Evaluation of Mathematical Arterialization of Venous Blood in Intensive Care and Pulmonary Ward Patients

Abstract

<b><i>Background:</i></b> Arterial blood gases are important when assessing acute or critically ill patients. Capillary blood and mathematical arterialization of venous blood have been proposed as alternative methods, eliminating pain and complications of arterial puncture. <b><i>Objectives:</i></b> This study compares the arterial samples, arterialized venous samples, and capillary samples in ICU and pulmonary ward patients. <b><i>Method:</i></b> Ninety-one adult patients with respiratory failure were included in the analysis. Arterial, peripheral venous, and mathematically arterialized venous samples were compared in all patients using Bland-Altman analysis, with capillary samples included in 36 patients. <b><i>Results:</i></b> Overall for pH and PCO<sub>2</sub>, arterialized venous values, and in the subset of 36 patients, capillary values, compared well to arterial values and were within the pre-defined clinically acceptable differences (pH ± 0.05 and PCO<sub>2</sub> ± 0.88 kPa). For PO<sub>2</sub>, arterialized or capillary values describe arterial with similar precision (PO<sub>2</sub> arterialized −0.03, LoA −1.48 to 1.42 kPa and PO<sub>2</sub> capillary 0.82, LoA −1.36 to 3 kPa), with capillary values underestimating arterial. <b><i>Conclusions:</i></b> Mathematical arterialization functions well in a range of patients in an ICU and ward outside the country of development of the method. Furthermore, accuracy and precision are similar to capillary blood samples. When considering a replacement for arterial sampling in ward patients, using capillary sampling or mathematical arterialization should depend on logistic ease of implementation and use rather than improved measurements of using either technique.

Comparison of mathematically arterialised venous blood gas sampling with arterial, capillary, and venous sampling in adult patients with hypercapnic respiratory failure: a single-centre longitudinal cohort study

“…Prior studies exploring the agreement between absolute arterial and v-TAC PaCO 2 values indicated a requirement for 41 matched samples at 80% power (β-level 0.20) and 5% significance (α-level 0.05). [8][9][10][11][12][13][14][15] We assumed a proportionate variability for the change in PaCO 2 in the absence of existing data, though aimed to recruit at least 80 patients. In addition to the lack of data, this was because some recruited patients would not require NIV; a review of admissions to our unit in the preceding year showed that 67% of patients assessed were treated with NIV.…”

“…Prior studies exploring the agreement between absolute arterial and v-TAC PaCO 2 values indicated a requirement for 41 matched samples at 80% power (β-level 0.20) and 5% significance (α-level 0.05) 8–15. We assumed a proportionate variability for the change in PaCO 2 in the absence of existing data, though aimed to recruit at least 80 patients.…”

“…Prior studies confirm that v-TAC shows close agreement with ABG for pH and PCO 2 at all ranges, [8][9][10][11][12][13][14][15] though its clinical application is not established. The v-TAC method also shows close agreement with ABG for PO 2 up to 10 kPa, though not for higher oxygen levels.…”

Mathematical Arterialization of Capillary Blood for Blood Gas Analysis in Critically Ill Patients

“…The method uses a mathematical algorithm to transform venous blood gas values to arterialized values (aVBG) by simulating the transport of blood back through the tissue [7]. The method has been investigated in different patient populations, including patients treated in emergency rooms, cardiorespiratory wards, and intensive care units [8][9][10][11]. Thereby, a close agreement between ABG and aVBG for pH (mean difference: 0.002; 95% limits of agreement [LoAs]: −0.025 to 0.029) and pCO 2 has been demonstrated (mean difference: −0.3 mm Hg; 95% LoAs: −4.2 to 3.6 mm Hg) [10].…”

Venous to v-tac™: Challenging the routine use of a traditional ABG

“…It is interesting that a physiological model, derived from first principles without training to data, can in this context behave as well as a statistical model trained to twothirds of these data, and which uses individual clinical variables over and above acidbase and oxygenation status (4). v-tac was previously tested on ICU patients, but using peripheral venous blood (50) where it worked with the same precision as with peripheral venous blood from non-critically ill patients. The reason results were not as expected when tested on central venous blood measured in study III could have been due to various reasons, primarily related to the presence of circulatory disturbances.…”