Hemodynamic Disorders 3 PDF

Hemodynamic Disorders 3 Fat Embolism Air may enter the circulation a. During obstetric procedures(‫)عمليات نسائية‬ -Occurs in 90% of individuals with b....

Hemodynamic Disorders 3 Fat Embolism Air may enter the circulation a. During obstetric procedures(‫)عمليات نسائية‬ -Occurs in 90% of individuals with b. Chest wall injury. severe skeletal injuries (long bone c. A particular form, called decompression fracture) but less than 10% show any sickness, occurs when individuals are exposed to clinical findings. sudden changes in atmospheric pressure - Fat microemboli occlude pulmonary and cerebral microvasculature decompression sickness Fat embolism syndrome: -Deep-sea divers, and underwater construction - pulmonary insufficiency. workers are at risk. - Neurologic symptoms. When air is breathed at high pressure - Anemia. (e.g., during a deep-sea dive), increased amounts of - Thrombocytopenia. gas (particularly nitrogen) become dissolved in - Diffuse petechial rash. the blood and tissues. - Fatal in 10% of cases -Clinical signs and symptoms appear 1 to 3 days *** If the diver then ascends (depressurizes) after injury. too rapidly, the nitrogen bubbles comes out of Sudden onset of solution in the blood to form gas emboli that can 1- Tachypnea. (abnormally rapid breathing rate) induce focal ischemia in a number of tissues, 2- Dyspnea.(Difficulty in breathing ) including brain and heart. 3-Tachycardia. 4- Irritability, and restlessness, 5-Can progress rapidly to delirium(‫)تشويش بالتفكير‬ The rapid formation of gas bubbles within or coma. skeletal muscles and supporting tissues in and about joints is responsible for the painful condition called the bends Air Embolism In the lungs, gas bubbles in the vasculature ~Gas bubbles within the circulation cause edema, hemorrhages, leading to can coalesce and obstruct vascular respiratory distress, called the chokes. flow and cause distal ischemic injury. - Treating acute decompression sickness requires placing the affected individual in a compression chamber to increase barometric pressure and force the gas bubbles back into solution. Infarction -Ischemic necrosis caused by occlusion of the vascular supply to the affected tissue. Examples: - Myocardial or cerebral infarction. - Pulmonary infarction - Bowel infarction - Ischemic necrosis of distal extremities (gangrene) esp. in the diabetics. -White infarcts occur with : Causes of infarction - Arterial occlusions in solid organs with end- -Arterial thrombosis or arterial embolism arterial circulations (e.g., heart, spleen, and kidney) underlies the vast majority of infarctions. - ischemic coagulative necrosis. - in the central nervous system results in liquefactive necrosis *Less common causes* - Most infarcts are replaced by scar. 1-Vasospasm. (Spasm of coronary artery) 2-Expansion of an atheroma (bleeding in to an atheromatous plaque) 3-Extrinsic compression of a vessel, by tumor. 4- Venous thrombosis thus usually occur only in organs with a single efferent vein (e.g. testis or ovary). Types of infarcts - Infarcts may be either red (hemorrhagic) or white (anemic). Red infarcts occur in: (1) with venous occlusions (such as in ovarian torsion); (2) in loose tissues (e.g., lung) (3) in tissues with dual circulations such as lung and small intestine,; (4) in previously congested tissues (as a consequence of sluggish venous outflow). (5) when flow is reestablished after infarction  Shock -Is characterized by systemic hypoperfusion of tissues. It can be caused by : 1. diminished cardiac output. 2. reduced effective circulating blood volume - Consequences are impaired tissue perfusion and cellular hypoxia (organ failure) Forms of shock -results from low cardiac output due to myocardial pump failure. Cardiogenic shock - It may be caused by myocardial damage (infarction), ventricular arrhythmias, extrinsic compression (cardiac tamponade), or outflow obstruction (e.g., pulmonary embolism). results from low cardiac output due to loss of blood or Hypovolemic shock plasma volume (e.g., due to hemorrhage or fluid loss from severe burns). Septic shock -results from arterial vasodilation and venous blood pooling that stems from the systemic immune response to microbial infection. gram-positive bacteria constitute the most common cause of septic shock