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Table of Contents
Global Burden of Disease: Lower Respiratory Tract Infection (LRTI)
Coronary Artery Disease Powerpoint
Introduction
Global Burden of Disease
The global burden of disease measures the burden of a specific disease using the disability-adjusted-life-year (DALY) measurement. This measure combines the years of life lost due to premature mortality and the years of life lost due to time lived in states of less than full health. The global burden of disease is the highest for ischaemic heart disease or coronary artery disease (CAD). CAD is the leading cause of mortality burden, morbidity and loss of quality of life (Mathers and Loncar, 2006).
Coronary Artery Disease
Coronary Artery disease (CAD), also known as Coronary Heart Disease (CHD) and Ischaemic heart disease is the largest contributor to cardiovascular diseases (Wong 2014). The diseases are characterized by: angina (chest pain), shortness of breath and myocardial infarction which may contribute to patient mortality. One of the main causes of CAD is atherosclerosis which is characterized by gradual thickening of the coronary artery walls. This occurs when plaque, composed of debris, fat and organic substances accumulates inside the arterial walls, leading to narrowing and hardening of the blood vessels.
Other risk factors include hypertension, cigarette smoking, diabetes mellitus or elevated glucose levels, increased cholesterol levels, and obesity (Wong, 2014). Specifically, a dangerous combination of poor nutrition and lack of physical exertion can lead to many of these risk factors. Current research suggests preventive measures are the most beneficial in reducing an individual's risk for developing CAD; this includes proper nutrition and doing regular exercise. Furthermore, additional treatment options include the use of medication such as beta blockers, nitrates, angiotensin converting enzyme (ACE) inhibitors, and antiplatelets. Surgery is a more invasive option for those afflicted with multiple blockages and the goal is to improve circulation of blood towards the heart.
Epidemology
Framingham Heart Study
CAD is a major cause of death and disability in developed countries, although mortality rates have been observed to be decreasing over the last decades in western countries (Sanchis-Gomar et al 2016). Despite the decline, CAD still causes approximately one-third of all deaths in people older than 35 years. The Framingham Heart, which is an ongoing population-based cardiovascular cohort study concludes the many risk factors that contribute to CAD. The study concluded that men over the age of 38 had 1.5 times greater risk of developing atrial fibrillation than women (Benjamin et al 1994).
A follow up of the Framingham study based on 44 years of data and observation of the offspring of the original study members was conducted. Results indicated individuals aged over 40, the lifetime risk of developing CAD was 49% in men and 32% in women. The lifetime risk for 70 years old individuals was 35% in men and 24% in women. Lastly, for total coronary events, the incidence rose steeply with age, with women behind men by approximately 10 years.
Prevalence and Mortality Rate
The 2016 Heart Disease and Stroke Statistics update of the American Heart Association reported that 15.5 million people over 20 years of age in the USA have CAD, with the prevalence increasing with age for both sexes (Sanchis-Gomar et al, 2016). The results of the data collected on CAD and MI is illustrated in the graphs where the prevalence for men is observed to be much greater than women.
Furthermore, in a 2009 report based on data from National Health and Nutritional Survey (NHANES), myocardial infarction prevalence was observed in middle aged individual (35-45 years of age) during the 1988-1994 and 1999-2004 time periods. The results indicated a higher prevalence in men compared to women, but the trend declined for the former over time.
Global and Regional DALY
The World Health Organization released estimates of the global and regional burden of disease, which included 20 leading causes. The data was collected for 2000 and 2012, with a reported increase in DALY being observed both globally and in regions such as Southeast Asia, the Eastern Mediterranean and the western pacific region. The global rank of ischemic heart disease increased from being the third leading cause of death in 2000 to the first leading cause of death in 2012 (World Health Organization, n.d.) Although the global burden of coronary artery disease was dominant in western countries during the early 20th century, the burden now lies in specific Asian and middle-Eastern regions (Wong 2014). The global ischemic heart disease DALY data collected for both sexes indicates a high concentration in Central Asia, North Africa and West Europe.
Pathophysiology
Lower respiratory system (LRI) anatomy
The lower respiratory system consists of the trachea, the bronchi and bronchioles and the alveoli which make up the lungs (Medicine plus, 201). The trachea, which is the largest tube in the respiratory tract, branches off into two bronchial tubes known as bronchus. The tubes of the bronchi branch subdivide further into secondary and tertiary bronchi and then into bronchioles. The ends of the bronchioles give rise to microscopic air sacs known as alveoli. Hundreds of alveoli exist inside each lung (Medicine plus, 201).
The primary function of the respiratory system is to exchange oxygen and carbon dioxide between the body and environment and it takes place in the alveoli, also known as air sacs found in the lungs (Inglis, 2007). Therefore, the respiratory tract is constantly exposed to microorganisms such as bacteria, viruses and fungi. The majority of particles are filtered out in the nasal hairs and by the inertial impaction, which is covered by mucus found in the posterior nasopharynx. The epiglottis applies a closure and cough reflex to reduce the risk of microorganisms reaching the lower respiratory tract. However, if small enough particles have reached the trachea and bronchi they then stick to the respiratory mucus lining their walls and are propelled towards the oropharynx by the cilia. Then, antimicrobial factors such as lysozyme, lactoferrin and secretory IgA present in respiratory secretions disable inhaled microorganisms from reaching further into the lungs (Inglis, 2007).
However, particles ranging from about 5-10 µm may be able to get further into the respiratory system into the alveolar air sacs (Inglis, 2007). Once they reach the alveolar air sacs, the alveolar macrophages phagocytose the pathogens and the neutrophils may also be activated through the inflammatory response (Inglis, 2007).
Causes of LRI
Nevertheless, pathogens have developed strategies to overcome the defence mechanisms in the respiratory system. For example, Streptococcus pneumonia, a gram positive bacteria and Haemophilus influenzae, a gram-negative bacteria both produce an enzyme known as IgA protease, which is capable of disabling mucosal IgA (Inglis, 2007). Streptococcus pneumonia and Haemophilus influenzae which are primarily known to cause pneumonia, in addition to other bacteria are resistant to phagocytosis. Therefore, they are able to get passed the defence mechanisms and penetrate to the lungs. Some microorganisms also release toxins which can cause further damage to the alveolar walls (Inglis, 2007).
Pneumonia can develop after inhalation of microorganisms primarily bacteria, viruses and fungi or when bacteria from an infection elsewhere in the body spreads to the lungs, which overpower your immune system, thus infecting your lungs (Mayo Clinic, 2016). It is characterized by inflammation of the air sacs or alveoli, which are microscopic sacs in the lungs that absorb oxygen. The inflammation causes the alveoli to fill with fluid reducing the amount of air space space in the lungs for air and so the air coming is unable to exchange (Mayo Clinic, 2016).
Community and Hospital Acquired Pneumonia
Community acquired pneumonia (CAP) is the most common type of pneumonia, which occurs outside of the hospital setting. It is caused by bacteria, fungi and viruses. The most common cause of bacterial pneumonia is streptococcus pneumonia, and it usually occurs on its own or after having a cold or flu. Pneumonia caused by fungi is common in people with weak immune systems or chronic health problems and in those who have inhaled large doses of the organism. Viruses that cause cold and flu can cause pneumonia as well. In addition, viruses are the most common case of pneumonia in children (Mayo Clinic, 2016). Pneumonia occurring during a hospital stay for another illness, is termed hospital associated pneumonia (HAP). It is mostly caused by a bacteria then by a virus.The bacteria causing the pneumonia, may become resistant to antibiotics, making it dangerous.
Ventilator-associated pneumonia is a type of HAP, which occurs in patients receiving mechanical ventilation through an endotracheal tube or tracheostomy (Amanullah, 2015). Thus, the mechanical ventilation increases the risk of developing bacterial pneumonia because it allows free passage of bacteria into the lower segments of the lung through the endotracheal tube and around the cuff which then enter the lungs with each breath (Amanullah, 2015).
Symptoms
The symptoms of pneumonia can vary from mild to severe. Many of the mild symptoms are very similar to that of a cold, however they would last longer. Some of the symptoms of pneumonia may include; cough (some may cough up greenish or yellow mucus or bloody mucus) , nausea and vomiting, shortness of breath, chest pain which gets worse when you breath deeply or cough, rapid breathing, shaking chills and fever which may be mild or high (Mayo Clinic, 2016);(American Lung Association, 2016).
Diagnosing CAD
Typically, if a patient displays symptoms (shortness of breath, angina, etc) they would be referred to do one of these diagnostic tests to determine the presence of CAD. There are numerous diagnostic tests available for determining the presence of CAD, these include: electrocardiogram (ECG), echocardiogram, exercise stress test, and coronary angiogram.
An ECG and echocardiogram are both non-invasive techniques and simply image the heart at rest (Mayo Clinic, n.d.). If a patient displays symptoms during exercise, an exercise stress test may be ordered (Mayo Clinic, n.d.). All of these tests can determine if a patient has CAD but typically more testing needs to be done to be absolutely sure. If either one of these tests is positive, a patient is referred for an Coronary Angiogram which is considered the gold standard for diagnosing CAD (Bogle, n.d.).
As you can tell, many of these diagnostic techniques require complex machines and the expertise of healthcare professionals to properly determine the presence or absence of disease. The combination of these two factors may be simply impractical for many living in impoverished communities around the world. Thus, without the proper tools to diagnose CAD, the current statistics for the global burden of this disease may actually severely underestimate its truly devastating impact.
Risk Factors
Physiological Risk Factors
Although individuals of all ages can develop pneumonia, age is a factor that influences both an individual’s likelihood of acquiring pneumonia and the severity of pneumonia that develops (NHLBI, 2016). The groups with the greatest risk are individuals under the age of two or over the age of sixty-five (NHLBI, 2016). Infants are more susceptible because their immune systems are still developing, and the elderly are more susceptible because their immune systems weaken as they undergo normal aging processes (NHLBI, 2016).
Individuals can also have a higher risk of developing pneumonia if they have had a recent viral respiratory infection (such as a cold or flu), or if they have a chronic lung or other serious disease such as cystic fibrosis, COPD, diabetes, or sickle cell disease (Healthline, 2015). Diseases such as these increase risk because they make breathing difficult, block airways, and have symptoms that are similar to and can be exacerbated by pneumonia (Healthline, 2015). In addition, individuals with these diseases may also be prescribed immunosuppressant drugs such as inhaled corticosteroids (Healthline, 2015). Having a cold or flu can cause bacterial pneumonia to develop on its own, most commonly from the Streptococcus pneumoniae bacteria (Mayo Clinic, 2016).
Lifestyle Risk Factors
There are many lifestyle-related habits that can influence an individual’s risk of developing pneumonia. In healthy young individuals, smoking cigarettes is the largest risk factor for developing pneumonia (NHLBI, 2016). Alcohol abuse can also increase an individual’s chance of developing pneumonia because long-term alcohol use lowers levels of the white blood cells that can fend off pneumonia (NHLBI, 2016). Other conditions, such as having HIV/AIDS, an organ or blood/marrow transplant, chemotherapy, or long-term steroid use all increase risk as well as they weaken or suppress the immune system (NHLBI, 2016). Being undernourished can also increase risk levels for the same reason (NHLBI, 2016).
Risk can also be increased if an individual is exposed regularly to chemicals, pollutants, or fumes (WHO, 2016). Indoor air pollution caused by cooking, asbestos, or heating using biomass fuels (wood, dung) can both increase risk (WHO, 2016). Air pollution in the form of second-hand smoke can also increase an individual’s risk of developing pneumonia (WHO, 2016). Fungal-based pneumonia can also develop if an individual is exposed frequently to fungi found in bird droppings or soil (Mayo Clinic, 2016).
Healthcare Factors
Individuals may develop pneumonia while in the hospital because they have a weakened immune system and may be on immunosuppressant medication (Mayo Clinic, 2016). Hospital-acquired pneumonia can be especially dangerous because the bacteria involved may be more resistant to antibiotics because the patient is already sick (Mayo Clinic, 2016). Individuals using ventilators, which are often used in intensive care units, are at a higher risk of developing this type of pneumonia (Mayo Clinic, 2016). Bacterial pneumonia can also occur in healthcare settings such as outpatient clinics, kidney dialysis centers, and long-term care facilities (Mayo Clinic, 2016).
Treatments
CAD can be treated through pharmacological options (medications), medical procedures and lifestyle modifications. According to data comparing CAD deaths from the 1980’s and 2000, it was estimated that about 47% of the decline in CAD deaths was attributed to treatments (Llyod-Jones et al., 2010).
Pharmacological Alternatives
There are numerous medications available that are used to lower blood pressure and prevent blood clots from forming which ultimately reduces your chances of mortality from CAD. These medications include: beta blockers, nitrates, angiotensin converting enzyme (ACE) inhibitors, and antiplatelets.
Beta blockers which include atenolol, metoprolol, nebivolol and bisoprolol are used to slow down the heartbeat and improve blood flow. Whereas, nitrates, often referred to as vasodilators are used to widen blood vessels and control angina symptoms. The ACE inhibitors, one of the most commonly used drugs are used in reducing the risks of a cardiovascular event, by lowering blood pressure. They work by blocking the conversion of angiotensin-I (AT-1) into angiotensin- II (AT-II) by blocking the main effects of AT-II which are; narrowing blood vessels and water and salt retention (Brugts et al.,2012). Another type of medicine commonly used is antiplatelet medicines include aspirin. Antiplatelet medicines are known to prevent the formation of blood clots. Aspirin, the most widely used antiplatelet agent is known to reduce the risks of vascular events by inhibiting platelet aggregation (Hennekens,Dyken & Fuster, 1997).
There are numerous medications available that are used to lower blood pressure and prevent blood clots from forming which ultimately reduces your chances of mortality from CAD. These medications include: beta blockers, nitrates, angiotensin converting enzyme (ACE) inhibitors, and antiplatelets. Beta blockers which include atenolol, metoprolol, nebivolol and bisoprolol are used to slow down the heartbeat and improve blood flow. Whereas, nitrates, often referred to as vasodilators are used to widen blood vessels and control angina symptoms. The ACE inhibitors, one of the most commonly used drugs are used in reducing the risks of a cardiovascular event, by lowering blood pressure. They work by blocking the conversion of angiotensin-I (AT-1) into angiotensin- II (AT-II) by blocking the main effects of AT-II which are; narrowing blood vessels and water and salt retention (Brugts et al.,2012). Another type of medicine commonly used is antiplatelet medicines include aspirin. Antiplatelet medicines are known to prevent the formation of blood clots. Aspirin, the most widely used antiplatelet agent is known to reduce the risks of vascular events by inhibiting platelet aggregation (Hennekens,Dyken & Fuster, 1997).
Medical Procedures
Patients with severe chest pain or severe obstruction of the coronary arteries require more invasive treatment options. Currently, there are numerous surgeries which can be performed to combat CAD. These procedures include: Coronary Artery Bypass Graft Surgery (CABG), and Percutaneous coronary intervention (PCI) (Llyod-Jones et al., 2010).
CABG the most common type of heart surgery, is performed to improve blood flow into the heart. As seen in figure 11, this surgery is performed by connecting a healthy artery or vein from another part of your body such as from the leg, chest, or arm to the blocked coronary artery. The healthy artery or vein bypasses the blocked or narrowed part of the artery, thus providing a new pathway for oxygen-rich blood to flow to the heart. During CABG, the breastbone is divided and the heart is stopped to send blood through a heart-lung machine. It is important to note that bypass surgery will not cure coronary artery disease, but it will improve heart function and reduce the risk of dying of heart disease (National Heart, Lung, and Blood Institute, 2016). After the surgery, it is important that the patient takes time to recover. During the recovery period, a patient may participate in a cardiac rehabilitation program under the direct supervision of medical professionals.
As seen in figure 12, PCI, which is also known as coronary angioplasty, is a nonsurgical procedure often used to open blocked or narrow coronary arteries. The procedure requires cardiac catheterization which involves the insertion of a hollow tube (catheter) with a small inflatable balloon at its tip covered with a stent. The inserted balloon catheter then compresses the plaque and opens up the blocked artery. The inserted stent then remains in the artery holding it open (National Heart, Lung, and Blood Institute, 2016).
Life Style Modifications
Lifestyle modifications are important for both preventing, and treating CAD. They include: proper nutrition, and regular physical activity.
Nutrition
In general, avoiding a lot of red meat, sugary foods and beverages, and trying to lower your consumption of saturated and trans fat are crucial for reducing your risk of CAD. Saturated fat and trans fat, are known to raise blood cholesterol levels and thus it's important to consume more sources of monounsaturated and polyunsaturated fats which are known to help lower blood cholesterol levels. For example, avocados, salmon & trout, nuts and seeds, olive, canola, peanut , tofu are all great sources of monounsaturated and polyunsaturated fats. In addition, limiting the amount of alcohol you consume and quitting smoking, are also essential in reducing your risks of CAD (National Heart, Lung, and Blood Institute, 2016).
Physical Activity
Regular physical activity has been shown to improve symptoms and reduce mortality in patients with CAD. According to a study conducted in 2001, patients in the training group experienced fewer cardiac events and had a lower number of hospital readmissions. The total mortality of patients with CAD was found to be reduced by about 27% and 31%, as a result of the exercise training (Erbs, Linke & Hambrecht, 2006), (Jolliffe, Rees, Taylor, Thompson, Oldridge,& Ebrahim, 2001).
Future Global Burden
The global burden of coronary artery disease (CAD) is expected to increase in the future. This is especially true in developing countries due to a large population size, low education level, poor lifestyle choices and poor healthcare facilities. According to the Global Burden of Disease Study, developing countries contributed 3.5 million of the 6.2 million global deaths from CAD in 1990 (Murray and Lopez, 1996). This study estimates that the developing countries will account for 7.8 million of the 11.1 million deaths due to CAD by 2020 (Murray and Lopez, 1996). This study provides evidence for an increased economic burden of CAD from only developing countries and all the countries of the world.
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