Blood vessel trauma

When the extent of the trauma to the vessel is increased, the degree of vascular constriction is increased. Accordingly, a sharply cut blood vessel bleeds far more profusely than a blood vessel damaged by a more crushing injury. The vasoconstriction may last for many minutes or hours, thus... 

Hemorrhagic strokes account for 12% of strokes and include subarachnoid hemorrhage, intracerebral hemorrhage, and subdural hematomas. Subarachnoid hemorrhage may result from trauma or rupture of an intracranial aneurysm or arteriovenous malformation. Intracerebral hemorrhage occurs when a ruptured blood vessel within the brain parenchyma causes formation of a hematoma. Subdural hematomas are most often caused by trauma. 

The term shock when used in medicine relates to an acute state of general weakness and the restriction of many vital functions. Patients in shock are generally apathetic, their face is sunken and their expression is full of anxiety skin is moist, cold and gray, pulse is rapid and faint, blood pressure is normally low, musculature is lax and superficial blood vessels are empty respiration is superficial, basal metabolism is reduced and urine formation is considerably slower. Shock may be triggered by a variety of causes severe physical injury with excessive loss of blood, surgery or severe psychic trauma in predisposed persons it may also arise as a reaction to exogenous substances such as antibiotics or bee poison. 

Administration of succinylcholine may be associated with the rapid onset of an increase in intraocular pressure (< 60 seconds), peaking at 2-4 minutes, and declining after 5 minutes. The mechanism may involve tonic contraction of myofibrils or transient dilation of ocular choroidal blood vessels. Despite the increase in intraocular pressure, the use of succinylcholine for ophthalmologic operations is not contraindicated unless the anterior chamber is open ("open globe") due to trauma. 

Kolf s early devices were used for patients who had suffered acute kidney failure as a result of trauma or poisoning and needed dialysis only a few times. Such emergency treatment was the main application of hemodialysis until the early 1960s, because patients suffering from chronic kidney disease require dialysis two to three times per week for several years, which was not practical with these early devices. However, application of hemodialysis to this class of patient was made possible by improvements in the dialyzer design in the 1960s. The development of a plastic shunt that could be permanently fitted to the patient to allow easy access to their blood supply was also important. This shunt, developed by Scribner et al. [6], allowed dialysis without the need for surgery to connect the patient s blood vessels to the dialysis machine for each treatment. 

Q6 A thrombus is a blood clot which is fixed to the blood vessel wall. When it detaches and is carried in the blood, it is known as an embolus. Both thrombi and emboli can block blood vessels and deprive tissues of oxygen. In arteries blood clots usually form because the inner surface has been altered by deposition of atheroma. In contrast venous thrombosis results from slow or stagnant blood flow in veins, or defects in mechanisms which normally oppose inappropriate coagulation. Three major risk factors for pulmonary embolism are (i) venous stasis, (ii) hypercoagulability ofblood and (iii) injury to vascular endothelium following trauma or plaque rupture. 

Intranasal use, a common method of cocaine abuse, can damage the sinonasal tract, causing acute and chronic inflammation, necrosis, and osteocartilaginous erosion (SEDA-17, 36). These conditions occur secondary to the combined effects of direct trauma from instrumentation, vasoconstriction of small blood vessels with resultant ischemic necrosis, and chemical irritation from adulterants. Intranasal cocaine users can develop septal perforation, saddle-nose deformities, and sinonasal structural damage. 

Vascular spasm. In which the blood vessels contract as a result of neurological reflexes and local myogenic (muscle) spasm. The degree of constriction is directly proportional to the degree of trauma. The spasm may last up to 30 minutes. 

Figure 10.37. Blood-Clotting Cascade. A fibrin clot is formed by the interplay of the intrinsic, extrinsic, and final common pathways. The intrinsic pathway begins with the activation of factor XII (Hageman factor) by contact with abnormal surfaces produced by injury. The extrinsic pathway is triggered by trauma, which activates factor VII and releases a lipoprotein, called tissue factor, from blood vessels. Inactive forms of clotting factors are shown in red their activated counterparts (indicated by the subscript "a") are in yellow. Stimulatory proteins that are not themselves enzymes are shovm in blue. A striking feature of this process is that the activated form of one clotting factor catalyzes the activation of the next factor.

The meninges are three separate membranes, layered together, which serve to encase the brain and spinal cord. The dura is the toughest, outermost layer, and is closely attached to the inside of the skull. The middle layer, the arachnoid, is important in the normal flow of the cerebrospinal fluid (CSF), a lubricating fluid which bathes both the brain and the spinal cord. The innermost layer, the pia, helps direct brain blood vessels into the brain. The space between the arachnoid and the pia contains CSF, which serves to help insulate the brain from trauma. Through this space course many blood vessels. 

If acupuncture, which entails tissue trauma, is performed properly and on the correct acupuncture points, trauma will affect only the skin and the connective tissue below. If, however, acupuncture needles are inserted at the wrong site or penetrate too deeply, other tissues or organs can be affected. Traumatic complications of acupuncture have been reviewed (108). They have been described in relation to the thoracic and abdominal viscera, in the peripheral and central nervous systems, and in blood vessels. Several deaths have been reported from pneumothorax and cardiac tamponade. The anatomical tissues at several acupuncture points are such that needles can injure vulnerable structures. Thus, good knowledge of anatomy is an essential precondition for acupuncturists. 

The extrinsic pathway is mediated by tissue factor (TF), also known as thromboplastin or factor HI (Fig. 11.6a). Tissue factor is not present in blood plasma, i.e., it is extrinsic or outside of the vascular system. TF is a membrane protein that becomes exposed to the blood by trauma to the endothelial surface of blood vessels. It is especially rich in the membranes of pericytes, platelets, and leukocytes, but present in lesser amounts in most cells. It is absent from striated muscle cells and chondroblasts. 

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