Continuous Non-invasive Arterial Pressure Research Articles

Continuous non-invasive vs. invasive arterial blood pressure monitoring during neuroradiological procedure: a comparative, prospective, monocentric, observational study

BackgroundIn the perioperative setting, the most accurate way to continuously measure arterial blood pressure (ABP) is using an arterial catheter. Surrogate methods such as finger cuff have been developed to allow non-invasive measurements and are increasingly used, but need further evaluation. The aim of this study is to evaluate the accuracy and clinical concordance between two devices for the measurement of ABP during neuroradiological procedure.MethodsThis is a prospective, monocentric, observational study. All consecutive patients undergoing a neuroradiological procedure were eligible. Patients who needed arterial catheter for blood pressure measurement were included. During neuroradiological procedure, ABP (systolic, mean and diatolic blood pressure) was measured with two different technologies: radial artery catheter and Nexfin. Bland-Altman and error grid analyses were performed to evaluate the accuracy and clinical concordance between devices.ResultsFrom March 2022 to November 2022, we included 50 patients, mostly ASA 3 (60%) and required a cerebral embolization (94%) under general anaesthesia (96%). Error grid analysis showed that 99% of non-invasive ABP measures obtained with the Nexfin were located in the risk zone A or B. However, 65.7% of hypertension events and 41% of hypotensive events were respectively not detected by Nexfin. Compared to the artery catheter, a significant relationship was found for SAP (r2 = 0.78) and MAP (r2 = 0.80) with the Nexfin (p < 0.001). Bias and limits of agreement (LOA) were respectively 9.6 mmHg (− 15.6 to 34.8 mmHg) and − 0.8 mmHg (− 17.2 to 15.6 mmHg), for SAP and MAP.ConclusionsNexfin is not strictly interchangeable with artery catheter for ABP measuring. Further studies are needed to define its clinical use during neuroradiological procedure.Trial registrationClinicaltrials.gov, registration number: NCT05283824.

Post-anesthesia care unit hypotension in low-risk patients recovering from non-cardiac surgery: a prospective observational study.

Intraoperative hypotension is common and associated with organ injury. Hypotension can not only occur during surgery, but also thereafter. After surgery, most patients are treated in post-anesthesia care units (PACU). The incidence of PACU hypotension is largely unknown - presumably in part because arterial pressure is usually monitored intermittently in PACU patients. We therefore aimed to evaluate the incidence, duration, and severity of PACU hypotension in low-risk patients recovering from non-cardiac surgery. In this observational study, we performed blinded continuous non-invasive arterial pressure monitoring with finger-cuffs (ClearSight system; Edwards Lifesciences, Irvine,CA, USA) in 100 patients recovering from non-cardiac surgery in the PACU. We defined PACU hypotension as a mean arterial pressure (MAP) < 65 mmHg. Patients had continuous finger-cuff monitoring for a median (25th percentile, 75th percentile) of 64 (44 to 91) minutes. Only three patients (3%) had PACU hypotension for at least one consecutive minute. These three patients had 4, 4, and 2 cumulative minutes of PACU hypotension; areas under a MAP of 65 mmHg of 17, 9, and 9 mmHg x minute; and time-weighted averages MAP less than 65 mmHg of 0.5, 0.3, and 0.2 mmHg. The median volume of crystalloid fluid patients were given during PACU treatment was 200 (100 to 400) ml. None was given colloids or a vasopressor during PACU treatment. In low-risk patients recovering from non-cardiac surgery, the incidence of PACU hypotension was very low and the few episodes of PACU hypotension were short and of modest severity.

Early Physiologic Numerical and Waveform Characteristics of Simulated Hemorrhagic Events With Healthy Volunteers Donating Blood.

Early signs of bleeding are often masked by the physiologic compensatory responses delaying its identification. We sought to describe early physiologic signatures of bleeding during the blood donation process. Waveform-level vital sign data including electrocardiography, photoplethysmography (PPG), continuous noninvasive arterial pressure, and respiratory waveforms were collected before, during, and after bleeding. Fifty-five healthy volunteers visited blood donation center to donate whole blood. After obtaining the informed consent, 3 minutes of resting time was given to each subject. Then 3 minutes of orthostasis was done, followed by another 3 minutes of resting before the blood donation. After the completion of donating blood, another 3 minutes of postbleeding resting time, followed by 3 minutes of orthostasis period again. From 55 subjects, waveform signals as well as numerical vital signs (heart rate [HR], respiratory rate, blood pressure) and clinical characteristics were collected, and data from 51 subjects were analyzable. Any adverse events (AEs; dizziness, lightheadedness, nausea) were documented. Statistical and physiologic features including HR variability (HRV) metrics and other waveform morphologic parameters were modeled. Feature trends for all participants across the study protocol were analyzed. No significant changes in HR, blood pressure, or estimated cardiac output were seen during bleeding. Both orthostatic challenges and bleeding significantly decreased time domain and high-frequency domain HRV, and PPG amplitude, whereas increasing PPG amplitude variation. During bleeding, time-domain HRV feature trends were most sensitive to the first 100 mL of blood loss, and incremental changes of different HRV parameters (from 300 mL of blood loss), as well as a PPG morphologic feature (from 400 mL of blood loss), were shown with statistical significance. The AE group (n = 6) showed decreased sample entropy compared with the non-AE group during postbleed orthostatic challenge (p = 0.003). No significant other trend differences were observed during bleeding between AE and non-AE groups. Various HRV-related features were changed during rapid bleeding seen within the first minute. Subjects with AE during postbleeding orthostasis showed decreased sample entropy. These findings could be leveraged toward earlier identification of donors at risk for AE, and more broadly building a data-driven hemorrhage model for the early treatment of critical bleeding.

Continuous non-invasive arterial blood pressure monitoring with photoplethysmography via SE-MSResUNet network

ObjectiveArterial blood pressure (ABP) waveforms include physiological parameters closely related to BP values, while only a few studies predict BP values through the monitoring ABP waveforms. Current ABP waveforms monitoring methods are limited by its high computing cost and information redundancy of multi-channel input signals. The aim of our work is to propose a new end-to-end method for monitoring the ABP waveforms using single-channel photoplethysmography (PPG) signals by constructing a lightweight Multi-Scale Residual U-Net fused with Squeeze-and-Excitation module (SE-MSResUNet) model. MethodsFirstly, the PPG and ABP signals are preprocessed with denoising, segmentation, and eliminating phase difference. Subsequently, the SE-MSResUNet model is constructed and trained using training data to achieve the mapping relationship between PPG and ABP signals. Then, the BP values are extracted from the monitored ABP waveforms. Finally, the performance of the SE-MSResUNet in ABP waveform monitoring and BP estimation is investigated. ResultsThe ABP waveforms monitored by our proposed SE-MSResUNet network with PPG signals only are highly consistent with the reference ABP waveforms. The MAE ± SD of estimated diastolic blood pressure (DBP), mean arterial pressure (MAP) and systolic blood pressure (SBP) compared with reference values are 2.16 ± 3.75, 2.29 ± 3.72, and 3.88 ± 6.17 mmHg, respectively. The proposed method meets the Association for the Advancement of Medical Instrumentation (AAMI) standard and reach A level of the British Hypertension Society (BHS) standard. ConclusionsOur proposed method outperforms current state-of-the-art methods for non-invasive blood pressure monitoring from PPG signals. The algorithm provides a potential possibility for continuous non-invasive blood pressure monitoring through portable wearable devices.

Agreement of continuous non-invasive arterial blood pressure monitoring (CNAP) and pulmonary artery catheter thermodilution method in estimating the hemodynamic parameters of post CABG patients

Abstract Background The use of hemodynamic parameters in monitoring patients after coronary artery bypass surgery is an essential element of clinical practice. It helps intensivist and physicians to properly manage patients after surgery where hemodynamic parameters are usually dynamic and complicated. Pulmonary artery guided thermodilution (PACT) has been the gold standard in assessing the adequacy of cardiac output, however, its invasive nature is also associated with more complex procedures and the risk of complications, including infections. With the emergence of new non-invasive hemodynamic monitoring devices such as the CNAP (continuous non-invasive arterial pressure), alternative methods for hemodynamic monitoring is now possible. Compared to invasive methods, it is easier to use with an error-free application, safer, less risk of infection and more cost effective. Purpose To determine the agreement of Continuous non-invasive arterial pressure (CNAP) and pulmonary artery guided thermodilution in monitoring the hemodynamic parameters of patients who underwent coronary artery bypass graft surgery. Methods This is a cross-sectional study conducted at the cardiovascular surgical intensive care unit and included 63 patients with Coronary artery disease who underwent elective coronary artery bypass graft surgery. Cardiac output, Cardiac Index, Stroke volume and Systemic vascular resistance were simultaneously obtained using both the CNAP and PACT. Three consecutive sets of measurements were recorded for each patient with a 3 hour interval; during arrival at the ICU, 3 hours post op, and 6 hours post op. Results The mean difference between PACT-CO and CNAP-CO was -0.81 L/min (SD -1.18 to -0.44) with a 95% limits of agreement of -3.74 to 2.11 L/min on the 0 hour, -0.81L/min (SD -1.22 to -0.41) with a 95% limits of agreement of -1.98 to 1.18 L/min on the 3rd hour, and -0.77L/min (SD -1.08 to -0.46) with a 95% limits of agreement of -3.22 to 1.68 L/min on the 6th hour post op. The results showed a significant difference between the PACT and CNAP. However, a positive correlation was noted between PACT-CO and CNAP-CO, the correlation coefficient on the 0, 3rd and 6th hour were 0.5384, 0.5158, and 0.6265 respectively. Conclusion CNAP derived hemodynamic parameters had a high mean difference compared to the PACT and there was no agreement between the two methods. However, it was able to have a positive correlation with the PACT, making it possible for the CNAP to track the hemodynamic changes during the post operative course.

Impaired cerebrovascular reactivity correlates with reduced retinal vessel density in patients with carotid artery stenosis: Cross-sectional, single center study.

The cerebral and retinal circulation systems are developmentally, anatomically, and physiologically interconnected. Thus, we hypothesized that hypoperfusion due to atherosclerotic stenosis of the internal carotid artery (ICA) can result in disturbances of both cerebral and retinal microcirculations. We aimed to characterize parameters indicating cerebrovascular reactivity (CVR) and retinal microvascular density in patients with ICA stenosis, and assess if there is correlation between them. In this cross-sectional study the middle cerebral artery (MCA) blood flow velocity was measured by transcranial Doppler (TCD) and, simultaneously, continuous non-invasive arterial blood pressure measurement was performed on the radial artery by applanation tonometry. CVR was assessed based on the response to the common carotid artery compression (CCC) test. The transient hyperemic response ratio (THRR) and cerebral arterial resistance transient hyperemic response ratio (CAR-THRR) were calculated. Optical coherence tomography angiography (OCTA) was used to determine vessel density (VD) on the papilla whole image for all (VDP-WIall) and for small vessels (VDP-WIsmall). The same was done in the peripapillary region: all (VDPPall), and small (VDPPsmall) vessels. The VD of superficial (VDMspf) and deep (VDMdeep) macula was also determined. Significance was accepted when p<0.05. Twenty-four ICA stenotic patients were evaluated. Both CVR and retinal VD were characterized. There was a significant, negative correlation between CAR-THRR (median = -0.40) and VDPPsmall vessels (median = 52%), as well as between VDPPall vessels (median = 58%), and similar correlation between CAR-THRR and VDP-WIsmall (median = 49.5%) and between VDP-WIall (median = 55%). The significant correlation between impaired cerebrovascular reactivity and retinal vessel density in patients with ICA stenosis suggests a common mechanism of action. We propose that the combined use of these diagnostic tools (TCD and OCTA) helps to better identify patients with increased ischemic or other cerebrovascular risks.

Noninvasive continuous arterial pressure monitoring shortens atrial fibrillation ablation procedural duration

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Transcatheter atrial fibrillation (AF) ablation is in most centres commonly carried out with continuous invasive radial arterial blood pressure (BP) monitoring. Novel devices enable continuous non-invasive BP monitoring, with acceptable agreement and optimal safety profile when compared to standard of care invasive BP monitoring, leading to improved patient comfort in the electrophysiology lab. Purpose Aim of the study was to assess in terms of procedural efficiency continuous non-invasive BP monitoring during transcatheter atrial fibrillation ablation. Methods We prospectively enrolled 42 consecutive patients (age 61±9 years, 80% male) undergoing transcatheter AF ablation (60% paroxysmal, 40% persistent) at our centre undergoing AF ablation with continuous BP measurement using a non-invasive finger volume clamp device. We then compared them with an historical cohort of 42 consecutive patients undergoing AF ablation (62% paroxysmal, 38% persistent) with standard of care invasive BP monitoring with a radial cannula. We compared the two groups in terms of total procedural duration (in and out from the EP lab). Results Mean total procedural duration was 165,29±54,95 minutes in the non-invasive group and 196,55±46,67 minutes in the invasive group (P=0,006). Conclusion In patients undergoing AF ablation, non-invasive finger volume-clamp continuous BP monitoring allowed for a significant reduction of total procedural duration when compared to standard of care invasive BP monitoring. Larger studies are needed to confirm these results.

Clinical Validation of Wearable Piezoelectric Blood Pressure Sensor for Continuous Health Monitoring.

Wearable blood pressure sensors have recently attracted attention as healthcare devices for continuous non-invasive arterial pressure (CNAP) monitoring. However, the accuracy of wearable blood pressure (BP) monitoring devices has been controversial due to the low signal quality of sensors, the absence of an accurate transfer function to convert the sensor signals into BP values, and the lack of clinical validation regarding measurement precision. Here, we report a wearable piezoelectric blood pressure sensor (WPBPS), which achieved a high normalized sensitivity (0.062 kPa-1 ), fast response time (23ms) for CNAP monitoring. The transfer function of a linear regression model was designed, offering a simple solution to convert the flexible piezoelectric sensor signals into BP values. In order to verify the measurement accuracy of WPBPS, clinical trials were performed on 35 subjects aged from 20s to 80s after screening. The mean difference between the WPBPS and a commercial sphygmomanometer of 175 BP data pairs was -0.89 ± 6.19mmHg and -0.32 ± 5.28mmHg for systolic blood pressure (SBP) and diastolic blood pressure (DBP), respectively. By building a WPBPS-embedded wristwatch, we demonstrated the potentially promising use of a convenient, portable continuous BP monitoring system for cardiovascular disease diagnosis in this study. This article is protected by copyright. All rights reserved.

PO-01-208 A COMPUTATIONAL MODEL TO TRACK CHANGES IN LEFT VENTRICULAR END-DIASTOLIC PRESSURE DURING ATRIAL FIBRILLATION

Heart failure and Atrial Fibrillation (AF) commonly occur concomitantly, resulting in significant morbidity and mortality. Thus, monitoring of heart failure status is essential in directing medical therapy in these patients. Left ventricular (LV) filling pressures are one of the most important parameters in assessing worsened or acutely decompensated left heart failure, however current LV pressure monitoring strategies include invasive devices and catheterization. Our study aims to develop a computational model of heart failure in AF and demonstrate that beat-to-beat variations in RR intervals during AF can be exploited to predict changes in LV filling pressure. We used a modified Research CardioVascular SIMulator (RCVSIM) human cardiovascular model to simulate an intact circulatory system in patients with AF over 300 seconds. To simulate beat-by-beat variation of rhythm in AF, the length of each RR-interval was drawn randomly from a Mixed Gaussian Distribution. We modelled worsening HF by changing LV end-systolic compliance in the simulator, using compliances ranging from 1 to 3.5 mL/mmHg, with interval increases in compliance of 0.1 mL/mmHg. Stroke volumes, RR-intervals, and LV end-diastolic pressures are recorded for each simulation. This was repeated for mean heart rates from 60 to 110 beats per minute. Stroke volumes were found to have a strong linear correlation with the previous beat’s RR-interval for all mean heart rates tested (Spearman rho = 0.9-0.97). In Figure 1 below, we show the slope of the RR-interval versus stroke volume (SV/RR-interval) plotted against average LV end-diastolic pressure for all LV systolic compliances noted above and a mean heart rate of 84 beats per minute. A cubic function fit to this plot shows excellent goodness-of-fit with the simulated data with a coefficient of determination (R2) of 0.99. This relationship remained consistent for all mean heart rates tested, and all cubic fits had R2 greater than 0.98. Our study provides a highly accurate model for estimating LV end-diastolic pressures over a broad range of LV systolic heart failure in simulated AF patients using only stroke volume and RR-intervals. Further work using photoplethysmography or continuous non-invasive arterial pressure (CNAP) monitoring could potentially be used to obtain these measures non-invasively, thus leading to a non-invasive method for tracking heart failure in patients with AF.

Beat-to-beat finger photoplethysmography in atrial fibrillation patients undergoing electrical cardioversion

Atrial fibrillation (AF)-induced peripheral microcirculatory alterations have poorly been investigated. The present study aims to expand current knowledge through a beat-to-beat analysis of non-invasive finger photoplethysmography (PPG) in AF patients restoring sinus rhythm by electrical cardioversion (ECV). Continuous non-invasive arterial blood pressure and left middle finger PPG pulse oximetry waveform (POW) signals were continuously recorded before and after elective ECV of consecutive AF or atrial flutter (AFL) patients. The main metrics (mean, standard deviation, coefficient of variation), as well as a beat-to-beat analysis of the pulse pressure (PP) and POW beat-averaged value (aPOW), were computed to compare pre- and post-ECV phases. 53 patients (mean age 69 ± 8 years, 79% males) were enrolled; cardioversion was successful in restoring SR in 51 (96%) and signal post-processing was feasible in 46 (87%) patients. In front of a non-significant difference in mean PP (pre-ECV: 51.96 ± 13.25, post-ECV: 49.58 ± 10.41 mmHg; p = 0.45), mean aPOW significantly increased after SR restoration (pre-ECV: 0.39 ± 0.09, post-ECV: 0.44 ± 0.06 a.u.; p < 0.001). Moreover, at beat-to-beat analysis linear regression yielded significantly different slope (m) for the PP (RR) relationship compared to aPOW(RR) [PP(RR): 0.43 ± 0.18; aPOW(RR): 1.06 ± 0.17; p < 0.001]. Long (> 95th percentile) and short (< 5th percentile) RR intervals were significantly more irregular in the pre-ECV phases for both PP and aPOW; however, aPOW signal suffered more fluctuations compared to PP (p < 0.001 in both phases). Present findings suggest that AF-related hemodynamic alterations are more manifest at the peripheral (aPOW) rather than at the upstream macrocirculatory level (PP). Restoring sinus rhythm increases mean peripheral microvascular perfusion and decreases variability of the microvascular hemodynamic signals. Future dedicated studies are required to determine if AF-induced peripheral microvascular alterations might relate to long-term prognostic effects.

Feasibility and Accuracy of Noninvasive Continuous Arterial Pressure Monitoring during Transcatheter Atrial Fibrillation Ablation

Transcatheter atrial fibrillation (AF) ablation is still carried out with continuous invasive radial arterial blood pressure (IBP) monitoring in many centers. Continuous noninvasive blood pressure (CNBP) measurement using the volume-clamp method is a noninvasive alternative method used in ICU. No data on CNBP reliability are available in the electrophysiology lab during AF ablation, where rhythm variations are common. The objective of the present study was to compare continuous noninvasive arterial pressure measured with the ClearSight device (Edwards Lifesciences, Irvine, CA, USA) with invasive radial artery pressure used as the reference method during AF ablation. We prospectively enrolled 55 consecutive patients (age 62 ± 11 years, 80% male) undergoing transcatheter AF ablation (62% paroxysmal, 38% persistent) at our center. Standard of care IBP monitoring via a radial cannula and a contralateral noninvasive finger volume-clamp CNBP measurement device were positioned simultaneously in all patients for the entire procedure. Bland-Altman analysis was used to analyze the agreement between the two techniques. A total of 1219 paired measurements for systolic, diastolic, and mean arterial pressure were obtained in 55 subjects, with a mean (SD) of 22 (9) measurements per patient. The mean bias (SD) was -12.97 (13.89) mmHg for systolic pressure (level of agreement -14.24-40.20; correlation coefficient 0.84), -1.85 (8.52) mmHg for diastolic pressure (level of agreement -18.54-14.84; correlation coefficient 0.77) and 2.31 (8.75) mmHg for mean pressure (level of agreement -14.84-19.46; correlation coefficient 0.85). In patients undergoing AF ablation, CNBP monitoring with the ClearSight device showed acceptable agreement with IBP monitoring. Larger studies are needed to confirm the potential clinical implications of continuous noninvasive BP monitoring during AF ablation.

The consistency of invasive and non-invasive arterial blood pressure for the assessment of dynamic cerebral autoregulation in NICU patients.

Studies of the clinical application of dynamic cerebral autoregulation show considerable variations, and differences in blood pressure devices may be one of the reasons for this variation. Few studies have examined the consistency of invasive and non-invasive arterial blood pressure for evaluating cerebral autoregulation. We attempted to investigate the agreement between invasive and non-invasive blood pressure methods in the assessment of dynamic cerebral autoregulation with transfer function analysis. Continuous cerebral blood flow velocity and continuous invasive and non-invasive arterial blood pressure were simultaneously recorded for 15 min. Transfer function analysis was applied to derive the phase shift, gain and coherence function at all frequency bands from the first 5, 10, and 15 min of the 15-min recordings. The consistency was assessed with Bland-Altman analysis and intraclass correlation coefficient. The consistency of invasive and noninvasive blood pressure methods for the assessment of dynamic cerebral autoregulation was poor at 5 min, slightly improved at 10 min, and good at 15 min. The values of the phase shift at the low-frequency band measured by the non-invasive device were higher than those measured with invasive equipment. The coherence function values measured by the invasive technique were higher than the values derived from the non-invasive method. Both invasive and non-invasive arterial blood pressure methods have good agreement in evaluating dynamic cerebral autoregulation when the recording duration reaches 15 min. The phase shift values measured with non-invasive techniques are higher than those measured with invasive devices. We recommend selecting the most appropriate blood pressure device to measure cerebral autoregulation based on the disease, purpose, and design.

Can Hypotension Episodes that were not Identified in the Non-Invasive Blood Pressure be Detected during Cesarean Section? A Randomized Controlled Trial

Background:Neuraxial anesthesia is a commonly used technique for cesarean section (C/S) because of its simplicity, rapid onset of action, and the requirement of lower doses of anesthetic agents with the lack of uteroplacental transfer. However, this type of anesthesia often causes sudden onset of hypotension, and its pathogenesis is not yet clearly understood.Aims:To evaluate the efficacy and necessity of continuous noninvasive arterial pressure (CNAP) by comparing it with non-invasive blood pressure (NIBP) in order to understand whether it has advantages over oscillometric technique for detection of hypotensive episodes in healthy pregnant women who underwent C/S under neuraxial anesthesia.Study Design:A randomized controlled study.Methods:This prospective study evaluated healthy pregnant women at term who were scheduled for elective C/S under spinal anesthesia. Subjects were randomly assigned into two groups to receive either CNAP and NIBP, or only NIBP. A 30% decrease in systolic blood pressure from either baseline or the measured values in the first two minutes, or if the systolic blood pressure was less than 90 mmHg, is considered hypotension. Pre-, peri-, and postoperative specifications; newborn characteristics; and complications were recorded and compared.Results:A total of 106 individuals were enrolled in the study, with 53 parturients in each group. They were equally distributed in both groups (P > 0.05). The oscillometric method failed to detect hypotension in 8 out of 29 pregnant women who were noted to be hypotensive with CNAP. The number of hypotension events detected was higher, and the time to detection of the first episode of hypotension was shorter in the CNAP group (P > 0.05). A total of four newborns required intensive care unit treatment, one of whom needed mechanical ventilator support, all born to mothers in the CNAP group (P > 0.05).Conclusion:Continuous non-invasive arterial pressure in detecting hypotensive episodes does not provide an additional advantage to healthy pregnant women undergoing elective cesarean section.

Effects of experimental hypovolemia and pain on pre-ejection period and pulse transit time in healthy volunteers.

Trauma patients may suffer significant blood loss, and noninvasive methods to diagnose hypovolemia in these patients are needed. Physiologic effects of hypovolemia, aiming to maintain blood pressure, are largely mediated by increased sympathetic nervous activity. Trauma patients may however experience pain, which also increases sympathetic nervous activity, potentially confounding measures of hypovolemia. Elucidating the common and separate effects of the two stimuli on diagnostic methods is therefore important. Lower body negative pressure (LBNP) and cold pressor test (CPT) are experimental models of central hypovolemia and pain, respectively. In the present analysis, we explored the effects of LBNP and CPT on pre‐ejection period and pulse transit time, aiming to further elucidate the potential use of these variables in diagnosing hypovolemia in trauma patients. We exposed healthy volunteers to four experimental sequences with hypovolemia (LBNP 60 mmHg) or normovolemia (LBNP 0 mmHg) and pain (CPT) or no pain (sham) in a 2 × 2 fashion. We calculated pre‐ejection period and pulse transit time from ECG and ascending aortic blood velocity (suprasternal Doppler) and continuous noninvasive arterial pressure waveform (volume‐clamp method). Fourteen subjects were available for the current analyses. This experimental study found that pre‐ejection period increased with hypovolemia and remained unaltered with pain. Pulse transit time was reduced by pain and increased with hypovolemia. Thus, the direction of change in pulse transit time has the potential to distinguish hypovolemia and pain.

Non-invasive continuous arterial pressure monitoring during transcatheter atrial fibrillation ablation: a feasibility prospective study

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Transcatheter atrial fibrillation (AF) ablation is still carried out with continuous invasive radial arterial blood pressure (BP) monitoring in many centers. Continuous noninvasive blood pressure (CNBP) measurement using the volume-clamp method is a non invasive alternative method used in ICU. No data on CNBP reliability are available in the electrophysiology lab during AF ablation, where rhythm variations are common. Purpose The objective of the present study was to compare continuous noninvasive arterial pressure measured with the ClearSight device with invasive radial artery pressure, used as the reference method during AF ablation. Methods We prospectively enrolled 55 consecutive patients (age 62±11 years, 79% male) undergoing transcatheter AF ablation (62% paroxysmal, 38% persistent) at our center. Standard of care invasive BP monitoring via a radial cannula and a contro-lateral non-invasive finger volume-clamp continuous BP measurement device were positioned simultaneously in all patients for the entire procedure. Bland-Altman analysis was used to analyze agreement between the two techniques. Results A total of 1219 paired measurements for systolic, diastolic, and mean arterial pressure were obtained in 55 subjects, with a mean (SD) of 22 (9) measurements per patient. Mean bias (SD) was -12,97 (13,89) mmHg for systolic pressure (level of agreement -14,24–40,20; correlation coefficient 0,84), -1,85 (8,52) mmHg for diastolic pressure (level of agreement -18,54–14,84; correlation coefficient 0,77) and 2,31 (8,75) mmHg for mean pressure (level of agreement -14,84–19,46; correlation coefficient 0,85). Conclusion In patients undergoing AF ablation, non-invasive finger volume-clamp continuous BP monitoring with the ClearSight device showed acceptable agreement with standard of care invasive BP monitoring. Larger studies are needed to confirm potential clinical implications of a continuous non-invasive BP monitoring during AF ablation.

Fluid resuscitation with guidance of pulse pressure variability measured by continuous non-invasive arterial pressure monitor in postoperative hypovolemic patients: a prospective randomized controlled trial

Fluid resuscitation with guidance of pulse pressure variability measured by continuous non-invasive arterial pressure monitor in postoperative hypovolemic patients: a prospective randomized controlled trial

Measurement of Blood Pressure by Ultrasound-The Applicability of Devices, Algorithms and a View in Local Hemodynamics.

Objective: Due to ongoing technical progress, the ultrasonic measurement of blood pressure (BP) as an alternative to oscillometric measurement (NIBP) or the continuous non-invasive arterial pressure method (CNAP) moves further into focus. The US method offers several advantages over NIBP and CNAP, such as deep tissue penetration and the utilization of different arterial locations. Approach: Ten healthy subjects (six female, aged 30.9 ± 4.6 years) volunteered in our investigation. In the ultrasonic BP measurement, we differentiated between the directly measured (pulsatile diastolic and systolic vessel diameter) and indirectly calculated variables at three different artery locations on both arms, with two different ultrasound devices in the transversal and longitudinal directions of the transducer. Simultaneously, NIBP monitoring served as reference BP, while CNAP monitored the steady state condition of the arm under investigation. The Moens–Korteweg algorithm (MKE) and the algorithm of the working group of San Diego (SanD) were selected for the indirectly calculated ultrasonic BP data. Main results: With US, we were able to measure the BP at each selected arterial position. Due to the investigation setup, we found small but significant interactions of the main effects. Bland and Altman analysis revealed that US-BP measurement was similar to NIBP, with superior accuracy when compared to the established CNAP method. In addition, US-BP measurement showed that the measurement accuracy of both arms can be regarded as identical. In a detailed comparison of the selected arterial vascular sections, systematic discrepancies between the right and left arm could be observed. Conclusion: In our pilot study, we measured BP effectively and accurately by US using two different devices. Our findings suggest that ultrasonic BP measurement is an adequate alternative for live and continuous hemodynamic monitoring.

Comparison of restrictive fluid therapy with goal-directed fluid therapy for postoperative delirium in patients undergoing spine surgery: a randomized controlled trial

BackgroundPostoperative delirium (POD) is a common phenomenon after spinal surgery. Intraoperative fluid management may affect POD. The aim of this study was to compare the effects of restrictive fluid therapy (RF) with those of goal-directed fluid therapy (GDT) on POD.MethodsA total of 195 patients aged ≥ 50 years who underwent spinal surgery were randomly divided into two groups: the RF group and the GDT group. In group RF, a bolus of lactated Ringer’s solution was administered at a dose of 5 mL·kg-1 before the induction of anesthesia, followed by a dose of 5 mL·kg-1·h-1 until the end of surgery. For patients in the GDT group, in addition to the initial administration of lactated Ringer’s solution at 5 mL·kg-1, the subsequent fluid therapy was adjusted by using a continuous noninvasive arterial pressure (CNAP) monitoring system to maintain pulse pressure variation (PPV) ≤ 14%. The primary endpoint was the incidence of POD, assessed once daily with the Confusion Assessment Method-Chinese Reversion (CAM-CR) scale at 1–3 days postoperatively. The secondary endpoints were intraoperative fluid infusion volume, urine volume, mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), regional cerebral oxygen saturation (rSO2) value, lactic acid value, and visual analog scale (VAS) pain score at 1–3 days after surgery. Moreover, postoperative complications and the length of hospital stay were recorded.ResultsThe incidence of POD was lower in the GDT group than in the RF group (12.4% vs 4.1%; P = 0.035) in the first 3 days after spine surgery. Compared to group RF, group GDT exhibited a significantly increased volume of intraoperative lactated Ringer’s solution [1500 (interquartile range: 1128 to 1775) mL vs 1000 (interquartile range: 765 to 1300) mL, P < 0.001] and urine volume [398 (interquartile range: 288 to 600) mL vs 300 (interquartile range: 200 to 530) mL, P = 0.012]. Intraoperative MAP, CI and rSO2 values were higher in the GDT group than in the RF group (P < 0.05). Moreover, the length of hospital stay [17.0 (14 to 20) days versus 14.5 (13 to 17.0) days, P = 0.001] was shorter in the GDT group than in the RF group.ConclusionsGDT reduced the incidence of POD in middle- and old-aged patients undergoing spinal surgery possibly by stabilizing perioperative hemodynamic and improving the supply and demand of oxygen.Trial registrationChiCTR2000032603; Registered on May 3, 2020.

Hypotension Prediction Index with non-invasive continuous arterial pressure waveforms (ClearSight): clinical performance in Gynaecologic Oncologic Surgery

Intraoperative hypotension (IOH) is common during major surgery and is associated with a poor postoperative outcome. Hypotension Prediction Index (HPI) is an algorithm derived from machine learning that uses the arterial waveform to predict IOH. The aim of this study was to assess the diagnostic ability of HPI working with non-invasive ClearSight system in predicting impending hypotension in patients undergoing major gynaecologic oncologic surgery (GOS). In this retrospective analysis hemodynamic data were downloaded from an Edwards Lifesciences HemoSphere platform and analysed. Receiver operating characteristic curves were constructed to evaluate the performance of HPI working on the ClearSight pressure waveform in predicting hypotensive events, defined as mean arterial pressure < 65 mmHg for > 1 min. Sensitivity, specificity, positive predictive value and negative predictive value were computed at a cutpoint (the value which minimizes the difference between sensitivity and specificity). Thirty-one patients undergoing GOS were included in the analysis, 28 of which had complete data set. The HPI predicted hypotensive events with a sensitivity of 0.85 [95% confidence interval (CI) 0.73–0.94] and specificity of 0.85 (95% CI 0.74–0.95) 15 min before the event [area under the curve (AUC) 0.95 (95% CI 0.89–0.99)]; with a sensitivity of 0.82 (95% CI 0.71–0.92) and specificity of 0.83 (95% CI 0.71–0.93) 10 min before the event [AUC 0.9 (95% CI 0.83–0.97)]; and with a sensitivity of 0.86 (95% CI 0.78–0.93) and specificity 0.86 (95% CI 0.77–0.94) 5 min before the event [AUC 0.93 (95% CI 0.89–0.97)]. HPI provides accurate and continuous prediction of impending IOH before its occurrence in patients undergoing GOS in general anesthesia.

Noninvasive continuous arterial pressure monitoring during anesthesia induction in patients undergoing cardiac surgery.

Objective:In this study we compared noninvasive arterial pressure measurement using ClearSight™ vascular-unloading-technique (Edwards Lifesciences Corp, Irvine, CA) with invasive arterial pressure measurement during induction of anesthesia undergoing mayor cardiac surgery.Design:Prospective, monocentric.Setting:University hospital.Participants:54 patients undergoing mayor cardiac surgery.Interventions:During induction all patients were simultaneously monitored with invasive (reference method) and noninvasive arterial pressure measurement (test-method) over a mean time period of 27 minutes.Measurements and Main Results:We observed slightly lower systolic and mean arterial pressures noninvasive than invasive. For systolic arterial pressure the mean of the differences was -18,05 mmHg (p < 0,05, SD ±16,78 mmHg), the mean arterial pressure MAP -5,47 mmHg (p < 0,05, SD ±11,08 mmHg) and for diastolic pressure -1,09 mmHg (p < 0,05, SD±11,15 mmHg),. The mean of the differences in heartrate was 1,15 (p < 0,05, SD±6,9 mmHg). When considering all measured values of the invasively measured MAP and the ClearSight ™ -MAP at the same timestamp over the recording interval, an almost identical progress can be seen that indicates a sufficient mapping of the hemodynamic changes. The percentage error for mean arterial, systolic and diastolic pressure measured by ClearSight™ amounts to 25,95 %, 26,77 % and 34,16 %, respectively.Conclusions:We conclude that ClearSight ™ is a good option for hemodynamic monitoring during induction of anesthesia. Taking into account the limitations, non-invasive arterial blood pressure measurement offers sufficient security to safely initiate anesthesia, especially when MAP is of particular interest. The use of non-invasive arterial blood pressure measurement with ClearSight ™ during induction of anesthesia in patients scheduled for major cardiac surgery is reliable and easy to use.