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Pre operative, non-invasive cardiac output measurement

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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. 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
  2. 2. Conflict of Interest Honoraria Financial help with travel to attend scientific meetings From  Deltex Medical  Intavent  Astratech
  3. 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. 4. The USCOM Device Continuous wave US Aortic and pulmonary valves Trans-cutaneous Completely non-invasive Neonates to Geriatrics
  5. 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. 6. USCOM looks at flow through valves Different waveform from desc. aorta Velocity-time integral VTi
  7. 7. Aortic valve outflow Fibrous Annulus Rigid  Little systolic change Constant size in adulthood Linear relationship with height
  8. 8. Outflow Tract Diameter: Linearly related to height in adults Linearly related to height in children Neonates <50cm weight is used
  9. 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
  10. 10. Pulmonary Valve
  11. 11. Learning Curve? 4 novice operators 1 experienced operator SV measurements Before Passive leg raise (PLR) After PLR In 25 healthy volunteers One ‘novice’ vs expert compared in 24 patients
  12. 12. First 10 measurements Median(IQR) PrePLR PostPLR Experienced 71(59 – 85) 87(76 – 93) Novice 66(53 – 76) 77(67 – 86) Measurements 20 – 25 Experienced 64(57 – 75) 79(74 – 87) Novice 65(56 – 71) 78(73 – 86)
  13. 13. 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)
  14. 14. Comparison with ODM 135 paired observations in theatre
  15. 15. Bland–Altman plot All 135 paired readings Mean Bias 5.9ml, 95%CI -20-+32, % error 30%
  16. 16. 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%.
  17. 17. Testing for Concordance
  18. 18. Bedside Inotropy Acknowledgement Prof. B.Smith and Veronica Madigan, Bathurst Base Hospital and Charles Sturt University. USCOM allows for Inotropy assessment
  19. 19. Inotropy – heart power External cardiac work Kinetic energy – flow of the blood Potential energy – generation of BP Power is work per unit time
  20. 20. 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
  21. 21. 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
  22. 22. 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
  23. 23. 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
  24. 24. 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
  25. 25. 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
  26. 26. SMII Pre CPET vs AT
  27. 27. SMII Post CPET vs AT Correlation Coefficient 0.56
  28. 28. 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
  29. 29. 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
  30. 30. 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
  31. 31. 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
  32. 32. PH Symptoms and Signs of LVF Low CI Very high SVR and PKR Low Inotropy Plan Stop Atenolol and ISMN Additional diuretic (Co-Amilofruse)
  33. 33. PH 4 weeks later
  34. 34. 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
  35. 35. 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
  36. 36. PH 3 days level 1 bed Home day 11 Echo 8 weeks later Dilated and severely impaired LV EF 35% 6/12 Remains well
  37. 37. 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

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