Patho & Pathophis Shock 2 Flashcards by William Mills

What is Distributive shock characherised as

Loss of vessel tone
Enlarged vascular compartment
Displaced vascular volume from heart/central circulation

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What are the 2 main causes of distributive shock

Decreased sympathetic control
Excessive vasodilatory substances released

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How is Distributive shock described

Blood volume stays the SAME. Vasculature expands until normal volume doesn’t fill circulatory system

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What happen in Distributive shock

In distributive shock the vessels stay in vasodilation causing more plasma to leak out of the vessel into the interstitial space, therefore leading to decreased blood volume

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What are the 3 subsets of Distributive shock

Neurogenic
Anaphylactic
Septic

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What causes Neurogenic shock

Parasympathetic overstimulation and sympathetic under stimulation

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What can cause neurogenic shock

Injury to spinal cord or medulla
Hypoxia
Lack of glucose to CNS
CNS depressing drugs
General anaesthesia

In addition to loss of autonomic processes there is also a loss of thermoregulation due to the inability to sweat

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What is the progression of Neurogenic shock

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What defines anaphylaxis

Anaphylaxis is severe, life threating, systemic hypersensitivity reaction resulting in decreased blood pressure, airway obstruction and severe hypoxia

Mostly caused by a type 1 hypersensitivity

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What are some common causes of anaphylaxis

Foods
Insect venom
Latex
Meds
Immunotherapy

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Define an Antigen

Something that stimulates an immune response

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Define an Allergen

An antigen that causes an allergy

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Define Hypersensitivity

Abnormal & excessive response of activated immune system causing injury & damage to host tissues

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Define an Allergy

A type 1 hypersensitivity reaction

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Define an Antibody

A family of defensive proteins the body makes when stimulated by an antigen. These are produces by B lymphocytes and plasma B cells

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Immune response

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What are hypersensitivity Disorders

Collective term for immune response disorders

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What is a type 1 Hypersensitivity disorder

Classic allergic response IgE-mediated.
They develop rapidly on exposure to antigen

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Sensation stage of initial allergen exposure

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What are essential in producing type 1 hypersensitivity reactions

Mast cells & Basophils

Anaphylactic reaction subsequent exposure

What happen in mast cell degranulation

As the antibodies attach to the mast cell they release a bunch of different mediators which have a inflammatory response

What is the action of Histamine

This causes an increase in nitric oxide production which is a strong vasodilator it also causes smooth muscle in the bronchioles to constrict, while causing vascular smooth muscle to relax. This increases permeability of the vessels resulting in more oedema in the pulmonary system and reduced preload to the heart affecting MAP

How many distinct phases does anaphylactics have

2
A primary - which commences 5-30 mins post allergen exposure & subsides within 60mins. This is mediated by the key mediator HISTAMINE

In the primary stage it causes vasodilation, vascular leakage, smooth muscle contraction (in the broncus)

The secondary phase typically occurs 2-8 hrs after resolution can last several days.
The main cause are eosinophils (type of white blood cell) residing in connective tissue underneath respiratory, gut, urogenital epithelium
It releases toxic proteins & free radicals
It causes intense infiltration of tissues with eosinophils & other acute chronic inflammatory cells & tissue destruction

What are Atopic Reactions

Local hypersensitivity reactions usually occur when offending allergen is confined to particular exposure site. People prone to atopy often develop reactions to more than one environmental allergen causing yearly symptoms. Some symptoms are Urticarial -skin rash Allergic rhinitis - inflammation and irritation of mucus in the nose Atopic dermatitis - eczema Bronchial asthma

What is Atopy

Atopy is the predisposition for people to develop allergic reactions when coming into contact with an allergen. People are more likely to have Atopy when there is a family history

Summary of Anaphylaxis

What is sepsis

It is a systemic reaction to a pathogen

What are the first 2 steps of sepsis

The pathogen attaches to the toll-like receptors on white blood cells. From this it causes the activation of plasma derived inflammatory mediators and cell derived inflammatory mediators

What is included in the plasma derived inflammatory mediators

The complement system Coagulation factors The kinin system

What is included in the complement system

This includes a number of proteins that induce vascular permeability and vasodilation. This results in heat and redness, it also causes antigens and antibodies to bind for the immune response

What is included in the coagulation factors

These are plasma proteins, in particular thrombin stimulates realse of CELL derived mediators for the cascade of inflammation to continue, Causes inappropriate clotting

What is included in the Kinin system

This is part of the plasma protein family leading to the activation of the inflammatory response including vasodilation, blood coagulation & pain

What is included in the cell derived inflammatory mediators

Histamine Proinflammatory cytokines Leukocytes Prostoglandins

Where is Histamine produced

It is produced in the basophils and mast cells, it increases permeability so fluid leaks out into surrounding tissue

What are Proinflammatory cytokines

These are cell signaling proteins. Their net effects are fever, vasodilation, hypotension, oedema, elevated white blood count

What is the role of Leukocytes (white blood cells)

These adhere to adhesion cells and leave the circulatory system to extravascular tissue

What do Prostaglandins do

This cause inflammation, can trigger clotting cascade and innate organ failure

What are some symptoms that patients may be complaining of in sepsis

Sore limbs Headache low Temp

What are the late stages of sepsis

Depressed myocardial function Leucopoenic - Thrombocytopenia - Thrombi Pulmonary congestion DIC - Disseminated intravascular coagulation

What triggers depressed myocardial function

You eventually become acidotic which leads to cellular oedema therefore causing less venus return to the heart and less cardiac output. The pathogen is also toxic to cardiac cells

What is Leucopoenia

This is the bodies ability to make new white blood cells. Becuase the body has been fighting the infection for so long it can not longer make as many

What does thrombi mean

Thrombi is the wide spreading clotting factors that is going on in the body

What causes pulmonary congestion

Pulmonary congestion is caused by the wide spread clotting factors occurring in the body, the pulmonary tissue is especially susceptible to inflammation and impairment

What is DIC

Disseminated intravascular coagulation. This is wide spread coagulation that can cause damage to the microvasculature which can cause organ dysfunction. This is also where strong anticoagulants are released therefore increasing bleeding

What is a indication of DIC

Bruising on their skin (blotches all over the skin) This is because of the increased bleeding going on

What are some signs of MODS

Multiple organ dysfunction is serve pulmonary impairment with fluid building up in the lungs making gas exchange non effective. another sign is VT or VF because of the heart being affected

Summary of sepsis

Is temperature a guide to sepsis?

No high temp is the FIRST response on the infection. Dont use it as a hallmark for diagnosis