1.
Clinical Skills Session
Update day March 2016

2.
Non-vis rates……….
Myths
Sonosite machines have higher non-vis rates than GE machines
• The non-vis rates are very similar
• The sonosite has less functionality
• One of the reasons for it being chosen
• Newer machines do have better imaging at depth but not sufficient to
warrant new machines as yet
Areas with high non-vis rates have higher levels of obese patients
• All screening programmes have mixed degrees of socio-economic and
ethnic backgrounds
• Very similar across the country
• No obesity epidemic within Oxfordshire
Part time staff have higher non-vis rates than full time staff
• Very similar rates across the programmes
• May take longer time to stabilise once training has been completed

3.
• High non vis rates are usually down to technician
confidence at measuring the aorta at depth
• National average is 1.43%
• Achievable standard is 3.0%
• NAAASP are looking at reducing the threshold for non-
visualisation

4.
Current Programme PatientType Numerator Denominator Percentage England average
SOM_Somerset & North Devon AAA Screening Cohort Cohort 5 4236 0.12% 1.43%
HAM_Hampshire AAA Screening Cohort Cohort 15 7523 0.20% 1.43%
KEN_Kent & Medway AAA Screening Cohort Cohort 23 8299 0.28% 1.43%
LNC_Lincolnshire AAA Screening Cohort Cohort 13 4142 0.31% 1.43%
NOE_North East AAA Screening Cohort Cohort 49 15258 0.32% 1.43%
NCL_North Central London AAA Screening Cohort Cohort 18 5217 0.35% 1.43%
YOH_North Yorks and Humber AAA Screening Cohort Cohort 29 7919 0.37% 1.43%
NOR_Norfolk & Waveney AAA Screening Cohort Cohort 24 5497 0.44% 1.43%
FRV_Five Rivers AAA Screening Cohort Cohort 21 4040 0.52% 1.43%
ESX_Essex AAA Screening Cohort Cohort 41 6517 0.63% 1.43%
BLM_Beds Luton & MK AAA Screening Cohort Cohort 25 3729 0.67% 1.43%
NEL_North East London AAA Screening Cohort Cohort 35 5087 0.69% 1.43%
LEI_Leicester AAA Screening Cohort Cohort 32 4615 0.69% 1.43%
WSU_Sussex AAA Screening Cohort Cohort 60 7858 0.76% 1.43%
SYB_South Yorkshire Blaw AAA Screening Cohort Cohort 55 6838 0.80% 1.43%
CML_Cumbria & Lancashire AAA Screening Cohort Cohort 76 9313 0.82% 1.43%
SDE_South Devon AAA Screening Cohort Cohort 35 4225 0.83% 1.43%
BCO_Black Country AAA Screening Cohort Cohort 43 5177 0.83% 1.43%
NWL_North West London AAA Screening Cohort Cohort 57 6787 0.84% 1.43%
HFD_Hertfordshire AAA Screening Cohort Cohort 40 4743 0.84% 1.43%
SWL_South West London AAA Screening Cohort Cohort 55 6119 0.90% 1.43%
BBW_Bristol Bath & Weston AAA Screening Cohort Cohort 45 4838 0.93% 1.43%
GLO_Gloucester & Swindon AAA Screening Cohort Cohort 43 4378 0.98% 1.43%
HRW_Hereford and Worcester AAA Screening Cohort Cohort 43 4195 1.03% 1.43%
NRH_Northamptonshire AAA Screening Cohort Cohort 39 3454 1.13% 1.43%
HOE_Central England AAA Screening Cohort Cohort 104 7915 1.31% 1.43%
CYH_Central Yorkshire AAA Screening Cohort Cohort 76 5663 1.34% 1.43%
WSR_West Surrey AAA Screening Cohort Cohort 77 5375 1.43% 1.43%
CAM_Cambridgeshire AAA Screening Cohort Cohort 75 4974 1.51% 1.43%
DBY_Derbyshire AAA Screening Cohort Cohort 108 6880 1.57% 1.43%
NSS_N & S Staffordshire AAA Screening Cohort Cohort 112 5566 2.01% 1.43%
WYO_West Yorkshire AAA Screening Cohort Cohort 96 4627 2.07% 1.43%
COV_Coventry & Warwick AAA Screening Cohort Cohort 106 4234 2.50% 1.43%
SEL_South East London AAA Screening Cohort Cohort 131 5062 2.59% 1.43%
DOW_Dorset and Wiltshire AAA Screening Cohort Cohort 182 6632 2.74% 1.43%
MAN_Manchester AAA Screening Cohort Cohort 388 12900 3.01% 1.43%
CHM_Cheshire & Merseyside AAA Screening Cohort Cohort 282 9234 3.05% 1.43%
THV_Thames Valley AAA Screening Cohort Cohort 323 8643 3.74% 1.43%
PEN_Peninsula AAA Screening Cohort Cohort 198 5100 3.88% 1.43%
STW_Shrops Telf’d & Wrekin AAA Screening Cohort Cohort 170 3767 4.51% 1.43%
NOT_Nottinghamshire AAA Screening Cohort Cohort 237 4621 5.13%
1.43%

5.
How to improve the images…..
• What’s the point?
• Hopefully reduce the non-vis rates
• Provides a better service to the subjects being screened
• Improves performance and cost effectiveness of the programme
• Ensures that the screening programmes and technicians are
providing a quality service to the community based on quality
standards that can be measured
• May seem like a blunt tool
• Every image should be optimised before taking a measurement
• The images on obese patients will never be as good as those on
slimmer patients
• Use the non-vis guidance
5Thames Valley Update 12/11/14

6.
• Increase depth
• Sounds counter intuitive
• Sonosite machines have the focal zone in the middle of the screen
• Decrease the dynamic range
• Reduces the number of shades of grey and therefore should help
highlight the vessel walls
• Can be reduced to -3 in obese patients on sonosite
• Alter as much as required on the other machines
• Reduce the frequency of the
probe/ultrasound
• Reducing the frequency of the probe will increase the wavelength
• Improves penetration
• Reduces image quality
6Thames Valley Update 12/11/14

7.
• Remove harmonic imaging
• Improves the frame rate
• US machine has to wait less time before acquiring the
image
• Can make image worse
• Remove compound imaging
• Improves frame rate
• Can make image worse
• Always adjust the gain when taking this on or off
7Thames Valley Update 12/11/14

8.
• Press harder
• Brings aorta nearer to the probe
• Mindful of patient comfort level
• Image in transverse
• Easier to image in transverse
• Think of transverse as your friend
• If you get stuck rotate probe
• Don’t get obsessed with anterior vessels or
IVC
• Might not see them in obese patients
• 50% visualisation rate
8Thames Valley Update 12/11/14

9.
• Use two hands to press the probe down
• Mindful of MSK injury
• Get colleague to freeze
• Get patient to breath in and hold breath
• Relaxes the diaphragm
• Push probe down when breathing in
• Stop the scan
• Get colleague to have a look
• 2 mins away can give you different perspective
• Know your limitations
9Thames Valley Update 12/11/14

10.
Hints and tips
Increase depth
Decrease dynamic range
Reduce frequency of the probe
Remove harmonic imaging
Remove compound imaging
Press harder
Transverse imaging
Anterior vessels
Use two hands
Get patient to breath in, hold it and then breath out
Ask colleague to look/take a break/know when to stop
Tell patient to wait outside

11.
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