Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CARDIAC OUTPUT”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,315 records · Page 73Linked to original sources
PubMed1993

Continuous negative extrathoracic pressure and cardiac output--a pilot study.

Continuous negative extrathoracic pressure (CNEP) has been recently reintroduced as therapy for respiratory failure. To determine its effects on cardiac output a pilot study was performed in ten patients aged 2 months-3 years (median 4 months). All had chronic respiratory failure (seven with bronchopulmonary dysplasia). Five were breathing spontaneously and five were intubated and undergoing intermittent positive pressure ventilation. Transcutaneous oxygen saturation and PCO2, together with ECG were continuously monitored. Pulmonary artery blood flow velocity was measured non-invasively using pulsed wave Doppler. The 95% confidence intervals for the changes with and without CNEP in spontaneously breathing and ventilated patients showed no statistically significant changes in heart rate, O2 saturation, transcutaneous PCO2 or cardiac output. This study shows that the use of CNEP, administered in a tank respirator, does not lead to large changes in cardiac output.

Blood Flow Velocity↗
PubMed1975

Measurement of cardiac output by thermal dilution in infants and children.

The accuracy of the thermal dilution technique for measuring cardiac output in infants and children has been assessed by comparison with the direct Fick technique. Satisfactory correlation between the two methods has been demonstrated, and it is concluded that a commercially available monitor can be used to determine cardiac output by thermal dilution in acutely sick infants and children. The volume of injectate should be selected according to the weight of the child, and the value displayed by the monitor should be adjusted by the appropriate fraction.

Acute Disease↗
PubMed2001

Non-invasive cardiac output determination: comparison of a new partial-rebreathing technique with thermodilution.

This study compares a derivative Fick technique using carbon dioxide (CO2) with the thermodilution pulmonary artery catheter (PAC), for determination of cardiac output (CO). Subjects were sedated, mechanically ventilated adults following elective cardiac surgery Microprocessor controlled deadspace activation and side-stream capnography in a ventilator circuit enabled calculation of CO (CO(CO2)) every four minutes. Thermodilution CO (CO(TD)) was performed as clinically indicated and at 20-minute intervals. Simultaneous CO(TD)/CO(CO2) pairs were recorded from time of admission to ICU for a minimum period of two hours for each patient. There were 358 CO(TD)/CO(CO2) pairs recorded from 41 patients. Cardiac output measurements ranged from 2. 7 to 10.6 l/min. The bias (Bland-Altman) was 0.050 l/min (95% CI -0.024 to 0.125 l/min). The 95% limits of agreement were -1.354 to 1.455 l/min. This simple, non-invasive partial-rebreathing technique is a valid alternative to thermodilution for cardiac output determination in sedated, mechanically ventilated patients. There are significant implications for improved safety, reduced complexity and reduced cost in anaesthesia and intensive care.

Adult↗
PubMed2000

Cardiac output measured by lithium dilution and transpulmonary thermodilution in patients in a paediatric intensive care unit.

OBJECTIVE: To compare the results of cardiac output measurements obtained by lithium dilution and transpulmonary thermodilution in paediatric patients. DESIGN: A prospective study. SETTING: Paediatric intensive care unit in a university teaching hospital. PATIENTS: Twenty patients (age 5 days-9 years; weight 2.6-28.2 kg) were studied. INTERVENTIONS: Between two and four comparisons of lithium dilution cardiac output (LiDCO) and transpulmonary thermodilution (TPCO) were made in each patient. MEASUREMENTS AND RESULTS: Results from three patients were excluded: in one patient there was an unsuspected right-to-left shunt, in two patients there was a problem with blood sampling through the lithium sensor. There were 48 comparisons of LiDCO and TPCO in the remaining 17 patients over a range of 0.4-6 l/min. The mean of the differences (LiDCO-TPCO) was -0.1 +/- 0.3 (SD) l/min. Linear regression analysis gave LiDCO = 0.11 + 0.90 x TPCO l/min (r2 = 0.96). There were no adverse effects in any patient. CONCLUSIONS: These results suggest that the LiDCO method can be used to provide safe and accurate measurement of cardiac output in paediatric patients. The method is simple and quick to perform, requiring only arterial and venous catheters, which will already have been inserted for other reasons in these patients.

Age Factors↗
PubMed2000

Enhanced cardiac thermal dilution analysis for cardiac output, volumes, stroke volumes, and regurgitation rates--sensitivity analysis using digital simulation.

Cardiac output is measured by placing a double lumen catheter with a thermistor on the tip through the right ventricle into the pulmonary artery, injecting cold saline into the right atrium, and integrating the resulting pulmonary artery temperature profile. If a similar procedure is performed with thermistors located in the right atrium, right ventricle, and pulmonary artery, the resulting temperature curves are determined by the known or easily measured quantities: injectate temperature, injectate volume, heart rate, systolic time interval, body temperature, and time in the cardiac cycle at which injection begins and the unknown quantities: right atrial, right ventricular, pulmonary artery mean and stroke volumes, inflow and outflow valve regurgitation rates, and cardiac output. A digital computer program using a lumped parameter model has been developed to use these quantities to produce thermal dilution curves and optimize the fit of the model curves to the temperature curves from the thermal dilution measurement to determine the unknown quantities. The program is used to investigate the effects of measuring system time constant, heat transfer, and noise on the accuracy of these measurements. The results indicate that the method is practical.

Cardiac Output↗
PubMedDate not supplied

Levosimendan for low cardiac output: a pediatric experience.

This was a retrospective observational study in a pediatric intensive care unit, in which 19 patients received levosimendan. There were no adverse events attributable to levosimendan and no instances where the clinical condition worsened after administration. Arterial lactate levels decreased significantly following levosimendan administration during cardiopulmonary bypass for anticipated low cardiac output. In those with established low cardiac output, trends toward improved hemodynamics were seen, with heart rate reduction, an increase in mean blood pressure, a reduction in arterial lactate, and reduced conventional inotrope use. Levosimendan was safely used in a small number of pediatric patients with established low cardiac output state who demonstrated improved hemodynamics and tissue perfusion, with a tendency to reduced conventional inotrope usage, and this warrants its evaluation as an inotrope in the pediatric population.

Adolescent↗
PubMed1988

The effects of endothelium-dependent vasodilators on cardiac output and their distribution in the anaesthetized rat: a comparison with sodium nitroprusside.

1. The effects of sodium nitroprusside, acetylcholine and bradykinin on cardiac output and its distribution were studied in the anaesthetized, vagotomised rat preparation by use of 113Sn-labelled microspheres. 2. All three vasodilators lowered peripheral arterial blood pressure, but only bradykinin significantly reduced total peripheral resistance without reducing cardiac output. Bradykinin caused tachycardia, but this was offset by a reduction in stroke volume. These effects of bradykinin were not altered by indomethacin (4 mg kg-1). Acetylcholine and sodium nitroprusside both caused significant (P less than 0.05) reductions in stroke volume and cardiac output. 3. Bradykinin reduced vascular resistance in the liver, stomach, small intestine, large intestine, pancreas/mesentery, epididimides, skeletal muscle and fat. These responses were not affected by indomethacin, whereas, the reduction in vascular resistance in the brain induced by bradykinin was abolished by indomethacin. 4. Acetylcholine caused a reduction in renal vascular resistance, where bradykinin had no effect. However, acetylcholine did not cause any haemodynamic changes in the bradykinin-sensitive intestinal vasculature. 5. Acetylcholine caused vasoconstriction in the coronary and epididymal vasculature. Bradykinin in the presence of indomethacin induced vasoconstriction in the skin. 6. In conclusion, the data show that, with the possible exception of the brain and the skin, the vasodilator actions of bradykinin can adequately be transduced (presumably by endothelium-derived relaxing factor, EDRF) in the absence of prostacyclin synthesis. Additionally, these results indicate that the vasculature of the stomach, pancreas/mesentery, epididimides and skeletal muscle are equally sensitive to both acetylcholine and bradykinin, whereas the kidneys showed selectivity towards acetylcholine and the intestines towards bradykinin. These results may indicate differential receptor populations.

Acetylcholine↗
PubMed1997

A simple method for the continuous noninvasive estimate of cardiac output using the Maxima breathing system. A pilot study.

The Maxima is a new breathing system which makes it possible to monitor cardiac output (Q) noninvasively and to follow trends continuously. When used as a rebreathing system in controlled ventilation, the Maxima selectively eliminates alveolar gas and no fresh gas (VF) is eliminated. Without the need for a mixing chamber, eliminated CO2 (FeCO2) may be measured directly. With steady state conditions, and assuming a respiratory quotient of 1, carbon dioxide production (VCO2) = VF x FeCO2. The indirect Fick principle applied to CO2 exchange (Q = VCO2/ venous-to-arterial CO2 content difference (CaCO2-CvCO2) may be modified to Q = VF x FeCO2/(CaCO2-CvCO2). If VF in the breathing system is adjusted so that FeCO2 is equal to CaCO2-CvCO2, then Q = VF. It was found that, in the presence of a normal haemoglobin (13.3 g.dl-1), Q = VF when VF was adjusted to achieve an FeCO2 value of approximately 4.1%. Cardiac output estimates were compared with those obtained using a thermodilution technique in five patients undergoing coronary artery bypass grafting and in four patients with septicaemia in the ICU. Cardiac outputs were estimated from 1. VCO2 measurements and then 2. VCO2 and haemoglobin (Hb). The result of 28 measurements on nine patients with methods 1. and 2. respectively yielded a correlation with thermodilution measurements: coefficient r = 0.91 and 0.94 with a bias of -10.5% and -0.05% and an accuracy of 14% and 9%.

Capnography↗
PubMed1976

The Bcg for measuring cardiac output in a California Gray Whale.

Resting cardiac output can be predicted reasonably accurately from body mass in man and other mammals. We measured the stroke volume of a 4,500-kg whale and found that Iberall's formula holds true even when body mass is very large. In addition, the Bcg acceleration trace and cardiac indices were remarkably similar to those of 20-gram and 70-kg mammals, mouse and man.

Animals↗
PubMed1982

Borderline hypertension and obesity: two prehypertensive states with elevated cardiac output.

Systemic, renal and splanchnic hemodynamics, intravascular volume, circulating catecholamine levels and plasma renin activity were compared in 39 patients with borderline hypertension and 28 normotensive subjects, who were less than 5% (n = 42, lean patients) or more than 40% overweight (n = 25, obese patients). Lean borderline hypertensive patients had greater cardiac output (p less than 0.05), heart rate (p less than 0.01) and renal blood flow (p less than 0.05); cardiopulmonary redistribution of intravascular volume (p less than 0.05); and higher circulating norepinephrine levels (p less than 0.05). Obese normotensive subjects also showed an increased cardiac output (p less than 0.005), stroke volume (p less than 0.01), left ventricular stroke work (p less than 0.05), and renal blood flow (p less than 0.05) (but not respective indexes), but intravascular volume was expanded (p less than 0.05) without redistribution and circulating catecholamine levels were normal. Obese borderline hypertensive patients had hemodynamic characteristics similar to those of obese normotensive subjects except for an increased peripheral resistance (p less than 0.05). The data indicate that although both populations have an increased cardiac output, the lean borderline hypertensive patients have signs of enhanced adrenergic activity as evidenced by higher circulating catecholamine levels and heart rate with blood volume translocation to the cardiopulmonary circulation. In contrast, the obese subjects (whether normotensive or borderline hypertensive), who also have increased cardiac output, seem to have normal adrenergic activity and an expanded intravascular volume without cardiopulmonary redistribution.

Adult↗
PubMed1984

Cardiac output and regional blood flows during hypoxaemia in unanaesthetized newborn lambs.

There is limited information available regarding the effects of hypoxemia on cardiac output and the distribution of blood flow and oxygen delivery in unanaesthetized newborns of any species. We measured these variables in 12 unanaesthetized newborn lambs during a control period and during 50% and 75% reductions in aortic blood oxygen content which were produced by placing each lamb in an environment of 8-10% and 5-6% oxygen, respectively. 1-2% carbon dioxide was added to the gas mixture and there were no significant changes in aortic blood PCO2 or pH. Hypoxaemia was associated with a 15-20% increase in cardiac output but total somatic oxygen delivery decreased. Cerebral, myocardial, adrenal and diaphragmatic blood flows increased and their oxygen deliveries were not diminished. Oxygen deliveries to the spleen, kidneys, gastrointestinal tract and carcass decreased when aortic blood oxygen content was reduced. This study demonstrates that the newborn lamb has a limited ability to increase its cardiac output during hypoaxemia, but that oxygen deliveries to the heart, brain, adrenals and diaphragm are maintained in association with a redistribution of blood flow.

Animals↗
PubMed1991

Peripheral circulatory control of cardiac output in diabetic rats.

Diabetes is believed to be associated with impaired systolic and diastolic function of the heart; however, some investigators have found that diabetic rats have increased cardiac output. We investigated changes in the peripheral circulation that could account for an increased cardiac output in diabetic rats (n = 30), 4 wk after a single tail vein injection of streptozotocin (60 mg/kg), and age-matched control rats (n = 31). Compared with controls, diabetic rats exhibited decreased (P less than 0.05) mean arterial pressure, characteristic aortic impedence, and total peripheral resistance; however, cardiac index and stroke volume index were increased. Aortic compliance, mean circulatory filling pressure, central venous pressure, pressure gradient for venous return, and venous compliance were unchanged in the diabetic rats compared with control. Baseline left ventricular end-diastolic pressure and end-diastolic volume were increased in the diabetic rats. Following a volume load of 30 ml/kg, cardiac index and stroke volume index increased less in the diabetic than in the control rats (35 vs. 102% and 69 vs. 105%, respectively). Thus, even with impaired systolic function, cardiac output is increased or maintained in diabetic rats because of the combination of decreased afterload and maintenance of preload.

Animals↗
PubMed2005

[Comparison of cardiac output measured by pulseCO and that by vigilance during inferior vena cava clamping].

BACKGROUND: PulseCO is a low invasive apparatus to measure cardiac output continuously from arterial pulse waveform (PulseCCO). It is thought that the accuracy of PulseCCO measurement is clinically acceptable with stable hemodynamics. We measured and evaluated PulseCCO during inferior vena cava clamp (IVC clamp). METHODS: Anesthesia was induced with propofol and vecuronium. After induction, an arterial catheter and a pulmonary artery catheter were inserted, and anesthesia was maintained with general anesthesia and continuous epidural anesthesia. At first IVC was clamped for five minutes and after an interval of five minutes IVC was clamped again. During IVC clamp maneuver, we measured PulseCCO and continuous cardiac output with Vigilance (VigilanceCCO). RESULTS: At the time of the first IVC clamp and declamp, VigilanceCCO was unchanged, but Pulse CCO showed a marked change. After the second IVC clamp, both PulseCCO and VigilanceCCO decreased, but the change was slower with VigilanceCCO. CONCLUSIONS: With IVC clamp maneuver which is thought to cause rapid change of cardiac output, PulseCCO showed more rapid change in comparison with VigilanceCCO. In the state where hemodynamics change rapidly, PulseCO can be a more useful monitor.

Aged↗
PubMed1993

Cardiac output and regional hemodynamics during recurrent seizures in rats.

Altered cardiovascular function in status epilepticus may contribute to mortality and morbidity in patients. We investigated changes in cardiac output and regional hemodynamics during 2 h of recurrent PTZ-induced seizures in anesthetized, paralyzed rats using radioactive microspheres, thermodilution methods, and the pulsed Doppler technique. Cardiac output fell 30-60% during recurrent seizures in 17 of 27 animals. The fall in cardiac output was sudden in onset and occurred primarily in association with seizures accompanied by prolonged increases in MABP but no change in central venous pressure. Total peripheral resistance (TPR) rose during early seizures in association with vasoconstriction of renal and certain splanchnic vascular beds. Ictal increases in TPR became attenuated during late seizures, due to failure of renal and splanchnic beds to constrict. Therefore, derangements in both cardiac and vascular function occur during late seizures. These derangements may contribute to both cerebral hypoperfusion and sudden death in status epilepticus.

Animals↗
PubMed1987

Relationship between mean airway pressure, cardiac output, and organ blood flow with normal and decreased respiratory compliance.

We investigated the relation between blood flow and mean airway pressure in two groups of anesthetized newborn piglets. The first group had normal respiratory compliance; the second group had pulmonary surfactant depleted by repeated saline lavage, which decreased static respiratory compliance by 42%. In the normal group, cardiac output decreased linearly from 292 +/- 43 mL/min/kg at 5 cm H2O airway pressure to 134 +/- 37 ml/min/kg at 20 cm H2O airway pressure, a drop of 43% (r2 = 0.79). Blood flow to the heart, kidney, and intestines had a similar decline, but brain, hepatic artery, and adrenal flow were constant. Mean arterial blood pressure did not decrease significantly until the highest airway pressure was reached, whereas sagittal sinus pressure increased as mean airway pressure increased. In contrast, the surfactant-depleted group maintained cardiac output up to a mean airway pressure of 15 cm H2O. At 20 cm H2O, cardiac output fell to 40% of the original value. Blood flow to the heart and kidneys fell at a mean airway pressure of 20 cm H2O; intestinal blood flow decreased beginning at 10 cm H2O. As in the normal piglets, brain, hepatic arterial, and adrenal blood flow were not affected by increasing ventilation pressure. Our data show that positive pressure ventilation in the neonate has important cardiovascular effects that are blunted when respiratory compliance is decreased. More important, because cardiac output decreased prior to a significant decline in arterial blood pressure, these data suggest that in a clinical setting considerable cardiovascular alterations can occur before a decline in arterial blood pressure is detected.

Airway Resistance↗
PubMed2004

Non-linear cardiac output dynamics during ramp-incremental cycle ergometry.

Published literature asserts that cardiac output (Q(.) = V(.) >O(2)x1/C((a-v))O(2)) increases as a linear function of oxygen uptake with a slope of approximately 5-6 during constant work rate exercise. However, we have previously demonstrated that C((a-v))O(2) has a linear relationship as a function of V(.)O(2) during progressively increasing work rate incremental exercise. Therefore, we hypothesized that Q(.) may indeed have a non-linear relationship with respect to V(.)O(2) during incremental, non-steady state exercise. To investigate this hypothesis, we performed five maximal progressive work rate exercise studies in healthy human subjects. Q(.) was determined every minute during exercise using measured breath-by-breath V(.) >O(2), and arterial and pulmonary artery measurements of PO(2), hemoglobin saturation, and content. Q(.) was plotted as a function of V(.) >O(2) and the linear and non-linear (first order exponential and hyperbolic) fits determined for each subject. Tests for linearity were performed by assessing the significance of the quadratic terms added to the linear relation using least squares estimation in linear regression. Linearity was inadequate in all cases (group P<0.0001). We conclude that cardiac output is a non-linear function of V(.)O(2 )during ramp-incremental exercise; the pattern of non-linearity suggests that while the kinetics of Q(.) > are faster than those of V(.) >O(2) they progressively slow as work rate (and V(.) >O(2)) increases.

Adult↗
PubMed1989

Accuracy of cardiac output measured by continuous wave Doppler echocardiography during dynamic exercise testing in the supine position in patients with coronary artery disease.

To estimate the accuracy of cardiac output measured by continuous wave Doppler echocardiography from the suprasternal notch and the utility of this method for evaluating left ventricular function during dynamic exercise, simultaneous thermodilution and Doppler cardiac output were measured in 34 patients with coronary artery disease during multistage ergometer exercise in the supine position. Cardiac output was measured at rest and during each stage of exercise. Twenty-five of the 34 patients whose thermodilution curves were adequate for analysis were studied during exercise. The correlation coefficient for the two methods was 0.85 at rest and 0.84 during exercise. Differences between the two methods were not significant at rest but were significant during exercise, with the thermodilution method giving the higher values. Underestimation by the Doppler method is probably due to technical problems and changes in aortic diameter during exercise. The 25 patients were classified into two groups according to pulmonary artery wedge pressure at peak exercise. There were 11 patients in Group 1 pressure (greater than or equal to 20 mm Hg at peak exercise) and 14 in Group 2 pressure (less than 20 mm Hg at peak exercise). There were significant differences in the change in cardiac index and in peak aortic velocity from rest to peak exercise between the two groups. A significant linear correlation between the percent change in peak aortic velocity and in pulmonary artery wedge pressure from rest to peak exercise was observed (r = -0.66, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Continuous Fick cardiac output measurement during inhalation anesthesia].

A computer based system that continuously monitors cardiac output (CO) and the other hemodynamic variables has been developed. Fick CO was calculated every 10 sec on breath by breath basis. The arterio-venous oxygen content difference was measured by a combination of a pulse oximeter and a fiberoptic oximeter. Oxygen consumption was calculated by a direct measurement of respiratory gas exchange: airway flow was obtained from a Servo 900C ventilator and the instantaneous oxygen concentration was measured with a paramagnetic oxygen sensor. This system enabled us to use inhalation anesthetics which were avoided during Fick CO measurement with a zirconium oxygen sensor. Fick CO was compared to electromagnetic CO (EMCO) in 5 dogs anesthetized with enflurane. A total of 198 simultaneous data of CO measurements had a range from 0.5 to 2 l/min. Simultaneous measurements of Fick CO and EMCO showed a good correlation (r = 0.97), and a regression equation was: Y = X + 0.029. Fick CO was compared with cardiac output measured by a conventional thermodilution method (TDCO) in 12 patients anesthetized with either enflurane or isoflurane. A total of 207 simultaneous CO measurements ranged from 3 to 10.2 l/min. Regression analysis of 207 paired Fick CO and TDCO values showed a good correlation (r = 0.94), and a regression equation (Fick CO = TDCO-0.28). The "limits of agreement" (mean difference +/- 2 SD of bias) were within +/- 1.12 l/min, which could be acceptable for clinical settings. When hemodynamic states were abruptly changed by an intravenous administration of isoproterenol, Fick CO reached 90% of EMCO change within 30 sec. The author concludes that this system provides virtually continuous hemodynamic analyses and facilitates more sophisticated circulatory control of the patients within a limited fluctuation.

Anesthesia, Inhalation↗