4. Shock (CV)

What is shock?

cellular and tissue hypoxia due to

• decreased oxygen delivery

• increase oxygen consumption

• inadequate oxygen utilization

• or combo of all

inadequate oxygen to tissues = organs start to fail

If shock is irreversible what will happen?

won’t react to therapy = organs die

What are the signs and symptoms

• Decrease in BP but increase in HR

• Thirst

• Decreased or absent urine output (kidneys failing)

• rapid, laboured breathing

• cold, dusky, clammy extremities

How does the body compensate?

• activates sympathetic nervous system

• Increase in HR = vasoconstriction

• urine decreases as renal perfusion decreases

• RR and depth increase = to elevate blood oxygen levels to comp for acidosis

What are the 3 effects of shock to the cells?

1. Impaired Oxygen use

• tissue uptake is inhibited

• cell function is impaired and disrupted

2. Acidosis

• anaerobic metabolism = metabolic acidosis

• enzymes break down

• cell repair, function and division is impaired

3. Impaired glucose use

• delivery and use is impaired

• cell metabolism suffers

What happens to the CVS in regards to shock?

• Ventricular failure

• 3rd space fluid (fluid into interstitial space)

• DIC (Disseminated intravascular coagulopathy)

What happens to the neurological system in regards to shock?

• heart and respiratory drives can be altered

• thermoregulation can be hard to do

• coma if perfusion and oxygen delivery drops too far

What happens to the renal system in regards to shock?

• acute tubular necrosis and loss of function that persists after perfusion is impaired

What happens to the gastro-intestinal system in regards to shock?

• necrosis

• infarction

• ischemia

What is hypovolemia shock?

Severe blood or fluid loss

What are the 2 sub categories for hypovolemia?

1. Absolute

2. Relative

What is absolute hypoveolmia?

External loss of fluid (volume loss from body)

• loss of blood (trauma/hemorrhage)

• loss of plasma (burns)

• loss of fluids (vomiting, diarrhea)

What is relative hypovolemia?

Total volume retained but not distributed between central and peripheral compartments

• PPV

• Venous dilation

Is the volume deficit is <15% what will happen?

CO will likely not drop

If volume loss is 15-30% what happens?

Body will try and compenstate

Stage 1 of hypovolemic shock

• CO drops = try to compensate

  • Increase HR

  • Pulse pressure narrows (systolic vs diastolic)

  • Increase RR

  • Decrease urine output

  • pale and cool

Stage 2 of hypovolemic shock

• Fluid loss 30-40% = start to decompensate

  • HR increases

  • respiratory distress

  • kidneys start to fail

  • decreased LOC

  • skin changes

Stage 3 of hypovolemic shock

Refractory shock >40% loss

• compensation has failed

• organs fail

• tachycardia & hypotension

• no peripheral pulse

• cyanosis

• diaphoretic

What is the trx for hypovolemic shock?

1. Control volume loss

2. Replace loss with like things

• Give crystalloids for fluid

• Give blood products for blood loss

What is cardiogenic shock?

LV fails to pump blood forwards

• due to issues with SV or HR

What are some possible causes of cardiogenic shock?

• brady or tachycardias

• cardiomyopathy

• trauma

• valvular failure

What is the most common cause of dysfunction for cardiogenic shock?

MI

• if MI results in 40% or more myocardial injury = ineffective contraction

• damage could be from one big MI or many small MI’s

Steps of Cardiogenic shock compensation

1. CO drops = renal system responds to maintain blood volume

• Fluid is retained and U/O decreased

2. Catecholamines = increase SVR, contractility and rate

3. Myocardial oxygen consumption increases further

4. Heart cannot maintain output = tissue perfusion decreases

Signs and symptoms of cardiogenic shock

• cold, clammy extremities

• tachycardia

• BP sys <90

• chest pain

• weak and thready pulse

• dysrhytmias

• decreased CO and S1/S2 sounds

• JVD

• Tachypnea with hypocapnea

• Hypoxemia

• crackles

• deceased LOC

• Decreased U/O

• increased SVR, CVP, PCWP

Treatment for cardiogenic shock

• Fluid (crystalloids)

• Inotropic support

• Vasopressor support (increase BP)

• Further cardiac workup

  • revascularization

  • stents

  • grafts

  • ventricular assist devices

What is obstructive shock

Critical drop in CO where flow into heart or out of heart is inhibited

What can cause obstructive shock

Preload issues (stretch):

• large venous thrombus (Clot)

• tension pneumo

• cardiac tamponade (blood around heart)

• herniation of abdominal content into thorax

Afterload issues (resistance):

• significant PHTN

• pulmonary embolism

Treatment of obstructive shock

Reversal of obstruction

What is distributive shock?

Inappropriate vascular tone

• profound vasodilation causes BP to drop and forward flow of blood to diminish

• venous return to heart drops and SV drops

• changes in intra-vascular volume or cardiac function

3 subcategories of distributive shock

1. Neurogenic

2. Anaphylactic

3. Septic

What is neurogenic shock

Manifests as massive widespread vasodilation - creates relative hypovolemia (cardiac function drops as if volume has been lost)

• started by: increased parasympathetic activity or inhibited sympathetic activity

Causes of neurogenic shock

• spinal cord trauma

• medulla hypoxia and or hypoglycemia

• neuro-depressive drugs, anaesthetic agents, severe emotional distress or pain

Signs and symptoms of neurogenic shock

• bradycardia

• normal or high ejection fraction (shows myocardium is healthy)

• low CVP

Treatment of neurogenic shock

• Follows general shock management but

  • need to determine specific cause

  • potential surgical intervention

What is anaphylactic shock

• systemic inflammatory response triggered by allergens

What causes anaphylactic shock

• vasodilation

• increased vascular permeability

The allergic reaction leads to what?

• increased vascular permeability

• peripheral pooling

• edema

• bronchial SM constriction = increased WOB

Signs and symptoms of anaphylactic shock

• anxiety

• SOB

• bronchospasm

• wheezing, stridor

• gut cramps

• edema

• hives

• burning/itchy skin

• altered LOC with falling BP

Treatment of anaphylactic shock

• epi

• volume expanders

• antihistamines

• corticosteroids

• airway management (intubation, mechanical ventilation)

What is septic shock?

Presence of pathogens in blood stream

Typical pathways of septic shock

• infection

• bacteremia

• septicemia

• septic shock

• multi-organ dysfunction syndrome (MODS)

What do we see in septic shock

• vasodilation

• increased permeability

• extra-vascular fluid leakage

• histotoxic hypoxia: cells can’t use oxygen

What is the leading cause of death in ICU patients?

Septic shock

Septic shock is often caused by what type of bacteria

Gram negative

Bacteria causes sepsis in 2 ways

1. Directly from presence of bacteria

2. Toxins released by bacteria into blood

Sepsis inflammatory cascade

• Cellular messangers interact systemically

• vascular bed dilation, phagocytosis & apoptosis and haematological changes (clot) seen systemically

Cellular metabolism is effected in 3 ways in septic shock

1. Relative hypovolemia due to decreased SVR

2. action of infective agent

3. increased oxygen demands caused by fever and elevated production of immune cells

Signs and symptoms of septic shock

• low bp sys

• low SVR

• low oxygen extraction

• tachycardia

• cardiac output is variable

• temp instability

• multi organ failure

Treatment of septic shock

1. Antibiotics

2. fluid resuscitation

3. inotropic and vasoactive agents

4. airway and vent management

5. optimization of other failing organs

General shock treatment

• Euvolemia

  • crystalloids

• Vasopressors or inotropes

  • Dobutamine

  • epi

  • norepi

• Intubation and mechanical ventilation if WOB increased

Once they are stable what should we do?

• determine what type of shock based on history, presentation and diagnostics

• monitor and treat individually

Fluid managment

• assess BP, PCWP, U/O

• presense of edema

• pulse

• Svo2

• lactate

• watch for variance in pulse pressure (pulsus paradoxis) = fluid deprivation

Measuring SvO2

• Normal 60-80%

• lower = high tissue extraction from inadequate CO

• higher= sepsis so tissues can’t extract O2 from blood

need to draw with a central line

Why do we assess lactate and what is the normal?

Normal= 2mml/l

• associated with metabolic acidosis

What shock is HR low in?

Neurogenic

What shock is SVR high

Cardiogenic

Hypovolemic

What shock is CVP high

Cardiogenic

Obstructive

What shock is PAP high

Cardiogenic

septic

obstructive

What shock is PCWP high

Cardiogenic

What shock is CO variable

Septic

What shock is SVO2 variable

spetic