Distributive shock
Distributive shock |
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Distributive shock is a
Types
Elbers and Ince have identified five classes of abnormal microcirculatory flow in distributive shock using side stream
- Class I: all capillaries are stagnant when there is normal or sluggish venular flow.
- Class II: there are empty capillaries next to capillaries that have flowing red blood cells.
- Class III: there are stagnant capillaries next to capillaries with normal blood flow.
- Class IV: hyperdynamic flow in capillaries adjacent to capillaries that are stagnant.
- Class V: widespread hyperdynamic flow in the microcirculatory system.[2]
According to the cause, there are 4 types of distributive shock:
- Neurogenic shock: Decreased sympathetic stimulation leading to decreased vessel tone.
- Anaphylactic shock
- Septic shock
- Shock due to adrenal crisis
Causes
In addition to sepsis, distributive shock can be caused by
Pathophysiology
The cause of inadequate tissue perfusion (blood delivery to tissues) in distributive shock is a lack of normal responsiveness of blood vessels to vasoconstrictive agents and direct vasodilation.[4]
There are four types of distributive shock. The most common,
In anaphylactic shock low blood pressure is related to decreased systemic vascular resistance (SVR) triggered primarily by a massive release of histamine by mast cells activated by antigen-bound immunoglobulin E and also by increased production and release of prostaglandins.[4]
Neurogenic shock is caused by the loss of vascular tone normally supported by the sympathetic nervous system due to injury to the central nervous system especially spinal cord injury.[4][6] Rupture of a hollow organ, with subsequent evacuation of contents in the peritoneal cavity could also determine neurogenic shock, a subtype of distributive shock. This happens due to the widespread peritoneal irritation by the ruptured viscus contents, as in peptic ulcer perforation, with consequent strong vagal activation, and generalized, extensive peripheral vasodilation and bradycardia.[7][8] Thus, in neurogenic shock, there is decreased systemic vascular resistance, CVP is typically decreased, CO decreased or normal, and PAOP decreased.[2]
Distributive shock associated with adrenal crisis results from inadequate steroid hormones.
Diagnosis
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Treatment
The main goals of treatment in distributive shock are to reverse the underlying cause and achieve
People with septic shock are treated with
Anaphylactic shock is treated with
Prognosis
Septic shock is associated with significant mortality and is the leading non-cardiac cause of death in intensive care units (ICUs).[1]
Research directions
The choice of fluids for resuscitation remains an area of research, the Surviving Sepsis Campaign an international consortium of experts, did not find adequate evidence to support the superiority crystalloid fluids versus colloid fluids.[10] Drugs such as, pyridoxalated hemoglobin polyoxyethylene, which scavenge nitric oxide from the blood have been investigated.[16] As well as methylene blue which may inhibit the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway which has been suggested to play a significant role in distributive shock.[17]
References
- ^ a b c Kanaparthi, Lalit K.; Klaus-Dieter, Lessnau; Peralta, Ruben (12 February 2013), Pinsky, Michael R. (ed.), "Distributive Shock: Overview: Background", Medscape Reference, Medscape, retrieved 2014-04-28.
- ^ PMID 16879732.
- ^ a b c d e Kanaparthi et al. 2013, Overview: Etiology.
- ^ a b c d e f Kanaparthi et al. 2013, Overview: Pathophysiology.
- ^ PMID 16168069.
- PMID 23098715.
- S2CID 1458157.)
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: CS1 maint: multiple names: authors list (link - ^ Civetta, Taylor, & Kirby's Critical Care, 4th Edition. Chapter 59 Neurogenic Shock. Lippincott Williams & Wilkins 2009
- ^ Kanaparthi et al. 2013, Treatment: Approach Considerations.
- ^ a b Kanaparthi et al. 2013, Treatment: Resuscitation.
- ^ Kanaparthi et al. 2013, Treatment: Corticosteroids.
- ^ Kanaparthi et al. 2013, Treatment: Antimicrobial Treatment.
- ^ Kanaparthi et al. 2013, Treatment: Surgical Control of Shock Sources.
- ^ Kanaparthi et al. 2013, Treatment: Treatment of Anaphylaxis.
- PMID 29801010.
- S2CID 30123186.
- PMID 23580172.