This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (15) Citing Articles via Google Scholar Google Scholar Articles by Mayer, J. Articles by Suttner, S. Search for Related Content PubMed PubMed Citation Articles by Mayer, J. Articles by Suttner, S. Related Collections Cardiovascular Monitoring (Cardiac) Technology

---

TECHNOLOGY, COMPUTING, AND SIMULATION

Cardiac Output Derived from Arterial Pressure Waveform Analysis in Patients Undergoing Cardiac Surgery: Validity of a Second Generation Device

From the Department of Anesthesiology and Intensive Care Medicine, Klinikum Ludwigshafen, Germany.

Address correspondence and reprint requests to Dr. med. Jochen Mayer, Department of Anesthesiology and Intensive Care Medicine, Klinikum Ludwigshafen, Bremserstr. 79, 67063 Ludwigshafen, Germany. Address e-mail to j-mayer{at}gmx.de.

	Abstract

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
BACKGROUND: The performance of a recently introduced, arterial waveform-based device for measuring cardiac output (CO) without the need of invasive calibration (FloTrac/Vigileo^TM) has been controversial. We designed the present study to assess the validity of an improved version of this monitoring technique compared with intermittent thermodilution CO measurement using a pulmonary artery catheter in patients undergoing cardiac surgery.

METHODS: Forty ASA III patients scheduled for elective coronary artery bypass grafting with cardiopulmonary bypass (CPB) were studied. Simultaneous CO measurements by bolus thermodilution and the FloTrac/Vigileo device were obtained after induction of anesthesia (T1), before CPB (T2), after CPB (T3), after sternal closure (T4), on arrival in the intensive care unit (T5), 4 h (T6), 8 h (T7), and 24 h after surgery (T8). CO was indexed to the body surface area (cardiac index, CI). A percentage error of 30% or less was established as the criterion for method interchangeability.

RESULTS: Two hundred and eighty-two data pairs were analyzed. Thermodilution CI ranged from 1.2 to 4.1 L · min^–1 · m^–2 (mean 2.5 ± 0.54 L · min^–1 · m^–2). Bias and precision (1.96 sd of the bias) were 0.19 L · min^–1 · m^–2 and ± 0.60 L · min^–1 · m^–2, resulting in an overall percentage error of 24.6%. Subgroup analysis revealed a percentage error of 28.3% for data pairs obtained intraoperatively (T1–4) and 20.7% in intensive care unit (T5–8).

CONCLUSION: CI values obtained by the improved, second generation semiinvasive arterial waveform device showed good intraoperative and postoperative agreement with intermittent pulmonary artery thermodilution CI measurements in patients undergoing coronary artery bypass graft surgery.

	Introduction

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
In the critically ill, determination of cardiac output (CO) can be important to either confirm diagnosis or guide therapy. Invasive techniques such as pulmonary artery catheterization (PAC) have become well established, but complications have led to an increasing demand for alternative, less invasive methods.1 Arterial pulse wave analysis is less invasive and validation studies have shown good correlation overall compared with pulmonary artery thermodilution.2–4 However, invasive calibration by transpulmonary thermodilution, lithium dilution or previous determination of the aortic diameter is usually required to compensate for interindividual differences of arterial compliance.5,6 In previous attempts to obtain CO from arterial pressure waveform analysis without invasive calibration based on the waveform of a finger artery, only a fair agreement compared with thermodilution measurements could be achieved.7,8 A recently introduced device (FloTrac/Vigileo^TM, Edwards Lifesciences, Irvine, CA) calculates continuous CO on arterial pressure waveform characteristics and uses individual demographic data to estimate arterial compliance; hence, external calibration is not required. However, the first studies analyzing the validity of this device showed varying results. Three controlled peer-reviewed studies9–11 and one pilot study12 have been performed using earlier software versions. Three prior studies did not recommend routine use9,11,12 and one found satisfactory agreement of the new device with intermittent and continuous thermodilution.10 Substantial improvement and a refined algorithm to calculate CO have subsequently been developed. The rate of adjustment of the internal variable estimating vascular tone was reduced from 10 min to 60 s with the new software version, combined with reduction of pulsewave detection noise. This study was designed to reevaluate the agreement of CO measurements derived from the second generation arterial pressure waveform device compared with intermittent pulmonary artery thermodilution CO monitoring in patients undergoing cardiac surgery.

	METHODS

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
After IRB approval and obtaining written informed consent, 40 adult patients of ASA classification III scheduled for elective coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) and routine PAC placement were studied. Exclusion criteria were permanent cardiac arrhythmias, a permanent pacemaker, the need for mechanical cardiac support, severe peripheral vascular disease, and valvular dysfunction. All patients underwent preoperative transthoracic echocardiography, and no valvular dysfunctions were documented.

Premedication consisted of 0.1 mg/kg midazolam orally. Routine access to the left or right radial artery was established (Leadercath 20G, Vygon, Ecouen, France) and connected to the Vigileo^TM monitor (Edwards Lifesciences, Irvine, CA; software version 1.10) via the FloTrac^TM pressure transducer. Induction of anesthesia was performed with sufentanil 1.5 µg/kg, midazolam 0.07 mg/kg, and pancuronium 0.01 mg/kg. After intubation of the trachea, the lungs were ventilated with 50% oxygen in air. Ventilation was controlled with a tidal volume of 10 mL/kg and a positive end-expiratory pressure (PEEP) of 5 mm Hg. The ventilatory rate was adjusted to maintain an arterial partial pressure of carbon dioxide of 32–42 mm Hg and arterial pH between 7.35 and 7.45. A balloon tipped, flow-directed PAC (7.5F, Edwards, Irvine, CA) was placed via the right internal jugular vein and the correct position was confirmed by pressure tracings and by routine chest radiograph immediately after admission to the intensive care unit (ICU). CPB was provided using a nonpulsatile flow rate of 2.4 L · min^–1 · m^–2 and temperature was kept at mild hypothermia (bladder temperature >33°C). All intravascular pressure measurements were referenced to the midchest level and thermodilution CO measurements with the PAC were performed by experienced staff with constant injections of 10 mL of ice-cold 0.9% saline. The validity of every temperature curve was judged visually on the attached monitor. A minimum of four consecutive measurements over the entire respiratory cycle was obtained and a difference of <10% between the measurements was accepted for data collection. The mean thermodilution CO was calculated and compared with the mean CO value derived from the Vigileo monitor over the same period. The shape of the arterial curve was checked visually to reduce the chance of error because of damping. If arrhythmias occurred during the measurements, the results were discarded and measurements were repeated. The measured CO values were indexed to the body surface area (cardiac index, CI) by dividing the CO by the body surface area.

Postoperatively, all patients were transferred to the ICU and controlled mechanical ventilation was continued for at least 4 h. Peak airway pressures were adjusted to deliver a constant tidal volume of 10 mL/kg body weight; inspiratory/expiratory time ratio was set to 1:2, and a PEEP of 5 mm Hg was used. Sedation consisted of a continuous propofol infusion of 0.5–1.5 mg · kg^–1 · h^–1. Tracheal extubation was performed when body temperature was >36°C, the patients breathed spontaneously with adequate blood gas variables, and hemodynamics were stable.

Thermodilution CI (TDCI) and CI measurements using the FloTrac/Vigileo monitor (APCI) were obtained simultaneously after induction of anesthesia (T1), before (T2) and after (T3) CPB, after sternal closure (T4), on arrival in ICU (T5), after 4 h (T6), after 8 h (T7), and 24 h after surgery (T8). CI measurements and data collection were performed by two anesthesiologists who were blinded to the corresponding CO measurement of the other method.

Statistical analysis was performed using the method described by Bland and Altman.13 Bias was defined as the mean difference between TDCI and APCI values. Precision was represented by the upper and lower limits of agreement. The limits of agreement were calculated as the bias (1.96 sd) defining the range in which 95% of the differences between the two methods were expected to lie. The percentage error (2 sd of the bias/mean CI100) was calculated according to Critchley and Critchley for comparison of CO values,14 and set as the decisive criterion for interchangeability of the two methods. The mean CI values derived from thermodilution versus arterial waveform analysis were compared using a paired Student's t-test. Data are presented as mean (sd), unless otherwise stated. P < 0.05 was considered statistically significant.

	RESULTS

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
From 40 patients included in the study, 282 data pairs were analyzed. Two patients needed mechanical cardiac support after CPB, eight patients showed permanent cardiac arrhythmias intraoperatively or in ICU and measurements during these periods were discarded. Basic demographic data as well as data from anesthesia and surgery are listed in Table 1. Hemodynamics during CO determination and cardiocirculatory therapy are listed in Tables 2 and 3 respectively. TDCI ranged from 1.2 to 4.1 L · min^–1 · m^–2 (mean 2.4 ± 0.54 L · min^–1 · m^–2) and from 1.6 to 4.0 L · min^–1 · m^–2 (mean 2.6 ± 0.49 L · min^–1 · m^–2) for APCI. Bias and precision were 0.19 L · min^–1 ·m^–2 and ± 0.60 L · min^–1 · m^–2 with a percentage error of 24.6% for all CI data pairs (Fig. 1). Subgroup analysis revealed a percentage error of 28.3% for values obtained intraoperatively (T1–4, Fig. 2) with a bias and precision of 0.19 and 0.68 L · min^–1 · m^–2. In ICU (T5–8), bias and precision were 0.21 and 0.51 L · min^–1 · m^–2, leading to a percentage error of 20.7% (Fig. 2). Data stratification into groups of mechanically ventilated patients and patients breathing spontaneously resulted in a percentage error of 25.9% during ventilation and 24.1% after tracheal extubation. Bias and precision were 0.19 L · min^–1 · m^–2 and 0.63 L · min^–1 · m^–2 and 0.23 L · min^–1 · m^–2 and 0.60 L · min^–1 · m^–2 respectively (Fig. 2). Analysis of data pairs in patients with CI 2.0 L · min^–1 · m^–2 (n = 52) showed a percentage error of 27.9% with a mean CI difference of 0.32 L · min^–1 · m^–2 and a precision of ± 0.53 L · min^–1 · m^–2 (Fig. 2). CI was calculated separately for each method and data comparison revealed a bias of 0.04 L · min^–1 · m^–2 and a precision of ± 0.91 L · min^–1 · m^–2 (Fig. 2). Bias, precision and percentage error for every data point (T1–8) are summarized in Figure 3.

View larger version (13K): [in this window] [in a new window]   Figure 1. Bland–Altman analysis of cardiac index (CI) of all enrolled patients. PA = pulmonary artery thermodilution, Vigileo = FloTrac/VigileoTM device.

View larger version (22K): [in this window] [in a new window]   Figure 2. Bland–Altman analysis of cardiac index (CI) intraoperatively (A), in ICU (B), in patients during mechanical ventilation (C) and spontaneously breathing (D), CI 2 L · min–1 · m–2 (E), and CI comparison (F). ICU = intensive care unit, PA = pulmonary artery thermodilution, Vigileo = FloTrac/VigileoTM device.

View larger version (13K): [in this window] [in a new window]   Figure 3. Bias, precision, and percentage error for every data point (T1–8). The dotted line is the 30% limit of acceptance. GA = general anesthesia, CPB = after cardiopulmonary bypass, ICU = in intensive care unit.

	DISCUSSION

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
Arterial pressure waveform analysis to determine CO has already been introduced into clinical practice. Commercially available devices include the PiCCO-system (PiCCO^TM, Pulsion Medical Systems, Munich, Germany) or the LiDCO-system (LiDCO^TM-plus, LiDCO Ltd., Cambridge, UK), which both require invasive calibration and recalibration by either transpulmonary thermodilution or lithium dilution after a certain time to compensate for interindividual differences in vascular compliance.5,15 The Modelflow- technique (Finapres Medical Systems, Amsterdam, NL) requires calibration by thermodilution or determination of the aortic diameter.6 A recently developed device (FloTrac/Vigileo) offers the possibility of uncalibrated continuous CO measurements on the basis of arterial waveform analysis combined with simple usability. Recent software improvements consist of a more frequent recalculation of an internal variable estimating vascular tone combined with reduction of pulsewave detection noise.

We used the method described by Critchley and Critchley14 to compare CO measurements, as this not only incorporates the error of the method to be tested, but also adjustments for errors in the reference method itself. These authors concluded that a percentage error of 30% between the test and reference method indicates that the test method is no less accurate than the reference method. In our study, we found an overall percentage error of 24.6% for all data pairs, and it can therefore be characterized as comparable with TDCI. A percentage error of <30% implies, based on an absolute error of 10%–20% of the TDCI method, an absolute error of 20% or less for the APCI device. Separate analysis of CO data obtained during the ICU period showed better agreement with a percentage error of 20.7%, whereas intraoperative measurements revealed a percentage error of 28.3%. This is still below the 30% limit of acceptance but displays differences in performance we found in the perioperative time course. As described previously,11 vessel impedance, peripheral vascular resistance, and arterial compliance are the basis of arterial waveform analysis for measuring CO. Sources of error include interindividual differences in aortic impedance, an important variable to calculate stroke volume,16 or reflections of the arterial pulse contour due to vessel tapering, bifurcations and caliber changes, which may corrupt the peripheral arterial pulsewave signal.17 Since the percentage error shows that the agreement of the APCI with TDCI is within our ability to measure the error, the aforementioned malfunction sources of uncalibrated arterial waveform analysis seem to be attenuated by the improved algorithm of the APCI device. Peripheral arterial pulse wave is interaction between the left ventricular output and the capacitance of the vascular tree18 and, apart from fluid status or temperature, the use of vasoactive drugs causes changes in the systemic vascular system. This might result in a higher bias of the APCI device in times of higher vasoactive drug usage. Nonetheless, no restrictions were made in the study protocol with regard to cardiocirculatory treatment to be able to analyze the clinical relevance of this effect.

After weaning from CPB, bolus administration of inotropes (epinephrine and norepinephrine 2.5–10 µg) was associated with the lowest agreement between APCI and TDCI, leading to a percentage error of 32.2%. After separation from CPB with cardiac arrest, central–peripheral arterial pressure gradients have been shown, resulting in differences in the shape of the arterial pressure wave.19,20 This may be another reason for the higher bias after CPB. This mechanism was observed to resolve after approximately 20 min.21 Other potential causes for the increased error immediately after CPB could be the sensitivity of TDCI to thermal changes as fluids are administered and the patient rewarms. Also, the comparison of an intermittent measurement (TDCI) to a continuous measurement (APCI) has inherently more error in a rapidly fluctuating environment. In the ICU, where alterations in fluid input, patient temperature, and continuous infusion of inotropes are less dynamic, the error between APCI and TDCI was reduced when compared with intraoperative CI data. Patients with low CI often have a higher demand of inotropes, which might explain the slightly higher bias in this subgroup. Mechanical ventilation appears to have no impact on the bias of APCI with the ventilator settings used in our study (tidal volume 10 mL/kg body weight, PEEP max 5 mm H₂O, and an inspiratory/ expiratory time ratio of 1:2).

Results of other studies dealing with the same APCI device showed varying results. Sander et al.9 found a total percentage error of 54% between FloTrac/ Vigileo-derived CO and CO measured by bolus thermodilution in 108 data pairs. The authors did not state the software version of the FloTrac/Vigileo used, but as their results are overall comparable with the results of our previous study,11 they most probably used a first generation device. They also found a better agreement for patients in the ICU than intraoperatively, which supports the aforementioned thesis that the bias is markedly influenced by changes in arterial vascular tone. Opdam et al.12 investigated the performance of APCI compared with TDCI after CABG surgery in the ICU and reported a limited correlation of r² = 0.26. They also tested different arterial sites and found the femoral artery to be superior to the brachial and radial insertion site. However, only six patients were enrolled, the software version used was not provided and the percentage error was not calculated in this study. Manecke and Auger10 compared 295 measurement pairs of CO in patients who did not receive any vasoactive treatment and found a bias of 0.55 L/min and a precision of 0.98 L/min. Unfortunately, they did not state the software version of the algorithm and percentage error was not given.

In light of our previous study11 that provided a comparable setting, the refined algorithm of the FloTrac/Vigileo device showed a significantly improved performance. The detected bias of 0.19 L · min^–1 · m^–2 for all CI data pairs is an improvement of almost 60% compared with 0.46 L · min^–1 · m^–2,11 and the percentage error decreased from 45.9% to 24.6%. In patients with low CI, bias and percentage error decreased from 0.67 L · min^–1 · m^–2 and 56.4% to 0.32 L · min^–1 · m^–2 and 27.9% respectively.

Apart from CO, the different, less invasive technique of the FloTrac/Vigileo device cannot provide data about cardiac filling pressures, such as pulmonary artery pressure, pulmonary artery occlusion pressure, and mixed venous oxygen saturation, which might be useful in particular patients.

In conclusion, the second generation FloTrac/ Vigileo device offers less invasive and overall reliable measurement of CO combined with easy usability during sinus rhythm in patients undergoing CABG surgery compared with pulmonary artery thermodilution. However, additional work should be done to improve the response after bolus application of vasoactive drugs, and to prove reliability in different clinical settings.

	Footnotes

 
Accepted for publication November 7, 2007.

	REFERENCES

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 

1. Chaney JC, Derdak S. Minimally invasive hemodynamic monitoring for the intensivist: current and emerging technology. Crit Care Med 2002;30:2338–45[Web of Science][Medline]
2. Rodig G, Prasser C, Keyl C, Liebold A, Hobbhahn J. Continuous cardiac output measurement: pulse contour analysis vs. thermodilution technique in cardiac surgical patients. Br J Anaesth 1999;82:525–30[Abstract/Free Full Text]
3. Godje O, Hocke K, Goetz AE, Felbinger TW, Reuter DA, Reichart B, Friedl R, Hannekum A, Pfeiffer UJ. Reliability of a new algorithm for continuous cardiac output determination by pulse contour analysis during hemodynamic instability. Crit Care Med 2002;30:52–8[Web of Science][Medline]
4. Pittman J, Bar-Yosef S, Sum Ping J, Sherwood M, Mark J. Continuous cardiac output monitoring with pulse contour analysis: a comparison with lithium indicator dilution cardiac output measurement. Crit Care Med 2005;33:2015–21[Web of Science][Medline]
5. Yamashita K, Nishiyama T, Yokoyama T, Abe H, Manabe M. Cardiac output by PulseCO is not interchangeable with thermodilution in patients undergoing OPCAB. Can J Anaesth 2005;52:530–4[Web of Science][Medline]
6. de Vaal JB, Wilde RBP, van den Berg PC, Schreuder JJ, Jansen JR. Less invasive determination of cardiac output from arterial pressure by aortic diameter-calibrated pulse contour. Br J Anaesth 2005;95:326–31[Abstract/Free Full Text]
7. Hirschl MM, Binder M, Gwechenberger M, Herkner H, Bur A, Kittler H, Laggner AN. Noninvasive assessment of cardiac output in critically ill patients by analysis of the finger blood pressure waveform. Crit Care Med 1997;25:1909–14[Web of Science][Medline]
8. Hirschl MM, Kittler H, Woisetschläger C, Siostrzonek P, Staudinger T, Kofler J, Oschatz E, Bur A, Gwechenberger M, Laggner AN. Simultaneous comparison of thoracic bioimpedance and arterial pulse waveform-derived cardiac output with thermodilution measurement. Crit Care Med 2000;28:1798–802[Web of Science][Medline]
9. Sander M, Spies CD, Grubitzsch H, Foer A, Muller M, von Heymann C. Comparison of uncalibrated arterial waveform analysis in cardiac surgery patients with thermodilution cardiac output measurements. Crit Care 2006;10:R164[Medline]
10. Manecke GR Jr, Auger WR. Cardiac output determination from the arterial pressure wave: clinical testing of a novel algorithm that does not require calibration. J Cardiothorac Vasc Anesth 2007;21:3–7[Web of Science][Medline]
11. Mayer J, Boldt J, Schollhorn T, Rohm KD, Mengistu AM, Suttner S. Semi-invasive monitoring of cardiac output by a new device using arterial pressure waveform analysis: a comparison with intermittent pulmonary artery thermodilution in patients undergoing cardiac surgery. Br J Anaesth 2007;98:176–82[Abstract/Free Full Text]
12. Opdam HI, Wan L, Bellomo R. A pilot assessment of the FloTrac^TM cardiac output monitoring system. Intensive Care Med 2007;33:344–9[Web of Science][Medline]
13. Bland JM, Altman DG. Statistical method for assessing agreement between two methods of clinical measurements. Lancet 1986;8476:307–10
14. Critchley LAH, Critchley JAJH. A meta-analysis of studies using bias and precision statistics to compare cardiac output measurement techniques. J Clin Monit Comput 1999;15:85–91[Medline]
15. Pearse RM, Ikram K, Barry J. Equipment review: an appraisal of the LiDCO^TM plus method of measuring cardiac output. Crit Care 2004;8:190–5[Web of Science][Medline]
16. Wesseling R, de Witt B, Ty Smith N. A simple device for the continuous measurement of cardiac output. Adv Cardiovas Phys 1983;5:16–52
17. O'Rourke NF, Yaginuma T. Wave reflections and the arterial pulse. Arch Intern Med 1984;144:366–71[Abstract/Free Full Text]
18. Sujatha P, Mehta P, Dhar A, Sarkar D, Meharwal ZS, Trehanet N. Comparison of cardiac output in OPCAB: bolus thermodilution technique versus pulse contour analysis. Ann Card Anaesth 2006;9:44–8[Medline]
19. Mohr R, Lavee J, Goor DA. Inaccuracy of radial artery pressure measurement after cardiac operations. J Thorac Vasc Surg 1987;94:286–90
20. Manecke GR Jr, Parimucha M, Stratmann G, Wilson WC, Roth DM, Auger WR, Kerr KM, Jamieson SW, Kapelanski DP, Mitchel MM. Deep hypothermic circulatory arrest and the femoral-to-radial arterial pressure gradient. J Cardiothor Vasc Anesth 2004;18:175–9[Web of Science][Medline]
21. Stern DH, Gerson JI, Allen FB, Parker FB. Can we trust the direct radial artery pressure immediately following cardiopulmonary bypass? Anesthesiology 1985;62:557–61[Web of Science][Medline]

This article has been cited by other articles:

				J. Mayer, J. Boldt, R. Beschmann, A. Stephan, and S. Suttner Uncalibrated arterial pressure waveform analysis for less-invasive cardiac output determination in obese patients undergoing cardiac surgery Br. J. Anaesth., August 1, 2009; 103(2): 185 - 190. [Abstract] [Full Text] [PDF]

				R. Chatti, S. de Rudniki, S. Marque, A. S. Dumenil, A. Descorps-Declere, A. Cariou, J. Duranteau, M. Aout, E. Vicaut, and B. P. Cholley Comparison of two versions of the Vigileo-FloTracTM system (1.03 and 1.07) for stroke volume estimation: a multicentre, blinded comparison with oesophageal Doppler measurements Br. J. Anaesth., April 1, 2009; 102(4): 463 - 469. [Abstract] [Full Text] [PDF]

				F. Compton and J.-H. Schafer Noninvasive Cardiac Output Determination: Broadening the Applicability of Hemodynamic Monitoring Seminars in Cardiothoracic and Vascular Anesthesia, March 1, 2009; 13(1): 44 - 55. [Abstract] [PDF]

				M. Cannesson, H. Musard, O. Desebbe, C. Boucau, R. Simon, R. Henaine, and J.-J. Lehot The Ability of Stroke Volume Variations Obtained with Vigileo/FloTrac System to Monitor Fluid Responsiveness in Mechanically Ventilated Patients Anesth. Analg., February 1, 2009; 108(2): 513 - 517. [Abstract] [Full Text] [PDF]

				G. Biancofiore, L. A. H. Critchley, A. Lee, L. Bindi, M. Bisa, M. Esposito, L. Meacci, R. Mozzo, P. DeSimone, L. Urbani, et al. Evaluation of an uncalibrated arterial pulse contour cardiac output monitoring system in cirrhotic patients undergoing liver surgery Br. J. Anaesth., January 1, 2009; 102(1): 47 - 54. [Abstract] [Full Text] [PDF]

				T. W. L. Scheeren, C. Wiesenack, F. D. Compton, B. Zukunft, C. Hoffmann, W. Zidek, and J.-H. Schaefer Performance of a minimally invasive cardiac output monitoring system (Flotrac/Vigileo) Br. J. Anaesth., August 1, 2008; 101(2): 279 - 280. [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (15) Citing Articles via Google Scholar Google Scholar Articles by Mayer, J. Articles by Suttner, S. Search for Related Content PubMed PubMed Citation Articles by Mayer, J. Articles by Suttner, S. Related Collections Cardiovascular Monitoring (Cardiac) Technology