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Purpose: Net ultrafiltration (UFNET) during continuous renal replacement therapy (CRRT) can control fluid balance (FB), but is usually 0 ml·h−1 in patients with vasopressors due to the risk of hemodynamic instability associated with CRRT (HIRRT). We evaluated a UFNET strategy adjusted by functional hemodynamics to control the FB of patients with vasopressors, compared to the standard of care. Methods: In this randomized, controlled, open-label, parallel-group, multicenter, proof-of-concept trial, adults receiving vasopressors, CRRT since ≤ 24 h and cardiac output monitoring were randomized (ratio 1:1) to receive during 72 h a UFNET ≥ 100 ml·h−1, adjusted using a functional hemodynamic protocol (intervention), or a UFNET ≤ 25 ml·h−1 (control). The primary outcome was the cumulative FB at 72 h and was analyzed in patients alive at 72 h and in whom monitoring and CRRT were continuously provided (modified intention-to-treat population [mITT]). Secondary outcomes were analyzed in the intention-to-treat (ITT) population. Results: Between June 2021 and April 2023, 55 patients (age 69 [interquartile range, IQR: 62; 74], 35% female, Sequential Organ Failure Assessment (SOFA) 13 [11; 15]) were randomized (25 interventions, 30 controls). In the mITT population, (21 interventions, 24 controls), the 72 h FB was −2650 [−4574; −309] ml in the intervention arm, and 1841 [821; 5327] ml in controls (difference: 4942 [95% confidence interval: 2736–6902] ml, P < 0.01). Hemodynamics, oxygenation and the number of HIRRT at 72 h, and day-90 mortality did not statistically differ between arms. Conclusion: In patients with vasopressors, a UFNET fluid removal strategy secured by a hemodynamic protocol allowed active fluid balance control, compared to the standard of care. [ABSTRACT FROM AUTHOR]

PurposeThe pressure recording analytical method (PRAM) monitor is a non-invasive pulse contour cardiac output (CO) device that cannot be considered interchangeable with the gold standard for CO estimation. It, however, generates additional hemodynamic indices that need to be evaluated. Our objective was to investigate the performance of a multiparametric predictive score based on a combination of several parameters generated by the PRAM monitor to predict fluid responsiveness.MethodsSecondary analysis of a prospective observational study from April 2016 to December 2017 in two French teaching hospitals. We included critically ill patients who were monitored by esophageal Doppler monitoring and an invasive arterial line, and received a 250-500 mL crystalloid fluid challenge. The main outcome measure was the predictive score discrimination evaluated by the area under the receiver operating characteristics curve.ResultsThe three baseline PRAM-derived parameters associated with fluid responsiveness in univariate analysis were pulse pressure variation, cardiac cycle efficiency, and arterial elastance (P

Abstract Background Hemodynamic instability is a frequent complication of continuous renal replacement therapy (CRRT). Postural tests (i.e., passive leg raising in the supine position or Trendelenburg maneuver in the prone position) combined with measurement of cardiac output are highly reliable to identify preload-dependence and may provide new insights into the mechanisms involved in hemodynamic instability related to CRRT (HIRRT). We aimed to assess the prevalence and risk factors of HIRRT associated with preload-dependence in ICU patients. We conducted a single-center prospective observational cohort study in ICU patients with acute kidney injury KDIGO 3, started on CRRT in the last 24 h, and monitored with a PiCCO® device. The primary endpoint was the rate of HIRRT episodes associated with preload-dependence during the first 7 days after inclusion. HIRRT was defined as the occurrence of a mean arterial pressure below 65 mmHg requiring therapeutic intervention. Preload-dependence was assessed by postural tests every 4 h, and during each HIRRT episode. Data are expressed in median [1st quartile–3rd quartile], unless stated otherwise. Results 42 patients (62% male, age 69 [59–77] year, SAPS-2 65 [49–76]) were included 6 [1–16] h after CRRT initiation and studied continuously for 121 [60–147] h. A median of 5 [3–8] HIRRT episodes occurred per patient, for a pooled total of 243 episodes. 131 episodes (54% [CI95% 48–60%]) were associated with preload-dependence, 108 (44%, [CI95% 38–51%]) without preload-dependence, and 4 were unclassified. Multivariate analysis (using variables collected prior to HIRRT) identified the following variables as risk factors for the occurrence of HIRRT associated with preload-dependence: preload-dependence before HIRRT [odds ratio (OR) = 3.82, p 8 h (OR = 0.56, p

The pulmonary artery catheter (PAC) is considered the gold standard for cardiac index monitoring. Recently new and less invasive methods to assess cardiac performance have been developed. The aim of our study was to assess the reliability of a non-invasive monitor utilizing bioreactance (Starling SV) and a non-calibrated mini-invasive pulse contour device (FloTrac/EV1000, fourth-generation software) compared to bolus thermodilution technique with PAC (TDCO) during off-pump coronary artery bypass surgery (OPCAB). In this prospective study, 579 simultaneous intra- and postoperative cardiac index measurements obtained with Starling SV, FloTrac/EV1000 and TDCO were compared in 20 patients undergoing OPCAB. The agreement of data was investigated by Bland–Altman plots, while trending ability was assessed by four-quadrant plots with error grids. In comparison with TDCO, Starling SV was associated with a bias of 0.13 L min−1 m−2 (95% confidence interval, 95% CI, 0.07 to 0.18), wide limits of agreement (LOA, − 1.23 to 1.51 L min−1 m−2), a percentage error (PE) of 60.7%, and poor trending ability. In comparison with TDCO, FloTrac was associated with a bias of 0.01 L min−1 m−2 (95% CI − 0.05 to 0.06), wide LOA (− 1.27 to 1.29 L min−1 m−2), a PE of 56.8% and poor trending ability. Both Starling SV and fourth-generation FloTrac showed acceptable mean bias but imprecision due to wide LOA and high PE, and poor trending ability. These findings indicate limited reliability in monitoring cardiac index in patients undergoing OPCAB. [ABSTRACT FROM AUTHOR]

BackgroundEvaluation of fluid responsiveness in intensive care unit (ICU) patients is crucial. This study was to determine whether changes in the cardiac index (CI) induced by a unilateral passive leg raising (PLR) test in spontaneously breathing patients can estimate fluid responsiveness.MethodsThis was a prospective study, and 40 patients with spontaneous breathing activity who were considered for volume expansion (VE) were included. CI data were obtained in a semirecumbent position, during unilateral PLR, bilateral PLR, and immediately after VE. If the CI increased more than 15% in response to the expansion in volume, patients were defined as responders.ResultsThe results showed that a unilateral PLR-triggered CI increment of ≥7.5% forecasted a fluid-triggered CI increment of ≥15% with 77.3% sensitivity and 83.3% specificity with and an area under the receiver operating characteristic (ROC) curve of 0.82 [P < 0.001]. Compared with that for bilateral PLR, the area under the ROC curve constructed for unilateral PLR-triggered changes in CI (ΔCI) was not significantly different (p = 0.1544).ConclusionΔCI >7.5% induced by unilateral PLR may be able to predict fluid responsiveness in spontaneously breathing patients and is not inferior to that induced by bilateral PLR.Trial RegistrationUnilateral passive leg raising test to assess patient volume responsiveness: Single-Center Clinical Study, ChiCTR2100046762. Registered May 28, 2021.

Abstract Background Many maneuvers assessing fluid responsiveness (minifluid challenge, lung recruitment maneuver, end-expiratory occlusion test, passive leg raising) are considered as positive when small variations in cardiac index, stroke volume index, stroke volume variation or pulse pressure variation occur. Pulse contour analysis allows continuous and real-time cardiac index, stroke volume, stroke volume variation and pulse pressure variation estimations. To use these maneuvers with pulse contour analysis, the knowledge of the minimal change that needs to be measured by a device to recognize a real change (least significant change) has to be studied. The aim of this study was to evaluate the least significant change of cardiac index, stroke volume index, stroke volume variation and pulse pressure variation obtained using pulse contour analysis (ProAQT®, Pulsion Medical System, Germany). Methods In this observational study, we included 50 mechanically ventilated patients undergoing neurosurgery in the operating room. Cardiac index, stroke volume index, pulse pressure variation and stroke volume variation obtained using ProAQT® (Pulsion Medical System, Germany) were recorded every 12 s during 15-min steady-state periods. Least significant changes were calculated every minute. Results Least significant changes statistically differed over time for cardiac index, stroke volume index, pulse pressure variation and stroke volume variation (p

Background: Hemodynamic instability is a frequent complication of continuous renal replacement therapy (CRRT). Postural tests (i.e., passive leg raising in the supine position or Trendelenburg maneuver in the prone position) combined with measurement of cardiac output are highly reliable to identify preload-dependence and may provide new insights into the mechanisms involved in hemodynamic instability related to CRRT (HIRRT). We aimed to assess the prevalence and risk factors of HIRRT associated with preload-dependence in ICU patients. We conducted a single-center prospective observational cohort study in ICU patients with acute kidney injury KDIGO 3, started on CRRT in the last 24 h, and monitored with a PiCCO® device. The primary endpoint was the rate of HIRRT episodes associated with preload-dependence during the first 7 days after inclusion. HIRRT was defined as the occurrence of a mean arterial pressure below 65 mmHg requiring therapeutic intervention. Preload-dependence was assessed by postural tests every 4 h, and during each HIRRT episode. Data are expressed in median [1st quartile–3rd quartile], unless stated otherwise. Results: 42 patients (62% male, age 69 [59–77] year, SAPS-2 65 [49–76]) were included 6 [1–16] h after CRRT initiation and studied continuously for 121 [60–147] h. A median of 5 [3–8] HIRRT episodes occurred per patient, for a pooled total of 243 episodes. 131 episodes (54% [CI95% 48–60%]) were associated with preload-dependence, 108 (44%, [CI95% 38–51%]) without preload-dependence, and 4 were unclassified. Multivariate analysis (using variables collected prior to HIRRT) identified the following variables as risk factors for the occurrence of HIRRT associated with preload-dependence: preload-dependence before HIRRT [odds ratio (OR) = 3.82, p < 0.001], delay since last HIRRT episode > 8 h (OR = 0.56, p < 0.05), lactate (OR = 1.21 per 1-mmol L−1 increase, p < 0.05), cardiac index (OR = 0.47 per 1-L min−1 m−2 increase, p < 0.001) and SOFA at ICU admission (OR = 0.91 per 1-point increase, p < 0.001). None of the CRRT settings was identified as risk factor for HIRRT. Conclusions: In this single-center study, HIRRT associated with preload-dependence was slightly more frequent than HIRRT without preload-dependence in ICU patients undergoing CRRT. Testing for preload-dependence could help avoiding unnecessary decrease of fluid removal in preload-independent HIRRT during CRRT. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the accuracy of non-calibrated multi-beat analysis continuous cardiac output (CCO MBA ), against calibrated pulse-contour analysis continuous cardiac output (CCO PCA ) during a passive leg raise (PLR) and/or a fluid challenge (FC)., Design: Observational, single-centre, prospective study., Setting: Tertiary academic medical intensive care unit, Lyon, France., Participants: Adult patients receiving norepinephrine, monitored by CCO PCA , and in which a PLR and/or a FC was indicated., Main Outcome Measures: CCO MBA and CCO PCA were recorded prior to and during the PLR/FC to evaluate bias and evaluate changes in CCO MBA and CCO PCA (∆%CCO MBA and ∆%CCO PCA ). Fluid responsiveness was identified by an increase >15% in calibrated cardiac output after FC, to identify the optimal ∆%CCO MBA threshold during PLR to predict fluid responsiveness., Results: 29 patients (median age 68 [IQR: 57-74]) performed 28 PLR and 16 FC. The bias between methods increased with higher CCO PCA values, with a percentage error of 64% ( 95% confidence interval: 52%-77%). ∆%CCO MBA adequately tracked changes in ∆%CCO PCA with an angular bias of 2 ± 29°. ∆%CCO MBA during PLR had an AUROC of 0.92 ( P < 0.05), with an optimal threshold >14% to predict fluid responsiveness (sensitivity: 0.99, specificity: 0.87)., Conclusions: CCO MBA showed a non-constant bias and a percentage error >30% against calibrated CCO PCA , but an adequate ability to track changes in CCO PCA and to predict fluid responsiveness., (© 2024 The Authors.)

Abstract Background Haemodynamic variations normally occur in anaesthetized animals, in relation to the animal status, administered drugs, sympathetic and parasympathetic tone, fluid therapy and surgical stimulus. The possibility to measure some cardiovascular parameters, such as cardiac output (CO), during anaesthesia would be beneficial for both the anaesthesia management and its outcome. New techniques for the monitoring of CO are aimed at finding methods which are non invasive, accurate and with good trending ability, which can be used in a clinical setting. The aim of this study was to compare the Pressure Recording Analytical Method (PRAM) with the pulmonary artery thermodilution (TD) for the measurement of cardiac output in 6 anaesthetized critically ill dogs. Results Fifty-four pairs of CO measurements were obtained with a median (range) of 3.33 L/min (0.81–7.21) for PRAM-CO and 3.48 L/min (1.41–6.56) for TD-CO. The Bland-Altman analysis showed a mean bias of 0.17 L/min with limits of agreement (LoA) of − 0.46 to 0.81 L/min. The percentage error resulted 18.2%. The 4-quadrant plot analysis showed an acceptable concordance (93%) between the 2 methods. The polar plot showed a good trending ability with the mean angular bias of 3.9° and radial LoA ± 12.1°. Conclusions The PRAM resulted in good precision, acceptable concordance and good trending ability for the measure of CO in the anaesthetized dog, representing a promising alternative to thermodilution for the measurement of CO. Among all the pulse contour methods available on the market it is the only one that does not require any calibration or adjustment of the measurement. Further studies are required to verify the ability of this method to accurately measure cardiac output even during unstable hemodynamic conditions.

Telemonitoring systems equipped with photoplethysmography-based contour analysis of the digital arterial volume pulse (DVP) can be optimal tools for remote monitoring of cardiovascular patients; however, the method is known to be sensitive to errors. We aimed to show that DVP analysis is a reliable method to track cardiovascular status. We used our proprietary SCN4ALL telemedicine system and analyzed nine parameters derived from the DVP and its second derivative (SDDVP). First, we assessed the repeatability of system measurements by detecting artificial signals. Then test–retest reliability of human measurements was evaluated in healthy individuals under standardized conditions. The SCN4ALL system analyzed each parameter with high accuracy (coefficients of variation (CVs) < 1%). Test–retest reliability of most parameters (stiffness index, reflection index, left ventricular ejection time index, b/a, heart rate) was satisfactory (CVs < 10%) in healthy individuals. However, aging index and d/a ratio derived from the SDDVP were more variable. Photoplethysmography-based pulse contour analysis is a reliable method to monitor cardiovascular status if measurements are performed with a system of high accuracy. Our results highlighted that SDDVP parameters can be interpreted with limitations due to (patho)physiological variations of the DVP. We recommend the evaluation of these parameters only in measurements where all inflections of SDDVP are detected reliably. [ABSTRACT FROM AUTHOR]

Evaluation of a new Windkessel model based pulse contour method (WKflow) to calculate stroke volume in patients undergoing intra-aortic balloon pumping (IABP). Preload changes were induced by vena cava occlusions (VCO) in twelve patients undergoing cardiac surgery to vary stroke volume (SV), which was measured by left ventricular conductance volume method (SVlv) and WKflow (SVwf). Twelve VCO series were carried out during IABP assist at a 1:2 ratio and seven VCO series were performed with IABP switched off. Additionally, SVwf was evaluated during nine episodes of severe arrhythmia. VCO's produced marked changes in SV over 10-20 beats. 198 paired data sets of SVlv and SVwf were obtained. Bland-Altman analysis for the difference between SVlv and SVwf during IABP in 1:2 mode showed a bias (accuracy) of 1.04 ± 3.99 ml, precision 10.9% and limits of agreement (LOA) of - 6.94 to 9.02 ml. Without IABP bias was 0.48 ± 4.36 ml, precision 11.6% and LOA of - 8.24 to 9.20 ml. After one thermodilution calibration of SVwf per patient, during IABP the accuracy improved to 0.14 ± 3.07 ml, precision to 8.3% and LOA to - 6.00 to + 6.28 ml. Without IABP the accuracy improved to 0.01 ± 2.71 ml, precision to 7.5% and LOA to - 5.41 to + 5.43 ml. Changes in SVlv and SVwf were directionally concordant in response to VCO's and during severe arrhythmia. (R2 = 0.868). The SVwf and SVlv methods are interchangeable with respect to measuring absolute stroke volume as well as tracking changes in stroke volume. The precision of the non-calibrated WKflow method is about 10% which improved to 7.5% after one calibration per patient. [ABSTRACT FROM AUTHOR]

Telemonitoring systems equipped with photoplethysmography-based contour analysis of the digital arterial volume pulse (DVP) can be optimal tools for remote monitoring of cardiovascular patients; however, the method is known to be sensitive to errors. We aimed to show that DVP analysis is a reliable method to track cardiovascular status. We used our proprietary SCN4ALL telemedicine system and analyzed nine parameters derived from the DVP and its second derivative (SDDVP). First, we assessed the repeatability of system measurements by detecting artificial signals. Then test–retest reliability of human measurements was evaluated in healthy individuals under standardized conditions. The SCN4ALL system analyzed each parameter with high accuracy (coefficients of variation (CVs) < 1%). Test–retest reliability of most parameters (stiffness index, reflection index, left ventricular ejection time index, b/a, heart rate) was satisfactory (CVs < 10%) in healthy individuals. However, aging index and d/a ratio derived from the SDDVP were more variable. Photoplethysmography-based pulse contour analysis is a reliable method to monitor cardiovascular status if measurements are performed with a system of high accuracy. Our results highlighted that SDDVP parameters can be interpreted with limitations due to (patho)physiological variations of the DVP. We recommend the evaluation of these parameters only in measurements where all inflections of SDDVP are detected reliably.

The non-invasive Nexfin cardiac output (CO) monitor shows a low level of agreement with the gold standard thermodilution method in morbidly obese patients. Here we investigate whether this disagreement is related to excessive bodyweight, and can be improved when bodyweight derivatives are used instead. We performed offline analyses of cardiac output recordings of patient data previously used and partly published in an earlier study by our group. In 30 morbidly obese patients (BMI > 35 kg/m2) undergoing laparoscopic gastric bypass, cardiac output was simultaneously determined with PiCCO thermodilution and Nexfin pulse-contour method. We investigated if agreement of Nexfin-derived CO with thermodilution CO improved when ideal and adjusted-instead of actual- bodyweight were used as input to the Nexfin. Bodyweight correlated with the difference between Nexfin-derived and thermodilution-derived CO (r = -0.56; p = 0.001). Bland Altman analysis of agreement between Nexfin and thermodilution-derived CO revealed a bias of 0.4 ± 1.6 with limits of agreement (LOA) from -2.6 to 3.5 L min when actual bodyweight was used. Bias was -0.6 ± 1.4 and LOA ranged from -3.4 to 2.3 L min when ideal bodyweight was used. With adjusted bodyweight, bias improved to 0.04 ± 1.4 with LOA from -2.8 to 2.9 L min. Our study shows that agreement of the Nexfin-derived with invasive CO measurements in morbidly obese patients is influenced by body weight, suggesting that Nexfin CO measurements in patients with a BMI above 35 kg/m2 should be interpreted with caution. Using adjusted body weight in the Nexfin CO-trek algorithm reduced the bias. [ABSTRACT FROM AUTHOR]

The question of environmentally sustainable perioperative medicine represents a new challenge in an era of cost constraints and climate crisis. The French Society of Anaesthesia and Intensive Care (SFAR) recommends stroke volume optimization in high-risk surgical patients. Pulse contour techniques have become increasingly popular for stroke volume monitoring during surgery. Some require the use of specific disposable pressure transducers (DPTs), whereas others can be used with standard DPTs. Quantify and compare the carbon footprint and cost of pulse contour techniques using specific and standard DPTs on a yearly basis and at a national level. We estimated the number of high-risk surgical patients monitored every year in France with a pulse contour technique, and the plastic waste, carbon footprint and cost associated with the use of specific and standard DPTs. When compared to pulse contour techniques working with a standard DPT, techniques requiring a specific DPT are responsible for an increase in carbon dioxide emission estimated at 65–83 tons/yr and for additional hospital cost estimated at €67 million/yr. If, as recommended by the SFAR, all high-risk surgical patients were monitored, the difference would reach 179–227 tons/yr for the environmental impact and €187 million/yr for the economic impact. From an environmental and economic standpoint, pulse contour techniques working with standard DPTs should be recommended for the perioperative hemodynamic monitoring of high-risk surgical patients. [ABSTRACT FROM AUTHOR]

Goal: The goal of this study is to present a modified pulse contour method to estimate the stroke volume (SV) based on an oscillometric sphygmomanometer. Methods: The pulse contour was extracted from the pulse signal of the cuff pressure. The characteristics of the brachial artery, as well as the compliance ( $C_{{\rm artery}}) and time constant \tauof the Windkessel model, could be determined and used to estimate the SV once the apparatus finished the blood pressure measurement. Results: Assessments of the SV by echocardiography and our method were carried out in 55 subjects. The change in the brachial arterial volume obtained by our method was significantly correlated with that of the two-dimensional ultrasound method (r_{v} = 0.871 ). The estimated SV values by our method for male and female groups, {\rm SV_{estimate}}, were also significantly correlated with the echocardiography results, SVref ( rmale = 0.680, $r_{{\rm female}} = 0.706 ). The Bland–Altman plot showed agreement between SVref and SVestimate , with all data points contained within the limits of agreement (± 2 SD). The mean difference and standard deviation (mean ± SD) were 0.101 ± 14.880 ml and 0.650 ± 11.990 ml for the male and female groups, respectively. Conclusion: The blood pressure, SV, and cardiac output were measured simultaneously, making our method well suited for home use. Significance: Our method was embedded in an oscillometric sphygmomanometer. [ABSTRACT FROM AUTHOR]

Abstract: Optimization of fluid status, perfusion pressure and cardiac output in intraoperative and critical care settings improves clinical outcomes. Cardiac output is a measure of the blood pumped around the circulation. Modelling of the circulation facilitates estimation of cardiac output from readily measured variables. Methods include thermodilution, analysis of arterial pressure waveforms, Doppler measurements of blood flow velocity, electrical bioimpedance and regional oxygenation. Physical limitations of each measurement technique produce predictable as well as unquantifiable errors, leading to over- or underestimates of cardiac output. [Copyright &y& Elsevier]

Abstract: Background: The cardiac output (CO) is classically measured in intensive care unit patients. pulse contour (PC) method allows monitoring of CO. Objective: The aim of the present study was to assess the ability of PC to assess the fluid responsiveness defined as an increase in CO more than or equal to 15% after 500mL hydroxyethyl starch over 20minutes. Patients and methods: In this observational prospective study, patients in shock in whom a PC method was inserted were included. CO was measure using the PC and thermodilution methods before and after a fluid challenge indicated by the physician. The correlation coefficient was measured, the diagram of Bland and Altman was built and the percentage of error (Critchley and Critchley method) was calculated. The ability of PC to diagnose fluid responsiveness was assessed using a receiver operating characteristics (ROC) curve. Results: Sixty-two fluid challenges were performed in 37 included patients. After fluid challenge, r2 was 0.05 (P <0.01), the bias between PC and thermodilution was 0.3±1.2L/min and the percentage of error was 36%. The area of the ROC curve was 0.601 [0.468–0.723]. Conclusion: In ICU patients with shock, PC cannot replace thermodilution to diagnose fluid responsiveness. [Copyright &y& Elsevier]

Cardiac output measurement from arterial pressure waveforms presumes a defined relationship between the arterial pulse pressure (PP), vascular compliance (C), and resistance (R). Cardiac output estimates degrade if these assumptions are incorrect. We hypothesized that sepsis would differentially alter central and peripheral vasomotor tone, decoupling the usual pressure wave propagation from central to peripheral sites. We assessed arterial input impedance (Z), C, and R from central and peripheral arterial pressures, and aortic blood flow in an anesthetized porcine model (n = 19) of fluid resuscitated endotoxic shock induced by endotoxin infusion (7 µg⋅kg-1⋅-1 increased to 14 and 20 µg⋅kg-1⋅h-1 every 10 min and stopped when mean arterial pressure <40 mmHg or SvO2, < 45%). Aortic, femoral, and radial artery pressures and aortic and radial artery flows were measured. Z was calculated by FFT of flow and pressure data. R and C were derived using a two-element Windkessel model. Arterial PP increased from aortic to femoral and radial sites. During stable endotoxemia with fluid resuscitation, aortic and radial blood flows returned to or exceeded baseline while mean arterial pressure remained similarly decreased at all three sites. However, aortic PP exceeded both femoral and radial arterial PP. Although Z, R, and C derived from aortic and radial pressure and aortic flow were similar during baseline, Z increases and C decreases when derived from aortic pressure whereas Z decreases and C increases when derived from radial pressure, while R decreased similarly with both pressure signals. This central-to-peripheral vascular tone decoupling, as quantified by the difference in calculated Z and C from aortic and radial artery pressure, may explain the decreasing precision of peripheral arterial pressure profile algorithms in assessing cardiac output in septic shock patients and suggests that different algorithms taking this vascular decoupling into account may be necessary to improve their precision in this patient population. [ABSTRACT FROM AUTHOR]

Background: Both occult hypoperfusion and volume overload are associated with increased morbidity and mortality in critically ill patients. Accurately predicting fluid responsiveness (FRes) allows for optimization of cardiac performance while avoiding fluid overload and prolonged mechanical ventilation. Objective: To simultaneously assess the ability to predict FRes using the stroke volume variation (SVV) obtained with the Vigileo/Flotrac monitor and inferior vena cava respiratory variation (ΔIVC) measured by standard echocardiography ([ECHO) during mechanical ventilation. Methods: We included medical intensive care unit (ICU) patients undergoing mechanical ventilation that required vasopressors, had worsening organ function, and that were well adapted to the ventilator. We excluded patients requiring escalating doses of vasopressors, hemodialysis, with ascites and patients with atrial fibrillation or a heart rate >120/min. Stroke volume index (SVI) and SVV were obtained from the Vigileo monitor whereas ΔIVC was obtained with ECHO (M-mode). Doppler ECHO was used to measure SVI and used to determine FRes (defined by SVI increase ≥10%). A data set was obtained before and 30 minutes after a 10-minute fluid challenge (FC) with 500 mL of saline. Results: In all, 25 patients were prospectively enrolled over an 8-month period. A total of 12 patients had acute respiratory distress syndrome (ARDS), 3 had a cardiac arrest, and 10 had sepsis. The patients’ mean age was 61.36 years (±13.7), study enrollment since ICU admission was 3.4 days (±3.39), the Sequential Organ Failure Assessment (SOFA) score was 12.44 (±2.59), and the tidal volume 8.6 mL/kg (±1.68). Of the 25 patients, 8 (32%) were FRes. The correlation coefficient between the baseline ΔIVC and percentage increase in SVI (by ECHO) after an FC was R2 = .51 with a receiver operating characteristic (ROC) curve of 0.81 while that for the baseline SVV by Vigileo was R2 = .12 with an ROC curve of 0.57. The mean SVI bias between ECHO and Vigileo was -2 mL/m2, the precision was -18 to 14 and the mean error was 46%. Conclusions: ECHO assessment of the IVC variation during mechanical ventilation may prove to be a useful technique to predict FRes and guide fluid resuscitation in the ICU. The SVV obtained with the Vigileo monitor failed to predict FRes likely due to lack of calibration and the use of a complex algorithm that may be unreliable in patients with sepsis. [ABSTRACT FROM PUBLISHER]

Purpose: A pulsus parvus et tardus of the carotid artery, i.e., a small weak pulse with a delayed systolic peak, is a well-recognized clinical finding of aortic stenosis (AS). However, the diagnostic value of radial arterial pressure curves has not been specifically investigated. In this study, we investigated whether the radial arterial curves of patients with AS had distinguishable characteristics. Methods: We studied 17 AS patients (valve area less than 0.8 cm) and 17 control patients. The durations for the following intervals were measured, from the ECG-R to the beginning of the arterial pressure wave upstroke (PTT), from the ECG-R to the peak of the arterial pressure (PTT), and the difference between PTT and PTT (T). Results: The radial arterial pulse pressures did not differ significantly, indicating absence of a pulsus paruvus in the radial pressure of the AS patients. The PTT and PTT in the AS patients were 134 ± 18 and 337 ± 44 ms, respectively, while these values in the control patients were 143 ± 21 and 286 ± 64 ms. As a result of the differences in PTT and PTT, the T in the AS patients was greater than that in the control patients. The T cutoff point that gave the maximal sensitivity (0.93) and specificity (0.65) was 156 ms. Conclusion: Our study using the radial arterial curve validated a pulsus tardus as a diagnostic sign for severe AS, while the validity of a pulsus parvus as a diagnostic sign was not confirmed. [ABSTRACT FROM AUTHOR]

The article develops a testing data set comprising a large number of radial arterial blood pressure (ABP) waveform segments and contemporaneous reference cardiac output by thermodilution measurements, collected in an intensive care unit (ICU) patient population during routine clinical operations. According to the authors, data set is used to analyze a set of investigational algorithms and to establish a public resource for the comparison of alternative CO-from-ABP algorithms.

Objectives: To investigate whether measuring cardiac output and its course after cardiac surgery by a new analysis technique of radial artery pressure waves, without need for calibration (FloTrac/Vigileo [FV]; Edwards Lifesciences, Irvine, CA), conforms to the standard bolus thermodilution method via a pulmonary artery catheter (PAC). Design: Prospective study. Setting: Intensive care unit of university hospital. Participants: Twenty patients for up to 24 hours after cardiac surgery. Interventions: Simultaneous and triplicate PAC thermodilution and FV cardiac output measurements at 1 and 3 hours after surgery and the following morning. Measurements and Main Results: Fifty-six simultaneous measurement sets were obtained. Mean cardiac output (PAC) ranged between 2.8 and 10.3 L/min and for the FV method between 3.3 and 8.8 L/min. The coefficient of variation for pooled measurements was 7.3% for the PAC and 3.0% for the FV method. For pooled data, the r 2 was 0.55 (p < 0.001), with a bias of −0.14, precision of 1.00 L/min, and 95% limits of agreement between −2.14 and 1.87 L/min in a Bland-Altman plot. Also, the FV method tended to overestimate cardiac output when <7 L/min and increased with time, whereas mean arterial pressure increased and PAC cardiac output did not change. Changes in cardiac output correlated (r 2 = 0.52, p < 0.001). Conclusions: The FV arterial pressure waveform analysis method is a clinically applicable method for cardiac output assessment without calibration, after cardiac surgery. It performs well at low cardiac outputs but remains sensitive to changes in vascular tone. [Copyright &y& Elsevier]

Objective: A less-invasive method has been developed that may provide an alternative to monitor cardiac output from arterial pressure: beat-to-beat values of cardiac output can be obtained by pressure recording analytical method (PRAM). The purpose of this study was to assess the reliability of cardiac output determination by PRAM in cardiac surgery. Methods: Cardiac output was measured in 28 patients undergoing coronary artery bypass grafting at 15 min after anaesthesia induction, 30 min after extracorporeal circulation, 1 and 3 h after arrival in the intensive care unit using thermodilution (ThD) method through a pulmonary artery catheter and PRAM. ThD cardiac output was calculated as the mean of five separate measurements. PRAM provided beat-by-beat cardiac output data continuously throughout the study and the cardiac output values displayed on a dedicated personal computer at each time point were recorded. Correlations were calculated and differences were compared by Bland–Altman analysis. Results: A total of 112 measurements were obtained. Cardiac output ranged from 2.3 to 7.4 l/min, and a good linear correlation (R2=0.78, P<0.0001) was found between ThD and PRAM. The highest degree of correlation (R2=0.86) was obtained at 3 h after arrival in the intensive care unit. The lower degree of correlation (R2=0.70) was obtained 30 min after extracorporeal circulation. At Bland–Altman analysis, the overall estimates of cardiac output measured by PRAM closely agreed with ThD (mean difference, 0.027; standard deviation, 0.43; limits of agreement, -0.83 and +0.89). Conclusions: Under the studied conditions, our results demonstrate good agreement between PRAM data and ThD measurements, and this new method has shown to be accurate for real-time monitoring of cardiac output in cardiac surgery. Further studies will be required to assess this method in higher-risk patients and in the setting of haemodynamic instability or arrhythmias. This is the first study designed to assess the accuracy of PRAM in cardiac surgery. [Copyright &y& Elsevier]

The aim of this study was to compare beat-to-beat changes in stroke volume (SV) estimated by two different pressure wave analysis techniques during orthostatic stress testing: pulse contour analysis and Modelflow, ie, simulation of a three-element model of aortic input impedance. A reduction in SV was introduced in eight healthy young men (mean age, 25; range, 19–32 y) by a 30-minute head-up tilt maneuver. Intrabrachial and noninvasive finger pressure were monitored simultaneously. Beat-to-beat changes in SV were estimated from intrabrachial pressure by pulse contour analysis and Modelflow. In addition, the relative differences in Modelflow SV obtained from intrabrachial pressure and noninvasive finger pressure were assessed. Beat-to-beat changes in Modelflow SV from intrabrachial pressure were comparable with pluse contour measures. The relative difference between the two methods amounted to 0.1±1% (mean±SEM) and was not dependent on the duration of tilt. The diference between Modelflow apoplied to intrabrachial pressure and finger pressure amounted to −2.7±1.3% (p=0.04). This difference was not dependent on the duration of tilt or level of arterial pressure. Based on different mathematical models of the human arterial system, pulse contour and Modelflow compute similar changes in SV from intrabrachial pressure during orthostatic stress testing in young healthy men. The magnitude of the differnece in SV derived from intrabrachial and finger pressure may vary among subjects; Modelflow SV from noninvasive finger pressure tracks fast and brisk changes in SV derived from intrabrachial pressure. [ABSTRACT FROM AUTHOR]

The coronary arteries are a system of elastic tubes with one end open to the aorta and with a high resistance at the other end. The basic pattern of coronary input flow is determined 1. by the primary inflow wave due to the aortic pressure pulsation and 2. by a secondary wave which is generated by the periodic obstruction of outflow at the peripheral resistance due to the contraction of the heart. By means of the simplified model of a homogeneous elastic tube, details and oscillations of the coronary flow pattern could be explained as due to reflection and superposition of these primary and secondary waves. Flowpatterns constructed by use of this model were compared with flow pulses recorded in anesthetized dogs in the left circumflex coronary artery with an electromagnetic flowmeter. A characteristic feature of the apparent input impedance of a coronary artery has been found experimentally and could be explained by the fact, that the myocardial contraction serves as an additional energy source within the coronary system. The possible usefulness and physiological importance of the application of analytical methods to the hemodynamics of the coronary arteries is discussed. [ABSTRACT FROM AUTHOR]