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

NCT ID: NCT03309423

Last Updated: 2017-10-13

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

UNKNOWN

Total Enrollment

50 participants

Study Classification

OBSERVATIONAL

Study Start Date

2017-10-09

Study Completion Date

2018-03-30

Brief Summary

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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.

Detailed Description

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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.

Conditions

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Respiratory Insufficiency Metabolic Disease Acidosis Alkalosis Sepsis Abdomen, Acute

Keywords

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Blood gas analysis Critical care venus to arterial conversion

Study Design

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Observational Model Type

CASE_ONLY

Study Time Perspective

PROSPECTIVE

Study Groups

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Respiratory disease

Patients with acute respiratory insufficiency admitted to the ICU and with pH \<7,35 or \>7,45

venous to arterial conversion (v-TAC)

Intervention Type DIAGNOSTIC_TEST

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.

Metabolic disease

Patients with acute metabolic disease admitted to the ICU and with pH \<7,35 or \>7,45

venous to arterial conversion (v-TAC)

Intervention Type DIAGNOSTIC_TEST

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.

Sepsis

Patients with acute sepsis admitted to the ICU and with pH \<7,35 or \>7,45

venous to arterial conversion (v-TAC)

Intervention Type DIAGNOSTIC_TEST

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.

Interventions

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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.

Intervention Type DIAGNOSTIC_TEST

Eligibility Criteria

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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.
Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Regionshospital Nordjylland

OTHER_GOV

Sponsor Role collaborator

Aalborg University

OTHER

Sponsor Role lead

Responsible Party

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Mads Lumholdt

Principal investigator

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Peter Leutscher

Role: STUDY_DIRECTOR

Professor, Center for Clinical Research

Locations

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Faculty of Medicine, Doctoral School, Ph.d. study

Aalborg, North Denmark, Denmark

Site Status RECRUITING

Countries

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Denmark

Central Contacts

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Mads Lumholdt

Role: CONTACT

Phone: +45 51914156

Email: [email protected]

Kjeld Damgaard

Role: CONTACT

Phone: +45 51914156

Email: [email protected]

Facility Contacts

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Christina Elmer, Secretary

Role: primary

Other Identifiers

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v-TAC-ICU

Identifier Type: -

Identifier Source: org_study_id