 30 breaths per minute (UI Health Care 2005). There are two major respiratory gases: oxygen (O₂) and carbon dioxide (CO₂). The average amount of oxygen in expired breath during tidal breathing is 250 mL of oxygen per breath and for carbon dioxide it is 220 mL of carbon dioxide per breath (George 2007). The average blood pH for a resting adult is 7.35 to 7.45 and red blood cells should be about 33% concentrated with hemoglobin (Hb) (Encyclopedia of Surgery Information 2005).

Proposed Solution

Apneas disturb circadian rhythm sleep and cause the individual to wake up in the night gasping for air. During an apnea, the individual’s pulse, blood pressure, and respiratory rate decrease and they submit to hypoxia (lower than threshold oxygen levels) and hypercapnia (high carbon dioxide levels) (ASAA 2007). There are several risks to people with sleep apnea, among these are higher risks of car accidents due to drowsiness, stroke due to increased blood viscosity, depression due to lack of sleep and low sexual arousal, heart disease, heart attack, heart failure, kidney failure, seizures, headaches, eye disorders, and memory loss. According to doctors at the University of Maryland Medical Center, people with sleep apnea must be diagnosed and treated to help reduce their chances of these terrible risks (Rice et al. 2006).

After diagnosing a patient with OSA, doctors will recommend a series ideas that will help reduce the amount of apneas a person has. There is positional therapy, dieting, exercising, and surgery. The 20% of the American population with OSA has great chances to permanently correct their disorder by simply losing weight, surgically widening their airway, or surgically moving their jaw forward (Rice et al. 2006, ASAA 2007).

The first thing a doctor will say to their newly diagnosed CSA patient is to avoid alcohol and central nervous system depressants because they worsen CSA by relaxing the muscles and impairing the brain. When looking at CSA, there are many solutions available to relieve it, however none of the devices on the market are a permanent cure for this disorder. In order for a device to help the individual, it must first detect an apnea and then trigger a mechanism to induce breathing without waking them (ASAA 2007, Encyclopedia of Surgery Information 2005).

Some currently patented detection devices are adaptive servo-ventilation devices, snorkels, and sleep apnea detection apparatuses. Our company’s proposed detection device for CSA will be a pulse oximeter, which utilizes infrared light shining through one’s finger to measure the Hb concentration on red blood cells.

A pulse oximeter clips onto the patient’s finger and can be kept on for the whole night. It will sense Hb concentration below 33%, which correlates with hypoxia below 75% O₂ saturation on red blood cells. When O₂ saturation drops below 75%, the photodetector senses an increased amount of infrared light, so the pulse oximeter can trigger the device to induce breathing.

Pulse oximeters are the best detection device because they are comfortable, don’t dry skin out/chaff, are used widely in hospitals, and don’t cause claustrophobia since they are not on the person’s face. For people who move around in their sleep, our company can provide an add-on option to the pulse oximeter that utilizes Bluetooth technology to communicate with the breath induction device rather than a wire. Pulse oximeters are accurate in detecting hypoxia about 80% of the time (AARC 1991, UMMC 2004).

Examples of breath induction devices for CSA patients are continuous positive airway pressure (CPAP), electrical stimulators, and drugs. The most common breath induction device is the CPAP, which delivers a constant flow of air pressure using a nasal mask while the patient is sleeping. Since it is unnecessary to continuously apply pressure to the airway even when the patient is not having an apnea, the R&D department of our company should conduct research to create a positive airway pressure device that administers pressure only when activated by the pulse oximeter (if our company chooses to invest in sleep apnea). CPAP is the most widely used and accepted method for CSA patients because it effectively prevents the patient from having an apnea due to its continuous pressure, thereby providing the patient with smooth respiration throughout the night (Matthews 2003).

On the negative side, the CPAP can cause claustrophobia, dry skin, and discomfort. It is also very large, must be cleaned/maintained meticulously, and cannot be kept in direct sunlight or exposed to excessive amounts of heat. There are several different types of CPAPs like the Auto-CPAP, Smart CPAP, and Goodnight 420E. Our company will use the Auto-CPAP because it is more compact and lightweight than the others, automatically adjusts to altitude changes, and has a display screen that is very user friendly (REMstar 2006).

Our company’s proposed solution consists of a pulse oximeter that detects low Hb/oxygen levels and a CPAP that induces breathing through constant pressure on the airway. This solution works via the feedback loop in figure 5. Although the detection method is wonderful, the breath induction method is already widely in use with many established competitors. Our company should not invest in a sleep apnea device patent because, although the pulse oximeter can cost as low as $80, the CPAP alone is around $800 each at leading companies. A good investment for our company could be not to create a patent, but to have the R&D department create a better CPAP device than leading companies. In conclusion, a patent for a sleep apnea device is not currently a good investment for our company (AARC 1991, Rice 2006, REMstar 2006).

-Amy Shah

Americans donate roughly twelve million units of blood per year. These units are then processed into 20 million blood products that are to be transfused to millions of people in the United States¹. This is an amazing miracle for patients with injuries that involve extensive blood loss, however donor blood may possess contaminants that are harmful to the human body. Many contaminants have been identified and have cures or solutions. Yet, more and more contaminants that threaten the U.S. blood supply are being discovered every decade, some more vital and deadly than others. Technologies are being developed to save the most lives possible and prevent complications through blood transfusions.

In ranking the emerging threats to the U.S. blood supply, there are four main criteria that need to be considered. First, there is the ability of the contaminant to survive in refrigerated blood for a number of days². Second is the amount of patients susceptible to infection when administered the given agent through blood transfusion and the impact of the symptoms caused by infection². Next, the presence and length of an asymptomatic phase in which the infectious agent is resides in the bloodstream². Lastly, the prevalence of infection in the donor population is vital². The threat of the agent contaminating the blood supply is statistically much less if the occurrence of infection in the general population is very small.

American trypanosomiasis, more commonly referred to as Chagas Disease, is transmitted in humans by the Trypanosoma cruzi parasite³. It causes illness for 4 to 8 weeks, and in 20-30% of infected patients can potentially lead to fatal cardiac disease and gastrointestinal problems later in life⁴. Chagas Disease can be transmitted in three ways: through the bite of an infected triatomine insect, by an infected mother giving birth, or via blood transfusion. Although this disease is limited to North and South America, it is prevalent in 21 countries³. Infection rates can range anywhere from 0.1% in Argentina to 24.4% in Bolivia⁵. Chagas Disease is usually only found in rural areas, yet due to economic and financial rationale, many people living in rural areas are moving into urban areas. This increases the risk of infection by blood transfusion. Studies have shown that about 1 in 25,000 U.S. residents are infected with the protozoan and in areas with high Latin immigrant populations, such as Los Angeles and Miami, the prevalence is estimated to be 1 in 7500 and 1 in 9000 respectively². Chagas is the top threat to the U.S. blood supply because of its potentially severe symptoms, its transmissibility by transfusion, and its relatively high presence in the U.S. population. Vector control and blood screening are the two main ways to prevent further spread of this disease. Vector control has been quite successful. This is the effort of people trying to restrain carrier animals/insects from infecting humans. Countries involved in this have spent over 400 million dollars on vector control of the Chagas disesase⁵. Blood screening can also be an effective method. It can identify the specific antigen for Chagas disease in any blood sample. A downside to blood screening is that it’s only mandatory in 10 of the 21 countries Chagas dominates⁵. Two relatively new drugs (nifurtimox and benznidazole) are known for being able to cure 50% of infections. These drugs are active in the acute phase of Chagas, but have little activity in long-term chronic forms of the disorder. Use of these drugs has been limited because they have serious side-effects, are extremely expensive, and they haven’t been registered in most countries yet⁵.

Creutzfeldt-Jakob Disease is a rare and incurable brain disorder with a dire prognosis⁶. CJD is acquired by humans who consume the meat of bovine infected with Transmissable Spongiform Encephalopathy (TSE, also known as Mad Cow Disease)⁴. It is transmitted through prion, a protein with an abnormal structure, which is found in the brain. Prion refolds native proteins into a diseased state, causing them to lose their function and eventually die⁶. Prion grows exponentially, so it has the potential to kill its victim in as little as two months! There’s a classical CJD and an emerging variable CJD. vCJD has slight characteristic differences and is often found in younger patients⁶. It has a very long incubation period, up to 20 years. This poses a great risk because someone could donate blood without knowing they have the disorder. Studies have shown that transfusion of the disease is possible in sheep, and while it has not been confirmed that transfusion is possible in humans, there have been three reported cases⁷. Worldwide, 157 cases of the disease have been reported, none of which occurred in the United States⁷. Although the prevalence of the disease is not high (especially in the U.S.), it is ranked the second highest threat to the blood supply because it has recently been reported that some U.S. cows are infected with TSE. The disease can be diagnosed by electroencephalography, cerebrospinal fluid analysis, and MRI⁶. Cannibalism, hormone products corneal grafts, and implanted electrodes are associated with transmission of CJD⁶. A way that this deadly disease can be prevented from spreading is to ban blood donations in the United Kingdom from anyone that has received a blood transfusion before 1980⁶. Since there is an asymptomatic period of vCJD, it is wise to control the spread through blood transfusion by simply banning all those who are a potential risk.

Severe Acute Respiratory Syndrome is characterized by fever and severe respiratory symptoms and had a 7-15% fatality rate². There have been no documented cases of SARS in the U.S., however the high incidence of this disease in Asia and areas of Canada leaves room for a potential U.S. outbreak². Although SARS is a respiratory disorder, there have been documented cases of viremia. This means there was presence of the agent in the bloodstream, therefore transmission by transfusion exists². Since SARS could potentially become prevalent in the U.S. in the coming years and has the potential to be transmitted through blood transfusions, it is the third highest risk to the blood supply. There are several screening methods that can be used to reduce the risk of obtaining SARS-infected blood. Although SARS is a respiratory disease, it has a viral phase and possesses viral RNA that can be detected by reverse-transcriptase polymerase chain reaction⁸. PCR is a specific test, but not very sensitive. A positive test result will accurately indicate an infected sample, but a negative result does not necessarily indicate a clean sample. PCR is also relatively expensive and requires specific equipment and expertise¹¹. Another diagnostic test is an enzyme-linked immunosorbent assay test that can detect antibodies prevalent to SARS. ELISA uses an antibody specific to the SARS-relative antigen and another antibody causes a chromogenic or fluorogenic substrate that produces a signal. This test is much cheaper than PCR, and more sensitive in detecting SARS⁹. An immunofluorescence assay can also detect antibodies of the disease. Immunofluorescence labels antibodies or antigens that are produced due to the presence of SARS CoV and labels them with fluorescent dyes that can be detected with a special microscope¹⁰. Moreover, pre-donor screening to avoid any possible risk of infected blood should include white blood cell or platelet count. Suggestive alerts for SARS, besides visible symptoms, include low white blood cell and platelet count and high levels of lactate dehydrogenase, creatine kinase and C-reactive protein¹¹.

The next category of contaminants to the blood supply pose a medium risk because they are either less transmissible through blood transfusion or have non-severe complications associated with infection. The first disease of this category is Human Herpes Virus 8 (HHV-8). It is linked to Kaposi’s sarcoma, body cavity based lymphoma, and Castleman’s disease. Of all anatomic sites, the presence of HHV-8 is found most frequently in saliva¹². It’s transmitted mainly through sexual contact, although it is suspected to have the potential to be transmitted through blood transfusions as well⁷. Data shows that approximately 3% of donors in the U.S. carry HHV-8 in their bloodstream⁷. Due to the significance of its resulting diseases and prevalence in the population, HHV-8 is a significant risk to the U.S. blood supply. Nonetheless, it is considered a medium risk because incidence of transfusion is rare. One present examination for HHV-8 transmission involves testing plasma/serum samples. HHV-8 serostatus is measured with an enzyme immunoassay (EIA). The assay detects antibodies to most structural and non-structural antigens present in HHV-8 virions. Transmission risk may also be reduced through routine procedures that remove most circulating B lymphocytes. Acellular blood products have few lymphocytes, thereby conveying a lesser risk¹³. The next disease is Babesiosis, a parasite infection from a tick bite that is similar to malaria⁷. It only causes mild flu-like symptoms in most people but could be deadly to immunocompromised patients⁷. Studies have shown that it can survive in erythrocytes for up to 35 days and there have also been 40 reported cases from blood transfusion since 1980, however there is no current test to screen for babesiosis⁷. Since the disease can be transmitted through blood transfusion and there is no test for it, babesiosis poses a strong risk, however its mild symptoms place it lower on the threat list.

The final category of threats to the blood supply involves the low risk agents. These include, in order of risk, the bacteria Anaplasma phagocytophilium and Ehrlichia chaffeensis, and the virus Hepatitis G. A. Phagocytophilium is acquired by humans primarily through the bite of a tick and causes mild flu like symptoms but potentially causes severe complications and even death in 5% of the infected. It has been determined that it can survive in blood for 18 days, however there were only 351 cases of it in the US in 2000². It is suspected that the bacteria can be eliminated as a threat in stored blood by the use of leukoreduction filters². E. Chaffeensis has virtually the same incidence of infection and characteristics as A. Phagocytophilium, however there are not severe complications that occur with its infection making it less of a threat². These two were low on the list because of their lack of occurrence in the population, low severity of complications, and the potential that exists for their threat to be eliminated by the use of filters. Hepatitis G is a viral strain that has not been found to have any effect on humans, although it is suspected that it could lead to post-transfusion hepatitis⁷. It can be obtained even though the transfused blood shows negative for Hepatitis A, B, and C. Some believe that the G virus is associated with liver disease, but many researchers are also doubtful that it causes any illness at all¹⁴. Currently there is no treatment available for Hepatitis G and the etiology is unknown. It is very similar to Hepatitis C and is seen in 20% of patients with any type of Hepatitis, therefore it is believed to possibly be a co-infectant with other Hepatitis viruses¹⁵. Currently the only method of detecting Hepatitis G is through a costly DNA analysis that is not widely available, but there is a strong effort to develop a test for the antibody of this mysterious virus^15. Because there are no affects associated with the viral infection it must be considered the lowest risk of potential emerging threats to the U.S. blood supply.

One of the most common obstructions of blood transfusion is bacterial contamination of blood. Bacterial contaminants can result in septic reaction and even death of the blood recipient¹⁶. This type of contamination is considered the second most common death from transfusion in the U.S. Fatality rates are raising from one death in every 20,000 donor exposures to one in every 85,000¹⁷. Due to the bacteria that have be already been found, new bacteria have been pre-conditioned to proliferate faster than older ones. Bacteria have also formed the most optimal structure of DNA to resist anti-septic protocols. For instance, it is estimated that the level of contamination of bacteria is very low, about 1 to 10 colony units bacteria per mL, but with the appropriate media and temperature, these bacteria can divide and proliferate at a high enough rate to reach 10⁶ units/mL within several hours¹⁷! The most common cases for bacterial contaminations are: donor bacteremia (blood donors are either asymtomatic or in recovery phase of a bacterial infection), contamination during within the skin or needles while blood is being withdrawn, and contamination of an improperly prepared blood bag¹⁷. Therefore, donated blood with pre-screening still has chances of re-emerging threats for blood transfusion. Based on these common contamination risks, the general solutions for bacterial contamination are: to strictly follow anti-septic procedures for needles and skin regions that are being exposed to blood, take considerations when choosing blood bag and the contamination level, and material being made for blood bag for the optimal storage solution with the least contamination. Pre-detect any bacterial existence by measuring the amount of oxygen being consumed or the amount of CO₂ being produced by sensitive micro detection equipment. Finally, the donated blood can be scanned by “pathogen inactivation,” which uses pathogen reduction devices combined the use of psoralen and ultraviolet A light, riboflavin and visible light, ultraviolet B irradiation, and the addition of methylene blue or phthalocyanines with visible light. These combinations will inactivate the bacterial proliferation. Thus, they will be reduced as these lights are scanning through the platelets which they thrive on¹⁷. Blood bags should be stored at very low temperatures (about four degrees celcius) ¹⁷. All these precautions should be taken to minimize bacterial contamination.

The application of microarray technology to blood testing would be a revolutionary advancement. It would provide an integrated platform for comprehensive testing of donor and donation replacing multiple individual assays¹⁸. Researchers are currently trying to achieve a system of implementing microarray technology to screen a blood sample for various impurities and diseases all at once. Such a system would simplify and improve the efficiency of blood screening and has the potential to reduce the cost and time of multiple tests¹⁸. The microarray technology would use an antigen microarray consisting of glass slides dotted with thousands of proteins and other molecules that are attacked in autoimmune diseases¹⁹For the microarray technology, doctors will draw a blood sample from the patient and incubate it on the array. The antibodies target corresponding molecules on the array and attack them. Then fluorescent molecules are added to create colored spots on the slide that detect which antibodies attacked their molecules. The doctor or lab analyst then counts the spots to observe which antigens the immune system responded to¹⁹. In an unaffected, healthy patient, the antibodies will ignore the majority of the antigens on the array. In diabetic patients, the spots on their array will correspond to pancreatic cell proteins. In patients with rheumatoid arthritis, the spots will correspond to molecules found in joints of the body¹⁹. Due to large data sets generated by the chips, new statistical and informatics-related challenges have risen. This makes microarray technology is a victim of its own success. Novel statistical methods need to be innovated for analysis of these plenteous and diverse data sets²⁰. There is no standard system for generally managing and providing an expenditure of microarray techniques or their applications²⁰. Although this technology will allow the application of new insights, its potential is limited by the constraints mentioned above. Microarray technology will most likely revolutionize the bio-medicine field in upcoming decades. This tool will help mankind understand more about life on planet earth, but it has also taught us that we have much more to learn in years to come.

With all the tests and solutions to improve blood transfusions, sometimes there’s simply not enough time to get blood to a victim. In these distressing cases, one cannot bleed to death until donor blood arrives to them, so there are temporary solutions. Currently, there are no artificial blood substitutes available on the market, however there is a partial substitute. This blood substitute contains artificially engineered hemoglobin and can carry oxygen throughout the body sufficiently. Although oxygen can be distributed to limbs and various other parts of the body by this innovation, it cannot carry nutrients. Therefore it hasn’t been approved for the market²¹. Potential uses including trauma, various surgeries, angioplasty, and oxygenation of tumors during chemotherapy or radiation. Also, the product can be made available on the battlefield, at the scene of accidents, and stored in emergency vehicles/departments²¹.

All in all, there are many modern dangerous contaminants that threaten the U.S. blood supply. Still, there are precautions and tests that can be taken to prevent the further spread of them through blood transfusions. New tests and technologies, such as microarray technology and artificial blood substitutes, are being improved to perfection everyday. Mankind’s potential to overcome these obstacles are endless.

This paper is a collaborative effort by Amy Shah, Bao Dinh, Jonathon Hwee, Andrew Keebaugh, and Brian Rinaldi