Metrology part 1: definition of quality criteria

On the assessment of the ability of measurements, nowcasts, and forecasts to track changes

BACKGROUND

Measurements, nowcasts, or forecasts ideally should correctly reflect changes in the values of interest. In this article, we focus on how to assess the ability of measurements, nowcasts, or forecasts to correctly predict the direction of changes in values - which we refer to as the ability to track changes (ATC).

METHODS

We review and develop visual techniques and quantitative measures to assess ATC. Extensions for noisy data and estimation uncertainty are implemented using bootstrap confidence intervals and exclusion areas.

RESULTS

We exemplarily illustrate the proposed methods to assess the ability to track changes for nowcasting during the COVID-19 pandemic, patient admissions to an emergency department, and non-invasive blood pressure measurements. The proposed methods effectively evaluate ATC across different applications.

CONCLUSIONS

The developed ATC assessment methods offer a comprehensive toolkit for evaluating the ATC of measurements, nowcasts, and forecasts. These techniques provide valuable insights into model performance, complementing traditional accuracy measures and enabling more informed decision-making in various fields, including public health, healthcare management, and medical diagnostics.

The FeetMe® Insoles System: Repeatability, Standard Error of Measure, and Responsiveness

BACKGROUND

Three-dimensional motion analysis using optoelectronic cameras and force platforms is typically used to quantify gait disorders. However, these systems have various limitations, particularly when assessing patients in an ecological environment. To address these limitations, several wearable devices have been developed. However, few studies have reported metrological information regarding their repeatability and sensitivity to change.

METHODS

A healthy adult performed 6 min walking tests with FeetMe® system insoles under different walking conditions overground and on a treadmill. The standard error of measurement (SEM), the minimum detectable differences (MDDs), and the effect size (ES) were calculated for spatio-temporal parameters, and the ground reaction force was calculated from the 16,000 steps recorded.

RESULTS

SEM values were below 3.9% for the ground reaction force and below 6.8% for spatio-temporal parameters. ES values were predominantly high, with 72.9% of cases between overground and treadmill conditions with induced asymmetry, and 64.5% of cases between treadmill conditions with and without induced asymmetry exhibiting an ES greater than 1.2. The minimum detectable differences ranged from 4.5% to 10.7% for ground reaction forces and 2.1% to 18.9% for spatio-temporal parameters.

CONCLUSION

Our study demonstrated that the FeetMe® system is a reliable solution. The sensitivity to change showed that these instrumented insoles can effectively reflect patient asymmetry and progress.

Risk factors for poor performance in finger cuff non-invasive monitoring of arterial pressure: A prospective multicenter study

BACKGROUND

Compared to the invasive technique, non-invasive monitoring of arterial pressure favors easier and faster implementation while potentially sacrificing some reliability. This may be particularly true for the Clearsight™ system (Edwards Lifesciences), which enables continuous monitoring. We evaluated the risk factors for its poor performance.

METHODS

Patients with an arterial catheter and stable mean arterial pressure (MAP) over a 5-min period were included. Six pairs of invasive and Clearsight measurements of MAP were collected and the bias between the two techniques was calculated. Poor performance of the Clearsight™ system was defined as either a failure to measure and display MAP or displaying an erroneous MAP (individual bias > 5 mmHg). Fingertip perfusion was assessed using the plethysmographic perfusion index (PI) and the capillary refill time (CRT).

RESULTS

Among 152 ICU patients (MAP of 81 ± 14 mmHg, norepinephrine in 78 [51%]), 78 (51%) experienced a poor performance of the Clearsight™ system: failure to display MAP in 19 (13%) patients, and erroneous value displayed in 59 (44%). In multivariate analysis, PI ≤ 0.85% (adjusted odds ratio [aOR] = 2.94 [95% confidence interval (95%CI):1.34;6.45]), CRT > 4 s (aOR = 5.28 [95%CI 1.39;20.05]), and the presence of hand edema (aOR = 2.06 [95%CI 1.01;4.21]) were associated with a higher likelihood of poor performance. Cardiac arrhythmia (aOR = 1.39 [95%CI 0.64;3.02]) and other tested variables were not associated with poor performance.

CONCLUSIONS

Half of the included patients exhibited poor Clearsight™ system performance. Our results caution against using finger cuff arterial pressure monitoring in patients with low PI (≤0.85%), protracted CRT (>4 s), or hand edema.

REGISTRATION

ClinicalTrials.gov, NCT04269382, Dr. G. Muller, February 13, 2020. https://classic.

CLINICALTRIALS

gov/ct2/show/NCT04269382.

Hemodynamic monitoring in liver transplantation 'the hemodynamic system'

PURPOSE OF REVIEW

The purpose of this article is to provide a comprehensive review of hemodynamic monitoring in liver transplantation.

RECENT FINDINGS

Radial arterial blood pressure monitoring underestimates the aortic root arterial blood pressure and causes excessive vasopressor and worse outcomes. Brachial and femoral artery monitoring is well tolerated and should be considered in critically ill patients expected to be on high dose pressors. The pulmonary artery catheter is the gold standard of hemodynamic monitoring and is still widely used in liver transplantation; however, it is a highly invasive monitor with potential for serious complications and most of its data can be obtained by other less invasive monitors. Rescue transesophageal echocardiography relies on few simple views and should be available as a standby to manage sudden hemodynamic instability. Risk of esophageal bleeding from transesophageal echocardiography in liver transplantation is the same as in other patient populations. The arterial pulse waveform analysis based cardiac output devices are minimally invasive and have the advantage of real-time beat to beat monitoring of cardiac output. No hemodynamic monitor can improve clinical outcomes unless integrated into a goal-directed hemodynamic therapy. The hemodynamic monitoring technique should be tailored to the patient's medical status, surgical technique, and the anesthesiologist's level of expertise.

SUMMARY

The current article provides a review of the current hemodynamic monitoring systems and their integration in goal-directed hemodynamic therapy.

Noninvasive Monitoring of Arterial Pressure: Finger or Lower Leg As Alternatives to the Upper Arm: A Prospective Study in Three ICUs

OBJECTIVES

When the upper arm is inaccessible for measurements of arterial pressure (AP), the best alternative site is unknown. We performed a between-site comparison of the agreement between invasive and noninvasive readings of AP taken at the lower leg, the finger, and the upper arm. The risk associated with measurement errors and the trending ability were also assessed.

DESIGN

Prospective observational study.

SETTING

Three ICUs.

PATIENTS

Patients having an arterial catheter and an arm circumference less than 42 cm.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Three triplicates of AP measurements were collected via an arterial catheter (reference AP), a finger cuff system (ClearSight; Edward Lifesciences, Irvine, CA), and an oscillometric cuff (at the lower leg then the upper arm). Trending ability was assessed through an additional set of measurements after a cardiovascular intervention. The default bed backrest angle was respected. Failure to measure and display AP occurred in 19 patients (13%) at the finger, never at other sites. In 130 patients analyzed, the agreement between noninvasive and invasive readings was worse at the lower leg than that observed at the upper arm or the finger (for mean AP, bias ± sd of 6.0 ± 15.8 vs 3.6 ± 7.1 and 0.1 ± 7.4 mm Hg, respectively; p < 0.05), yielding a higher frequency of error-associated clinical risk (no risk for 64% vs 84% and 86% of measurements, respectively, p < 0.0001). According to the International Organization for Standardization (ISO) 81060-2:2018 standard, mean AP measurements were reliable at the upper arm and the finger, not the lower leg. In 33 patients reassessed after a cardiovascular intervention, both the concordance rate for change in mean AP and the ability to detect a therapy-induced significant change were good and similar at the three sites.

CONCLUSIONS

As compared with lower leg measurements of AP, finger measurements were, when possible, a preferable alternative to upper arm ones.

A new noninvasive finger sensor (NICCI system) for continuous blood pressure and pulse pressure variation monitoring: A method comparison study in patients having neurosurgery

BACKGROUND

The NICCI system (Getinge, Gothenburg, Sweden) is a new noninvasive haemodynamic monitoring system using a finger sensor.

OBJECTIVES

We aimed to investigate the performance of the NICCI system to measure blood pressure and pulse pressure variation compared with intra-arterial measurements.

DESIGN

A prospective method comparison study.

SETTING

University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

PATIENTS

Forty-seven neurosurgery patients.

MAIN OUTCOME MEASURES

We performed a method comparison study in 47 neurosurgery patients to compare NICCI blood pressure measurements (BP NICCI ) with intra-arterial blood pressure measurements (BP ART ) (Bland-Altman analysis, four-quadrant plot, error grid analysis) and NICCI pulse pressure variation measurements (PPV NICCI ) with pulse pressure variation calculated manually from the intra-arterial blood pressure waveform (PPV ART ) (Bland-Altman analysis, predictive agreement, Cohen's kappa).

RESULTS

The mean of the differences ± standard deviation (95% limits of agreement) between BP NICCI and BP ART was 11 ± 10 mmHg (-8 to 30 mmHg) for mean blood pressure (MBP), 3 ± 12 mmHg (-21 to 26 mmHg) for systolic blood pressure (SBP) and 12 ± 10 mmHg (-8 to 31 mmHg) for diastolic blood pressure (DBP). In error grid analysis, 54% of BP NICCI and BP ART MBP measurement pairs were classified as 'no risk', 43% as 'low risk', 3% as 'moderate risk' and 0% as 'significant risk' or 'dangerous risk'. The mean of the differences between PPV NICCI and PPV ART was 1 ± 3% (-4 to 6%). The predictive agreement between PPV NICCI and PPV ART was 80% and Cohen's kappa was 0.55.

CONCLUSIONS

The absolute agreement between BP NICCI and BP ART was not clinically acceptable. We recommend not using the current version of the NICCI system for blood pressure monitoring during surgery. The absolute agreement between PPV NICCI and PPV ART was clinically acceptable with moderate predictive agreement regarding pulse pressure variation categories. The NICCI system needs to be further developed and re-evaluated when an improved version is available.

TRIAL REGISTRATION

The study was registered in the German Clinical Trials Register (DRKS00023188) on 2 October 2020.

A new noninvasive finger sensor (NICCI system) for cardiac output monitoring: A method comparison study in patients after cardiac surgery

BACKGROUND

The new noninvasive finger sensor system NICCI (Getinge; Gothenburg, Sweden) allows continuous cardiac output monitoring. We aimed to investigate its cardiac output measurement performance.

OBJECTIVES

To investigate the NICCI system's cardiac output measurement performance.

DESIGN

Prospective method comparison study.

SETTING

University Medical Center Hamburg-Eppendorf, Hamburg, Germany.

PATIENTS

Fifty-one patients after cardiac surgery.

MAIN OUTCOME MEASURES

We performed a method comparison study in 51 patients after cardiac surgery to compare NICCI cardiac output (CO NICCI ) and NICCI cardiac output calibrated to pulmonary artery thermodilution cardiac output measurement (CO NICCI-CAL ) with pulmonary artery thermodilution cardiac output (CO PAT ). As a secondary analysis we also compared CNAP cardiac output (CO CNAP ) and externally calibrated CNAP cardiac output (CO CNAP-CAL ) with CO PAT .

RESULTS

We analysed 299 cardiac output measurement pairs. The mean of the differences (95% limits of agreement) between CO NICCI and CO PAT was 0.6 (-1.8 to 3.1) l min -1 with a percentage error of 48%. The mean of the differences between CO NICCI-CAL and CO PAT was -0.4 (-1.9 to 1.1) l min -1 with a percentage error of 29%. The mean of the differences between CO CNAP and CO PAT was 1.0 (-1.8 to 3.8) l min -1 with a percentage error of 53%. The mean of the differences between CO CNAP-CAL and CO PAT was -0.2 (-2.0 to 1.6) l min -1 with a percentage error of 35%.

CONCLUSION

The agreement between CO NICCI and CO PAT is not clinically acceptable.

TRIAL REGISTRATION

The study was registered in the German Clinical Trial Register (DRKS00023189) after inclusion of the first patient on October 2, 2020.

Simulation of the Steam Gasification of Japanese Waste Wood in an Indirectly Heated Downdraft Reactor Using PRO/II™: Numerical Comparison of Stoichiometric and Kinetic Models

The conversion of biomass to olefin by employing gasification has recently gained the attention of the petrochemical sector, and syngas composition is a keystone during the evaluation of process design. Process simulation software is a preferred evaluation tool that employs stoichiometric and kinetic approaches. Despite the available literature, the estimation errors of these simulation methods have scarcely been contrasted. This study compares the errors of stoichiometric and kinetic models by simulating a downdraft steam gasifier in PRO/II. The quantitative examination identifies the model that best predicts the composition of products for the gasification of Japanese wood waste. The simulation adopts reaction mechanisms, flowsheet topology, reactions parameters, and component properties reported in the literature. The results of previous studies are used to validate the models in a comparison of the syngas composition and yield of products. The models are used to reproduce gasification at temperatures of 600∼900 °C and steam-to-biomass mass ratios of 0∼4. Both models reproduce experimental results more accurately for changes in the steam-to-biomass mass ratio than for temperature variations. The kinetic model is more accurate for predicting composition and yields, having global errors of 3.91%-mol/mol and 8.16%-g/gBM, respectively, whereas the simple stoichiometric model has an error of 7.96%-mol/mol and 16.21%-g/gBM.

Impact of COVID-19 on the association between pulse oximetry and arterial oxygenation in patients with acute respiratory distress syndrome

Managing patients with acute respiratory distress syndrome (ARDS) requires frequent changes in mechanical ventilator respiratory settings to optimize arterial oxygenation assessed by arterial oxygen partial pressure (PaO₂) and saturation (SaO₂). Pulse oxymetry (SpO₂) has been suggested as a non-invasive surrogate for arterial oxygenation however its accuracy in COVID-19 patients is unknown. In this study, we aimed to investigate the influence of COVID-19 status on the association between SpO₂ and arterial oxygenation. We prospectively included patients with ARDS and compared COVID-19 to non-COVID-19 patients, regarding SpO₂ and concomitant arterial oxygenation (SaO₂ and PaO₂) measurements, and their association. Bias was defined as mean difference between SpO₂ and SaO₂ measurements. Occult hypoxemia was defined as a SpO₂ ≥ 92% while concomitant SaO₂ < 88%. Multiple linear regression models were built to account for confounders. We also assessed concordance between positive end-expiratory pressure (PEEP) trial-induced changes in SpO₂ and in arterial oxygenation. We included 55 patients, among them 26 (47%) with COVID-19. Overall, SpO₂ and SaO₂ measurements were correlated (r = 0.70; p < 0.0001), however less so in COVID-19 than in non-COVID-19 patients (r = 0.55, p < 0.0001 vs. r = 0.84, p < 0.0001, p = 0.002 for intergroup comparison). Bias was + 1.1%, greater in COVID-19 than in non-COVID-19 patients (2.0 vs. 0.3%; p = 0.02). In multivariate analysis, bias was associated with COVID-19 status (unstandardized β = 1.77, 95%CI = 0.38–3.15, p = 0.01), ethnic group and ARDS severity. Occult hypoxemia occurred in 5.5% of measurements (7.7% in COVID-19 patients vs. 3.4% in non-COVID-19 patients, p = 0.42). Concordance rate between PEEP trial-induced changes in SpO₂ and SaO₂ was 84%, however less so in COVID-19 than in non-COVID-19 patients (69% vs. 97%, respectively). Similar results were observed for PaO₂ regarding correlations, bias, and concordance with SpO₂ changes. In patients with ARDS, SpO₂ was associated with arterial oxygenation, but COVID-19 status significantly altered this association.

Existing fluid responsiveness studies using the mini-fluid challenge may be misleading: Methodological considerations and simulations

BACKGROUND

The mini-fluid challenge (MFC) is a clinical concept of predicting fluid responsiveness by rapidly infusing a small amount of intravenous fluids, typically 100 ml, and systematically assessing its haemodynamic effect. The MFC method is meant to predict if a patient will respond to a subsequent, larger fluid challenge, typically another 400 ml, with a significant increase in stroke volume.

METHODS

We critically evaluated the general methodology of MFC studies, with statistical considerations, secondary analysis of an existing study and simulations.

RESULTS

Secondary analysis of an existing study showed that the MFC could predict the total fluid response (MFC + 400 ml) with an area under the receiver operator characteristic curve (AUROC) of 0.92, but that the prediction was worse than random for the response to the remaining 400 ml (AUROC = 0.33). In a null simulation with no response to both the MFC and the subsequent fluid challenge, the commonly used analysis could predict fluid responsiveness with an AUROC of 0.73.

CONCLUSION

Many existing MFC studies are likely overestimating the classification accuracy of the MFC. This should be considered before adopting the MFC into clinical practice. A better study design includes a second, independent measurement of stroke volume after the MFC. This measurement serves as reference for the response to the subsequent fluid challenge.

Devices Used to Measure Force-Time Characteristics of Spinal Manipulations and Mobilizations: A Mixed-Methods Scoping Review on Metrologic Properties and Factors Influencing Use

Background: Spinal manipulations (SMT) and mobilizations (MOB) are interventions commonly performed by many health care providers to manage musculoskeletal conditions. The clinical effects of these interventions are believed to be, at least in part, associated with their force-time characteristics. Numerous devices have been developed to measure the force-time characteristics of these modalities. The use of a device may be facilitated or limited by different factors such as its metrologic properties.

Objectives: This mixed-method scoping review aimed to characterize the metrologic properties of devices used to measure SMT/MOB force-time characteristics and to determine which factors may facilitate or limit the use of such devices within the context of research, education and clinical practice.

Methods: This study followed the Joanna Briggs Institute's framework. The literature search strategy included four concepts: (1) devices, (2) measurement of SMT or MOB force-time characteristics on humans, (3) factors facilitating or limiting the use of devices, and (4) metrologic properties. Two reviewers independently reviewed titles, abstracts and full articles to determine inclusion. To be included, studies had to report on a device metrologic property (e.g., reliability, accuracy) and/or discuss factors that may facilitate or limit the use of the device within the context of research, education or clinical practice. Metrologic properties were extracted per device. Limiting and facilitating factors were extracted and themes were identified.

Results: From the 8,998 studies initially retrieved, 46 studies were finally included. Ten devices measuring SMT/MOB force-time characteristics at the clinician-patient interface and six measuring them at patient-table interfaces were identified. Between zero and eight metrologic properties were reported per device: measurement error (defined as validity, accuracy, fidelity, or calibration), reliability/repeatability, coupling/crosstalk effect, linearity/correlation, sensitivity, variability, drift, and calibration. From the results, five themes related to the facilitating and limiting factors were developed: user-friendliness and versatility, metrologic/intrinsic properties, cost and durability, technique application, and feedback.

Conclusion: Various devices are available to measure SMT/MOB force-time characteristics. Metrologic properties were reported for most devices, but terminology standardization is lacking. The usefulness of a device in a particular context should be determined considering the metrologic properties as well as other potential facilitating and limiting factors.

Parkinson's Disease Patient Monitoring: A Real-Time Tracking and Tremor Detection System Based on Magnetic Measurements

Reliable diagnosis of early-stage Parkinson’s disease is an important task, since it permits the administration of a timely treatment, slowing the progression of the disease. Together with non-motor symptoms, other important signs of disease can be retrieved from the measurement of the movement trajectory and from tremor appearances. To measure these signs, the paper proposes a magnetic tracking system able to collect information about translational and vibrational movements in a spatial cubic domain, using a low-cost, low-power and highly accurate solution. These features allow the usage of the proposed technology to realize a portable monitoring system, that may be operated at home or in general practices, enabling telemedicine and preventing saturation of large neurological centers. Validation is based on three tests: movement trajectory tracking, a rest tremor test and a finger tapping test. These tests are considered in the Unified Parkinson’s Disease Rating Scale and are provided as case studies to prove the system’s capabilities to track and detect tremor frequencies. In the case of the tapping test, a preliminary classification scheme is also proposed to discriminate between healthy and ill patients. No human patients are involved in the tests, and most cases are emulated by means of a robotic arm, suitably driven to perform required tasks. Tapping test results show a classification accuracy of about 93% using a k-NN classification algorithm, while imposed tremor frequencies have been correctly detected by the system in the other two tests.

Agreement between continuous and intermittent pulmonary artery thermodilution for cardiac output measurement in perioperative and intensive care medicine: a systematic review and meta-analysis

BACKGROUND

Pulmonary artery thermodilution is the clinical reference method for cardiac output monitoring. Because both continuous and intermittent pulmonary artery thermodilution are used in clinical practice it is important to know whether cardiac output measurements by the two methods are clinically interchangeable.

METHODS

We performed a systematic review and meta-analysis of clinical studies comparing cardiac output measurements assessed using continuous and intermittent pulmonary artery thermodilution in adult surgical and critically ill patients. 54 studies with 1522 patients were included in the analysis.

RESULTS

The heterogeneity across the studies was high. The overall random effects model-derived pooled estimate of the mean of the differences was 0.08 (95%-confidence interval 0.01 to 0.16) L/min with pooled 95%-limits of agreement of - 1.68 to 1.85 L/min and a pooled percentage error of 29.7 (95%-confidence interval 20.5 to 38.9)%.

CONCLUSION

The heterogeneity across clinical studies comparing continuous and intermittent pulmonary artery thermodilution in adult surgical and critically ill patients is high. The overall trueness/accuracy of continuous pulmonary artery thermodilution in comparison with intermittent pulmonary artery thermodilution is good (indicated by a pooled mean of the differences < 0.1 L/min). Pooled 95%-limits of agreement of - 1.68 to 1.85 L/min and a pooled percentage error of 29.7% suggest that continuous pulmonary artery thermodilution barely passes interchangeability criteria with intermittent pulmonary artery thermodilution. PROSPERO registration number CRD42020159730.

Non-invasive measurement of pulse pressure variation using a finger-cuff method (CNAP system): a validation study in patients having neurosurgery

The finger-cuff system CNAP (CNSystems Medizintechnik, Graz, Austria) allows non-invasive automated measurement of pulse pressure variation (PPV_CNAP). We sought to validate the PPV_CNAP-algorithm and investigate the agreement between PPV_CNAP and arterial catheter-derived manually calculated pulse pressure variation (PPV_INV). This was a prospective method comparison study in patients having neurosurgery. PPV_INV was the reference method. We applied the PPV_CNAP-algorithm to arterial catheter-derived blood pressure waveforms (PPV_INV−CNAP) and to CNAP finger-cuff-derived blood pressure waveforms (PPV_CNAP). To validate the PPV_CNAP-algorithm, we compared PPV_INV−CNAP to PPV_INV. To investigate the clinical performance of PPV_CNAP, we compared PPV_CNAP to PPV_INV. We used Bland–Altman analysis (absolute agreement), Deming regression, concordance, and Cohen's kappa (predictive agreement for three pulse pressure variation categories). We analyzed 360 measurements from 36 patients. The mean of the differences between PPV_INV−CNAP and PPV_INV was −0.1% (95% limits of agreement (95%-LoA) −2.5 to 2.3%). Deming regression showed a slope of 0.99 (95% confidence interval (95%-CI) 0.91 to 1.06) and intercept of −0.02 (95%-CI −0.52 to 0.47). The predictive agreement between PPV_INV−CNAP and PPV_INV was 92% and Cohen’s kappa was 0.79. The mean of the differences between PPV_CNAP and PPV_INV was −1.0% (95%-LoA−6.3 to 4.3%). Deming regression showed a slope of 0.85 (95%-CI 0.78 to 0.91) and intercept of 0.10 (95%-CI −0.34 to 0.55). The predictive agreement between PPV_CNAP and PPV_INV was 82% and Cohen’s kappa was 0.48. The PPV_CNAP-algorithm reliably calculates pulse pressure variation compared to manual offline pulse pressure variation calculation when applied on the same arterial blood pressure waveform. The absolute and predictive agreement between PPV_CNAP and PPV_INV are moderate.

Non-invasive measurement of pulse pressure variation using a finger-cuff method in obese patients having laparoscopic bariatric surgery

Pulse pressure variation (PPV) is a dynamic cardiac preload variable used to predict fluid responsiveness. PPV can be measured non-invasively using innovative finger-cuff systems allowing for continuous arterial pressure waveform recording, e.g., the Nexfin system [BMEYE B.V., Amsterdam, The Netherlands; now Clearsight (Edwards Lifesciences, Irvine, CA, USA)] (PPV_Finger). However, the agreement between PPV_Finger and PPV derived from an arterial catheter (PPV_ART) in obese patients having laparoscopic bariatric surgery is unknown. We compared PPV_Finger and PPV_ART at 6 time points in 60 obese patients having laparoscopic bariatric surgery in a secondary analysis of a prospective method comparison study. We used Bland–Altman analysis to assess absolute agreement between PPV_Finger and PPV_ART. The predictive agreement for fluid responsiveness between PPV_Finger and PPV_ART was evaluated across three PPV categories (PPV < 9%, PPV 9–13%, PPV > 13%) as concordance rate of paired measurements and Cohen’s kappa. The overall mean of the differences between PPV_Finger and PPV_ART was 0.5 ± 4.6% (95%-LoA − 8.6 to 9.6%) and the overall predictive agreement was 72.4% with a Cohen’s kappa of 0.53. The mean of the differences was − 0.7 ± 3.8% (95%-LoA − 8.1 to 6.7%) without pneumoperitoneum in horizontal position and 1.1 ± 4.8% (95%-LoA − 8.4 to 10.5%) during pneumoperitoneum in reverse-Trendelenburg position. The absolute agreement and predictive agreement between PPV_Finger and PPV_ART are moderate in obese patients having laparoscopic bariatric surgery.