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Shastri L, Thomsen LP, Toftegaard M, Tygesen GB, Weinreich UM, Rychwicka-Kielek BA, Davies MG, Ekström M, Rittger H, Kelly AM, Kristensen SR, Kjærgaard S, Kamperidis P, Manuel A, Damgaard KA, Andreassen S, Rees SE. The use of venous blood gas in assessing arterial acid-base and oxygenation status - an analysis of aggregated data from multiple studies evaluating the venous to arterial conversion (v-TAC) method. Expert Rev Respir Med 2024:1-7. [PMID: 38973767 DOI: 10.1080/17476348.2024.2378021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Accepted: 07/05/2024] [Indexed: 07/09/2024]
Abstract
BACKGROUND Several methods exist to reduce the number of arterial blood gases (ABGs). One method, Roche v-TAC, has been evaluated in different patient groups. This paper aggregates data from these studies, in different patient categories using common analysis criteria. RESEARCH DESIGN AND METHODS We included studies evaluating v-TAC based on paired arterial and peripheral venous blood samples. Bland-Altman analysis compared measured and calculated arterial values of pH, PCO2, and PO2. Subgroup analyses were performed for normal, chronic hypercapnia and chronic base excess, acute hyper- and hypocapnia, and acute and chronic base deficits. RESULTS 811 samples from 12 studies were included. Bias and limits of agreement for measured and calculated values: pH 0.001 (-0.029 to 0.031), PCO2 -0.08 (-0.65 to 0.49) kPa, and PO2 0.04 (-1.71 to 1.78) kPa, with similar values for all sub-group analyses. CONCLUSION These data suggest that v-TAC analysis may have a role in replacing ABGs, avoiding arterial puncture. Substantial data exist in patients with chronic hypercapnia and chronic base excess, acute hyper- and hypocapnia, and in patients with relatively normal acid-base status, with similar bias and precision across groups and across study data. Limited data exist for patients with acute and chronic base deficits.
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Affiliation(s)
- Lisha Shastri
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | | | | | - Gitte Boier Tygesen
- Department of Emergency Medicine, Aarhus University Hospital, Aarhus, Denmark
| | - Ulla Møller Weinreich
- Department of Lung Medicine, Aalborg University Hospital, Aalborg, Denmark
- The Clinical Institute, Aalborg University, Aalborg, Denmark
| | - Beate Agnieszka Rychwicka-Kielek
- The Clinical Institute, Aalborg University, Aalborg, Denmark
- Bronchoskopic Diagnostics Department, Mazowieckie Centrum Leczenia Chorób Płuc i Gruźlicy, Otwock, Poland
| | - Michael Gordon Davies
- Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Magnus Ekström
- Medicine, Department of Clinical Sciences Lund, Respiratory Medicine, Allergology and Palliative Medicine, Lund University, Lund, Sweden
| | - Harald Rittger
- Klinikum Fürth, Department of Cardiology, Fürth, Germany
| | - Anne-Maree Kelly
- Joseph Epstein Centre for Emergency Medicine Research, Western Health, Sunshine hospital, Melbourne, Australia
- Department of Medicine, Western Health, Melbourne Medical School, The University of Melbourne, Parkville, Australia
| | - Søren Risom Kristensen
- The Clinical Institute, Aalborg University, Aalborg, Denmark
- Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark
| | - Søren Kjærgaard
- Department of Anesthesiology and Intensive Care, Aalborg University Hospital North, Aalborg, Denmark
| | | | - Ari Manuel
- Sleep and Respiratory Department, University Hospital Aintree, Liverpool, UK
| | | | - Steen Andreassen
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - Stephen Edward Rees
- Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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Davies MG, Wozniak DR, Quinnell TG, Palas E, George S, Huang Y, Jayasekara R, Stoneman V, Smith IE, Thomsen LP, Rees SE. 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. BMJ Open Respir Res 2023; 10:e001537. [PMID: 37369550 DOI: 10.1136/bmjresp-2022-001537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 06/16/2023] [Indexed: 06/29/2023] Open
Abstract
BACKGROUND Accurate arterial blood gas (ABG) analysis is essential in the management of patients with hypercapnic respiratory failure, but repeated sampling requires technical expertise and is painful. Missed sampling is common and has a negative impact on patient care. A newer venous to arterial conversion method (v-TAC, Roche) uses mathematical models of acid-base chemistry, a venous blood gas sample and peripheral blood oxygen saturation to calculate arterial acid-base status. It has the potential to replace routine ABG sampling for selected patient cohorts. The aim of this study was to compare v-TAC with ABG, capillary and venous sampling in a patient cohort referred to start non-invasive ventilation (NIV). METHODS Recruited patients underwent near simultaneous ABG, capillary blood gas (CBG) and venous blood gas (VBG) sampling at day 0, and up to two further occasions (day 1 NIV and discharge). The primary outcome was the reliability of v-TAC sampling compared with ABG, via Bland-Altman analysis, to identify respiratory failure (via PaCO2) and to detect changes in PaCO2 in response to NIV. Secondary outcomes included agreements with pH, sampling success rates and pain. RESULTS The agreement between ABG and v-TAC/venous PaCO2 was assessed for 119 matched sampling episodes and 105 between ABG and CBG. Close agreement was shown for v-TAC (mean difference (SD) 0.01 (0.5) kPa), but not for CBG (-0.75 (0.69) kPa) or VBG (+1.00 (0.90) kPa). Longitudinal data for 32 patients started on NIV showed the closest agreement for ABG and v-TAC (R2=0.61). v-TAC sampling had the highest first-time success rate (88%) and was less painful than arterial (p<0.0001). CONCLUSION Mathematical arterialisation of venous samples was easier to obtain and less painful than ABG sampling. Results showed close agreement for PaCO2 and pH and tracked well longitudinally such that the v-TAC method could replace routine ABG testing to recognise and monitor patients with hypercapnic respiratory failure. TRIAL REGISTRATION NUMBER NCT04072848; www. CLINICALTRIALS gov.
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Affiliation(s)
- Michaael Gordon Davies
- Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Dariusz Rafal Wozniak
- Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Timothy George Quinnell
- Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Earl Palas
- Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Susan George
- Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Yingchang Huang
- Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Ruwanthi Jayasekara
- Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Victoria Stoneman
- Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
| | - Ian Edward Smith
- Respiratory Support and Sleep Centre, Royal Papworth Hospital NHS Foundation Trust, Cambridge, UK
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Mathematically arterialised venous blood is a stable representation of patient acid-base status at steady state following acute transient changes in ventilation. J Clin Monit Comput 2021; 36:1333-1340. [PMID: 34647198 PMCID: PMC8513560 DOI: 10.1007/s10877-021-00764-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 10/05/2021] [Indexed: 11/22/2022]
Abstract
Hyper- or hypoventilation are commonly occurring stress responses to arterial puncture around the time of blood sampling and have been shown to rapidly alter arterial blood acid–base parameters. This study aimed to evaluate a physiology-based mathematical method to transform peripheral venous blood acid–base values into mathematically arterialised equivalents following acute, transient changes in ventilation. Data from thirty patients scheduled for elective surgery were analysed using the physiology-based method. These data described ventilator changes simulating ‘hyper-’ or ‘hypoventilation’ at arterial puncture and included acid–base status from simultaneously drawn blood samples from arterial and peripheral venous catheters at baseline and following ventilatory change. Venous blood was used to calculate mathematically arterialised equivalents using the physiology-based method; baseline values were analysed using Bland–Altman plots. When compared to baseline, measured arterial and calculated arterialised values at each time point within limits of pH: ± 0.03 and PCO2: ± 0.5 kPa, were considered ‘not different from baseline’. Percentage of values considered not different from baseline were calculated at each sampling timepoint following hyper- and hypoventilation. For the physiological method, bias and limits of agreement for pH and PCO2 were -0.001 (-0.022 to 0.020) and -0.02 (-0.37 to 0.33) kPa at baseline, respectively. 60 s following a change in ventilation, 100% of the mathematically arterialised values of pH and PCO2 were not different from baseline, compared to less than 40% of the measured arterial values at the same timepoint. In clinical situations where transient breath-holding or hyperventilation may compromise the accuracy of arterial blood samples, arterialised venous blood is a stable representative of steady state arterial blood.
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Weber M, Cave G. Trending peripheral venous PCO 2 in patients with respiratory failure using mathematically arterialised venous blood gas samples. BMJ Open Respir Res 2021; 8:8/1/e000896. [PMID: 34049866 PMCID: PMC8166602 DOI: 10.1136/bmjresp-2021-000896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 05/11/2021] [Indexed: 11/10/2022] Open
Abstract
Background Trending venous blood gases (VBGs) has been suggested as an alternative to arterial blood gases (ABGs) in patients with respiratory failure, but there are limits to its utility. The aim of this study was to compare the trending of venous carbon dioxide partial pressure (pCO2) (pCO2v) with mathematically arterialised pCO2 (pCO2ca) and to further evaluate whether pCO2ca follows change in arterial pCO2 (pCO2a) more accurately. Methods We analysed two data sets. The first was a retrospective study of patients with respiratory failure admitted to the intensive care unit. Venous samples were mathematically arterialised using the vTAC method. The change in pCO2 between two consecutive samples (ΔpCO2) for pCO2v was compared with the change in calculated pCO2ca values. In the second data set taken from previously published work, we analysed 82 trend points (difference between consecutive samples) for change in pCO2. There were pCO2v, pCO2a and pCO2ca values for each trend point. The primary outcome measures were the 95% limits of agreement (LOAs) between different sampling methods for ΔpCO2. Results In the first data set, 46 patients had 203 VBG results giving 157 trend points for ΔpCO2 analysis. The 95% LOAs for ΔpCO2ca and ΔpCO2v were −9.28 to 11.12 mm Hg. In the second data set, 95% LOAs for ΔpCO2 were −9.46 to 9.48 mm Hg for ΔpCO2a and ΔpCO2v, −8.94 to 8.58 mm Hg for ΔpCO2ca and ΔpCO2v, and −4.54 to 4.91 mm Hg for ΔpCO2a and ΔpCO2ca. Conclusion This study suggests that trending pCO2v is not an accurate way to trend pCO2a in patients with respiratory failure. ΔpCO2ca via vTAC trended differently to ΔpCO2v. Our data suggest pCO2ca more accurately trends pCO2a.
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Affiliation(s)
- Merle Weber
- Intensive Care Unit, Hawke's Bay District Health Board, Hastings, Hawke's Bay, New Zealand
| | - Grant Cave
- Intensive Care Unit, Hawke's Bay District Health Board, Hastings, Hawke's Bay, New Zealand
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Shastri L, Boulain T, Rees SE, Thomsen LP. Comparison of two methods for converting central venous values of acid-base status to arterial values in critically ill patients. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 203:106022. [PMID: 33713960 DOI: 10.1016/j.cmpb.2021.106022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 02/19/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Assessment of the critically ill patient requires arterial acid-base status. Venous blood could provide a surrogate, with methods transforming venous values to arterial, improving their utility. This manuscript compares two of these methods, a statistical and a physiological method. Where these methods are inadequate to describe critically ill patients, physiological mechanisms are explored to explain discrepancies. METHODS 1109 paired arterial and central-venous blood samples, from patients diagnosed with acute circulatory failure, were available for retrospective analysis. Of these, 386 samples were used previously to validate the statistical model. The statistical method of Boulain et al. 2016 and the physiological method of Rees et al. 2006 were applied to the 386 sample pairs, and compared using Bland-Altman analysis. A subset of the 1109 samples, where the physiological method could not accurately calculate arterial values, were analysed further to assess the necessary addition of CO2 or strong acid at the tissues to account for arterio-venous differences. RESULTS Bias (LoA) for comparison of calculated and measured arterial values (n = 386) were similar for the statistical method (pH: -0.003 (-0.051 to 0.045), PCO2: -0.02 (-1.33 to 1.29 kPa)) and physiological method (pH: 0.009 (-0.033 to 0.052), PCO2: -0.08 (-1.20 to 1.03 kPa)). In the 381 cases (of the 1109 sample pairs) defined as not accurately described, addition of a median CO2 concentration of 0.72 mmol/l in excess of aerobic metabolism, explained this for 333 cases, with the remainder requiring simultaneous strong acid transport. CONCLUSION Both methods appear equal in their ability to transform central-venous values to arterial, albeit warranting caution when using either in a critically ill population. The physiological approach was able to describe arterio-venous differences not explained by aerobic metabolism alone.
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Affiliation(s)
- Lisha Shastri
- Respiratory and Critical Care Group, Aalborg University, Denmark.
| | - Thierry Boulain
- Medical-Surgical Intensive Care Unit, Regional Hospital Centre, France; Clinical Research in Intensive Care and Sepsis Group (CRICS-TRIGGERSEP), www.triggersep.org, France
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