Effective, non-invasive cardiac output with good comparison and concordance with ODM.
In Pre-op setting allows advanced cardiac assessment, Inotropy appears to correlate with AT and enables effective use of CVS medication.
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Pre operative, non-invasive cardiac output measurement
1. Pre-operative, non-invasive
cardiac output measurement
H.G. WAKELING
Department of Anaesthesia
Western Sussex Hospitals NHS Trust
Chair
Cancer Enhanced Survival Clinical Advisory Group
SE Coast Strategic Network and Clinical Senate
NHS England
howard.wakeling@nhs.net
3. The USCOM Device
Describe the USCOM Device
What it does
How to use it
Learning curve identification
Correlation with Oesophageal Doppler
Case Histories
Bedside Inotropy and CPET
4. The USCOM Device
Continuous wave US
Aortic and pulmonary
valves
Trans-cutaneous
Completely non-invasive
Neonates to Geriatrics
5. How does it work?
Fd= 2Ft x V x cosθ
C
Fd Doppler frequency
Ft Transmitted frequency
V Velocity of blood
θ Angle between beam
and blood flow
C Velocity of sound in soft
tissue (constant)
6. USCOM looks at
flow through valves
Different waveform
from desc. aorta
Velocity-time integral
VTi
7. Aortic valve outflow
Fibrous Annulus
Rigid
Little systolic change
Constant size in
adulthood
Linear relationship
with height
8. Outflow Tract Diameter:
Linearly related to
height in adults
Linearly related to
height in children
Neonates <50cm
weight is used
9. 1 Start of systole
2 Valve opening
3 Peak velocity
4 End of blood flow
valve closes
5 VTi
6 Diastolic flow
Early diastolic filling
Atrial contraction
17. Inter-rater correlation between assessors
A: during training, pre leg raise (R2
= 0.71) B: during training, post leg raise (R2
= 0.59)
C: post-training, pre leg raise (R2
= 0.94) D: post training, post leg raise (R2
= 0.95)
20. Testing for Concordance
77 paired readings pre/post fluid
45% of challenges SVODM ↑≥10%
94% SVUSCOM also ↑
5 cases SVUSCOM ≥10% when no ΔSVODM
Sensitivity was 94%, Specificity 88%
Positive predictive value (PPV) 87%
Negative predictive value (NPV) of 95%.
22. Bedside Inotropy
Acknowledgement Prof. B.Smith and Veronica Madigan, Bathurst Base Hospital and
Charles Sturt University.
USCOM allows for Inotropy assessment
23. Inotropy – heart power
External cardiac work
Kinetic energy – flow of the blood
Potential energy – generation of BP
Power is work per unit time
24. Kinetic energy
½.mass.velocity2
Mass = SV x Density
Density is dependant on Hb
Mean velocity
Velocity sampled every 10 milliseconds
If flow time 360ms – 36 readings to
average
25. Potential Energy
Δ Pressure x Δ Volume
Δ Pressure
Pressure leaving the heart (MAP) minus
pressure of blood entering heart (CVP)
Δ Volume
Stroke Volume
26. Work = KE + PE
Power is work per unit time
Time for heart to work is the flow time
Measured in Watts
Power = Kinetic energy + Potential energy
Flow time Flow time
Indexed by dividing by BSA
Smith-Madigan Inotropy Index (SMII) W.m-2
27. Application of Inotropy Index
Normal heart SMII 1.6 – 2.2 W.m-2
LVF patients SMII 0.4 – 1.0 W.m-2
Failing heart 33% normal inotropy
28. Ratio of Potential to Kinetic energy
PKR
Normally 30:1
Sepsis much lower – possibly only 3:1
Flow but little Pressure
Arterial hypertension - vasoconstriction
May be over 150:1
Very little flow
Very high SVR
29. Comparison with CPET data
USCOM measurements pre and
immediately post CPET
23 patients so far
Preliminary data shows good
correlation between SMII and
Anaerobic Threshold
Both pre and post CPET
32. SMII vs AT
In addition 3 patients with low SMII
failed to reach AT!
So preliminary data suggests SMII may
be useful as correlates well with AT
Important - independent of exercise
33. Case history
Specialist Pre-assessment Anaesthesia and Medicine Clinic (SPAM)
Mr PH
88 years 80.6Kg 173.5cm
Extended right hemicolectomy
Poor exercise tolerance
Orthopnoea, swollen ankles, PND+
No Angina
34. Medications and PMH
Atenolol 50mg od
Frusemide 40mg od
ISMN 60mg pd
Iron
GTN
Ca Bladder
TURP
Ischaemic heart
disease
Pleural effusions
2012
‘normal’ echo
35.
36. PH
CI 1.1 l/min/m2
FT 303ms
SVRI 6384 ds.cm-5
m2
DO2 300 ml/min
INO 0.68 W/m2
PKR 132
37. PH
Symptoms and Signs of LVF
Low CI
Very high SVR and PKR
Low Inotropy
Plan
Stop Atenolol and ISMN
Additional diuretic (Co-Amilofruse)
39. PH
Before and After
CI 1.1
FT 303
SVRI 6384
DO2 300
INO 0.68
PKR 132
2.1 l/min/m2
268 ms
3679 ds.cm-5
m2
572 ml/min
0.93 W/m2
107
40. PH
Successful surgery
Stroke Volume optimisation ODM
No crystalloid
Low dose dobutamine 24 hours
2 days level HDU
Troponin rise
Echo confirmed diastolic heart failure
Aspirin, ramipril clopidogrel started
2 days level 1
41. PH
3 days level 1 bed
Home day 11
Echo 8 weeks later
Dilated and severely impaired LV
EF 35%
6/12
Remains well
42. USCOM Summary
Effective, non-invasive cardiac output
4 hour or 50 uses learning curve
Good comparison with ODM
Good concordance with ODM
In Pre-op setting:
Allows advanced cardiac assessment
Inotropy appears to correlate with AT
Enables effective use of CVS medication