Arterial Pressure Waveform Analysis Research Articles

Continuous arterial pressure waveform monitoring in pediatric cardiac transplant, cardiomyopathy and pulmonary hypertension patients

A continuous cardiac output monitor based on arterial pressure waveform (FloTrac/Vigileo; Edwards Lifesciences, Irvine, CA) is now approved for use in adults but not in children. This device is minimally invasive, calculates cardiac output continuously and in real time, and is easy to use. Our study sought to validate the FloTrac with the pulmonary artery catheter (PAC) intermittent thermodilution technique in pediatric cardiac patients. This was a prospective pilot study comparing cardiac output measurements obtained via the FloTrac and arterial pressure waveform analysis with intermittent thermodilution. Subjects carried the diagnosis of pulmonary hypertension or cardiomyopathy, or were in the postoperative course after orthotopic heart transplantation. Enrolled in the study were 31 subjects, and 136 data points were obtained. The age range was 8 months to 16 years. The mean body surface area (BSA) was 1.1 m(2). Bland-Altman plots for the mean cardiac outputs of all subjects with a BSA ≥ 1 m(2) showed limits of agreement of -2.7 to 8.0 l/min (± 5.4 l/min). Patients with a BSA ≤ 1 m(2) demonstrated even wider limits of agreement (± 8.5 l/min). The intraclass correlation for the PAC was 0.929 and 0.992 for the FloTrac. There was poor agreement between the PAC and FloTrac in measuring cardiac output in a population of children with pulmonary hypertension or cardiomyopathy, or after cardiac transplantation. This is in contrast to adult studies published thus far. This suggests that the utility of the FloTrac and measurements obtained from arterial pulse wave analysis in children is uncertain at this time.

Comparison of two methods for cardiac output measurement in critically ill patients

The aim of recent haemodynamic monitoring has been to obtain continuous and reliable measures of cardiac output (CO) and indices of preload responsiveness. Many of these methods are based on the arterial pressure waveform analysis. The aim of our study was to assess the accuracy of CO measurements obtained by FloTrac/Vigileo, software version 1.07 and the new version 1.10 (Edwards Lifesciences LLC, Irvine, CA, USA), compared with CO measurements obtained by bolus thermodilution by pulmonary artery catheterization (PAC) in the intensive care setting. In 21 critically ill patients (enrolled in two University Hospitals), requiring invasive haemodynamic monitoring, PAC and FloTrac/Vigileo transducers connected to the arterial pressure line were placed. Simultaneous measurements of CO by two methods (FloTrac/Vigileo and thermodilution) were obtained three times a day for 3 consecutive days, when possible. The level of concordance between the two methods was assessed by the procedure suggested by Bland and Altman. One hundred and forty-one pairs of measurements (provided by thermodilution and by both 1.07 and 1.10 FloTrac/Vigileo versions) were obtained in 21 patients (seven of them were trauma patients) with a mean (sd) age of 59 (16) yr. The Pearson product moment coefficient was 0.62 (P<0.001). The bias was -0.18 litre min(-1). The limits of agreement were 4.54 and -4.90 litre min(-1), respectively. Our data show a poor level of concordance between measures provided by the two methods. We found an underestimation of CO values measured with the 1.07 software version of FloTrac for supranormal values of CO. The new software (1.10) has been improved in order to correct this bias; however, its reliability is still poor. On the basis of our data, we can therefore conclude that both software versions of FloTrac/Vigileo did not still provide reliable estimation of CO in our intensive care unit setting.

Cardiac Output Derived from Arterial Pressure Waveform Analysis in Patients Undergoing Cardiac Surgery

Cardiac Output Derived from Arterial Pressure Waveform Analysis in Patients Undergoing Cardiac Surgery

Continuous and less invasive cardiac output monitoring by long time interval analysis of a peripheral arterial blood pressure waveform with pulse transit time correction

Continuous and less invasive cardiac output monitoring by long time interval analysis of a peripheral arterial blood pressure waveform with pulse transit time correction

Accuracy of arterial pressure waveform analysis for cardiac output measurement in comparison with thermodilution methods in patients undergoing living donor liver transplantation

The aim of this study was to assess the accuracy of the first and third versions of arterial pressure waveform cardiac output (APCO(v.1.0) and APCO(v.3.0)) measurements in comparison with thermodilution methods in patients undergoing living donor liver transplantation. Twenty patients were anesthetized and mechanically ventilated. A radial arterial line was connected to a dedicated transducer for the APCO evaluation (FloTrac™). A pulmonary artery catheter was placed and connected to a computer system (Vigilance™) to measure intermittent thermodilution cardiac output (CO(TD)) and continuous cardiac output (CCO). A total of 138 measurements were analyzed. Bland-Altman analysis showed that the mean biases for CO(TD)-APCO(v.3.0), CO(TD)-APCO(v.1.0), and CO(TD)-CCO were 0.89, 1.73, and -0.79L/min, and the adjusted percentage errors were 37.5, 30.3, and 43%, respectively. While the variance for CO(TD)-APCO(v3.0) was greater, the accuracy (bias) improved by 0.8L/min as compared with CO(TD)-APCO(v1.0). The difference CO(TD)-APCO(v.3.0) became apparent when systemic vascular resistance was lower than 1000dyne×s/cm(5), especially below 700dyne×s/cm(5). These data suggest that the accuracy of APCO(v.3.0) has improved compared to APCO(v.1.0) due to the updated algorithm, but additional improvements should be evaluated, especially in patients undergoing living donor liver transplantation with low systemic vascular resistance.

Assessment of right ventricular afterload by pressure waveform analysis in acute pulmonary hypertension

To characterize hydraulic right ventricle (RV) afterload by pulmonary arterial pressure waveform analysis in an acute pulmonary hypertension (PH) model. Pulmonary artery (PA) flow and pressure were recorded in six anesthetized sheep. Acute isobaric PH was induced by phenylephrine (active) and PA mechanical constriction (passive). We estimated the amplitude of the forward and reflected pressure waves according to the inflection point. In most cases the inflection pressure was smooth, thus the inflection point was defined as the time at which the first derivative of pulmonary arterial pressure reached its first minimum. We calculated the input and characteristic (Z(C), time-domain Li method) impedances, the capacitance index (stroke volume/pulse pressure), the augmentation index (AI) (reflected pressure/pulse pressure), the fractional pulse pressure (pulse pressure/mean pressure) and the wasted energy generated by the RV due to wave reflection during ejection (E(W)). Pulse pressure, fractional pulse pressure, AI and Z(C) increased and capacitance index decreased during passive PH with respect to control (P < 0.05). In contrast, Z(C) and the capacitance index did not change and E(W) and the AI decreased during active PH. Pulse pressure correlated with E(W) and Z(C) and the AI was correlated with E(W) (r > 0.6, P < 0.05). PA pressure waveform analysis allows the quantification of the dynamic RV afterload. Prospective clinical studies will be necessary to validate this time-domain approach to evaluate the dynamic RV afterload in chronic PH.

Comparison of Uncalibrated Arterial Pressure Waveform Analysis with Continuous Thermodilution Cardiac Output Measurements in Patients Undergoing Elective Off-Pump Coronary Artery Bypass Surgery

Comparison of Uncalibrated Arterial Pressure Waveform Analysis with Continuous Thermodilution Cardiac Output Measurements in Patients Undergoing Elective Off-Pump Coronary Artery Bypass Surgery

Effect of the α 2-adrenoceptor antagonist yohimbine on vascular regulation of the middle cerebral artery and the ophthalmic artery in healthy subjects

There is evidence that vascular beds distal to the ophthalmic artery (OA) show vasoconstriction in response to a step decrease in systemic blood pressure (BP). The mediators of this response are mostly unidentified. The aim of the current study was to test the hypothesis that α2-adrenoreceptors may contribute to the regulatory process in response to a decrease in BP. In this randomized, double-masked, placebo-controlled study 14 healthy male volunteers received either 22 mg yohimbine hydrochloride or placebo. Beat-to-beat BP was measured by analysis of arterial pressure waveform; blood flow velocities in the middle cerebral artery (MCA) and the OA were measured with Doppler ultrasound. Measurements were done before, during and after a step decrease in BP. The step decrease in BP was induced by bilateral thigh cuffs at a suprasystolic pressure followed by a rapid cuff deflation. After cuff deflation, BP returned to baseline after 7–8 pulse cycles (PC). Blood velocities in the MCA returned to baseline earlier (4 PC) than BP indicating peripheral vasodilatation. Blood velocities in the OA returned to baseline later (15–20 PC) indicating peripheral vasoconstriction. Yohimbine did not affect the blood velocity response in the MCA, but significantly shortened the time of OA blood velocities to return to baseline values (6–7 PC, p < 0.05). In conclusion, our results indicate that yohimbine did not alter the regulatory response in the MCA, but modified the response of vascular beds distal to the OA. This suggests that α2-adrenoceptors play a role in the vasoconstrictor response of the vasculatures distal to the OA.

Reduced mortality with noninvasive hemodynamic monitoring of shock

Purpose This study compared clinical outcomes associated with exposure to pulmonary artery catheters (PACs), central venous catheters (CVCs), arterial pressure waveform analysis for cardiac output (APCO), or no central monitoring (NCM) in patients with shock. Materials and Methods We assessed 6929 consecutive patients from 2003 to 2006 within a surgical intensive care unit of a university hospital, identifying 237 mechanically ventilated patients with shock. Results Adjusted for severity of illness, use of APCO monitoring, compared with other options, was associated with reduced intensive care unit mortality (odds ratio [OR], 0.37; 95% confidence interval [CI], 0.18-0.77) and 28-day mortality (OR, 0.43; 95% CI, 0.22-0.85). Other monitors were not associated with changes of 28-day mortality (CVC: OR, 0.63; 95% CI, 0.34-1.17; PAC: OR, 0.78; 95% CI, 0.36-1.69) or were associated with increased risk (NCM: OR, 2.29; 95% CI, 1.14-4.61). There were significant differences in the fluid and vasoactive drug prescriptions among the groups. Conclusions This study supports an association between the use of APCO monitoring and reduction in mortality in shock compared with traditional methods of monitoring. Although it is impossible to exclude the role of unrecognized/unrecorded differences among the groups, these findings may result from differences in supportive care, directed by monitor technology.

Cardiac output derived from arterial pressure waveform analysis without calibration vs. thermodilution in septic shock: evolving accuracy of software versions

We studied the evolution of software in the accuracy of the FloTrac/Vigileo system to measure cardiac output less invasively from arterial pressure waveform analysis without calibration, in comparison with pulmonary artery catheter-derived thermodilution measurements, in patients with septic shock and presumed alterations in vascular tone. Nine patients who received a pulmonary artery catheter and were on mechanical ventilation and in sinus rhythm were monitored by the FloTrac/Vigileo. Paired cardiac output measurements by both techniques were analysed for 86 measurements in four patients using the 1.07 software version and 73 measurements in five subsequent patients using the later 1.10 version. For the 1.07 version, bias was -1.6 L min, precision 1.6 L min, limits of agreement -4.8-1.5 L min and error 48%. Measurements correlated at partial r equal to 0.32 (P = 0.003). For the 1.10 version, bias was -1.2 L min, precision 1.1 L min, limits of agreement -3.5-1.0 L min and error 32%. Measurements correlated at partial r equal to 0.90 (P < 0.001 vs. version 1.07). Differences were inversely related to mean cardiac output (P < 0.001, generalized estimating equations), particularly for software version 1.07 vs. 1.10 (P = 0.017, generalized estimating equation). Changes in thermodilution cardiac output over the course of time were also better tracked by the FloTrac/Vigileo when applying the latest software (P < 0.001, generalized estimating equation). Evolving software versions are thus better able to account for the effect of vascular tone on cardiac output measurements by less invasive waveform analyses without calibration (FloTrac/Vigileo), so that the latter may become useful in the haemodynamic monitoring of septic shock.

Cardiac output measured by arterial pressure waveform analysis without manual calibration (third generation software) compared with thermodilution in critical ill patients suffering from septic shock

Cardiac output measured by arterial pressure waveform analysis without manual calibration (third generation software) compared with thermodilution in critical ill patients suffering from septic shock

Performance of cardiac output measurement derived from arterial pressure waveform analysis in patients undergoing high-dose vasopressor-therapy

Performance of cardiac output measurement derived from arterial pressure waveform analysis in patients undergoing high-dose vasopressor-therapy

Comparison of Uncalibrated Arterial Pressure Waveform Analysis with Continuous Thermodilution Cardiac Output Measurements in Patients Undergoing Elective Off-Pump Coronary Artery Bypass Surgery

Monitoring of cardiac output is required during anesthesia for off-pump coronary artery bypass (OPCAB) surgery. Recently, FloTrac, a new device for arterial pressure waveform analysis for cardiac output (APCO) monitoring without external calibration, was developed. The authors have compared APCO with STAT-mode continuous cardiac output (SCCO) in patients undergoing OPCAB surgery. A clinical study. A university hospital (single institution). Thirty consecutive patients undergoing elective OPCAB surgery. Arterial pressure measurement with FloTrac, pulmonary arterial catheter insertion. APCO and SCCO measurements were recorded after pulmonary artery catheter insertion (T1), after sternotomy (T2), after heart positioning for left anterior descending artery anastomosis (T3, T4), after heart positioning for obtuse marginal artery anastomosis (T5, T6), after heart positioning for posterior descending artery anastomosis (T7, T8), and after sternal closure (T9). APCO and SCCO were compared using the Bland-Altman method and the percentage error by Critchley's criteria. SCCO and APCO ranged from 2.1 to 6.9 L/min and 1.2 to 7.4 L/min, respectively, and showed low correlation (r = 0.29). The overall bias by the Bland-Altman method between SCCO and APCO was -0.23 L/min, with a precision of -1.4 to 0.9 L/min, and the overall limits of agreement were -2.5 to 2.0 L/min. The overall mean CO was 4.0 ± 0.95 L/min. The overall percentage error between SCCO and APCO measurements was 57%. Uncalibrated APCO values do not agree with thermodilution SCCO and significantly overestimated the SCCO in patients undergoing OPCAB surgery. Further evaluation is required to verify the clinical acceptance of FloTrac APCO in OPCAB surgery.

Performance of cardiac output measurement derived from arterial pressure waveform analysis in patients undergoing triple-H-therapy of cerebral vasospasms after subarachnoidal hemorrhage

The validity of an arterial waveform-based device for measuring cardiac output (CO) without the need for invasive calibration (FloTrac/Vigileo) in patients needing large doses of vasoactive medication has not yet been thoroughly studied. We performed the present study to assess the validity of both the second-generation and the third-generation software compared with transpulmonary thermodilution CO measurement using the PiCCO technology in patients undergoing triple-H-therapy (hypertonia, hypervolemia, hemodilution) of cerebral vasospasms after subarachnoidal hemorrhage.

Goal-directed intraoperative therapy based on autocalibrated arterial pressure waveform analysis reduces hospital stay in high-risk surgical patients: a randomized, controlled trial

IntroductionSeveral studies have shown that goal-directed hemodynamic and fluid optimization may result in improved outcome. However, the methods used were either invasive or had other limitations. The aim of this study was to perform intraoperative goal-directed therapy with a minimally invasive, easy to use device (FloTrac/Vigileo), and to evaluate possible improvements in patient outcome determined by the duration of hospital stay and the incidence of complications compared to a standard management protocol.MethodsIn this randomized, controlled trial 60 high-risk patients scheduled for major abdominal surgery were included. Patients were allocated into either an enhanced hemodynamic monitoring group using a cardiac index based intraoperative optimization protocol (FloTrac/Vigileo device, GDT-group, n = 30) or a standard management group (Control-group, n = 30), based on standard monitoring data.ResultsThe median duration of hospital stay was significantly reduced in the GDT-group with 15 (12 - 17.75) days versus 19 (14 - 23.5) days (P = 0.006) and fewer patients developed complications than in the Control-group [6 patients (20%) versus 15 patients (50%), P = 0.03]. The total number of complications was reduced in the GDT-group (17 versus 49 complications, P = 0.001).ConclusionsIn high-risk patients undergoing major abdominal surgery, implementation of an intraoperative goal-directed hemodynamic optimization protocol using the FloTrac/Vigileo device was associated with a reduced length of hospital stay and a lower incidence of complications compared to a standard management protocol.Trial RegistrationClinical trial registration information: Unique identifier: NCT00549419

Comparison of continuous arterial pressure waveform analysis with the lithium dilution technique to monitor cardiac output in conscious dogs with systemic inflammatory response syndrome

To assess the agreement between cardiac output (CO) measured by use of arterial pressure waveform analysis (PulseCO) and lithium dilution (LiDCO) in conscious dogs with systemic inflammatory response syndrome (SIRS). 14 dogs with naturally occurring SIRS. Pulse power analysis was performed on critically ill patients with a PulseCO monitor. All measurements were obtained with an indwelling arterial line and in accordance with the manufacturer's instructions. Intermittent measurements of CO were obtained with the LiDCO method to validate the PulseCO measurements at initial calibration (baseline; time 0) and at 4, 8, 16, and 24 hours. The 2 methods for measuring CO were compared by use of Bland-Altman analysis. An error rate for the limits of agreement between the 2 methods of < 30% was defined as being acceptable. Bland-Altman analysis did not indicate good agreement between measurements obtained by use of the PulseCO and LiDCO methods, despite no significant change in cardiac index (CI) over time as measured with the LiDCO method. The percentage error for the overall difference in CI values between the PulseCO and LiDCO measurements was 122%, which indicated that the PulseCO method was not an acceptable means of CO measurement when compared with the LiDCO method for this patient population. Agreement between the PulseCO and LiDCO methods for measurement of CO was not acceptable at 4- and 8-hour intervals after calibration in conscious dogs with naturally occurring SIRS.

Cardiac Output Measurement by Arterial Pressure Waveform Analysis During Optimization of Biventricular Pacing After Cardiac Surgery

Biventricular pacing (BiVP) can optimize cardiac output (CO) in patients after cardiac surgery, so devices that calculate continuous CO from arterial pressure may be a useful tool. We investigated PulseCO for measuring CO during optimization by comparison with aortic flow probe measurement. Seven patients in the Biventricular Pacing After Cardiac Surgery (BiPACS) trial were studied. Before weaning from cardiopulmonary bypass, BiVP was initiated. After bypass, CO was optimized by varying atrioventricular pacing delay, ventricular site, and interventricular pacing delay with a randomized protocol. Continuous CO was measured by PulseCO and aortic flow probe. Reliability was estimated by Fleiss method and agreement assessed by Bland-Altman analysis. Compared with flow probe, PulseCO reliably measured changes in CO (intraclass correlation coefficient = 0.90) but underestimated the change (-4% + or - 17%). In contrast, changes in mean arterial pressure did not reflect changes in CO (intraclass correlation coefficient = 0.02). Thus, PulseCO can measure continuous CO in open-chest patients after cardiac surgery, whereas underestimating changes occurring across 10-second pacemaker changes. Further studies in the closed chest are indicated.

Uncalibrated Radial and Femoral Arterial Pressure Waveform Analysis for Continuous Cardiac Output Measurement: An Evaluation in Cardiac Surgery Patients

Arterial pressure waveform analysis is a less invasive alternative to the pulmonary artery catheter for continuous cardiac output (CO) measurement. Uncalibrated and calibrated systems are actually available (ie, the FloTrac/Vigileo system [Edwards Lifesciences, Irvine, CA] and the PiCCOplus system [Pulsion Medical Systems, Munich, Germany]). According to the FloTrac/Vigileo manufacturer, reliable measurements can be performed using any existing arterial catheter. The aim of this study was to evaluate CO determined by the FloTrac/Vigileo system using a radial (FCO(radial)) and femoral arterial catheter (FCO(femoral)) as well as the PiCCOplus system (PCO). Intermittent pulmonary artery thermodilution (ICO) was used as primary reference technique. A prospective clinical study. A teaching hospital, single center. Twenty-six cardiac surgery patients. Perioperative CO measurements. CO was assessed at predefined measurement points. FCO(radial), FCO(femoral), and PCO were recorded after the induction of anesthesia, after sternotomy, at skin closure, after intensive care unit transfer, and during intensive care unit stay 12 and 24 hours after study initiation. ICO was determined as the mean of 3 bolus injections. Bland-Altman analysis revealed comparable mean bias and limits of agreement for FCO(radial), FCO(femoral), and PCO when compared with ICO. There was a decreased agreement for all devices in the postoperative period. However, a consistently close agreement was observed for the direct comparison between FCO(radial) and FCO(femoral). Performance of the FloTrac/Vigileo system via radial as well as femoral access and the PiCCOplus monitoring for cardiac output measurement were comparable when tested against intermittent thermodilution in cardiac surgery patients.

Validity of an Arterial Pressure Waveform Analysis Device: Does the Puncture Site Play a Role in the Agreement With Intermittent Pulmonary Artery Catheter Thermodilution Measurements?

The measurement of cardiac output is a key element in the assessment of cardiac function. Recently, a pulse contour analysis-based device without need for calibration became available (FloTrac/Vigileo, Edwards Lifescience, Irvine, CA). This study was conducted to determine if there is an impact of the arterial catheter site and to investigate the accuracy of this system when compared with the pulmonary artery catheter using the bolus thermodilution technique (PAC). Prospective study. The operating room of 1 university hospital. Twenty patients undergoing cardiac surgery. CO was determined in parallel by the use of the Flotrac/Vigileo systems in the radial and femoral position (CO_rad and CO_fem) and by PAC as the reference method. Data triplets were recorded at defined time points. The primary endpoint was the comparison of CO_rad and CO_fem, and the secondary endpoint was the comparison with the PAC. Seventy-eight simultaneous data recordings were obtained. The Bland-Altman analysis for CO_fem and CO_rad showed a bias of 0.46 L/min, precision was 0.85 L/min, and the percentage error was 34%. The Bland-Altman analysis for CO_rad and PAC showed a bias of -0.35 L/min, the precision was 1.88 L/min, and the percentage error was 76%. The Bland-Altman analysis for CO_fem and PAC showed a bias of 0.11 L/min, the precision was 1.8 L/min, and the percentage error was 69%. The FloTrac/Vigileo system was shown to not produce exactly the same CO data when used in radial and femoral arteries, even though the percentage error was close to the clinically acceptable range. Thus, the impact of the introduction site of the arterial catheter is not negligible. The agreement with thermodilution was low.

Uncalibrated arterial pressure waveform analysis for less-invasive cardiac output determination in obese patients undergoing cardiac surgery

Uncalibrated arterial waveform analysis (FloTrac/Vigileo) uses standard arterial access to determine cardiac output (CO). Calculations are based on arterial waveform characteristics in combination with patient characteristic data to estimate individual arterial compliance. It has been shown that obesity is associated with altered arterial compliance independently of other risk factors. We conducted this study to assess the validity of measuring CO by the FloTrac/Vigileo device in obese patients undergoing cardiac surgery in comparison with bolus thermodilution technique. Fifteen obese patients with a BMI of > or = 30 and 23 non-obese patients (BMI 18-25) undergoing coronary artery bypass grafting (CABG) were included. Simultaneous CO measurements by bolus thermodilution and the FloTrac/Vigileo device (software version 1.10) were obtained intraoperatively after induction of anaesthesia, before cardiopulmonary bypass (CPB), after CPB, and after sternal closure. Measurements in the intensive care unit (ICU) were performed upon arrival in the ICU, after 4, 8, and 24 h after surgery. CO was indexed to the body surface area (cardiac index, CI). The analysis of 262 data pairs revealed a bias and precision of 0.19 and +/-0.66 litre min(-1) m(-2), resulting in a percentage error of 26.6%. Thermodilution CI values ranged from 1.1 to 4.2 litre min(-1) m(-2) [mean 2.4 (0.52) litre min(-1) m(-2)]. Subgroup analysis resulted in a percentage error of 29.8% in obese patients and 24.4% in patients with normal BMI. The semi-invasive FloTrac/Vigileo device was found to adequately agree with bolus pulmonary artery thermodilution in both obese and non-obese patients undergoing CABG.