Noninvasive and Simple Assessment of Cardiac Output and Pulmonary Vascular Resistance With Whole-Body Impedance Cardiography Is Useful for Monitoring Patients With Pulmonary Hypertension.

Taniguchi Y, Emoto N, Miyagawa K, Nakayama K, Kinutani H, Tanaka H, Shinke T, Hirata KI.

  • Background: Right heart catheterization (RHC) is the gold standard for the diagnosis of pulmonary hypertension (PH) and a useful tool for monitoring PH. However, there are some disadvantages in the regular use of RHC because it is invasive. Noninvasive methods for monitoring hemodynamics are needed to manage patients with PH. In this study, we aimed to evaluate the reliability of noninvasive hemodynamic assessment with whole-body impedance cardiography (Non-Invasive Cardiac System [NICaS]) for PH.
  • Methods and Results: We investigated 65 consecutive patients undergoing RHC. Two-thirds of them had pulmonary arterial hypertension and one-third had chronic thromboembolic PH; 25% of the patients were receiving medical therapy. Cardiac output (CO) was estimated by NICaS (NI-CO), thermodilution (TD-CO), and the Fick method (Fick-CO). There was a strong correlation between NI-CO and TD-CO (r=0.715, P<0.0001) and Fick-CO (r=0.653, P<0.0001). Noninvasive pulmonary vascular resistance (PVR) was estimated using a conventional invasive equation with NI-CO, mean pulmonary arterial pressure was calculated by echocardiographic measurement, and pulmonary capillary wedge pressure was estimated at 10mmHg in all cases. NICaS-derived PVR was very strongly correlated with invasive PVR (TD-PVR: r=0.704, P<0.0001; Fick-PVR: r=0.702, P<0.0001).
  • Conclusions: Noninvasive measurement of CO and PVR using NICaS and echocardiography is a useful tool for the assessment of PH.
 Non invasive measurements of Cardiac Output (CO) and Cardiac Power Index (CPI) by whole body bio impedance in patients with heart failure. A report from SICA- HF study (FP7/2007-2013/241558)

P Pellicori1, E Wright1, P Costanzo1, S Smith1, S Rimmer1, J Hobkirk1, A Torabi1, T Mabote1, J Warden1, JGF Cleland11University of Hull, Department of Academic Cardiology - Hull - United Kingdom,
  • Objectives: Haemodynamic dysfunction is often used as part of the definition for heart failure (HF), predicts an adverse outcome and could be an important target for therapy but is rarely measured in routine practice, perhaps because simple, effective, inexpensive technology is lacking. We assessed the ability of whole body electrical bioimpedance to measure haemodynamics non-invasively.
  • Methods: Patients and controls enrolled in the Studies Investigating Co-morbidities Aggravating Heart Failure (SICA) were included in this analysis if in sinus rhythm. Stroke volume (SV), cardiac output (CO), cardiac power index (CPI) and total body water (TBW) were measured non-invasively using whole body bio-impedance (NICaS) after two minutes rest in the supine position. Results were compared amongst HF patients according to tercile of amino-terminal pro-brain natriuretic peptide (NT-proBNP) and left ventricular ejection fraction (LVEF).
  • Results: The median age of the 51 patients with HF was 71 years (IQR:63--77), 15 were women (29%), median LVEF was 36% (IQR:29-44) and median body mass index (BMI) was 30kg/m2 (IQR:26-33). The median age of 15 control subjects was 66 years (IQR:56-75), 4 were women (27%) and median BMI was 29kg/m2(IQR:26-37). As expected, compared with controls, patients with HF had higher plasma NTproBNP, worse renal function, lower CPI (0.64±0.25w/m2 vs. 0.47±0.18w/m2;p< 0.01) but TBW was similar (47±9% vs. 46±8%;p=0.74).
  • Patients were divided into terciles of NTproBNP (lower and upper limits of the mid-tercile were 373 and 1063ng/L). Patients in the highest tercile of NTproBNP had lower BMI (32±5kg/m2 vs. 29±5kg/m2 vs.28±4kg/m2 respectively ; p=0.02), LVEF (42±5% vs. 37±9% vs. 29±8%; p<0.01), CPI (0.52±0.2w/m2 vs. 0.50±0.2w/m2vs. 0.38±0.1w/m2; p=0.04) and poorer renal function (Creatinine: 91±28μmol/l vs. 113±35μmol/l vs. 130±47μmol/l; p=0.02) and increased TBW (41±6% vs. 47±7% vs. 48±9%;p=0.02). No differences in CO or SV were found. In the lowest tercile of LVEF, SV (83±24ml vs. 67±23ml vs.58±9ml;p<0.01), CO (5.7±1.9l/min vs. 4.3±1.6l/min vs. 3.9±0.8l/min; p <0.01) and CPI (0.58±0.2W/m2 vs. 0.45± 0.2W/m2 vs. 0.38±0.1W/m2; p<0.01) were all significantly lower, but TBW was similar across terciles (43±6% vs. 46±7% vs. 48±9%; p= 0.28).
  • Conclusion: In patients with HF and sinus rhythm, whole body bio-impedance might be a useful method of monitoring the haemodynamic severity of heart failure that is quick, simple and inexpensive. Whether it is as or more useful than NTproBNP as a marker of outcome awaits the results of large long-term studies. (European Journal of Heart Failure Supplements ( 2012 ) 11 ( S1 ), S91)

Detection of left ventricular systolic dysfunction using a newly developed, laptop based, impedance cardiographic index

Yoseph Rozenman, Renee Rotzak, Robert P. Patterson


Whole Body Bioimpedance Monitoring for Outpatient Chronic Heart Failure Follow up

Yusuke Tanino, MD; Junya Shite, MD; Oscar L Paredes, MD; Toshiro Shinke, MD;
Daisuke Ogasawara, MD; Takahiro Sawada, MD; Hiroyuki Kawamori, MD;
Naoki Miyoshi, MD; Hiroki Kato, MD; Naoki Yoshino, MD; Ken-ichi Hirata, MD

  • Background: Although cardiac output index (CI), stroke volume index (SVI), and total systemic vascular resistance (TSVR) are important hemodynamic parameters for the prognosis of chronic heart failure (CHF), they are difficult to measure in an outpatient setting. Whole body bioimpedance monitoring using a Non-Invasive Cardiac System (NICaS) allows for easy, non-invasive estimation of these parameters. Here, whether NICaS-derived hemodynamic parameters are clinically significant was investigated by relating them to other conventional cardiovascular functional indices, and by evaluating their predictive accuracy for CHF readmission.
  • Methods and Results: Study subjects of 68 patients with CHF were enrolled in the study immediately upon discharge from the hospital. NICaS-derived CI, -SVI, and -TSVR values obtained at an outpatient clinic were significantly related with left ventricular ejection fraction (LVEF) measured by echocardiography, serum B-type natriuretic peptide (BNP), and exercise tolerance. During the 100±98 days follow-up, 15 patients were readmitted to our hospital for CHF recurrence. Multivariate analysis indicated that LVEF, NICaS-derived CI, NICaS-derived SVI, and plasma BNP were significant indicators (receiver operating characteristic curve cut-off point, LVEF: 37%, NICaS-derived CI: 2.49 L · min-1 · m-2, NICaS-derived SVI: 27.2 ml/m2, plasma BNP: 344 pg/ml) for readmission.
  • Conclusions: Hemodynamic parameters derived by NICaS are applicable for the non-invasive assessment of cardiac function in outpatient CHF follow up. (Circ J 2009; 73: 1074 - 1079)

The Granov Factor e A New, Effective Impedance Algorithm for Non-Invasive Ambulatory Assessment of Preclinical Congestive Heart Failure

Daniel A. Goor, Renee Rotzak, Igor Granov, Yoseph Rozenman;

  • Introduction: There are two synonymous clinical titles for the onset of left ventricular systolic dysfunction (LVSD), which is the first stage in the evolution of congestive heart failure (CHF). According to the ACC/AHA, the term is Stage B Heart Failure (HF), and it is defined as a ‘‘structural disorder of the heart, which has never developed symptoms of HF''. The Framingham Study uses the term Asymptomatic Left Ventricular Systolic Dysfunction (ALVSD), and defines it as the phase of 40e45% O ejection fraction (EF) !55%. The average prevalence of ALVSD in the adult population is approximately 5%. Hypothesis: Since the diagnosis and management of LVSD in its asymptomatic phase may halt its deterioration to the fateful CHF for years, we assume that the availability of a portable apparatus for diagnosing ALVSD in the community population will dramatically change the fate of CHF.
  • Methods: A medical instrument which consists of an ordinary laptop computer in which the CD-ROM has been replaced by an impedance device called NICaS (Non-Invasive Cardiac System) has already been described elsewhere. Recently, a new algorithm, called the Granov Factor, which is based on the systolic time intervals (STI), was specifically developed for detection of ALVSD by the NICaS. One hundred patients underwent a Helsinki approved determination of EF !55% by echocardiography and a study by the NICaS for determining GF !10.0 within two-hour intervals, at the Wolfson Hospital, Israel.
  • Results: EF !55% was found by echo in 21 patients, and comparison of the NICaS versus Echo results revealed two false negative and one false positive NICaS findings. This is a sensitivity of 90.48%, specificity of 98.63%, and positive and negative predictive values of 95.0% and 97.5%, respectively.
  • Conclusions: We introduce here an ideal portable diagnostic tool which can be used by any doctor anywhere, for the incidental diagnosis of ALVSD either during an ordinary physical examination, or through screening the community population.

Impedance Cardiography for Cardiac Output Estimation Reliability of Wrist-to-Ankle Electrode Configuration

Oscar Luis Paredes, MD; Junya Shite, MD; Toshiro Shinke, MD; Satoshi Watanabe, MD; Hiromasa Otake, MD; Daisuke Matsumoto, MD; Yusuke Imuro, MD; Daisuke Ogasawara, MD; Takahiro Sawada, MD; Mitsuhiro Yokoyama, MD

  • Background Non-invasive measurement of cardiac output (CO) may become an important modality for the treatment of heart failure. Among the several methods proposed, impedance cardiography (ICG) has gained particular attention. There are 2 basic technologies of ICG: thoracic and whole-body ICG whereby the electrodes are applied either to the chest or to the limbs. The present study is aimed to test the effectiveness of the Non-Invasive Cardiac System (NICaS), a new ICG device working with a wrist-to-ankle configuration.
  • Methods and Results: To evaluate the reliability of NICaS derived CO (NI-CO), 50 CO measurements were taken simultaneously with thermodilution (TD-CO) and modified Fick (Fick-CO) in 35 cardiac patients, with the TD-CO serving as the gold-standard for the evaluation. Overall, 2-tailed Pearson's correlation and Bland-Altman limits of agreement between NI-CO and TD-CO were r=0.91 and -1.06 and 0.68 L/min and between Fick-CO and TD-CO, r=0.80 and -1.52 and 0.88 L/min, respectively. Good correlation was observed in patients with loading conditions altered by nitroglycerin and also in patients with moderate valvular diseases.
  • Conclusion: Agreement between NI-CO and TD-CO is within the boundaries of the FDA guidelines of bioequivalence. NI-CO is applicable for non-invasive assessment of cardiac function. (Circ J 2006; 70: 1164-1168)

Impedance cardiography revisited.

Cotter G, Schachner A, Sasson L, Dekel H, Moshkovitz Y.

  • Previously reported comparisons between cardiac output (CO) results in patients with cardiac conditions measured by thoracic impedance cardiography (TIC) versus thermodilution (TD) reveal upper and lower limits of agreement with two standard deviations (2SD) of approximately +/-2.2 l min(-1), a 44% disparity between the two technologies. We show here that if the electrodes are placed on one wrist and on a contralateral ankle instead of on the chest, a configuration designated as regional impedance cardiography (RIC), the 2SD limit of agreement between RIC and TD is +/-1.0 l min(-1), approximately 20% disparity between the two methods. To compare the performances of the TIC and RIC algorithms, the raw data of peripheral impedance changes yielded by RIC in 43 cardiac patients were used here for software processing and calculating the CO with the TIC algorithm. The 2SD between the TIC and TD was +/-1.7 l min(-1), and after annexing the correcting factors of the RIC formula to the TIC formula, the disparity between TIC and TD further declined to +/-1.25 l min(-1).
  • CONCLUSIONS: (1) in cardiac conditions, the RIC technology is twice as accurate as TIC; (2) the advantage of RIC is the use of peripheral rather than thoracic impedance signals, supported by correcting factors.(Physiol Meas. 2006 Sep;27(9):817-27.)

Peripheral versus Thoracic Impedance Cardiography

Daniel A Goor, MD, Efim Frinerman, MD, Igor Granov, BSc and Robert Patterson, PhD

  • Background: Following are the two basic technologies for measuring cardiac output (CO) by impedance cardiography (ICG): Thoracic ICG (TIC) with thoracic electrodes, and peripheral ICG, where the electrodes are placed either on two limbs, called regional ICG (RIC), or on four limbs, called whole-body ICG (ICGWB). Two types of algorithms exist to calculate stroke volume. In RIC, the systolic electrical impedance change, the dR/R, is generated by the volumetric expansion of the systemic arterial tree. In TIC, however, the systolic impedance change, the dZ/dt x T, is born by the impact that cyclic changes of the blood velocity rate have on its electrical resistivity.
  • Methods & Results: Raw data of 46 RIC studies in cardiac patients were used to compare performance of the two above mentioned algorithms in calculating SV in the same patients, versus their thermodilution (TD) results. To compare the reliability of the peripheral versus the thoracic signals, data were also retrieved from the literature. The limit of agreement between TIC and TD is 2SD+2.2 lit/min, and with an average CO of 5.0 lit/min this means a 44% disparity. The combination of the peripheral signal with the TIC dZ/dt x T algorithm produced a disparity between ICG and TD of only 34%, indicating a higher reliability of the peripheral versus the thoracic impedance signal. The limits of agreement between the combined volumetric dR/R algorithm of RIC and the peripheral signal versus TD was 2SD+1.0 lit/min, which is a 20% disparity. This value is in close proximity to the FDA standard of bioequivalence, and is twice as accurate as the TIC. However, in well-defined clinical and hemodynamic conditions which will be disclosed in the presentation, the ombination of the peripheral signal with the common TIC equation involving dZ/dt x T performs better than the RIC equation involving dR/R.
  • Conclusions: 1) The peripheral impedance signal is more reliable than the thoracic signal; 2) Calculation of the peripheral SV by the RIC algorithm is more accurate than the TIC algorithm, excepting for well-defined conditions, where the dZ/dt x T performs better. (Journal of Cardiac Failure Vol. 12, Issue 6, Supplement, Pages S54-S55)
 Non-invasive measurement of cardiac output by whole-body bio-impedance during dobutamine stress echocardiography: clinical implications in patients with left ventricular dysfunction and ischaemia.

Leitman M,Sucher E, Kaluski E,Wolf R,Peleg E,Moshkovitz Y,Milo-Cotter O,Vered Z,Cotter G.

  • To compare non-invasive determination of cardiac index (CI) by whole body electrical bioimpedance using the NICaS apparatus and Doppler echocardiography, and the role of cardiac power index (Cpi) and total peripheral resistance index (TPRi) calculation during dobutamine stress echocardiography (DSE).
  • SUBJECTS AND METHODS:We enrolled 60 consecutive patients undergoing DSE. Patients were prospectively divided into 3 groups: Group 1 (n = 20): normal DSE (control). Group 2 (n = 20): EF<40% without significant ischaemia. Group 3 (n = 20): patients with significant ischaemia on DSE. Measurements of CI were performed at the end of each stage of DSE by both echocardiographic left ventricular outflow track flow and the NICaS apparatus, using whole-body bio-impedance. MAP was measured simultaneously and TPRi and Cpi were calculated.
  • RESULTS: The correlation between non-invasive CI as determined by NICaS and echocardiography was 0.81, although Echocardiographic readings of CI were higher during administration of higher doses of dobutamine. Lower EF correlated with lower Cpi, especially stress induced Cpi. Hence, patients with reduced EF (group 2) had a blunted increase in Cpi during stress. Patients with ischaemia (group 3) had a blunted increase in Cpi as well as a decrease in Cpi and increase in TPRi during the last stages of DSE.
  • CONCLUSION:Measurement of CI by NICaS correlated well with Doppler derived CI. The calculation of Cpi and TPRi changes during dobutamine stress may provide important clinical information.(Eur J Heart Fail. 2006 Mar;8(2):136-40. Epub 2005 Sep 29)

Accurate, Noninvasive Continuous Monitoring of Cardiac Output by Whole-Body Electrical Bioimpedance*

Gad Cotter, MD; Yaron Moshkovitz, MD; Edo Kaluski, MD; Amram J. Cohen, MD, FCCP; Hilton Miller, MD†; Daniel Goor, MD; and Zvi Vered, MD

  • Study objectives: Cardiac output (CO) is measured but sparingly due to limitations in its measurement technique (ie, right-heart catheterization). Yet, in recent years it has been suggested that CO may be of value in the diagnosis, risk stratification, and treatment titration of cardiac patients, especially those with congestive heart failure (CHF). We examine the use of a new noninvasive, continuous whole-body bioimpedance system (NICaS; NI Medical; Hod-Hasharon, Israel) for measuring CO. The aim of the present study was to test the validity of this noninvasive cardiac output system/monitor (NICO) in a cohort of cardiac patients.
  • Design: Prospective, double-blind comparison of the NICO and thermodilution CO determinations.
  • Patients: We enrolled 122 patients in three different groups: during cardiac catheterization (n  40);before, during, and after coronary bypass surgery (n  51); and while being treated for acute congestive heart failure (CHF) exacerbation (n  31).
  • Measurements and intervention: In all patients, CO measurements were obtained by two independent blinded operators. CO was measured by both techniques three times, and an average was determined for each time point. CO was measured at one time point in patients undergoing coronary catheterization; before, during, and after bypass surgery in patients undergoing coronary bypass surgery; and before and during vasodilator treatment in patients treated for acute heart failure.
  • Results: Overall, 418 paired CO measurements were obtained. The overall correlation between the NICO cardiac index (CI) and the thermodilution CI was r  0.886, with a small bias (0.0009  0.684 L) [mean  2 SD], and this finding was consistent within each group of patients. Thermodilution readings were 15% higher than NICO when CI was < 1.5 L/min/m2, and 5% lower than NICO when CI was > 3 L/min/m2. The NICO has also accurately detected CI changes during coronary bypass operation and vasodilator administration for acute CHF.
  • Conclusion: The results of the present study indicate that whole-body bioimpedance CO measurements obtained by the NICO are accurate in rapid, noninvasive measurement and the follow-up of CO in a wide range of cardiac clinical situations. (CHEST 2004; 125:1431-1440)

The role of cardiac power and systemic vascular resistance in the pathophysiology and diagnosis of patients with acute congestive heart failure

Gad Cotter, Yaron Moshkovitz, Edo Kaluski, Olga Milo, Ylia Nobikov, Adam Schneeweiss, Ricardo Krakover, Zvi Vered

  • Objective: Conventional hemodynamic indexes (cardiac index (CI), and pulmonary capillary wedge pressure) are of limited value in the diagnosis and treatment of patients with acute congestive heart failure (CHF). Patients and methods: We measured CI, wedge pressure, right atrial pressure (RAP) and mean arterial blood pressure (MAP) in 89 consecutive patients admitted due to acute CHF (exacerbated systolic CHF, n=56; hypertensive crisis, n=5; pulmonary edema, n=11; and cardiogenic shock, n=17) and in two control groups. The two control groups were 11 patients with septic shock and 20 healthy volunteers. Systemic vascular resistance index (SVRi) was calculated as    SVRi=(MAP-RAP)/CI. Cardiac contractility was estimated by the cardiac power index (Cpi), calculated as CIxMAP.
  • Results and discussion: We found that CI<2.7 l/min/mand wedge pressure >12 mmHg are found consistently in patients with acute CHF. However, these measures often overlapped in patients with different acute CHF syndromes, while Cpi and SVRi permitted more accurate differentiation. Cpi was low in patients with exacerbated systolic CHF and extremely low in patients with cardiogenic shock, while SVRi was increased in patients with exacerbated systolic CHF and extremely high in patients with pulmonary edema. By using a two-dimensional presentation of Cpi vs. SVRi we found that these clinical syndromes can be accurately characterized hemodynamically. The paired measurements of each clinical group segregated into a specific region on the Cpi vs SVRi diagnostic graph, that could be mathematically defined by a statistically significant line (Lambda=0.95). Therefore, measurement of SVRi and Cpi and their two-dimensional graphic representation enables accurate hemodynamic diagnosis and follow-up of individual patients with acute CHF.  (Euro J of Heart Failure 5 (2003) 443-451)

Whole-Body Electrical Bio-Impendance is accurate in Non Invasive Determination of Cardiac Output: A Thermodilution controlled, Prospective, Double Blind Evaluation.

Guillermo Torre-Amiot MD, Gad Cotter MD, Zvi Vered MD, Edo Kaluski MD, Karl Stang MD.

  • Background: The NICaSTM is a novel non-invasive apparatus based on whole body electrical bio-impedance for simple non-invasive continuous CO determination.
  • Patients and Methods: Patients were recruited while randomized in a study evaluating the efficacy of Tezosentan (a ET-A/B endothelin antagonist) in patients admitted due to acute heart failure (CHF). Patients were randomized after having been hospitalized due to acute heart failure with dyspnea at rest, CI < 2.5 L/min/m2 and PCWP ≥ 20 mmHg. Study Protocol: At baseline and during treatment with study drug at the pre-specified time points of 0.5,1,2,3,4 and 6 hours from randomization CO was determined by both thermodilution and the NICaSTM 2001 apparatus. At each time point CO was determined by thermodilution and NICaSTM 2001 apparatus by a two independed, blinded operators.
  • Results: Out of 130 patients enrolled, in 93 CO was measured simultaneously by both methods at all the pre-determined time points. The overall Correlation between the two methods was R=0.81 (Figure). Precision and bias were 0.010.6 L/min. There was a difference between the two methods in cardiac output readings. When Mean CI (of both methods) was < 2 L/min/M2 CO readings were statistically significantly lower by NICaS while when CI was >3 L/min/M2, CO readings were statistically significantly higher by NICaS. We have calculated the cardiac power index (Cpi=CI* mean arterial pressure), and found that low Cpi (indicating reduced myocardial contractile reserve) was related to higher recurrent CHF. However, Cpi based no NICaS CI measurement (NICaS Cpi) was a better predictor of recurrent CHF then thermodilution Cpi (Th Cpi), due to less accurate prediction in patients with high Cpi.
  • Conclusions: NICaS is a novel accurate non-invasive method for CO determination. The results of the present study suggest that NICaS might be more accurate then thermodilution for CO determination due to the tendency of thermodilution to underestimate CO we high and overestimate it when low.

Cardiac output-based versus empirically programmed AV interval - how different are they?

E. Crystal and I. Eli Ovsyshcher

  • Aims: To compare empirically programmed and cardiac output-based programming of atrioventricular (AV) interval in patients with dual chamber pacemakers.
  • Methods and Results: In 19 patients with implanted dual chamber pacemakers due to AV block but otherwise normal hearts, cardiac output was assessed using an impedance cardiography device. In all patients, the AV interval had been previously programmed empirically by an experienced cardiologist. Cardiac output was estimated at AV intervals from 50 to 250 ms during VDD pacing. AV intervals adjusted by serial cardiac output estimations caused a rise in cardiac output in 84% of patients. The maximal achievable cardiac output was greater by 12%&8% (range 0-32%), P<0·001, than was observed with empirically programmed AV intervals.
  • Conclusions: In patients with dual chamber pacemakers due to AV block and otherwise normal hearts, empirically selected AV intervals may lead to compromise of cardiac haemodynamics. Optimal AV intervals may be selected by serial cardiac output measurements. (Europace 1999; 1: 121-125)

Non-invasive measurement of cardiac output during coronary artery bypass grafting

Amram J. Cohen, Dimitri Arnaudov, Deeb Zabeeda, Lex Schultheis, John Lashinger, Arie Schachner.

  • Objective: A new device, using whole body bioresistance measurements and a new equation for calculating stroke volume has been developed. Using this equation, an attempt was made to correlate whole body bioresistance cardiac output with thermodilution cardiac output in patients undergoing coronary artery bypass grafting.
  • Methods: Thirty-one adults undergoing elective coronary artery bypass grafting were studied prospectively. Simultaneous paired cardiac output measurements by whole body bioresistance and thermodilution were made at five time points during coronary artery bypass grafting: in anesthetized patients before incision (T1), after sternotomy (T2), after opening the pericardium (T3), ten min post bypass (T4), and in the intensive care unit (T5). The patients had a mean of three thermodilution cardiac outputs compared with a mean of three bioimpedance measurements at each time point. The bias and precision between the methods were calculated.
  • Results: There was good correlation between bioresistance cardiac output (nCO) and thermodilution cardiac output (ThCO) measurements in both groups for all recorded times. The patients' mean ThCO and nCO, as well as bias and precision between methods were calculated. Mean ThCO ranged between 4.14 and 5.06 l/min; mean nCO ranged between 4.12 and 4.97 l/min. Bias calculations ranged between -0.072 and 0.104 l/min. Precision (2 SD) calculations ranged between 0.873 and 1.228 l/min for 95% confidence intervals. Pearson's correlation ranged from 0.919 to 0.938.
  • Conclusions: Cardiac output measured with the new device correlates well with the thermodilution measurements of cardiac output during and immediately following coronary artery bypass grafting. The overall agreement between the two methods was good. The new device is an accurate non-invasive method of measuring cardiac output during coronary artery bypass grafting. (Euro J of Cardio-thoracic Surgery 14 (1998) 64-69)