1 - Shock Flashcards
What is shock?
Inadequate oxygen to meet metabolic/tissue demands
Does shock mean hypotension?
No it can be normal, increased, or decreased
What shock is from an inadequate blood volume or oxygen carrying capacity?
Hypovolemic Shock
Hemorrhagic Shock
What shock is from inappropriate distribution of blood volume and flow?
Distributive Shock
What shock is from impaired cardiac contractility
Cardiogenic Shock
What shock is from obstructed blood flow?
Obstructive Shock
Main function of the cardiopulmonary system
deliver O2 to body tissues and remove metabolic by products of cellular metabolism (CO2)
When O2 is inadequate to meet tissue demand
Cells use anaerobic metabolism - to produce energy
= LACTIC ACID
Oxygen delivery to the tissues is dependent on…
Arterial O2 content (oxygen bound to hemoglobin plus dissolved O2)
Cardiac output (volume of blood pumped each minute)
Arteries vs veins
Arteries carry O2
Veins carry blood back through the vena cava to be reoxygenated
O2 may be normal despite hypoxemia due to what compensation
CO increasing
When hypoxemia is chronic what does hemoglobin concentration due
increases - polycythemia
Therefore increasing the O2 carrying capacity of the blood
CO =
SV X HR
CO
SV
HR
CO - (the volume of blood pumped by the heart in each minute)
SV - The amount of blood pumped by the left V with each contraction
HR - Number of times the ventricles contract per minute
Infants are more dependent on CO or HR?
very small SV - dependent on HR
Preload
Volume of blood present in the ventricle before contraction
Contractility
Strength of contractin
Afterload
Resistance against which the ventricle is ejecting
Inadequate preload is the most common cause of
hypovolemic shock
Inadequate contractility is the most common cause of
Cardiogenic Shock
Increased afterload can cause
cardiogenic shock
what is pulse pressrue
the distance between systolic and diastolic pressure
If SVR is low (as in sepsis) what happens to the pulse pressure
diastolic pressure decreases and pulse pressure widens
Compensated shock.
Maintain a systolic pressure
Compensated shock clinical symptoms
tachycardia (vasoconstriction) decreased UO (Retaining water) delayed cap refill (send blood to peripheral)
Pulses in compensated shock
Narrow pulse pressure (increase in diastolic)
In most types of shock what is hypotension
a late finding
what is hypotension in septic shock?
When SVR is decreased due to the mediators of sepsis - hypotension will be an early sign
(brisk cap refill, full pulses)
Hypotensive forumla
70 + (Age in years X 2)
How long can it take compensated shock to turn into hypotensive shock
Possibly hours
Hypotensive Shock to Cardiac arrest?
Possibly mintues
Hypovolemic shock etiology
Gastroenteritis, burns, hemorrhage, inadequate fluid intake, body fluid loss, osmotic diuresis
Cardiogenic shock etiology
CHD, myocarditis, cardimyopathy, arrhythmia
Distributive shock etiology
DIS (3)
Sepsis
Anaphylaxis
Spinal cord injury
Obstructive
tension pneumo, cardiac tamponade, PE, constriction of the ductus arteriosus in infants with ductal-dependent CH lesions (coarctation, hypoplastic left ventricle)
Hypovolemic shock is typically a depletion of both
intravascular and extravascular fluid volume
What type of fluid boluses are required for hypovolemic shock
Fluid boluses that exceed the volume of the intravascular deficit due to extravascular deficit as well
What respiratory compensation is used in hypovolemic shock
typically tachypnea - creates respiratory alkalosis - blowing off CO2
Partially compensating for metabolic acidosis (lactic acidosis) that accompanies shock
Hypovolemic shock is characterized by a
decrease preload leading to reduced SV and low CO
Hypovolemic shock main compensatory mechanisms
Tachycardia
Inc SVR
Increased cardiac contractility
Relative hypovolemia
Arterial/Venous vasodilation
Increased capillary permeability
Plasma Loss into the interstitum
= Third spacing
A clinical finding that separetes hypovolemic shock from other shocks
Narrow pulse pressure
Adequate or hypotensive systolic pressure
Increased diastolic resistance - increased both to try and compensate
Distributive shock includes
Septic
Anaphylactic
Neurogenic (spinal injury)
Distributive shock is characterized by
dec SVR leading to maldistribution of blood volume and flow
In septic and distributive shock there is decreased..
cell permeability .. leading to loss of volume from the intravascular space - decreased preload
In neurogenic shock there is decreased..
sympathetic tone, leading to vasodilation and lack of compensatory mechansims
Distributive shock characteristics
- Volume depletion due to capillary leak
- Rlease of inflammatory / vasoactive substances
- Inadequate perfusion of the splanchnic (gut and kidney)
- Inc blood flow to peripheral tissue beds
- Accumulation of lactic acid
- Low SVR
The inflamatory cascade response to sepsis
- Infectious organism activates the immune system (neutrophils, monocytes, macrophages)
- These cells stimulate release of inflammatory mediators (cytokines)
- Cytokines produce vasodilation and damage to the lining of the bv causing increased cap permeability
- Cytokines activate the coagulation cascade (microvascular thrombosis or DIC)
- Specific inflammatory mediators can impair cardiac contractility and cause dysfunction
What makes sepsis so hard to treat?
The variability of perfusion throughout the body
What is septic shock caused by
Infectious organism that cause the small blood vessels to dilate and to leak fluid into the tissues
What glands have insufficiency in septic shock (explain)
adrenal glands - prone to microvascular thrombosis
Neurogenic shock results from what level
T6 and above
What are the compensatory mechanisms of neurogenic shock
None due to the sympathetic system being interupted
What separates hypovolemia from cardiogenic shock
Hypovolemia is quiet tachypnea
While cardiogenic is retractions, grunting, use of accessory muscles - pulmonary edema
Fluid refill in cardiogenic shock for peds
5-10 ml/kg boluses over 10 to 20 minutes
Simple pneumo
air leak that enters the pleural space but stops spontaneously
Specific findings in tension pneumo
Tracheal deviation
Hyperresonance on the affected side
Hyperexpansion on the affected side
PE is
a total or partial obstruction of the pulmonary artery or its branches by a clot, air, amniotic fluid, catheter fragment
What is glucose used for
vital for proper cardiac and brain function
Hypoglycemia can lead to seizures and brain injury
What is calcium used for
Cardiac function and vasomotor tone
How does sodium bicarb work in acidosis
Sodium bicarb combines with hydrogen ions = carbon dioxide and water
CO2 is then eliminated through alveolar ventilation
Fluid resuscitation rate
20ml/kg over 5 to 20 mins
Inotropes work by
Increase cardiac contractility
Increase HR
Inotropes drugs
Dopamine
Epi
Dobutamine
Phosphodiesterase ihibitors work by
Decrease SVR
Improve coronary artery blood flow
Improve contractility
Phosphodiesterase examples
Milrinone
Vasodilator examples
Nitro
Vasopressor examples
NEVD
Epi (>0.3 mcg/kg a minute)
Norephinephrine
Dopamine (>10mcg/kg a minute)
Vasopressin
What fluid is usually used for shock
isotonic crystalloids will expand intravascular volume
Blood is usually only used for hemorrhage
Other fluid rates for hypotensive and septic shock
60 ml/kg or 200m/kg
DKA osmolality
Significantly dehydrated - hyperglycemia
What happens with rapid fluid fix in DKA
Cerebral edema
Fluid resuscitation in DKA
10 to 20 ml/kg over 1 to 2 hours
Posoning fluid resuc (CCB - B blockers)
5-10ml/kg bolus over 10-20 mins
Dextrose dosage for symptomatic child
D25W : 2-4ml/kg
D10W: 5-10ml/kg
Hemorrhagic sock resuscitation
3ml of isotonic crystalloid for every 1ml of blood loss
