Invasive Arterial Blood Pressure Research Articles

Association of Postarrest Hypotension Burden With Unfavorable Neurologic Outcome After Pediatric Cardiac Arrest.

Quantify hypotension burden using high-resolution continuous arterial blood pressure (ABP) data and determine its association with outcome after pediatric cardiac arrest. Retrospective observational study. Academic PICU. Children 18 years old or younger admitted with in-of-hospital or out-of-hospital cardiac arrest who had invasive ABP monitoring during postcardiac arrest care. None. High-resolution continuous ABP was analyzed up to 24 hours after the return of circulation (ROC). Hypotension burden was the time-normalized integral area between mean arterial pressure (MAP) and fifth percentile MAP for age. The primary outcome was unfavorable neurologic status (pediatric cerebral performance category ≥ 3 with change from baseline) at hospital discharge. Mann-Whitney U tests compared hypotension burden, duration, and magnitude between favorable and unfavorable patients. Multivariable logistic regression determined the association of unfavorable outcomes with hypotension burden, duration, and magnitude at various percentile thresholds from the 5th through 50th percentile for age. Of 140 patients (median age 53 [interquartile range 11-146] mo, 61% male); 63% had unfavorable outcomes. Monitoring duration was 21 (7-24) hours. Using a MAP threshold at the fifth percentile for age, the median hypotension burden was 0.01 (0-0.11) mm Hg-hours per hour, greater for patients with unfavorable compared with favorable outcomes (0 [0-0.02] vs. 0.02 [0-0.27] mm Hg-hr per hour, p < 0.001). Hypotension duration and magnitude were greater for unfavorable compared with favorable patients (0.03 [0-0.77] vs. 0.71 [0-5.01]%, p = 0.003; and 0.16 [0-1.99] vs. 2 [0-4.02] mm Hg, p = 0.001). On logistic regression, a 1-point increase in hypotension burden below the fifth percentile for age (equivalent to 1 mm Hg-hr of burden per hour of recording) was associated with increased odds of unfavorable outcome (adjusted odds ratio [aOR] 14.8; 95% CI, 1.1-200; p = 0.040). At MAP thresholds of 10th-50th percentiles for age, MAP burden below the threshold was greater in unfavorable compared with favorable patients in a dose-dependent manner. High-resolution continuous ABP data can be used to quantify hypotension burden after pediatric cardiac arrest. The burden, duration, and magnitude of hypotension are associated with unfavorable neurologic outcomes.

The influence of subclavian ansae stimulation on cardiac hemodynamics and electrophysiology in atrial fibrillation- exploring a novel target for neuromodulation in atrial fibrillation (SAS-AF study)

Abstract Background Sympathetic nervous system activation plays a significant role in arrhythmia development and maintenance.Neuromodulation techniques such as stellate ganglion block and sympathectomy, are limited by off-target side effects and complex targeting.The Subclavian Ansae (SA,a nerve cord encircling the subclavian artery) may be an intravascular site allowing specific targeting of the cardiac afferent sympathetic system.Preclinical studies have revealed increased sympathetic tone upon selective SA stimulation. Objective We sought to define for the first time in Humans the functional anatomy and physiology of Subclavian Ansae via a percutaneous approach. Methods A prior cadaveric study defined the anatomical course of the subclavian ansae, encircling the subclavian arteries and connecting the middle cervical ganglia to inferior cervical ganglia/stellate.Patients undergoing catheter ablation for paroxysmal atrial fibrillation(pAF) under general anesthesia were prospectively recruited for the study. Subclavian Ansae stimulation (SAS) was performed on the left and/or the right (L/SAS ± R/SAS) within the subclavian artery using the TactiCath Ablation Catheter introduced via a femoral arterial sheath. Stimulation parameters included up to 70 V output, 10 Hz frequency, and pulse width of 2-4ms for 20-30s. Test pulses ensured no cardiac capture during stimulation. Participants discontinued antiarrhythmic agents at least 4-5 half-lives prior to the procedure. Invasive arterial blood pressure(BP), heart rate (HR), and electrophysiological parameters were recorded in response to selective stimulation. An increase of ten percent or more in either arterial blood pressure(BP) or heart rate(HR) from the initial baseline measurements was deemed a positive response. Results 15 patients (62±11 years, 9 males, pAF duration 51±24 months) underwent the simulation protocol prior to their clinical AF ablation procedure. A positive hemodynamic response was observed in nine patients, and among them, arrhythmia was inducible in 3 patients (atrial fibrillation in 2 patients and repeated runs of atrial ectopy in 1 patient) in response to SAS. Mean sinus cycle length(CL) decreased(chronotropic) after stimulation,particularly with a significant change observed in response to R/SAS. Additionally,L/SAS led to a notable increase in mean systolic (SBP) and diastolic(DBP) blood pressure (inotropic). While the mean right atrial effective refractory period (ERP) did not significantly decrease after stimulation, there was a demonstrable difference in interatrial conduction time(dromotropy). Six patients, including the initial 3 subjected to low-energy stimulation (up to 12V), did not exhibit an adrenergic response. Conclusion This study represents the first successful application of selective SAS in humans. A heterogeneity in electrophysiological modulation by SAS exists, including laterality.The SA is a potential important target for targeted autonomic neuromodulation therapy

Hemodynamic effects of withholding vs. continuing angiotensin II receptor blockers on the day of prone positioning spinal surgery in elderly patients.

The hemodynamic effects of withholding vs. continuing angiotensin II receptor blockers (ARBs) before surgery in elderly patients undergoing spinal surgery in a prone position during anesthesia induction to skin incision are still unknown. In this prospective study, 80 patients undergoing spinal surgery in a prone position with general anesthesia, aged 60-79 years, American Society of Anesthesiologists (ASA) II or III, were enrolled. Patients who had ARBs only in their preoperative medication list were randomly divided into two groups at a 1:1 ratio: In Group A, ARBs were continued on the morning of surgery, while in Group B, they were withhold. Norepinephrine was infused to maintain the blood pressure at the baseline level of ±20% during anesthesia induction in all patients. The primary outcome was the consumption of norepinephrine in each group from anesthesia induction to skin incision. The secondary outcomes include changes in invasive arterial blood pressure and heart rate, the fluid infusion volumes, the amounts of anesthetic drugs, and the total time from induction to skin incision. There were no significant differences in the demographics, the fluid infusion volumes, the amounts of anesthetic drugs, the total time from induction to skin incision, and hemodynamics at different time points (p > 0.05), while significant differences were found in norepinephrine consumption between the two groups (p < 0.001). Compared with Group B, the consumption of norepinephrine increased significantly in Group A (93.3 ± 29.8 vs. 124.1 ± 38.7 μg, p = 0.000). In addition, the same trend was illustrated in the pumping rate of norepinephrine between Group B (0.04 ± 0.01 μg·kg-1·min-1) and Group A (0.06 ± 0.02 μg·kg-1·min-1) (p = 0.004). Our study conducted in elderly patients with hypotension undergoing prone spinal surgery demonstrated a greater pumping rate of norepinephrine during anesthesia induction in patients with ARBs continuing before surgery than those withholding, indicating that it was more difficult to maintain hemodynamic stability.Clinical Trial Registration: https://www.chictr.org.cn/showproj.html?proj=141081, ChiCTR2100053583.

Invasive arterial blood pressure delineator for cardiopulmonary resuscitation patients during pauses of chest compressions

Invasive arterial blood pressure (IBP) monitoring is important to assess patient’s cardiovascular competence and guide clinical treatment. Besides, international resuscitation guidelines in force suggest its use during Cardiopulmonary Resuscitation (CPR), but current automated algorithms for IBP variables computation were not designed for cardiac arrest patients. A lack of knowledge is detected in the automated processing of IBP signal during CPR.The aim of this study was to design algorithms for heartbeat detection and for IBP physiological variable computation during CPR, and compare to state-of-the-art (SoA) proposals. The dataset used consists of 81 out-of-hospital-cardiac-arrest (OHCA) patients and two additional public datasets with hemodynamically stable patients. A set of 377 IBP segments, total duration of 1127 min, were extracted from the OHCA dataset during the pauses of chest compressions. The method includes artifact removing from the in IBP using Stationary Wavelet Decomposition and heartbeat detection in the first difference signal. A multicomponent evaluation and two adaptive thresholds were applied to compute IBP physiological variables.Pulsatile segments with heartbeats were discriminated from pulseless segments with mean (standard deviation) sensitivity(Se)/specificity and positive (PPV)/negative predictive values of 98.8(6.9)/91.6(20.2)% and 97.4(9.7)/98.7(6.1)%, respectively. The heartbeat detection showed 96.1(8.3)% of Se, 96.1(7.6)% of PPV and 95.7(6.4)% of F1-score , with absolute errors of 0.55(2.91)/0.39(4.87)/0.78(6.08)mmHg in systolic, diastolic and pulse pressure values, respectively. The proposed algorithms outperformed SoA solutions with both OHCA and stable patients.

Automated cardiac arrest detection using a photoplethysmography wristband: algorithm development and validation in patients with induced circulatory arrest in the DETECT-1 study

Unwitnessed out-of-hospital cardiac arrest is associated with low survival chances because of the delayed activation of the emergency medical system in most cases. Automated cardiac arrest detection and alarming using biosensor technology would offer a potential solution to provide early help. We developed and validated an algorithm for automated circulatory arrest detection using wrist-derived photoplethysmography from patients with induced circulatory arrests. In this prospective multicentre study in three university medical centres in the Netherlands, adult patients (aged 18 years or older) in whom short-lasting circulatory arrest was induced as part of routine practice (transcatheter aortic valve implantation, defibrillation testing, or ventricular tachycardia induction) were eligible for inclusion. Exclusion criteria were a known bilateral significant subclavian artery stenosis or medical issues interfering with the wearing of the wristband. After providing informed consent, patients were equipped with a photoplethysmography wristband during the procedure. Invasive arterial blood pressure and electrocardiography were continuously monitored as the reference standard. Development of the photoplethysmography algorithm was based on three consecutive training cohorts. For each cohort, patients were consecutively enrolled. When a total of 50 patients with at least one event of circulatory arrest were enrolled, that cohort was closed. Validation was performed on the fourth set of included patients. The primary outcome was sensitivity for the detection of circulatory arrest. Of 306 patients enrolled between March 14, 2022, and April 21, 2023, 291 patients were included in the data analysis. In the development phase (n=205), the first training set yielded a sensitivity for circulatory arrest detection of 100% (95% CI 94-100) and four false positive alarms; the second training set yielded a sensitivity of 100% (94-100), with six false positive alarms; and the third training set yielded a sensitivity of 100% (94-100), with two false positive alarms. In the validation phase (n=86), the sensitivity for circulatory arrest detection was 98% (92-100) and 11 false positive circulatory arrest alarms. The positive predictive value was 90% (95% CI 82-94). The automated detection of induced circulatory arrests using wrist-derived photoplethysmography is feasible with good sensitivity and low false positives. These promising findings warrant further development of this wearable technology to enable automated cardiac arrest detection and alarming in a home setting. Dutch Heart Foundation (Hartstichting).

Sex differences in in-hospital management in patients with sepsis and septic shock: a prospective multicenter observational study

Sex differences in the in-hospital management of sepsis exist. Previous studies either included patients with sepsis that was defined using previous definitions of sepsis or evaluated the 3-h bundle therapy. Therefore, this study sought to assess sex differences in 1-h bundle therapy and in-hospital management among patients with sepsis and septic shock, defined according to the Sepsis-3 definitions. This observational study used data from Korean Shock Society (KoSS) registry, a prospective multicenter sepsis registry. Adult patients with sepsis between June 2018 and December 2021 were included in this study. The primary outcome was adherence to 1-h bundle therapy. Propensity score matching (PSM) and multivariable logistic regression analyses were performed. Among 3264 patients with sepsis, 3129 were analyzed. PSM yielded 2380 matched patients (1190 men and 1190 women). After PSM, 1-h bundle therapy was performed less frequently in women than in men (13.0% vs. 19.2%; p < 0.001). Among the bundle therapy components, broad-spectrum antibiotics were administered less frequently in women than in men (25.4% vs. 31.6%, p < 0.001), whereas adequate fluid resuscitation was performed more frequently in women than in men (96.8% vs. 95.0%, p = 0.029). In multivariable logistic regression analysis, 1-h bundle therapy was performed less frequently in women than in men [adjusted odds ratio (aOR) 1.559; 95% confidence interval (CI) 1.245–1.951; p < 0.001] after adjustment. Among the bundle therapy components, broad-spectrum antibiotics were administered less frequently to women than men (aOR 1.339, 95% CI 1.118–1.605; p = 0.002), whereas adequate fluid resuscitation was performed more frequently for women than for men (aOR 0.629, 95% CI 0.413–0.959; p = 0.031). Invasive arterial blood pressure monitoring was performed less frequently in women than in men. Resuscitation fluid, vasopressor, steroid, central-line insertion, ICU admission, length of stay in the emergency department, mechanical ventilator use, and renal replacement therapy use were comparable for both the sexes. Among patients with sepsis and septic shock, 1-h bundle therapy was performed less frequently in women than in men. Continuous efforts are required to increase adherence to the 1-h bundle therapy and to decrease sex differences in the in-hospital management of patients with sepsis and septic shock.

A comparison of invasive arterial blood pressure measurement with oscillometric non-invasive blood pressure measurement in patients with sepsis.

This study aimed to compare non-invasive oscillometric blood pressure (NIBP) measurement with invasive arterial blood pressure (IBP) measurement in patients with sepsis. We conducted a retrospective study to evaluate the agreement between IBP and NIBP using the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Paired blood pressure measurements of mean arterial pressure (MAP), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were compared using Bland-Altman analysis and paired Student's t test. We also focus on the effect of norepinephrine (NE) on the agreement between the two methods and the association between blood pressure and mortality during intensive care unit (ICU) stay. A total of 96,673 paired blood pressure measurements from 6060 unique patients were analyzed in the study. In Bland-Altman analysis, the bias (± SD, 95% limits of agreement) was 6.21mmHg (± 12.05mmHg, -17.41 to 29.83mmHg) for MAP, 0.39mmHg (± 19.25mmHg, -37.34 to 38.12mmHg) for SBP, and 0.80mmHg (± 12.92mmHg, -24.52 to 26.12mmHg) for DBP between the two techniques. Similarly, large limits of agreement were shown in different groups of NE doses. NE doses significantly affected the agreement between IBP and NIBP. SBP between the two methods gave an inconsistent assessment of patients' risk of ICU mortality. IBP and NIBP were not interchangeable in septic patients. Clinicians should be aware that non-invasive MAP was clinically and significantly underestimated invasive MAP.

Cardiac output estimation using ballistocardiography: a feasibility study in healthy subjects

There is no reliable automated non-invasive solution for monitoring circulation and guiding treatment in prehospital emergency medicine. Cardiac output (CO) monitoring might provide a solution, but CO monitors are not feasible/practical in the prehospital setting. Non-invasive ballistocardiography (BCG) measures heart contractility and tracks CO changes. This study analyzed the feasibility of estimating CO using morphological features extracted from BCG signals. In 20 healthy subjects ECG, carotid/abdominal BCG, and invasive arterial blood pressure based CO were recorded. BCG signals were adaptively processed to isolate the circulatory component from carotid (CCc) and abdominal (CCa) BCG. Then, 66 features were computed on a beat-to-beat basis to characterize amplitude/duration/area/length of the fluctuation in CCc and CCa. Subjects’ data were split into development set (75%) to select the best feature subset with which to build a machine learning model to estimate CO and validation set (25%) to evaluate model’s performance. The model showed a mean absolute error, percentage error and 95% limits of agreement of 0.83 L/min, 30.2% and − 2.18–1.89 L/min respectively in the validation set. BCG showed potential to reliably estimate/track CO. This method is a promising first step towards an automated, non-invasive and reliable CO estimator that may be tested in prehospital emergencies.

Accuracy of Noninvasive Blood Pressure Monitoring in Critically Ill Adults.

Background: Blood pressure (BP) is routinely invasively monitored by an arterial catheter in the intensive care unit (ICU). However, the available data comparing the accuracy of noninvasive methods to arterial catheters for measuring BP in the ICU are limited by small numbers and diverse methodologies. Purpose: To determine agreement between invasive arterial blood pressure monitoring (IABP) and noninvasive blood pressure (NIBP) in critically ill patients. Methods: This was a single center, observational study of critical ill adults in a tertiary care facility evaluating agreement (≤10% difference) between simultaneously measured IABP and NIBP. We measured clinical features at time of BP measurement inclusive of patient demographics, laboratory data, severity of illness, specific interventions (mechanical ventilation and dialysis), and vasopressor dose to identify particular clinical scenarios in which measurement agreement is more or less likely. Results: Of the 1852 critically ill adults with simultaneous IABP and NIBP readings, there was a median difference of 6 mm Hg in mean arterial pressure (MAP), interquartile range (1-12), P < .01. A logistic regression analysis identified 5 independent predictors of measurement discrepancy: increasing doses of norepinephrine (adjusted odds ratio [aOR] 1.10 [95% confidence interval, CI 1.08-1.12] P = .03 for every change in 5 µg/min), lower MAP value (aOR 0.98 [0.98-0.99] P < .01 for every change in 1 mm Hg), higher body mass index (aOR 1.04 [1.01-1.09] P = .01 for an increase in 1), increased patient age (aOR 1.31 [1.30-1.37] P < .01 for every 10 years), and radial arterial line location (aOR 1.74 [1.16-2.47] P = .04). Conclusions: There was broad agreement between IABP and NIBP in critically ill patients over a range of BPs and severity of illness. Several variables are associated with measurement discrepancy; however, their predictive capacity is modest. This may guide future study into which patients may specifically benefit from an arterial catheter.

An end-to-end deep learning framework for accurate estimation of intracranial pressure waveform characteristics

It is clinically significant if intracranial pressure (ICP) waveform could be reliably reconstructed from simple physiological measurements that are commonly used in clinical practice. Some attempts have been made with the focus on estimating intermittent mean ICP (MICP) values, but no investigation has been performed to reconstruct beat-by-beat ICP waveforms from arterial blood pressure (ABP) waveforms. This study aimed to overcome this challenge. A large dataset of 28511 segments (10.8 s for each segment; 540 samples) of simultaneously measured invasive ABP and ICP signals was used to develop and cross-evaluate a Wave-U-Net based deep learning model for reconstructing ICP waveform from ABP signals. From the reconstructed beat-by-beat ICP waveform, systolic ICP, diastolic ICP, and MICP were derived for each cardiac cycle and compared with reference ICPs. After comparing all the sampling points of each segment, the results showed that the reconstructed ICP waveforms were statistically correlated to the reference ICP waveforms, with the average Pearson's correlation coefficient (r) of 0.822 across all the segments. There was no significant difference between the estimated and reference ICP values, with the mean absolute error (MAE) of systolic ICP, diastolic ICP and MICP of 0.75 ± 0.29, 0.48 ± 0.22 and 0.42 ± 0.18 mmHg, respectively, meeting the clinical standards of ICP monitoring for the management of traumatic brain injury. Our proposed method confirmed the hypothesis for the first time that ABP waveform can be used for reliable reconstruction of ICP waveform, enabling continuous monitoring of ICP waveform, and providing the hope possibility to replace the gold standard invasive technique.

Micro- and macrocirculatory effects of norepinephrine on anaesthesia-induced hypotension: a prospective preliminary study

BackgroundIntraoperative arterial hypotension (IOH) leads to increased postoperative morbidity. Norepinephrine is often use to treat IOH. The question regarding the mode of administration in either a bolus or continuous infusion remains unanswered. The aim of the present study was to describe and compare the effects on macrocirculation and microcirculation of a bolus and a continuous infusion of norepinephrine to treat IOH.MethodsWe conducted a prospective observational study with adult patients who underwent neurosurgery. Patients with invasive arterial blood pressure and cardiac output (CO) monitoring were screened for inclusion. All patients underwent microcirculation monitoring by video-capillaroscopy, laser doppler, near-infrared spectroscopy technology, and tissular CO2. In case of IOH, the patient could receive either a bolus of 10 µg or a continuous infusion of 200 µg/h of norepinephrine. Time analysis for comparison between bolus and continuous infusion were at peak of MAP. The primary outcome was MFI by videocapillaroscopy.ResultsThirty-five patients were included, with 41 boluses and 33 continuous infusion.Bolus and continuous infusion induced an maximal increase in mean arterial pressure of +30[20-45] and +23[12-34] %, respectively (P=0,07). For macrocirculatory parameters, continuous infusion was associated with a smaller decrease in CO and stroke volume (p<0.05).For microcirculatory parameters, microvascular flow index (-0,1 vs. + 0,3, p=0,03), perfusion index (-12 vs. +12%, p=0,008), total vessel density (-0,2 vs. +2,3 mm2/mm2, p=0,002), showed significant opposite variations with bolus and continuous infusion, respectively.ConclusionsThese results on macro and microcirculation enlighten the potential benefits of a continuous infusion of norepinephrine rather than a bolus to treat anaesthesia-induced hypotension.Trial registration(NOR-PHARM: 1-17-42 Clinical Trials: NCT03454204), 05/03/2018

The effect of intraoperative cerebral oxygen desaturations on postoperative cerebral oxygen metabolism in neonates and infants a pilot study.

Cerebral oxygen desaturation during pediatric surgery has been associated with adverse perioperative outcomes. The aim of this pilot study was to analyze the frequency and severity of intraoperative cerebral oxygen desaturations and their impact on postoperative cerebral oxygen metabolism in neonates and infants undergoing pediatric surgery. In a prospective pilot study, intra- and postoperative regional cerebral oxygen saturation and blood flow were measured noninvasively using a device combining laser Doppler flowmetry and white-light-spectrometry. Thirty-seven consecutive neonates and infants undergoing noncardiac surgery under general anesthesia for more than 30 min and necessity for invasive arterial blood pressure monitoring were included. Patients with pre-known congenital structural heart disease or cerebral disease were excluded. Continuously brain monitor recording was started in sedated patients before induction of anesthesia (preoperative baseline) and was completed 1 h postoperatively in the PICU in sedated, intubated, and mechanically ventilated states at the PICU (postoperative state). Baseline and postoperative state for cerebral fractional tissue oxygen extraction and approximated cerebral metabolic rate of oxygen were calculated. Seventeen (46%) of the 37 studied neonates and infants suffered from intraoperative periods of regional cerebral oxygen desaturation below 20% of the baseline (event group). Severity of cerebral desaturations was median 4.0%min/h [range 0.1-58.7; interquartile range [IQR] 0.99-21.29]. In the event group, the duration of surgery was significantly longer (median 135 min [range 11-260; IQR 113.5-167.0] vs median 46.5 min [range 11-180; IQR 30.5-159.3]; difference of -62.94; 95% confidence interval [CI] -105.17 to -20.71; p = .021). In the event group, cerebral fractional tissue oxygen extraction (median 0.41 [range 0.20-0.55; IQR 0.26-0.44] vs. median 0.27 [range 0.11-0.41; IQR 0.20-0.31]; difference of -0.11; 95% CI -0.17 to -0.05; p = .001) and approximated cerebral metabolic rate of oxygen (median 6.15 arbitrary unit [range 2.69-12.07; IQR 5.12-7.21] vs. median 4.14 arbitrary unit [range 1.78-7.86; IQR 3.82-6.31]; difference of -1.76; 95% CI -3.03 to -0.49; p = .009) were significantly higher and the cerebral regional oxygen saturation (median 58.99% [range 44.87-79.1; IQR 54.26-72.61] vs median 70.94% [range 57.9-86.13; IQR 67.07-76.59]; difference of 10.01; 95% CI 4.13-15.90; p = .002) significantly lower after surgery compared to the nonevent group. The increase of approximated cerebral metabolic rate of oxygen could indicate an elevated oxidative energy metabolism in the "stressed" brain, due to repair processes. The increased cerebral fractional tissue oxygen extraction fits with the decreased NIRS cerebral oxygenation. Our data suggest that an increase in cerebral oxygen metabolism was the cause. Cerebral oxygen desaturation during major surgery in neonates and infants is associated with early postoperative increased cerebral oxygen extraction and possibly increased cerebral oxygen metabolism.

Left Ventricular Ejection Time Estimation from Blood Pressure and Photoplethysmography Signals Based on Tidal Wave

Left ventricular ejection time (LVET) is an important parameter for assessing cardiovascular disorders. In a medical office, it is typically measured using the Tissue Doppler Imaging technique, but new wearable devices have led to a growing interest in integrating this parameter into them, increasing accessibility to personalized healthcare for users and patients. In the cardiovascular domain, photoplethysmography (PPG) is a promising technology that shares two distinctive features with invasive arterial blood pressure (ABP) tracing: the tidal wave (TDW) and the dicrotic wave (DCW). In the early years of cardiovascular research, the duration of the dicrotic point was initially linked to the ending phase of left ventricular ejection. Subsequent studies reported deviations from the initial association, suggesting that the ejection period is related to the tidal wave feature. In this current study, we measured left ventricular ejection time in both ABP and PPG waveforms, considering recent research results. A total of 27,000 cardiac cycles were analyzed for both afore-mentioned signals. The reference value for ejection time was computed based on the T-wave segment duration from the electrocardiogram waveform. In lower blood pressure, which is associated with decreased heart contractility, the results indicated an underestimation of −29 ± 19 ms in ABP and an overestimation of 18 ± 31 ms in PPG. On the other side of the spectrum, during increased contractility, the minimum errors were −3 ± 18 ms and 4 ± 33 ms, respectively. Since the tidal wave feature is strongly affected by arterial tree compliance, the population evaluation results indicate a Pearson’s correlation factor of 0.58 in the ABP case, and 0.53 in PPG. These findings highlight the need for advanced compensation techniques, in particular for PPG assessment, to achieve clinical-grade accuracy.

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.

Lowest peak central venous pressure correlates with highest invasive arterial blood pressure as a method for optimising AV delay in post-surgical temporary pacing

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): British Heart Foundation. Background Atrioventricular (AV) delay optimisation has been performed using a variety of methods, including doppler outflow and alternating blood pressure algorithms. Patients after cardiac surgery are usually invasively monitored with arterial and central venous pressure (CVP) lines. Purpose We aimed to see if the CVP line could be used to optimise AV delays in temporary pacing for situations where the arterial line is absent or non-functional. Methods 11 patients in sinus rhythm but with temporary pacemakers after cardiac surgery were studied. Each patient underwent alternating optimisation algorithms where they were subjected to 8 transitions between a reference AV delay of 120ms and a tested AV delay ranging from 40ms to 280 ms. Testing was terminated after the AV delay occurred when native conduction occurred i.e after they began AAI pacing. All patients were paced at 80 bpm. Arterial blood pressure (ABP) and CVP were recorded from radial arterial lines and central venous lines in the internal jugular vein during the transitions. The optimal point was defined as the AV delay generating the maximum systolic blood pressure. The CVP was measured in 3 ways: peak pressure, mean pressure, and area under the curve. Central venous pressure tracings were corrected for respiration using a "fit-a-curve" function. All analysis was performed in Python. Results Individual pressure readings. There was a negative correlation between individual ABP and Peak CVP pressure readings (R= -0.539, p=0&amp;lt;0.001). A representative example for a single patient is shown in Figure 1 and for all data in Figure 2. A similar relationship, albeit less strong, was seen between ABP and Mean CVP (R= -0.281, p=0.046). There was no significant relationship between ABP and CVP AUC (R = -0.281, p=0.130). Optimum pressure settings: There was a strong correlation between the optimum AV delay as defined by the highest ABP and the optimum AVD as defined by the lowest peak CVP (R = 0.672, p=0.03). There was no significant relationship between the optimum AVD delay as defined by peak ABP and the optimum AVD defined by either mean CVP nor CVP AUC (R=0.269, p=0.452 for both). Conclusions There is an inverse relationship between individual measurements of arterial blood pressure and both peak and mean central venous pressure. The optimal AVD as defined by the highest ABP correlates with the optimal AVD as defined by the lowest peak CVP measurement. However, this method does require correction for respiratory artefact.

Noninvasive finger plethysmography for continuous blood pressure monitoring in patients with left ventricular assist device.

Accurate blood pressure (BP) measurement remains challenging in patients with HeartMate 3™ left ventricular assist devices (HM3 LVADs). The Finapres® NOVA is a promising non-invasive continuous BP monitor that uses the volume clamp method via a finger cuff, so here we aimed to validate the instrument in HM3 patients. In a single-center cohort, BP was monitored in 15 patients within 72 h following HM3 implantation. A radial artery catheter quantified arterial blood pressure (ABP), while the NOVA measured finger arterial pressure (fiAP) and reconstructed brachial artery pressure (reBAP). Waveforms were recorded for 10 min, and mean values were calculated in 15-s intervals. fiAP and ABP were moderately correlated during both the first (ICC 0.61, p = 0.04) and final measurements (ICC 0.66, p = 0.03). reBAP and ABP were strongly correlated during both the first (ICC 0.81, p = 0.002) and final measurements (ICC 0.83, p = 0.001). Both NOVA-derived values may underestimate low BP values while overestimating relatively high BP values. The reBAP was within 5 mm Hg of the ABP in 40% of patients (and within 10 mm Hg in 67%). This pilot represents the first evidence in support of the Finapres® NOVA for non-invasive BP measurement in select patients with HM3 LVADs. The instrument may provide useful data during BP medication adjustments or pump titration, but despite the correlation between the non-invasive reBAP and invasive ABP, individual-level inaccuracy may be clinically meaningful. Further investigation is needed to clarify these limitations and optimize accuracy before widespread adoption in this unique patient population.

Wrist ballistocardiography and invasively recorded blood pressure in healthy volunteers during reclining bike exercise.

Objective: Ballistocardiogram (BCG) features are of interest in wearable cardiovascular monitoring of cardiac performance. We assess feasibility of wrist acceleration BCG during exercise for estimating pulse transit time (PTT), enabling broader cardiovascular response studies during acute exercise and improved monitoring in individuals at risk for cardiovascular disease (CVD). We also examine the relationship between PTT, blood pressure (BP), and stroke volume (SV) during exercise and posture interventions. Methods: 25 participants underwent a bike exercise protocol with four incremental workloads (0W, 50W, 100W, and 150W) in supine and semirecumbent postures. BCG, invasive radial artery BP, tonometry, photoplethysmography (PPG) and echocardiography were recorded. Ensemble averages of BCG signals determined aortic valve opening (AVO) timings, combined with peripheral pulse wave arrival times to calculate PTT. We tested for significance using Wilcoxon signed-rank test. Results: BCG was successfully recorded at the wrist during exercise. PTT exhibited a moderate negative correlation with systolic BP (ρSup = -0.65, ρSR = -0.57, ρAll = -0.54). PTT differences between supine and semirecumbent conditions were significant at 0W and 50W (p < 0.001), less at 100W (p = 0.0135) and 150W (p = 0.031). SBP and DBP were lower in semirecumbent posture (p < 0.01), while HR was slightly higher. Echocardiography confirmed association of BCG features with AVO and indicated a positive relationship between BCG amplitude and SV (ρ = 0.74). Significance: Wrist BCG may allow convenient PTT and possibly SV tracking during exercise, enabling studies of cardiovascular response to acute exercise and convenient monitoring of cardiovascular performance.

Investigation of effective invasive blood pressure control methods to prevent acute exacerbation of acute aortic dissection.

Acute aortic dissection is associated with high mortality and increased risk of complications. Acute exacerbations have a relatively high frequency; however, the contributing factors are unclear. Blood pressure (BP) and heart rate control are important factors, but the ideal BP control strategy to prevent acute exacerbations under invasive arterial pressure monitoring remains unclear. Therefore, in this study, we aimed to determine the relationship between invasive arterial BP and the effects of acute exacerbation of aortic dissection. This single-centre, retrospective, case-control study included 104 patients with a partial diagnosis of acute aortic dissection (Stanford type A or B) who were treated conservatively between September 2013 and September 2022. The patients were divided into exacerbation (acute exacerbation; n = 26) and stable (no acute deterioration) groups. The SBP trend (122.5 ± 13.1 vs. 116.6 ± 10.6 mmHg, respectively; P = 0.024) and mean BP trend (77.8 ± 5.8 vs. 74.4 ± 7.5 mmHg, respectively; P = 0.038) significantly differed between the two groups. The time to target BP was significantly longer in the exacerbation group ( P = 0.036). The exacerbation group did not achieve a mean SBP < 120 mmHg. Moreover, the importance of early BP reduction was demonstrated in the present study.

Photoplethysmography waveform analysis for classification of vascular tone and arterial blood pressure: Study based on neural networks

To test whether a Shallow Neural Network (S-NN) can detect and classify vascular tone dependent changes in arterial blood pressure (ABP) by advanced photopletysmographic (PPG) waveform analysis. PPG and invasive ABP signals were recorded in 26 patients undergoing scheduled general surgery. We studied the occurrence of episodes of hypertension (systolic arterial pressure (SAP) >140 mmHg), normotension and hypotension (SAP < 90 mmHg). Vascular tone according to PPG was classified in two ways: 1) By visual inspection of changes in PPG waveform amplitude and dichrotic notch position; where Classes I-II represent vasoconstriction (notch placed >50% of PPG amplitude in small amplitude waves), Class III normal vascular tone (notch placed between 20-50% of PPG amplitude in normal waves) and Classes IV-V-VI vasodilation (notch <20% of PPG amplitude in large waves). 2) By an automated analysis, using S-NN trained and validated system that combines seven PPG derived parameters. The visual assessment was precise in detecting hypotension (sensitivity 91%, specificity 86% and accuracy 88%) and hypertension (sensitivity 93%, specificity 88% and accuracy 90%). Normotension presented as a visual Class III (III-III) (median and 1st-3rd quartiles), hypotension as a Class V (IV-VI) and hypertension as a Class II (I-III); all p < .0001. The automated S-NN performed well in classifying ABP conditions. The percentage of data with correct classification by S-ANN was 83% for normotension, 94% for hypotension, and 90% for hypertension. Changes in ABP were correctly classified automatically by S-NN analysis of the PPG waveform contour.

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.