A method for mathematical arterialization of venous blood gas v- TAC - - PowerPoint PPT Presentation

v-TAC™ is an advanced software algorithm that converts venous blood gas, combined with an SpO2 measurement, to arterial blood gas values with great accuracy and precision. v-TAC™ is about:

• Clinical and operational work-flow optimisation
• Improving patient satisfaction

A method for mathematical arterialization of venous blood gas

Bjarne Flou

CEO, OBI Medical

v-TAC drives optimisation of workflow in blood gas testing

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Arterial Blood Gas (ABG)

• Gold standard

But

• Hard to get…
• Painful

Electrolytes values Metabolic values Acid-Base & Blood gas values

Venous Blood Gas (VBG)

• Easy to get
• Electrolytes, metabolics OK

But

• Not ideal screening tool
• ABG follow-up

needed

• Poor indicator of
• Progression of illness
• Response to

treatment

Metabolic values

Trend towards using VBG where possible

Acid-Base & Blood gas values Electrolytes values

With arterialisation by v-TAC, a VBG becomes a true substitute to ABG and CBG in multiple clinical applications

Arterial

Capillary Blood Gas (CBG)

• Accepted substitute for many

clinical applications But

• Complex technique
• Operator dependent

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What is v-TAC™?

v-TAC™ software algorithm

SpO2

pH pCO2 pO2 Hb sO2 (FMetHB) (FCOHb) From Pulse

• ximeter

pH pCO2 pO2* HCO3

• BE

paO2/FiO2 Ratio* (sO2) 2,3 DPG tO2 tCO2

SBE, SBC, co-oximetry etc. available from the VBG *pO2 >10 kPa reported as ”> 10 kPa”

(Software application)

Peripheral venous blood gas values

(Adults age 18+)

Calculated arterial blood gas

Watch Prof. Dr. Stephen E. Rees present the principles of the v-TAC methodon our Youtube channel:

https://www.youtube.com/channel/UCQT2L5zpM_VV71uQH1VT3Bw/videos

Based on Siggaard-Andersen Blood Model

When can v-TAC be used?

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Can a stable

• xygen sat (SpO2)

at 75%* or above be measured?

YES Patients age 18+ All clinical indications NO

Can a peripheral venous sample be drawn?

Convert using the v-TAC software Use alternative method, such as ABG

*Configurable, default = 80%

YES NO

Indications of too poor circulation:

• Difficulty measuring SpO2 (on the

arm used for the sample)

• The arm/peripheral is cold/blue
• Long stasis time for blood-sampling
• The patient develops

catecholamines (or similar) Other indications:

• Peripheral is warm, red and dry; a

pulse can be felt

• Capillary response is normal

Typical Radiometer/v-TAC setup (Example from DK)

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ABL configuration:

• A sample type ‘v-TAC’ is configured on the ABL to identify and mark

samples for arterialisation by v-TAC™

• When ‘v-TAC’ is selected, the SpO2 value shall be entered into a

mandatory input field ABL operation

• In daily operation, when the venous blood sample has been taken

and SpO2 measured, the ‘v-TAC’ button is selected and SpO2 entered

• The v-TAC results are immediately sent to the printer (optinal) and/or

sent to the LIS/EPR (optional) For additional information please request technical manual

v-TAC printer next to ABL configured for v-TAC

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Print from v-TAC Print from BGA

Selected venous results from BGA print is transferred to v-TAC print

v-TAC™ printed report (A4)

Printer: For example A4 network laser printer (recommended)

v-TAC calculated arterial values

v-TAC results in LIS

Example from North Denmark Regional Hospital (LABKA-II)

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v-TAC results clearly marked ‘v-TAC’ according to nomenklatur defined by MEDCOM and following IUPAC standards

Venous Results Calculated v-TAC arterial results

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pH

v-TAC™ & ABG repeatability vs ABG

±95% Limits of agreement (v-TAC) Bias ABG-2 vs ABG-1 (n=73, Toftegaard, 2008) v-TAC vs ABG-1 (n=416, Pooled data)

v-TAC™ Bias ±95% Limits of Agreement

• 0.001 ±0.03

ABG-2 vs ABG-1 (n=73, Toftegaard, 2008) v-TAC vs ABG-1 (n=416, Pooled data)

Plots compare v-TAC pH vs ABG-1 (black dots) withToftegaard studying ABG-2 vs ABG-1 repeatability (red dots).

Conclusion: v-TAC pH repeatability is comparable to arterial repeatability

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pCO2

v-TAC™ & ABG repeatability vs ABG

ABG-2 vs ABG-1 (n=73, Toftegaard, 2008) v-TAC vs ABG-1 (n=416, Pooled data)

v-TAC™ Bias ±95% Limits of Agreement

• 0.043 ±0.53 kPa

±95% Limits of agreement (v-TAC) Bias ABG-2 vs ABG-1 (n=73, Toftegaard, 2008) v-TAC vs ABG-1 (n=416, Pooled data)

Plots compare v-TAC pCO2 vs ABG-1 (black dots) withToftegaard studying ABG-2 vs ABG-1 repeatability (red dots).

Conclusion: v-TAC pCO2 repeatability is comparable to arterial repeatability

pO2

v-TAC™ & ABG repeatability vs ABG

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ABG-2 vs ABG-1 (n=73, Toftegaard, 2008) v-TAC vs ABG-1 (n=208, Pooled data) ABG-2 vs ABG-1 (n=192, Mallat et al., 2015)

Plots compare v-TAC pO2 vs ABG-1 (black dots) with two sources of arterial vs arterial repeatability: Mallat (green dots, studying ABG repeatability while minimizing pre-analytical and biological contributions) and Toftegaard (red dots). Conclusion: v-TAC pO2 repeatability is comparable to arterial repeatability for values of pO2 up to 10 kPa

Zoom area

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Toftegaard ±95% Limits of agreement Mallat ±95% Limits of agreement

Plot explanation: Notes:

• v-TAC reports calculated pO2 values between 0 to 10 kPa. If calculated pO2 exceeds 10 kPa, v-TAC reports ”pO2 > 10 kPa”
• Tygesen et al. Group-B excluded due to 10-15 minutes between v-TAC and ABG

Venipuncture is easier and less paintful for the patient compared to arterial punctures

Recent UK study show that:

• On a scale from 0 – 10, pain associated

with arterial punctures score avg 4, while venipunctures score 1

• To make 234 blood samples it takes

approximately 330 arterial attempts, while the same can be done with approximately 260 venous attempts

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Source: McKeever et al. 2016, Using venous blood gas analysis in the assessment of COPD exacerbation: a prospekctive cohort study (REF635)

~330 ~260

Thank you!

More information: www.obimedical.com

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