Non-invasive Arterial Pressure Research Articles

Agreement between non-invasive and invasive arterial blood pressure during surgery in the prone position: an error grid analysis.

Prone position has recently gained renewed importance as a treatment for acute respiratory distress syndrome and spine and brain surgeries. Our study aimed to perform an error grid analysis to examine the clinical discrepancies between arterial blood pressure (ABP) and non-invasive blood pressure (NIBP) in the prone position and to investigate the risk factors influencing these differences. Error grid analysis was performed retrospectively on 1389 pairs of 100 consecutive prone positioning cases. This analysis classifies the difference between the two methods into five clinically relevant zones, from "no risk" to "dangerous risk". Additionally, multivariable ordinal logistic regression analysis was conducted to evaluate the relationship between the risk zones of mean blood pressure (MBP), as classified by error grid analysis and the covariate of interest. Error grid analysis showed that the proportions of measurement pairs in risk zones A-E for systolic blood pressure were 96.8%, 3.2%, 0.1%, 0%, and 0%, respectively. In contrast, the MBP proportions were 74.0%, 25.1%, 0.9%, 0.1%, and 0%. Multivariable ordinal logistic regression analysis revealed that the position of arms (next to the head) was a significant factor (adjusted odds ratio: 4.35, 95% CI: 2.38-8.33, P < 0.001). Error grid analysis revealed a clinically unacceptable discrepancy between ABP and NIBP for MBP during prone positioning surgery. The position of the arms next to the head was associated with increased clinical discrepancy between the two MBP measurement methods.

Vascular Aging Entails Arterial Dilatation in Addition to Increased Arterial Stiffness

Introduction: The increase in arterial blood pressure occurring with aging is considered an important risk factor for end-organ damage in, among others, the brain. How exactly this risk emerges is largely unknown. Methods: We investigated the effect of aging on middle cerebral flow velocity (MCAFV) and noninvasive arterial blood pressure (NIBP) in 105 healthy volunteers aged 18 to 82 years. Both pulsatile signals were analyzed determining the first (Sys1) and second systolic peak (Sys2) and the diastolic flow velocity 560 ms after stroke onset (D560). Results: For NIBP, a linear increase was found with aging for Sys2 and D560 (0.72 and 0.14 mm Hg/year, respectively) but not for Sys1. For MCAFV, a linear decrease was found with aging for all variables, being more rapid for Sys1 than for Sys2 or D560 (−0.94, −0.41, and −0.54 cm/s/year, respectively). Both signals change from Sys1 dominant in young adults to increasingly Sys2 dominant in the elderly. Discussion: That MCAFV decreases with aging, whereas NIBP increases can best be explained by assuming arterial dilatation. Apart from the generally accepted increase in arterial stiffness, arterial dilatation may be an important additional factor in vascular aging: the loss of elastin allows arteries to dilate until restricted by arterial collagen. Conclusion: Normal values collected in this study support protocols for non-invasive monitoring that require a correction for age.

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.

Comparison of the effects of intranasal and intramuscular midazolam–butorphanol–ketamine on intraocular pressure, tear production and sedation in New Zealand White rabbits

ObjectiveTo compare the effects of intranasal (IN) and intramuscular (IM) midazolam–butorphanol–ketamine on intraocular pressure (IOP), tear production (TP) and sedation in rabbits. Study designProspective, randomized, crossover experimental study. AnimalsFourteen male New Zealand White rabbits, aged 1–2 years, body mass 3.1 ± 0.8 kg (mean ± standard deviation). MethodsRabbits were administered midazolam (1 mg kg–1), butorphanol (1.5 mg kg–1) and ketamine (5 mg kg–1) via IN and IM routes. IOP, TP and sedation scores were assessed at 0 (before drug administration), 5, 15, 30, 45 and 60 minutes after drug administration. Heart rate (HR), respiratory rate (fR), rectal temperature (RT), noninvasive mean arterial blood pressure (MAP) and peripheral hemoglobin oxygen saturation (SpO2) were simultaneously recorded until 45 minutes after drug administration. The onset and duration of sedation and sedation scores were recorded. ResultsDrug delivery route had no significant impact on mean IOP (p = 0.271) or TP (p = 0.062), and there were no significant changes over time for IOP (p = 0.711) or TP (p = 0.372). Similarly, delivery route had no significant impact on HR (p = 0.747), fR (p = 0.872), RT (p = 0.379), MAP (p = 0.217) and SpO2 (p = 0.254). Sedation onset was faster with IN (3.0 ± 1.0 minutes) than with IM administration (4.9 ± 0.7 minutes) (p = 0.011), but sedation duration was significantly longer with IM (52.6 ± 7.2 minutes) than with IN delivery (30.7 ± 6.8 minutes) (p = 0.004). There was no significant difference in sedation scores between the two delivery routes at any of the recorded time points. Conclusions and clinical relevanceThe combination of midazolam–butorphanol–ketamine had minimal impact on physiological and ocular variables regardless of the route of administration, whereas IN drug administration led to a shorter onset and duration of action than IM administration.

Comparison of cardiopulmonary effects of propofol, ketamine–propofol and isoflurane anesthesia in the domestic chicken (Gallus gallus domesticus)

ObjectiveTo compare the effects of propofol, ketamine–propofol and isoflurane, at similar anesthetic depth, on cardiopulmonary variables in unpremedictated chickens. Study designProspective, randomized, crossover experimental trial. AnimalsA total of 10 male Leghorn domestic chickens, aged 3 months and body mass 1.4–2.0 kg. MethodsBirds were randomly assigned to each of three anesthetic protocols, 7 days apart: intravenous propofol, intravenous ketamine–propofol or isoflurane. Anesthesia was induced (indicated by loss of righting reflex and tracheal intubation) and maintained with propofol (10 mg kg–1 minute–1, then 1.1 mg kg–1 minute–1), ketamine–propofol (5 mg mL–1 ketamine and 5 mg mL–1 propofol combined; 10 mg kg–1 minute–1, then 1.1 mg kg–1 minute–1) or isoflurane [5% vaporizer setting initially, then end-tidal concentration (Fe′Iso) of 2%] for 65 minutes. Anesthesia was maintained at a similar anesthetic depth based upon positive or negative responses to toe pinch. Heart rate (HR), respiratory rate (fR), noninvasive arterial blood pressure and arterial blood gases were measured during anesthesia. Propofol or ketamine–propofol infusion rates and Fe′Iso required to prevent movement in response to a noxious stimulus and recovery times were recorded. ResultsAnesthesia induction dose was 9.0 ± 0.8 (mean ± SD) and 12.2 ± 0.3 mg kg–1 for propofol and ketamine–propofol, respectively. Propofol and ketamine–propofol infusion rates and Fe′Iso required to prevent movement in response to the noxious stimulus were 0.88 ± 0.14 mg kg–1 minute–1, 0.92 ± 0.14 mg kg–1 minute–1 and 1.45 ± 0.28%, respectively. Cardiopulmonary variables remained clinically acceptable, but ketamine–propofol was associated with a significantly higher HR (p = 0.0001) and lower fR (p = 0.0001). Time to extubation did not differ among treatments. Conclusions and clinical relevanceCardiovascular and respiratory variables were maintained within normal ranges in all treatments. Coadministration of ketamine with propofol significantly reduced the induction and maintenance dose of propofol.

Propofol-sparing and hemodynamic effects of guaifenesin in sheep

ObjectiveTo evaluate the propofol-sparing and hemodynamic effects of guaifenesin administered for co-induction of anesthesia in sheep. Study designProspective, blinded, two-way crossover experimental study. AnimalsThirteen healthy adult female sheep. MethodsAnesthesia was induced without premedication with intravenous (IV) guaifenesin 5% at 100 mg kg–1 (GGE) or an equivalent volume of physiologic saline (SAL), followed by IV propofol at a controlled rate (1 mg kg–1 min–1). Heart rate (HR), respiratory rate and oscillometric noninvasive arterial blood pressure (NIBP) were recorded at baseline after co-induction administration, following endotracheal intubation and every 2 minutes thereafter for 10 minutes. Propofol doses required to achieve intubation after each co-induction treatment were compared by independent Student’s t-test. Values of p < 0.05 were considered statistically significant. ResultsThe propofol dose required (mean ± standard deviation) to achieve intubation was significantly lower (p = 0.001) in the GGE treatment (3.40 ± 0.74 mg kg–1) than in the SAL treatment (5.94 ± 1.09 mg kg–1). HR was increased after anesthetic induction compared with baseline in both treatments. HR was generally lower in the GGE treatment than in the SAL treatment. NIBP did not vary between GGE and SAL treatments. Conclusions and clinical relevanceGuaifenesin, when administered as a co-induction agent with propofol in sheep, reduces propofol dose requirements and maintains hemodynamic variables within a clinically acceptable range.

A manual watch to monitor non-invasive blood pressure, arterial pressure, and measure oscillations within the bloodstream continuously

A manual watch to monitor non-invasive blood pressure, arterial pressure, and measure oscillations within the bloodstream continuously

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.

Finger photopletysmography detects early acute blood loss in compensated blood donors: a pilot study

Objective. Diagnosis of incipient acute hypovolemia is challenging as vital signs are typically normal and patients remain asymptomatic at early stages. The early identification of this entity would affect patients’ outcome if physicians were able to treat it precociously. Thus, the development of a noninvasive, continuous bedside monitoring tool to detect occult hypovolemia before patients become hemodynamically unstable is clinically relevant. We hypothesize that pulse oximeter’s alternant (AC) and continuous (DC) components of the infrared light are sensitive to acute and small changes in patient’s volemia. We aimed to test this hypothesis in a cohort of healthy blood donors as a model of slight hypovolemia. Approach. We planned to prospectively study blood donor volunteers removing 450 ml of blood in supine position. Noninvasive arterial blood pressure, heart rate, and finger pulse oximetry were recorded. Data was analyzed before donation, after donation and during blood auto-transfusion generated by the passive leg-rising (PLR) maneuver. Main results. Sixty-six volunteers (44% women) accomplished the protocol successfully. No clinical symptoms of hypovolemia, arterial hypotension (systolic pressure < 90 mmHg), brady-tachycardia (heart rate <60 and >100 beats-per-minute) or hypoxemia (SpO2 < 90%) were observed during donation. The AC signal before donation (median 0.21 and interquartile range 0.17 a.u.) increased after donation [0.26(0.19) a.u; p < 0.001]. The DC signal before donation [94.05(3.63) a.u] increased after blood extraction [94.65(3.49) a.u; p < 0.001]. When the legs’ blood was auto-transfused during the PLR, the AC [0.21(0.13) a.u.; p = 0.54] and the DC [94.25(3.94) a.u.; p = 0.19] returned to pre-donation levels. Significance. The AC and DC components of finger pulse oximetry changed during blood donation in asymptomatic volunteers. The continuous monitoring of these signals could be helpful in detecting occult acute hypovolemia. New pulse oximeters should be developed combining the AC/DC signals with a functional hemodynamic monitoring of fluid responsiveness to define which patient needs fluid administration.

Comparative Analysis of the Hemodynamic Effects of Remimazolam and Propofol During General Anesthesia: A Retrospective Study.

Hypotension is common during anesthesia induction. However, minimal hemodynamic effects of remimazolam anesthesia have been reported. We hypothesized that remimazolam would have weaker hemodynamic effects than would propofol. To test this, we simultaneously evaluated the hemodynamics using the estimated continuous cardiac output (esCCO) system and heart rate variability (HRV) during anesthesia induction. This was a single-center, observational, retrospective study of patients undergoing dental surgery under general anesthesia between 2020 and 2022. Seventy patients were divided into two groups: remimazolam (R group; n=34) and propofol (P group; n=36). The information obtained from the anesthesia records, patient information, esCCO system parameters, and HRV were integrated and analyzed. The percentages of various parameters were set to 100% for the pre-induction phase as the baseline. The %MAP (noninvasive mean arterial blood pressure) decreased over a narrower range in the R compared to the P group (-17.8% (-26.3%, -11.9%) vs. -22.6% (-32.9%, -17.0%); P=0.039). The %HR (heart rate) increased significantly in the R group and decreased in the P group (+10.7% (+6.5%, +18.6%) vs. -6.5% (-14.5%, +8.4%); P<0.01). The %SVesCCO(stroke volume calculated using the esCCO system) decreased significantly in both groups, but the R group showed a smaller difference compared to the P group (- 5.1% (-7.7%, -2.1%) vs. -10.0% (-13.8%, -5.6%); P<0.01). The rates of change in %LF nu (normalized unit of low frequency) and %HF nu (normalized unit of high frequency) were lower for the R than for the P group, although the difference was not significant (+6.8% (-14.5%, 32.4%) vs. +9.2% (-7.2%, +59.7%), P=0.30; +7.9% (-51.0%, +66.9%) vs. +22.8% (-26.1%, +61.6%), P=0.57). Remimazolam demonstrated a lower MAP reduction rate than propofol. A compensatory increase in HR occurred with a decrease in stroke volume. However, the HR increase was not attributable to the autonomic nervous system.

A randomized clinical trial comparing the efficacy of lidocaine administered intravenously, intranasally or as infraorbital nerve block in dogs undergoing rostral rhinosocopy

ObjectiveTo compare the efficacy of lidocaine administered intravenously, intranasally or as an infraorbital nerve block in dogs undergoing rostral rhinoscopy. Study designRandomized clinical trial. AnimalsA total of 43 client-owned dogs. MethodsAfter premedication with medetomidine 0.01 mg kg–1 and methadone 0.2 mg kg–1 intramuscularly, anaesthesia was induced with propofol and maintained with isoflurane in oxygen. Dogs were randomly allocated to receive 2 mg kg–1 of 2% lidocaine as a bilateral infraorbital nerve block (INB) via the caudal intraoral approach, via bilateral topical intranasal administration (TIA) or as an intravenous bolus (IVB). At 5 minutes following lidocaine administration, responses to rhinoscopy (RR) and biopsies (RB) were evaluated using a simple scoring system (0: no reaction; 1: reaction). Response to the rhinoscopy in the recovery period (RE) was recorded. Recovery quality was scored using a simple descriptive score. Heart rate, respiratory rate and noninvasive arterial blood pressure were recorded. Intravenous (IV) fentanyl 0.001 mg kg-1 was administered if an increase > 20% in any variable occurred. Gross movement was attenuated using propofol 0.5 mg kg–1 IV. Scores were analysed using the Chi-square test with Monte Carlo method. Cardiorespiratory changes among and overtime between groups were compared using one-way anova and one-way anova for repeated measures, respectively, or the correspondent non-parametric tests; p < 0.05. ResultOf the 43 dogs, 42 completed the study. No statistically significant differences were detected in either physical reactions or changes in cardiorespiratory variables for RR, RB, RE or recovery quality, although RB tended to be higher in group TIA (7/10 versus 1/10 INB and 3/13 IVB).Various cardiorespiratory variables changed overtime within groups. Conclusions and clinical relevanceIn dogs, all three investigated techniques attenuated responses during rostral rhinoscopy in dogs, although INB and IVB were more efficacious when biopsies were taken.

Use of a Non-invasive Central Arterial Pressure Waveform Analysis Device in Stroke Patients – A Feasibility Study (P9-5.008)

Use of a Non-invasive Central Arterial Pressure Waveform Analysis Device in Stroke Patients – A Feasibility Study (P9-5.008)

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.

Finger cuff versus invasive and noninvasive arterial pressure measurement in pregnant patients with obesity.

Pregnant patients with obesity may have compromised noninvasive blood pressure (NIBP) measurement. We assessed the accuracy and trending ability of the ClearSight™ finger cuff (FC) with invasive arterial monitoring (INV) and arm NIBP, in obese patients having cesarean delivery. Participants were aged ≥18 years, ≥34 weeks gestation, and body mass index (BMI) ≥ 40 kg m-2. FC, INV, and NIBP measurements were obtained across 5-min intervals. The primary outcome was agreement of FC measurements with those of the reference standard INV, using modified Bland-Altman plots. Secondary outcomes included comparisons between FC and NIBP and NIBP versus INV, with four-quadrant plots performed to report discordance rates and evaluate trending ability. Twenty-three participants had a median (IQR) BMI of 45 kg m-2 (44-48). When comparing FC and INV the mean bias (SD, 95% limits of agreement) for systolic blood pressure (SBP) was 16 mmHg (17, -17.3 to 49.3 mmHg), for diastolic blood pressure (DBP) -0.2 mmHg (10.5, -20.7 to 20.3), and for mean arterial pressure (MAP) 5.2 mmHg (11.1, -16.6 to 27.0 mmHg). Discordance occurred in 54 (26%) pairs for SBP, 41 (23%) for DBP, and 41 (21.7%) for MAP. Error grid analysis showed 92.1% of SBP readings in Zone A (no-risk zone). When comparing NIBP and INV, the mean bias (95% limits of agreement) for SBP was 13.0 mmHg (16.7, -19.7 to 29.3), for DBP 5.9 mmHg (11.9, -17.4 to 42.0), and for MAP 8.2 mmHg (11.9, -15.2 to 31.6). Discordance occurred in SBP (84 of 209, 40.2%), DBP (74 of 187, 39.6%), and MAP (63 of 191, 33.0%). The FC and NIBP techniques were not adequately in agreement with INV. Trending capability was better for FC than NIBP. Clinically important differences may occur in the setting of the perfusion-dependent fetus.

Myths and methodologies: Assessment of dynamic cerebral autoregulation by the mean flow index.

The mean flow index-usually referred to as Mx-has been used for assessing dynamic cerebral autoregulation (dCA) for almost 30years. However, concerns have arisen regarding methodological consistency, construct and criterion validity, and test-retest reliability. Methodological nuances, such as choice of input (cerebral perfusion pressure, invasive or non-invasive arterial pressure), pre-processing approach and artefact handling, significantly influence mean flow index values, and previous studies correlating mean flow index with other established dCA metrics are confounded by inherent methodological flaws like heteroscedasticity, while the mean flow index also fails to discriminate individuals with presumed intact versus impaired dCA (discriminatory validity), and its prognostic performance (predictive validity) across various conditions remains inconsistent. The test-retest reliability, both within and between days, is generally poor. At present, no single approach for data collection or pre-processing has proven superior for obtaining the mean flow index, and caution is advised in the further use of mean flow index-based measures for assessing dCA, as current evidence does not support their clinical application.

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.

Echocardiographic and hemodynamic effects of alfaxalone or dexmedetomidine based sedation protocols in cats with hypertrophic cardiomyopathy: a pilot study

ObjectiveTo report the effects of alfaxalone and dexmedetomidine based sedation protocols on echocardiographic and hemodynamic variables in cats with hypertrophic cardiomyopathy (HCM) during sedation and inhalational anesthesia. Study designProspective, randomized, experimental study. AnimalsA group of 10 client-owned cats with subclinical HCM. MethodsCats were administered one of two sedative intramuscular combinations: protocol ABM (alfaxalone 2 mg kg–1, butorphanol 0.4 mg kg–1, midazolam 0.2 mg kg–1; n = 5) or protocol DBM (dexmedetomidine 8 μg kg–1, butorphanol 0.4 mg kg–1, midazolam 0.2 mg kg–1; n = 5). General anesthesia was induced with intravenous alfaxalone and maintained with isoflurane in oxygen. Echocardiographic variables and noninvasive arterial blood pressures were obtained before sedation, following sedation, and during inhalational anesthesia. Sedation scores and alfaxalone induction dose requirements were recorded. Descriptive statistics are reported for cardiovascular variables. ResultsDuring sedation, echocardiographic and hemodynamic variables remained within normal limits with protocol ABM, whereas protocol DBM was characterized by bradycardia, low cardiac index and elevated blood pressure. During isoflurane anesthesia, both protocols demonstrated similar hemodynamic performance, with heart rates of 98 ± 12 and 89 ± 11 beats min–1, cardiac index values of 68 ± 17 and 47 ± 13 mL min–1 kg–1 and Doppler blood pressures of 72 ± 15 and 79 ± 20 mmHg with protocols ABM and DBM, respectively. A reduction in myocardial velocities were also observed during atrial and ventricular contraction with both protocols during isoflurane anesthesia. Conclusions and clinical relevanceAn alfaxalone based protocol offered hemodynamic stability during sedation in cats with HCM; however, both dexmedetomidine and alfaxalone based protocols resulted in clinically relevant hemodynamic compromise during isoflurane anesthesia. Further studies are required to determine optimal sedative and anesthetic protocols in cats with HCM.

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.

Correlation between non-invasive measurements and intracardiac pressures using machine learning techniques

Abstract Background Solutions targeting early recognition of congestion in heart failure (HF) patients have the potential to prevent readmissions and can thus significantly reduce the burden on HF care. A gold standard measure of congestion is the invasively measured pulmonary capillary wedge pressure (PCWP). However, the invasive nature and accessibility of this measurement limits its clinical use. Non-invasive approximation of the PCWP using biosensing wearables could be a promising replacement for HF monitoring. Purpose The primary aim of this retrospective study was to create a model that estimates the PCWP based on non-invasive measurements of vital signs using both traditional statistics and machine learning (ML) techniques. Methods The study cohort consisted of right-sided heart catheterizations between 23/6/2017 and 19/8/2022. The following models were used: linear regression or classification, k-nearest neighbors, random forest, gradient boosting and multilayer perceptron. The outcome measure for the regression models was the continuous PCWP as measured during the catheterization. The two outcome classes for the classification models were low (&amp;lt;12 mmHg) and high (≥12 mmHg) PCWP. Non-invasive mean arterial blood pressure (MAP), saturation, heart rate, weight and temperature measured at most 72 hours before or after the catheterization were collected as the features for the models. Additionally, ECG-signals acquired during the catheterization were used to calculate the heart rate variability (HRV). The data was split in a validation (20%) and training (80%) data set. The models were built based on the training set and then applied on the validation set to determine the coefficient of determination (R2) for the regression models and the AUC of the ROC for the classification models. Results A total of 859 catheterizations were included of which 31.2% had HF as primary diagnosis. Average age of the cohort was 59 ± 14 years and 52.2% were male. In the HF group, the features with the highest correlation with the PCWP were the HRV and gender (Table 1). All the used regression techniques resulted in low R2 values of up to 0.10 and the classification techniques in AUC of the ROC values of up to 0.61 (Table 2). Conclusion In the current study, PCWP could not be approximated with non-invasive measurements using traditional statistics and ML techniques. These findings support the notion that traditional measures for monitoring HF are poorly correlated with hemodynamic parameters. Perhaps repeated measurements over time could overcome the shortcomings of a single vital signs measurement for congestion evaluation. Future prospective research is needed to evaluate the potential of wearable devices measuring trends over a longer period and their potential in predicting hemodynamics.

Abstract 17573: Reliability of Non-Invasive Arterial Pressure Monitoring via ClearSight System™ During Cardiac Ablation and Transvenous Pacemaker Lead Removal

Background: Invasive arterial catheter (IAC) placement can lead to hematoma, vessel occlusion, pain and &amp; procedure delay. The ClearSight System™ (CSS) is a non-invasive blood pressure (NIBP) device that measures beat-to-beat arterial pressures (AP) via a finger cuff. The validity of CSS during cardiac ablation &amp; transvenous pacemaker lead removal has not been described. Therefore, we performed a single center observational study to validate AP monitoring by CSS compared to IAC in such patients (pts). Methods: Pts undergoing cardiac ablation or lead removal from June-November 2022 were included. AP was simultaneously measured via CSS &amp; IAC. Measurements were compared using Bland-Altman analysis. Acceptable bias &amp; precision (standard deviation) were defined as &lt;5 mm Hg &amp; &lt;8 mm Hg respectively based on Association for the Advancement of Medical Instrumentation standards. An exploratory analysis on impacts of BMI, sex, &amp; type of procedure on validity of CSS was also assessed. Results: Paired AP measurements were available for 61 pts (6967 paired measurements). Median age was 67 (IQR 60.5-73.5), BMI 29.2 (IQR 26.1-37.1) &amp; 31% of pts were female. Procedures included atrial fibrillation ablation (n=32), SVT ablation (n=13), lead extraction (n=9), &amp; VT ablation (n=7). Bland-Altman analysis comparing AP via CSS vs IAC showed that the CSS overestimated systolic arterial pressure (SAP) &amp; underestimated both diastolic arterial pressure (DAP) &amp; mean arterial pressure (MAP). Mean bias was 4.2 ± 12.9 (SAP), -4.99 ± 9.2 (DAP) &amp; -2.4 ± 11.78 (MAP) (Figure 1). Exploratory analysis showed that CSS was not interchangeable with IAC monitoring regardless of subgroup (MAP male sex -1.9 ± 11.1; BMI ≥30 -2.7 ± 9.7; ablation -1.8 ± 12.2). Conclusion: Continuous NIBP monitoring via CSS was not interchangeable with IAC monitoring in pts undergoing cardiac ablation &amp; lead extraction.