Is Venous to Arterial Conversion (v-TAC) of Blood Gas Reliable in Critical Ill Patients in the ICU?

Sepsis Clinical Trial

Official title:

Utility of Mathematically Converted Venous to Arterial Blood Gas for Clinical Monitoring

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT03309423
• Other study ID #: v-TAC-ICU
• Status: Recruiting
• Phase: N/A
• First received: October 4, 2017
• Last updated: October 12, 2017
• Start date: October 9, 2017
• Est. completion date: March 30, 2018

Study information

• Verified date: October 2017
• Source: Aalborg University
• Contact: Mads Lumholdt
• Phone: +45 51914156
• Email: m.lumholdt[@]rn.dk
• Is FDA regulated: No
• Study type: Observational

Clinical Trial Summary

Objective: Arterial blood gas (ABG) is essential in the clinical assessment of potential acutely ill patients venous to arterial conversion (v-TAC), a mathematical method, has recently been developed to convert peripheral venous blood gas (VBG) values to arterialized VBG (aVBG) values. The aim of this study is to test the reliability of aVBG compared to ABG in an intensive care unit (ICU) setting.

Method: Consecutive patients admitted to the ICU with pH values <7,35 or >7,45 are included in this study. Paired ABG and aVBG samples are drawn from patients via arterial catheter, central venous catheter and/or peripheral venous catheter and compared.

Description:

Arterial blood gas (ABG) analysis is essential in assessment of respiratory and metabolic status in acutely ill patients. In comparison to peripheral venous blood (PVG) sampling, the ABG sampling procedure is more painful for the patient and technically more challenging for the clinician to perform. Other drawbacks of ABG sampling include adverse events such as subcutaneous hematoma, arterial thrombosis or embolization, and pseudoaneurysms.

Peripheral venous blood gas (VBG) sampling has been suggested as an alternative to the ABG procedure. This procedure causes less patient discomfort and the sample can be analysed in combination with other venous blood tests. Studies have revealed that pH and bicarbonate have good correlation, whereas venous and arterial blood gasses (pO2 and pCO2) show low agreement.

However, a new method has been developed to calculate ABG values mathematically from peripheral venous blood by use of venous to arterial conversion (v-TAC) software (Obimedical, Denmark), supplemented with oxygen saturation measured by pulse oximetry. The principle of the method is a mathematical transformation of VBG values to arterialized values (aVBG) by simulating the transport of blood back through the tissue. Initial testing of the method in an emergency department setting showed acceptable clinical congruence between arterial and mathematically arterialized pH and pCO2 with a small difference (+/- SD) on 0.001 +/- 0.024 and 0.00 0.46 kPa, respectively. However, inaccurate values of pO2 were seen when oxygen saturation measured by pulse oximetry was above 96%, due to the flat shape of the oxygen dissociation curve (ODC).

Although most patients in the ICU have arterial catheters therefrom ABG can be drawn, applying arterial catheter is difficult or even impossible in some patients. In relation to step-down some patients get arterial catheters removed and in the event of deterioration in patients acid-base or respiratory disease aVBG could prove useful as a minimally invasive tool to assess patients status.

The aim of this study is to investigate if v-TAC is reliable and safe to use in patients with critically respiratory or metabolic disease admitted to the ICU.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 50
• Est. completion date: March 30, 2018
• Est. primary completion date: January 30, 2018
• Accepts healthy volunteers: No
• Gender: All
• Age group: N/A and older

Eligibility

Inclusion Criteria:

• All patients admitted to the intensive care with the following:

• Arterial catheter for other purpose.

• Peripheral venous catheter or central venous catheter for other purpose.

Exclusion Criteria:

• Normal pH in arterial blood gas.

Related Conditions & MeSH terms

• Abdomen, Acute
• Acidosis
• Alkalosis
• Metabolic Disease
• Metabolic Diseases
• Pulmonary Valve Insufficiency
• Respiratory Insufficiency
• Sepsis

Intervention

Diagnostic Test:
• venous to arterial conversion (v-TAC)
Venous to arterial conversion (v-TAC) is a software (Obimedical, Denmark), which can convert venous blood gas values to arterial blood gas values. The principle of the method is a mathematical transformation of VBG values to arterialized values (aVBG) by simulating the transport of blood back through the tissue. To facilitate this simulation the following physiologically relevant assumptions were made: 1) The peripheral extremity was well perfused; 2) change in base excess across the tissue sampling site was approximately zero; 3) the respiratory quotient (rate of CO2 production and O2 utilisation over capillaries) could not vary outside the range 0.7 and 1.0, and 4) the haemoglobin concentration was constant from artery to vein.

Locations

Country	Name	City	State
Denmark	Faculty of Medicine, Doctoral School, Ph.d. study	Aalborg	North Denmark

Sponsors (2)

Lead Sponsor	Collaborator
Aalborg University	North Denmark Regional Hospital

Country where clinical trial is conducted

Denmark, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Lin's Concordance correlation coefficient (CCC)	Comparison of pH between ABG and aVBG (from peripheral venous catheter). The closer CCC is to 1 the better correlation.	1. january 2018
Primary	Lin's Concordance correlation coefficient (CCC)	Comparison of pCO2 (Unit of Measurement: kilopascal) between ABG and aVBG (from peripheral venous catheter). The closer CCC is to 1 the better correlation.	1. january 2018
Primary	Lin's Concordance correlation coefficient (CCC)	Comparison of pO2 (Unit of Measurement: kilopascal) between ABG and aVBG (from peripheral venous catheter). The closer CCC is to 1 the better correlation.	1. january 2018
Primary	Lin's Concordance correlation coefficient (CCC)	Comparison of pH between ABG and aVBG (from central venous catheter). The closer CCC is to 1 the better correlation.	1. january 2018
Primary	Lin's Concordance correlation coefficient (CCC)	Comparison of pCO2 (Unit of Measurement: kilopascal) between ABG and aVBG (from central venous catheter). The closer CCC is to 1 the better correlation.	1. january 2018
Primary	Lin's Concordance correlation coefficient (CCC)	Comparison of pO2 (Unit of Measurement: kilopascal) between ABG and aVBG (from central venous catheter). The closer CCC is to 1 the better correlation.	1. january 2018
Primary	Bland and Altman's plot	Mean difference and 95% limits-of-agreement of pH between ABG and aVBG (from peripheral venous catheter)	1. january 2018
Primary	Bland and Altman's plot	Mean difference and 95% limits-of-agreement of pCO2 (Unit of Measurement: kilopascal) between ABG and aVBG (from peripheral venous catheter).	1. january 2018
Primary	Bland and Altman's plot	Mean difference and 95% limits-of-agreement of pO2 (Unit of Measurement: kilopascal) between ABG and aVBG (from peripheral venous catheter).	1. january 2018
Primary	Bland and Altman's plot	Mean difference and 95% limits-of-agreement of pH between ABG and aVBG (from central venous catheter).	1. january 2018
Primary	Bland and Altman's plot	Mean difference and 95% limits-of-agreement of pCO2 (Unit of Measurement: kilopascal) between ABG and aVBG (from central venous catheter).	1. january 2018
Primary	Bland and Altman's plot	Mean difference and 95% limits-of-agreement of pO2 (Unit of Measurement: kilopascal) between ABG and aVBG (from central venous catheter).	1. january 2018
Secondary	Number of patients with sepsis group.	Number and percentage of patients in 'sepsis' group.	1. january 2018
Secondary	Number of patient with metabolic disease	Number and percentage of patients in 'metabolic disease' group.	1. january 2018
Secondary	Number of patient with acute respiratory insufficiency	Number and percentage of patients in 'respiratory disease group' group.	1. january 2018
Secondary	Mean number of days until pH neutrality in sepsis group	Mean number of days until patients ABG pH was within the range 7.35-7.45 in 'sepsis' group.	1. january 2018
Secondary	Mean number of days until pH neutrality in patients with metabolic disease.	Mean number of days until patients ABG pH was within the range 7.35-7.45 in 'metabolic disease' group.	1. january 2018
Secondary	Mean number of days until pH neutrality in patients with respiratory disease.	Mean number of days until patients ABG pH was within the range 7.35-7.45 in 'respiratory disease' group.	1. january 2018