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PubMed1976

Determinants of variation between Fick and indicator dilution estimates of cardiac output during diagnostic catheterization. Fick vs. dye cardiac outputs.

Simultaneous Fick and duplicate dye cardiac outputs were done in 105 patients with various cardiovascular diseases during routine cardiac catheterization. Dye was injected into the pulmonary artery and sampled from the brachial artery. Nineteen patients had mitral and/or aortic valvular regurgitation. Eighty-four per cent of the duplicate dye cardiac outputs agreed within 10 per cent variation from the line of identity, and 98 per cent were within 25 per cent. There was no systematic difference between the Fick and dye methods. Seventy-five per cent agree within 20 per cent variation from the line of identity. However, individual variation ranged from -27 to +58 per cent. There was, also, no systematic difference between Fick and dye methods either with low cardiac index or valvular regurgitation. Variation between the two methods was less with low cardiac index and greater with higher cardiac index. The variation was not increased in the presence of valvular regurgitation. The variation in the two methods could partly be explained by errors in the measurement of arteriovenous oxygen difference and oxygen consumption. When the injection is made into the pulmonary artery and sampled from the brachial artery, dye outputs are valid irrespective of the level of resting cardiac index and valvular regurgitation as long as there are enough points to draw a straight line from semilogarithmic trace of the descending limb.

Cardiac Catheterization↗
PubMed2001

Continuous cardiac output measurements do not agree with conventional bolus thermodilution cardiac output determination.

PURPOSE: To evaluate the performance of two different continuous cardiac output monitoring systems based on the thermodilution principle in critically ill patients. METHODS: Nineteen cardiac surgical patients were randomly assigned to continuous cardiac output monitoring using one of the two systems under study (group I, IntelliCath(TM) catheter, n=9; group II, Opti-Q(TM) catheter, n=10). Each patient was studied over a period of three hours. Conventional bolus thermodilution cardiac output measurements were carried out every 15 min leading to 13 measurements in each patient. The continuous cardiac output values were compared with the bolus thermodilution measurements. Bias (mean difference between continuous and bolus thermodilution) and precision (SD of differences) were calculated as a measure of agreement between the respective continuous method and conventional bolus thermodilution. RESULTS: The range of measured cardiac outputs was 3.8-15.4 L*min(-1) (IntelliCath(TM)) and 3.5-8.3 L*min(-1) (OptiQ(TM)). Bias and precision was 0.06 +/- 0.76 L*min(-1) (IntelliCath(TM)) and -0.04 +/- 0.74 L*min(-1) (OptiQ(TM)), respectively. There was no difference in bias between the two systems (P=0.38). +/- 2 SD of the differences (i.e., 95% of the differences) did not fall within the predetermined limits of agreement of +/- 0.5 L*min(-1). CONCLUSIONS: There was no difference between the two systems regarding the agreement with conventional bolus thermodilution as the standard. A discrepancy between bolus and continuous thermodilution cardiac output measurement techniques above the clinically acceptable limits suggest that they are not interchangeable.

Adult↗
PubMed1996

Continuous venovenous haemofiltration in neonates with renal insufficiency resulting from low cardiac output syndrome after cardiac surgery.

Acute renal insufficiency is a common complication after surgery for congenital cardiovascular defects in neonates and is associated with a high incidence of morbidity and mortality. The authors reviewed their experience with continuous venovenous haemofiltration in neonates and infants with acute renal insufficiency resulting from low cardiac output following cardiovascular surgery. Twelve critically ill patients with pharmacologically intractable fluid overload were treated with continuous venovenous haemofiltration over a period of 42 months. All patients were mechanically ventilated and dependent on high doses of catecholamines. Continuous venovenous haemofiltration was started 64.2(28.2) h postoperatively and maintained for a period of 8 to 195 h. A negative fluid balance was achieved in all patients (2.1(0.5) ml/kg per h). No complications relating to continuous venovenous haemofiltration were evident during the treatment. The survival rate was 59% (seven of 12). Continuous venovenous haemofiltration is a valid and simple method for controlling fluid overload in neonates and infants with low cardiac output.

Acute Kidney Injury↗
PubMed1983

A comparison of methods of cardiac output measurement.

Cardiac output measurements determined by dye dilution, iced-injectate thermodilution and room temperature thermodilution were compared in man in order to assess the random error of each method and to examine the systematic error of both thermodilution methods in comparison with dye dilution. Results showed that random error was greatest with room temperature thermodilution and least using iced thermodilution. Iced thermodilution correlated well with dye dilution, tending to overestimate cardiac output only at low flows. Room temperature thermodilution, however, overestimated cardiac output by up to 25% in the clinically important range and more so at low cardiac output.

Cardiac Output↗
PubMed1998

Intra-operative evaluation of a continuous versus intermittent bolus thermodilution technique of cardiac output measurement in cardiac surgical patients.

The purpose of this study was to analyse the clinical agreement between cardiac output measurements, obtained using a newly available continuous thermodilution technique, and the conventional intermittent bolus technique. Twenty-four cardiac surgical patients were intra-operatively monitored using both techniques. Additionally, two different averaging modes for the continuous thermodilution technique, either the previous 6 min (group 1) or 3 min (group 2) were compared. The mean difference between the continuous thermodilution technique and the intermittent bolus technique (bias), were calculated at eight selected time points. These ranged from -0.09 to 0.42 litres min-1 in group 1 and from -0.02 to 0.18 litres min-1 in group 2. There were significant differences at any time point between the groups. The relative error between continuous thermodilution and intermittent bolus techniques was < 15% for the majority of measurements and was significantly higher in group 1 compared with group 2 just prior to cardiopulmonary bypass. Thus, the continuous thermodilution technique produced a clinically acceptable level of accuracy compared with the intermittent bolus technique measurements, especially when using an averaging mode for the previous 3 min.

Aged↗
PubMed2006

Nesiritide for treatment of perioperative low cardiac output syndromes in cardiac surgical patients: an initial experience.

The physiologic properties of the b-type natriuretic peptide nesiritide include pulmonary, coronary, and renal arterial vasodilation and lusitropic effects on ventricular myocardium. These effects may be useful during cardiac surgery, particularly when myocardial function and cardiac output (CO) are compromised. Intraoperative hemodynamic data were collected retrospectively before and 5-15 min following completion of a nesiritide loading dose in 15 adult cardiac surgical patients with low CO associated with pulmonary hypertension, low left ventricular ejection fraction, diastolic dysfunction, or left ventricular assist device placement. In seven patients, prior alternative pharmacologic interventions had failed to improve CO, and fluid challenges were ineffective in six patients with diastolic dysfunction. Perioperative nesiritide administration (2 microg.kg(-1) load, followed by 0.01 microg.kg(-1).min(-1) for a maximum of 24 h) resulted in a statistically significant median increase in CO of 35% (P = 0.0006). In conclusion, nesiritide was associated with increased CO in patients with low CO syndromes undergoing cardiac surgery, when other measures failed. This novel agent may offer an additional option to inotropes and fluid challenges for these patients perioperatively. Randomized clinical trials are desirable to determine the risks and benefits of nesiritides and to elucidate its role for the cardiac anesthesiologist.

Aged↗
PubMed1999

Static state hemodynamic variables estimation model for the moving-actuator type total artificial heart. Part. I--cardiac output estimation.

Cardiac output estimation is a very important study for the artificial heart. In this paper, we developed a cardiac output estimation model for the moving-actuator type total artificial heart (MA-TAH) that was developed at Seoul National University Hospital. The proposed model is simple and provides beat-by-beat mean cardiac output estimation. Moreover, it uses non-invasively acquired signals. Model parameters were adjusted with in vitro data by least mean square (LMS) algorithm. Results showed that the proposed scheme gives a mean estimation error of about 0.1 (l/min) for the given data. This ensures the suitability of the proposed model.

Cardiac Output↗
PubMed1999

Response time of the Opti-Q continuous cardiac output pulmonary artery catheter in the urgent mode to a step change in cardiac output.

OBJECTIVES: This study was conducted to determine the response time of the Opti-Q continuous cardiac output (CCO) device to a step change in cardiac. DESIGN: Prospective study. SETTING: University hospital animal lab. MODEL: Female sheep. INTERVENTIONS: In ten animals, cardiac output was altered suddenly by opening and closing a peripheral arteriovenous shunt to test the response time of the CCO system. MEASUREMENTS AND MAIN RESULTS: Cardiac output was measured continuously by thermodilution and ultrasonic techniques while an arteriovenous shunt was opened and closed. A total of 53 dynamic observations were made (5-6 per animal). The mean response time of the continuous cardiac output device was 86 seconds and was unaffected by the magnitude or direction of the change in cardiac output. It was also unaffected by the animal's weight. CCO values were not statistically different from standard thermodilution measurement (p = 0.895). Shunt flow ranged from 430 to 1730 ml/min and averaged 812 ml/min. The mean CCO with the shunt closed was 4.62 L/min. There was 1.5 to 2 minutes under or overshoot in cardiac output in 11% of the measurements. CONCLUSIONS: Continuous cardiac output measurement was as accurate as those made by standard bolus thermodilution. The average response time to acute changes in cardiac output was approximately 1.5 minutes or ten times faster than previously reported systems. Response time is independent of animal mass, shunt volume and the direction of cardiac output perturbations.

Animals↗
PubMed1987

Investigation of a continuous heating/cooling technique for cardiac output measurement.

Cardiac output is frequently measured to assess patient hemodynamic status in the operating room and intensive care unit. Current research for measuring cardiac output includes continuous sinusoidal heating and synchronous detection of thermal signals. This technique is limited by maximum heating element temperatures and background thermal noise. A continuous heating and cooling technique was investigated in vitro to determine if greater thermal signal magnitudes could be obtained. A fast responding thermistor was employed to measure consecutive ejected temperature plateaus in the thermal signal. A flow bath and mechanical ventricle were used to simulate the cardiovascular system. A thermoelectric module was used to apply heating and cooling energy to the flow stream. Trials encompassing a range of input power, input frequency, and flow rate were conducted. By alternating heating and cooling, thermal signal magnitude can be increased when compared to continuous heating alone. However, the increase was not sufficient to allow for recording in all patients over the expected normal range of cardiac output. Consecutive ejected temperature plateaus were also measured on the thermal signal and ejection fraction calculations were made.

Cardiac Output↗
PubMed1985

A model of ovine endotoxemia characterized by an increased cardiac output.

High cardiac output sepsis is a major clinical problem. We have designed a sheep endotoxin model to simulate this condition and have evaluated how closely it approximates the clinical situation. The animals were prepared for chronic study by the implantation of cardiopulmonary catheters. One week later, endotoxin (0.75 microgram/kg/30 min) was administered following baseline measurements, and the animals were studied for an additional 15 hr. From 6-15 hr after the administration of endotoxin, there was a statistically significant twofold increase in cardiac output. Simultaneously, the total peripheral vascular resistance and mean arterial pressure was reduced. Eicosanoid measurements made at this time indicated that the vasodilator prostanoid, prostacyclin, was not elevated. A high cardiac output (hyperdynamic) model of sepsis has thus been established by the 30 min infusion of a small quantity of endotoxin. Prostacyclin is not a mediator of this response.

Animals↗
PubMed2002

Lithium dilution measurement of cardiac output and arterial pulse waveform analysis: an indicator dilution calibrated beat-by-beat system for continuous estimation of cardiac output.

Lithium dilution cardiac output (LiDCO trade mark; LiDCO, London, UK) is a minimally invasive indicator dilution technique for the measurement of cardiac output. It was primarily developed as a simple calibration for the PulseCO trade mark (LiDCO, London, UK) continuous arterial waveform analysis monitor. The technique is quick and simple, requiring only an arterial line and central or peripheral venous access. These lines would probably already have been inserted in critical care patients. A small dose of lithium chloride is injected as an intravenous bolus, and cardiac output is derived from the dilution curve generated by a lithium-sensitive electrode attached to the arterial line. Studies in humans and animals have shown good agreement compared with results obtained with other techniques, and the efficacy of LiDCO trade mark in pediatric patients has also been proven. Compared with thermodilution, lithium dilution showed closer agreement in clinical studies with electromagnetic flow measurement.PulseCO trade mark is a beat-to-beat cardiac output monitor that calculates stroke volume from the arterial pressure waveform using an autocorrelation algorithm. The algorithm is not dependent on waveform morphology, but, rather, it calculates nominal stroke volume from a pressure-volume transform of the entire waveform. The nominal stroke volume is converted to actual stroke volume by calibration of the algorithm with LiDCO trade mark. Initial studies indicate good fidelity, and the results from centers in the United States and the United Kingdom are extremely encouraging. The PulseCO trade mark monitor incorporates software for interpretation of the hemodynamic data generated and provides a real-time analysis of arterial pressure variations (ie, stroke volume variation, pulse pressure variation, and systolic pressure variation) as theoretical guides to intravascular and cardiac filling.

Adult↗
PubMed2005

Evaluation of a lithium dilution cardiac output technique as a method for measurement of cardiac output in anesthetized cats.

OBJECTIVE: To evaluate the use of a lithium dilution cardiac output (LiDCO) technique for measurement of CO and determine the agreement between LiDCO and thermodilution CO (TDCO) values in anesthetized cats. ANIMALS: 6 mature cats. PROCEDURE: Cardiac output in isoflurane-anesthetized cats was measured via each technique. To induce different rates of CO in each cat, anesthesia was maintained at > 1.5X end-tidal minimum alveolar concentration (MAC) of isoflurane and at 1.3X end-tidal isoflurane MAC with or without administration of dobutamine (1 to 3 microg/kg/min, i.v.). At least 2 comparisons between LiDCO and TDCO values were made at each CO rate. The TDCO indicator was 1.5 mL of 5% dextrose at room temperature; with the LiDCO technique, each cat received 0.005 mmol of lithium/kg (concentration, 0.015 mmol/mL). Serum lithium concentrations were measured prior to the first and following the last CO determination. RESULTS: 35 of 47 recorded comparisons were analyzed; via linear regression analysis (LiDCO vs TDCO values), the coefficient of determination was 0.91. The mean bias (TDCO-LiDCO) was -4 mL/kg/min (limits of agreement, -35.8 to + 27.2 mL/kg/min). The concordance coefficient was 0.94. After the last CO determination, serum lithium concentration was < 0.1 mmol/L in each cat. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated a strong relationship and good agreement between LiDCO and TDCO values; the LiDCO method appears to be a practical, relatively noninvasive method for measurement of CO in anesthetized cats.

Anesthesia↗
PubMed2000

Esophageal Doppler monitor determinations of cardiac output and preload during cardiac operations.

BACKGROUND: Perioperative management of cardiac surgical patients frequently mandates measurements of cardiac output and left ventricular filling. This study compared cardiac output and left ventricular filling measured by pulmonary artery (PA) catheter and esophageal Doppler monitor (EDM). METHODS: Thirty-four patients undergoing coronary artery bypass grafting were prepared by implanting a PA catheter, an EDM, and a transit-time ultrasonic flow probe around the ascending aorta. In 20 patients, left ventricular end-diastolic short-axis area (EDA) was measured by transesophageal echocardiography. At five time points, cardiac output was measured from the flow probe, the EDM, and the PA catheter (by thermodilution), and left ventricular filling was assessed from the PA catheter (as PA diastolic pressure), the EDM (corrected flow time), and the EDA. For cardiac output, concordance correlations relating EDM to flow probe and PA catheter to flow probe were calculated, transformed (Fisher's z transformation), and compared by Student's t test. For left ventricular filling, regression coefficients were created between corrected flow time and EDA and between PA diastolic pressure and EDA. Spearman correlations were compared by Wilcoxon rank sum test. RESULTS: The EDM and the PA catheter exhibited similar relationships to the flow probe (concordance correlations, 0.55 +/- 0.35 [mean +/- standard deviation] and 0.49 +/- 0.34, respectively; p = 0.088). The correlation between corrected flow time and EDA was better than the correlation between PA diastolic pressure and EDA (concordance correlations, 0.49 +/- 0.55 versus 0.10 +/- 0.43, respectively; p < 0.01). CONCLUSIONS: These data suggest that the EDM may offer a less invasive technique for evaluating cardiac output and a more accurate estimate for preload compared with the PA catheter.

Aged↗
PubMed1979

Simple method for measurement of cardiac output by thermodilution after cardiac operation.

Cardiac output by the thermodilution technique was measured by a new No. 2 Fr. transthoracic (2F-TT) thermistor catheter placed at cardiac operation into the pulmonary artery directly through the right ventricular outflow tract. Cold (0 degree C) 5% dextrose in water (D5W) was used as indicator and injected through a percutaneously placed central venous pressure (CVP) catheter in the jugular vein. Comparison to the No. 7 Fr. Swan-Ganz (7F-SG) catheter demonstrated a close correlation (r = 0.87) and almost identical mean thermodilution cardiac output values during 530 determinations in 10 patients. No difficulty was experienced in insertion or removal of the 2F-TT catheter and no bleeding complications were noted. Experiments in six dogs showed that variation in position of the tip of the CVP catheter within the superior vena caval venous system and right atrium was not a critical factor in measurement of thermodilution cardiac output. The thermodilution cardiac output technique in general and the ease of insertion, as well as the small size of the 2F-TT catheter, should make this method especially advantageous in infants and small children.

Cardiac Output↗
PubMed2006

Mechanism of cardiac output gain from cardiac resynchronization therapy in patients with coronary artery disease or idiopathic dilated cardiomyopathy.

The mechanisms underlying cardiac resynchronization therapy have consistently been studied at rest and remain ill defined. Peak stress total isovolumic time (t-IVT) is a major determinant of cardiac output (CO) in chronic heart failure. In this study, pharmacologic stress was used to assess the effects of atrioventricular (AV) delay shortening and ventricular resynchronization elements of cardiac resynchronization therapy. Thirty patients undergoing cardiac resynchronization therapy were studied <6 months after implantation. t-IVT and CO were measured during native activation (left bundle branch block), AV delay shortening (right ventricular dual-chamber pacing), and full resynchronization (atrio-biventricular pacing). Full resynchronization shortened peak stress t-IVT by 9.4 +/- 6.2 s/min (p <0.001) and increased peak stress CO by 0.9 +/- 0.4 L/min (p <0.001), with the effects in individual patients showing a large correlation (r = -0.64, p <0.001). In contrast, simple AV delay shortening did not shorten peak stress t-IVT nor increase peak stress CO, nor was CO at rest affected by full resynchronization or AV delay shortening. Of all measurements during native activation, the best predictor of gain in peak stress CO from full resynchronization was peak stress t-IVT (r = 0.75, p <0.001), with every 5 s/min increment in peak stress t-IVT during native activation predicting a 6% gain in peak stress CO. No conventional measures during native activation at rest or during stress (including QRS duration, the Tei index, tissue Doppler intraventricular delay, and t-IVT at rest) added significant additional information. In conclusion, only during stress does resynchronization consistently increase CO. Second, little of this increment in CO is achieved by AV delay shortening alone. Third, under native activation, long t-IVT during peak stress is the single best predictor of resynchronization-mediated increment in peak stress CO.

Aged↗
PubMed1992

Induced hypothermia in the management of refractory low cardiac output states following cardiac surgery in infants and children.

Post-operative low cardiac output states remain a major cause of mortality following cardiac surgery in infants and children. Since 1979 we have used moderate induced whole-body hypothermia in the management of low-output states refractory to conventional modes of therapy. This is based not only upon the relationship between body temperature and oxygen consumption, but also on experimental work showing a beneficial effect of cooling upon myocardial contractility, particularly when there is pre-existing impairment of ventricular function. Between July 1986 and June 1990, 20 children with refractory low-output states were cooled by means of a thermostatically controlled water blanket to a rectal temperature of 32-33 degrees C. The median age was 12 months (1 week-11 years) with a median weight of 6 kg (3.5-33 kg). Ten children survived to leave hospital while a further two made a haemodynamic recovery. There was a marked reduction in heart rate (P < 0.001). The mean arterial pressure rose (P = 0.037) while there was a fall in mean atrial pressure (P < 0.001). There was a significant improvement in the urine output (P = 0.002). A fall in the platelet count (P < 0.001) was not accompanied by any change in the white cell count (P = 0.15). Although it is impossible to say whether cooling influenced the outcome in any of these children, it was usually effective in stabilising their clinical condition. The technique is simple and has a sound theoretical basis.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Output, Low↗
PubMedDate not supplied

Feasibility of preclinical cardiac output and systemic vascular resistance in HEMS in thoracic pain--the ultrasonic cardiac output monitor.

BACKGROUND: Cardiac output (CO) and systemic vascular resistance (SVR) are important hemodynamic parameters in emergency patients and for clinical early goal-directed therapy. This study evaluated the feasibility of CO and SVR determination using preclinical continuous wave Doppler ultrasound in a helicopter emergency medical service (HEMS) on emergency patients presenting with or without thoracic pain as a pilot observational study. METHODS: Forty-four consecutive medical emergency patients (62.8 +/- 22 years of age, 23 males) were classified at the scene as with (15 patients, 69 +/- 14 years of age, 40% male) or without (29 patients, 60 +/- 25 years of age, 59% male) thoracic pain by an emergency physician. Hemodynamic parameters were determined based on continuous wave Doppler noninvasively (USCOM, Sydney, Australia): stroke volume (SV), CO, cardiac index (CI), minute distance (MD), and SVR. RESULTS: Noninvasive SV, MD, CO, CI, and SVR determination is feasible using preclinical ultrasound in HEMS. Thoracic pain patients had higher SVR (2,709 +/- 891 vs 1,499 +/- 661 dyne*sec*cm-5) and lower CO/CI (3.37 +/- 1.1 vs 5.06 +/- 2.9 L/min, CI: 1.67 +/- 0.58 vs 3.18 +/- 1.34 L/min/m2) as well as a reduced aortic minute distance (11.2 +/- 3.3 m/min vs 19.1 +/- 8 m/min, P = .001) than patients without thoracic pain. Highest cardiac outputs were measured during and within 30 minutes after seizures (n = 5, 7.5 +/- 3.05 L/min). The range of CO measured in six cardiopulmonary resuscitation patients was 2.7 to 12 L/min; the level of CO was not associated with the establishing of sustained circulation. CONCLUSIONS: Determining SV, CO/CI, and SVR in different emergency situations in HEMS using rapid CW Doppler ultrasound is feasible. Thoracic pain patients have increased SVR and lower CO/CI and reduced aortic minute distance than do non-thoracic pain patients in the preclinical setting.

Aged↗
PubMedDate not supplied

Left heart assist device: early clinical experiences with management of postperfusion low cardiac output.

Low cardiac output is a continuing cause of mortality after intracardiac operation in patients coming to surgery with advanced myocardial dysfunction. A simple method using a left heart assist device (LHAD) after open heart surgery to manage low cardiac output resistant to all adjuvant therapy is described. Except for the special cannulas, all equipment necessary for the LHAD is available in any unit performing open-heart surgery. Fifteen patients who could not be separated from conventional cardiopulmonary bypass underwent postoperative support with the LHAD (up to 501 hours). Ten patients were weaned from the device and 6 were dismissed from the hospital. Four patients remain alive, the longest period after operation being 24 months. A major asset of the LHAD is that thoracic reentry is not required at termination of LHAD support, since their design permits the cannulas to remain permanently in situ. This is thought to be an important concept, since critically ill patients requiring support are precisely those in whom added risk would be imposed by a second operation.

Adult↗