OBJECTIVES: To determine the amount of spontaneous variability of cardiac output over time in critically ill patients, and to determine the effect of mechanical ventilation on cardiac output variability over time. DESIGN: Case series. SETTING: Medical intensive care unit in a Veterans Affairs Medical Center. PATIENTS: Twenty-two patients with indwelling pulmonary artery flotation catheters were studied. Two patients were studied twice. INTERVENTIONS: During a 1-hr time period in which no interventions were required or made, thermodilution cardiac output was determined at baseline and then every 15 mins for 1 hr. At each time point, five individual cardiac output measurements were made and a mean was computed. The covariables of heart rate, respiration rate, mean arterial pressure, mean pulmonary arterial pressure, pulmonary artery occlusion pressure, and temperature were also recorded at each time point. MEASUREMENTS AND MAIN RESULTS: The variability of the five cardiac output measurements made at each time point was expressed by calculating for each patient a coefficient of variation of the measurements. The overall mean coefficient of variation of the measurements was 5.8%. The variability of the cardiac output measurements over time was expressed by calculating for each patient a coefficient of variation over time. The overall mean coefficient of variation over time was 7.7%. A subgroup of 15 "covariable stable" patients (defined as those patients with covariables within +/- 5% of the mean covariable values during the hour) had a mean coefficient of variation over time of 6.4%, whereas "covariable unstable" patients (with > +/- 5% changes in any covariable) had a mean coefficient of variation over time of 9.9% (p < .05). Patients breathing spontaneously had a mean coefficient of variation over time of 10.1%, whereas mechanically ventilated patients had a mean coefficient of variation over time of 6.3% (p < .05). CONCLUSIONS: The spontaneous variability of cardiac output should be considered when interpreting two cardiac output determinations made at separate times. Due to spontaneous variability alone, a patient with a baseline cardiac output of 10.0 L/min would be expected (95% confidence interval) to have a cardiac output range of 9.2 to 10.8 L/min if covariables were stable, and a range of at least 8.8 to 11.2 L/min if covariables were unstable. Patients who were mechanically ventilated displayed less variability than patients who were breathing spontaneously.
OBJECTIVES: To determine the amount of spontaneous variability of cardiac output over time in critically ill patients, and to determine the effect of mechanical ventilation on cardiac output variability over time. DESIGN: Case series. SETTING: Medical intensive care unit in a Veterans Affairs Medical Center. PATIENTS: Twenty-two patients with indwelling pulmonary artery flotation catheters were studied. Two patients were studied twice. INTERVENTIONS: During a 1-hr time period in which no interventions were required or made, thermodilution cardiac output was determined at baseline and then every 15 mins for 1 hr. At each time point, five individual cardiac output measurements were made and a mean was computed. The covariables of heart rate, respiration rate, mean arterial pressure, mean pulmonary arterial pressure, pulmonary artery occlusion pressure, and temperature were also recorded at each time point. MEASUREMENTS AND MAIN RESULTS: The variability of the five cardiac output measurements made at each time point was expressed by calculating for each patient a coefficient of variation of the measurements. The overall mean coefficient of variation of the measurements was 5.8%. The variability of the cardiac output measurements over time was expressed by calculating for each patient a coefficient of variation over time. The overall mean coefficient of variation over time was 7.7%. A subgroup of 15 "covariable stable" patients (defined as those patients with covariables within +/- 5% of the mean covariable values during the hour) had a mean coefficient of variation over time of 6.4%, whereas "covariable unstable" patients (with > +/- 5% changes in any covariable) had a mean coefficient of variation over time of 9.9% (p < .05). Patients breathing spontaneously had a mean coefficient of variation over time of 10.1%, whereas mechanically ventilated patients had a mean coefficient of variation over time of 6.3% (p < .05). CONCLUSIONS: The spontaneous variability of cardiac output should be considered when interpreting two cardiac output determinations made at separate times. Due to spontaneous variability alone, a patient with a baseline cardiac output of 10.0 L/min would be expected (95% confidence interval) to have a cardiac output range of 9.2 to 10.8 L/min if covariables were stable, and a range of at least 8.8 to 11.2 L/min if covariables were unstable. Patients who were mechanically ventilated displayed less variability than patients who were breathing spontaneously.
Authors: J Y Lefrant; P Bruelle; J Ripart; F Ibanez; G Aya; P Peray; G Saïssi; J E de La Coussaye; J J Eledjam Journal: Can J Anaesth Date: 1995-11 Impact factor: 5.063
Authors: Tobias Täger; Hanna Fröhlich; Jennifer Franke; Karen Slottje; Andrea Horsch; Dietmar Zdunek; Georg Hess; Andreas Dösch; Hugo A Katus; Frank H Wians; Lutz Frankenstein Journal: ESC Heart Fail Date: 2015-06-15
Authors: Bart Hiemstra; Ruben J Eck; Geert Koster; Jørn Wetterslev; Anders Perner; Ville Pettilä; Harold Snieder; Yoran M Hummel; Renske Wiersema; Anne Marie G A de Smet; Frederik Keus; Iwan C C van der Horst Journal: BMJ Open Date: 2017-09-27 Impact factor: 2.692