Types And Mechanisms of Shock | Dr Najeeb Lecture

Types And Mechanisms of Shock | Dr Najeeb Lecture
In This short tutorial IHAVE explained the concepts in understanding shock and the pathogenesis of septic shock.
Medical Shock is defined as a decrease in blood pressure. There are many types of shock. This video focuses on Cardiogenic shock, which means shock caused by something wrong with the heart.
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Types, Mechanisms & Stages of Shock

(0:00-22:20)
Definitions of different types of shocks;
HYPOVOLEMIC SHOCK
CARDIOGENIC SHOCK
DISTRIBUTIVE SHOCK & its 3 types:
1-Anaphylactic Shock
2-Neurogenic Shock
3-Septic Shock
OBSTRUCTIVE SHOCK

(22:22-36:18)
CAUSES of HYPOVOLEMIC SHOCK
1-HEMORRHAGE:
External Hemorrhage
Internal Hemorrhage

2-LOSS OF PLASMA:
Exfoliative Dermatitis

3-LOSS OF FLUIDS & ELECTROLYTES:
Diarrhea & Vomiting
Polyuria: e.g., Diabetic Ketoacidosis
Excessive Sweating
3rd Spacing; Ascites, Bowel Obstruction, Acute Pancreatitis,

(36:20-53:08)
CARDIOGENIC SHOCK
1-ARRHYTHMIAS:
Tachyarrhythmia & Bradyarrhythmia
2-TRUE PUMP FAILURE:
Massive Myocardial Infarction
Cardiomyopathies
CARDIOMYOPATHIES
3-SEVERE VALVULAR DYSFUNCTION:
Valvular Regurgitation; like Mitral Valve Regurgitation, Aortic Valve Regurgitation.
4-RUPTURE OF VENTRICULAR SEPTUM or FREE WALL

(53:09-1:02:34)
DISTRIBUTIVE SHOCK:
1-Neurogenic Shock:
Vasomotor Center Failure/Depression
2-Anaphylactic Shock
3-Septic Shock
4-Acute Adrenal Insufficiency

(1:02:35-1:15:18)
OBSTRUCTIVE SHOCK:
1-Cardiac Tamponade
2-Tension Pneumothorax
3-Massive Pulmonary Embolism
4-Atrial Myxoma
5-Left Atrial Mural Thrombus
Syncope; Vasovagal shock.

(1:15:20-1:21:20)
Outline of STAGES OF SHOCK:
1-Non-Progressive Compensated Stage
2-Progressive Stage of Shock
3-Refractory Shock/Irreversible Shock


(1:21:21-1:52:05)
NON-PROGRESSIVE COMPENSATED STAGE SHOCK; in detail:
1-Sympathetic Autonomous Nervous System (SANS):
Chemoreceptors, Baroreceptors, Vasomotor Center, Vasoconstriction & Arterioloconstriction
Cardiac Output (CO) & Systolic Blood Pressure (SBP), Total Peripheral Resistance (TPR) & Diastolic Blood Pressure (DBP)
Compensatory mechanisms try to stabilize the blood pressure.

2-Renin-Angiotensin-Aldosterone Axis System (RAAA):
Reduced renal perfusion, Renin release, Angiotensin-1, Angiotensinogen (ATG), Angiotensin-2 (AT-2)
Why more Renin is released?
Arterioloconstriction leads to increased TPR; DBP stabilized.
AT-2 act on Adrenal Cortex; ZG will release Aldosterone; salt & water retained; increased blood volume;
SBP stabilized.

3-ADH(Vasopressin)

4-REVERSE STRESS-RELAXATION of Circulatory System
5-FLUID SHIFT (Interstitial to Vascular)

(1:52:07-2:06:44)
PROGRESSIVE STAGE OF SHOCK:
Compensatory Mechanisms are exhausted and are failing; deterioration starts.
Fight b/w Vasoconstrictor & Vasodilator mechanisms.
"Peripheral tissues will become resistant to the compensatory vasoconstrictor mechanisms & start vasodilating".
Endothelial Cells are injured; NO released which acts as Vasodilator and cardio depressant.
Lactic Acidosis
Disseminated Intravascular Coagulation (DIC)

(2:06:45-2:16:34)
REFRACTORY IRREVERSIBLE STAGE:
"Cells & tissues start committing suicide".
1-Na+K+ ATPases are not working
2-Lysosomal Membrane breaks down
3-ATP into Adenosine; raised uric acid in blood
Post mortem findings in these patients.

(2:16:36-2:36:00)
SEPTIC SHOCK & its types:
1-Bacteremia
2-Septicemia
3-Endotoxemia
Differences b/w in Gram +ve & Gram -ve bacteria.
Differences b/w Endotoxins & Exotoxins.
4-Pyemia
5-Empyema
6-Abscess

(2:36:04-3:07:40)
SEPTIC SHOCK continued:
How LPS work? Working of Endotoxins.
CD-14 receptor on endothelial cell; Toll-like receptors; Cytokines release; clinical features of shock.
Also called "warm shock".
Effect of Low Concentration of Cytokines, Moderate Concentration of Cytokines & High Concentration of Cytokines.
Multi Organ Failure (MOF).
Some Gram +ve & Fungi can produce septic shock like exotoxins.
Super Antigen; Toxic Shock Syndrome Toxin; Staphylococci.
Laboratory Investigations.

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