acute abdomen and shock

Question 1

what is shock? What is it due to in general terms?

Answer 1

Tissue Hypoxia (low oxygen), which can be due to:
* Reduced oxygen delivery to tissues
* Excessive oxygen demand/usage by tissues
* Inadequate utilisation of oxygen by tissues

Clinically, we usually care about the first of these (reduced delivery) and categorising which type is causing this.

Question 2

what is metabolic shock?

Answer 2

hypoglycemic shock (not enough glucose therefore can’t combine with oxygen to make energy)

Question 3

what is hypovolaemic shock?
what are the clinical signs?

Answer 3

volume loss and therefore inability of body to get enough blood round the body
* pale
* Slow CRT
* high HR (low in cats)
* low temp
* weak pluses
* incr RR

Question 4

what are the diagnostic markers for hypovolaemic shock?

Answer 4

Clinical signs and history plus:

Low blood pressure.

Elevated Lactate.

Point of care ultrasound:

Collapsing caudal vena cava (flat)
Poorly filling heart

Question 5

what is distributive shock?
What are the clinical signs?

Answer 5

(relavtive hypovolaemia) -
is a state of relative hypovolemia resulting from pathological redistribution of the absolute intravascular volume.

dilation of vessles

• red mm
• short/fast CRT
• high HR
• pyrexia
• boundign pulse
• Incr RR

Question 6

what are the causes of distributive shock?

Answer 6

Primarily as result of inappropriate vasodilation, however ‘leaky vessels’ also plays a role.

Sepsis/SIRS is probably the most common version you will see, the inflammatory cascade releasing pro-inflammatory cytokines that promote vasodilation and permeability.

Question 7

what is the diagnosis of distributive shock?

Answer 7

Clinical signs and history plus:

Low blood pressure.

Elevated Lactate.

Point of care ultrasound:
* Collapsing caudal vena cava (flat)
* Poorly filling heart
* Septic focus e.g. septic abdomen (free fluid)
* Evidence of vascular leak e.g. pulmonary oedema, small effusions.
* Gall bladder halo sign (oedema of the wall)

Question 8

what is the most common cause of systemic odema?

Answer 8

spesis - it causes leaking vessels and because it is a systemic disease it affects everywhere and therefore there is odema everywhere - distributive shock

Question 9

what is systolic pressure?

Answer 9

measure of ventricular (pump) function

Question 10

what is diastolic pressure?

Answer 10

the tone in the vessles (pipes)

Question 11

how do you treat distributive shock?

Answer 11

Treatment is focused on vascular tone and permeability, but also needs some volume support (there are more ‘pipes’ to fill now)

Volume support – fluid bolus

Vascular tone support – vasopressors such as noradrenaline or dopamine.

Permeability support – ensuring oncotic pressure is adequate:
* Check albumin levels
* If low, consider plasma transfusion
* Start feeding e.g. a feeding tube

Question 12

what are the two vasopressors used in shock?

Answer 12

noradrenaline,
dopamine - Probably less effective in cats

Question 13

what will an animal with both hypovolaemic and distributive shock present as?

Answer 13

tachycardia, bounding pluse, poor mentation,
normal CRT, mm, temperature

Question 14

what are the 4 types of shock?

Answer 14

volume:
- hypovolaemic (reduced volume)
- distributive (increased diametre or pipes)

output
- cardiogenic (failure of pump - electrical)
- obstructive (fluid around heart, thrombus)

Question 15

what is cardiogentic shock?
what are the clinical signs?

Answer 15

a disorder of cardiacfunction in the form of a critical reduction of theheart’s pumping capacity, caused by systolic ordiastolic dysfunction leading to a reduced ejectionfraction or impaired ventricular filling

can also be bradycardia, tachycardia

Clinical signs are associated with poor output and peripheral vasoconstriction:
* Pale
* slow CRT
* high HR/Low/arrhythmia
* low temp
* Pluses weak/ deficits
* RR high

Question 16

what is the diagnostics for cardiogenic shock?

Answer 16

Clinical signs and history plus:

Low systolic blood pressure (< 90mmHg SAP)

Elevated Lactate.

Point of care ultrasound:
* Poorly contracting heart
* Evidence of cardiac disease

ECG
* Brady-arrythmia e.g. atrial standstill or AV block with escape complexes
* Tachy-arrythmia e.g. ventricular tachycardia and evidence of output failure e.g. pulse deficits.

Bloods for electrolytes

Question 17

how does dobutamine work for cardiogenic shock?

Answer 17

Positive inotrope (Beta 1 agonist) makes heart pump harder, will increase myocardial oxygen demand. consider O2 support

Rapidly metabolised – constant rate infusion.

Commonly used in equine for cardiovascular support when anaesthetised.

Question 18

how does pimobendan work for cardiogenic shock?

Answer 18

Phosphodiesterase III inhibitor – increases intracellular calcium sensitivity – positive inotropy. puts more calcium into the muscles therefore causes the muscles to contract harder

Does not increase myocardial oxygen demand.

can also be given for heart disease that is sub clinical as will increase pressure and therefore slow progression

Question 19

what is obstructive shock?
what are the clinical signs?

Answer 19

Obstructive shock is a condition caused by the obstruction of the great vessels or the heart itself

• pale
• slow CRT
• high HR
• temp low
• pluse weak
• RR increased

Question 20

what are the causes of obstructive shock?

Answer 20

Lesser circulation:
- reduced filling of the right side of the heart - > e.g. Cardiac Tamponade (pericardial effusion severe enough to equal right filling pressures)
- increased workload for the right ventricle e.g. pulmonary thromboembolism, or mediastinal mass compressing pulmonary vasculature.

Greater circulation:
- impedance in a major vessel e.g. severe aortic stenosis.

Reduced preload – i.e. reduced venous return - > vena cava compression e.g. neoplasia, GDV or tension pneumothorax (air pressure in the thoracic cavity is equal to caval pressure preventing venous return)

The location of the obstruction is key to determining the clinical signs, regardless, they will all result in reduced diastolic filling and therefore reduced output signs like cardiogenic shock.

Question 21

what is the diagnosis of obstructive shock?

Answer 21

Clinical signs and history plus:

Elevated lactate

Point of care ultrasound:
* Loss of glide sign – tension pneumothorax
* Pericardial effusion and right sided collapse of ventricle and atria – cardiac tamponade
* Right ventricular enlargement – pulmonary hypertension – pulmonary thromboembolism
* CVC distension (downstream occlusion) or compression
* Aortic outflow obstruction
* Neoplasia

Question 22

what is the treatment for obstructive shock?

Answer 22

Relieve the obstruction if possible:
Cardiac tamponade – pericardiocentesis
Tension pneumothorax – thoracocentesis
GDV – gastric decompression

If immediate removal is not possible, supportive care:
PTE – platelet inhibitors (stops it getting worse and body will deal with it) and oxygen therapy
Neoplasia – force preload through a fluid bolus before surgery

Question 23

name two postive inotropes

Answer 23

Pimobendan
Dobutamine

Question 24

what is the acute abdomen?

Answer 24

acutely painful abdomen - collapse, vomiting, shock