SHOCK

Question 1

INDIRECT MEASUREMENTS OF PERFUSION

Answer 1

BLOOD pressure
consciousness - brain perfusion
urine output - renal perfusion
lactate - general tissue perfusion

Question 2

how can Mean arterial pressure be calculated (MAP)

Answer 2

cardiac output (CO) X Systemic Vascular Resistance (SVR)

Question 3

classifying shock

Answer 3

cardiogenic - pump issue
distributive - pipe problem
–> commonest, septic

hypovolaemic - filling problem
obstructive - blockage

Question 4

hypovolaemic shock

Answer 4

acute haemrrhage
fluid depleted states - severe dehydration, burns

volume depletion leads to reduced SVR
- reduced volume returning to heart - (compensatory vasoconstriction) reduced pre-load + hence reduced CO

Question 5

cardiogenic shock

Answer 5

“pump failure” - reduced CO
- reduced contractility -> reduced stroke volume

unless correctable pathology (valvular) - mortlity >75%

Question 6

types of distributive shock

Answer 6

septic
anaphylaxis
neurogenic

Question 7

obstructive shock

Answer 7

Mechanical obstruction to normal cardiac output in an otherwise normal heart

Direct obstruction to cardiac output
o PE
o Air/fat/amniotic fluid embolism

Restriction of cardiac fillung
o Tamponade
o Tension pneumothorax

Question 8

gold standard monitoring of cardiac output

Answer 8

thermodulution with a PA catheter
- rarely used outside of specialised units

phase focus: salvage, optimisation, stabilisation, de-escalation

Question 9

target MAP in treatment of shock

Answer 9

65-75mmHg

but relative to clinical picture
 Hypertensive patients
 Ongoing haemorrhage

Question 10

choice of fluids

Answer 10

Crystalloids
o Convenient, cheap, safe
o Rapidly lost from circulation to extravascular spaces, significantly larger volumes needed

Colloids
o Cheap ish, reduce volumes requires
 Can cause anaphylaxis, no evidence of benefit (Can cause harm)

Blood
o Oxygen carrying capacity, will stay in circulation
o Scarce resource, risks (immunogenic)

Question 11

next line treatment when fluids don’t/stop working

Answer 11

need admit in critical care environment
vasopressors
- noradrenaline
- adrenaline
- vasopressin

Question 12

de-esclation in hypovolaemic shock

Answer 12

• Remove extra fluid once shock has resolved
• Mortality benefit in getting patients “dry” as early as possible
• Various means – spontaneous, diuretic, dialysis

Question 13

side effect of fluid resus

Answer 13

Ass with significant fluid admin + positive balance

Volume delivered never remains intravascular
o Extravascular overload in a intravascular “dry” patient
o Subcutaneous oedema obviously
 Others – “wet” lungs/ARDS, bowel oedema, brain

Question 14

reversible causes of shock

Answer 14

4Hs + 4Ts
hypoxia
hypovolaemia
hypo/hyperkalaemia
hypothermia

thrombosis
tamponade
tension pnuemothoraw
toxins

Question 15

causes of obstructive shock

Answer 15

massive PE
cardiac tamponade
tension pneumothorax - pressure creates kink in aorta/vena cava
constrictive pericarditis
aortic stenosis
abdominal compartment syndrome

(recent thoracotomy, chest wall trauma, evidence of DVT)

Question 16

management of obstructive shock

Answer 16

relieve obstructions
- thrombolysis / thrombectomy
- pericardiocentesis

Question 17

distributive shock

Answer 17

umbrella term (septic, anaphylactic + neurogenic) where uncontrolled vasodilation overcomes the compensatory mechanism od increased CO
-> blood going but to wrong place

• Due to disruption of normal vascular autoregulation + profound vasodilatation
• Poor perfusion – despite increased cardiac output
• Regional perfusion differences
• Alteration of oxygen extraction

Question 18

neurogenic shock

Answer 18

(NOT spinal)
loss of sympathetic nervous system tone
cord injury above T6 (below unlikely to get neurogenic shock) leading to lack of feedback
- sympathetic all way down spine, para just at top

bradycardia (uncontrolled vagal tone)

Question 19

Mx hypovolaemic shock

Answer 19

Fluid and blood replacement
* DON’T give dextrose unless hypoglycaemic
* High flow o2

Stop the losses
* Haemorrhage control
* Treat the diarhoea
* Wrap the burns

Question 20

Mx of cardiogenic shock

Answer 20

Careful fluid management, inotropes (eg. Dobutamine) vasopressors (eg noradrenaline) and treatment of the underlying cause eg PCI

Underlying cause
* PCI, thrombolysis thrombolysis if >2hrs
* Antiarrhythmias
Supportive measures
* Inotropes - increase contractility (how hard heart pumps)
* Vassopressors - vasoconstriction
* Mechanical
o Balloon pumps
o Ventricular assist devices

Cautious with fluids

Question 21

mx of neurogenic shock

Answer 21

vasopressors