Shock Definition

• Circulatory shock is a clinical syndrome characterized by

inadequate tissue perfusion (hypoperfusion) of oxygen
and other nutrients, resulting in first reversible and then,
if prolonged, irreversible cellular injury.

• The resulting deficit in tissue oxygenation leads to

cellular hypoxia and anaerobic metabolism manifested
systemically as lactic acidosis.

• If not interrupted, the cascade of cell death, end-organ

damage, and multisystem organ dysfunction can cause
significant morbidity and death.
 Definitions
Item Definition Formula Measurment Average
Blood pressure (BP) The force that the heart use to pumb blood around CO X SVR Invasive = cardiac 120/80
the body. catheter
Systolic = pressure during cardiac contraction systemic vascular

Diastolic = pressure during cardiac rest

resistance
Non-invasive=
sphegmomanometer
Cardiac output (CO) The amount of blood pumped by the heart HR X SV Thermodilution catheter 5-6L/min at
throughout the circulatory system in a minute. stroke volume rest
>35L/min in
athelets
Systemic vascular Also known as total peripheral resistance (TPR), is [MAP-CVP] X Ultrasound measurement, 700-15000
resistnace (SVR) the amount of force exerted on circulating blood by 80/CO or invasive measurement dynes/sec/cm
-5
the vasculature of the body. Three factors determine
the force: the length of the blood vessels in the body, mean arterial pressure
the diameter of the vessels, and the viscosity of the central venous pressure
blood within them.
Definitions

Item Definition Formula Measurment Average

Mean arterial The average arterial pressure throughout DP + 1/3 Calculated from the 70-100
pressure(MAP) one cardiac cycle, systole, and diastole. (SP-DP) formula

Under normal circumstances, 85%

of the circulating blood volume is
housed in the venous capacitance
vessels.
Pathophysiology of Shock

• In ICU patients with arterial lactate levels > 10

>10 mm/dl mm\dl the mortality rates are around 80%

• In ICU patients with arterial lactate levels around

5 mm/dl 5 mm\dl the mortality rates are around 50%

• In ICU patients with arterial lactate levels < 2

<2 mm/dl mm\dl the mortality rates are around 20%
Pathophysiology of Shock

Traditionally
hypotension is the
hallmark of
circulatory shock —
Therefore monitoring
blood pressure is
essential for critically
ill patients
Pathophysiology of shock

sphygmomanometer

Non-invasive

Measurement of
blood pressure

Invasive
cardiac catheter
Pathophysiology of Shock

Sometimes, patients may have

hypoperfusion; however, they
are normotensive (due to
compensatory mechanism)
Hypoperfusion
Occasionally, a patient may be
hypotensive but not in a shock
(due to vasodilatation with
Hypotension —> Hypo-perfusion —> Shock
normal intravascular volume
and cardiac output and
maintained tissue perfusion)
Pathophysiology of Shock

Hemorrhage Decrease blood volume Decrease SV

Increase HR (to
Decrease CO Further bleeding maintain CO & BP
normal)

Accordingly, patients may have normal or

Increase SVP (to maintain BP) even elevated blood pressure in the face of
substantial systemic hypoperfusion (cryptic
shock).
Pathophysiology of Shock

Shock is best
conceptualized as an
imbalance between tissue
oxygen supply and tissue
oxygen demand
Pathophysiology of Shock

Oxygen delivery = PaO2

(must be maintained at a
minimum of 80-85 mmHg
to keep Hemoglobin
nearly saturated by
oxygen) X Cardiac Output
Classification of Shock

Hypovolemic Obstructive Disributive Cardiogenic

shock shock shock shock

Four organ systems

Blood & fluid Vascular Circulatory

Heart
compartment system system
Hypovolemic Shock
Hypovolemic Shock

Definition: It is a condition of inadequate tissue perfusion caused by loss of intravascular

volume (usually acute). Subsequently, there will be a critical drop in cardiac preload and
reduced micro- & macro-circulation.

Subtypes
Hemorrhagic shock Traumatic hemorrhagic Hypovolemic shock Traumatic hypovolemic
shock (narrower sense) shock
Resulting from acute resulting from acute resulting from external or resulting from a critical
hemorrhage without major hemorrhage with soft tissue internal fluid loss coupled with reduction in circulating plasma
soft tissue injury injury and, in addition, release inadequate fluid intake i.e. volume without acute
of immune system activators diarrhea, vomiting, diabetes hemorrhage, due to soft tissue
insipidus, liver cirrhosis injury and the release of
immune system mediators.
Hypovolemic Shock

Hemorrhagic shock
Clinically the most significant cause of hemorrhagic shock is acute bleeding from
an isolated injury to a large blood vessel:
1-Gastrointestinal bleeding

2-Nontraumatic vascular rupture (e.g., aortic aneurysm)

3-Obstetric hemorrhage (e.g., ectopic pregnancy)

4-Hemorrhage in the region of the ear, nose, and throat (vascular erosion)
Hypovolemic Shock

Traumatic Hemorrhagic shock

This type of shock is distinguished from hemorrhagic shock by the additional
presence of major soft tissue injury which aggravates the shock.

Polytrauma patients (RTA)

Diffuse bleeding, hypothermia (especially = 34 °C), and acidosis lead to life-

threatening coagulopathy. The soft tissue injury leads to post-acute inflammation,
further reinforcing this process.
Hypovolemic Shock

Traumatic Hypovolemic shock

Arises from large surface burns, chemical burns, and deep skin lesions. The
trauma also activates the coagulation cascade and the immune system,
potentiating the impairment of the macro- and microcirculation. The
inflammatory reaction results in damage to the endothelium, increases capillary
leak syndrome, and causes severe coagulopathy
Treatment of Hypovolemic Shock

1- Immediate intravascular volume replacement (with balanced crystalloids) using wide

bore peripheral venous access
2- In patients with controllable bleeding Red Blood Cells Concentrates (RCCs) transfusion is
indicated; while in patients with uncontrolled bleeding, give RCCs, Fresh Frozen Plasma
(FFP), and Platelets concentrates (PC).
3- Traumatic patients should be given early 1-2gm tranexamic acid at early stage (inhibit
fibrinolysis).
4- Patients with presisting hypotension after head trauma should be given norepinephrine
(vasoconstrictor)
5- Stabilize coagulation by coagulation factors of FFP transfusion.
6- Surgical control of bleeding (if hemorrhagic)
7- endotracheal intubation with normoventilation to prevent and treat hypoxia
Distributive Shock
Distributive Shock

Definition: A state of relative hypovolemia resulting from pathological redistribution of the absolute
intravascular volume and is the most frequent form of shock. The cause is either a loss of regulation of
vascular tone, with volume being shifted within the vascular system, and/or disordered permeability of the
vascular system with shifting of intravascular volume into the interstitium.

Subtypes
Septic shock Anaphylactic/anaphylactoid Neurogenic Shcok
shock
Dysregulated response by the Is characterized by massive is a state of imbalance between sympathetic and
body to an infection resulting in histamine-mediated vasodilation parasympathetic regulation of cardiac action and
life-threatening organ and maldistribution with a shift of vascular smooth muscle. The dominant signs are
dysfunctions. fluid from the intravascular to the profound vasodilation with relative hypovolemia
extravascular space. while blood volume remains unchanged, at least
initially.
Distributive Shock

Septic shock
Sepsis — The core of the pathophysiology is the endothelial dysfunction, which leads
to dysregulation of vascular tone resulting in vasodilation, impaired distribution, and
volume shifting in the macro- and microcirculation, and to a rise in vascular
permeability (capillary leak syndrome)

Toxic shock syndrome

TSS is characterized by fever, severe hypotension, and skin rash as the main symptoms. It
is usually triggered by toxins from certain staphylococci. The incidence is 0.5 / 100 000,
and mortality is between 2% and 11%. Treatment is the same as that recommended for
septic shock.
Distributive Shock (TTT Septic)

1- Immediate intravascular volume replacement (with balanced crystalloids) using wide

bore peripheral venous access.
2- Vasopressors (such as norepineherine) and inotropic drugs (dobutamine)
3- Advanced invasive monitoring to allow tailored therapy for impaired hemodynamics
(echocardiography is essential)
4- Broad spectrum antibiotic therapy should start immediately + blood cutlure
5- endotracheal intubation with normoventilation to prevent and treat hypoxia (may be
indicated)
Distributive Shock

Anaphylactic/anaphylactoid shock
Anaphylaxis is an acute systemic reaction usually mediated by IgE-dependent
hypersensitivity reactions. The central role is played by mast cells and the histamine they
release.

The most frequent trigger Whereas in adults it is insect Drugs (21%, two-thirds of these
in children is food products venom (55%, of which 70% being diclofenac, acetylsalicylic
(58%) are wasp stings and 20% bee acid, and antibiotics, and 1% being
stings) ACE inhibitors or beta-blockers).
Distributive Shock (TTT Anaphylactic)

1- Immediate intravascular volume replacement (with balanced crystalloids) using wide

bore peripheral venous access.
2- Vasopressors (such as norepineherine and epinepherine) and inotropic drugs
(dobutamine)
3- Monitoring of vital signs to allow tailored therapy for impaired hemodynamics
4- Anti-histamincs
5- In patients with bronchospasm, ß-sympathomimetics and, as second-line treatment,
glucocorticoids are indicated
5- Endotracheal intubation with normoventilation to prevent and treat hypoxia (may be
indicated)
Distributive Shock

Neurogenic shock
• Direct injury to the centers for circulatory regulation due to compression (brainstem trauma), ischemia
(e.g., basilar artery thrombosis), or the influence of drugs
• Altered afferents to the circulatory center in the medulla oblongata due to fear, stress, or pain or
dysregulated vagal reflexes
• Interruption of the descending connection from the bulbar regulatory centers to the spinal cord,
especially in patients who have sustained trauma above the middle of the thoracic spine (paraplegia).

Neurogenic shock is characterized by the sudden drop of SAP to <100

mmHg and heart rate to <60/min with decreased consciousness (rapid
onset in bulbar injury) and, in patients with high spinal cord injury, loss
of spinal reflexes
Distributive Shock (TTT neurogenic)

1- Immediate intravascular volume replacement (with balanced crystalloids) using wide

bore peripheral venous access.
2- Vasopressors (such as norepineherine and epinepherine) and inotropic drugs
(dobutamine)
3- Monitoring of vital signs to allow tailored therapy for impaired hemodynamics
4- Treatment of the cause is the corner stone of treatment of neurogenic shock
Cardiogenic Shock
Cardiogenic Shock

Definition: Cardiogenic shock is primarily a disorder of cardiac function in the form of a

critical reduction of the heart’s pumping capacity, caused by systolic or diastolic
dysfunction leading to a reduced ejection fraction or impaired ventricular filling.

Clinical Diagnosis
Systemic Arterial Pressure (SAP) Mean Arterial Pressure (MAP)
<90 mmHg decreased by 30 mmHg or more from baseline

Together with evidence of cardiac dysfunction and exclusion of other types of shocks
Cardiogenic Shock

The cardiac dysfunction may be due to myocardial, rhythmologic, or mechanical

causes:

Myocardial Rhythmologic Mechanical

Reduction of pump function due to Mechanical causes include advanced acute

Tachycardia and
acute coronary syndrome (ACS) is the and chronic valvular disease and
bradycardia may also
preeminent cause. Other causes mechanical complications after myocardial
result in the clinical picture
include various cardiomyopathies, infarction or caused by intracavitary
of cardiogenic shock.
myocarditis, pharmacotoxicity, and structures impeding flow (thrombi or
blunt trauma to the heart tumors).
Cardiogenic Shock

The main symptoms of cardiogenic shock are agitation, disturbed

consciousness, cool extremities, and oliguria. Death in patients in
cardiogenic shock is usually caused by hemodynamic instability,
multiorgan failure, and systemic inflammation.
Cardiogenic Shock (TTT)

1- Removal of the primary cause of cardiogenic shock (i.e. cardiac stents)

2- Immediate intravascular volume replacement (with balanced crystalloids) using wide
bore peripheral venous access.
2- Vasopressors (such as norepineherine) and inotropic drugs (dobutamine)
3- Advanced invasive monitoring to allow tailored therapy for impaired hemodynamics
(echocardiography is essential)
4- Anti-arrythemic drugs
5- endotracheal intubation with normoventilation to prevent and treat hypoxia (may be
indicated)
Obstructive Shock
Obstructive Shock

Definition: Obstructive shock is a condition caused by the obstruction of the great

vessels or the heart itself. Although the symptoms resemble those of cardiogenic shock,
obstructive shock needs to be clearly distinguished from the latter because it is treated
quite differently

The symptoms of obstructive shock are nonspecific and the condition is

characterized by the compensatory autonomic response in the form of tachycardia,
tachypnea, oliguria, and altered consciousness. Hypotension may be quite modest
initially and this can lead to underestimation of the clinical situation
Obstruction of intrathoracic blood flow can lead to cervical venous congestion or to
atypical peripheral pulses.
Obstructive Shock

Pathophysiology:
1- Disorders involving impaired diastolic filling and reduced cardiac preload include vena
cava compression syndrome, tension pneumothorax, pericardial tamponade, and high-
PEEP ventilation.
2- A pulmonary artery embolism or mediastinal space-occupying mass increases right-
ventricular afterload, while at the same time left ventricular preload is reduced by
obstructions in the pulmonary flow. The same mechanisms occur with an intracardial
mass.
Treatment:
1- Treatment of the primary cause
2- General measures of shock treatment
FIRST AID

Assessment of the (LOC) level of

consciousness using AVPU:
• A—Alert: acknowledge rescuers
presence and engage in interaction
• V—Verbal: respond to verbal stimuli
• P—Pain: have a response to painful
stimuli
• U—Unresponsive
FIRST AID

A-B-C-D-E-H:
• A—airway: it is important to assess the
patient’s airway patency with C-spine
protection

• B—Breathing & ventilation: ensure that the

breathing is sufficient to support life and
detect any structural injuries to the chest
FIRST AID

A-B-C-D-E-H:
• C—Circulation: Monitor patients blood pressure,
with pulse check, and ECG.

• D—Disability: re-assess and evaluate the LOC

• E—Exposure: expose the affected area

• H—History: complete history if possible