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At least 145 records · Page 8Linked to original sources
PubMed1994

Abnormal diurnal variation of blood pressure, cardiac output, and vascular resistance in cardiac transplant recipients.

BACKGROUND: An attenuated or absent nocturnal decline in blood pressure has repeatedly been documented in cardiac transplant recipients. The present study was aimed at investigating the hemodynamic mechanism underlying this abnormality. METHODS AND RESULTS: In 23 cardiac transplant recipients (11 to 36 months after transplantation) and in 23 control subjects matched for age and 24-hour mean arterial pressure, invasive 24-hour ambulatory blood pressure was measured by means of the Oxford technique. Beat-to-beat relative values of stroke volume were determined by means of a pulse-contour method, and relative changes of cardiac output (stroke volume x heart rate) and total peripheral vascular resistance (blood pressure/cardiac output) over the 24-hour period were calculated. The nocturnal decline in blood pressure was 20 +/- 8% (mean +/- SD) in control subjects but only 5 +/- 9% (P < .001) in cardiac transplant recipients. In control subjects, the nocturnal decline in blood pressure was associated with a nocturnal fall in cardiac output of 24 +/- 13%, whereas vascular resistance compared with daytime value did not change. The small nocturnal decline in blood pressure in cardiac transplant recipients was associated with an attenuated nocturnal fall in cardiac output of 14 +/- 12% (P < .05 versus control subjects). In addition, vascular resistance compared with daytime value was increased by 9 +/- 9% (P < .05) during the night. Both in cardiac transplant recipients and in control subjects, the nocturnal changes in blood pressure were correlated with the nocturnal changes in cardiac output but not with the nocturnal changes in total peripheral vascular resistance. CONCLUSIONS: This study confirms the attenuated nocturnal fall in blood pressure in cardiac transplant recipients. Hemodynamically, this attenuated blood pressure decline is characterized by a reduced nocturnal fall in cardiac output, and it is associated with a nocturnal increase in vascular resistance.

Adolescent↗
PubMed1981

Measurement of cardiac output by the thermodilution method in rats. II. Simultaneous measurement of cardiac output and blood pressure in conscious rats.

A method is described for the simultaneous measurement of cardiac output (CO), using the thermodilution method, and arterial blood pressure in conscious unrestrained rats. For the injection of the indicator solution (ice-cold, 0.9% saline) and for the measurement of systolic and diastolic blood pressure, chronically-implanted polyethylene cathethers were used, while CO was measured transpulmonarily with a commercially available CO computer and an acutely-implanted (via caudal artery) arterial thermistor catheter. The following were observed in 10 rats at rest: a CO of 40.2 +/- 1.9 ml/min/100 g, a mean arterial blood pressure of 106 +/- 5 mmHg, a heart rate of 417 +/- 20 beats/min and a peripheral vascular resistance of 2.68 +/- 0.13 mmHG/(ml/min/100 g). After injection of the beta-adrenergic agonist isoprenaline, there was a rise in CO and heart rate, while peripheral resistance and blood pressure were lowered. Injection of the beta-receptor-blocked propranolol caused decreases in CO and heart rate, while peripheral resistance and blood pressure rose. It is concluded, that the method described here for the simultaneous measurement of CO and arterial blood pressure is suitable for the investigation of drug-induced cardiovascular effects in conscious rats.

Animals↗
PubMed1994

Oxygen Fick and modified carbon dioxide Fick cardiac outputs.

OBJECTIVE: To compare cardiac outputs estimated from the classical oxygen Fick and modified CO2 Fick methods with thermodilution cardiac output. The modified CO2 Fick cardiac output was obtained by replacing the oxygen uptake (VO2) in the Fick equation with the CO2 production (VCO2) divided by either an assumed or measured value of the respiratory exchange ratio or with an independently determined constant (Crit Care Med 1991; 19:1270-1277). DESIGN: Criterion standard study. SETTING: The medical and surgical intensive care unit (ICU) in a Veterans Affairs Medical Center. PATIENTS: A total of 17 patients (26 studies) and 11 surgical patients (13 studies), predominantly mechanically ventilated using the intermittent mandatory ventilation mode, were studied over a period of 4.3 hrs. MEASUREMENTS: A respiratory gas exchange monitor was used to measure VO2, VCO2, and respiratory exchange ratio at 3-min intervals. Calculations were performed with arterial and venous oxygen saturations measured with both a laboratory cooximeter and bedside pulse and venous reflectance oximeters. In the oxygen Fick method, cardiac output was calculated from VO2 together with arterial and venous oxygen saturations. In the modified CO2 Fick methods, cardiac output values were calculated from arterial and venous oxygen saturations with VCO2, divided by either: a) an assumed value of the respiratory exchange ratio equal to 0.8 for all patients (method 1); b) the patient's measured value of the respiratory exchange ratio (method 2); or c) a constant, determined from an initial, simultaneous measurement of thermodilution cardiac output, VCO2, and oximetry saturations. Data were examined by linear regression analysis and bias and precision calculations. MAIN RESULTS: Thermodilution cardiac output was more related to cardiac outputs calculated with the 3 modified CO2 Fick methods than to the oxygen Fick cardiac output. Thermodilution cardiac output was closely related to the modified CO2 Fick cardiac output calculated via method 3. For this method, with pulse and venous reflectance oximetry saturations, linear regression yielded an r2 = .85, a standard error of the estimate of 0.88 L/min (n = 111) and a bias and precision of 0.11 and 0.97 L/min, respectively. Thermodilution cardiac output was less closely related to oxygen Fick cardiac output, which, when calculated with pulse and venous reflectance oximetry saturations, yielded an r2 = .50, a standard error of the estimate of 1.47 L/min (n = 128), and a bias and precision of 0.01 and 1.85 L/min, respectively. CONCLUSIONS: We conclude from this study that thermodilution cardiac output is more closely related to cardiac output calculated from modified CO2 Fick methods than to oxygen Fick cardiac output. Since cardiac output calculated with the modified CO2 Fick method 3 obviates the difficulties associated with measuring VO2 accurately and requires neither an assumption of nor measurement of the respiratory exchange ratio, method 3 may prove to be clinically useful for continuous cardiac output monitoring via oximetry in ICU patients.

Adult↗
PubMed1986

Continuous noninvasive monitoring of cardiac output with esophageal Doppler ultrasound during cardiac surgery.

Esophageal Doppler ultrasonography offers a continuous and noninvasive alternative to standard thermodilution cardiac output monitoring. A total of 372 simultaneous measurements of Doppler and thermodilution cardiac output were compared in 16 patients undergoing cardiac surgery. In addition, echocardiographic aortic diameter measurement, necessary for Doppler calibration, was compared with direct surgical measurement in 23 patients. Echocardiographic aortic measurement was often time consuming and correlated poorly (r = 0.31) with surgical measurement. On the other hand, Doppler cardiac output was determined easily and accurately tracked thermodilution cardiac output (R2 = 0.95, common slope coefficient 1.050, by multiple linear regression). Furthermore, Doppler cardiac output was more reproducible, showing less short-term variability than thermodilution cardiac output. The esophageal Doppler technique allows cardiac output monitoring in patients for whom invasive monitoring is not warranted.

Adult↗
PubMed2005

Continuous cardiac output monitoring with pulse contour analysis: a comparison with lithium indicator dilution cardiac output measurement.

OBJECTIVE: Pulse contour analysis can be used to provide beat-to-beat cardiac output (CO) measurement. The current study sought to evaluate this technique by comparing its results with lithium dilution CO (LiCO) measurements. DESIGN: Prospective, observational study. SETTING: Surgical intensive care unit. PATIENTS: Twenty-two patients after cardiac or major noncardiac surgery. MEASUREMENTS: After initial calibration of the pulse contour CO (PCO) method, CO was measured by PCO and by LiCO methods at 4, 8, 16, and 24 hrs. Recalibration of PCO was performed every 8 hrs. The systemic vascular resistance and dynamic response characteristics of the arterial catheter-transducer system were measured at each time point to determine whether these influenced the agreement between PCO and LiCO methods. MAIN RESULTS: There was an excellent correlation between methods (r = .94). Bias was small (-0.005 L/min), and clinically acceptable limits of agreement were demonstrated between techniques. Although many catheter-transducer systems had poor dynamic response characteristics, this did not influence the level of agreement between the two techniques. An increase in systemic vascular resistance between two time points did tend to cause overestimation of LiCO by the PCO. CONCLUSIONS: PCO measurement compared well with the lithium dilution method and can be considered an accurate technique for measuring beat-to-beat CO with limited risk to the patient.

Cardiac Output↗
PubMed2004

[Anesthetic management for removal of a giant ovarian tumor by monitoring transesophageal Doppler cardiac output].

Transesophageal Doppler cardiac output was monitored in two cases for removal of a giant ovarian tumor. In case 1, cardiac output (CO) increased following the drainage of the tumor, and CO decreased following blood loss. In case 2, CO increased following the removal of the tumor, and remained stable because of small blood loss. Cardiovascular parameters changed remarkably with the drainage of tumors and blood loss. Therefore, noninvasive Doppler cardiac output monitor was useful for rapid estimation of cardiovascular changes.

Adult↗
PubMed1984

Reconsideration of heart rate-cardiac output relationships and resting cardiac function in patients with brady-arrhythmias.

Different types of heart rate (HR)-cardiac output (COP) relationships were compared with their clinical features and hemodynamic findings in 56 patients with brady-arrhythmias (BA). HR was raised by increments of 10 beats per minute (bpm) at 3 min intervals, from spontaneous rates to 100 or 110 bpm by right ventricular pacing. Cardiac and left ventricular (LV) functions at BA were evaluated by intra-cardiac pressures, COP measured by the thermo-dilution method and echocardiographic data. HR-COP relationships were divided into the following 3 types: 24 patients of flat (F), 18 of peaked (P) and 14 of increased (I) type. There were more patients with complete atrio-ventricular block, particularly His-ventricular block, and cardiomyopathic patients with the "P" type than with the other types. Cardiac index, stroke index, stroke work index and systemic vascular resistance were greater in "I", but these differences were not significant. LV peak systolic pressure (LVSP) and end-diastolic pressure (EDP) in "I" increased more than in "F". EDP, LV end-diastolic and end-systolic dimension (ESD) in "P" increased more than in "F". Systolic excursion and LVSP/ESD ratio in "I" increased more than in the other types. Heart failure prior to implantation of pacemaker (PM) and post-PM occurred more frequently in "P". "F" and "I" patients showed comparatively good clinical courses after PM. Thus, cardiac and LV function during BA are maintained in "F" and are impaired in "P", as reported previously. On the other hand, cardiac functions are maintained in "I" as they are in "F", mainly due to contributions of the Frank-Starling mechanism and partly due to maintenance or slight augmentation of contractility.

Adolescent↗
PubMed1976

Cardiac output measurement by thermodilution during cardiac operations.

Measurement of cardiac output by the thermodilution (COTD) technique through a flow-advanced pulmonary artery catheter is simple, reliable, and practical at the bedside. Rapid repeat determinations are possible, facilitating dynamic description of myocardial performance through construction of ventricular function curves. Replicate determinations of cardiac output indicate that the thermodilution method is more accurate than the indocyanine green technique. Examples of the clinical application of COTD in cardiac surgical patients are provided.

Animals↗