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PubMed1997

[High cardiac output in myeloma patients. Its prevalence and clinical characteristics. The Castile-León Cooperative Group for the Study of Monoclonal Gammapathies].

BACKGROUND: The study determines the prevalence of high cardiac output status in patients with multiple myeloma (MM) and its relationship with the more significant clinical and biological characteristics of the disease. PATIENTS AND METHODS: Cardiac output was determined in 28 patients with multiple myeloma by pulsed Doppler echocardiography. Patients with any other identifiable cause of high cardiac output were excluded. Mean age was 70 +/- 8 SD years (53-84). A stepwise regression with the cardiac output as dependent variable and age, performance status (ECOG), clinical stage (Durie and Salmon), scale of bone lesions, serum calcium, serum creatine, bone involvement (percentage), and M protein quantity as independent variables showed the following results. RESULTS: A high cardiac output state, defined as a cardiac index higher than 4.6 l/min/m2 was present in five patients (17.8%), four of them with severe bone involvement. Two patients developed heart failure. The stepwise regression revealed the scale of bone lesions was the unique variable associated with the risk of developing a high cardiac output status. CONCLUSIONS: A high cardiac output status may be fairly common in patients with multiple myeloma. The syndrome is associated with severe bone involvement, being the scale of bone lesions the only risk factor for this complication.

Aged↗
PubMed1995

Noninvasive monitoring of cardiac output by Doppler echocardiography in patients treated with volume expansion after subarachnoid hemorrhage.

OBJECTIVE: To assess the validity and potential clinical utility of cardiac output monitoring using Doppler echocardiography in patients treated with volume expansion after subarachnoid hemorrhage. DESIGN: Observational study of patients in a randomized, clinical trial. SETTING: Neurologic intensive care unit. PATIENTS: Simultaneous, blinded measurements of cardiac output by thermodilution and Doppler echocardiography were performed in 48 patients 1 or 2 days after aneurysmal clipping. Follow-up Doppler echocardiography was performed an average of 3.9 days later (range 3 to 6) in 15 patients assigned to normovolemia and 24 patients assigned to hypervolemia. INTERVENTION: Patients received supplemental 5% albumin in order to maintain increased (hypervolemia) or normal (normovolemia) cardiac filling pressures. MEASUREMENTS AND MAIN RESULTS: The overall degree of correlation between the two measures was moderate (r = .67, r2 = .45, p < .0001). Bias and precision calculations (-0.75 +/- 1.34 L/min) showed a tendency for Doppler echocardiography to underestimate thermodilution, particularly when cardiac output was very high. Although hypervolemia patients received more 5% albumin than normovolemia patients, mean percent change in Doppler echocardiography cardiac output did not differ between the two groups. Multiple regression analysis showed that the percent change in Doppler echocardiography cardiac output correlated strongly with changes in heart rate (p < .0001), but not with daily net fluid balance or 5% albumin administration. CONCLUSIONS: Agreement was poor between Doppler echocardiography and thermodilution measurements of cardiac output, and trends reflected variations in heart rate rather than fluid status. Monitoring of cardiac output by this technique cannot be recommended in patients treated with volume expansion after subarachnoid hemorrhage.

Adult↗
PubMed1994

Carbon dioxide rebreathing method of cardiac output measurement during acute respiratory failure in patients with chronic obstructive pulmonary disease.

OBJECTIVE: To compare measurement of cardiac output by the CO2 rebreathing method vs. the thermodilution cardiac output technique in the setting of acute respiratory failure in patients with chronic obstructive pulmonary disease. DESIGN: Prospective, comparative study of two methods in a consecutive sample. SETTING: Intensive care unit. PATIENTS: Twenty-five patients with chronic obstructive pulmonary disease with acute respiratory failure were studied. The patients were being mechanically ventilated and monitored with systemic and pulmonary artery catheters. MEASUREMENTS AND MAIN RESULTS: Cardiac output was determined, using both the thermodilution technique and an indirect CO2 Fick method. Veno-arterial CO2 content difference was calculated from an estimated mixed venous PCO2 obtained by an equilibrium CO2 rebreathing method and measured PaCO2. PCO2 was converted to content using the equation of the CO2 dissociation curve described by McHardy. A wide range of cardiac output was studied. There was a significant correlation between thermodilution and CO2 rebreathing methods (r2 = .92, p < .001). The mean difference between thermodilution and CO2 rebreathing methods was -0.06 L/min/m2, standard deviation for the bias was 0.028 L/min/m2, and 95% confidence interval for the bias was -0.120 to -0.001 L/min/m2. CONCLUSION: Our results suggest that the CO2 rebreathing method may be a reliable non-invasive technique to determine cardiac output in mechanically ventilated patients with chronic obstructive pulmonary disease.

Acute Disease↗
PubMed1972

Regional distribution of cardiac output in young lambs: effect of cold exposure and treatment with catecholamines.

1. Lambs less than 3 days old, exposed to thermoneutral or intensely cold conditions in a respiration chamber, were infused with adrenaline or noradrenaline, 1 or 10 mug/kg.min; and the effects on oxygen consumption, cardiac output and its distribution to skin, skeletal and cardiac muscle, liver, spleen, kidney, gut, brown adipose tissue and brain were determined. Cardiac output was estimated by the Fick and dye dilution methods and the distribution of cardiac output by Sapirstein's method of fractional distribution of indicators.2. Under thermoneutral conditions, metabolic rate was stimulated by both doses of noradrenaline and by the low, but not the high dose of adrenaline. Under cold conditions, the low dose of catecholamines had little effect on the already elevated metabolic rate, but the high doses depressed the metabolic response to cold.3. The low dose of adrenaline increased cardiac output under thermoneutral conditions whereas the high dose decreased cardiac output; the effects of noradrenaline were less marked, in contrast to reported effects in new-born rabbits. The low doses of catecholamine given under cold conditions had little effect on the already elevated cardiac output, but the high doses, particularly of adrenaline, decreased cardiac output.4. Blood flow through the skin of the extremities was markedly reduced by cold exposure, while flow through the peri-renal fat was doubled, flow through the skeletal muscle was quadrupled and flow through the cardiac muscle was trebled. These increases, particularly in skeletal muscle, were due to increased cardiac output and to vasodilation, as indicated by the reduced ratio of blood pressure to blood flow. Results are contrasted with published reports that blood flow through brown fat in new-born rabbits was greatly increased by cold, but muscle flow was scarcely altered.5. In almost all organs examined the high doses of adrenaline infused in either environment markedly reduced blood flow, presumably by generalized vasoconstriction. Changes due to noradrenaline were small under thermoneutral conditions and flow through brown fat was increased by only 60% during infusion of 10 mug/kg.min. Much greater increases have been reported in new-born rabbits. Under cold conditions the high doses of noradrenaline tended to decrease flow in most organs including brown fat and muscle.6. The results provide likely explanations for published reports that adrenaline failed to stimulate non-shivering thermogenesis or suppressed the mobilization of metabolites and the metabolic response to cold.

Adipose Tissue, Brown↗
PubMed2006

Effects of hydroxyethyl starch on cardiac output in hypotensive neonates: a comparison with isotonic saline and 5% albumin.

AIM: To evaluate the effects of hydroxyethyl starch (6% HES 200/0.5) on cardiac output in hypotensive neonates with low cardiac output and absence of myocardial dysfunction. METHODS: In a prospective randomized blinded trial, 21 hypotensive neonates (mean gestational age of 29+/-3 wk) were randomly allocated to receive infusions of either 5% albumin (albumin group), isotonic saline (saline group) or hydroxyethyl starch (HES group). Infants had to show low cardiac output and an absence of myocardial dysfunction for inclusion in the study. Cardiac output was assessed by Doppler-derived mean aortic flow velocity. RESULTS: Ten minutes after infusion, 67% of all infants had more than a 10% increase in cardiac output. Increases in mean aortic flow velocity (m/s; median and range) were 0.05 (-0.02, +0.07), 0.03 (-0.03, +0.12) and 0.03 (-0.04, +0.11) for the albumin, saline and HES groups, respectively (p = 0.79). The percentage of blood pressure normalization (95% confidence interval) was 86% (60-100) in the albumin group, 57% (20-94) in the saline group and 71% (37-100) in the HES group (p = 0.50). CONCLUSION: This study did not provide evidence that hydroxyethyl starch is more efficient than isotonic saline or albumin.

Albumins↗
PubMed1987

Constant postoperative monitoring of cardiac output after correction of congenital heart defects.

A new method has been developed that permits constant postoperative monitoring of mean and phasic cardiac output in patients after correction of congenital heart defects. A miniature ultrasound probe is attached to the adventitia of the ascending aorta at the conclusion of the operative procedure. This is connected to the monitoring equipment by means of polyurethane-covered wires that exit the chest wall through a small stab wound. The probe can easily be removed by gentle traction when the patient's condition is stable. The technique was developed, validated, and refined in extensive animal studies, and this report describes the first series of 20 consecutive human implants, performed between August 1984 and September 1985, in which the absolute cardiac output determination obtained with the ultrasound probe at the time of its application was correlated with cardiac output as measured with a standard electromagnetic flow probe. Fourteen male and six female patients (mean age 5.5 years) were studied. Operations performed included eight atrial septal defect repairs, four procedures for tetralogy of Fallot, three ventricular septal defect repairs, three stenotic valve corrections, and two Senning operations. One operative death occurred, but no complications were related to probe application or removal. The average cardiac output in the 20 patients as measured with the ultrasound probe was 2.2 +/- 1.1 L/min (range 0.67 to 5.27 L/min). This is nearly identical to the results noted with the electromagnetic flow probe, where the mean cardiac output was 2.3 +/- 1.2 L/min (range 0.7 to 6 L/min). Regression analysis revealed a high linear correlation (r = 0.9) between the two techniques. A monitor can display the cardiac output trend with 1 minute updates, which greatly enhance management of intravenous drug therapy and volume administration. In conclusion, this new extraluminal removable probe allows virtually continuous monitoring of the postoperative cardiac output after correction of congenital heart defects and should become a standard technique in the postoperative care of these patients.

Adolescent↗
PubMed1975

The peri-operative measurement of cardiac output in infancy by the thermodilution technique.

Cardiac output has been measured in infants by thermodilution during and after surgery. A method employing commerically available equipment has been developed. An animal model has been devised whereby right heart outputs of 210 ml to 2240 ml, measured by thermodilution, could be compared with left heart outputs measured by an aortic by-pass. The results of this study suggest that thermodilution is a simple, accurate method for measurement of cardiac output in infancy.

Age Factors↗
PubMed1990

Accuracy of mitral Doppler echocardiographic cardiac output determinations in adults.

The Doppler echocardiographic estimation of cardiac output at the mitral valve site is often underestimated in adults with slow heart rates because the mitral valve remains open in mid-diastole when flow is markedly reduced. Therefore we tested several approaches to this measurement in 17 adults with nonvalvular heart disease who had thermodilution catheters in the right side of the heart. Superior correlations with thermal output values were obtained by a new method that excludes mitral orifice measurements during mid-diastole when flow less than 10 cm/sec (r = 0.94) compared with the standard method (r = 0.89). Also, the new method resulted in significantly less underestimation of thermal cardiac output in patients with heart rates less than 70 beats/min (-10%) compared with the standard method (-34%). In addition, use of a constant maximal two-dimensional echocardiographic mitral orifice correction factor of 0.77 with the new method to account for variations in mitral valve orifice during the cardiac cycle, as opposed to 0.68 with the standard method, resulted in similar results as compared with determining individual correction factors from M-mode echoes. We conclude that: (1) the mitral orifice approach is accurate for measuring cardiac output in adult patients with nonvalvular heart disease; (2) a new method that excludes mid-diastolic mitral orifice measurements is superior to the standard method; and (3) use of a constant two-dimensional echocardiographic mitral valve orifice correction factor obviates the need for M-mode echoes.

Cardiac Output↗
PubMed1992

Intraoperative determination of cardiac output by transesophageal continuous wave Doppler.

A new prototype transesophageal transducer with continuous-wave Doppler and pulsed Doppler capabilities was evaluated to calculate intraoperative cardiac output from the main pulmonary artery. Fifteen consecutive patients undergoing elective coronary artery bypass surgery were studied. The main pulmonary artery diameter above the pulmonic valve was measured with the single horizontal plane transesophageal transducer. The pulmonary artery cross-sectional area was calculated from its diameter using the formula: Area = 1/4 pi (diameter)2. Continuous-wave Doppler and pulsed Doppler spectra were recorded from the main pulmonary artery and their flow velocity integrals were then multiplied by pulmonary artery area and heart rate to yield cardiac output. The main pulmonary artery diameter could not be confidently measured in 2 of 15 patients (13%). In the remaining 13 patients, Doppler cardiac output measurements were correlated with simultaneous thermodilution measurements. The closest correlation with thermodilution cardiac output was with the continuous-wave Doppler cardiac output method: R = 0.91, SEE = 0.2 L/min, and y = 1.1x . 0.2 (p less than 0.001). The correlation of thermodilution with pulsed Doppler cardiac output was R = 0.83, SEE = 0.5 L/min, and and y = 0.86 + 1.0 (p less than 0.001). Transesophageal continuous-wave Doppler is a new technique that may be used in selected patients for accurate determination of intraoperative cardiac output.

Adult↗
PubMed1996

Measurement of cardiac output by transoesophageal Doppler echocardiography in anaesthetized horses: comparison with thermodilution.

In order to determine if transoesophageal Doppler echocardiography could be used to estimate cardiac output in anaesthetized horses, we have compared the technique with estimations of cardiac output by thermodilution in eight healthy adult thoroughbreds. Measurements of aortic blood flow velocity were made by high pulse repetition frequency (HPRF) and continuous wave (CW) Doppler echocardiography from a 3.5-MHz transoesophageal probe. Cardiac output was increased during the study by administration of dobutamine, providing a range of cardiac output measurements by thermodilution from 15.0 to 64.4 liter min-1. Estimations derived from CW Doppler overestimated cardiac output compared with thermodilution (bias = 4.0 litre min-1). Estimations from HPRF Doppler echocardiography more closely reflected measurements obtained by thermodilution (bias = 0.7 litre min-1). Limits of agreement between the techniques were similar for both modes of insonation (HPRF = -7.7 to 9.1 litre min-1, CW = -4.9 to 12.8 litre min-1). There were significant differences in bias between both Doppler techniques and thermodilution for individual horses. As a result, for any individual horse, limits of agreement between the techniques were closer (HPRF = +/- 6.4 litre min-1, CW = +/- 7.6 litre min-1). We conclude that transoesophageal echocardiography provided an alternative, effective and non-invasive method for measurement of cardiac output in anaesthetized horses.

Anesthesia, General↗
PubMed2002

Effects of acute volume loading and hemorrhage on intestinal vascular capacitance: a mechanism whereby capacitance modulates cardiac output.

BACKGROUND: Changes in intestinal vascular capacitance during acute volume loading and hemorrhage have not been described. OBJECTIVES: To determine the effects of volume loading and hemorrhage on the intestinal vascular pressure-volume relationship and cardiac output. PATIENTS AND METHODS: In 11 alpha-chloralose-anesthetized dogs, a pneumatic portal venous constrictor and catheter were positioned to increase and measure portal venous pressure (Ppv), respectively. Relative changes in intestinal blood volume (IBV) were determined by blood-pool scintigraphy and expressed as the percentage change from control values (taken as 100%). Ppv-IBV relationships were constructed by graded portal vein constriction. RESULTS: IBV and cardiac output increased by 60 6% and 178 48%, respectively, and Ppv increased from 5.8 0.9 mmHg to 13.2 1.8 mmHg after initial volume loading (40 mL/kg of an isotonic glucose-saline solution over 7 min). IBV gradually decreased and reached near-control values after 75 min. In seven dogs, hemorrhage (sufficient to decrease mean aortic pressure by 56 4%) decreased IBV and cardiac output to 88 4% and 52 3% of control values, respectively, and Ppv decreased to 3.2 0.8 mmHg. CONCLUSIONS: A sigmoid function curve defined the relationship between cardiac output and IBV. Cardiac output remained constant over a wide range (between approximately 95% and 135% of control IBV). Outside this range, insufficient dilation or constriction resulted in a marked increase or decrease in venous pressures and cardiac output. These data indicate that vasculature capacitance modulates cardiac output during acute volume loading and hemorrhage, thereby maintaining cardiac output relatively constant over a wide range of total vascular blood volume.

Animals↗
PubMed1977

Cardiac output and regional blood flow in untreated and triglycylvasopressin-treated burned mice.

Cardiac output and regional blood flow to different organs were determined at one hour and at 24 hours after burn in untreated mice and in mice treated with triglycylvasopressin (TGLVP). A decrease in cardiac output was found in all animals at one hour after burn. At 24 hours cardiac output was decreased in the burned untreated group, while cardiac output of TGLVP-treated animals did not differ from that of unburned animals. Organ blood flow was decreased in all animals at one hour after burn. Such a decrease was seen in the untreated group also at 24 hours after burn, while organ blood flow in the TGLVP-treated group had returned to preburn values.

Animals↗
PubMed2002

Cardiac output assessed by arterial thermodilution during exsanguination and fluid resuscitation: experimental validation against a reference technique.

BACKGROUND AND OBJECTIVE: The arterial thermodilution technique offers the ability to measure cardiac output using only central venous and arterial catheters. However, the technique has been reported to overestimate cardiac output because of a higher loss of cold indicator due to the increased distance between the sites of injection and measurement. In this study, the two techniques were compared with respect to conditions of low cardiac output in which a longer passage time may further increase loss of indicator. METHODS: Seventeen anaesthetized dogs were studied during hypovolaemic shock and fluid resuscitation. Cardiac output measurements were carried out simultaneously by arterial and pulmonary artery thermodilution techniques. RESULTS: One-hundred-and-two measurements were performed. The mean cardiac output was 2.28 +/- 1.4Lmin(-1) by the pulmonary arterial technique and 2.29 +/- 1.56Lmin(-1) by the arterial thermodilution technique. The correlation coefficient between the two measurements was 0.95, the precision -0.04 +/- 0.41 Lmin(-1) and the limits of agreement from -0.86 to 0.78Lmin(-1). The agreement was also consistent at low cardiac outputs. CONCLUSIONS: The arterial thermodilution technique may serve as a less invasive cardiac output monitor in conditions of severe bleeding and shock.

Animals↗
PubMed1998

Sevoflurane pharmacokinetics: effect of cardiac output.

Sevoflurane uptake (Vsevo) can be predicted by the square root of time model or the four-compartment model. However, Vsevo and the effect of cardiac output on anaesthetic uptake have not been quantified clinically. After obtaining IRB approval and informed consent, 34 adult patients received closed-circuit anaesthesia with sevoflurane for 1 h. The end-expired sevoflurane concentration was maintained at 2.6% by infusion of liquid sevoflurane into the breathing system. In a subgroup of 12 patients, cardiac output was measured every 5 min by thermodilution (CO group). The effect of patient characteristics (age, height, weight, body surface area) and cardiac output on Vsevo were determined, and Vsevo was compared with the theoretical models. In the CO group, measured cardiac output was used in the formulae of these models. A two-exponential curve described average Vsevo well: Vsevo (ml liquid) = 0 + 1.62 x (1 - e(-2.3)xt) + 18.1 x (1 - e(-0.0089xt), r2 > 0.999. There was no correlation between Vsevo and patient characteristics, except that Vsevo was greater in patients with a greater cardiac output (r2 = 0.36) and cardiac index (r2 = 0.35). The rate of sevoflurane uptake decreased less than predicted by the square root of time and four-compartment models, even when measured cardiac output was used in the formulae. These findings confirm that the square root of time and four-compartment models do not accurately predict anaesthetic uptake. In addition, uptake of sevoflurane cannot be predicted by patient characteristics but was higher in patients with a higher cardiac output.

Adolescent↗
PubMed1987

Echo Doppler assessment of cardiac output and its relation to growth in normal infants.

In a study of 38 normal infants, serial measurements of systemic (n = 169) and pulmonary (n = 143) blood flow were undertaken from the ages of 2 weeks to 12 months by 2-dimensional, M-mode and pulsed Doppler echocardiography. Cardiac output changed linearly (cardiac output = 0.3 X height -0.99 liter/min), and cardiac index was validated as a means for standardizing cardiac output in infants younger than 10 to 13 months of age. Infants younger than 2 months had lower cardiac indexes and stroke volume indexes (2.6 +/- 0.7 liters/min/m2 and 19 +/- 5 ml/m2, respectively) compared with those aged 12 months (3.2 +/- 0.7 liter/min/m2 and 25 +/- 5 ml/m2, respectively). Changes in cardiac output in individual infants over time suggest nonmorphometric modulating factors for cardiovascular function.

Age Factors↗
PubMed1989

Determination of cardiac output in critically ill patients by dual beam Doppler echocardiography.

Recent technology in Doppler echocardiography has produced a dual beam Doppler instrument that is capable of insonating the total cross-sectional area of the ascending aorta. The purpose of this study was to evaluate the accuracy of this instrument in measuring cardiac output in critically ill patients by comparing results with those of the thermodilution-derived cardiac output. A technically adequate Doppler cardiac output measurement was attained in 71 (91%) of 78 patients. The range of thermodilution-derived cardiac output measurements was from 1.58 to 11.70 liters/min. To maximize thermodilution cardiac output reliability, several measurements were made for each patient. Those patients in whom the difference between the highest and lowest measurement varied by less than 10% from the averaged results were accepted into the 50 patient study. There was significant correlation between dual beam Doppler- and thermodilution-derived cardiac output (r = 0.96, SEE = 0.55 liters/min, p less than 0.0001). This study demonstrates that dual beam Doppler ultrasound is a promising noninvasive method of measuring cardiac output in the critically ill patient.

Acute Kidney Injury↗
PubMed2005

Testing the reliability of a new ultrasonic cardiac output monitor, the USCOM, by using aortic flowprobes in anesthetized dogs.

We have used an animal model to test the reliability of a new portable continuous-wave Doppler ultrasonic cardiac output monitor, the USCOM. In six anesthetized dogs, cardiac output was measured with a high-precision transit time ultrasonic flowprobe placed on the ascending aorta. The dogs' cardiac output was increased with a dopamine infusion (0-15 microg x kg(-1) x min(-1)). Simultaneous flowprobe and USCOM cardiac output measurements were made. Up to 64 pairs of readings were collected from each dog. Data were compared by using the Bland and Altman plot method and Lin's concordance correlation coefficient. A total of 319 sets of paired readings were collected. The mean (+/-sd) cardiac output was 2.62 +/- 1.04 L/min, and readings ranged from 0.79 to 5.73 L/min. The mean bias between the 2 sets of readings was -0.0l L/min, with limits of agreement (95% confidence intervals) of -0.34 to 0.31 L/min. This represents a +/-13% error. In five of six dogs, there was a high degree of concordance, or agreement, between the 2 methods, with coefficients >0.9. The USCOM provided reliable measurements of cardiac output over a wide range of values. Clinical trials are needed to validate the device in humans.

Animals↗
PubMed1991

Cardiac output measurement in critical care patients: Thoracic Electrical Bioimpedance versus thermodilution.

Thoracic Electrical Bioimpedance (TEB) is a method for measuring cardiac performance which is noninvasive, continuous, has minimal technical requirements, and no patient risk. We used a commercially available TEB device to measure cardiac output in patients with thermodilution catheters in place. We compared the cardiac output measurements for the two modalities. We also compared the average hospital cost for initial cardiac assessment using the two techniques. The mean difference between the two cardiac output measurements was small (0.23 +/- 0.56) and not affected by the magnitude of the cardiac output readings. There was a strong correlation between COTD and COTEB (r = 0.91) and the regression slope was 0.91 with a Y intercept of 0.76. Cost analysis demonstrated that the use of TEB was approximately $600 less than thermodilution. Thoracic electrical bioimpedance measurement of cardiac output may offer a valuable alternative to the invasive measurement of the thermodilution catheter.

Adolescent↗