Uncalibrated Pulse Contour Method Research Articles

Cardiac output monitoring with uncalibrated pulse contour method (PROAQT/PULSIOFLEX®) after major cardiac surgery

IntroductionThe ProAQT/Pulsioflex® (PF) is an arterial pressure–derived continuous cardiac output monitoring technique. This study aimed to evaluate the PF after major cardiac surgery.MethodsThis was an ancillary study of the SUCCES study (clinical trial number: 02782520), a prospective randomized study whose purpose was to compare the hemodynamic effect of a fluid challenge with hypertonic saline or lactated Ringer's®. Inclusion criteria were patients requiring a Swan-Ganz catheter (SGc) for cardiac surgery and requiring fluid challenge during the postoperative period. Cardiac index (CI) was monitored simultaneously in patients by the PF or by an SGc continuous thermodilution. Statistical analysis was performed using linear regression and Bland-Altman analysis. Intermethod agreement during volume expansion was assessed using the Kappa statistic.ResultsThe data of 22 patients were reviewed. We analyzed 12,734 pairs of measurements. CI values were slightly but significantly different between the SGc system (2.52 ± 0.52, 95% confidence interval of the mean: 2.51-2.53 L/min/m2) and the PF (2.58 ± 0.72, 95% confidence interval of the mean: 2.57-2.59 L/min/m2), p < 0.001. The correlation coefficient was R = 0.86 (95% confidence interval = 0.84 to 0.88, p <0.001), the bias was –0.06 L/min, and limits of agreement were –1.18 to 1.05 L/min, with a percentage of error of 44%. Response to volume expansion was considered as positive for 12 (75%) cases in the SGc group and for 2 (12%) cases in the PF group (weighted Kappa –0.09; 95% confidence interval = –0.35 to 0.17).DiscussionThe concordance between PF and SGc is moderate after cardiac surgery. The PF did not correctly track changes in CI during fluid expansion. The ProAQT/Pulsioflex® (PF) is an arterial pressure–derived continuous cardiac output monitoring technique. This study aimed to evaluate the PF after major cardiac surgery. This was an ancillary study of the SUCCES study (clinical trial number: 02782520), a prospective randomized study whose purpose was to compare the hemodynamic effect of a fluid challenge with hypertonic saline or lactated Ringer's®. Inclusion criteria were patients requiring a Swan-Ganz catheter (SGc) for cardiac surgery and requiring fluid challenge during the postoperative period. Cardiac index (CI) was monitored simultaneously in patients by the PF or by an SGc continuous thermodilution. Statistical analysis was performed using linear regression and Bland-Altman analysis. Intermethod agreement during volume expansion was assessed using the Kappa statistic. The data of 22 patients were reviewed. We analyzed 12,734 pairs of measurements. CI values were slightly but significantly different between the SGc system (2.52 ± 0.52, 95% confidence interval of the mean: 2.51-2.53 L/min/m2) and the PF (2.58 ± 0.72, 95% confidence interval of the mean: 2.57-2.59 L/min/m2), p < 0.001. The correlation coefficient was R = 0.86 (95% confidence interval = 0.84 to 0.88, p <0.001), the bias was –0.06 L/min, and limits of agreement were –1.18 to 1.05 L/min, with a percentage of error of 44%. Response to volume expansion was considered as positive for 12 (75%) cases in the SGc group and for 2 (12%) cases in the PF group (weighted Kappa –0.09; 95% confidence interval = –0.35 to 0.17). The concordance between PF and SGc is moderate after cardiac surgery. The PF did not correctly track changes in CI during fluid expansion.

Comparison of estimation of cardiac output using an uncalibrated pulse contour method and echocardiography during veno-venous extracorporeal membrane oxygenation.

During veno-venous extracorporeal membrane oxygenation, cardiac output monitoring is essential to assess tissue oxygen delivery. Adequate arterial oxygenation depends on the ratio between the extracorporeal pump blood flow and the cardiac output. The aim of this study was to compare estimates of cardiac output and blood flow/cardiac output ratios made using an uncalibrated pulse contour method with those made using echocardiography in patients treated with veno-venous extracorporeal membrane oxygenation. Cardiac output was estimated simultaneously using a pulse contour method (MostCareUp; Vygon, Encouen, France) and echocardiography in 17 hemodynamically stable patients treated with veno-venous extracorporeal membrane oxygenation. Comparisons were made using Bland-Altman and linear regression analysis. There were significant correlations between cardiac output estimated using pulse contour method and echocardiography and between blood flow/cardiac output estimated using pulse contour method and blood flow/cardiac output estimated using echocardiography (r = 0.84, p < 0.001 and r = 0.87, p < 0.001, respectively). Bland-Altman analysis showed a good agreement (bias -0.20 ± 0.50 L/min) and a low percentage of error (25%) for the cardiac output values estimated by the two methods. The bias between the blood flow/cardiac output ratios obtained with the two methods was 5.19% ± 12.3% (percentage of error = 28.1%). The pulse contour method is a valuable alternative to echocardiography for the assessment of cardiac output and the blood flow/cardiac output ratio in patients treated with veno-venous extracorporeal membrane oxygenation.

Validation of radial artery-based uncalibrated pulse contour method (PulsioFlex) in critically ill patients: A observational study.

Because of their simplicity, uncalibrated pulse contour (UPC) methods have been introduced into clinical practice in critical care but are often validated with a femoral arterial waveform. We aimed to test the accuracy of cardiac index (CI) measurements and trending ability from a radial artery with one UPC. An observational study. Tertiary care mixed-surgical ICU. Data were obtained from April 2015 to July 2016. We studied 20 critically ill mechanically ventilated patients monitored by UPC (PulsioFlex; Pulsion Medical Systems SE, Feldkirchen, Germany). We used transpulmonary thermodilution (PiCCO2) as a reference. Bland-Altman-analyses with percentage errors were calculated to assess the accuracy of CI values from radial pulse contour analysis (CIRAD), autocalibration (CIAC) and femoral pulse contour analysis (CIFEM). All were compared with a reference (CITD) at 4-h intervals for 24 h. Trending ability was assessed by polar-plots and four-quadrant-plots. CI is given in l min m. Bland-Altman-analyses: for CIRAD, the mean bias was -0.1 with limits of agreement (LOA) of -2.9 to 2.7 and a percentage error of 70%; for CIAC, the mean bias was 0 with LOA -2.8 to 2.7 and a percentage error of 70%; for CIFEM, the mean bias was 0 with LOA -1.2 to 1.2 and a percentage error of 30%, respectively. Polar plots for trending: for CIRAD, the angular bias was 12° with radial LOA of 39°, a polar concordance rate of 73% and a concordance rate of 67% in the four-quadrant-plot; for CIAC, the angular bias was 4° with radial LOA of 41°, polar concordance rate of 79% and a concordance rate of 74% in the four quadrant plot; for CIFEM, the angular bias was -2° with radial LOA of 50°, polar concordance rate of 74% and a concordance rate of 81%. In critically ill patients, the PulsioFlex system connected to a radial arterial catheter is inaccurate for CI measurements and does not track changes in CI adequately. We therefore recommend using validated thermodilution techniques for monitoring in the critical care setting.

Measurement of cardiac output in children: comparison between direct Fick method and pressure recording analytical method: preliminary report

There are few methods of cardiac output (CO) estimation validated in children. The aim of this study is to investigate the reliability of an uncalibrated pulse contour method of CO estimation, the pressure recording analytical method (PRAM), in pediatric patients scheduled for diagnostic right and left heart catheterization, compared with the oxygen-direct Fick method.

Noninvasive Continuous Cardiac Output by the Nexfin Before and After Preload-Modifying Maneuvers

The Nexfin uses an uncalibrated pulse contour method for the continuous measurement of cardiac output (CO) in a totally noninvasive manner. Since the accuracy of pulse contour methods and their ability to track changes in CO have been repeatedly questioned, we have compared the CO measured by the Nexfin (NAPCO) with the CO measured by the pulmonary artery catheter (PACCO) in cardiosurgical patients before and after preload-modifying maneuvers. Twenty-eight patients who underwent on-pump cardiac surgery, of whom 18 were receiving vasopressor and/or inotropic therapy, were studied during the first postoperative hours. Preload modification, in the form of either a fluid challenge or a passive leg raising maneuver, was done whenever clinically indicated, with PACCO and NAPCO being simultaneously measured before and after each intervention. A fluid challenge was administered to 22 patients, and the passive leg raising maneuver was performed in 6 patients. These interventions were repeated in 19 patients producing a total of 47 pairs of measurements. At baseline, mean (±SD) CO was 4.9 ± 1.1 and 5.0 ± 1.4 L·min(-1), for the PACCO and NAPCO, respectively, bias 0.1 ± 1.0, 95% prediction interval -2.5 to 2.4 L·min(-1), and 39% of error. After preload modification, the mean CO was 5.6 ± 1.3 and 5.6± 1.5 L·min(-1) for the PACCO and NAPCO, respectively, bias -0.0 ± 1.1, 95% prediction interval -2.6 to 2.7 L·min(-1), and 38% of error. The correlation coefficients (r) between the PACCO and NAPCO before and after preload modification were 0.71 (95% confidence interval [95% CI], 0.53-0.82) and 0.70 (95% CI, 0.52-0.82), respectively. Preload modification induced similar absolute changes in PACCO and NAPCO (r = 0.9, P < 0.0001). A 4-quadrant scatter plot showed a concordance rate of 100% (95% CI, 80.5%-100%) between the changes in NAPCO and PACCO. Polar plot analysis demonstrated a small polar angle and radial limits of agreement well below the 30° benchmark. The area under a receiver operating characteristic curve, testing the ability of Nexfin to detect an increase of ≥15% in PACCO, was 0.974 (95% CI, 0.93-0.99). Although the Nexfin has limited accuracy when compared with the pulmonary artery catheter, it can reliably track preload-induced changes in CO in stable patients after cardiac surgery in the presence of moderate vasopressor and inotropic therapy. This ability, combined with its total noninvasiveness, fast installation, and ease of use, make the Nexfin a suitable monitor for the perioperative continuous measurement of CO. The reliability of this monitor in tracking the CO when significant changes in peripheral resistance take place still needs to be established.

Comparison Between an Uncalibrated Pulse Contour Method and Thermodilution Technique for Cardiac Output Estimation in Septic Patients

Background The purpose of this study was to evaluate the reliability of a new uncalibrated pulse contour method, the MostCare, in determining cardiac output (CO) in septic patients. Methods Thirty patients with septic shock admitted to an intensive care unit, receiving a norepinephrine infusion and requiring haemodynamic monitoring with a pulmonary artery catheter, were prospectively enrolled. Thermodilution measurements of CO (ThD-CO) were considered as the ‘gold standard'. MostCare was connected to the monitoring system of the radial arterial pressure waveform to obtain a continuous CO calculation (MostCare-CO). ThD-CO and MostCare-CO measurements were recorded at three different haemodynamic states: baseline (T1), after raising mean arterial pressure (MAP) to 90 mm Hg by increasing the norepinephrine infusion (T2), and after returning the MAP to baseline value by decreasing vasopressor therapy (T3). A Bland–Altman and linear regression analyses were performed. Results A total of 90 paired ThD-CO and MostCare-CO measures were obtained (range 4.1–13.9 litre min −1 for ThD-CO and 4.5–13.5 litre min −1 for MostCare-CO). A good correlation between ThD-CO and MostCare-CO was observed ( R = 0.93). The mean bias between the two techniques was −0.26 litre min −1 (sd 0.98 litre min −1 ) and the 95% limits of agreement were −2.22 to 1.70 litre min −1 . The percentage of error was 25%. Pearson's R was 0.94, 0.92, and 0.93 at T1, T2, and T3, respectively. Conclusions MostCare-CO and ThD-CO showed a good agreement at each time of the study. The reliability of the MostCare system was not affected by the vascular tone changes produced by a norepinephrine infusion.

An Uncalibrated Pulse Contour Method to Measure Cardiac Output During Aortic Counterpulsation

Less-invasive monitoring systems, such as pulse contour methods, are increasingly being used to estimate cardiac output (CO). However, alterations in the arterial waveform caused by intraaortic balloon pump counterpulsation may affect the ability of pulse contour algorithms to determine CO. We investigated the reliability of an uncalibrated pulse contour method, the MostCare system, in patients with cardiac failure receiving intraaortic balloon pump counterpulsation by comparing its measurements of CO with those determined by an intermittent thermodilution method. The study included 15 patients requiring hemodynamic support with an intraaortic balloon pump after coronary artery bypass graft surgery. A pulmonary artery catheter was inserted and CO was determined by bolus thermodilution (ThD-CO). The MostCare device was directly connected to the standard monitoring system for analysis of the radial artery pressure wave and computation of CO (MostCare-CO). Data were collected at 3 different intraaortic balloon pump rates (1:1, 1:2, 1:4) and after intraaortic balloon pump removal. One hundred six pairs of ThD-CO and MostCare-CO measurements were analyzed. There was a good correlation between ThD-CO and MostCare-CO (r = 0.90, 95% confidence interval [CI] = 0.86-0.93; P < 0.001). The mean bias of all CO measurements corrected for repeated measures was -0.2 L/min with limits of agreements of -1.31 to 0.91 L/min (lower 95% CI, -1.72 to -0.90; upper 95% CI, 0.50-1.32) and a relative percentage error of 24. There were close agreements between ThD-CO and MostCare-CO at the different intraaortic balloon pump rate settings. Changes in CO were calculated separately for the 2 methods and data comparison showed a correlation of 0.82 (95% CI = 0.76-0.87; P < 0.001) and a mean bias of 0.14 L/min with limits of agreement of -1.31 to 1.59 L/min (lower 95% CI, -1.62 to -1.00; upper 95% CI, 1.28-1.90). The MostCare system provided measurements of CO that were comparable to ThD-CO in patients assisted with an intraaortic balloon pump. The reliability of the MostCare system is not significantly affected by changes in arterial waveform morphology caused by inflation and deflation of the intraaortic balloon pump.

Comparison between an uncalibrated pulse contour method and thermodilution technique for cardiac output estimation in septic patients

The purpose of this study was to evaluate the reliability of a new uncalibrated pulse contour method, the MostCare, in determining cardiac output (CO) in septic patients. Thirty patients with septic shock admitted to an intensive care unit, receiving a norepinephrine infusion and requiring haemodynamic monitoring with a pulmonary artery catheter, were prospectively enrolled. Thermodilution measurements of CO (ThD-CO) were considered as the 'gold standard'. MostCare was connected to the monitoring system of the radial arterial pressure waveform to obtain a continuous CO calculation (MostCare-CO). ThD-CO and MostCare-CO measurements were recorded at three different haemodynamic states: baseline (T1), after raising mean arterial pressure (MAP) to 90 mm Hg by increasing the norepinephrine infusion (T2), and after returning the MAP to baseline value by decreasing vasopressor therapy (T3). A Bland-Altman and linear regression analyses were performed. A total of 90 paired ThD-CO and MostCare-CO measures were obtained (range 4.1-13.9 litre min(-1) for ThD-CO and 4.5-13.5 litre min(-1) for MostCare-CO). A good correlation between ThD-CO and MostCare-CO was observed (R = 0.93). The mean bias between the two techniques was -0.26 litre min(-1) (sd 0.98 litre min(-1)) and the 95% limits of agreement were -2.22 to 1.70 litre min(-1). The percentage of error was 25%. Pearson's R was 0.94, 0.92, and 0.93 at T1, T2, and T3, respectively. MostCare-CO and ThD-CO showed a good agreement at each time of the study. The reliability of the MostCare system was not affected by the vascular tone changes produced by a norepinephrine infusion.

Continuous cardiac output monitoring with an uncalibrated pulse contour method in patients supported with mechanical pulsatile assist device

We evaluated the accuracy of an uncalibrated pulse contour method called Pressure Recording Analytical Method (PRAM) compared with continuous thermodilution for cardiac output (CO) monitoring in patients implanted with a pulsatile left ventricular assist device (LVAD). Twelve adult patients implanted with the HeartMate I-XVE device were studied. CO was simultaneously evaluated by PRAM and by continuous thermodilution. Blood flow values displayed by the LVAD's console were also used for the comparison. Bland-Altman and linear regression analyses were applied. A total of 72 CO measurements (range 3.8-6.7 l/min) were obtained. Mean CO was 5.23±0.70 l/min for the 'hot' pulmonary thermodilution (ThD-CCO) method, 5.28±0.63 l/min for PRAM and 4.83±0.67 l/min for LVAD-CO. A high correlation (r=0.90), a good agreement (mean bias -0.04 l/min, precision ±0.38 l/min) and a low percentage of error (7.3%) were observed between PRAM-CO and ThD-CCO. A good correlation was found between LVAD-CO and either ThD-CCO (r=0.88) or PRAM-CO (r=0.86), but an overestimation of 10% was observed for both PRAM-CO (mean bias -0.44 l/min) and ThD-CCO (mean bias -0.40 l/min). Our results demonstrated good agreements between PRAM-CO, ThD-CCO and LVAD-CO. PRAM derives CO from a peripheral artery without calibration and may be a complementary tool in the hemodynamic assessment of patients supported with a VAD.

The ‘left’ ventricle during pulsatile mechanical assistance: reliability of cardiac output monitoring with an uncalibrated pulse contour method

The determination of cardiac output (CO) during mechanical circulatory support (MCS) is crucial since low-output syndrome is the main cause of death in such patients. A new uncalibrated pulse contour method (PCM) named PRAM (pressure recording analytical method) has recently been introduced in the clinical practice and validated in animals, humans, and patients assisted with axial flow pumps. The figure …