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

Challenges in harmonizing immunoassays: The use of the Bland-Altman based harmonization algorithm

BACKGROUND

In this study, we compared the recently proposed Bland-Altman plot-based harmonization algorithm (BA-BHA) with the weighted Deming regression-based harmonization algorithm (WD-BHA) taken as an example in ISO 21151:2020, aiming to evaluate the effectiveness of BA-BHA and discuss the applicability of these two different harmonization algorithms.

METHODS

BA-BHA and WD-BHA were applied to 19 measurands on LiCA medical devices, Chemclin Diagnostics Co., Ltd. A panel of 80 patient sera were collected for each measurand and the effectiveness of BA-BHA and the applicability of the two different harmonization algorithms were specified according to the Bland-Altman (B-A) plot, curve estimation and the Passing-Bablok regression.

RESULTS

After harmonized with BA-BHA, the mean of the B-A plot for each measurand was close to zero, and the limits of agreement (LoAs) met the quality requirements. The distribution of the variations in the B-A plot was demonstrated approximately symmetric over the measuring interval. Furthermore, "0" was included in the 95% confidence interval of the intercept and "1" was included in the 95% confidence interval of the slope for the Passing-Bablok regression, indicating acceptable harmonization effects for all 19 measurands. In contrast, acceptable harmonization effects were achieved in only some of the 19 measurands.

CONCLUSION

Acceptable harmonization effects can be achieved for various measurands by BA-BHA because both the mean and the distribution of percent differences in the B-A plot can be adjusted, which demonstrating BA-BHA with a more extensive applicability compared to WD-BHA.

Sleep-Disordered Breathing in Patients with Chronic Heart Failure and Its Implications on Real-Time Hemodynamic Regulation, Baroreceptor Reflex Sensitivity, and Survival

Background: Impairment in autonomic activity is a prognostic marker in patients with heart failure (HF), and its involvement has been suggested in cardiovascular complications of obstructive sleep apnea syndrome (OSAS) and Cheyne-Stokes respiration (CSR). This prospective observational study aims to investigate the implications of sleep-disordered breathing (SDB) on hemodynamic regulation and autonomic activity in chronic HF patients. Methods: Chronic HF patients, providing confirmation of reduced ejection fraction (≤35%), underwent polysomnography, real-time hemodynamic, heart rate variability (HRV), and baroreceptor reflex sensitivity (BRS) assessments using the Task Force Monitor. BRS was assessed using the sequencing method during resting conditions and stress testing. Results: Our study population (n = 58) was predominantly male (41 vs. 17), with a median age of 61 (±11) yrs and a median BMI of 30 (±5) kg/m2. Patients diagnosed with CSR were 13.8% (8/58) and 50.0% (29/58) with OSAS. No differences in the real-time assessment of hemodynamic regulation, heart rate variability, or baroreceptor reflex function were found between patients with OSAS, CSR, and patients without SDB. A subgroup analysis of BRS and HRV in patients with severe SDB (AHI > 30/h) and without SDB (AHI < 5) revealed numerically reduced BRS and increased LF/HF-RRI values under resting conditions, as well as during mental testing in patients with severe SDB. Patients with moderate-to-severe SDB had a shorter overall survival, which was, however, dependent upon age. Conclusions: Chronic HF patients with severe SDB may exhibit lower baroreceptor function and impaired cardiovascular autonomic function in comparison with HF patients without SDB.

Haemodynamic monitoring during noncardiac surgery: past, present, and future

During surgery, various haemodynamic variables are monitored and optimised to maintain organ perfusion pressure and oxygen delivery - and to eventually improve outcomes. Important haemodynamic variables that provide an understanding of most pathophysiologic haemodynamic conditions during surgery include heart rate, arterial pressure, central venous pressure, pulse pressure variation/stroke volume variation, stroke volume, and cardiac output. A basic physiologic and pathophysiologic understanding of these haemodynamic variables and the corresponding monitoring methods is essential. We therefore revisit the pathophysiologic rationale for intraoperative monitoring of haemodynamic variables, describe the history, current use, and future technological developments of monitoring methods, and finally briefly summarise the evidence that haemodynamic management can improve patient-centred outcomes.

Pulse Pressure Variance (PPV)-Guided Fluid Management in Adult Patients Undergoing Supratentorial Tumor Surgeries: A Randomized Controlled Trial

Objective  Appropriate fluid management in neurosurgery is critical due to the risk of secondary brain injury. Determination of volume status is challenging with static variables being unreliable. Goal-directed fluid therapy with dynamic variables allows reliable determination of fluid responsiveness and promises better outcomes. We aimed to compare the intraoperative fluid requirement between conventional central venous pressure (CVP)-guided and pulse pressure variance (PPV)-guided fluid management in supratentorial tumor surgeries. Materials and Methods  This prospective, randomized, double-blind, single-center trial was conducted with 72 adults undergoing supratentorial tumor surgery in a supine position. Patients were divided into two groups of 36 patients each receiving CVP- and PPV-guided fluid therapy. The CVP-guided group received boluses to target CVP greater than 8 mm Hg along with hourly replacement of intraoperative losses and maintenance fluids. The PPV-guided group received boluses to target PPV less than 13% in addition to maintenance fluids. Total intraoperative fluids administered and the incidence of hypotension was recorded along with the brain relaxation score. Postoperatively, serum lactate levels, periorbital and conjunctival edema, as well as postoperative nausea and vomiting were assessed. Statistical Analyses  All statistical analyses were performed with Statistical Package for Social Sciences, version-20 (SPSS-20, IBM, Chicago, Illinois, United States). To compare the means between the two groups (CVP vs. PPV), independent samples t -test was used for normal distribution data and Mann-Whitney U test for nonnormal distribution data. The chi-square test or Fischer's exact test was used for categorical variables. Results  The CVP group received significantly more intraoperative fluids than the PPV group (4,340 ± 1,010 vs. 3,540 ± 740 mL, p  < 0.01). Incidence of hypotension was lower in the PPV group (4 [11.1%] vs. 0 [0%], p  = 0.04). Brain relaxation scores, serum lactate levels, periorbital and conjunctival edema, and incidence of postoperative nausea and vomiting were comparable between the groups. Conclusion  The requirement for intraoperative fluids was less in PPV-guided fluid management with better hemodynamic stability, adequate brain conditions, and no compromise of perfusion.

Noninvasive Assessment of Arterial Pulse-Pressure Variation During General Anesthesia: Clinical Evaluation of a New High-Fidelity Upper Arm Cuff

OBJECTIVES

To compare noninvasive pulse-pressure variation (PPV) measurements obtained from a new high-fidelity upper arm cuff using a hydraulic coupling technique to corresponding intraarterial PPV measurements.

DESIGN

The authors used prospective multicenter comparison and development studies for the new high-fidelity upper arm cuff.

SETTING

The study was performed in the departments of Anesthesiology at the Ludwig-Maximilians-Universität München Hospital, the University Hospital of Bonn, and the RoMed Hospital in Rosenheim (all Germany).

PARTICIPANTS

A total of 153 patients were enrolled, undergoing major abdominal surgery or neurosurgery with mechanical ventilation. For the evaluation of PPV, 1,467 paired measurements in 107 patients were available after exclusion due to predefined quality criteria.

INTERVENTIONS

Simultaneous measurements of PPV were performed from a reference femoral arterial catheter (PPV_ref) and the high-fidelity upper arm cuff (PPV_cuff). The new device uses a semirigid conical shell. It incorporates a hydraulic sensor pad with a pressure transducer, leading to a tissue pressure-pulse contour with all characteristics of an arterial- pulse contour.

MEASUREMENTS AND MAIN RESULTS

The comparative analysis of the included measurements showed that PPV_ref and PPV_cuff were closely correlated (r = 0.92). The mean of the differences between PPV_ref and PPV_cuff was 0.1 ± 2.0%, with 95% limits of agreement between -4.1% and 3.9%. To track absolute changes in PPV >2%, the concordance rate between the 2 methods was 93%.

CONCLUSIONS

The new high-fidelity upper arm cuff method provided a clinically reliable estimate of PPV.

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.