SEARCH · PubMed Health

Results for “CARDIAC OUTPUT”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 397 records · Page 22Linked to original sources

PubMed2003

Evaluation of a new invasive continuous cardiac output monitoring system: the truCCOMS system.

OBJECTIVE: To compare measurements of cardiac output using a new pulmonary artery catheter with those obtained using two "gold standard" methods: the periaortic transit time ultrasonic flow probe and the conventional pulmonary artery thermodilution. DESIGN: Prospective clinical trial. SETTING: Cardiac surgery operating room and surgical ICU in a university hospital. MATERIAL AND METHODS: In the operating room, a new pulmonary artery catheter (truCCOMS system) was inserted in eight patients. A periaortic flow probe was inserted in four of them. Measurements of cardiac output obtained with the truCCOMS catheter and with the flow probe were compared at different phases of the surgical procedure. In the intensive care unit, the cardiac output displayed by the truCCOMS monitor was compared with the value obtained after bolus injection performed subsequently. RESULTS: In the operating room (70 measurements), the coefficient of correlation between cardiac output measured by the flow probe and the truCCOMS system was r2 = 0.79, the bias was +0.11 l/min with a precision of 0.47 l/min, and limits of agreement -0.83 to +1.05 l/min. In the intensive care unit (108 measurements), the coefficient of correlation between cardiac output measured by thermodilution and the truCCOMS system was r2 = 0.56, the bias was -0.07 l/min, the precision was 0.66 l/min, and the limits of agreement were -1.39 to +1.25 l/min. CONCLUSION: The truCCOMS system is a reliable method of continuous cardiac output measurement in cardiac surgery patients.

Aorta↗

PubMed1989

Effect of hemoglobin concentration on critical cardiac output and oxygen transport.

We previously found limited tolerance to acute reduction in cardiac output in lambs at the nadir of their physiological anemia [Am. J. Physiol. 253 (Heart Cir. Physiol. 12): H100-H106, 1987]. To determine the effect of hemoglobin concentration [Hb] on critical cardiac output, critical systemic O2 transport, and peripheral O2 extraction, we performed 31 experiments in 12 one-mo-old lambs at four [Hb] (means +/- SD in g/dl): 7.4 +/- 0.6, 10.5 +/- 0.5, 14.5 +/- 0.5, and 16.5 +/- 0.6. Desired [Hb] was obtained by exchange transfusion with packed red cells or plasma. Cardiac output was reduced by inflation of a balloon-tipped catheter in the right atrium, and critical levels were defined at the point where O2 consumption decreased and/or arterial blood lactate concentration increased in response. With lower [Hb], cardiac output was unchanged, systemic O2 transport was reduced, and fractional O2 extraction was increased, keeping O2 consumption constant at base line. As [Hb] was reduced, critical cardiac output was significantly higher, whereas critical systemic O2 transport was independent of [Hb], as were fractional O2 extraction and mixed venous PO2 at the critical point. Thus peripheral O2 extraction was not affected by changes in [Hb] during progressive decreases in cardiac output. We conclude that 4-wk-old lambs have decreased tolerance to reductions in cardiac output and systemic O2 transport because their relative anemia provides them with a base-line cardiac output and systemic O2 transport close to the critical level.

Animals↗

PubMed1999

Determination of cardiac output by the Fick method, thermodilution, and acetylene rebreathing in pulmonary hypertension.

Assessment of cardiac output is an important part of the management of patients with pulmonary hypertension. The accuracy of the thermodilution technique in patients with low cardiac output or severe tricuspid regurgitation has been questioned. To address this issue, we simultaneously compared 105 cardiac output measurements by the Fick method and thermodilution in 35 patients with pulmonary hypertension. Moreover, we evaluated the acetylene rebreathing technique, a noninvasive method of determining cardiac output. The mean difference +/- 95% limit of agreement between thermodilution and the Fick method was +0.01 +/- 1.1 L/min. The mean difference +/- 95% limit of agreement between acetylene rebreathing and the Fick method was -0.23 +/- 1.14 L/min. Neither the mean agreement nor the 95% limits of agreement of both thermodilution and acetylene rebreathing with the Fick method were affected by the presence of low cardiac output or severe tricuspid regurgitation. We conclude that thermodilution and acetylene rebreathing are useful tools for assessing cardiac output in patients with pulmonary hypertension, even in the presence of low cardiac output or severe tricuspid regurgitation.

Acetylene↗

PubMed1991

[Diaphragmatic fatigue and its recovery are influenced by markedly decreased cardiac output: possible involvement of neuromuscular junction].

Effects of highly decreased cardiac output on the development and recovery of diaphragmatic fatigue were studied in dogs. The fatigue was induced by supramaximal electrical stimulation (20 Hz) of phrenic nerves for 30 minutes. Cardiac output was reduced during this period to 30% of control value by mechanically obstructing inferior vena cava with a balloon in animals with lowered cardiac output group (lowered Qt group). Cardiac output was maintained at normal value throughout the experiment in animals of the other group (control group). The animals were observed for recovery for 60 minutes after induction of the fatigue. The standardized transdiaphragmatic pressure (Pdi/Pdi 100) and integrated electromyographic activity (Edi/Edi 100) elicited by electrical test stimuli (20, 100 Hz) were significantly lower in lowered Qt group (P less than 0.01) during entire fatigue and recovery period. The decrease of Pdi/Pdi 100 and Edi/Edi 100 at high frequency test stimuli (100 Hz) was observed only in lowered Qt group. These results suggest that when cardiac output is severely decreased the diaphragm is more susceptible to fatigue, and that this may be caused by a failure of neuromuscular junction as well as by an impaired excitation-contraction coupling.

Animals↗

PubMed1988

Is the measurement of cardiac output useful in clinical practice?

The derivation of the "cardiac output" in man is fraught with difficulties whatever principle of measurement is used. The theories underlying the principles involved are sound; the problem arises in their application to the measurement in man. Of equal moment are the immense practical difficulties in applying the techniques available. Together these difficulties frequently give rise to unacceptable errors in the derivation of the "cardiac output". There is no "gold standard" of measurement; all methods have inherent difficulties in their application to man. If intense attention is paid to the practice of any one of the techniques available, then it is possible to reduce the variability of the measurement to acceptable proportions, but the conditions necessary to obtain such narrow ranges of variability in the human subject rarely obtain in routine clinical practice. These realizations apply to the techniques available at present, and it is difficult to imagine that there will be further development of the invasive methods available which would negate these. In contrast, it is possible that refinement of some of the non-invasive techniques now being introduced will allow reasonably reliable measurement of the cardiac output with greater facility than is possible at present. Finally, this brings into question the whole objective of the utility of measurement of cardiac output in practice. Frequently it is measured without due deference to its usefulness. Doubtless there are situations in which the measurement of cardiac output may be of scientific, if not of individual clinical benefit, for example the influence of drugs in hypertension and heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Output↗

PubMed1999

Pulmonary blood flow distribution in lobar hypoxia--influence of cardiac output and nitric oxide inhalation.

Inhaled NO is reported to be less effective in patients with ARDS if cardiac output is high (> 10 L/min). It has also been demonstrated that increased blood flow and increased shear stress cause an enhancement of endogenous NO production. In one-lung ventilation and regional hypoxia, nitric oxide (NO) delivered to the ventilated lung may decrease blood flow to the nonventilated lung and improve arterial oxygenation. So far, however, results have been divergent. The present study was performed with the hypothesis that inhaled NO would be less effective if cardiac output was increased. In the anaesthetized pig, hypoxia (5% O2) was induced in the left lower lobe. NO was delivered consecutively to the hypoxic lobe and to the other, oxygenated parts, of the lungs during continuous measurement of lobar blood flow and total lung blood flow. Bleeding and infusion of dextran caused variation in cardiac output. It was found that lobar hypoxia per se reduced lobar blood flow from 22.9+/-3.1% to 4.7+/-0.9% of cardiac output. An increase (3.2+/-0.3 L x min(-1)) and a decrease (2.2+/-0.2 L x min(-1)) in cardiac output did not alter the relative perfusion of the hypoxic lobe from baseline cardiac output (2.6+/-0.2 L x min(-1)) values. When NO was delivered to the hypoxic lobe, there was a marked increase in relative lobar perfusion to 19.0+/-2.9% during low cardiac output and 16.5+/-2.7% during high cardiac output without any significant difference between the two NO-induced increases of lobar perfusion. The increase in lobar perfusion tended to depend inversely on total pulmonary blood flow when cardiac output had been reduced by bleeding but without reaching statistical significance (r = -0.42, p > 0.05). The decrease in mean pulmonary artery pressure and PaO2 seen during NO inhalation to the hypoxic lobe did not correlate with the level of cardiac output. When NO was delivered to the oxygenated parts of the lungs, no significant effect on relative lobar perfusion or arterial oxygenation was observed, either at raised or at lowered cardiac output. The findings give no further evidence to show that variations in cardiac output alter the effect of NO inhalation.

Administration, Inhalation↗

PubMed1986

Effects of intermittent positive-pressure ventilation on cardiac output measurements by thermodilution.

Sequential thermodilution measurements of cardiac output in mechanically ventilated patients undergoing cardiac surgery demonstrated a cyclic modulation which correlated with changes in airway pressure, and was not affected by opening the pericardium. There was no satisfactory point for single measurements, which suggests that random thermodilution measurements of cardiac output during intermittent positive-pressure ventilation should be avoided, even when triplicate measurements are performed. To estimate the mean cardiac output, at least two measurements should be made at predetermined points of the ventilatory cycle. We recommend paired measurements at midinspiration and end-expiration.

Adult↗

PubMed2005

Noninvasive techniques for measurements of cardiac output.

PURPOSE OF REVIEW: Measuring stroke volume or cardiac output is of paramount importance for the management of critically ill patients in the intensive care unit, or 'high risk' surgical patients in the operating room. The new noninvasive techniques are gaining acceptance among intensivists and anesthesiologists who have been trained almost exclusively in the pulmonary artery catheter and the thermodilution technique. RECENT FINDINGS: The present review focuses on the recent publications related to esophageal Doppler, Fick principle applied to carbon dioxide associated with partial rebreathing, and pulse contour analysis. Recent validation studies have confirmed the previous findings: all three methods provide reliable estimations of cardiac output and its variations. There is not a single method standing out and ruling out the others. Many investigators are now using one of the 'noninvasive' monitors to measure cardiac output in clinical or experimental studies. SUMMARY: By making cardiac output easily measurable in various settings, these techniques should all contribute to improve hemodynamic management in critically ill or high-risk surgical patients.

Carbon Dioxide↗

PubMed1985

Pulsed Doppler determinations of cardiac output in neonates: normal standards for clinical use.

Noninvasive monitoring of cardiac output can greatly facilitate the clinical assessment and management of neonates with cardiovascular compromise. To assess normal values of cardiac output in neonates, mean blood flow velocity was measured in the ascending aorta from a suprasternal approach using a range-gated, pulsed Doppler velocity meter, and aortic root diameter was determined from an M-mode echocardiogram. These techniques were combined, and cardiac output was evaluated in 59 healthy premature and 62 term newborn infants during the first week of life. Birth weights ranged from 780 g to 4,740 g and gestational age from 27 to 42 weeks. Cardiac output values increased linearly with advancing birth weight (r = +.94, P less than 0.001) and gestational age (r = +.95, P less than .001). Mean cardiac output values (+/- SD) per kilogram of body weight were 249 +/- 34 mL/min/kg and decreased with advancing birth weight: less than 1,500 g = 265 +/- 32 mL/min/kg; 1,500 to 2,500 g = 253 +/- 34 mL/min/kg; and greater than 2,500 g = 241 +/- 33 mL/min/kg. For clinical use, 325 mL/min/kg and 200 mL/min/kg can be used as upper and lower limits of normal, respectively. Doppler cardiac output estimates compared favorably with studies using invasive techniques.

Birth Weight↗

PubMed1993

Room-temperature thermodilution cardiac output. Central venous vs side port.

OBJECTIVE: To assess the accuracy of room-temperature thermodilution cardiac output measurements from the side port (SP) of the introducer catheter through which the pulmonary artery flotation catheter is inserted. DESIGN: Central venous port (CVP) cardiac output measurements were compared with SP cardiac output measurements using the same right-heart catheter. SETTING: The general intensive care unit of the Hospital for Joint Diseases, Orthopedic Institute, New York. PATIENTS: Thirty one orthopedic patients with 31 different right-heart catheters placed in the right internal jugular or right subclavian position were evaluated. INTERVENTION: Four injections of 10 ml of normal saline solution at room temperature were made through each port; the results of the last three injections were averaged. Cardiac output determinations from both ports were completed in less than 10 min. The order of port injection was random. RESULTS: A significant difference was noted between cardiac output determinations from the two ports (p < 0.001, paired Student's t test) with the SP slightly overestimating thermodilution cardiac outputs by 6.34 +/- 8.38 percent compared to the CVP. A significant correlation was noted between both ports (r = 0.97, p < 0.001) with the linear regression line starting at the origin (y intercept not significantly different from zero) with a slope (1.07) significantly greater than 1. CONCLUSION: If the proximal CVP becomes nonfunctional, room-temperature thermodilution cardiac outputs from the SP can be used with the understanding that a slight overestimation of cardiac output will occur.

Aged↗

PubMed1983

Method for computation of cardiac output in mitral stenosis independent of left ventricular dimensions and kinetic state: correlation with cardiac catheterization via the Fick method.

An hydraulic orifice formula offering the possibility of quantifying cardiac output in conditions of mitral stenosis is tested using potentially noninvasive portions of catheterization data from patients evaluated for obstructive mitral valve disease. The equation studied is V = (1/21) R A T2, where V is the cardiac output (ml/min), R is the heart frequency, A is the mitral valve area (cm2), and T is the diastolic filling interval (sec/min). The mitral valve area was determined by the Gorlin formula, and R and T were measured from the pressure tracings recorded at cardiac catheterization. The degree of correspondence between the equation tested and the measured cardiac output as determined by the Fick principle technique is characterized by r = 0.87, SE = 450 ml/min, N = 10. The results suggest that the new formulation may offer a noninvasive method for estimating the cardiac output status of patients with mitral valve disease once mitral valve area is measured either at catheterization or by two-dimensional echocardiography.

Cardiac Catheterization↗

PubMed1991

High cardiac output as a paraneoplastic syndrome.

A high cardiac output (17 1 min-1) was recorded in a young man suffering from lymphoplasmatocytotic lymphoma. The evolution of the blood disease was characterized by two relapses, during which clinical signs of heart failure were prominent but resolved with efficient blood chemotherapy. The known aetiologies of high cardiac output were excluded. The complete normalization of the cardiac parameters with blood remission suggests that the high cardiac output represented an unusual paraneoplastic syndrome, the pathogenesis of which still remains unknown, although several hypotheses were tested.

Adult↗

PubMed1992

Regional blood flow in chronic heart failure: the reason for the lack of correlation between patients' exercise tolerance and cardiac output?

BACKGROUND: In patients with chronic heart failure there is no relation between cardiac output and symptom limited exercise tolerance measured on a bicycle or treadmill. Furthermore, the increase in cardiac output in response to treatment may not be matched by a similar increase in exercise tolerance. More important in determining exercise capability is blood flow to skeletal muscle. This implies that the reduction in skeletal muscle blood flow is not directly proportional to the reduction in cardiac output and that there are regional differences in blood flow in patients with heart failure. METHODS: Cardiac output and regional blood flow measured in 30 patients with chronic heart failure were compared with values obtained from 10 healthy controls. Measurements were made at rest and in response to treadmill exercise and were all made non-invasively. RESULTS: Cardiac output was lower in the patients at rest and during exercise. Blood flow in the superior mesenteric and renal arteries was also lower in the patients and represented a different proportion of cardiac output than in the controls. In response to exercise the increase in blood flow to the calf and therefore to skeletal muscle, was reduced in the patients. In the patients there was no correlation between resting cardiac output and blood flow in the superior mesenteric artery, renal artery, or calf. CONCLUSIONS: Because blood flow to skeletal muscle and to the kidneys is likely to be important in determining patients' symptoms this factor may explain why central haemodynamic variables do not correlate with the exercise tolerance in patients with chronic heart failure.

Aged↗

PubMed1993

Measurement of cardiac output by automated single-breath technique, and comparison with thermodilution and Fick methods in patients with cardiac disease.

Accurate noninvasive methods are needed for determination of cardiac output. Current methods are generally complex or may be unreliable. A previously described method, based on absorption of acetylene gas during a constant exhalation that enables calculation of cardiac output by estimating pulmonary capillary circulation, is incorporated in a new, automated commercial product (SensorMedics 2200). In this study, cardiac output by single-breath acetylene blood flow measured with this device was compared with the standard thermodilution and direct Fick methods in 20 patients undergoing cardiac or pulmonary artery catheterization. Patients inhaled test gas mixture to total lung capacity and exhaled at a constant rate through an adjustable resistor. Lung volumes and noninvasive acetylene blood flow value were calculated automatically. Correlation between the automated single-breath technique and both thermodilution and Fick cardiac output determinations was very high (correlation coefficients were 0.90 and 0.92, respectively), regression slopes were close to identity (0.98 and 0.90), and bias (-0.39 and -0.79 liter/min) and precision (0.94 and 1.02) were good; when shunt correction was applied, bias was reduced to 0.06 and 0.35 liter/min, respectively. Rapid, accurate, noninvasive measurement of cardiac output was easily obtained using the automated device. This technique may have a wide applicability for noninvasive evaluation of patients with cardiac disease and for monitoring effects of therapeutic interventions.

Absorption↗

PubMed1994

Variability of cardiac output over time in medical intensive care unit patients.

OBJECTIVES: To determine the amount of spontaneous variability of cardiac output over time in critically ill patients, and to determine the effect of mechanical ventilation on cardiac output variability over time. DESIGN: Case series. SETTING: Medical intensive care unit in a Veterans Affairs Medical Center. PATIENTS: Twenty-two patients with indwelling pulmonary artery flotation catheters were studied. Two patients were studied twice. INTERVENTIONS: During a 1-hr time period in which no interventions were required or made, thermodilution cardiac output was determined at baseline and then every 15 mins for 1 hr. At each time point, five individual cardiac output measurements were made and a mean was computed. The covariables of heart rate, respiration rate, mean arterial pressure, mean pulmonary arterial pressure, pulmonary artery occlusion pressure, and temperature were also recorded at each time point. MEASUREMENTS AND MAIN RESULTS: The variability of the five cardiac output measurements made at each time point was expressed by calculating for each patient a coefficient of variation of the measurements. The overall mean coefficient of variation of the measurements was 5.8%. The variability of the cardiac output measurements over time was expressed by calculating for each patient a coefficient of variation over time. The overall mean coefficient of variation over time was 7.7%. A subgroup of 15 "covariable stable" patients (defined as those patients with covariables within +/- 5% of the mean covariable values during the hour) had a mean coefficient of variation over time of 6.4%, whereas "covariable unstable" patients (with > +/- 5% changes in any covariable) had a mean coefficient of variation over time of 9.9% (p < .05). Patients breathing spontaneously had a mean coefficient of variation over time of 10.1%, whereas mechanically ventilated patients had a mean coefficient of variation over time of 6.3% (p < .05). CONCLUSIONS: The spontaneous variability of cardiac output should be considered when interpreting two cardiac output determinations made at separate times. Due to spontaneous variability alone, a patient with a baseline cardiac output of 10.0 L/min would be expected (95% confidence interval) to have a cardiac output range of 9.2 to 10.8 L/min if covariables were stable, and a range of at least 8.8 to 11.2 L/min if covariables were unstable. Patients who were mechanically ventilated displayed less variability than patients who were breathing spontaneously.

Adult↗

PubMed1981

Comparison of two closed systems for thermodilution cardiac outputs.

The authors used an in vitro flow system to evaluate the sources of error in a previously described closed system thermodilution method for cardiac output determinations. Cardiac outputs were overestimated by as much as 49% because the injectate warmed as it was drawn through the connecting tubing. Submerging the tubing in the ice bath prevented this problem. The authors also evaluated a new closed system thermodilution cardiac output method. The method employed a bypass line and a spring loaded autosyringe which enables the user to flush the system with cold fluid, thereby ensuring accurate injectate temperatures. Cardiac output determinations with this method were as accurate as those obtained with a CO2 powered injector. Additionally, this method is easy to use, accommodates injection volumes of 1-10 ml, and is inexpensive.

Cardiac Output↗

PubMed1990

[Noninvasive measurement of cardiac output by pulsed Doppler echocardiography. Correlation with thermodilution].

Cardiac output was measured simultaneously by pulsed Doppler echocardiography and thermodilution in 22 patients, 18 of whom also underwent atrial pacing at different rates to give a total of 42 different measurements. The aortic diameter was measured firstly at the aortic ring at the level of insertion of the aortic cusps and then at the point of maximum separation of the valve cups in the left parasternal long-axis view. The aortic velocities were recorded in the apical 5-chamber view immediately below the level of the aortic valve. The correlations obtained at the aortic ring (R1) and at the point of maximum separation of the valve cusps (R2) were 0.77 (y = 0.67x + 1.17: standard error = 0.81 l/m) and 0.64 (y = 0.56x + 0.87; standard error = 1.01 l/mn) respectively. The correlations were much better when 7 technically unsatisfactory measurements were excluded (R2 = 0.76: y = 0.59x + 0.74: standard error = 0.79 l/mn) (R1 = 0.87: y = 0.72x + 1.04: standard error = 0.65 l/mn). THe correlations of stroke volume measured at aortic ring level also improved from r = 0.82 (y = 0.75x + 7.29: standard error = 8.9 ml) to r = 0.89 (y = 0.78x + 7.38: standard error = 7.3 ml). The measurement of cardiac output by pulsed Doppler echocardiography in the aortic root seems to be reliable. The correlations of the values of stroke volume and cardiac output with the thermodilution method are good, allowing detection of beat-to-beat variations of cardiac output, in suitable patients in the hands of experienced operators.

Adult↗

PubMed1997

Comparison of the accuracy of the lithium dilution technique with the thermodilution technique for measurement of cardiac output.

A new indicator dilution technique for measurement of cardiac output is described. Lithium chloride is injected via a central venous catheter and its dilution curve measured in arterial blood using a lithium-selective electrode. We assessed the lithium dilution cardiac output measurement (LiDCO) and a conventional thermodilution cardiac output measurement (ThDCO) by comparing the results of both with cardiac output determined by electromagnetic flowmetry (EMCO) under controlled laboratory conditions in 10 swine. They were monitored with a pulmonary artery catheter, femoral artery catheter and electromagnetic flowmeter placed around the ascending aorta. LiDCO, ThDCO and EMCO measurements were determined at baseline, in a hyperdynamic state produced by administration of dobutamine, at a second baseline and finally in a hypodynamic state induced by propranolol during deep anaesthesia. Data were analysed by linear regression analysis and the comparison method described by Bland and Altman; bias and precision of both LiDCO and ThDCO compared with EMCO were calculated by the method of Sheiner and Beal. The correlation coefficient between LiDCO and EMCO (0.95) was higher than that between ThDCO and EMCO (0.87). The precision value of LiDCO (0.04) was significantly less (i.e. better) than that of ThDCO (0.09). The results of this study indicated that LiDCO was more reliable compared with conventional ThDCO.

Animals↗