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EM - EBMedicine Summaries > Shock > Flashcards

Shock Flashcards

Diagnosis and Management of Shock in the Emergency Department (March 2014)

1
Q

What are four categories of shock?

A
  1. Hypovolemic
  2. Distributive
  3. Cardiogenic
  4. Obstructive
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2
Q

What is the equation for the delivery of oxygen to peripheral tissues?

A

DO = CO * ( Hb * SaO2 * 1.39 ) + ( PaO2 * 0.003 )

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3
Q

How does mean arterial pressure relate to cardiac output and systemic vascular resistance?

A

MAP = CO * SVR

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4
Q

How does cardiac output relate to heart rate and stroke volume?

A

CO = HR * Stroke Volume

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5
Q

What are the three goals of treating shock?

A
  1. Restore Perfusion
  2. Restore Oxygen delivery
  3. Treat underlying cause
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6
Q

Categories of Shock: Hypovolemic

(1) What are the hemodynamic changes that occur
(2) Causes [4]

A

(1)
Decreased Preload –> Decreased Cardiac Output
Increased SVR

(2)
Hemorrhage
GI Loss
Burns
Third Spacing
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7
Q

Categories of Shock: Distributive

(1) What are the hemodynamic changes that occur
(2) Causes [7]

A

Decreased SVR –> Decreased Preload
CO can be increased or decreased

(2)
Sepsis
Anaphylaxis
Neurogenic Shock
Pancreatitis
Liver Failure
Adrenal Insufficiency
Transfusion Reactions
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8
Q

Categories of Shock: Cardiogenic

(1) What are the hemodynamic changes that occur
(2) Causes [5]
(3) Most common cause

A

Decreased Cardiac Output –> Increased Preload / SVR

(2) 
Myocardial Infarction  **MCC**
Symptomatic Bradycardia
Heart Blocks
Valvular Disease
End-stage heart failure
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9
Q

Categories of Shock: Obstructive

(1) What are the hemodynamic changes that occur
(2) Causes [6]

A

Either a critical decrease in preload or increase in left ventricle outflow obstruction: Decreased CO –> Inc. SVR

(2) 
PE
tPNX
Positive-pressure ventilation
pHTN
pericardial tamponade
Abdominal herniation
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10
Q

Cardiomyopathy in Sepsis

(1) Prevalence
(2) Physiology
(3) Mortality

A

(1) Up to 40% of patients with distributive shock due to sepsis may develop transient cardiomyopathy
(2) Unclear process but leads to decreased left ventricular inotropy and decreased cardiac output
(3) Up to 70% mortality

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11
Q

What are the etiologies of Cardiogenic Shock (8)

A
  1. Acute Myocardial Infarction
  2. Mechanical Complications of Infarction
    - Acute MR
    - VSD
    - Free wall rupture
  3. Myocarditis
  4. Cardiomyopathy
    - Cardiomyopathy
    - Hypertrophic
    - Restrictive
    - Takotsubo
  5. Cardiac Trauma
  6. Transplant Rejection
  7. Atrial Myxoma
  8. Tachy/Bradyarrhythmias
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12
Q

What are causes of dilated cardiomyopathy (9)

A
  1. Ischemic
  2. Viral/bacterial
  3. Toxic
  4. Peripartum
  5. Thyroid
  6. Pheochromocytoma
  7. Rheumatologic
  8. Sarcoidosis
  9. Congenital
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13
Q

What is the sensitivity of HR with (1) Moderate Blood Loss (2) Major Blood Loss // Sensitivity of decreased BP

A

Increase in heart rate > 30 bpm is

(1) Only 22% sensitive for blood loss of ~500mL
(2) 97% sensitive and 98% specific for blood loss of 600-1000mL

Decrease in SBP > 20mmHg is not helpful to assess for blood loss

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14
Q

What is required to perform ABCs?

A 
1. A : Airway
One question: Do I need to inbutate? 
- Decreased MS
- Impending respiratory failure
- Poor clinic trajectory
  1. B : Breathing
    Two questions:
    - Is there symmetric air movement?
    - Is there equal chest rise and fall?
  2. C : Circulation
    One question:
    - Are there central pulses?
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15
Q

In the patient with shock, what is the sensitivity and specificity of Cap Refill and Skin Temperature for diagnosing distributive shock?

A

89% sensitive
68% specific

[JS - Translation: ~90% sensitive, specific greater than 2/3rd time]

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16
Q

What are labs to get with the shock patient?

A

CBC
Chem7
VBG/ABG/Lactate
Blood Cx’s (before antibiotics)

Consider:
LFTs
Troponin
ScvO2

17
Q

Base Deficit

(1) What is it?
(2) Significance
(3) confounder of interpretation

A

(1) Decrease in basic molecules in the blood, primarily bicarb
- Typically due to metabolic acidosis but also seen in respiratory acidosis
(2) Worsening base deficit associated with increasing morbidity
(3) Can be affected by IVF containing bicarb

18
Q

What is the ultrasound view to differentiate CVP < 10 from CVP > 10

A

Maximal IVC diameter

vs. IVC inspiratory collapse and IJ height:width ratio

19
Q

What is a limitation of using a portal CXR?

A

AP Portable CXR has limited view of the posterior lungs

20
Q

What percentage of hypotensive patients are fluid responsive? What bedside test can be done to assess for fluid responsiveness? For intubated patients?

A

approximately 50%

(2) Passive leg raise (from horizontal to vertical position) while on cardiac monitor

(3) Evaluation of pulse-pressure variation between end-expiratory and end-inspiratory.
- Variation > 13% suggests pt is preload dependent and fluid response.
- Requires Mechanical Ventilation and A-line

21
Q

ScvO2

(1) What is it
(2) What is normal
(3) Interpreting low ScvO2
(4) Interpreting high ScvO2
(5) Significance

A

(1) Central venous oxygen saturation
(2) 70-89%
(3) Hypoxia < 70
- Poor perfusion
- Decreased Hb carrying capacity
- Increased peripheral tissue use of oxygen
(4) Hyperoxia > 90
- Microcirculatory failure
- Mitochondrial function
(5) Hyperoxia and Hypoxia both linked with increased mortality

22
Q

What are unnecessary things in shock resuscitation in the ED?

A

NO colloids
NO starches
NO pulmonary artery catheters
NO A-lines (can be beneficial from prolonged resus but studies show no difference in outcomes)

23
Q

What are the four initial steps for managing shock?

A
  1. Immediate Actions
    - ABCs
    - Monitor (inc. SpO2 and BP cuff)
    - IV (consider CVL)
    - Vigilance for occult shock
  2. Develop Differential
    - What type of shock?
    - What etiologies?
  3. Focused H&P
  4. Continued Resus
    - Labs
    - Targeted Therapies
    - Reassess after each therapy
24
Q

When should vasopressors be started?

A

Once a patient is determined to be euvolemic, but there is still ineffective oxygen delivery

25
Q

How is prognosis affected by lactates taken in the first 6 hours of resus?

A

Every 10% increase in lactate clearance suggests a 11% decrease in mortality
- This marker is noninferior in prognosis to acheiving >70% ScvO2

26
Q

What are the common pregnancy related etiologies of shock? (6)

A 
Early: Ectopic with hemorrhage
Late:
- Sepsis
- Cardiomyopathy
- PE
- Amniotic fluid embolism
- Hemorrhage (post partum, uterine inversion, etc)
27
Q

Risks of intubating during sepsis

(1) Why?
(2) What to do

A

Acute hemodynamic collapse can occur due to:

  • Vasodilation from induction medications
  • Increased vagal tone from hypopharyngeal stimulation
  • Decreased RV preload with PPV
    (2)
  • Ensure vasopressors are on pumps and in-line with IVF
  • Provide peri-intubation volume resuscitation
28
Q

Steps to take with progressive shock

A

(1) Intubate
(2) CVL
(3) A-line

29
Q

Amniotic Fluid Embolism

(1) How does it happen?
(2) Mechanism of Shock

A

(1) Thought to occur due to:
- communication between placental and systemic veins
or
- tears in the cervix or uterus in the setting of ruptured membranes

(2) Unclear, but thought to be anaphylactoid secondary to immunogenic response from amniotic fluid exposure

30
Q

Should a history of low EF (eg < 10%) limit fluid resuscitation?

A

No! Ensure euvolemia regardless of setting of decreased EF

31
Q

Causes of Shock in Trauma

(1) Hypovolemic
(2) Distributive
(3) Cardiogenic
(4) Obstructive

A

(1) Hemorrhage
- hemothorax
- hemoperitoneum
- femur fracture
- pelvic fracture
- RP bleed

(2)
- Neurogenic Shock (strength, step offs, rectal tone)
- Fat emboli syndrome (pelvic, long bone fx)
- SIRS due to hemorrhage

(3)
- Cardiac contusion (ecg, u/s, troponin)

(4)
- tPNX
- Cardiac tamponade
- traumatic diaphragmatic hernia

32
Q

What MAP should raise concern for pathophysiologic process in pregnancy?

A

MAP < 60mmHg

normal pregnancy changes only result in decrease in MAP of 5-10mmHg

EM - EBMedicine Summaries (5 decks)

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