Arterial Waveform Research Articles

A Deep Learning Framework for the Detection of Abnormality in Cerebral Blood Flow Velocity Using Transcranial Doppler Ultrasound.

Transcranial doppler (TCD) ultrasound is a non-invasive imaging technique that can be used for continuous monitoring of blood flow in the brain through the major cerebral arteries by calculating the cerebral blood flow velocity (CBFV). Since the brain requires a consistent supply of blood to function properly and meet its metabolic demand, a change in CBVF can be an indication of neurological diseases. Depending on the severity of the disease, the symptoms may appear immediately or may appear weeks later. For the early detection of neurological diseases, a classification model is proposed in this study, with the ability to distinguish healthy subjects from critically ill subjects. The TCD ultrasound database used in this study contains signals from the middle cerebral artery (MCA) of 6 healthy subjects and 12 subjects with known neurocritical diseases. The classification model works based on the maximal blood flow velocity waveforms extracted from the TCD ultrasound. Since the signal quality of the recorded TCD ultrasound is highly dependent on the operator's skillset, a noisy and corrupted signal can exist and can add biases to the classifier. Therefore, a deep learning classifier, trained on a curated and clean biomedical signal can reliably detect neurological diseases. For signal classification, this study proposes a Self-organized Operational Neural Network (Self-ONN)-based deep learning model Self-ResAttentioNet18, which achieves classification accuracy of 96.05% with precision, recall, f1 score, and specificity of 96.06%, 96.05%, 96.06%, and 96.09%, respectively. With an area under the ROC curve of 0.99, the model proves its feasibility to confidently classify middle cerebral artery (MCA) waveforms in near real-time.

Particle Filter Based Framework for the Prognosis of Atherosclerosis via Lumped Cardiovascular Modeling

Atherosclerosis refers to the plaque deposition in the arteries that can eventually lead to any of the three cardiovascular diseases, namely, heart attack, stroke, or peripheral vascular disease, depending upon the site of the blockage in the human arterial network. This work attempts to prognose this pathological condition via lumped cardiovascular modeling while utilizing the radial artery blood pressure measurements. To achieve this, the cardiovascular system has been modeled as a third order non-linear system with explicit emphasis on the systemic circulation. The parameters of the model are estimated using non-linear least squares estimation technique by minimizing the error between the measured and the estimated arterial pressure waveforms. The arterial pressure is found to be sensitive to three of the model parameters, namely, arterial compliance, systemic vascular resistance, and the peak cardiac muscle elastance. Based on the analysis, a growth model of systolic blood pressure is developed as a function of the arterial blockage. A particle filter based mathematical framework is then utilized to predict the time it would take to reach the stage of critical arterial blockage that may cause heart attacks.

A HEAD-TO-HEAD COMPARISON OF PULSE TRANSIT TIME USING SECOND-DERIVATIVE AND INTERSECTING TANGENTS METHODS

Objective: Determination of aortic stiffness as measured by carotid-femoral pulse wave velocity (CFPWV) is based on pulse transit time (PTT). PTT is determined by identification of the foot of the pressure wave using either the peak of the second-derivative or the intersecting tangents algorithm. The aim of this study was to examine if there are any differences when these algorithms are performed on the same arterial pressure waveforms. Design and method: Carotid and femoral arterial pressure waveforms were simultaneously recorded using the piezoelectric sensors of the Complior Analyse system. Waveforms were extracted and imported into In-house software (MATLAB; MathWorks, Natick, Massachusetts, USA) to calculate the PTT only on valid pressure waveforms without artifacts that are due to movements. Results: In 105 human subjects (59 ± 18 years; 64% men) including a mix of 59% hypertensive, 34% with chronic kidney disease, 16% diabetic and 13% with cardiovascular disease, the average brachial blood pressure was 125 ± 18/73 ± 10 mmHg. A total of 6 203 pairs of simultaneous carotid and femoral arterial pressure waveforms were analysed. The PTT using the second-derivative algorithm was 68.4 ± 18.6 ms (CFPWV: 9.48 ± 3.18 m/s), similar to PTT using the intersecting tangents method that was 68.6 ± 18.8 (CFPWV: 9.45 ± 3.12). This difference while statistically significant given the high number of observation points (P < 0.001), is not considered to be clinically significant. Conclusions: Based on our findings, both algorithms perform similarly and can be used interchangeably when high quality acquisition are used. However, device-based algorithms may perform differently given variabilities in quality assessment criteria.

HEMODYNAMICS STRESS TEST USING FINGER-TO-TOE PULSE WAVE VELOCITY IN SUPINE AND SITTING POSITION IN END-STAGE KIDNEY DISEASE

Objective: Aortic pulse wave velocity (PWV), a measure of arterial stiffness can either be measured by the ratio of distance to pulse transit time or, estimated based on the pulse wave profile (ePWV). Aortic PWV measurements are performed in the supine position as there is no added hydrostatic pressure along the arterial path, and the recording of the arterial pressure waveform of the femoral arterial is easier to perform. However, finger-to-toe PWV (ftPWV), a surrogate for aortic PWV, can easily be performed in other positions, such as the sitting position, giving the opportunity to examine arterial wall properties in a dynamic manner. The aim of the study was to observe the impact of the position (supine vs sitting) on the ePWV and on the measured ftPWV in patients with end-stage kidney disease. Design and method: In a cross-sectional study involving adult hemodialysis patients, we performed vascular assessments in the supine and the sitting position within the first 2 hours of their hemodialysis session. The ePWV was obtained using the Mobil-O-Graph and ftPWV was obtained using the pOpmètre®. Three measures were taken with each device. Generalized estimated equations were then used to calculate the average of ePWV and ftPWV with respect to each position. Results: In 46 patients (17 females), the average age was 71±12 years and the blood pressure was 136±24 /77±15 mmHg. The ePWV was 10.8 m/s (IC95% :10.1-11.4 m/s) in the supine position and 10.7 m/s (IC95%: 10.0-11.3 m/s) in the sitting position. However, the ftPWV was 12.1 m/s (IC95%: 9.6-14.7 m/s) in the supine position but it increased to 22.0 m/s (IC95%: 15.0-29.0 m/s) in the sitting position. This increase of 9.8 m/s was highly significant (P = 0.006) even though the brachial blood pressure and the heart rate had barely changed. Conclusions: This study shows that finger-to-toe PWV increases in the sitting position, offering us the opportunity to explore this postural changes in PWV as a possible vascular stress test.

P68: Atypical Presentation of Pump Thrombosis in HVAD: Usefulness of HVAD Waveforms in Diagnosing Pump Thrombosis

Background: Pump thrombosis is a life-threatening complication from left ventricular assist device (LVAD). Early recognition and diagnosis is essential to prevent adverse outcomes. This case study illustrates an atypical presentation of pump thrombosis. Method: A 62-year-old male with ischemic cardiomyopathy s/p HVAD implant suffered an intercranial hemorrhage in the setting of MDR pseudomonas bacteremia. Patient’s anticoagulation was reversed and an emergent craniotomy was successfully performed. Hemolysis markers were unremarkable (LDH < 300 U/L, plasma free hemoglobin <10mg/dL). On POD 4, an intermittent loss of pulse variability was noted on the HVAD waveform and on the radial arterial line waveform (Figure 1). This loss lasted 10 seconds, self-resolved and reoccurred every few minutes. It was not associated with hemolysis, decrease in powers, arrythmia, hypovolemia or postural changes. The patient was hemodynamically stable and discharged to an acute rehabilitation center without resolution of this intermittent loss of pvar. Result The patient subsequently underwent an orthotopic heart transplant. Upon inspection of the explanted heart, a large mobile clot was noted at the inflow cannula (Picture 1). The clot partial intermittent obstruction of the inflow cannula likely caused the intermittent loss of pulsatility. Conclusion: Inflow pump thrombosis does not always present with classic hallmark sign such as loss of power and flow, hemolysis markers elevation and worsening heart failure and can be difficult to diagnose. This case illustrates the usefulness of HVAD waveform assessment to identify early signs of pump thrombosis.Figure 1. Progressive loss of pulsatilityFigure 2. Progressive loss of pulsatilityFigure 3. A view of the left ventricle with inflow cannula with mobile clot

ARTERY ELASTICITY INDICES AND TESTOSTERONE- LONGITUDINAL STUDY IN VARA- SKÖVDE COHORT

Objective: To determine the associations between testosterone, sex hormone-binding globulin (SHBG) and arterial elasticity in men in a longitudinal observational study. Design and method: 2816 randomly selected individuals were examined (Men = 1400) between 2002 and 2005. After excluding participants with known hypertension and without data for arterial elasticity and testosterone, we include 1202 men in cross-sectional analyses. After a mean follow-up of 9.7 ± 1.4 years, a representative sample of 1327 original participants was re-examined. In the longitudinal analysis, 473 men were included. Body height, weight, heart rate and blood pressure were measured. Total testosterone (TT) and SHBG were analyzed using RIA. Bioavailable testosterone (BioT) is calculated by the Vermeulen coefficient. Arterial elasticity was measured based on pulse contour analysis of arterial waveform using the HDI/Pulse WaveTM CR2000 and C1 and C2 were obtained. Linear regression models were used to investigate these associations in three models: in model 1 adjusting for age, in model 2 we added heart rate, systolic blood pressure and in model 3 we added BMI. Multivariable general linear models were used to investigate the differences in C1 and C2 based on testosterone deficiency. Results: Mean age at baseline was 46.2±10.9 years. In cross-sectional analysis, an increase in TT and BioT was associated with an increase of C1 (beta = 0.08, CI: 0.02-0,14, p = 0.01 resp beta = 0.14, CI: 0.001-0.272, p = 0.05) in model 1, but not in the other models. In model 1 participants with testosterone deficiency had significantly lower C1 (C1 in TD: 17.6±5, C1 in the normal level of TT: 18.2±5, delta C1: 0.6, CI: 0.06- 1.1; p = 0.05), but not in the other models. Other associations between TT, BioT, SHBG, TD and C1 respective C2 were not significant in the models. Conclusions: We found weak associations between artery elasticity indices and testosterone levels. Surprisingly these associations were not significant after adjustments for pulse and blood pressure, even though the sample was large enough to reveal clinically significant associations.

(359) Validation of Peripheral Endothelial Assessment and Central Arterial Tonometry as Tools in Arteriogenic Erectile Dysfunction and Can These Tools Aid in Better Selection of Patients for LI-ESWT Treatment Improving Success Rates?

Abstract Introduction An important mechanism of ED is vascular endothelial function injury or disorder and low-intensity extracorporeal shock wave therapy (LI-ESWT) can stimulate and promote vascular regeneration, especially in failed PDE5i. The present selection criteria used for EDSWT are subjective in the form of IIEF, EHS or SEP with no objective definition of the extent of vascular involvement. There is a need to comprehensively evaluate ED including the extent of local and systemic involvement. Objective To develop objective parameters of validated assessment of endothelium in men with organic erectile dysfunction and to evaluate if they could be used to plan accurate PDE5i, non-invasive modalities of treatment. Methods In a prospective study, patients who were earlier evaluated and had vasculogenic ED and failed PDE5i treatment were clinically re-evaluated with questionnaires and CDDU. Additionally endothelial function and large arterial stiffness was assessed with the Vendys (reactive hyperaemia) &amp; Sphygmocor (central arterial pressure waveform analysis). Categories identified were, endothelial dysfunction by Vendys, Aortic augmentation index abnormality by Sphygmocor (age corrected), combined abnormality with poor scores with or without metabolic comorbidity. All three groups underwent LI-ESWT with low dose PDE5 inhibitors with a revised protocol. Results Validation of diagnostic tools was done in thirty five patients aged 48.24 ± 4.6 years (mean ± SD) with a mean IIEF score of 8.4 were evaluated by the three techniques. Positive predictive value (PPV) of the three techniques was similar, in the range 89-91% and a negative predictive value (NPV) around 41-45%. CDDU had highest sensitivity at 85%, but low specificity of 55%, followed by Sphygmocor® at 77% and Vendys at 75% and the latter techniques had better specificity of 70%. Parameter Penile Doppler SphygmoCor® Vendys® Value 95% CI Value 95% CI Value 95% CI Sensitivity 85 % 70.1-94.3 77.5 % 61.5-89.1 75 % 58.8-87.3 Specificity 55.6 % 21.2-86.3 70.0 % 34.7-93.3 70 % 34.7-93.3 Positive likelihood Ratio 1.91 0.91-4.02 2.58 0.99-6.76 2.50 0.95-6.55 Negative likelihood Ratio 0.27 0.11-0.69 0.32 0.16-0.65 0.36 0.18-0.70 PSV (N) IIEF Class (N) % &amp;lt; 25 (22) Severe (18) 81.82 44.00 Mod (3) 13.64 Mild (1) 4.55 25-30 (17) Severe (0) 0.00 34.00 Mod (14) 82.35 Mild (3) 17.65 CDDU Vs IIEF score The patients were grouped into three arms Vendys abnormality, Sphygmocor and combined; for Li-ESWT treatment (15 each). Pre and Post questionnaire based assessment was done and maximum improvement of IIEF was in the Alx abnormality arm with poor results in combined abnormality. Conclusions The aortic strain index and distensibility index were impaired in patients with ED. Vendys® SphygmoCor® are new tools in diagnosis of ED and superior to penile Doppler or questionnaire assessment. Li-ESWT is most beneficial in patients with Aortic elastic abnormality probably due shock wave effect on sheer stress of vessels by altering vessel wall pulsatality and resistivity index. Disclosure No

An Explainable Machine-Learning Model for Compensatory Reserve Measurement: Methods for Feature Selection and the Effects of Subject Variability.

Tracking vital signs accurately is critical for triaging a patient and ensuring timely therapeutic intervention. The patient's status is often clouded by compensatory mechanisms that can mask injury severity. The compensatory reserve measurement (CRM) is a triaging tool derived from an arterial waveform that has been shown to allow for earlier detection of hemorrhagic shock. However, the deep-learning artificial neural networks developed for its estimation do not explain how specific arterial waveform elements lead to predicting CRM due to the large number of parameters needed to tune these models. Alternatively, we investigate how classical machine-learning models driven by specific features extracted from the arterial waveform can be used to estimate CRM. More than 50 features were extracted from human arterial blood pressure data sets collected during simulated hypovolemic shock resulting from exposure to progressive levels of lower body negative pressure. A bagged decision tree design using the ten most significant features was selected as optimal for CRM estimation. This resulted in an average root mean squared error in all test data of 0.171, similar to the error for a deep-learning CRM algorithm at 0.159. By separating the dataset into sub-groups based on the severity of simulated hypovolemic shock withstood, large subject variability was observed, and the key features identified for these sub-groups differed. This methodology could allow for the identification of unique features and machine-learning models to differentiate individuals with good compensatory mechanisms against hypovolemia from those that might be poor compensators, leading to improved triage of trauma patients and ultimately enhancing military and emergency medicine.

103 Analysis of Arterial Blood Pressure Waveform Features in a Porcine Model of Burn and Resuscitation

Abstract Introduction Functional arterial blood pressure waveform (ABW) features are incompletely understood in the context of burn injury and resuscitation. In this work, we analyzed the variability of pulse pressure (PPV), systolic pressure (SPV), stroke volume (SVV), and five measures of heart rate variability (HRV) in time and frequency domains as potential indicators of burn resuscitation adequacy in a large total body surface area (TBSA) porcine model with varying degrees of intravenous fluids. Methods Data were collected from 21 anesthetized and mechanically-ventilated pigs (32±4 kg weight, 40% TBSA), which were instrumented for continuous hemodynamic monitoring for 24 hours. Urinary output (UO), hematocrit (HCT) and cardiac output (CO) were also measured at various time points. The animals were divided into Paradigm 1 (P1): no resuscitation (N=7); Paradigm 2 (P2): fluid titration to UO (N=8); and Paradigm 3 (P3): deliberate over-resuscitation with consistent high fluid rates (N=6). We calculated PPV, SPV, SVV, and five widely used HRV measures: normalized low-frequency power (NLF), high-frequency power (NHF), very-low-frequency power (VLF), low-frequency-high-frequency (LFHF) ratio, and the root-mean-squared of the duration difference in consecutive beats (RR-RMS). All features were averaged on an hourly basis and their potential in tracking reference CO and SV was investigated via linear regression and correlation analysis after calibrating the data to SV and CO on an individual basis. Results PPV, SPV, SVV, and RR-RMSE showed statistically distinguishable trends for different paradigms, as depicted in Figure 1, along with averaged trends for lab measurement. PPV, SPV, and SVV tracked the CO the best and were comparable to UO, however, SVV was far superior in tracking SV. A regression analysis between these four features and UO showed a very low level of agreement despite comparable tracking of SV and CO. HRV measures did not distinguish resuscitation paradigms and were inferior in tracking CO and similar in tracking SV to aforesaid features. Conclusions PPV, SPV, SVV, and RR-RMSE may potentially complement UO in the hemodynamic assessment of the burn patients and outperform other HRV measures in general. Future work will optimize the extraction of strategic informative features of ABW analysis in the various fluid status states post-burn injury. Applicability of Research to Practice Titrating burn resuscitation rates to have protocols including PPV, SPV, SVV, and RR-RMSE alongside other standard metrics may offer precision medicine strategies to fine-tune IV fluid rates.

Mock circulatory loop generated database for dynamic characterization of pressure-based cardiac output monitoring systems

Pulse contour cardiac output monitoring systems allow real-time and continuous estimation of hemodynamic variables such as cardiac output (CO) and stroke volume variation (SVV) by analysis of arterial blood pressure waveforms. However, evaluating the performance of CO monitoring systems to measure the small variations in these variables sometimes used to guide fluid therapy is a challenge due to limitations in clinical reference methods. We developed a non-clinical database as a tool for assessing the dynamic attributes of pressure-based CO monitoring systems, including CO response time and CO and SVV resolutions. We developed a mock circulation loop (MCL) that can simulate rapid changes in different parameters, such as CO and SVV. The MCL was configured to simulate three different states (normovolemic, cardiogenic shock, and hyperdynamic) representing a range of flow and pressure conditions. For each state, we simulated stepwise changes in the MCL flow and collected datasets for characterizing pressure-based CO systems. Nine datasets were generated that contain hours of peripheral pressure, central flow and pressure waveforms. The MCL-generated database is provided open access as a tool for evaluating dynamic characteristics of pressure-based CO algorithms and systems in detecting variations in CO and SVV indices. In an example application of the database, a CO response time of 10 s, CO and SVV resolutions with lower and upper limits of (−9.1%, 8.4%) and (−5.0%, 3.8%), respectively, were determined for a pressure-based CO benchtop system. This tool will support a more comprehensive assessment of pressure-based CO monitoring systems and algorithms.

An orthostatic load of 1/4G and 1/3G differentially activates vascular and cardiac components of cardiopulmonary reflexes

Introduction – Orthostatic load of varying degree affects cardiopulmonary reflexes and baroreflex. Cardiopulmonary reflexes initiate even before the baroreflex activation in response to volume changes in body caused by changed G load. The cardiopulmonary reflex has two effector components i.e., Heart and Vasculature. Lower body negative pressure (LBNP) is a non-invasive tool used to study the physiological effects of varying G loads. Aim &amp; Objective - The study was designed to explore the varying orthostatic load triggering cardiopulmonary reflexes. Material &amp; Methods - 33 healthy human volunteers were recruited. Continuous heart rate and blood pressure – Systolic, diastolic and mean blood pressure (measured as the area under curve of the pulse waveform) were recorded. Orthostatic load of 1/4G and 1/3G were chosen in order to prevent fall in blood pressure and baroreflex activation. The measurements were taken in supine resting state (0 mmHg), at -10 mmHg (1/4 G) and -15 mmHg (1/3G). Heart rate variability was calculated from the Lead II ECG with the help of Labchart Pro 8 ® software. Peripheral vascular resistance (PVR) was estimated indirectly from arterial pressure waveform. Statistical analysis was performed using Graphpad Prism. Results – At 1/4G of orthostatic load (-10 mmHg of oscillatory LBNP) activation of vascular component (PVR) of cardiopulmonary reflex was found with no changes in the cardiac component (HRV). At 1/3G of orthostatic load (-15 mmHg of oscillatory LBNP), there were activation of the cardiac component (LF:HRV, LF/HF:HRV) associated with further increase in the vascular component (PVR). Conclusion – Data suggests that 1/3G and 1/4G orthostatic load applied using LBNP despite no change in blood pressure, causes differential activation of vasculature and cardiac effector components of cardiopulmonary reflexes No funding received for carrying out the study This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Peripheral Intravenous Waveform Analysis Responsiveness to Subclinical Hemorrhage in a Rat Model.

Early detection and quantification of perioperative hemorrhage remains challenging. Peripheral intravenous waveform analysis (PIVA) is a novel method that uses a standard intravenous catheter to detect interval hemorrhage. We hypothesize that subclinical blood loss of 2% of the estimated blood volume (EBV) in a rat model of hemorrhage is associated with significant changes in PIVA. Secondarily, we will compare PIVA association with volume loss to other static, invasive, and dynamic markers. Eleven male Sprague Dawley rats were anesthetized and mechanically ventilated. A total of 20% of the EBV was removed over ten 5 minute-intervals. The peripheral intravenous pressure waveform was continuously transduced via a 22-G angiocatheter in the saphenous vein and analyzed using MATLAB. Mean arterial pressure (MAP) and central venous pressure (CVP) were continuously monitored. Cardiac output (CO), right ventricular diameter (RVd), and left ventricular end-diastolic area (LVEDA) were evaluated via transthoracic echocardiogram using the short axis left ventricular view. Dynamic markers such as pulse pressure variation (PPV) were calculated from the arterial waveform. The primary outcome was change in the first fundamental frequency (F1) of the venous waveform, which was assessed using analysis of variance (ANOVA). Mean F1 at each blood loss interval was compared to the mean at the subsequent interval. Additionally, the strength of the association between blood loss and F1 and each other marker was quantified using the marginal R2 in a linear mixed-effects model. PIVA derived mean F1 decreased significantly after hemorrhage of only 2% of the EBV, from 0.17 to 0.11 mm Hg, P = .001, 95% confidence interval (CI) of difference in means 0.02 to 0.10, and decreased significantly from the prior hemorrhage interval at 4%, 6%, 8%, 10%, and 12%. Log F1 demonstrated a marginal R2 value of 0.57 (95% CI 0.40-0.73), followed by PPV 0.41 (0.28-0.56) and CO 0.39 (0.26-0.58). MAP, LVEDA, and systolic pressure variation displayed R2 values of 0.31, and the remaining predictors had R2 values ≤0.2. The difference in log F1 R2 was not significant when compared to PPV 0.16 (95% CI -0.07 to 0.38), CO 0.18 (-0.06 to 0.04), or MAP 0.25 (-0.01 to 0.49) but was significant for the remaining markers. The mean F1 amplitude of PIVA was significantly associated with subclinical blood loss and most strongly associated with blood volume among the markers considered. This study demonstrates feasibility of a minimally invasive, low-cost method for monitoring perioperative blood loss.

Monitoring variability in parameter estimates for lumped parameter models of the systemic circulation using longitudinal hemodynamic measurements

BackgroundPhysics-based cardiovascular models are only recently being considered for disease diagnosis or prognosis in clinical settings. These models depend on parameters representing the physical and physiological properties of the modeled system. Personalizing these parameters may give insight into the specific state of the individual and etiology of disease. We applied a relatively fast model optimization scheme based on common local optimization methods to two model formulations of the left ventricle and systemic circulation. One closed-loop model and one open-loop model were applied. Intermittently collected hemodynamic data from an exercise motivation study were used to personalize these models for data from 25 participants. The hemodynamic data were collected for each participant at the start, middle and end of the trial. We constructed two data sets for the participants, both consisting of systolic and diastolic brachial pressure, stroke volume, and left-ventricular outflow tract velocity traces paired with either the finger arterial pressure waveform or the carotid pressure waveform.ResultsWe examined the feasibility of separating parameter estimates for the individual from population estimates by assessing the variability of estimates using the interquartile range. We found that the estimated parameter values were similar for the two model formulations, but that the systemic arterial compliance was significantly different (p < 10^{-6}) depending on choice of pressure waveform. The estimates of systemic arterial compliance were on average higher when using the finger artery pressure waveform as compared to the carotid waveform.ConclusionsWe found that for the majority of participants, the variability of parameter estimates for a given participant on any measurement day was lower than the variability both across all measurement days combined for one participant, and for the population. This indicates that it is possible to identify individuals from the population, and that we can distinguish different measurement days for the individual participant by parameter values using the presented optimization method.

The association between arterial compliance, as assessed by PTC1 and PTC2 from radial artery waveforms, and age, sex, and race/ethnicity.

There is limited literature on differences in arterial compliance, as assessed from arterial pressure waveforms, with age, sex, and race/ethnicity. PTC1 and PTC2 are indices of arterial compliance, which are derived from a Windkessel model of the waveform, relatively easy to obtain, and associated with cardiovascular disease. PTC1 and PTC2 were computed from radial artery waveforms from participants of the Multi-Ethnic Study of Atherosclerosis at baseline and again 10 years later. We evaluated the association of PTC1, PTC2, and 10-year change in PTC1 and PTC2 with age, sex, and race/ethnicity. Among 6245 participants in 2000-2002 (mean ± SD of age was 62 ± 10 years; 52% female; 38% White, 12% Chinese, 27% Black, and 23% Hispanic/Latino), means ± SDs for PTC1 and PTC2 were 394 ± 334 and 94 ± 46 ms. After adjustment for cardiovascular disease risk factors, mean PTC2 was 1.1 ms (95% confidence interval: 1.0, 1.2) lower (arterial stiffness was greater) per year older age, was 22 ms (19, 24) lower for females, and varied by race/ethnicity ( P < 0.001; e.g., 5 ms lower for Blacks compared with Whites), although the differences were smaller at older ages ( P < 0.001 for age-sex, P < 0.001 for age-race/ethnicity interactions). Among 3701 participants with repeat measurements in 2010-2012, arteries had stiffened (mean ± SD 10-year decrease in PTC2: 13 ± 46 ms) consistent with cross-sectional age-trend and tended to stiffen less for females and Blacks consistent with cross-sectional age-interactions. Differences in arterial compliance by age, sex, and race/ethnicity lend support to identify and act on societal factors that may drive health disparities.

Is Continuous Intraoperative Monitoring of Mean Arterial Pressure as Good as the Hypotension Prediction Index Algorithm?: Research Letter.

Is Continuous Intraoperative Monitoring of Mean Arterial Pressure as Good as the Hypotension Prediction Index Algorithm?: Research Letter.

A Scoping Review of Cerebral Doppler Arterial Waveforms in Infants.

Cerebral Doppler ultrasound has been an important tool in pediatric diagnostics and prognostics for decades. Although the Doppler spectrum can provide detailed information on cerebral perfusion, the measured spectrum is often reduced to simple numerical parameters. To help pediatric clinicians recognize the visual characteristics of disease-associated Doppler spectra and identify possible areas for future research, a scoping review of primary studies on cerebral Doppler arterial waveforms in infants was performed. A systematic search in three online bibliographic databases yielded 4898 unique records. Among these, 179 studies included cerebral Doppler spectra for at least five infants below 1 y of age. The studies describe variations in the cerebral waveforms related to physiological changes (43%), pathology (62%) and medical interventions (40%). Characteristics were typically reported as resistance index (64%), peak systolic velocity (43%) or end-diastolic velocity (39%). Most studies focused on the anterior (59%) and middle (42%) cerebral arteries. Our review highlights the need for a more standardized terminology to describe cerebral velocity waveforms and for precise definitions of Doppler parameters. We provide a list of reporting variables that may facilitate unambiguous reports. Future studies may gain from combining multiple Doppler parameters to use more of the information encoded in the Doppler spectrum, investigating the full spectrum itself and using the possibilities for long-term monitoring with Doppler ultrasound.

PD33-10 NON-INVASIVE OPTICAL DETERMINATION OF DETRUSOR PRESSURE RELATED TO DETRUSOR OVERACTIVITY

You have accessJournal of UrologyCME1 Apr 2023PD33-10 NON-INVASIVE OPTICAL DETERMINATION OF DETRUSOR PRESSURE RELATED TO DETRUSOR OVERACTIVITY Lynn Stothers, Andrew Macnab, Naser Hakimi, W. N. J. M. Colier, P. Pourabbassi, and M. Maresse Lynn StothersLynn Stothers More articles by this author , Andrew MacnabAndrew Macnab More articles by this author , Naser HakimiNaser Hakimi More articles by this author , W. N. J. M. ColierW. N. J. M. Colier More articles by this author , P. PourabbassiP. Pourabbassi More articles by this author , and M. MaresseM. Maresse More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003326.10AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Gold standard urodynamic studies use invasive methods and artificial filling of the bladder to determine detrusor pressure, a critical physiologic measure in determining care for lower urinary tract symptoms (LUTS). The benefits of non-invasive measurement of detrusor pressure (Pdet) include natural filling observations & the potential for a homebased wearable with real time data to determine both self-care and monitoring. Aim: to develop a wearable optical based technology to relate non-invasively measured changes in Pdet during natural filling. METHODS: A 10 x 10 cm optical grid using light emitting diodes (LED’s) (750 nm – 950 nm) was engineered & positioned suprapubically during simultaneous multichannel urodynamics (UDS). LED’s were paired with photodetectors, sampling at 50Hz from long (deep) and short (superficial) channels facilitating optical output compared to variations in Pdet. Output: Arterial pulse waveform changes in chromophore concentration related to variations in detrusor oxygenation (O2Hb), & fluctuations in the absorption of photons at 950nm (H20) related to CMG volume increases. Peak & trough envelopes were computed with Hilbert transformation and a filtered moving average was used mathematically. RESULTS: N=25 (5 controls no LUTS & 20 NLUTD female=N=5 age 64-82 yrs ASIA A, B & D; male=N=15 age 33 – 79 yrs being ASIA A,B,C & D. NLUTD management included: N=4 subjects using clean intermittent catheterization (CIC), 2 condom drainage, 5 using combinations of CIC and spontaneous voiding, 4 spontaneous voiding only. No subjects used anticholinergics, B 3 agonists or prior intra detrusor botulinum toxin. Controls: natural filling and uroflow, no LUTS on IPSS or UGDI, no prior GU surgery, volumes >150cc, repeated filling & emptying for internal consistency measures. CONCLUSIONS: A prototype wearable able to derive a real-time, non-invasive measure reflecting detrusor pressure was successfully prototyped. If further research confirms the ability of an optical parameter derived in this way to mirror variations in detrusor pressure, benefits that would accrue include: more frequent assessment than is possible with invasive UDS, & the ability to monitor changes in pressure continuously in an at risk population (e.g. NLUTD at risk for autonomic dysreflexia). Source of Funding: Craig H Neilsen Foundation © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e917 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Lynn Stothers More articles by this author Andrew Macnab More articles by this author Naser Hakimi More articles by this author W. N. J. M. Colier More articles by this author P. Pourabbassi More articles by this author M. Maresse More articles by this author Expand All Advertisement PDF downloadLoading ...

Relationship between combat-related traumatic injury and ultrashort term heart rate variability in a UK military cohort: findings from the ADVANCE study

IntroductionCombat-related traumatic injury (CRTI) has been linked to an increased cardiovascular disease (CVD) risk. The long-term impact of CRTI on heart rate variability (HRV)—a robust CVD risk marker—has not been...

A Machine Learning Approach to the Non-Invasive Estimation of Continuous Blood Pressure Using Photoplethysmography

Blood pressure is an important vital sign that sometimes requires continuous measurement. The current methods include cuff measurements (manual auscultation and oscillometric techniques) for non-continuous measurement and invasive arterial cannulation for continuous measurement. The use of photoplethysmography as a cuffless, non-invasive, and continuous blood pressure measurement system is investigated through the use of four neural networks. These predict the systolic blood pressure, diastolic blood pressure, mean arterial blood pressure, and waveform shape. The models are trained on 890 h of data from 1669 patients in the MIMIC-III database. Feature-trained artificial neural networks predict the systolic blood pressure to 5.26 ± 6.53 mmHg (mean error ± standard deviation), the diastolic blood pressure to 2.96 ± 3.31 mmHg, and the mean arterial pressure to 3.27 ± 3.55 mmHg. These are used to shift and scale the predicted waveform, allowing the waveform prediction neural network to optimise for the wave shape rather than the amplitude. The waveform prediction has 86.4% correlation with the actual arterial blood pressure waveform. All results meet international clinical blood pressure measurement standards and could potentially change how blood pressure is measured in both clinical and research settings. However, more data from healthy individuals and analysis of the models’ biases based on clinical features is required.

Accuracy of Cardiac Output Measured by Fourth-Generation FloTrac and LiDCOrapid, and Their Characteristics Regarding Systemic Vascular Resistance in Patients Undergoing Cardiac Surgery

The clinical use of less-invasive devices that calculate the cardiac output from arterial pressure waveform is increasing. The authors aimed to evaluate the accuracy and characteristics of the systemic vascular resistance index (SVRI) of the cardiac index measured by 2 less-invasive devices, fourth-generation FloTrac (CIFT) and LiDCOrapid (CILR), compared with the intermittent thermodilution technique, using a pulmonary artery catheter (CITD). This was a prospective observational study. This study was conducted at a single university hospital. Twenty-nine adult patients undergoing elective cardiac surgery. Elective cardiac surgery was used as an intervention. Hemodynamic parameters, CIFT, CILR, and CITD, were measured after the induction of general anesthesia, at the start of cardiopulmonary bypass, after completion of weaning from cardiopulmonary bypass, 30 minutes after weaning, and at sternal closure (135 measurements in total). The CIFT and CILR had moderate correlations with CITD (r=0.62 and 0.58, respectively). Compared with CITD, CIFT, and CILR had a bias of -0.73 and -0.61 L/min/m2, limit of agreement of -2.14-to-0.68 L/min/m2 and -2.42-to-1.20 L/min/m2, and percentage error of 39.9% and 51.2%, respectively. Subgroup analysis for evaluating SVRI characteristics showed that the percentage errors of CIFT and CILR were 33.9% and 54.5% in low SVRI (<1,200 dyne×s/cm5/m), 37.6% and 47.9% in moderate SVRI (1,200-1,800 dyne×s/cm5/m), 49.3% and 50.6% in high SVRI (>1,800 dyne·s/cm5/m2), respectively. The accuracy of CIFT or CILR was not clinically acceptable for cardiac surgery. Fourth-generation FloTrac was unreliable in high SVRI. LiDCOrapid was inaccurate across a broad range of SVRI, and minimally affected by SVRI.