1
4th stage
Medicine
Lec-17
د.جاسم
1/3/2016
SHOCK
Shock :- is a syndrome of impaired tissue oxygenation and perfusion which fails
to meet the metabolic requirement due to a variety of etiologies.
Pathophysiology :-
1-Cells switch from aerobic to anaerobic metabolism
2-lactic acid production
3-Cell function ceases & swells
4-membrane becomes more permeable
5-electrolytes & fluids seep in & out of cell
6-Na+/K+ pump impaired
7-mitochondria damage
8-cell death
COMPENSATORY MECHANISMS:
1- Sympathetic Nervous System (SNS)-Adrenal Response
2- SNS - Neurohormonal response Stimulated by baroreceptors
1. Increased heart rate
2. Increased contractility
3. Vasoconstriction (Afterload)
4. Increased Preload
3- Hormonal: Renin-angiotension system
Releases renin angiotension II
angiotension I
Decrease renal perfusion
potent vasoconstriction & releases aldosterone adrenal cortex sodium &
water retention ( intravascular volume )
2
4-Antidiuretic Hormone
Osmoreceptors in hypothalamus stimulatedADH released by Posterior
pituitary gland Vasopressor effect to increase BP
-Acts on renal tubules to retain water
Stages of Shock :-
❇ Initial stage - tissues are under perfused
❇Compensatory stage - Reversible.
❇Progressive stage - Failing compensatory mechanisms , Decompensated.
❇Irreversible or refractory stage - Cellular necrosis and Multiple Organ
Dysfunction Syndrome may occur
DEATH IS IMMINENT!!!!
Clinical Presentation: Generalized Shock
Vital signs :-
- Hypotensive: (may be WNL or due to compensatory mechanism)
< 90 mmHg
- MAP < 60 mmHg
- Tachycardia: Weak and Thready pulse
- Tachypneic : blow off CO2 , Respiratory alkalosis
- Mental status: (LOC) restless, irritable, apprehensive and unresponsive
- Decreased Urine output
Shock Syndromes(Types) :-
1-Hypovolemic Shock
blood VOLUME problem
2-Cardiogenic Shock
blood PUMP problem
3-Distributive Shock [septic ; anaphylactic ; neurogenic]
blood VESSEL problem
3
Hypovolemic shock
Loss of circulating volume decrease tissue perfusion
Etiology :
1- External fluid or blood loss.
1-Fluid loss: Dehydration Nausea & vomiting, diarrhea, massive diuresis,
extensive burns
2-Blood loss: trauma: blunt and penetrating
BLOOD YOU SEE
BLOOD YOU DON’T SEE
2- Internal fluid loss
-pancreatitis
Clinical Presentation :
Tachycardia and tachypnea
Weak, thready pulses
Hypotension
Skin cool & clammy
Mental status changes
Decreased urine output: dark & concentrated
Assessment & Management :
S/S vary depending on severity of fluid loss:
15%[750ml]- compensatory mechanism maintains CO
15-30% [750-1500ml- Hypoxemia, decreased BP & UOP
30-40% [1500-2000ml] -Impaired compensation & profound shock
along with severe acidosis
40-50% - refactory stage
loss of volume= death
4
Initial Management Hypovolemic Shock
Early Recognition- Do not relay on BP! (30% fld loss)
Control hemorrhage
Restore circulating volume crystalloids(NS),colloids(dextran)
Optimize oxygen delivery
Vasoconstrictor if BP still low after volume loading
Cardiogenic shock
The impaired ability of the heart to pump blood
Pump failure of the right or left ventricle
Mortality rate of 80 % or MORE
Etiology:
Most common cause is LV MI (Anterior) ,Occurs when > 40% of ventricular
mass damage
mechanical complications of MI:
- Papillary Muscle Rupture
- Ventricular aneurysm
- Ventricular septal rupture
Other causes:
- Cardiomyopathies
- Tamponade
- Arrhythmias
- valve disease
Pathophysiology
Impaired pumping ability of LV leads to
- Decreased stroke volume leads to…..
- Decreased CO leads to …..
- Decreased BP leads to…..
5
- Compensatory mechanism which may lead to
- Decreased tissue perfusion !!!!
- Inadequate systolic emptying leads to ...
- Left ventricular filling pressures (preload) leads to...
- Left atrial pressures leads to ….
- Pulmonary capillary pressure leads to …
- Pulmonary interstitial & intraalveolar edema !!!!
Clinical Presentation :
Features of shock (Hypotension + Hypoperfusion) with features of pulmonary
congestion.
Features of cause VSD , Tamponade
MANAGEMENT :
Goals of management :
- Treat Reversible Causes
- The main goal is to improve myocardial function
- Arrhythmia should be treated
- Reperfusion PCI is the treatment of choice in ACS
- Inotropes and vasopressor Dobutamine,Dopamine
- Intra-aortic balloon pump
- Cautious administration of fluid
- Pulmonary artery monitoring is a necessity
Steps :
- Morphine as needed (Decreases preload, anxiety)
- Cautious use of diuretics in CHF
- Vasodilators as needed for afterload reduction
- Short acting beta blocker, for refractory tachycardia
6
Distributive shock
Inadequate perfusion of tissues through maldistribution of blood flow and
volume because of alterations in blood vessels
Cardiac pump & blood volume are normal but blood is not reaching the tissues
Etiology
- Septic Shock (Most Common)
- Anaphylactic Shock
- Neurogenic Shock
Anaphylactic Shock
A type of distributive shock that results from widespread systemic allergic
reaction to an antigen
This hypersensitive reaction is LIFE THREATENING
Etiology
- Antigen exposure
- body stimulated to produce IgE antibodies specific to antigen
drugs, bites, contrast, blood, foods, vaccines
- Reexposure to antigen
IgE binds to mast cells and basophils
- Anaphylactic response
Clinical Presentation
- Almost immediate response to inciting antigen
- Cutaneous manifestations
urticaria, erythema, pruritis, angioedema
- Respiratory compromise
stridor, wheezing, bronchorrhea, resp. distress
- Circulatory collapse
tachycardia, vasodilation, hypotension
7
Management
- Early Recognition, treat aggressively
- AIRWAY SUPPORT
- IM EPINEPHRINE
- Antihistamines
- Corticosteroids
- IMMEDIATE WITHDRAWAL OF ANTIGEN IF POSSIBLE
- Judicious crystalloid administration
Neurogenic shock
Most common etiology: Spinal cord injury above T6
Causes massive vasodilatation in the venous vasculature, venous return to
heart, cardiac output.
Neurogenic is the rarest form of shock!
Assessment , Diagnosis and Management of Neurogenic Shock
~ PATIENT ASSESSMENT
- Hypotension
- Bradycardia
- Hypothermia
- Warm, dry skin
- CO
- Flaccid paralysis below level of the spinal lesion
~
MEDICAL MANAGEMENT
- Goals of Therapy are to treat or remove the cause
- Treat Hypovolemia ,hypothermia , hypoxia.
- Vasopressors may be needed.
- DVT prophylaxsis.
8
-
Sepsis
Systemic Inflammatory Response (SIRS) to INFECTION manifested by
two or > of following:
- Temp > 38 or < 36 centigrade
- HR > 90
- RR > 20 or PaCO2 < 32
- WBC > 12,000/cu mm or < 4,000
Septic shock :-
Sepsis with Hypotension (SBP < 90 or > 40 reduction from baseline) despite
adequate fluid resuscitation
Risk Factors Associated with Septic Shock
1- Age
2- Malnutrition
3- General debilitation
4- Use of invasive catheters
5- Traumatic wounds
6- Drug Therapy
Pathophysiology :
Initiated by gram-negative (most common) or gram positive bacteria, fungi or
viruses
Cell walls of organisms contain Endotoxins
Endotoxins release inflammatory mediators (systemic inflammatory response)
causes…...
Vasodilation & increase capillary permeability leads to
Shock due to alteration in peripheral circulation & massive dilation
9
Clinical Presentation :
Two phases:
a. “Warm” shock - early phase
i. hyperdynamic response, VASODILATION
b. “Cold” shock - late phase
i. hypodynamic response
Clinical Manifestations :
Early --- hyperdynamic state --- compensation
- Pink, warm, flushed skin
- Increased Heart Rate
- Tachypnea
- Massive vasodilation
- Increased CO
- Crackles
Late -- hypodynamic state -- decompansation:
- Vasoconistriction
- Skin is pale & cold
- Tachycardia
- Decrease BP
- Change LOC
- Decrease UOP
- Decrease CO
- Metabolic & respiratory acidosis with hypoxemia
11
Management :
- Prevention !!!
- Find and kill the source of the infection Antimicrobial
- Fluid Resuscitation
- Vasoconstrictors
- Inotropic drugs
- Maximize O2 delivery Support
- Nutritional Support
- Comfort & Emotional support
SH.J