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Shock

الكلية كلية طب حمورابي     القسم الكلية ذات القسم الواحد     المرحلة 2
أستاذ المادة شهلاء خزعل عبد محمد جابك       14/11/2016 06:59:32
Shock is a clinical syndrome of circulatory failure characterized by:
• Low cardiac output.
• Hypotension.
• inadequate tissueperfusion
Causesand types:
Shock occurs as a result of many disorders, and according to the underlying cause, four main types ofshock can beidentified.
1-Hypovolsemic shock
This occurs as a result of severe reduction of the blood volume. Its manifestations are those of severe haemontage It is called cold shock because the skin of the patient is cold due to severe cutaneous vasoconstriction.
Causes and types:
1. Hemorrhagic shock (severe haernorrhage)
2. Traumatic shock (severe trauma): This may be complicated by precp1tation of myoglobin (from the crushed muscles) in the renal tubules resulting in renal shutdown, kidney damage and anuria (crush syndrome)
3. Burn shock (extensive bums): It is a hypovolemic shock which follow extensive burns it is mainly due to loss of large amounts of plasma from the burned areas.
4. Surgical shock (major surgery): It is a hypovolemic shock which follows surgical operation (it is due to external and or internal hemorrhage)
5. Dehydration (e g in severe diarrhea) it is due to lass of large amount ofNa+ in the urine or feces with the loss of water leading again to hypovolemic shock.

2-flistribntfre shock
This type of shock is caused by widespread vasodilation (VD) which markedly increases the capacity of the vascular system. The blood volume is normal but the cardiac output is maldistributed to different organs where more blood goes to the inactive abdominal viscera, skeletal muscles and skin and less bloodgoes to the active, vital organs especially the heart and brain which become under-perfused its manifestations are generally similar to those of hypovolemic shock, but the skin is warm due to VD (hence the name warm shock). Examples:
Neurogenic shock
This is a distributive shock which occurs on receiving sudden, shocking news strong emotions as extreme fear, grief or se ere pan in these cases, shocking news may cause failure of the sympathetic tone i e there is sudden withdrawal of the sympathetic vasomotor tone which results in widespread vasodilation. The decrease in cerebral blood flow leads to fainting (a= a prolonged syncope loss of consciousness due to cerebral ischemia).
A rapid fall in the blood pressure (B.P) also occurs in neurogenic shockin which the sympathetic tone is decreased,usually because of upper spinal card damage or spinal anesthesia.
Anaphylactic shock:
This is a distributive shock caused by a severe allergic reaction to an antigen to which the subject was previously exposed, and sensitized, eg. an injection of penicillin. The resulting antigen-antibody reaction causes the release of large amounts of histamine which produces massive vasodilation.
Septic shock:
This is a distributive shock produced by the invasion of the blood stream by bacteria or their toxins; especially the gram-negative bacteria which release an endotoxin that stimulates the polymorph nuclear leucocytes and tissue macrophages to secrete many VD cytokines (especially interleukin-i. tumor necrosis factor (TNT)). These substances produce massive vasodilation leading to shock.
3-Cardiogenic shock (Congested shock)


المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .