PEMS

Question 1

What are the indications for one lung ventilation?

Answer 1

isolation of the lungs
improve surgical access
greater control over ventilation
unilateral bronchopulmonary lavage

Question 2

What is the aim of cardiac level protection against micro/macro shock?

Answer 2

Combined current leaking through heart <10microgA.

- Note 100microg A -> microshock

Question 3

What is the difference between RCD and LIM?

Answer 3

Residual current device - interruption of circuit if leak detected.

LIM - loss of supply doesn’t occur but alarms at low leakage to allow search and repair of faulty equipment

Question 4

What is the component of a RCD

Answer 4

toroidal transformer with neutral and active wires running through.

Generates magnetic field.

If different, interrupts circuit within 40msec

Question 5

For applied parts of equipment, what are the different levels of safety?

Answer 5

Type B unprotected - earthed, non-conductive, bed

Type BF body protected- high resistance device applied to patient to limit current, like BP cuff. Not safe for cardiac contact

Type CF - cardiac device, ensure that no more than 10microgA can be conducted.

Question 6

What happens if the LIM alarm goes off?

Answer 6

Identification of leakage possible through elimination.

Often the last piece of equipment plugged is usually the suspect and should be unplugged.

Send the faulty equipment for repair

Question 7

What are the mechanisms of action for methadone?

Answer 7

potent mu agonist
NMDA receptor antagonist
monoamine reuptake inhibitor

Question 8

Which form of methadone does the NMDA blockade?

Answer 8

R form

Question 9

How much does BMR increase during exercise?

Answer 9

10-20 folds

Question 10

Why does BMR increase after food?

Answer 10

Protein > fat/carb

energy cost for assimilating food into body

Question 11

How much does BMR decrease with age?

Answer 11

highest in neonates and children.

Decreases with age at roughly 2% per decade

Question 12

Time frame of measuring BMR?

Answer 12

the metabolic rate within the thermoneutral zone 12-14 hours after a meal

Question 13

In relation to hypothermia, what is Hunting Reaction?

Answer 13

Paradoxical vasodilation with prolonged cooling, prevents frostbite.
- Direct cold induced paralysis, rending the vessels unresponsive to catecholamines

Question 14

What are the solvents used as additives?

Answer 14

Water (vec) - causes hydrolysis of drugs, easily contaminated

Propylene glycol (digoxin) - can cause acidosis (increased lactic acid), thrombophebitis, pain on injection

Benzyl alcohol (cyclazine, hydrocortisone) - hypotension by peripheral VD and myocardial depression, dermatitis, sensitisation

Question 15

What are the potential problems associated with propofol soybean emulsion?

Answer 15

pain on injection
Incompatibility with many drugs
supports bacterial growth
high manufacturing cost

Question 16

Give an example of anti-oxidant additive

Answer 16

sulphites in adrenaline

causes hypersensitivity reactions

Question 17

Give examples and issues related to preservatives

Answer 17

Benzalkanium chloride - used in bronchodilators, can cause bronchoconstriction

Chlorbutol in ophthalmic preparations, can cause sedation

Parabens - prevents fungal growth, can reduce cAMP in chronic use

Question 18

What is an isomer?

Answer 18

molecules with the same atomic formulae but different structural arrangements

Question 19

What are the types of isomers?

Answer 19

Structural - different order of atomic bonds

Tautomerism - dynamic interchange between isomers by change of physical environment

Stereoisomerism - same bond structure but different spatial configuration

Question 20

What are the different types of stereoisomers

Answer 20

Optical: appears to be mirror image of each other with at least one chiral centre 
(
Enantiomer, 1 chiral centre 
Diastereoisomer, >1 chiral centre 
) 

Geometric - same chemical constituents and same covalent bonds but with different spacial orientation

Question 21

What are the different ways to classify enantiomers?

Answer 21

negative left handed sinister bitch
Negative = levo = sinister

By direction of rotation to polarised light

• Dextro, right
• Levo, left

By absolute configuration of 4 functional groups attached to chiral centre

• Sinister, anticlockwise descending atomic number
• Rectus, clockwise

Question 22

Chemo drugs mnemonic - A dapper man had many tuxedos.

What are the drugs? Side effects?

Answer 22

Antimetabolites - methotrexate (hepatitis, pulmonary toxicity, cystitis), doxorubicin (cardiotoxicity)
DNA binding - bleomycin (pulmonary), cisplatin (ototoxic / nephrotoxic)
Microtubules - vincristine (peripheral neuropathy)
Hormones - tamoxifen (hot flushes, VTE)
Monoclonal - rituximab (allergy/anaphylaxis)
Tyrosine kinase antagonist (Long QTc, metastatic potential)

Question 23

How effective is NAC infusion for paracetamol overdose?

Answer 23

Complete protection if given <8 hrs

Incomplete protection but reduce mortality >8hrs

Question 24

What is the dose of NAC infusion?

Answer 24

loading dose 150mg /kg over 1/24
then 50mg /kg over 4/24
then 100mg / kg over 16/24

Question 25

For disease with low incidence, how high does the likelihood ratio need to be for the a test to be useful?

Answer 25

> 10

+ve likelihood ratio = sensitivity / ( 1-specificity )