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royal college questions > ELFH exam course section questions > Flashcards

ELFH exam course section questions Flashcards

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Royal College: Emergency Medicine flashcards
1
Q

How will the deflection appear on an ecg if the impulse is travelling away from the electrode?

A

negative deflection

(positive for towards)

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2
Q

what is the lead position for the chest leads on an ECG?

A

V1 = 4th intercostal right of sternum
V2 = 4th intercostal left of sternum
V4 = 5th intercostal mid clav line
V6 = 5th intercostal mid axillary line

V3 and V5 inbetween

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3
Q

what are the 3 lead types on an ECG?

A

limb leads - bipolar = lead 1 , 2, 3
limb leads - augmented/ unipolar = aVF, aVL, aVR
chest leads = precordal - view in horizontal plane

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4
Q

what is the normal cardiac axis?

A

-30 degrees to + 90 degrees

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5
Q

what is left axis deviation and right axis deviation as an angle?

A

>

  • 90= RAD
    -30 = LAD
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6
Q

what is the standard calibration for an ecg?

A

1mV / cm
25mm/s

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7
Q

what is seen in ecg for posterior ischaemia?

A

ST depression V1-V4
R>S in V1 and V2
upright T in V1 and V2

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8
Q

how is CM5 electrodes set up ? what is this mostly for?

A

red = manubrum
yellow = V5 position
green = neutral = anywhere but usually left clavicle

good for viewing left ventricle and diagnosing ischaemia

CM5 = clavicle manubrum V5

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9
Q

how is PR interval measured?

A

start of P to start of QRS
should be <0.2ms (5 small squares)

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10
Q

what are the 2 most common valvular lesions?

A

Mitral regurgitation
aortic stenosis

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11
Q

what happens to EDV and ESV in mitral regurgitation?

A

eventually dilation of heart and both of these volumes are increased

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12
Q

what murmur is heart in mitral regurgitation?

A

pan systolic
max at apex of heart
3rd heart sound sometimes

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13
Q

what ecg changes are seen in mitral regurgitation?

A

p mitrale
AF
LVH

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14
Q

how should you tailor your anaesthetic for mitral regurgitation?

A

Avoid bradycardia - increases the time for regurgitation

minimize vasoconstriction - to achieve good forward flow, a dilated peripheral circulation is required

Avoid a large increase in preload, because this can decompensate the heart

MR likes ‘Fast and Loose!’

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15
Q

how is compliance of heart affected in aortic stenosis? what else happens

A

narrowered valve, increased LV pressure, LVH

hypertrophy reduces compliance
this limits passive filling of the heart

now atrial systole has more significance

Myocardial O2 consumption increased

reduces blood flow through the coronary arteries because transmitted LV diastolic pressure acts as a Starling resistor and reduces the coronary perfusion gradient. The subendocardium is particularly vulnerable to ischaemia

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16
Q

what murmur is heard in aortic stenosis?

A

harsh ejection systolic

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17
Q

what are the ecg changes associated with LVH?

A

The voltage criteria are met if an R wave in either lead V5 or V6 exceeds 25 mm or if the sum of the tallest R wave (in V5 or V6) with the deepest S wave (in V1 or V2) exceed 35 mm

Left axis deviation

T wave inversion (in V5 or V6) with or without ST depression indicates a ‘strain’ pattern

prolonged QRS is another feature

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18
Q

what is the area of a normal aortic valve?

A

2.5 to 3.5 cm3

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19
Q

how can aortic stenosis be graded?

A

clinical severity

ECHO
- cross sectional area
- gradient

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20
Q

how is severe and critical aortic stenoiss classified ?

A

severe = gradient >40mmHg , aortic area <1cm3

critical = gradient >80mmHg, aortic area <0.5cm3

valve area is a more useful indicator, gradient may not always be high.

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21
Q

how would you manage someone anaesthetically with aortic stenosis?

A

slow and tight

slow HR - less demand ,tachycardia will reduce diastolic time and coronary flow.

preserve SVR - to preserve gradient for coronary filling (the inflow pressure for coronary perfusion in diastole is the aortic diastolic pressure). also maintains preload.

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22
Q

when are J waves on an ecg seen?

A

hypothermia
hypercalcaemia
massive head injury and sub-arachnoid haemorrhage.

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23
Q

what degrees are lead 1, 2, 3 on the axis?

A

Lead II is at 60°, Lead I is termed 0° and Lead III at +120°.

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24
Q

what is the regurgitant fraction in mitral regurgitation?

A

the ratio of the flow that leaves the left ventricle and enters the left atrium versus that which enters the aorta.

A ratio of 0.3 indicates mild regurgitation and 0.6 indicates severe pathology.

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25
Q

describe what happens from sitting to standing…

A

gravity - sudden pooling of blood in capacitance vessels

drop of preload,
drop in SV

CO and BP fall

detected by barorecptors - increase in sympathetic tone

vasoconstriction, increase HR, increase conttractility

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26
Q

what are the classes of haemorrhage?

A

class I to IV

class I = 15% blood loss. not many clinical signs - anxiety maybe

class II = 15 to 30%. tachycardia, tachypnoea, urine output <0.5ml/kg/hr. narrow pulse pressure

class III = 30-40% = same as above but more marked. now drop in BP , may get confusion etc

class IV >40%
weak pulse, anuria, reduced consciousness

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27
Q

how does the body respond to blood loss?

A

vasoconstriction e.g. to kidney and guts

sympathetic stimulation to aid this and improve CO

fluid translocation from interstitium = 0.25ml/kg/min (due to drop in hydrostatic pressure via starling)

RAAS - due to reduced renal perfusion
↑angiotensin II (potent vasoconstrictor)
↑aldosterone (renal retention of Na)
Anti-diuretic hormone (ADH) - thirst, water conservation and vasoconstriction

later
- EPO and reticulocytosis
- plasma protein synthesis

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28
Q

how much of normal saline stays intravascular?

A

750 mls traverse into the ISF
250 mls remain in IVF.

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29
Q

how much 5% glucose goes into the intravascular compartment?

A

2/3 enters the intracellular fluid compartment

1/3 remains in the extra cellular compartment, of which
ISF (75%)
IVF (25%)

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30
Q

what is valsalva?

A

forced expiration against closed glottis

increases intrathoracic pressure by 40mmHg

illustrates autonomic control of both HR and BP

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31
Q

what are the phases of valsalva?

A

phase 1
Squeeze on intra-pulmonary vessels
Return of more blood to left atrium
Increased preload results in increased SV
Direct transmission of intra-thoracic pressure onto aorta

phase 2
Continued strain leads to:
Impaired return of blood entering thorax
Reduced CO and BP
Baroreceptors sense reduced BP
Sympathetic compensation increases HR and peripheral vasoconstriction
(overall fall in BP, compensated for by rise in HR)

phase 3
Release of strain leads to:
Loss of squeeze on intra-pulmonary vessels. This temporarily reduces return of blood to heart, BP falls further
Too brief an interval for HR changes

phase 4:
Venous return to left atrium normalizes
CO now delivered onto a highly vasoconstricted peripheral circulation (from Phase II)
Overshoot of BP sensed by carotid sinus baroreceptors
Reflex vagal slowing of heart rate

look up graph - valsalva phases for HR and BP

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32
Q

what are the uses of valsalva?

A

test autonomic function
hear murmurs
stop SVT
unblock ears

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33
Q

what is the valsalva ratio?

A

max HR in phase 2 / max HR in phase 4

(can also use RR interval rather than HR)

A ratio of >1.5 indicates competent functioning of the autonomic cardiac control.

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34
Q

what would you expect age to do to the valsalva ratio?

A

reduced
age blunts baroreceptor response.

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35
Q

what would an alpha and beta blocker do to the phases of valsalva?

A

alpha blocker - in phase 2, there will be less compensation of vasoconstriction by the baroreceptor reflex. hence HR will have to compensate more = this leads to increased HR in phase 2. in phase 4 because of the lag time, there will be an increased over shoot in BP (due to increase in HR)

B blocker - less HR response in phase 2 so lower HR. hence in phase 4, the BP overshoot will be less because less effected by HR and lag.

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36
Q

how much fluid translocates from interstial fluid to IVF in shock?

A

0.25ml/kg/min

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37
Q

what are sympathetic pre and post ganglionic fibres?

A

pre - myelinated B fibres, short, release Ach (nACh)

post - unmyelinated , long, release NA

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38
Q

what receptors and NT do blood vessels within skeletal muscle recieve?

A

typically have post-ganglionic sympathetic cholinergic transmission (on to muscarinic receptors)

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39
Q

what do renal vessels sympathetic fibres release

A

and some renal vessels have dopaminergic transmission (D1 receptors).

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40
Q

how can valsalva be used for diagnosis of HOCM?

A

Almost all cardiac murmurs decrease in intensity during a Valsalva manoeuvre;

apart from the murmurs associated with mitral valve prolapse and hypertrophic cardiomyopathy.

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41
Q

what happens to blood volume in lungs and liver from lying to standing?

A

DROPS
The lungs and liver both act as reservoirs of circulating volume. When a change in posture or haemorrhage occurs then sympathetic stimulation triggers venoconstriction which mobilizes blood in these areas into the effective circulating volume

Venoconstriction not vasoconstriction

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42
Q

where are volureceptors located?

A

Volureceptors are located in the right atrium and great veins.

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43
Q

what is the threshold for osmoreceptor activation?

A

1-2 %

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44
Q

does a transfusion of 1L 0.9% saline trigger volureceptor activation?

A

no, they are only triggered by 8-10% change

0.9% saline add 250ml which is not enough

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45
Q

when is aortic blood flow lowest in cardiac cycle?

A

early diastole

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46
Q

when is aortic pressure highest?

A

mid systole

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47
Q

how much does atrial contraction contribute to ventricular filling

A

normal HR - 20%
tachycardia - 40%

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48
Q

how does the QRS relate to systole?

A

The QRS complex occurs immediately before isovolumetric contraction.

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49
Q

how to baroreceptors respond to low BP

A

reduced discharge

(increased discharge when stretched)

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50
Q

what pancreatic hormone is increased in acute haemorrhage?

A

glucagon
- increases with sympathetic output

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51
Q

how much does PVR fall at birth in a fetus?

A

by more than 80%

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52
Q

how long for the ductus arteriosus to close?

A

48 hours

(similarly FO takes atleast 48 hrs)

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53
Q

how does arteriolar and venous constriction affect starling forces?

A

arteriolar vasoconstriction - less flow through capillary bed , less fluid into interstitial space

venous = back flow so increases fluid out

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54
Q

what does the a wave correspond to on JVP? what causes an increase and decrease in this?

A

atrial contaction
increase = cannon a = tricispid stenosis, complete HB or junctional rhythms

reduced in AF

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55
Q

what change does tricuspid regurgitation cause on JVP?

A

v wave is larger
v wave is caused by atrial filling during ventricular systole.

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56
Q

how does perfusion of right and left coronary artery differ?

A

Unlike the left ventricle, the right ventricle receives most perfusion during systole due to its lower wall pressures.

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57
Q

which major organ has a high A-v O2 difference / O2 extraction?

A

cardiac

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58
Q

what is the preferential route from right to left ventricle for wave of depolarisation to take?

A

bachmanns bundle
a.k.a anterior interatrial band.

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59
Q

how does hypovolaemia affect valsalva?

A

reduced arterial presure in phase 2 is more exagerated

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60
Q

how is valsalva different in those with neuropathy?

A

less HR drop in phase 4
e.g. 20% of diabetic s

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61
Q

how does valsalva affect murmur of AS?

A

most murmurs decrease in intensity with valsalva

except MR and HOCM - increase

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62
Q

what is the max wavelength absorbed by oxy and deoxy Hb?

A

oxy = 940nm
deoxy = 660nm

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63
Q

what sats does methamohaemaglobin and carboxyHb read?

A

methaemo = 85%
carboxy = high sats

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64
Q

can fetal Hb alter saturation accuracy of pulse oximeter?

A

no

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65
Q

how much is the pulsatile component of the waveform in pulse oximetry?

A

2 %

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66
Q

what is the functional saturation?

A

Functional saturation is the ratio of O2HB to (O2Hb + reduced Hb)

includes other Hbs

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67
Q

in pulse oximetry what do motion artifacts do?

A

increase high ac to dc signal ratio

Motion will produce an increase in a.c. components however this is noise and therefore the signal to noise ratio will be lower

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68
Q

can external lighting effect the accuracy of pulse oximetry?

A

Yes
although partly accounted for by only including pulsatile portion

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69
Q

which O2 analysing electrode requires a battery?

A

CLARK

‘fuel already has fuel’

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70
Q

what is an example of a polarographic electrode?

A

clark

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71
Q

what gas can affect accuracy of the fuel cell?

A

N20

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72
Q

which has faster response time - polarographic or paramagnetic

A

paramagnetic

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73
Q

what type of analyser is used in most blood gas analaysers for oxygen?

A

polarographic - clark

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74
Q

how does a co-oximeter work?

A

A CO-oximeter measures the concentrations of different haemoglobins and calculates the oxygen saturation from the relevant percentages

INDIRECT.

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75
Q

what is measured DIRECTLY by blood gas analyser?

A

H+
PaO2

these in turn can give
pH
CO2 - sauvinghaus

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76
Q

without temp compensation in a blood gas machine what will hypothermic patients read as their PaO2?

A

high PaO2 reading

in hypothermic patient - they will be able to carry more O2 for a specific partial pressure OR at a specific O2 their PP will be lower.

hence now heat the sample, more O2 will leave - higher Pp

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77
Q

how do air bubbles in a blood gas affect PaCO2?

A

lowers it
air will have less CO2

78
Q

what happens if the blood is left at room temperature before a blood gas analysis?

A

cells metabolise O2 - lowers PaO2
increased CO2 –> lowers pH

79
Q

what happens if heparin is left in sample before blood gas analysis?

A

lower pH - heparin is acidic

80
Q

for oxygen analysis in a blood gas analyser, what is the electrodes and solution normally consist of?

A

anode is typically silver
cathode platinum
electrolyte solution is a potassium chloride solution

this is a clark electrode - seen in blood gas analysers

(A fuel cell contain a lead anode and gold mesh cathode - not usually in a blood gas analyser)

81
Q

what is faster the clark or fuel cells?

A

Clark - polarographic

(think clark is battery driven so likely to be faster)

82
Q

what is the main method for analysing anaesthetic gases? what other methods are there?

A

Infrared Absorption Spectrophotometry.

others - Photoacoustic spectrometry, Raman scattering, mass spectrometry and UV absorption

83
Q

which gases have absorption spectrum similar to CO2 and can interfere with infrared absorption spectrophotometry ?

A

Water vapour, sevoflurane and nitrous oxide

= collision broadening

84
Q

what wavelength of Infrared is used for CO2 absorption spectrophotometry?

A

4.3um

85
Q

what is the isobestic point?

A

point of equal absorption of both OxyHb and deoxyHb = 805nm
and 580nm

86
Q

what are refractometers?

A

typically used to measure vapour concentrations in gas mixtures by measuring the bending of light waves due to the change in gas composition.

They are used to calibrate vaporisers and measure vapour concentration INDIRECTLY

they themselves require calibration against known concs

87
Q

define base excess

A

The base excess is the amount of strong acid required to return the pH of 1 litre of blood to 7.40 at a PCO2 of 5.3 kPa and 37°C

88
Q

what is the range of wavelengths for visible light?

A

400 (blue) -700 (red) nanometers

89
Q

what is the absorption spectra for most volatiles in infrared absorption spectroscopy?

A

volatile agents peaks close to 3.3 micrometres

(CO2 = 4.3um)

90
Q

what is collision broadening?

A

when other gases are present, the collisions between gases alter the energy / wavelength each gas can absorb at that moment in time hence rather than a sharp absorption at one particular wavelength, there is a broader range.

e.g. CO2 alone - 4.3um
when in a mix with sevo, water and nitrous these gases also absorb some of this wavelenth and collide with CO2 so it absorbs other wavelengths

Collision broadening widens the range of wavelengths absorbed by CO2

91
Q

what pressure does a mass spectrometer work at?

A

vacuum

92
Q

how many electromagnetics in a mass spectrometer?

A

4

93
Q

how are ions accelarated in mas spectrometry?

A

by the cathode plate

94
Q

how are natural resonance and mass related?

A

natural resonance is inversely proportional to square root of mass

95
Q

define fouriers transformation?

A

Fourier Transformation is a mathematical operation that deconstructs a complex signal (wave) into its constituent frequencies (vectors)

96
Q

does blinding of a study reduce confounding variables?

A

no reduces bias

97
Q

what can a control group recieve?

A

placebo
standard treatment
historical treatment

98
Q

what is meant by intention to treat?

A

Intention to treat analyses data based on the initial treatment intended, rather than the treatment eventually given (eg if a patient dropped out of a study).

99
Q

what is the relative and absolute risk reduction?

A

incidence of an event before and after

absolute risk reduction = after - before

relative risk reduction = ARR / before

e.g. sore throat incidence is reduced from 20% to 15% in group given a treatemtn

RRR = 5%
ARR = 5/20= 25%

100
Q

can the power of a study depend on the statistical test used?

A

yes

can be used for both parametric and non-parametric

101
Q

for normal distributed data what statisitical tests are used?

A

normally parametric
(can also use non-parametric)

for non-normal can only use non-parametric

102
Q

what measure of central tendency is used in non normal distribution data?

A

MEDIAN

103
Q

how is central tendancy measured in categorical data?

A

mode

104
Q

what does a correlation coefficient of near 1 mean? i.e. r=1

A

association between 2 variables

it DOES NOT mean if one rises, the other rises

105
Q

can correlation coefficient be used for both parameteric and non-parametric?

A

yes

106
Q

what is the difference betweeen odds ratio and risk ratio?

A

Odds ratio is a ratio of two odds, while risk ratio is a ratio of two probabilities.

e.g.
risk ratio = probabilty of outcome in test group / probability of outcome in control group

odds ratio = odds of it occuring in test/ odds of it occuring in control

risk ratios are more intuitive

both measures of association

107
Q

what is the formula for standard error of mean?

A

Standard error of the mean is the Standard Deviation divided by the square root of (n - 1)

108
Q

is spearmans rank a parametric test?

A

no

109
Q

what is eulers number?

A

base of natural logarithm
2.718

110
Q

what type of graph would denitrogenation during induction give if plotted with time?

A

negative exponential i.e. wash out

if plot log N2 against time = straight line

111
Q

name of graph for 1/x

A

rectangular hyperbola

112
Q

what is the difference between the rectangular hyperbola and negative exponential?

A

The similarity between the two curves is that they both asymptote the x-axis. The difference is that the exponential curve meets the y-axis and the hyperbolic curve asymptotes the y-axis.

113
Q

define time constant Tau..

A

It is the time required for a process to complete if it continued at its initial rate of fall, i.e. it is the tangent to the graph at time = 0

The time taken for the magnitude of the variable to fall to 37% of its initial value

or
The time to fall to 1/e or 1/eth of its original value.

114
Q

how much of the process is complete in one time constant?

A

he process is 63% complete in one τ.

fallen to 37%

115
Q

how much of a process is complete after 2 and 3 time constants?

A

86% after 2
95% after 3

116
Q

can the Vd of a drug be greater than volume of the body?

A

yes - theoretical value

117
Q

how is loading dose calculated with Vd?

A

loading dose = steady state conc x Vd

divide this by Bio availability for oral drugs.

118
Q

oxygen can be toxic. how long before FiO2 of 1 will cause pulmonary changes?

A

12 hours

(for 0.8 FiO2 = 24hrs, 0.6 = 36 hrs)

it is toxic in dose dependant and time dependant effect

in hyperbaric conditions this is quicker e.g. at 2atm takes 6 hrs

119
Q

what are the pulmonary complications of hyperoxia?

A

infiltration of inflammatory cells
atelectasis
ARDS like picture

later - fibrosis

120
Q

how does high FiO2 promote atelectasis?

A

absorption atelectasis

secretions and blocked airway - promotes absorption of gas behind this without new ventilation

atelectasis reduces the FRC

121
Q

what effect does O2 toxicity have in neonates?

A

Retinopathy of prematurity
Necrotising enterocolitis
Bronchopulmonary dysplasia
Intracranial haemorrhage

122
Q

what are the neurological effects of hyperbaric O2?

A

At 2 atmospheres; paraesthesia, nausea, facial twitching, myopia, olfactory and gustatory disturbances
Above 2-3 atmospheres; convulsions may predominate

123
Q

can convulsions happen from normobaric O2 therapy?

A

no
only at hyperbaric

124
Q

when is FiO2 harmful i.e. what level?

A

anything more than 0.5

125
Q

what 2 main pathology can HYPERbaric O2 therapy lead to?

A

pulmonary oedema - smith effect
convulsions - bert effect

126
Q

what are the main factors that determine uptake of inhalation anaesthetic?

A

Alveolar fractional concentration
Blood:gas coefficient
Cardiac output
Alveolar:venous gradient

and conc/second gas effect

127
Q

how is alveolar fraction of inhalation agent increased?

A

increase Fi Agent
increase ventilation rate

128
Q

what other agent can cause concentration/ second gas effect?

A

Xenon

needs to be a non-potent agent used in high volumes

129
Q

how does ventilation affect the second gas effect?

A

increases it
increases the alveolar conc and hence diffusion

130
Q

how many isomers of GABA receptor are there?

A

over 30 -

responsible for the different effects of benzos e.g. a1 sedation, a2 anxiolysis, a3 muscle relaxation

131
Q

what are the receptors subunits of GABA?

A

2a , 2b , g

132
Q

what activates the NMDA receptor?

A

Glutamate and glycine are the natural co-ligands that bind to the receptor to open a central Ca2+ conducting pore.

ketamine, N20 and xenon all non-competitive antagonists

alcohol also effects NMDA - causes tolerance and withdrawal

133
Q

what type of receptor is NMDA?

A

ionotrophic

134
Q

what type of receptor is GABA B

A

metabotrophic

135
Q

where are glycine receptors found?

A

brain stem
spinal cord

136
Q

what is the equation for MAP?

A

MAP = SVR x CO

137
Q

what does increasing after load do to the frank starling curve?

A

reduced peak and to the right

138
Q

why can some ionotropic drugs e.g. B2 agonists cause drop in BP?

A

also affect peripheral B2
vasodilation

139
Q

what are the effects of adrenaline pharmacodynamically?

A

A low-dose infusion has inotropic β effects
increasing dose increases α action

Diastolic blood pressure can fall due to β2-linked peripheral vasodilatation

140
Q

what is the effect of dobutamine as a CVS drug?

A

Mainly stimulates β1-receptors with some β2- and α1-receptor action

Decreases left ventricular end diastolic pressure (LVEDP) via its action on peripheral β2-receptors (vasodilation)
B2 vasodilation also reduces preload

141
Q

what is the action of isophrenaline

A

Is a potent β1- and β2-receptor agonist – increasing cardiac output but afterload/systemic vascular resistance can drop due to peripheral β2 action

142
Q

what does aminophylline do to cardiac output?

A

increases

143
Q

name some phosphodiesterase inhibitors…

A

enoximone and milrinone - cardioselective used as ionotropes

aminophylline / theophylline - non selective (has some cardio effects)

144
Q

what is levosimendan?

A

Levosimendan increases myocyte sensitivity to Ca2+ by binding to troponin C.

used in severe acute HF

also causes peripheral vasodilation

145
Q

what does digoxin do to intracellular calcium?

A

increases it.

blocks Na/K ATPase
hence less sodium out of cell
therefore less Ca/Na exchanger activity - which normally takes Ca out.

145
Q

what receptors can be used by vasopressors

A

A1 adreno
vasopresin

146
Q

what is action of noradrenaline?

A

predominantly a1
some b1

hence increases BP
Has a minor inotropic action which is offset by a baroreceptor reflex vagal response to the increased blood pressure

147
Q

how can ephedrine be given?

A

orally or IV

148
Q

does ephedrine cross the placenta?

A

yes

149
Q

how do phenylephrine and metaraminol work?

A

a1 agonist
reflex brady

150
Q

what receptor does vasopressin work on to exert vasopressor effects? what type of receptor is this?

A

V1 - Gq

151
Q

which drug is dobutamine structurally similar too?

A

Dobutamine is structurally similar to isoprenaline

152
Q

which ventricle is more sensitive to microshock from current?

A

right ventricle

153
Q

what does the microshock induce in heart?

A

VF - no other arrythmias

154
Q

what wires does the electricity in an operating theatre have?

A

line neutral and earth wires

not live

only a single phase is supplied to operating room

155
Q

how can wires be protected from electrostatic interference?

A

The wires must be encased in a conductive NOT insulating layer

increasing distances - double the distance, will halve the interference

using lower frequency current - high frequencies, more interference

156
Q

can screened leads protect from electromagnetic interference?

A

no

157
Q

what is the difference between electrostatic and electromagnetic interference?

A

electromagnetic comes from magnet inducing current

electrostatic comes from imbalnces in charge

158
Q

how is electromagnetic inference affected by distance betwen leads?

A

Magnetic field strength varies as the reciprocal of the separation SQUARED

159
Q

what must the resistance of earth connection be?

A

less than 0.1 ohm

160
Q

what must leakage of earth current be less than?

A

0.5mA

161
Q

what earth is equiptment in hospitals connected too?

A

earth connection is the LOCAL earth and is NOT connected at or to the substation

162
Q

what is an earth surge test in electricity?

A

Earth surge test requires that the local earth can carry a current of 25A for 5 seconds

2.5V

163
Q

what is the star point in electricity?

A

the earth connection at the electrical substation

164
Q

what is the difference between cutting and coagulation mode in diathermy?

A

cutting
- continuous
- high freq (400KHz)
- lower voltage (400 - 1K volts)
- higher power (>100Wats)

coag
- interrupted
- low freq (250kHz) , high voltage (9KV)
- lower power (<100watts)

blended - both

165
Q

what frequency current does diathermy use?

A

v high frequency
up to 1 MHz

166
Q

how does remi potency compare to fentanyl

A

similar

167
Q

how much more potent is fentanyl than morphine?

A

100x

168
Q

what is more lipid soluble - pethidine or alfentanil?

A

alfentanil

169
Q

route for tramadol?

A

Oral
IV

170
Q

what is main effect of tramadol?

A

5HT3/NA reuptake block

then u receptor
then anatagonist at Ach

171
Q

morphine metabolism involves glucoronidation, what other pathways?

A

oxidation
demethylation
methylation

NOT Acetylation

172
Q

is clonidine good orally?

A

yes - 100% BO

173
Q

how is paracetamol converted to NAPQI?

A

oxidation

174
Q

what filters are used in ECG monitoring and diagnostic mode?

A

monitoring mode =
high pass filter = 0.5Hz (allows signals higher than this)
low pass filter = 40Hz

diagnostic = 0.05 to 100Hz

175
Q

what is main cause of pollution in paeds anaesthesia?

A

type of breathing circuit used

(the gas induction too but only for short time, a jackson rees modification of tee piece is open ended)

176
Q

which blood gas analysers use voltmeter vs ammeter?

A

CO2/ pH = volt
oxygen e.g. clark and fuel - amp

177
Q

How does mapelson F produce PEEP?

A

open ended bag , anaesthetist can close and open

NO APL valve

178
Q

pin index systems…

A

O2 2,5
air 1,5
N20 3, 5

CO2 1,6
entanox 7

179
Q

what does salbutamol do to lactate levels?

A

increase

i.e. after acute asthma treatment - hypoK and lactaemia

180
Q

describe the cormak and lehane view..

A

Grade I – full view of the glottis.
Grade IIa – partial view of the glottis
grade 2b - only arytenoids.
Grade III – epiglottis only visible.
Grade IV – neither epiglottis nor glottis visible.

181
Q

how does co-oximetry work?

A

takes blood sample
uses spectrophotometry to look at oxyHb, DeoxyHb, carboxyHb, methamoglobin

not in real time

not affected by skin colour (unlike pulse oximetry)

182
Q

what is meant by the sensitivity of a pacemaker and the stimulation threshold?

A

Sensitivity is the minimum required myocardial voltage to be detected as a p wave.

The minimum output required to consistently capture a heart beat is known as the stimulation threshold.

183
Q

what is the bainbridge reflex?

A

increase HR in response to atrial stretch

184
Q

what is anrep efect?

A

increased contractility in response to afterload

185
Q

what is the absolute humidty at 20, 37 degrees and 34 degrees

A

20 =17g/m3
37 = 44g/m3
34 = upper airways = 34g/m3

186
Q

why is theatres kept at 50-60% humidity?

A

reduces heat loss via vapourisation

reduces risk of sparks from build up of static charge

higher values uncomfortable for staff

187
Q

state methods of humification from least to most efficient?

A

Cold water bath
HME
Hot water bath
Bernoulli (gas driven) nebulizer
Ultrasonic nebulizer

188
Q

what humidity can soda lime achieve?

A

29mg/L
form of passive humification

189
Q

how many ports does HME filter have i.e. connections?

A

2 - 1x 15mm, 1x 22mm

+ sampling port for gas monitoring

190
Q

what type of material does HME filter contain?

A

hygroscopic - absorbs moisture

191
Q

how much does a HME increase resistance by?

A

0.1 to 2cmH20

royal college questions (4 decks)

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