Emergency Department Ultrasound
at Auckland Hospital
FAST and AAA: The first year
Objectives
• The role of FAST
• History of ED ultrasound at Auckland
Hospital
• The ultrasound credentialling process
• How we performed in the first year
• How we compare to the rest of the world
• Where we go from here
FAST
•
•
•
•
Focused
Assessment
Sonography
Trauma
FAST
• Integral part of initial trauma workup
• Proven
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Quick
Safe
Reliable
Reproducible
Repeatable
FAST
• Pitfalls
– Poor sonographer
– Poor scan
• Air
• Obesity
– Negative FAST doesn’t exclude injury!
– Failure to serially examine the patient
History
• 1998 Purchased portable ultrasound
machine
• 1998 First Australasian FAST course
• 1999-2001 Sporadic use of ultrasound
• Dec 2000 Formal Emergency Ultrasound
credentialling program
• Feb 2001 1st credentialled ED sonographers
The Credentialling Process Background
Radiologist
Clinician
Radiologist
Clinician
The Credentialling Process Background
• Much debate in literature last 10 years
• Consensus meeting
• Each department decide own credentialling process
• 200 scans and ongoing audit
• Subsequent literature
– Shackford 1999 4 yr experience
• 50 scans
• Suggests acceptable error rates
The Credentialling Process Background
• Workshop beneficial
– Rozycki 1996
• Exit exam
– Sisley 1999
The Credentialling Process Background
• American College of Emergency Physicians
2001
– 8 workshop hours
– 25 scans in each of 6 areas
– Can be partially credentialled
• Only 1/76 departments met criteria
– Boulanger 2000
The Credentialling Process Background
• Australasian College for Emergency
Medicine
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16 workshop hours
25 Accurate scans for FAST
15 Accurate scans for AAA
>50% clinically indicated
Proctored by credentialled/ultrasound qualified
person
– Exit exam
Auckland ED
• Adopted ACEM guideline December 2000
• 4 sonographers
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Satisfied workshop requirement
Scans should not alter management
All measured against ‘gold standard’
Proctored by radiologist
– Standardised form
– Monthly/bimonthly
– Modified criteria for scans
– 100% clinically indicated
– Exit examination February 2001
Results FAST
• 1 ED registrar ‘credentialled’ by June 2001
– 79% Indicated scans
• 2/3 ED Specialists credentialled by Feb
2002
– All scans clinically indicated
Results FAST
• For Detection Any Free Fluid
• 113 scans in 102 patients over 13 months
– 9 scanned by 2 sonographers
– 1 scanned by 3 sonographers
Results FAST
(Any Free Fluid) n=113
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•
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•
TP
TN
FP
FN
20
83
3
7
•
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•
•
•
Sn
Sp
PPV
NPV
74.1%
96.5%
87%
92%
Accuracy 91.2%
Results FAST
(Laparotomy or Extra Investigation)
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•
•
•
TP
TN
FP
FN
11
89
5
2
•
•
•
•
•
Sn
Sp
PPV
NPV
n=107
84.6%
94.7%
68.8%
97.8%
Accuracy 93.5%
Results FAST
Existing literature
• vs gold standard, novice sonographers
• 3 studies
• Sn 69-79%
• Sp 96-98%
• vs clinical observation and experienced
sonographers
• Sn
• Sp
80-98%
>90%
Errors FAST
• 7 FN
– 5/7 Trivial fluid, conservative management
– 1 penetrating trauma with minor injury
– 1 blunt trauma bladder injury, stable
• All views adequate and correct
interpretation according to radiologist
Errors FAST
• 3 FP
– 1 “ascites”
– 1 “?pericardial effusion”
– 1 Retroperitoneal and abdominal wall
haematomas
• Adequate views but incorrect interpretation
Result of errors FAST
• 1 CT scan thorax for “?Pericardial effusion”
Emergency Department
Ultrasound for AAA
• 2 Case series in literature
Results AAA
• 66 Scans in 58 Patients in 12 months
– 5 Scanned by 2 sonographers
– 1 Scanned by all 4
• 3/4 sufficient scans to meet requirement
Results AAA
n=66
•
•
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TP
TN
FN
FP
26
39
1
0
•
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•
•
•
Sn
SP
PPV
NPV
96.3%
100%
96.3%
97.5%
Accuracy 98.3%
“Error” AAA
• Free air obscured 6cm AAA
• Free fluid detected in Morison’s and
Splenorenal recesses
• Found to have perforated DU
AAA Existing Literature
• Shuman 1998
– n=60
• Sn 97%
• Sp 100%
• Kuhn 2000
– n=68
• Sn 100%
• Sp 95%
Time Taken to Scan
• FAST median 5min (1-20)
• AAA median 3.5 (1-16)
• Similar to literature published
FAST
Learning Curve
• Debate about this
• Shackford only author to look at initial
experience
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Suggests 10 scans before proficient
Showed ‘Institutional learning curve’
12 Individuals = wide variation in error rates
Only 4/12 had >25 scans in 4 years
FAST
Learning Curve
Pooled Error Rates for EU
0.12
Error Rate
0.10
0.08
Any Free Fluid
0.06
Clinically Significant
0.04
0.02
0.00
5
10
15
20
25
Number of Scans
30
33
FAST
Learning Curve
• Error rate <10%
• Most ‘errors’ clinically insignificant
• Individual variation
Potential Bias
• Patients not consecutive
– Opportunity for pre-selection of patients
• Individual sonographers could discard
unsatisfactory scans prior to proctoring
Summary
• Emergency Department Ultrasound is
established in Auckland Hospital
• Accuracy mirrors existing literature
• Pitfalls exist and should be considered
The future
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Credentialling continues
Credentialled sonographers record in notes
Clinical management may alter
Ongoing audit
Expanded indications
– Unstable patient with abdominal pain
• Is there free fluid?
Case 1
• 37f
– 4hr Abdominal pain
– Collapse and seizure
– Shock
– Arrives ED 1755
– SLOH 1806
Case 1
• OT 1815
Case 2
• 28f
– 1/2 hr Abdominal pain
– HR 84, SBP 90, RR 16
– Arrives ED 0910
– S/B registrar 1000
– SLOH 1018
Case 2
• Urine pregnancy test 1025, positive
Case 2
• OT 1055
Case 3
• 19m
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Fall from tree
Collapse at home
Fighting en route
Arrives ED 1635
FAST 1645
Case 3
• OT for thoracotomy