Ch6 Neurocritical care

Question 1

What is the action of Nicardipine?

Answer 1

Ca channel blocker

Question 2

What is the action of Labetalol

Answer 2

alpha-1 selective and beta non-selective blocker

Question 3

What is the effect of Labetalol on cardiac output?

Answer 3

No change

Question 4

What is Enalaprilat?

Answer 4

The active metabolite of Enalapril (ACE-inhibitor)

Question 5

What is the action of Esmolol?

Answer 5

Short acting beta-blocker

Question 6

What is the action of phenylephrine?

Answer 6

Alpha sympathomimetic. Elevates BP by vasoconstriction. Lack of beta-adr action means no cardiac side effects.

Question 7

What is the risk of PPI in critically ill patients?

Answer 7

Reduces ulceration but the higher pH causes gastric colonisation and increased incidence of pneumonia (from aspiration)

Question 8

What is the action of PPIs?

Answer 8

Block H+/K+ ATPase on the surface of parietal cells in the stomach

Question 9

What interaction does omeprazole have on warfarin / phenytoin?

Answer 9

Cytochrome P450 inhibition causing impaired clearance of warfarin and phenytoin

Question 10

What is rhabdomyolysis?

Answer 10

Damage to skeletal muscle causing leakage of myoglobin that is toxic to the renal tubules

Question 11

What is the triad of rhabdomyolysis?

Answer 11

Muscle weakness, myalgia and dark urine

Question 12

What is the management of rhabdomyolysis?

Answer 12

ABC, catheter, correct electrolyte abnormalities, IV fluids, bicarbonate +/- mannitol. Dialysis if oliguric

Question 13

What are the different types of cerebral oedema?

Answer 13

Cytotoxic - due to Na/K pump failure from ischaemia Vasogenic - increased vascular permeability from tumour, infection etc Hydrostatic - due to increased cerebral capillary pressures such as in malignant hyperthermia Interstitial oedema - Transependymal CSF flow in hydrocephalus Osmotic - due to reduced plasma osmolality which is seen with SIADH, dialysis and water intoxication

Question 14

What is the effect of dexamethasone on cerebral oedema?

Answer 14

Reduces oedema by inhibiting VEGF and restoring the BBB. Time to maximal concentration in brain 3-4 hours. Half-life 56 hours. Metabolised in the liver and renally excreted.

Question 15

What is propofol infusion syndrome?

Answer 15

Bradycardia and metabolic acidosis / rhabdomyolysis / hyperlipidaemia.Due to mitochondrial respiration inhibition. ECG shows RBB with ST elevation.

Question 16

What is red man syndrome?

Answer 16

Pruritis, urticaria, angioedema, tachycardia, hypotension and maculopapular rash. Related to vancomycin. Histamine mediated response.

Question 17

What is the treatment for drug induced dystonic reactions?

Answer 17

Procyclidine

Question 18

What are the complications of phenytoin loading?

Answer 18

Bradycardia and heart-block. Elderly patients with multiple large doses of phenytoin may suffer from purple glove syndrome (swollen, discoloured and painful extremities)

Question 19

What are the dose equivalents of Dexamethasone, Methylpred, Prednisolone and Hydrocortisone?

Answer 19

0.75mg : 4mg : 5mg : 20 mg

Question 20

How long does Dexamethasone action last?

Answer 20

56 hours

Question 21

How long does prednisolone / methylprednisolone action last?

Answer 21

12-36 hours

Question 22

How long does hydrocortisone action last?

Answer 22

8-12 hours

Question 23

What are the side effects of thiopentone?

Answer 23

Immunosuppression, hypokalaemia (due to intracellular sequestration) causing rebound hyperkalaemia and hypertension after it is stopped.

Question 24

What are the peaks in the ICP waveform?

Answer 24

1 = percussion (ejection of blood from the heart) 2 = tidal (brain compliance) 3 = dicrotic (closure of the aortic valve) In normal conditions the 1>2>3. With raised ICP and loss of cerebral compliance 1=2=3.

Question 25

How does CBF change with PaO2 and PCO2?

Answer 25

Question 26

How much cardiac output goes to the brain?

Answer 26

Brain weighs 1.4 kg. It receives 15% of CO It uses 20% of the oxygen It uses 25% of the glucose

Question 27

What is the metabolic requirement for oxygen of the brain?

Answer 27

50 ml 02/min (Based on oxygen content of 20ml per 100ml of blood and CBF of 50ml/100g/min the delivery is 150 ml O2/min so only 1/3 is extracted = oxygen extraction fraction)

Question 28

At what CBF do EEG slowing occur?

Answer 28

\<23 ml/100g/min. When \<10 ml/100g/min there is irreversible damage and this is the core. The surrounding area with CBF 10-17 ml/100g/min forms the penumbra.

Question 29

What is the evidence for hypothermia as cerebral protection in aneurysm surgery?

Answer 29

IHAST2 compared WFNS1-3 aneurysm clipping with hypothermia 33 deg compared to normothermia 36.5 deg. No difference in outocme!

Question 30

Summarise the eurotherm trial

Answer 30

TBI within 10 days that have ICP monitor and failure of tier 1 ICP management (I&V, sedated, head up etc) Randomised to between 32-35 deg as per ICP via cold saline boluses Odds of unfavourable outcome and death @ 6 months with cooling so trial discontinued (Hypothermia for intracranial hypertension after traumatic brain injury. N Engl J Med 2015)

Question 31

What is the Bohr effect?

Answer 31

Shift of the oxygen dissociation curve to the right caused by increase in temperature, hypoxia and hypercapnia

Question 32

What is the classification of haemorrhagic shock?

Answer 32

Question 33

Above which level does spinal shock cause neurogenic bradycardia?

Answer 33

Above T5

Question 34

What is the definition of ARDS?

Answer 34

Pa02/Fi02 ratio \<200 (\<26 kPa) is the absence of cardiac failure

Question 35

What is a normal PaO2?

Answer 35

11-13 kPa = 80-100 mmHg

Question 36

What is a normal PaCO2?

Answer 36

4.5-6 kPa = 35-45 mmHg

Question 37

What is a normal HC03-?

Answer 37

22-26 mEq/L

Question 38

What is a normal BE?

Answer 38

-2 to 2

Question 39

Why does alkalosis cause perioral tingling?

Answer 39

As the pH rises the concentration of ionized Ca decreases (more binds to albumin) which causes perioral tingling