If you wish to respond to a paper or other item already published in the BJA, please go to the abstract/full text version of that item and click on the link "E-Letters: Submit a response to the article".
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Arterial pressure wave form and cardiac output in dilated cardiomyopathy
- Usha Kiran, Khalid Zuber (6 June 2007)
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Author reply: Monitoring cardiac output with Flo Trac VigileoTM
- Jochen Mayer, Joachim Boldt, Thilo Schöllhorn, Kerstin D. Röhm, Andinet M. Mengistu, Stefan Suttner (30 March 2007)
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Monitoring cardiac output with Flo Trac VigileoTM
- Fabio Guarracino, m. stefani, f. lapolla, c. cariello, l. doroni, a. danella, r. baldassarri (13 March 2007)
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Usha Kiran, Head, Deptt of Cardiac Anaesthesia , Khalid Zuber
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Dear sir, We read with great interest the article by Mayer et. al. titled “semi- invasive monitoring of cardiac output (CO) by a new device using arterial pressure waveform analysis: a comparison with intermittent pulmonary artery thermodilution in patients undergoing cardiac surgery.”¹ We appreciate the authors' interest in comparing semi-invasive device with gold standard pulmonary artery thermodilution technique for CO monitoring in patients undergoing coronary artery bypass surgery and valvular surgery. Their results of the semi invasive device do not appear to fully agree with the invasive pulmonary artery thermodilution technique for determination of cardiac output in patients undergoing cardiac surgery. We agree with the authors view that the pulmonary artery thermodilution technique, although considered gold standard, is not without limitations. The limitations of this invasive thermodilution technique include arrhythmias, valvular lesions and rupture of pulmonary artery. We have recently used the semi-invasive device with vigileo monitor for measuring cardiac output and management of fluid and inotropes in a 47 years old patient with dilated cardiomyopathy (DCM). This patient was undergoing aorto-bifemoral bypass surgery for bilateral atherosclerotic aortoiliac occlusive disease. Aortic cross clamping at the time of vascular anastomosis results in increase in afterload which is associated with adverse hemodynamic changes such as decreased cardiac output, global ventricular dysfunction, and increased ventricular wall stress, central hypovolemia, metabolic acidosis, systemic vasodilation and excess catecholamine release. In this patient of DCM with an ejection fraction of 15% and impaired systolic and diastolic function it was essential to monitor CO to optimize inotrope and fluid administration. Inserting a pulmonary artery catheter in a case of DCM was not without dangers of severe arrhythmias so we decided to use the semi-invasive device with vigileo monitor. This device helped us in monitoring CO and thus rational use of fluid and inotrope in this sick and high risk patient. Fluid and inotrope were given as per the protocol deviced by E. Rivers et.al.². The total aortic cross clamp time was 27 minutes and the duration of surgery was 2 hours. The intraoperative and postoperative course remained uneventful. References 1. Mayer J., Boldt J., Schollhorn T., Rohm K. D., Mengistu A. M., 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 2. Rivers E., Nguyen B., Havstad S., Ressler J., Muzzin A., Knoblich B., Peterson E., Tomlanovich M.: Early goal-directed therapy in the treatment of severe sepsis and septic shock. N Engl J Med 2001; 345: 1368-77 Conflict of Interest:None declared |
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Jochen Mayer Deptartment of Anaesthesiology and Intensive Care Medicine, Klinikum Ludwigshafen, Ludwigshafen, Joachim Boldt, Thilo Schöllhorn, Kerstin D. Röhm, Andinet M. Mengistu, Stefan Suttner
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Editor- We thank Guarracino and colleges for their interest in our article (1). We agree with the authors that the VigileoTM system and the pulmonary artery catheter (PAC) might have different clinical indications in the near future. Nevertheless, every new tool to measure cardiac output (CO) has to be validated before it is introduced in clinical practice. We disagree, however, with the valve theory as a possible explanation for the bias Guarracino et al. raised in their letter. First, it was described in the methods section of our article that patients undergoing mitral or aortic valve surgery were excluded from analysis if they showed echocardigraphic signs of aortic or mitral dysfunction after surgery. Second, we are unaware how Guarracino et al. are able to criticise that 50% of the included patients had mitral or aortic insufficiency, as this is not mentioned in the article. Patients scheduled for valve replacement in fact included aortic and mitral valve stenosis and insufficiency at about the same percentage. Third, during preparation of our manuscript, we analysed patients undergoing valve surgery and coronary artery bypass grafting (CABG) separately. CABG patients (valve dysfunction preoperatively excluded) showed a percentage error of 45,1% with a bias of 0.44 litre min-1 m-2 and a precision of 1.24 litre min-1 m-2 which was comparable to patients undergoing valve surgery. Aortic and mitral valve dysfunction hence did neither bias thermodilution nor VigileoTM results in our study. Unfortunately, the authors did not present own data to substantiate their experience. Other recently published validation studies are in good correlation with our results (2) or show even worse results (3). References: (1) Mayer J et al. 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. (2) Sander M et al. Comparison of uncalibrated arterial waveform analysis in cardiac surgery patients with thermodilution cardiac output measurements. Critical Care 2006;10:R164 (doi:10.1186/cc5103) (3) Opdam HE et al. A pilot assessment of the FloTracTM cardiac output monitoring system. Intensive Care Med 2007;33:344-9 Conflict of Interest:None declared |
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Fabio Guarracino University Hospital of Pisa, Cardiothoracic Anaesthesia and ICU, m. stefani, f. lapolla, c. cariello, l. doroni, a. danella, r. baldassarri
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Editor — In their recent article (1) Mayer and colleagues compared a new device for semi-invasive determination of cardiac output (CO) (Flo Trac/VigileoTM , Edwards Lifesciences, Irvine, CA, USA) with the bolus thermodilution technique, considered the clinical "gold standard". They performed their measurements intraoperatively and postoperatively in patients undergoing cardiac surgery, and concluded that the new device, based on arterial pressure waveform analysis, doesn't appear to adequately measure continuous CO and is not recommended for routine use. In fact the authors found an overall percentage error of 45,9% in CO measurement compared with the "gold standard" method. We have been using the new device, Flo Trac/VigileoTM (Edwards Lifesciences, Irvine, CA, USA) in the last two years in medical and cardiac surgical patients requiring continuous CO monitoring during ICU stay. In our experience VigileoTM and thermodilution method show no significant differences in CO measurements in patients with ventricular dysfunction without valve disease. We think that the different experience Mayer and collegues report is due to several reasons. First, the authors included many patients (about 50% of study group) with mitral and aortic insufficiency, whose arterial compliance and impedance are of course different from patients without valve regurgitation. These differences lead to relevant changes in arterial waveform characteristics and in ventriculo-arterial coupling, which well explain the bias between VigileoTM technology and thermodilution described by Mayer. Second, they did not exclude the presence of tricuspid insufficiency in their study group, even in patients with mitral disease, so accepting a potential pittfall in thermodilution measurements. In our opinion Flo Trac sensor and pulmonary artery thermodilution catheter have different indications due to the different information they can provide. In severely hemodynamically compromised patients we agree that pulmonary thermodilution catheter remains the best option for monitoring CO and cavitary pressures. Whereas in less compromised patients, requiring flow monitoring, in our experience the new device VigileoTM provides a valuable set of information, with reliable CO calculation by Flo Trac sensor plus ScO2 measurement if the Presep central venous oximetry catheter (Edwards Lifesciences, Irvine, CA, USA) is added, with the great advantage of less invasiveness in comparison to pulmonary artery catheterization. 1) 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(2):176-82. Conflict of Interest:None declared |
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