Tutorial

Tutorial:

باطنية
د. جاسم محمد طيب

عدد الأوراق10

20/11/2012

SHOCK

Shock is inadequate tissue perfusion.
Definition of Shock
Inadequate perfusion and oxygenation of cells
Inadequate perfusion and oxygenation of cells leads to:
Cellular dysfunction and damage
Organ dysfunction and damage

Why should you care?

High mortality - 20-90%
Early on the effects of O2 deprivation on the cell are REVERSIBLE
Early intervention reduces mortality


Pathophysiology
4 types of shock
Cardiogenic
Obstructive
Hypovolemic
Distributive

Pathophysiology: Overview

Tissue perfusion is determined by Mean Arterial Pressure (MAP)
MAP = CO x SVR


Heart rate Stroke Volume

Cardiogenic Shock: Pathophysiology
Heart fails to pump blood out

MAP = CO x SVR

HR Stroke Volume


Normal
MAP = CO x SVR

Cardiogenic

MAP = ↓CO x SVR
MAP = ↓CO x ↑ SVR
↓MAP = ↓↓CO x ↑ SVR

Cardiogenic Shock

The heart cannot pump enough blood to meet the metabolic demands of the body.

Cardiogenic Shock: Causes

MAP = CO (HR x Stroke Volume) x SVR

Decreased Contractility (Myocardial Infarction, myocarditis, cardiomypothy, Post resuscitation syndrome following cardiac arrest)
Mechanical Dysfunction (Papillary muscle rupture post-MI, Severe Aortic Stenosis, rupture of ventricular aneurysms etc)
Arrhythmia (Heart block, ventricular tachycardia, SVT, atrial fibrillation etc.)
Cardiotoxicity (B blocker and Calcium Channel Blocker Overdose)


Obstructive Shock: Pathophysiology
Heart pumps well, but the output is decreased due to an obstruction (in or out of the heart)

MAP = CO x SVR

HR x Stroke volume
Normal
MAP = CO x SVR

Obstructive

MAP = ↓CO x SVR
MAP = ↓CO x ↑ SVR
↓MAP = ↓↓CO x ↑ SVR

Obstructive Shock: Causes

↓MAP = ↓ CO (HR x Stroke Volume) x ↑SVR

Heart is working but there is a block to the outflow

Massive pulmonary embolism
Aortic dissection
Cardiac tamponade
Tension pneumothorax


Obstruction of venous return to heart
Vena cava syndrome - eg. neoplasms, granulomatous disease
Sickle cell splenic sequestration

Hypovolemic Shock: Pathophysiology

Heart pumps well, but not enough blood volume to pump

MAP = CO x SVR


HR x Stroke volume

Normal
MAP = CO x SVR

Hypovolemic

MAP = ↓CO x SVR
MAP = ↓CO x ↑ SVR
↓MAP = ↓↓CO x ↑ SVR

Blood Pressure and Volume

Hypovolemic Shock: Causes
↓MAP = ↓ CO (HR x Stroke Volume) x ↑SVR

Decreased Intravascular volume (Preload) leads to Decreased Stroke Volume

Hemorrhagic - trauma, GI bleed, AAA rupture, ectopic pregnancy
Hypovolemic - burns, GI losses, dehydration, third spacing (e.g. pancreatitis, bowel obstruction), Adesonian crisis, Diabetic Ketoacidosis

Distributive Shock: Pathophysiology

Heart pumps well, but there is peripheral vasodilation due to loss of vessel tone

MAP = CO x SVR


HR x Stroke volume

Normal

MAP = CO x SVR

Distributive

MAP = co x ↓ SVR
MAP = ↑co x ↓ SVR
↓MAP = ↑co x ↓↓ SVR


Distributive Shock: Causes
↓MAP = ↑CO (HR x SV) x ↓ SVR
Loss of Vessel tone
Inflammatory cascade
Sepsis and Toxic Shock Syndrome
Anaphylaxis
Post resuscitation syndrome following cardiac arrest
Decreased sympathetic nervous system function
Neurogenic - C spine or upper thoracic cord injuries
Toxins
Due to cellular poisons -Carbon monoxide, methemoglobinemia, cyanide
Drug overdose (a1 antagonists)

Neurogenic Shock

Spinal cord injury
Spinal anesthetic

Spinal cord injury

Spinal anesthetic
To Summarize
Types of Shock
Okits really not THAT simple


MAP = CO x SVR

HR x Stroke volume

Preload Afterload Contractility

Additional Compensatory Mechanisms

Renin-Angiotensin-Aldosterone Mechanism
AII components lead to vasoconstriction
Aldosterone leads to water conservation

ADH leads to water retention and thirst

Inflammatory cascade

Case 1

24 year old male
Previously healthy
Lives in a malaria endemic area (PNG)
Brought in by friends after a fight - he was kicked in the abdomen
He is agitated, and wont lie flat on the stretcher
HR 92, BP 126/72, SaO2 95%, RR 26


Stages of Shock



Case 1: Stages of Shock







Is this Shock?

Signs and symptoms
Laboratory findings
Hemodynamic measures

Symptoms and Signs of Shock

Level of consciousness
Initially may show few symptoms
Continuum starts with
Anxiety
Agitation
Confusion and Delirium
Obtundation and Coma
In infants
Poor tone
Unfocused gaze
Weak cry
Lethargy/Coma
(Sunken or bulging fontanelle)
Pulse
Tachycardia HR > 100 - What are a few exceptions?
Rapid, weak, thready distal pulses
Respirations
Tachypnea
Shallow, irregular, labored
Blood Pressure
May be normal!
Definition of hypotension
Systolic < 90 mmHg
MAP < 65 mmHg
40 mmHg drop systolic BP from from baseline
Children
Systolic BP < 1 month = < 60 mmHg
Systolic BP 1 month - 10 years = < 70 mmHg + (2 x age in years)
In children hypotension develops late, late, late
A pre-terminal event
Skin
Cold, clammy (Cardiogenic, Obstructive, Hemorrhagic)
Warm (Distributive shock)
Mottled appearance in children
Look for petechia
Dry Mucous membranes
Low urine output <0.5 ml/kg/hr
Empiric Criteria for Shock
4 out of 6 criteria have to be met
Ill appearance or altered mental status
Heart rate >100
Respiratory rate > 22 (or PaCO2 < 32 mmHg)
Urine output < 0.5 ml/kg/hr
Arterial hypotension > 20 minutes duration
Lactate > 4


Lactate
Lactate is increased in Shock
Predictor of Mortality
Can be used as a guide to resuscitation
However it is not necessary, or available in many settings

Management of Shock

History
Physical exam
Labs
Other investigations
Treat the Shock - Start treatment as soon as you suspect Pre-shock or Shock
Monitor

Historical Features

Trauma?
Pregnant?
Acute abdominal pain?
Vomiting or Diarrhea?
Hematochezia or hematemesis?
Fever? Focus of infection?
Chest pain?


Physical Exam
Vitals - HR, BP, Temperature, Respiratory rate, Oxygen Saturation
Capillary blood sugar
Weight in children
In a patient with normal level of consciousness - Physical exam can be directed to the history
In a patient with abnormal level of consciousness
Primary survey
Cardiovascular (murmers, JVP, muffled heart sounds)
Respiratory exam (crackles, wheezes),
Abdominal exam
Rectal and vaginal exam
Skin and mucous membranes
Neurologic examination

Laboratory Tests

CBC, Electrolytes, Creatinine/BUN, glucose
+/- Lactate
+/- Capillary blood sugar
+/- Cardiac Enzymes
Blood Cultures - from two different sites
Beta HCG
+/- Cross Match


Other investigations
ECG
Urinalysis
CXR
+/- Echo
+/- FAST
Treatment
Start treatment immediately


Treatment

ABCs
Airway
Breathing
Circulation
Put the patient on a monitor if available
Treat underlying cause

Treatment: Airway and Breathing

Give oxygen
Consider Intubation
Is the cause quickly reversible?
Generally no need for intubation
3 reasons to intubate in the setting of shock
Inability to oxygenate
Inability to maintain airway
Work of breathing


Treatment: Circulation
Treat the early signs of shock (Cold, clammy? Decreased capillary refill? Tachycardic? Agitated?)
DO NOT WAIT for hypotension
Start IV +/- Central line (or Intraosseous)
Do Blood Work +/- Blood Cultures
Fluids - 20 ml/kg bolus x 3
Normal saline
Ringers lactate

Back to Case 1

24 year old male
Previously healthy
Lives in a malaria endemic area (PNG)
Brought in by friends after a fight - he was kicked in the abdomen
He is agitated, and wont lie flat on the stretcher
HR 92, BP 126/72, SaO2 95%, RR 26

Case 1

On examination
Extremely agitated
Clammy and cold
Heart exam - normal
Chest exam - good air entry
Abdomen - bruised, tender, distended
No other signs of trauma


Case 1: Management
Hemorrhagic (Hypovolemic Shock)
ABCs
Monitors
O2
Intubate?
IV lines x 2, Fluid boluses, Call for Blood - O type
Blood work including cross match
Treat Underlying Cause
Hemorrhagic (Hypovolemic Shock)
ABCs
Monitors
O2
Intubate?
IV lines x 2, Fluid boluses, Call for Blood - O type
Blood work including cross match
Treat Underlying Cause
Give Blood
Call the surgeon stat
If the patient does not respond to initial boluses and blood products - take to the Operating Room


Blood Products
Use blood products if no improvement to fluids
PRBC 5-10 ml/kg
O- in child-bearing years and O+ in everyone else
+/- Platelets

Stages of Shock



Cardiogenic Shock

Treatment:
Oxygen
Monitors
Nitrates (if possible)
Morphine or fentanyl
Pressor support (dopamine or dobutamine)
If no pulmonary edema, consider small fluid boluses
IABP
Definitive therapy (fibrinolytic therapy, PTCA, CABG, ventricular assist device, cardiac transplant)
Vasopressors in Cardiogenic Shock
Norepinephrine
Dopamine
Epinephrine
Phenylephrine


Anaphylactic Shock
Drugs:
Penicillin and related antibiotics
Aspirin
Trimethoprim-sulfamethoxazole (Bactrim, Septra)
Vancomycin
NSAIDs
Other:
Hymenoptera stings
Insect parts and molds
X-Ray contrast media (ionic)
Foods and Additives:
Shellfish
Soy beans
Nuts
Wheat
Milk
Eggs
Monosodium glutamate
Nitrates and nitrites
Tartrazine dyes (food colors)


Treatment:
Airway (have low threshold for early intubation)
Oxygenation and ventilation
Epinephrine (IV, IM, Subcutaneously)
IV Fluids (crystalloids)
Antihistamines
Benadryl
Zantac
Steroids
Beta agonists
Aminophylline
Pressor support (dopamine, dobutamine or epinephrine)
Stages of Shock
Compensated
The bodys compensatory mechanisms are able to maintain some degree of tissue perfusion.
Decompensated
The bodys compensatory mechanisms fail to maintain tissue perfusion (blood pressure falls).
Irreversible
Tissue and cellular damage is so massive that the organism dies even if perfusion is restored.

Monitoring

Vitals - BP, HR, SaO2
Mental Status
Urine Output (> 1-2 ml/kg/hr)
When something changes or if you do not observe a response to your treatment -
re-examine the patient


Stages of Sepsis


Definitions of Sepsis

Systemic Inflammatory Response Syndrome (SIRS) 2 or > of:
-Temp > 38 or < 36
-RR > 20
-HR > 90/min
-WBC >12,000 or <6,000 or more than 10% immature bands
Sepsis SIRS with proven or suspected microbial source
Severe Sepsis sepsis with one or more signs of organ dysfunction or hypoperfusion.

Septic shock = Sepsis + Refractory hypotension

-Unresponsive to initial fluids 20-40cc/kg Vasopressor dependant
MODS multiple organ dysfunction syndrome
-2 or more organs

Stages of Sepsis



Pathophysiology

Complex pathophysiologic mechanisms
Inflammatory Cascade:
Humoral, cellular and Neuroendocrine (TNF, IL etc)
Endothelial reaction
Endothelial permeability = leaking vessels
Coagulation and complement systems
Microvascular flow impairment
End result = Global Cellular Hypoxia

Focus of Infection

Any focus of infection can cause sepsis
Gastrointestinal
GU
Oral
Skin

Risk Factors for Sepsis

Infants
Immunocompromised patients
Diabetes
Steroids
HIV
Chemotherapy/malignancy
Malnutrition
Sickle cell disease
Disrupted barriers
Foley, burns, central lines, procedures


Septic Shock
Treatment:
Airway and ventilatory management
Oxygenation
IV fluids (crystalloids)
Pressor support (dopamine, norepinephrine)
Empiric antibiotics
Removal of source of infection
NaHCO3?
Steroids?
Anti-endotoxin antibodie
Recom APC
Antibiotics
Early Antibiotics
Within 3-6hrs can reduce mortality - 30%
Within 1 hr for those severely sick
Dont wait for the cultures treat empirically then change if need.









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