pathophysiology: CVA

Cerebrovascular accident or stroke (also called brain attack) results from sudden interruption of blood supply to the brain, which precipitates neurologic dysfunction lasting longer than 24 hours. Stroke are either ischemic, caused by partial or complete occlusions of a cerebral blood vessel by cerebral thrombosis or embolism or hemorrhage (leakage of blood from a vessel causes compression of brain tissue and spasm of adjacent vessels). Hemorrhage may occur outside the dura (extradural), beneath the dura mater (subdural), in the subarachnoid space (subarachnoid), or within the brain substance itself (intracerebral).

Risk factors for stroke include transient ischemic attacks (TIAs) – warning sign of impending stroke – hypertension, arteriosclerosis, heart disease, elevated cholesterol, diabetes mellitus, obesity, carotid stenosis, polycythemia, hormonal use, I.V., drug use, arrhythmias, and cigarette smoking. Complications of stroke include aspiration pneumonia, dysphagia, constractures, deep vein thrombosis, pulmonary embolism, depression and brain stem herniation.

pathophysiology: leukemia

Leukemia is malignant neoplasms of the cells derived from either the myeloid or lymphoid line of the hematopoietic stem cells in the bone marrow. Proliferating abnormal and immature cells (blast) spill out into the blood and infiltrate the spleen, lymph nodes, and other tissue. Acute leukemias are characterized by rapid progression of symptoms. High numbers (greater than 50,000/mm3) of circulating blast weaken blood vessel walls, with high risk for rupture and bleeding, including intracranial hemorrhage.

Lymphocytic leukemias involve immature lymphocytes and their progenitors. They arise in the bone marrows but infiltrate the spleen, lymph nodes, central nervous system (CNS), and other tissues. Myelogenous leukemias involve the pluripotent myeloid stem cells and, thus, interfere with the maturation of granulocytes, erythrocytes, and thrombocytes. Acute myelogenous leukemias (AML) and acute lymphatic leukemia (ALL) have similar presentations and courses. Approximately half of new leukemias are acute. Approximately 85 % of acute leukemias in adults are AML, and incidence of AML increases with age. ALL is the most common cancer in children, with peak incidence between ages 2 and 9.

Although the cause of leukemias is unknown, predisposing factors include genetic susceptibility, exposure to ionizing radiation or certain chemicals and toxins, some genetic disorder (Down syndromes, Fanconi’s anemia), and human T-cell leukemia-lymphoma virus. Complications include infection, leukostasis leading to hemorrhage, renal failure, tumor lysis syndrome, and disseminating intravascular coagulation.

pathophysiology: Hypertension (HPN)

Hypertension (high blood pressure) is a disease of vascular regulation resulting from malfunction of arterial pressure control mechanisms (central nervous system, rennin-angiotensinaldosterone system, extracellular fluid volume.) the cause is unknown, and there is no cure. The basic explanation is that blood pressure is elevated when there is increased cardiac output plus increased peripheral vascular resistance.

The two major types of hypertension are primary (essential) hypertension, in which diastrolic pressure is 90 mm Hg or higher and systolic pressure is 140 mm Hg or higher in absence of other causes of hypertension (approximately 95 % of patients); and Secondary hypertension, which results primarily from renal disease, endocrine disorders, and coarctation of the aorta. Either of these conditions may give rise to accelerated hypertension – a medical emergency – in which blood pressure elevates very rapidly to threaten one or more of the target organs: the brain, kidney, or the heart.

Hypertension is one of the most prevalent chronic diseases for which treatment is available; however, most patients with hypertension are unaware, untreated, or inadequately treated. Risk factors for hypertension are age between 30 and 70; black; overweight; sleep apnea; family history; cigarette smoking; sedentary lifestyle; and diabetes mellitus. Because hypertension presents no over symptoms, it is termed the “silent killer.” The untreated disease may progress to retinopathy, renal failure, coronary artery disease, heart failure, and stroke.

Hypertension in children is defined as the average systolic or diastolic blood pressure greater than or equal to the 95th percentile for age and sex with measurement on at lease three occasions. The incidence of hypertension in children is low, but it is increasingly being recognized in adolescents; and it may occur in neonates, infants, and young children with secondary causes.

pathophysiology: Apendicitis

Appendicitis is inflammation of the vermiform appendix caused by an obstruction attributable to infection, structure, fecal mass, foreign body, or tumor. Appendicitis can affect either gender at any age, but is most common in males 10 to 30. Appendicitis is the most common disease requiring surgery. If left untreated, appendicitis may progress to abscess, perforation, subsequent peritonitis, and death.

pathophysiology: liver Cirrhosis

Cirrhosis of the liver is a chronic disease that causes cell destruction and fibrosis (scarring) of hepatic tissues. Fibrosis alters normal liver structure and vasculature, impairing blood and lymph flow and resulting in hepatic insufficiency and hypertension in the portal vein. Complications include hyponatremia, water retention, bleeding esophageal varices, coagulopathy, spontaneous bacterial peritonitis, and hepatic encephalopathy.

Cirrhosis is known in three major forms. In Laennec’s (alcohol-induced) cirrhosis, fibrosis occurs mainly around central veins and portal areas. This is the most common form of cirrhosis and results from chronic alcoholism and malnutrition. Postnecrotic (micronodular) cirrhosis consist of broad bands of scar tissue and results from previous acute viral hepatitis or drug-induced massive hepatic necrosis. Biliary cirrhosis consists of scarring of bile ducts and lobes of the liver and results from chronic biliary obstruction and infection (cholangitis), and is much rarer than the preceding forms.

pathophysiology: CHF

Heart Failure, also known as Congestive Heart Failure, is a clinical syndrome that results from the progressive process of remodeling, in which mechanical and biochemical forces alter the size, shape, and function of the ventricle’s ability to pump enough oxygenated blood to meet the body’s metabolic requirements.

Compensatory mechanisms of increased heart rate,

vasoconstriction,

hypertrophy eventually fail,

leading to the characteristic syndrome of heart failure:

Elevated ventricular or atrial pressures,

sodium and water retention,

decreased cardiac output, and

circulatory and pulmonary congestion.

Systolic dysfunction occurs when the left ventricle is unable to relax and fill sufficiently to accommodate enough oxygenated blood returning from the pulmonary circuit. Systolic dysfunction leads to increased vascular resistance and increased afterload. Diastolic dysfunction leads to pulmonary vascular congestion.

pathophysiology: chronic Bronchitis

• Chronic Obstructive Pulmonary Disease (COPD) is a disease characterized by airflow limitation that is not fully reversible. Airflow limitation is usually progressive and associated with an inflammatory response in the lungs stimulated by irritants. COPD includes chronic bronchitis and pulmonary emphysema. Although sometimes included in COPD, asthma is a reversible disorder and is therefore considered elsewhere.


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  Chronic bronchitis is chronic inflammation of the lower airways characterized by excessive secretion of mucus, hypertrophy of mucous glands, and recurring infection, progressing to narrowing and obstruction of airflow. Emphysema is the enlargement of the air spaces distal to the terminal bronchioles, with breakdown of alveolar walls and loss of elastic recoil of the lungs. The two conditions may overlap, resulting in subsequent derangement of airways dynamics (e.g., obstruction to airflow). In pulmonary emphysema, lung function progressively deteriorates for many years before the illness becomes apparent.


• 
  The most common cause of COPD is cigarette smoking. Air pollution, occupational exposures, allergens, and infections may also act as irritants. Alpha1-antitrypsin deficient is an infrequent cause. Complications include respiratory failure, pneumonia or other overwhelming respiratory infection, right heart failure (cor pulmonale), arrhythmias, and depression.