MOD 2 RESP MED

Question 1

Brain ischaemia metabolic changes?

Answer 1

Brain ischaemia leads to acidosis, decreased protein synthesis and increased glutamate release
Glutamate release –> Na & Ca2+ entry into neurones, water follows via osmosis
Cell swells and eventually bursts
In addition, free radicals generated through membrane degradation leads to further DNA damage and apoptosis

Question 2

Neuroprotective effects of anaesthetic agents

Answer 2

Rapidly cross BBB
Decreased cerebral metabolic rate
Allows patient to tolerate hypothermia
Anti-excitotic

Question 3

Xenon neuroprotective effects

Answer 3

NMDA antagonism
Non-toxic, anti-apoptotic, anti-excitotic
Up-regulates p-CREB - TF in neuroprotection
Xenon + hypothermia –> reduced expression of pro-apoptotic mediators

Question 4

Hypothermia effects

Answer 4

Improves 6 month survival following VF arrest (<35 deg)
Reduces glutamate release –> reduced ROS
Reduced apoptosis
Reduced cerebral metabolic rate

Question 5

What contributes to minimal residual disease in cancer surgery?

Answer 5

Handling of tumour during surgery --> release of CTCs into circulation
CTCs in circulation --> poorer outcomes
Clinically undetectable micrometastases
Incomplete resection
These CTCs either:
- Die
- Lie quiescent
- Re-establish as metastases

Question 6

Similarities between innate inflammatory response and tumour microenvironment

Answer 6

ECM remodelling
Angiogenesis
Local mediators e.g. PGE2 (prostacyclin)
Endothelial activation
Trophic signalling --> initiates repair mechanisms
Immune cell recruitment
Cytokine amplification
Sympathetic NS activation

Question 7

Neuraxial blockade significance in surgical stress response

Answer 7

Has the ability to attenuate the surgical stress response by blocking nociceptive signalling to the brain
-Intraoperative epidural reduces catecholamine and cortisol release and improves blood leukocyte and NK cell numbers
Also improves cytotoxic NK function

Question 8

Cardiovascular effects of BSD

Answer 8

During the coning process: Massive catecholamine release - ‘autonomic storm’
–> pulmonary microvascular damage and irreversible PO (neurogenic pulmonary oedema)

Then…

Vasoplegia - loss of sympathetic tone, fall in catecholamine levels

Following brain death - SIRS type response - pro inflamm cytokine release

Question 9

Pulmonary shunt

Answer 9

When there is a V/Q mismatch - part of the lung is perfused but not ventilated
–> hypoxaemia