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PubMed2005

Influence of different atrioventricular and interventricular delays on cardiac output during cardiac resynchronization therapy.

Restoration of the atrioventricular (AVD) and interventricular (VVD) delays increases the hemodynamic benefit conferred by biventricular (BiV) stimulation. This study compared the effects of different AVD and VVD on cardiac output (CO) during three stimulation modes: BiV-LV = left ventricle (LV) preceding right ventricle (RV) by 4 ms; BiV-RV = RV preceding LV by 4 ms; LVP = single-site LV pacing. We studied 19 patients with chronic heart failure due to ischemic or idiopathic dilated cardiomyopathy, QRS >/= 150 ms, mean LV end-diastolic diameter = 78 +/- 7 mm, and mean LV ejection fraction = 21 +/- 3%. CO was estimated by Doppler echocardiographic velocity time integral formula with sample volume placed in the LV outflow tract. Sets of sensed-AVDs (S-AVD) 90-160 ms, paced-AVDs (P-AVD) 120-160 ms, and VVDs 4-20 ms were used. BiV-RV resulted in lower CO than BiV-LV. S-AVD 120 ms and P-AVD 140 ms caused the most significant increase in CO for all three pacing modes. LVP produced a similar increase in CO as BiV stimulation; however, AV sequential pacing was associated with a nonsignificantly higher CO during LVP than with BiV stimulation. CO during BiV stimulation was the highest when LV preceded RV, and VVD ranged between 4 and 12 ms. The most negative effect on CO was observed when RV preceded LV by 4 ms. Hemodynamic improvement during BiV stimulation was dependent both on optimized AVD and VVD. LV preceding RV by 4-12 ms was the most optimal. Advancement of the RV was not beneficial in the majority of patients.

Atrial Function↗
PubMed1990

[Comparison of enoximone versus tobutamine in the treatment of low cardiac output after cardiac surgery].

Enoximone, a new cardiotonic agent not related to glycosides or catecholamines, has been suggested for treatment of low cardiac output syndromes occurring after cardiopulmonary bypass (CPB). The aim of the present study was to compare enoximone with dobutamine in the management of such cases. Twenty consecutive patients who had undergone cardiac surgery with CPB and who had a cardiac index (CI) less than 2.5 l.min-1.m-2, pulmonary capillary wedge pressure greater than 12 mmHg, and no renal failure, were randomly assigned to receive either enoximone (group E, n = 10) or dobutamine (group D, n = 10). The following parameters were monitored at baseline, 15, 30, 60, 90 min, 2, 6, 10 and 14 h: arterial, central venous, pulmonary arterial and capillary wedge pressures (PCWP), cardiac index (CI), stroke volume index (SVI), stroke work index (SWI), systemic (SVR) and pulmonary vascular resistances, as well as heart rate-pressure product (HRPP). Patients in group E were given a bolus of 0.5-1 mg.kg-1 enoximone over a 20 min period, followed by a continuous infusion of 2-20 micrograms.kg-1.min-1, depending on clinical response. In group D, patients were given 2.5 to 15 micrograms.kg-1.min-1 dobutamine according to clinical response. No other inotropic drug was used during the study period. The aim was to obtain an increase in CI greater than or equal to 30% at the end of the first hour of treatment. Excessive systemic hypotension with low SVR was treated with volume loading.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2001

Comparison of bioimpedance versus thermodilution cardiac output during cardiac surgery: evaluation of a second-generation bioimpedance device.

OBJECTIVE: To compare a second-generation thoracic electrical bioimpedance (TEB) hemodynamic monitoring system with the clinically used pulmonary artery catheter thermodilution (TD-PAC) system. DESIGN: Blinded, simultaneous measurements at specified key time points during surgery. SETTING: University teaching hospital cardiac surgical operating rooms. PARTICIPANTS: Forty-seven patients undergoing primary elective coronary artery bypass surgery. INTERVENTIONS: Timed cardiac output measurements by thermodilution and continuous monitoring of bioimpedance were performed. MEASUREMENTS AND MAIN RESULTS: Cardiac index (TEB and TD-PAC) and other hemodynamic parameters were measured at 4 time points: (1) after anesthesia induction, (2) with the mediastinum open, (3) immediately after cardiopulmonary bypass, and (4) at the end of the case. Pearson's correlation and Bland-Altman analysis were carried out. Cardiac index by TEB and TD-PAC had an overall correlation of r = 0.71 (p < 0.0001). The Bland-Altman statistics showed a mean difference of -0.28 L/min/m2 and precision of 0.67 L/min/m2. The best correlation was at time 1, and the lowest correlation was at time 4. Mediastinal opening and cardiopulmonary bypass had little or no effect on the correlation between technologies. CONCLUSION: TEB reporting of cardiac index during coronary artery surgery generally agreed with TD-PAC cardiac index except at the end of the case (time 4).

Adult↗
PubMed1990

Noninvasive versus invasive assessment of cardiac output after cardiac surgery: clinical validation.

The accuracy of noninvasive cardiac output (CO) measurement techniques, such as electrical bioimpedance (BIO), suprasternal continuous-wave Doppler (CWD), pulsed-wave Doppler (PWD), and transesophageal continuous-wave Doppler (TED) ultrasound has been variably judged in recent years. In addition, clinical comparisons are hampered by the fact that there is no generally accepted gold standard in CO measurement. After coronary artery bypass surgery in 25 patients, CO was simultaneously determined by invasive standard techniques (thermodilution [TD] and Fick methods) plus BIO, CWD, PWD, and TED. There was an excellent agreement found between TD and the Fick method (COF = 0.13 + 1.01.COTD; r = 0.96; n = 99). Thermodilution was thus chosen to be the reference method. Bioimpedance underestimated COTD (COBIO = 0.47 + 0.60.COTD; r = 0.78; n = 111). Allowing physiological ejection times only led to an improved agreement between BIO and TD (COBIO = 0.05 + 0.69.COTD; r = 0.82; n = 79), but BIO still significantly underestimated COTD (P less than 0.0005). Using physiologic ejection times during COCWD determination reduced the scatter of data as compared with TD; however, CWD still considerably overestimated COTD, when COCWD computation was based on the echocardiographic aortic diameter (ECHO) (COCWD ECHO = 0.79 + 1.40.COTD; r = 0.84; n = 52). With the surgical aortic diameter (SURG), the agreement improved (COCWD SURG = 0.75 + 1.16.COTD; r = 0.89; n = 44), but overestimation of COTD remained significant (P less than 0.05). Irrespective of the aortic diameter, COPWD values showed a considerable scatter of data compared with COTD (COPWD ECHO = 1.26 + 0.60.COTD; r = 0.62; n = 64 and COPWD SURG = 1.42 + 0.41.COTD; r = 0.47; n = 61). Correlation of absolute COTED values to thermodilution depended on the method used for calibration. All investigated noninvasive CO measurement techniques unreliably measured relative CO changes. Despite its invasiveness, TD remains the method of choice for accurate CO determination in adult patients following cardiac surgery.

Adult↗
PubMed2004

Pulmonary artery thermodilution cardiac output vs. transpulmonary thermodilution cardiac output in two patients with intrathoracic pathology.

In two adult patients, one with a severe hemorrhage and one with a partial anomalous pulmonary vein, cardiac output (CO) measurements were performed simultaneously by means of the bolus transpulmonary thermodilution technique (COao) and continuous pulmonary artery thermodilution method (CCOpa). In both cases, the methods revealed clinically significant different cardiac output values based upon the site of measurement and the underlying pathology. The assessment of cardiac output (CO) is considered an important part of cardiovascular monitoring of the critically ill patient. Cardiac output is most commonly determined intermittently by the bolus thermodilution technique with a pulmonary artery catheter (COpa). As continuous monitoring of CO is preferable to this intermittent technique, two major techniques have been proposed. Firstly, a nearly continuous thermodilution method (CCOpa) using a heating filament mounted on a pulmonary artery catheter (Baxter Edwards Laboratories, Irvine, CA), with a clinically acceptable accuracy compared with the intermittent bolus technique. Based on these results we assumed CCOpa equivalent to real CO during hemodynamically stable conditions, and secondly, a continuous cardiac output system based on pulse contour analysis (PCCO), such as the PiCCO system (Pulsion Medical System, Munchen, Germany). To calibrate this device, which uses a derivation of the algorithm of Wesseling and colleagues, an independently obtained value of CO by the transpulmonary thermodilution method (COao) is used. Clinical validation studies in patients without underlying intrathoracic pathology, comparing transpulmonary COao with the pulmonary technique (COpa), mostly yielded good agreement.

Aged↗
PubMed2003

Performance of noninvasive partial CO2 rebreathing cardiac output and continuous thermodilution cardiac output in patients undergoing aortic reconstruction surgery.

BACKGROUND: In the partial CO(2) rebreathing method, monitored changes in CO(2) elimination and end-tidal CO(2) in response to a brief rebreathing period are used to estimate cardiac output. However, dynamic changes in CO(2) production during ischemia and reperfusion may affect the accuracy of these estimates. This study was designed to compare measurements of cardiac output as produced by the partial CO(2) rebreathing (NICO), bolus (BCO), and continuous thermodilution (CCO) methods of monitoring cardiac output. METHODS: Cardiac output was continuously monitored using both NICO and CCO in 28 patients undergoing aortic reconstruction. BCO measurements were taken at the following intervals when hemodynamic stability was achieved: (1) after anesthetic induction; (2) during aortic cross-clamp; (3) at reperfusion of the iliac artery; and, (4) during peritoneal closure. RESULTS: The bias and precision (1 SD) derived from all the measurements between NICO and BCO was -0.58 +/- 0.9 l/min, whereas for CCO and BCO it was 0.38 +/- 1.17 l/min. The bias between NICO and BCO was small after anesthetic induction and during cross-clamp, but increased following reperfusion. The bias between CCO and BCO was relatively small until reperfusion but increased significantly at peritoneal closure. CONCLUSIONS: Results indicate that in aortic reconstruction surgery the performance of NICO monitoring is comparable with that of CCO; however, the direction of bias in these continuous measurement devices is the opposite.

Aged↗
PubMed1999

Agreement and clinical utility of 2 techniques for measuring cardiac output in patients with low cardiac output.

BACKGROUND: The reliability of cardiac output obtained with the bolus technique is a problem. OBJECTIVES: To compare measurements of cardiac output measured with bolus and continuous techniques in patients with low cardiac output and to determine if measurements obtained with the continuous technique increased the number of subsequent clinical decisions. METHODS: In 60 intensive care patients, a nurse recorded a single continuous cardiac output measurement and then obtained the mean of 3 consecutive bolus determinations. The medical records of these 60 patients (experimental group) for the next 48 hours and of 60 other patients with regular or mixed venous oximetry catheters (control group) were reviewed to assess the occurrence of cardiac output events and the frequency of clinical decisions based on the events. RESULTS: Mean cardiac output was 4.46 L/min by the continuous technique and 5.20 L/min by the bolus technique (P = .011) for the experimental group. Median bias between the 2 types of measurements was -0.10 L/min (P = .79). Twenty-three of the pairs (38%) had an absolute percent difference greater than 15%. Of these, 18 (78%) had a higher bolus reading. Treatment decisions per 48 hours were 9.9 for the experimental group and 8.6 for the control group (P = .014). Median length of stay was 2 days less in the experimental group (P = .02), and mean highest cardiac output was 0.81 L/min higher (P = .009). CONCLUSIONS: Measurements of cardiac output determined with the continuous technique may be more precise than measurements determined with the bolus technique. Continuous cardiac output information increases the number of treatment decisions and actions that may shorten hospital length of stay.

Cardiac Output↗
PubMed1988

Pathogenesis of sodium and water retention in high-output and low-output cardiac failure, nephrotic syndrome, cirrhosis, and pregnancy (2)

This article has analyzed the pathogenesis of sodium and water retention in several circumstances. The initiator of retention has been proposed to be either a fall in cardiac output (e.g., low-output cardiac failure and vasoconstrictor hypovolemic nephrotic syndrome) or peripheral arterial vasodilatation (e.g., high-output cardiac failure, cirrhosis, arteriovenous fistula, and pregnancy). In the only state discussed, in which the kidney is diseased and not merely responding to extrarenal reflexes--i.e., nephrotic syndrome--intrarenal mechanisms may predominate and lead to expansion of the arterial vascular tree and suppression of the renin-angiotensin-aldosterone system (i.e., hypervolemic nephrotic syndrome). Otherwise, when kidneys are healthy, either a fall in cardiac output or peripheral arterial vasodilatation may diminish arterial vascular filling and thereby initiate a series of hemodynamic and hormonal events that result in renal sodium and water retention (Fig. 7). Finally, the approach presented in this article should be considered to be a vantage point from which to evaluate states of sodium and water retention, but not to be an exclusive position.

Animals↗
PubMed2000

Noninvasive whole-body electrical bioimpedance cardiac output and invasive thermodilution cardiac output in high-risk surgical patients.

OBJECTIVE: To evaluate the reliability of whole-body impedance cardiography with two electrodes on either both wrists or one wrist and one ankle for the measurement of cardiac output compared with the thermodilution method. DESIGN: Prospective, clinical investigation SETTING: Surgical intensive care unit of a university-affiliated community hospital. PATIENTS: Simultaneous cardiac output measurements by noninvasive whole-body impedance cardiography (nCO) and invasive thermodilution (thCO) in 22 high-risk surgical patients scheduled for extended surgery requiring perioperative pulmonary artery catheter monitoring. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 109 sets of measurements consisting of 455 single comparison measurements between nCO and thCO were included in the analysis. The mean cardiac output difference between the two methods was 1.62 L/min with limits of agreement (2 SD) of +/- 4.64 L/min. The inter-measurement variance was slightly higher for nCO. The correlation coefficient between nCO and thCO was r2 = 0.061 (p < .001) for single measurements and r2 = 0.083 (p < .002) for sets of three to six measurements. The two most predictive factors for between-method differences were the absolute thCO value (r2 = 0.13; p < .001) and whether or not a continuous nitroglycerin infusion was used (p < .05, Student's t-test). CONCLUSIONS: Agreement between whole-body impedance cardiography and thermodilution in the measurement of cardiac output was unsatisfactory. Factors that can explain these differences are differences between the populations used for calibration of nCO and the study population, the influence of changing peripheral perfusion, and the effect of a supranormal hemodynamic state on the bioimpedance signal. Whole-body impedance cardiography cannot be recommended for assessing the hemodynamic state of high-risk surgical patients as studied in this investigation.

Adult↗
PubMed2001

High Output Cardiac Failure.

Congestive heart failure describes a syndrome with complex and variable symptoms and signs, including dyspnea, increased fatigability, tachypnea, tachycardia, pulmonary rales, and peripheral edema. Although this syndrome usually is associated with low cardiac output, it may occur in a number of so-called high output states, when the cardiac output is normal or greater than normal. A high output state may occur in chronic severe anemia, large arteriovenous fistula or multiple small arteriovenous shunts as in Paget's bone disease, some forms of severe hepatic or renal disorders, and acutely in septic shock. The syndrome of systemic congestion in a high output state is traditionally referred to as high output heart failure. However, the term is a misnomer because the heart in these conditions is normal, capable of generating very high cardiac output. The underlying problem in high output failure is a decrease in the systemic vascular resistance that threatens the arterial blood pressure and causes activation of neurohormones, resulting in an increase in salt and water retention by the kidney. Many of the high output states are curable conditions, and because they are associated with decreased peripheral vascular resistance, the use of vasodilator therapy for treatment of congestion may aggravate the problem. There are other clinically important issues in high output failure that have received little attention in the current medical literature. This article reviews the available data on high output cardiac failure with particular emphasis on the underlying mechanisms and treatment.

Journal Article↗
PubMed1999

Evaluation of a new continuous thermodilution cardiac output monitor in cardiac surgical patients: a prospective criterion standard study.

OBJECTIVE: To evaluate the accuracy of a new continuous cardiac output monitor in critically ill patients. DESIGN: Criterion standard study. SETTING: Cardiac surgery intensive care unit in a university hospital. PATIENTS: Twenty cardiac surgical patients requiring intensive care treatment with pulmonary artery catheters after surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Cardiac output was monitored continuously with a modified pulmonary artery catheter that has a heating filament on the outside of the catheter. Four modes of data processing with different response times ("Normal," "Fast," "FastFilter," and "Urgent" modes) used by the monitoring system. A total of 240 determinations of cardiac output were performed using conventional bolus thermodilution technique; these results were compared with those obtained using three of the four continuous measuring modes available ("Normal," "FastFilter," and "Urgent"). Cardiac output ranged from 3.47 to 15.77 L/min (bolus thermodilution). The mean (bias) +/- SD of differences (precision) for all measurements was 0.40+/-1.26 L/min in the Normal mode (cardiac output <10 L/min: 0.34+/-0.66 L/min), 0.53+/-1.27 L/min in the FastFilter-mode (cardiac output <10 L/min: 0.60+/-0.75 L/min), and 0.63+/-1.34 L/min in the Urgent mode (cardiac output <10 L/min: 0.57+/-0.82 L/min). CONCLUSIONS: Continuous cardiac output measurement using the thermodilution technique is reasonably accurate, reliable, and applicable in routine clinical practice. The values obtained using the Normal mode of the monitor agreed significantly better with the conventional thermodilution method than the results of the two other modes studied (FastFilter and Urgent). In addition, measurements in two patients with cardiac output values of >10 L/min did not agree with the results of the bolus thermodilution method.

Adult↗
PubMed2004

Effect of surgical banding of a high-flow fistula on access flow and cardiac output: intraoperative and long-term measurements.

Creation of either a natural arteriovenous graft or a fistula as a vascular access to support long-term hemodialysis can lead to "high-output" cardiac failure. The authors describe a patient who underwent surgical banding of an upper arm arteriovenous fistula. Access flow and cardiac output were measured not only pre- and postoperatively but also intraoperatively using a modified Swan Ganz catheter, originally developed to measure access flows during radiologic procedures. Banding resulted in a significant decrease in access flow and cardiac output, which was sustained for up to 1 year postoperatively.

Arteriovenous Fistula↗
PubMed1989

Effect of isosorbide dinitrate on cardiac output in severe cardiac failure: relation to initial hemodynamics, ventricular volume, and the preload reserve mechanism.

Isosorbide dinitrate (ISDN) improves the clinical and hemodynamic state of patients with heart failure, but may cause dizziness and syncope. To characterize patients in whom cardiac output falls with high-dose nitrate therapy and to examine further the pathophysiology of the fall in cardiac output in these patients, we studies the effect of sublingual ISDN on forward cardiac output in 14 patients with severe cardiac failure (New York Heart Association grades 3-4). We examined systolic and diastolic left ventricular (LV) function from pressure and volume analyses of LV function. After administration of 15 mg ISDN, cardiac output was either unaltered or increased in 7 patients (Group 1) (11 +/- 12%, mean +/- SD), and decreased in 7 (Group 2) (-13 +/- 10%) (Group 1 vs. 2, p less than 0.002). Initial systemic arterial pressure, LV ejection fraction, wedge and LV transmural filling pressures were similar in both groups, but Group 2 patients had a lower systemic vascular resistance (p = 0.07) and tended to have a larger initial LV end-diastolic volume and increased end-diastolic compliance; following ISDN the decrease in LV filling pressure and end-diastolic volume was larger and the product of the changes greater (p less than 0.02). Thus ISDN decreases filling pressure and improves forward cardiac output in some patients with congestive heart failure, but large doses may decrease cardiac output in a subset of patients who have a lower systemic vascular resistance and a larger more compliant ventricle, maintaining forward blood flow predominantly by a preload reserve mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2001

Assessment of lithium dilution cardiac output as a technique for measurement of cardiac output in dogs.

OBJECTIVES: To determine agreement of cardiac output measured by use of lithium dilution cardiac output (LiDCO) and thermodilution cardiac output (TDCO) techniques in dogs and to determine agreement of low- and high-dose LiDCO with TDCO. ANIMALS: 10 dogs (7 males, 3 females). PROCEDURE: Cardiac output was measured in anesthetized dogs by use of LiDCO and TDCO techniques. Four rates of cardiac output were induced by occlusion of the caudal vena cava, changes in depth of anesthesia, or administration of dobutamine. Lithium dilution cardiac output was performed, using 2 doses of lithium chloride (low and high dose). Each rate of cardiac output allowed 4 comparisons between LiDCO and TDCO. RESULTS: 160 comparisons were determined of which 68 were excluded. The remaining 92 comparisons had values ranging from 1.10 to 12.80 L/min. Intraclass correlation coefficient (ICC) between low-dose LiDCO and TDCO was 0.9898 and between high-dose LiDCO and TDCO was 0.9896. When all LiDCO determinations were pooled, ICC was 0.9894. For determinations of cardiac output < 5.0 L/min, ICC was 0.9730. Mean +/- SD of the differences of TDCO minus LiDCO for all measurements was -0.084+/-0.465 L/min, and mean of TDCO minus LiDCO for cardiac outputs < 5.0 L/min was -0.002+/-0.245 L/min. CONCLUSIONS AND CLINICAL RELEVANCE: The LiDCO technique is a suitable substitute for TDCO to measure cardiac output in dogs. Use of LiDCO eliminates the need for catheterization of a pulmonary artery and could increase use of cardiac output monitoring, which may improve management of cardiovascularly unstable animals.

Anesthesia↗