Shock

Question 1

Define shock

Answer 1

A severe imbalance between the oxygen supply and demand, leading to inadequate cellular energy production
-most commonly due to a significant decrease in oxygen delivery that is then not able to supply the needs of oxygen consumption in tissues
- can also be due to greatly increased oxygen consumption (ex: cluster seizures)

Question 2

What are the different factors that play into oxygen delivery?

Answer 2

Oxygen delivery is a product of cardiac output and the arterial content of oxygen
- cardiac output= HR (influenced by sympathetic/parasympathetic NS) X SV (influenced by preload, afterload and contractility)
- arterial content of O2= (1.34 X hemoglobin X SaO2) + (0.003 X PaO2)

Question 3

What are the main consequences of shock?

Answer 3

1. Na/K ATPase dysfunction
2. cellular necrosis and apoptosis
3. acidemia
4. endothelial dysfunction
5. activation of inflammatory and coagulation cascades
6. multiorgan dysfunction syndrome
7. death

Question 4

What is the first cardiac chamber affected by pericardial effusion?

Answer 4

Right atrium (at the lowest pressure in the heart)
- will collapse in on itself

Question 5

What are the compensatory mechanisms that the body initiates in a state of shock?

Answer 5

Decreased stretch of blood vessels send a signal to the vasomotor center in brain
- causes increased sympathetic tone and decreased parasympathetic tone

Causes direct release of catecholamines from the adrenal glands- increase HR, contractility and peripheral vasoconstriction

1. Baroreceptor reflex leads to increased HR, cardiac contractility, and peripheral vasoconstriction
2. Chemoreceptors (senses changes in pH, oxygen levels) cause an increase respiratory rate and todal volume
3. RAAS activation –> ADH which causes peripheral vasoconstriction and renal Na+/water absorption

Question 6

How do you diagnose shock?

Answer 6

It is a clinical diagnosis based on physical exam
- one abnormality can be enough to diagnose(decrease in HR, pulse quality, pale mucous membranes, decreased CRT, hypothermia, altered mentation)

Question 7

What is the problem with using decreased BP as the hallmark of decompensation?

Answer 7

It is affected by many other systems other than stress
-you can have poor tissue perfusion with a normal BP
-BP equipment we often have is not very reliable

DONT REDUCE A PATIENT TO A SINGLE BP VALUE

Question 8

Describe the difference in clinical signs in anaphylactic and septic shock compared to the others?

Answer 8

Tachycardia, CRT <1 s, red to injected MM, elevated temperature, bounding pulses

Question 9

What are the differences you see in clinical signs of shock in cats?

Answer 9

• mucous membranes hard to assess (due to temperament and pale gums)
• hypothermia can occur in any type of shock (usually due to cardiogenic shock in dogs)
• bradycardia (sign of shock until proven otherwise)
  -rarely manifest signs of vasodilatory shock
  -cats can get tachypneic/enter respiratory distress for a variety of shock reasons (not necessarily just a problem with the lungs)

Question 10

What are some good ways to try to determine if a shock presentation is cardiogenic in origin?

Answer 10

• abnormal rhythm on ausculation or murmur present
• signalment/history of heart problems
• respiratory distress
• coughing in dogs
• jugular venous distension
• ascites
• pleural or pericardial effusion
• pulmonary crackles
• arrythmia
• syncope

Question 11

What should be your plan of action after you determine a patient is in shock?

Answer 11

-perform a head to tail exam
- perform point of care tests- PCV/TS, blood glucose, lactate, blood pressure, ECG, POCUS, acid-base and electrolyte panel
-once stable get CBC/chem/UA, chest X rays, abdominal X rays or ultrasound, echocardiogram, fluid analysis, bacterial cultures, etc

Question 12

What is the goal of shock treatment?

Answer 12

To restore oxygen delivery to tissues as soon as possible
- start with flow by oxygen, obtaining IV access and IV fluids bolus (except in cardiogenic shock cases)

Question 13

What is the mainstay of therapy for fluid resuscitation in shock cases?

Answer 13

Isotonic crystalloids (LRS, normosol R, plasmalyte A, isotonic saline)
- 5-20 mL/kg over 10-20 min
- repeat as needed for up to 90 mL/kg in dogs and 66 mL/kg in cats (give 1/4 to 1/5 at a time and always reassess in between boluses)

Additional options include hypertonic saline, synthetic/natural colloids, or whole blood/component therapy

Question 14

How often should you reassess shock patients?

Answer 14

Every 5-10 minutes or after every therapeutic intervention during stabilization
- once normal perfusion parameters (aka successful resuscitation), can de-escalate monitoring and therapy