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At least 343 records · Page 19Linked to original sources
PubMed2003

A comparison of CardioQ and thermodilution cardiac output during off-pump coronary artery surgery.

OBJECTIVE: To compare CardioQ esophageal Doppler cardiac output and thermodilution cardiac output during off-pump coronary artery bypass surgery. DESIGN: Prospective clinical study. SETTING: University-affiliated teaching hospital PARTICIPANTS: Adult patients (n = 20) undergoing elective coronary artery bypass surgery without cardiopulmonary bypass. MEASUREMENTS AND MAIN RESULTS: Three hundred thirty-one comparisons of simultaneous CardioQ and thermodilution cardiac outputs were made. The Pearson correlation coefficient for the pooled data was 0.62. Using a Bland-Altman approach, the overall bias was -0.56 L/min with a precision of 0.64 L/min. The 95% limits of agreement (bias +/- 2 SD) were -0.56 +/- 1.28 L/min. For individual patients, the bias ranged from -1.35 L/min to 0.27 L/min and the precision from 0.24 L/min to 0.74 L/min. CONCLUSION: Because of the wide limits of agreement and the large interpatient differences in both bias and precision, the CardioQ esophageal Doppler cardiac output cannot currently be recommended as an alternative to thermodilution cardiac output during off-pump coronary artery bypass surgery.

Adult↗
PubMed1998

A multicenter evaluation of a new continuous cardiac output pulmonary artery catheter system.

OBJECTIVE: To validate a new system of continuous cardiac output monitoring. DESIGN: Multicenter, prospective, nonrandomized clinical study. SETTING: Four university hospitals. PATIENTS: Forty-seven adult intensive care unit patients. INTERVENTIONS: Pulmonary artery catheterization. MEASUREMENTS AND MAIN RESULTS: Continuous and bolus cardiac output measurements were obtained over 72 hrs. The 327 continuous cardiac output measurements compared favorably with bolus cardiac output measurements (bias = 0.12 L/min, precision = +/-0.84). The continuous cardiac measurement was not adversely affected by temperatures of <37 degrees C or >38 degrees C, high (>7.5 L/min) or low (<4.5 L/min) cardiac output values, or duration (72 hrs) of the study. CONCLUSIONS: This continuous cardiac output system provides a reliable estimate of cardiac output for clinical use if applied in conditions similar to this study. The combination of a continuous measure of cardiac output with other continuous physiologic monitoring (arterial and mixed venous oxygen saturation, oxygen consumption, etc.) may provide important information that no single parameter could achieve.

Adolescent↗
PubMed1982

Oxygen uptake, plasma catecholamines and cardiac output during neurolept-nitrous oxide and halothane anaesthesias.

Cardiac output, oxygen uptake and plasma catecholamines were studied in patients both awake and during anaesthesia prior to and during upper abdominal surgery. Two different forms of anaesthesia were used: neurolept-nitrous oxide (NLA) and halothane (HALO) anaesthesia. Oxygen uptake was determined by using a masspectrometer, and cardiac output was measured according to the Fick principle. Plasma catecholamines were analysed by high performance liquid chromatography. Cardiac output fell by 40% during NLA and by 30% during HALO. Concomitantly, the oxygen uptake fell by 40% and 35%, respectively. A linear relationship between cardiac output and oxygen uptake could be established both in the awake state and during anaesthesia, with no significant change in the slope or position of the regression line when anaesthesia was commenced. Ventricular filling pressures fell during both anaesthetic procedures. Adrenaline fell to half the plasma concentrations seen in normal subjects under resting conditions, while noradrenaline returned to normal from an initially 30-40% increased value. Surgery caused no significant changes in either cardiac output or oxygen uptake, whereas plasma adrenaline increased by 20 times and noradrenaline by 60-90%. The findings suggest that the reduced oxygen uptake during anaesthesia causes the fall in cardiac output rather than any cardiodepressant action of the anaesthetic. It is possible that the anaesthetic depresses whole-body metabolism by either blocking the effects of catecholamines or interfering with cellular metabolism.

Aged↗
PubMed2005

Low cardiac output syndrome: identification and management.

Low cardiac output syndrome (LCOS) is a clinical condition that is caused by a transient decrease in systemic perfusion secondary to myocardial dysfunction. The outcome is an imbalance between oxygen delivery and oxygen consumption at the cellular level which leads to metabolic acidosis. Although LCOS is observed most commonly in patients after cardiac surgery, it may present in various disease processes resulting in cardiac dysfunction. This article provides an overview of the determinants involved in oxygen transport, the physiologic factors influencing cardiovascular function, the assessment of hemodynamic variables, the etiology of LCOS, and management strategies, including a brief review of some pharmacologic agents that are used in the treatment of low cardiac output.

Blood Gas Analysis↗
PubMed2001

Modeling population pharmacokinetics of lidocaine: should cardiac output be included as a patient factor?

BACKGROUND: Inclusion of cardiac output and other physiologic parameters, in addition to or instead of, demographic variables might improve the population pharmacokinetic modeling of lidocaine. METHODS: Thirty-one patients were included in a population pharmacokinetic study of lidocaine. After bolus injection of lidocaine (1 mg/kg), 22 or 10 blood samples per patient were taken from a radial artery. During the experiment, cardiac output was measured using a thoracic electrical bioimpedance method. The following four population pharmacokinetic models were constructed and their performances investigated: a model with no covariates, a model with cardiac output as covariate, a model with demographic covariates, and a model with both cardiac output and demographic characteristics as covariates. Model discrimination was performed with the likelihood ratio test. RESULTS: Inclusion of cardiac output resulted in a significant improvement of the pharmacokinetic model, but inclusion of demographic covariates was even better. However, the best model was obtained by inclusion of both demographic covariates and cardiac output in the pharmacokinetic model. CONCLUSIONS: When population pharmacokinetic models are used for individualization of dosing schedules, physiologic covariates, e.g., cardiac output, can improve their ability to predict the individual kinetics.

Adult↗
PubMed1980

Control of fetal cardiac output during changes in blood volume.

Changes in cardiac output (Qco), heart rate, right atrial pressure, (Pra), and mean systemic pressure (Pms) in response to blood volume changes were measured in chronically prepared fetal sheep. With a 10% decrease in blood volume, fetal cardiac output, measured with the microsphere technique, decreased significantly from 592 +/- 28 to 471 +/- 32 ml . min-1 . kg-1. Heart rate changed little from control animals (163 +/- 5) to those with decreased volume (161 +/- 10 beats/min). Right atrial pressure decreased significantly from 5.4 +/- 0.4 to 4.2 +/- 0.6 mmHg. Mean systemic pressure decreased from 13.8 +/- 0.3 to 10.5 +/- 0.6 mmHg. With a 10% increase in fetal blood volume, cardiac output rose insignificantly to 632 +/- 38 ml . min-1 . kg-1. However, right atrial pressure increased significantly to 8.9 +/- 0.6 mmHg and mean systemic pressure increased significantly to 16.5 +/- 0.8 mmHg with the increased volume. Heart rate again changed little (153 +/- 9 beats/min). The fact that cardiac output rose only a small amount, whereas right atrial pressure rose sharply with an increased blood volume, suggests that the fetal heart is operating near the upper limit of its Starling function curve. As a result, there is very limited cardiac reserve for increases in fetal cardiac output.

Animals↗
PubMed1980

Regional blood flows in high-cardiac-output hypertension.

1. Mean arterial pressure, cardiac output (electromagnetic flow-meter) and regional blood flows (15 micrometer radioactive microspheres) were measured repeatedly in eight dogs receiving a salt and water load after renal mass reduction as well as in six control animals. 2. As previously observed, hypertension developed in the salt-loaded dogs with an initial increase in cardiac output followed by a secondary rise in total peripheral resistance. 3. Much of the early increase in cardiac output was distributed to the skeletal muscle vascular bed. 4. Total peripheral resistance changes did not reflect the resistance of individual vascular beds in the early stages of salt and water load hypertension; indeed, resistance in the muscle vascular bed was decreased and that in the splanchnic area and the bone increased on the first day of salt and water load when total peripheral resistance was unchanged.

Animals↗
PubMed1993

Cardiac output determination.

Critical care nurses frequently are involved in obtaining cardiac output measurements and in using these data to assess and to plan therapy. This article reviews the physiologic determinants of cardiac output and the clinical factors that influence these determinants. Principles and techniques of common methods of cardiac output measurement are discussed. A thorough presentation of guidelines for troubleshooting problems with thermodilution cardiac output measurement is provided in a table. Nursing management issues are discussed using relevant nursing research. Future considerations in cardiac output measurement are discussed, and suggestions of an ideal cardiac output system are provided.

Cardiac Output↗
PubMed2000

Endotracheal cardiac output monitor.

BACKGROUND: The endotracheal cardiac output monitor (ECOM) is a new device that uses an endotracheal tube with multiple electrodes to measure cardiac output (CO). It measures the changes in electrical impedance caused by pulsatile blood flow in the aorta. The system was tested for safety and efficacy in 10 swine. METHODS: Swine (60-80 kg) were chronically instrumented with a transit time flow probe on the ascending aorta and vascular occluders on the vena cava and pulmonary artery. After a minimum recovery of 4 days, the animals were anesthetized and intubated with an ECOM endotracheal tube. CO measurements from the ECOM system were compared to transit time flow probe measurements using linear regression and Bland-Altman analysis. Three different inotropic states were studied: (1) baseline; (2) increased (dobutamine); and (3) decreased (esmolol). CO was changed at each inotropic state by impeding left ventricular filling with the vena cava or pulmonary artery occluders. CO values between 0 and 15 l/min were studied. Pigs were studied for 24 h consecutively. RESULTS: There was no deterioration of the impedance signal with time and no tracheal injury from the ECOM electrodes. There is a linear relationship between the ECOM and transit time flow probe CO between 0 and 15 l/min (slope = 0.94; intercept = 0.15 l/min; R2= 0.77). The mean difference between the two measures (bias) is 0.15 l/min and the SD is 1.34 l/min. The limits of agreement are -2.53 to 2.82 l/min. CONCLUSION: Endotracheal CO monitor is a promising technology that needs further evaluation in clinical trials.

Adrenergic beta-Antagonists↗
PubMed1979

A computerised dichromatic earpiece densitometer for the measurement of cardiac output.

This study assesses a precalibrated dichromatic earpiece densitometer and microprocessor for the measurement of cardiac output by indocyanine green dye dilution. The measured cardiac output is compared with values of cardiac output simultaneously determined using a cuvette densitometer. The microprocessor computation of cardiac output agreed very closely with the cardiac output determined by manual calculation from the same dye dilution curves (standard deviation +/- 1.47%). The reproducibility of the earpiece densitometer (standard deviation +/- 5.2%) was virtually identical to that of the cuvette densitometer (+/- 5.3%). In a comparison of earpiece and cuvette densitometers for 60 measurements of cardiac output following pulmonary arterial injection of dye and for 50 measurements following femoral venous injection of dye, correlation coefficients were 0.83 and 0.78 and the standard deviations of the differences of simultaneous measurements were 7.2% and 8.3% respectively. The instrument offers an accurate reproducible and relatively noninvasive technique for measuring cardiac output.

Cardiac Output↗
PubMed1985

Effects of chemical sympathectomy with 6-hydroxydopamine on cardiac output and its distribution in the rat.

Cardiac output and its regional distribution were determined with radioactive microspheres in pentobarbitone anaesthetised rats 16 h and 5 days after sympathectomy with 6-hydroxydopamine (150 mg/kg i.p. over 24 h). Distribution was not different at either time in sympathectomised animals compared to controls given i.p. saline/ascorbic acid. Cardiac output was 12% greater 16 h after sympathectomy than in the controls but heart rate and blood pressure were 20% lower. Stroke volume was 43% greater in animals given 6-hydroxydopamine and total peripheral resistance 29% lower than in sham-sympathectomised rats. Five days after sympathectomy, blood pressure and heart rate were still lower in sympathectomised rats, but cardiac output and total peripheral resistance were not significantly different from control. It is concluded that basal sympathetic tone does not determine the distribution of cardiac output at rest and that its primary effect on the heart is to maintain heart rate rather than contractility.

Animals↗
PubMed1998

Effects of aging on cardiac output, regional blood flow, and body composition in Fischer-344 rats.

The purpose of this study was to determine the effects of maturation and aging on cardiac output, the distribution of cardiac output, tissue blood flow (determined by using the radioactive-microsphere technique), and body composition in conscious juvenile (2-mo-old), adult (6-mo-old), and aged (24-mo-old) male Fischer-344 rats. Cardiac output was lower in juvenile rats (51 +/- 4 ml/min) than in adult (106 +/- 5 ml/min) or aged (119 +/- 10 ml/min) rats, but cardiac index was not different among groups. The proportion of cardiac output going to most tissues did not change with increasing age. However, the fraction of cardiac output to brain and spinal cord tissue and to skeletal muscle was greater in juvenile rats than that in the two adult groups. In addition, aged rats had a greater percent cardiac output to adipose tissue and a lower percent cardiac output to cutaneous and reproductive tissues than that in juvenile and adult rats. Differences in age also had little effect on mass-specific perfusion rates in most tissues. However, juvenile rats had lower flows to the pancreas, gastrointestinal tract, thyroid and parathyroid glands, and kidneys than did adult rats, and aged rats had lower flows to the white portion of rectus femoris muscle, spleen, thyroid and parathyroid glands, and prostate gland than did adult rats. Body mass of juvenile rats was composed of a lower percent adipose mass and a greater fraction of brain and spinal cord, heart, kidney, liver, and skeletal muscle than that of the adult and aged animals. Relative to the young adult rats, the body mass of aged animals had a greater percent adipose tissue mass and a lower percent skeletal muscle and skin mass. These data demonstrate that maturation and aging have a significant effect on the distribution of cardiac output but relatively little influence on mass-specific tissue perfusion rates in conscious rats. The old-age-related alterations in cardiac output distribution to adipose and cutaneous tissues appear to be associated with the increases in percent body fat and the decreases in the fraction of skin mass, respectively, whereas the decrease in the portion of cardiac output directed to reproductive tissue of aged rats appears to be related to a decrease in mass-specific blood flow to the prostate gland.

Aging↗
PubMed1997

Measurement of cardiac output in standing horses by Doppler echocardiography and thermodilution.

Measurement of cardiac output by Doppler echocardiography were compared to simultaneous measurements by thermodilution in 9 conscious horses. In the Doppler technique, mean blood flow velocities for estimation of cardiac output were recorded from the aorta and pulmonary artery. The flow area of each vessel was calculated from the vessel diameter, measured from a 2-dimensional ultrasound image. Differences in the site and method of measuring the vessel diameter altered the estimation of cardiac output by the Doppler method. Cardiac output was modified by the i.v. infusion of 4 micrograms/kg bwt/min dopamine and 4 micrograms/kg bwt/min dobutamine and by the i.v. administration of 10 micrograms/kg bwt detomidine and 20 micrograms/kg bwt butorphanol. Doppler measurements of cardiac output correlated closely with measurement by thermodilution. Measurements from the aortic outflow correlated more closely with thermodilution, than those from the pulmonary artery (r = 0.89 and r = 0.77, respectively). Doppler measurements when the mean flow velocity was recorded from the aorta and the flow area was measured from the ascending aorta using the leading edge method. There was no significant bias between the 2 techniques when Doppler flow velocities were recorded by this method and the limits of agreement were narrow (+/- 12.26 l/min). The differences between the 2 methods increased with increasing cardiac output. Doppler echocardiography is a safe noninvasive method of measuring cardiac output in horses. The agreement between Doppler echocardiography and thermodilution in this study is similar to that reported in man and is similar to that reported between thermodilution and other techniques in man.

Analgesics↗
PubMedDate not supplied

Effects of body temperature on accuracy of continuous cardiac output measurements.

Intermittent measurement of cardiac output is routine in the critically ill surgical patient. A new catheter allows real-time continuous measurement of cardiac output. This study evaluated the impact of body temperature variation on the accuracy of these measurements compared to standard intermittent bolus thermodilution technique. This prospective study in a university hospital surgical intensive care unit included 20 consecutive trauma patients. Data were collected with pulmonary artery catheters, which allowed both continuous (COC) and bolus (COB) thermodilution measurements. The catheter was placed through either the subclavian or internal jugular vein. Measurements for COB were performed using a bolus (10 cm3) of ice-cold saline with a closed-injectate delivery system at end-expiration. Computer-generated curves were created on a bedside monitor, and the average of three measurements within 10% of one another was used as COB. COC was determined as the average of the displayed CO before and after thermodilution CO measurements. Body temperature was measured from the pulmonary artery catheter and was grouped as < or =36.5 degrees C, 36.6-38.4 degrees C, and > or =38.5 degrees C. COB and COC were compared for agreement by plotting the mean of the differences (COB - COC) between the methods. The differences were plotted against the average of each pair and analyzed with linear regression. One hundred seventy-eight paired measurements were made over a period of 1 to 3 days. CO ranged from 3.7 to 15.5 L/min. Eighty-one percent of measurements were at a temperature of 36.5-38.4 degrees C. Approximately 7% of measurements were at a temperature below 36.5 degrees C and 11.2% were in patients with a core temperature above 38.5 degrees C. Correlation between the two techniques was 0.96, 0.91, and 0.82 for temperatures of < or =36.5 degrees C, 36.6-38.4 degrees C, and > or = 38.5 degrees C, respectively. In conclusion, the COC measurements correlate well with COB in trauma patients with a core temperature < or =38.5 degrees C. The accuracy degraded at higher temperatures, which may be related to the smaller signal-to-noise ratio at elevated body temperatures.

Adult↗
PubMed1984

Noninvasive measurement of cardiac output in healthy preterm and term newborn infants.

Although values for cardiac output in the newborn infant have been reported previously, the methods utilized have been invasive. To assess if cardiac output could be determined noninvasively in the neonate, we measured mean ascending aortic blood flow velocity (VAo) in well newborns using a portable 5MHz, range gated, pulsed Doppler velocity meter. Measurements were made from a suprasternal approach in 8 preterm (mean birth weight 1718 gm; mean estimated gestation age 33.3 weeks) and 14 term (mean birthweight 3127 gm; mean EGA 39.8 weeks) healthy infants under one week of age. The internal ascending aortic systolic diameter was determined echographically and aortic cross sectional area was calculated: AAo = pi d2/4. Ascending aortic blood flow (QAo) was then computed as QAo (ml/min) = VAo (cm/sec) X AAo (cm2) X 60 (sec/min). With the exclusion of patent ductus arteriosus (PDA) and detectable intracardiac defects, QAo was taken to equal cardiac output. Flow determinations were normalized to body weight. The 8 preterm infants had a mean cardiac output of 221 +/- 56 (+/- SD) ml/min/kg. The 14 term infants had a similar mean cardiac output of 236 +/- 47 ml/min/kg. The mean cardiac output of all 22 infants was 230 +/- 50. This study establishes normal values for cardiac output determined noninvasively by the Doppler technique, in the first week of life in healthy infants. These values are similar to previously reported systemic blood flows, which were determined by cardiac catheterization and thermodilution methods in healthy newborn infants.

Aorta↗
PubMed1998

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

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

Aged↗
PubMed1997

An enhanced method for measuring cardiac output using Doppler color flow echocardiography.

An enhanced method for determining cardiac output using Doppler color flow imaging techniques to measure mitral orifice diameter was developed and validated in an experimental model and in clinical patients. In an in vitro circuit model, color jet width correlated well with actual orifice dimension from 12 to 24 mm (r = 0.99). In the clinical application, mitral valve area was calculated as a X b X pi/4 where a and b represent the width of the color flow stream in the mitral orifice just distal to the annulus in apical long-axis (short-diameter) and 4-chamber (90 degrees rotated, long-diameter) views, respectively. Cardiac output was then computed as the product of mitral valve area and time-velocity integral of transmitral flow from the same site. Cardiac output was also measured by thermodilution and conventional echocardiographic methods using diameters and time-velocity integrals from the left ventricular outflow tract. In 30 patients with nonvalvular heart disease, cardiac output measured by thermodilution ranged from 3.40 to 8.40 L/min. Cardiac output was determined in 28 of 30 patients (93%) by the Doppler color flow imaging technique; it ranged from 3.00 to 8.36 L/min and correlated well with thermodilution: y = 0.90x + 0.63, r = 0.91. Cardiac output was determined in 24 of 30 patients by the conventional left ventricular outflow method (80%). The cardiac output measured by the conventional method correlated less closely with thermodilution (r = 0.84), although there was no statistical difference in correlation coefficiencies between the 2 methods. These results indicate that the Doppler color flow imaging technique can be used to enhance the determination of cardiac output by echocardiography, particularly when the conventional method has resulted in technically inadequate recordings.

Adult↗
PubMed2006

Cardiac output measurements in off-pump coronary surgery: comparison between NICO and the Swan-Ganz catheter.

BACKGROUND: The aim of this prospective study was to compare continuous cardiac output measurements of the non-invasive cardiac output system (NICO) with the pulmonary artery catheter during off-pump coronary bypass surgery. METHODS: Twenty-two patients enrolled for off-pump coronary surgery received both a pulmonary artery catheter and a non-invasive cardiac output system for measurement of cardiac output. Data were compared by the Bland-Altman method to calculate the degree of agreement and to analyse if a significant difference existed between the two methods of cardiac output measurements. RESULTS: Perioperatively, the non-invasive cardiac output underestimated cardiac output, but postoperatively overestimated it. The limits of agreement were larger during surgery compared to the postoperative period (-3.1; +2.5 vs. -1.4; +2.2 L min(-1)). Perioperatively, cardiac output measured with the pulmonary artery catheter varied from 0.5 to 7.5 L min(-1) (mean 3.6 L min(-1)) and with the non-invasive cardiac output from 0.5 to 8.4 L min(-1) (mean 3.9 L min(-1)). Postoperatively, these were 2.5-7.7 L min(-1) (mean 4.5 L min(-1)) and 2.3-8.4 L min(-1) (mean 4.9 L min(-1)), respectively. CONCLUSION: During off-pump cardiac surgery, the non-invasive cardiac output reliably measures cardiac output and does it more rapidly than a pulmonary artery catheter and may be more useful in order to detect rapid haemodynamic changes.

Aged↗