Uscom Limited · ASX:UCM
Uscom — Technical Presentation (2008)
18 slides from Uscom's technical presentation, Jul 20, 2008
Slide 1: Validation of USCOM cardiac output measurements in preterm neonates by comparison with echocardiography
USCOM Validation of USCOM cardiac output measurements in preterm neonates by comparison with echocardiography R.A.Phillips, N.J Evans, M.Paradisis, D.M.Southwell, D.J.Burstow, M.J.West. The University of Queensland and the Prince Charles Hospital, Brisbane,Australia and The University of Sydney and
Slide 2: Introduction
USCOM Introduction • Haemodynamics important in neonates • Echo current method - expensive, complex, inaccessible – Doppler measures flow extremely accurately – Flow volume depends on accuracy of measuring Diam/XSA • Depends on 2D resolution • Operator competence • USCOM - simple, reduced cost, ± mo
Slide 3: Background
USCOM Background • Echo method • CO is modulated by rate and volume – How much and how often! – CO = vti x HR x XSA • Methods for determining XSA – XSA independent measurement - minute distance, stroke distance – Imaging - 2D, MRI – Anthropometry - Height, weight, BSA
Slide 4: Echo method: Ultrasound sensitivity
USCOM Echo method Ultrasound sensitivity Assume OTD=0.5cm and f=7.5MHz And c=fλ, c=1560m/s, Space res=SPL/2, SPL=4λ CIs based on the limits of spatial resolution are: OTD = 12.8% CO ≥ 28%
Slide 5: What about Anthropometry?
USCOM Echo method Is there a better way? What about Anthropometry?
Slide 6: Anthropometry
USCOM Anthropometry • Cardiac and great vessel dimensions are – 50% at birth – 65% at 12-18mths – 75% at 5yrs – 90% at 12yrs – Almost no change after maturity AV vs BSA AV vs Wt • Cardiac dimensions are related linearly to height, but show no independent correlation with gender, weight, or BSA • Lin
Slide 7: Anthropometry method
USCOM Anthropometry method .8 Results • RPAH subjects .7 • n=978 pre term neonates • 20 to 30wks gestational age .6 • Mean Weight = 0.986±0.269kg • Range = 0.42 to 1.69kg • PV = 0.507±0.059cm .5 • r = 0.649, p<0.000 .4 .3 4 00 6 00 8 00 1 000 1 200 1 400 1 60 0 1 8 00 WT
Slide 8: Neonatal nomograms
USCOM Neonatal nomograms Noenatal weight referenced nomograms Pulmonary and Aortic valve OTDs and XSA Aortic & Pulmonary OTD Aortic & Pulmonary XSA 0.8 0.5 0.7 0.4 0.6 0.5 0.3 0.4 0.2 0.3 0.2 0.1 0.1 0 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Patient Weight (kg) Patient Weight (
Slide 9: Objective
USCOM Objective • Compare OTD and CO in neonates • Methods – Echo: 2D and CW – USCOM: Anthropometry and CW
Slide 10: Method
USCOM Method • IRB approval • 37 unselected ICU subjects, 66 paired measures • 2D+CW vs USCOM with weight input • Blinded observations of PV and CO – Independent acquisition – Independent analysis – Data cross over for merging and analysis • Analysis – Comparison of means – Bland-Altman bias analysi
Slide 11: Results: Comparison of Echo and USCOM measures
USCOM Results • Comparison of Echo and USCOM measures (n=66) • Weight: Mean 1.13±0.47kg, Range: 0.39 to 3.09kg OTD(cm) %SD Range CO(l/min) %SD Range 0.52± 0.39- 0.36± 0.12- Echo 13.3 52.5 0.07 0.91 0.19 1.16 0.48± 0.41- 0.36± 0.13- USCOM 9.7 39.7 0.05 0.68 0.14 0.84
Slide 12: Results: Comparison of all PV diameter measures
USCOM Results • Comparison of all PV diameter measures 2D and USCOM PV diameter 1 0.9 0.8 Diameter (cm) 0.7 0.6 2D 0.5 USCOM 0.4 0.3 0.2 0.1 0 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64
Slide 13: Results: Comparison of all CO measures
USCOM Results • Comparison of all CO measures 2D+CW and USCOM CO measures 1.4 1.2 1 CO (L/Min) 0.8 2D+CW 0.6 USCOM 0.4 0.2 0 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53
Slide 14: Results: PV and CO scatterplots
USCOM Results • PV and CO scatterplots (n=66) PV annular diameter CO Echo vs USCOM 1 1.4 0.9 1.2 0.8 1 0.7 0.6 0.8 2D 0.5 USCOM 0.6 0.4 0.3 0.4 0.2 0.2 0.1 0 0 0 0.5 1 1.5 2 2.5 3 3.5 0 0.5 1 1.5 2 2.5 3 3.5 Weight (Kg) Weight (Kg) OTD(cm) Range CO(l/min) Range Echo 0.52±0.07 Echo 0.36±0.19 0.39-0.9
Slide 15: Results: Comparison of Echo and USCOM measures
USCOM Results • Comparison of Echo and USCOM measures (n=66) • Weight: Mean 1.13±0.47kg, Range: 0.39 to 3.09kg Mean SD % Diff r p Diff ratio 0.52± OTD 8.3 0.7491 <0.005 1:0.73 0.07 0.00± CO -3.7 0.9134 <0.005 1:0.76 0.08
Slide 16: Results: Mean difference between Echo and USCOM
USCOM Results • Mean difference between Echo and USCOM (n=66) PV d iam e t er 2 D vs USCOM CO Ech o vs USCOM .3 .4 .3 .2 .2 .1 .1 - .0 0 .0 - .1 - .1 - .2 Mean diff = 0.04±0.05cm Mean diff = 0.00±0.08L/min - .2 Mean of means = 0.50±0.05cm - .3 Mean of means = 0.36±0.16L/min Mean % error = 8.3±8.2 Me
Slide 17: Conclusion
USCOM Conclusion • USCOM valid down to 0.12l/min and 390gms • CO SDs by USCOM 25% less than echo and thus may be more sensitive for detection of haemodynamic changes • USCOM validated and safe method for haemodynamic management in neonates
Slide 18: Thank You!
USCOM Thank You!