Shock

Question 1

What is shock?

Answer 1

An imbalance between oxygen delivery to the tissues and the oxygen consumption by the tissue,

Question 2

Types of circulatory shock.
Define hypoperfusion/circulatory shock

Answer 2

Hypovolaemic
cardiogenic
Obstructive
Distributive

A critical condition that is brought on by a sudden and global deficit in tissue perfusion, resulting in inadequate delivery of oxygen and nutrients to vital organs.

Question 3

What does a reduced blood pressure result in?
How is BP calculated?
How is CO calculated?
What is SV determined by?

Answer 3

Reduced perfusion

Cardiac output (CO) X systemic vascular resistance (SVR)

HR x SV

Pre-load, afterload and the heart’s contractility.

Question 4

What is hypovolaemic shock?

Answer 4

Shock resulting in decreased blood volume.
Very common.
May be the result of fluid losses or decreased fluid intake.
Fluid losses may be haemorrhagic (int or ext) or non-haemorrhagic (int or ext).
Decreased fluid intake may be due to restricted water access or conditions where animals are unable to swallow/keep water down.

Question 5

What is cardiogenic shock?
Give examples.

Answer 5

‘Forward or ‘pump’ failure i.e. reduced cardiac output.
- Conditions with decreased systolic function e.g. dilate cardiomyopathy.
- Conditions with diastolic dysfunction e.g. Hypertrophic cardiomyopathy or pericardial tamponade.
- Bradyarrhythmias e.g. AV block
- Tachyarrhythmias e.g. ventricular tachycardia.

Question 6

Obstructive shock.
Causes.

Answer 6

Due to physical obstructions in blood flow to or from the heart or through the great vessels.
Overlaps with cardiogenic shock.
Causes
- GDV
- Pericardial tamponade
- Tension pneumothorax
- Pulmonary or aortic thromboembolism.

Question 7

Distributive shock.
Causes.

Answer 7

Shock due to maldistribution of blood flow, usually due to inappropriate and widespread vasodilation.
Causes:
- Histamine release i.e. anaphylaxis.
- Generalised uncontrolled inflammatory responses due to bacterial infection (sepsis) or non-infectious insults e.g. pancreatitis, trauma, burns etc.

Question 8

How is hypovolaemic shock further classified?
Give defs.

Answer 8

Compensated = the homeostatic mechs are successfully maintaining tissue perfusion.

Decompensated = Compensatory physiological mechs are are failing and the patient is in danger of dying.

Question 9

Give canine HR ranges for…
1. Normal
2. Mild shock (comp)
3. Moderate shock
4. Severe shock (decomp)

Answer 9

1. 60-120
2. 130-150
3. 150-170
4. 170-220

Question 10

Give canine MM colour ranges for….
1. Normal
2. Mild
3. Moderate
4. Severe

Answer 10

1. Pink
2. Normal to pinker
3. Pale pink
4. Pale pink to white

Question 11

Give canine CRT ranges for……
1. Normal
2. Mild
3. Moderate
4. Severe

Answer 11

1. <2
2. <1
3. 2
4. > 2

Question 12

Give canine pulse quality ranges for….
1. Normal
2. Mild
3. Moderate
4 Severe

Answer 12

1. Normal
2. Bounding
3. Weak
4. Very weak

Question 13

Give canine sys BP ranges for……
1. Normal
2. Mild
3. Moderate
4. Severe

Answer 13

1. > 90
2. > 90
3. > 90
4. <90

Question 14

Give canine mentation for….
1. Normal
2. Mild
3. Moderate
4. Severe

Answer 14

1. Normal
2. Normal
3. Normal-obtunded
   4 Obtunded

Question 15

Give canine lactate conc ranges for…
1. Norm
2. Mild
3. Moderate
4. Severe

Answer 15

1. 0.5-2.5
2. 3-5
3. 5-8
   4 >8

Question 16

1. Give eq HR ranges for normal, mild and severe
2. ” “ MM colour “ “
3. ” “ CRT “ “
4. ” “ pulse strength “ “
5. ” “ mentation “ “
6. ” “ lac conc “ “

Answer 16

1. 30-40, 44-60, >60
2. pink, pinker, pale
3. 1.5, <1, >2
4. easily palpable, bounding, weak
5. norm, norm, depressed
6. 0.5-2.5, 3-5, >8

Question 17

Initial treatment of HV shock?
What should the treatment also aim to do?
Potential treatment in severe blood loss?
First priority in HV shock patients?

Answer 17

Rapid administration of fluids to restore the intravascular volume and improve tissue perfusion.
Target the underlying cause.
Transfusion therapy.
Getting vascular access.

Question 17

Challenge of identifying hypovolaemic shock in the feline patient.
Common features of hypovolaemic shock in feline patients?

Answer 17

white coat effect – characterising pulse quality is challenging.
Do they decompensate more rapidly or present later?
Bradycardia and hypothermia.

Question 18

Stages of treatment of HV shock using isotonic crystalloids?

Answer 18

1. Bolus: administer 10-20ml/kg in dog and 5-10 ml/kg in cat over 15-20 mins. Monitor throughout.
2. Reassess for improvement.
3. Bolus: administer a further bolus as in step 1 if required. Monitor throughout.
4. Reassess the patient again – aiming for norm/near norm CV parameters.
5. If 45-60ml/kg administered in dog and 30-35ml/kg administered in cat with minimal improvement, consider if you have right dx. or is there ongoing blood loss?
6. If patient is losing blood and there is concurrent anaemia (PCV<20%) then consider administration of blood products.
7. Once patient stable, move on to maintenance fluid therapy.

Question 19

What does ‘shock dose’ mean?

Answer 19

Shock doses equate to the total blood volume of the patient.
80-90ml/kg in dog and 50-55ml/kg in cat.
Aim is not to administer the full shock dose.
Question dx or approach if full shock dose has been administered w/o good effect.

Question 20

Determining efficacy of treatment…
1.What is the goal of the treatment?
2. How often should a major body system assessment be carried out initially?
3. What parameters are included in the major body systems assessment?
4. What would lactate do with effective treatment?
5. Target for urine output?
6. Why would an ECG be taken?

Answer 20

1. For the patient to have normal or near normal CV parameters.
2. Every 15-30 mins.
3. Mentation, HR, pulse quality, RR, MM colour, CRT, temp etc.
4. Decrease.
5. > 0.5ml/kg/hr.
6. To monitor arrhythmias which may be responsible for the shock state or that may develop as a result of shock.

Question 21

1. What will hypertonic fluids do?
2. What does this do to the initial vol requirement for volume resus?
3. What do hypertonic fluids do to cerebral oedema?
4. How much hypertonic fluid administered?
5. What needs to be administered after the hypertonic fluids? – Why?
6. Where would hypertonic fluids be contraindicated?

Answer 21

1. Move water from the extravascular to the intravascular compartment.
2. Decreases it.
3. Reduce it.
4. 4ml/kg administered ONCE.
5. Isotonic crystalloids – replace the ‘debt’ to the extravascular compartment.
6. If the patient is hypernatraemic or dehydrated.

Question 22

What about cows and horses?

Answer 22

Administering enough, fast enough is v difficult.
Use hypertonic fluid and follow with large volumes of isotonic water – stomach tube, voluntary, IV.

Question 23

Why is it important to identify the type of shock?

Answer 23

Optimum stabilisation strategy varies with type of shock. Fluid therapy not indicated for all types of shock, and may be contraindicated for some types.

Question 24

Give.... 1. History 2. PE findings 3. Diagnostic tests .....for cardiogenic shock.

Answer 24

Hx: Signs associated with heart failure e.g dyspnoea, exercise intolerance or syncope PE: Heart murmurs, arrhythmias and gallop rhythms. Concurrent 'backwards' heart failure. Diagnostic tests: Echocardiography, blood cardiac biomarkers, ECG.

Question 25

Give... 1. Hx 2. PE findings 3. Diagnostic tests ...for Obstructive shock.

Answer 25

1. Hx: Associated with underlying cause e.g. GDV -- Non-productive retching. 2. PE: Dept on site/cause of obstruction -- Abdo distension (GDV) -- Absence of hindlimb pulses w/ aortic thromboembolism. -- Pericardial effusion -- muffled heart sounds. 3. Diagnostic tests dept upon suspected cause e.g. R lat abdo x ray for GDV.

Question 26

Give... 1. Hx 2. PE 3. Diagnostic tests ...for distributive shock.

Answer 26

1. Hx: Antigenic stimulation e.g. administration or ABX or septic focus e.g. pyometra. 2. In compensatory phase: red/purple mm Sluggish CRT Bounding pulses. 3. Dept upon suspected cause e.g. abdo ultrasound for pyo.

Question 27

1. Treatment principles for cardiogenic shock. 2. Treatment for... -- Poor sys function -- Clinically sig arrhythmias -- Congestive heart failure -- Electrolyte abnormalities

Answer 27

1. Fluid therapy contraindicated! Provide O2. 2. Therapy tailored to individual: -- Poor sys function -- inotropic drugs. -- Clinically sig arrhythmias -- anti-arrhythmic agents. -- Congestive heart failure -- Fluid drainage e.g. diuretics and thoracocentesis. -- Patients with electrolyte abnormalities (e.g. hyperkalaemia) -- correction.

Question 28

Treatment of obstructive shock.

Answer 28

Relieve obstruction -- E.g. GDV decompress -- E.g. pericardial tamponade -- pericardiocentesis. Some respond well to fluid therapy. -- E.g. GDV. Some not fluid responsive -- esp if underlying cardiac disease. -- E.g. pericardial tamponade and thrombotic disease (blood clots)

Question 29

Treatment of distributive shock.

Answer 29

Patient have relative hypovolaemia -- may be fluid responsive. Treat underlying cause. -- Sepsis -- ABX -- Anaphylaxis -- Anti-histamines May have leaky vessels -- avoid excessive crystalloid fluid therapy. Drugs which alter heart contractility (inotropes) and cause vasoconstriction (vasopressors) may be needed for some patients, but if used inappropriately, could cause more harm than good. Seek specialist advice first.