Cardiac Output Measurements Research Articles

Abstract 13592: Gender Related Divergences in Cardiac and Vascular Function With Age

Introduction: Heart failure with preserved ejection fraction (HFpEF) is a disease of advanced aging that disproportionately affects women. Diastolic function changes with age and it is unknown if gender-related differences in progression exist. Understanding ages at which parameters of vascular and diastolic function diverge may provide insight into the differential risk of HFpEF between genders. Methods: Sedentary but healthy non-obese subjects aged 20-90 (n=178, 58% female; avg age 56 ± 13 yrs) underwent measures of pulmonary capillary wedge pressure (PCWP; right heart catheterization), blood pressure and cardiac output (acetylene rebreathe). Diastolic function was assessed by Doppler echocardiogram. A generalized linear model was used to estimate effects of age for each measured hemodynamic parameter as a function of gender. Results: Across age, women had higher systolic blood pressure (SBP) (age*gender p=0.025, age p<0.001) and total peripheral resistance (TPR) (age*gender p=0.053, age p<0.001). Changes in TPR were apparent at age 26 while SBP diverged at age 55. (Figure) Women had slower early diastolic recoil (e’) (age*gender p<0.001) starting at age 55. While E wave velocity was lower in women, age-related decline was similar to men. E/e’ was higher in women (age*gender p=0.007) and diverged at a young age (28). PCWP declined with age similarly in both men and women. Systolic velocity (s’) declined in early middle age (42) in women (age*gender p=0.007, age p=0.002). Conclusions: Women experience greater changes in cardiac and vascular function with age than men. The age at which these parameters diverge differs, with evidence for decline in vascular function and cardiac contractility occurring at young ages in women while changes in SBP and diastolic recoil occur after age 55. Understanding lifestyle and hormonal factors that influence these differences may help elucidate HFpEF risk factors that are modifiable and serve as a target for therapy.

Doppler echocardiography in a healthy, non-sedated Southern Sea Lion (Otaria flavescens) - a preliminary approach about the feasibility and clinical utility.

Echocardiography is commonly used in veterinary clinical practice for many species but is not as easily applied in non-sedated marine mammals. Additionally, Doppler echocardiography provides further information on hemodynamics, estimation of cardiac output, characterization of flow patterns, and diastolic function. However, its applications in marine mammals have not been as widely explored either. The present report aimed to characterize the left ventricle structure and function of the Southern Sea Lion (Otaria flavescens) through a Doppler echocardiography study. Data were obtained from a healthy animal trained for different veterinary examination routines. This communication constitutes the first report of Doppler echocardiography with stroke volume, and cardiac output measurement in pinnipeds, and the first report of measurement of myocardial performance index in aquatic mammals. This data brought initial information about in vivo structure and function of the heart of the Southern Sea Lion that can be safely and effectively evaluated with the use of transthoracic Doppler echocardiography. Our data have both clinical and research implications for future studies evaluating diseases of the cardiopulmonary system in pinnipeds, and cardiovascular physiology investigation in diving mammals.

Does veno-arterial carbon dioxide gradient provide an adequate estimation of cardiac index in pulmonary hypertension?

Pulmonary hypertension (PH) management is dependent on cardiac output (CO) assessment. The gold standard Fick method for CO and cardiac index (CI) measurement is not widely available. An accessible and reliable method for CO/CI estimation is needed not only in catheterization labs but also in other environments such as the intensive care unit, where pulmonary artery catheters are less likely to be used. We hypothesized that veno-arterial carbon dioxide gradient (PvaCO2) is a reliable surrogate for Fick CI in patients with PH. A single-centre retrospective analysis of patients with PH who underwent direct Fick CI (DFCI) measurement during right heart catheterization. The primary outcome was correlation between PvaCO2 and DFCI. To assess the agreement between central and mixed venous CO2 values, a separate prospective cohort of patients was analysed. Data from 186 patients with all haemodynamic types of PH were analysed. PvaCO2 moderately correlated with Fick CI, R = -0.51 [95% confidence interval (CI): -0.61, -0.39]. A higher PvaCO2 was associated with an increased risk of CI < 2.5 L/min/m2 (odds ratio: 1.88, 95% CI: 1.55, 2.35). Low thermodilution CI with normal veno-arterial carbon dioxide gradient values was associated with a thermodilution underestimation of Fick CI. In the prospective analysis of 32 patients, central venous CO2 overestimated mixed venous values (mean difference 3.3, 95% CI: 2.5, 4.0) and there was poor agreement overall (limits of agreement -1.10, 7.59). Veno-arterial carbon dioxide gradient moderately correlates with Fick CI and may be useful to identify patients with low CI. Central and mixed venous CO2 values should not be used interchangeably in PH.

Improving echographic monitoring of hemodynamics in critically ill patients: Validation of right cardiac output measurements through the modified subcostal window

ObjectiveWe aimed to assess the usefulness of using the right ventricle outflow tract (RVOT) velocity-time integral (VTI) for echocardiographic monitoring of cardiac output compared to the gold standard, the VTI along the left ventricle outflow tract (LVOT). DesignProspective observational study. SettingA tertiary intensive care unit. Patients100 consecutive patients. Interventions: echocardiographic monitoring in critically ill patients. Main variables of interestWe used intraclass correlation coefficients (ICC) to compare echocardiographic measurements of LVOT VTI through apical window with RVOT VTI through the parasternal and modified subcostal windows and to assess interobserver reproducibility. Preplanned post hoc analyses compared the ICC between ventilated and nonventilated patients. ResultsAt the time of echocardiography, 44 (44%) patients were mechanically ventilated and 28 (28%) were receiving vasoactive drugs. Good-quality measurements were obtained through the parasternal short-axis and/or apical views in 81 (81%) patients and in 100 (100%) patients through the subcostal window. Consistency with LVOT VTI was moderate for RVOT VTI measured from the modified subcostal view (ICC 0.727; 95%CI: 0.62–0.808) and for RVOT VTI measured from the transthoracic view (0.715; 95%CI: 0.59–0.807). ConclusionsMeasurements of RVOT VTI are moderately consistent with measurements of LVOT VTI. Adding the modified subcostal window allows monitoring RVOT VTI in all the patients of this selected cohort, even those under mechanical ventilation.

Measurement of Cardiac Output by Point-of-Care Transthoracic Echocardiography.

Traditionally measured with invasive methods or specialized equipment, stroke volume and cardiac output can be determined reliably with transthoracic echocardiography. This video guides the viewer in a step-by-step fashion through the technical aspects of Doppler echocardiographic assessment of cardiac output.

Validation of cardiac output estimation using the fourth-generation FloTrac/EV1000™ system in patients undergoing robotic-assisted off-pump coronary artery bypass surgery.

The pulmonary artery catheter (PAC)-despite its invasiveness-remains the gold standard for cardiac output (CO) monitoring. The FloTrac system, a less invasive hemodynamic monitor has been developed, which estimates CO using arterial pressure waveform analysis without external calibration. Recently, an upgraded version of FloTrac system with improved algorithm to follow changes in vascular resistance was introduced into the market. The aim of this study was to assess the reliability of the CO estimated from the fourth-generation FloTrac/EV1000 system (COFT) compared to that measured with PAC using the thermodilution method (COPAC) during robotic-assisted off-pump coronary artery bypass (OPCAB) surgery. COFT and COPAC were obtained simultaneously at 4 predefined time points during robotic-assisted OPCAB: 5min after the induction of general anesthesia (T1), after starting one-lung ventilation (T2), after capnothorax (T3), and after mini-thoracotomy was performed (T4). The agreement of data was investigated by Bland-Altman analysis. Thirty-four patients were initially enrolled. After exclusion, 32 patients and a total of 128 paired CO measurements were obtained. The overall bias was 1.46L/min, the 95% limits of agreements were - 3.40 to 6.33L/min, and the percentage error was 72.98%. Regression analysis of the systemic vascular resistance index (SVRI) and the bias between COPAC and COFT showed that the bias was moderately correlated with the SVRI (r2 = 0.43; p < 0.0001). Despite a software upgrade, the reliability of the fourth-generation FloTrac/EV1000™ system during robotic-assisted OPCAB to estimate CO was not acceptable, especially in patients with low SVRI.

Evaluation of a New Echocardiographic Tool for Cardiac Output Monitoring: An Experimental Study on A Controlled Hemorrhagic Shock Model in Anesthetized Piglets.

Background: Cardiac output (CO) monitoring is recommended in patients with shock. The search for a reliable, rapid, and noninvasive tool is necessary for clinical practice. A new echocardiographic CO flow index (COF) is the automatic calculation of the sub-aortic VTI multiplied by the automatic calculation of the heart rate (HR). The primary objective of this study was to show the correlation between COF and CO measured by thermodilution (COth) in a controlled hemorrhagic shock model in anesthetized piglets. Secondary objectives were to show the correlation between COth and CO calculated from left outflow tract (LVOT) measurement and manual VTI (COman), and CO measured by LVOT measurement and VTIauto (COauto). Methods: Prospective interventional experimental study. In seventeen ventilated and anesthetized piglets, a state of hemorrhagic shock was induced, maintained, then resuscitated and stabilized. The gold standard for CO and stroke volume measurement was thermodilution (COth). Results: 191 measurements were performed. The correlation coefficients (r) between COth and COF, COman, and COauto were 0.73 [0.62; 0.81], 0.66 [0.56; 0.74], and 0.73 [0.63; 0.81], respectively. Conclusions: In this study, the COF appears to have a strong correlation to the COth. This automatic index, which takes into account the HR and does not require the measurement of LVOT, could be a rapidly obtained index in clinical practice.

Wearable Seismocardiography-Based Assessment of Stroke Volume in Congenital Heart Disease.

Background Patients with congenital heart disease (CHD) are at risk for the development of low cardiac output and other physiologic derangements, which could be detected early through continuous stroke volume (SV) measurement. Unfortunately, existing SV measurement methods are limited in the clinic because of their invasiveness (eg, thermodilution), location (eg, cardiac magnetic resonance imaging), or unreliability (eg, bioimpedance). Multimodal wearable sensing, leveraging the seismocardiogram, a sternal vibration signal associated with cardiomechanical activity, offers a means to monitoring SV conveniently, affordably, and continuously. However, it has not been evaluated in a population with significant anatomical and physiological differences (ie, children with CHD) or compared against a true gold standard (ie, cardiac magnetic resonance). Here, we present the feasibility of wearable estimation of SV in a diverse CHD population (N=45 patients). Methods and Results We used our chest-worn wearable biosensor to measure baseline ECG and seismocardiogram signals from patients with CHD before and after their routine cardiovascular magnetic resonance imaging, and derived features from the measured signals, predominantly systolic time intervals, to estimate SV using ridge regression. Wearable signal features achieved acceptable SV estimation (28% error with respect to cardiovascular magnetic resonance imaging) in a held-out test set, per cardiac output measurement guidelines, with a root-mean-square error of 11.48 mL and R2 of 0.76. Additionally, we observed that using a combination of electrical and cardiomechanical features surpassed the performance of either modality alone. Conclusions A convenient wearable biosensor that estimates SV enables remote monitoring of cardiac function and may potentially help identify decompensation in patients with CHD.

Cardiac output monitoring with pulmonary versus trans-cardiopulmonary thermodilution in left ventricular assist devices: Interchangeable methods?

Cardiac output (CO) measurement is mandatory in patients with left ventricular assist devices (LVADs). Thermodilution with pulmonary artery catheter (PAC) remains the clinical gold standard to measure CO in these patients, however it is associated with several complications. Therefore, the agreement between PAC and new, minimally invasive monitoring methods in LVAD needs to be further investigated. The aim of this study was to assess the accuracy and reliability of transpulmonary thermodilution with a PiCCO2 monitor compared with pulmonary artery thermodilution with PAC in a LVAD. Continuous-flow LVADs were implanted in six mini-pigs to assist the left ventricle. We studied two methods of measuring CO—intermittent transpulmonary thermodilution (COTPTD) by PiCCO2 and intermittent pulmonary artery thermodilution by CAP, standard technique (COPTD)—obtained in four consecutive moments of the study: before starting the LVAD (basal moment), and with the LVAD started in normovolemia, hypervolemia (fluid overloading) and hypovolemia (shock hemorrhage). A total of 72 paired measurements were analysed. At the basal moment, COTPTD and COPTD were closely correlated (r 2 = 0.89), with a mean bias of −0.085 ± 0.245 L/min and percentage error of 16%. After 15 min of partial support LVAD, COTPTD and COPTD were closely correlated (r 2 = 0.79), with a mean bias of −0.040 ± 0.417 L/min and percentage error of 26%. After inducing hypervolemia, COTPTD and COPTD were closely correlated (r 2 = 0.78), with a mean bias of −0.093 ± 0.339 L/min and percentage error of 13%. After inducing hypovolemia, COTPTD and COPTD were closely correlated (r 2 = 0.76), with a mean bias of −0.045 ± 0.281 L/min and percentage error of 28%. This study demonstrates a good agreement between transpulmonary thermodilution by PiCCO monitor and pulmonary thermodilution by PAC in the intermittent measurement of CO in a porcine model with a continuous-flow LVAD.

Non-invasive continuous cardiac output monitoring in infants with hypoxic ischaemic encephalopathy

ObjectiveTo describe early, continuous, non-invasive measures of cardiac output (CO) and evolution over time in infants with hypoxic-ischaemic encephalopathy (HIE).Study designProspective observational study of 44 infants with HIE (23 mild, 17 moderate, 4 severe) and 17 term controls. Infants with HIE had non-invasive CO monitoring (NICOM) continuously in the neonatal unit. Term controls had NICOM recorded at 6 and 24 h. A mixed-modelling approach was used to assess change in CO over time by group.ResultsInfants with moderate HIE have significantly lower CO than the mild group at all timepoints (10.7 mls/kg/min lower, 95% CI:1.0,20.4, p = 0.03) which increases over time, driven by a gradual increase in stroke volume (SV). CO increased further during rewarming predominantly due to an increase in HR.ConclusionTH has a significant impact on HR but SV appears largely unaffected. NICOM may provide a non-invasive, continuous, low-cost alternative to monitoring CO in infants with HIE however further research is warranted.

Non-invasive cardiac output monitoring with electrical velocimetry after cardiac surgery in infants.

Low cardiac output following cardiac surgery is a major determinant of outcome that may be improved by early detection, yet there are no widely accepted methods for its measurement in young children. We evaluated the feasibility of the routine use of electrical velocimetry, a non-invasive technique providing continuous measurement of cardiac output, in infants in the early postoperative period. With ethical approval and parental consent, infants undergoing cardiac surgery were recruited. The ICON electrical velocimetry monitor was attached on admission to the intensive care unit (ICU) and remained for up to 24h. A total of 15 infants were recruited, median age 3months (interquartile range (IQR) 0.5-7.5) and weight 4.8kg (IQR 3.9-7.1), undergoing various operations. Cardiac index had a weak correlation with arterial lactate (r=-0.24, p=0.02) and no correlation with blood pressure, central venous pressure or arteriovenous oxygen difference. Data were recorded for a median of 19h (range 5-24), with lead detachment or movement artefact the most common causes of data loss. There was marked minute-to-minute variability, with 25% of consecutive measurements having >5% variability. Cardiac index measured by electrical velocimetry in infants in the early postoperative period is impaired by frequent data loss and marked intrapatient variability. Our feasibility study suggests that it is unsuitable for use as a routine monitoring tool in the setting of postsurgical ICU care.

Minute Stroke Distance Is a More Reproducible Measurement Than Cardiac Output in the Assessment of Fetal Ventricular Systolic Function

Echocardiographic quantification of fetal cardiac output (CO) aids clinical decision-making in the management of various cardiac and extracardiac diseases. Small variability in measuring semilunar valve dimension significantly reduces the reproducibility of the calculated CO. The authors propose minute stroke distance or velocity-time integral (VTI) as a more reproducible measure reflecting fetal ventricular systolic function. The aim of this study was to test the hypothesis that right and left ventricular minute VTI increase predictably with estimated fetal weight and are more reproducible than CO. Five hundred seventy-one singleton fetuses without cardiovascular pathology between 16 and 36weeks' gestation were reviewed retrospectively. Twenty-two fetuses with pathology resulting in low- or high-CO states were also assessed for comparison. VTI was measured in both ventricular outflow tracts at the level of the semilunar valve, excluding a Doppler insonation angle of >30°. Heart rate, semilunar valve dimension, and VTI determined minute VTI and CO. Inter- and intrarater variability were evaluated in a random 10% subset. Minute VTI and CO measurements were feasible in 67% to 89% of fetuses in this retrospective study. Minute VTI and CO increased with estimated fetal weight nonlinearly (R=0.61-0.94). The mean inter- and intrarater variability for VTI, 6% and 5.7%, were significantly less than for CO, 25% and 23.7% (P<.001 for all). Minute VTI is an easily measured, highly reproducible method of quantifying fetal ventricular systolic function. Variability in calculated CO from valve measurement differences is minimized by solely using VTI. Nomograms of minute VTI provide an efficient and precise assessment of fetal systolic function and may be used to track fetuses in disease states with low or high CO.

How can assessing hemodynamics help to assess volume status?

In critically ill patients, fluid infusion is aimed at increasing cardiac output and tissue perfusion. However, it may contribute to fluid overload which may be harmful. Thus, volume status, risks and potential efficacy of fluid administration and/or removal should be carefully evaluated, and monitoring techniques help for this purpose. Central venous pressure is a marker of right ventricular preload. Very low values indicate hypovolemia, while extremely high values suggest fluid harmfulness. The pulmonary artery catheter enables a comprehensive assessment of the hemodynamic profile and is particularly useful for indicating the risk of pulmonary oedema through the pulmonary artery occlusion pressure. Besides cardiac output and preload, transpulmonary thermodilution measures extravascular lung water, which reflects the extent of lung flooding and assesses the risk of fluid infusion. Echocardiography estimates the volume status through intravascular volumes and pressures. Finally, lung ultrasound estimates lung edema. Guided by these variables, the decision to infuse fluid should first consider specific triggers, such as signs of tissue hypoperfusion. Second, benefits and risks of fluid infusion should be weighted. Thereafter, fluid responsiveness should be assessed. Monitoring techniques help for this purpose, especially by providing real time and precise measurements of cardiac output. When decided, fluid resuscitation should be performed through fluid challenges, the effects of which should be assessed through critical endpoints including cardiac output. This comprehensive evaluation of the risk, benefits and efficacy of fluid infusion helps to individualize fluid management, which should be preferred over a fixed restrictive or liberal strategy.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00134-022-06808-9.

Accuracy and trending ability of finger plethysmographic cardiac output monitoring in late pregnancy.

Individuals in late pregnancy are at risk of significant hemodynamic variations, especially during Cesarean delivery. Although non-invasive monitoring might enable the early detection of variations in cardiac output (CO), clinical validation is lacking. In a prospective, single-centerstudy, we measured CO simultaneously with finger plethysmography and transthoracic echocardiography in 100 third-trimester pregnant individuals in the supine and left lateral decubitus (LLD) positions. A Bland-Altman analysis revealed a mean (standard deviation) bias of 1.36 (1.04) L·min-1 in the supine position (95% limits of agreement, -0.68 to 3.4 L·min-1; percent error, 26.6%), indicating overestimation by finger plethysmography. The intra-class correlation coefficient was 0.43 (95% confidence interval [CI], 0.33 to 0.51). Regarding the changes in CO induced by the supine-to-LLD transition, the concordance rate in a four-quadrant plot was 98.3% (95% CI, 91.1 to 99.9%). Our study showed a poor reliability of finger plethysmography for static measurement of CO. Nevertheless, finger plethysmography had a reasonably high concordance rate for the detection of CO changes secondary to positional changes in late-pregnant individuals. STUDY REGISTRATION DATE: www. gov (NCT03735043); registered 8 November 2018.

Is There a Correlation Between Left Ventricular Outflow Tract Velocity Time Integral and Stroke Volume Index in Patients Undergoing Cardiac Surgery?

IntroductionLeft ventricular outflow tract velocity time integral (LVOT VTI) is a promising surrogate for stroke volume (SV). However, there is controversy in the literature regarding its correlation with thermodilution or newer cardiac output measurement techniques. This study was conducted to determine the correlation between LVOT VTI determined by transesophageal echocardiography (TEE) with stroke volume index (SVI) calculated by thermodilution.MethodsConsecutive patients older than 17 years undergoing elective cardiac surgery with pulmonary artery catheter (PAC) and TEE monitoring between September 2021 and February 2022 were included in this prospective, descriptive, single-center study. LVOT VTI was measured using TEE after induction of anesthesia but before skin incision and at least four hours after initial LVOT VTI measurement. SVI was simultaneously measured using the continuous thermodilution technique with a PAC. The correlation between LVOT VTI and SVI was determined with Pearson’s correlation index.ResultsTwelve patients were included and 21 paired measurements were compared. Mean SVI was 31.62 ± 10.71 mL/m2 and mean LVOT VTI was 14.74 ± 4.79 cm. The Pearson's correlation index for the two measurements was r = 0.257, p = 0.262.ConclusionThis prospective study demonstrated a weak correlation between LVOT VTI and SVI in patients undergoing cardiac surgery.

Effects of two alveolar recruitment manoeuvres (sustained inflation and stepwise) followed by positive end-expiratory pressure on cardiac output (measured with lithium dilution), invasive blood pressure and arterial oxygen tension in isoflurane-anaesthetised goats

Alveolar recruitment manoeuvres (ARM) performed during general anaesthesia improve oxygenation; however cardiovascular depression may be observed. The aim of the study was to compare the effects of sustained inflation (SI) and stepwise ARMs on cardiac output (CO), mean arterial blood pressure and arterial oxygen tension (PaO2) in ten mechanically ventilated goats anaesthetised with isoflurane.In the SI ARM, peak inspiratory presure (PIP) was increased to 30 cmH2O and sustained for 20 s. In the stepwise ARM, the PIP was increased by 5 cmH2O each minute for three minutes from 10 to 25 cmH2O. Both ARMs were followed by positive end-expiratory pressure of 5 cmH2O. Paired lithium dilution CO measurements and arterial blood samples were obtained before and after each ARM. The order of the ARM was randomised and each goat was subjected to both techniques. Data was reported as median and interquartile range (IQR). Significance was set at 0.05.The median change in CO (measured by subtracting values after and before ARM) was −0.15 L min−1 (IQR -0.51; 0.03) and − 0.90 L min−1 (IQR -1.69; −0.58) for SI and stepwise ARM respectively (p = 0.04). The median change in PaO2 was 3 kPa (IQR -2.7; 7.6) and 0.4 kPa (IQR -3.4; 5.5) for SI and stepwise ARM respectively (p = 0.03).In conclusion, SI ARM causes less impact on CO and provides a better improvement in PaO2 compared to stepwise ARM in goats.

The Potential of Arterial Pulse Wave Analysis in Burn Resuscitation: A Pilot In Vivo Study.

While urinary output (UOP) remains the primary endpoint for titration of intravenous fluid resuscitation, it is an insufficient indicator of fluid responsiveness. Although advanced hemodynamic monitoring (including arterial pulse wave analysis [PWA]) is of recent interest, the validity of PWA-derived indices in burn resuscitation extremes has not been established. The goal of this paper is to test the hypothesis that PWA-derived cardiac output (CO) and stroke volume (SV) indices as well as pulse pressure variation (PPV) and systolic pressure variation (SPV) can play a complementary role to UOP in burn resuscitation. Swine were instrumented with a Swan-Ganz catheter for reference CO and underwent a 40% TBSA burns with varying resuscitation paradigms, and were monitored for 24 hours in an ICU setting under mechanical ventilation. The longitudinal changes in PWA-derived indices were investigated, and resuscitation adequacy was compared as determined by UOP vs PWA indices. The results indicated that PWA-derived indices exhibited trends consistent with reference CO and SV measurements: CO and SV indices were proportional to reference CO and SV, respectively (CO: postcalibration limits of agreement [LoA] = ±24.7 [ml/min/kg], SV: postcalibration LoA = ±0.30 [ml/kg]) while PPV and SPV were inversely proportional to reference SV (PPV: postcalibration LoA = ±0.32 [ml/kg], SPV: postcalibration LoA = ±0.31 [ml/kg]). The results also indicated that PWA-derived indices exhibited notable discrepancies from UOP in determining adequate burn resuscitation. Hence, it was concluded that the PWA-derived indices may have complementary value to UOP in assessing and guiding burn resuscitation.

A new noninvasive finger sensor (NICCI system) for cardiac output monitoring: A method comparison study in patients after cardiac surgery.

The new noninvasive finger sensor system NICCI (Getinge; Gothenburg, Sweden) allows continuous cardiac output monitoring. We aimed to investigate its cardiac output measurement performance. To investigate the NICCI system's cardiac output measurement performance. Prospective method comparison study. University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Fifty-one patients after cardiac surgery. We performed a method comparison study in 51 patients after cardiac surgery to compare NICCI cardiac output (CO NICCI ) and NICCI cardiac output calibrated to pulmonary artery thermodilution cardiac output measurement (CO NICCI-CAL ) with pulmonary artery thermodilution cardiac output (CO PAT ). As a secondary analysis we also compared CNAP cardiac output (CO CNAP ) and externally calibrated CNAP cardiac output (CO CNAP-CAL ) with CO PAT . We analysed 299 cardiac output measurement pairs. The mean of the differences (95% limits of agreement) between CO NICCI and CO PAT was 0.6 (-1.8 to 3.1) l min -1 with a percentage error of 48%. The mean of the differences between CO NICCI-CAL and CO PAT was -0.4 (-1.9 to 1.1) l min -1 with a percentage error of 29%. The mean of the differences between CO CNAP and CO PAT was 1.0 (-1.8 to 3.8) l min -1 with a percentage error of 53%. The mean of the differences between CO CNAP-CAL and CO PAT was -0.2 (-2.0 to 1.6) l min -1 with a percentage error of 35%. The agreement between CO NICCI and CO PAT is not clinically acceptable. The study was registered in the German Clinical Trial Register (DRKS00023189) after inclusion of the first patient on October 2, 2020.

Comparing cardiac output measurements using electrical cardiometry versus phase contrast cardiac magnetic resonance imaging

BackgroundThere is a growing interest in using non-invasive electrical cardiometry (EC) for continuous cardiac output (CO) measurements in neonates and children. There is a lack of sufficient data to validate CO measured by EC with currently accepted noninvasive techniques such as cardiac MRI (CMRI) in children. ObjectivesTo assess the degree of agreement between CO measured by EC and CMRI in children. We hypothesized that there is a good degree of agreement between CO measured by EC and CMRI in children. MethodsA retrospective chart review was performed to include patients who had noninvasive CO measured using EC (ICON®) and CMRI at our children's hospital between Feb 2019 and May 2020. Anthropometric, clinical and CO data were collected and CMRI parameters such as flow measurements in the aorta and pulmonary artery were analyzed. Data was analyzed using a Bland-Altman plot to compare the agreement between the CO obtained by EC vs. CMRI in this cohort of patients. ResultsA total of 52 patients with cardiac disease who had data available from CMRI and ICON® were included. The median (IQR) age was 174 (99,201) months and male: female ratio was 1.2:1. A total of 34/52 (60 %) patients had congenital heart disease and 22 had history of surgical interventions prior to noninvasive CO measurements. The Bland-Altman analysis for CO values by both EC and CMRI produced a mean bias (SD) of 0.12 (2.73) l/min for ICON® and the 95 % limits of agreement were −5.229 to 5.473 l/min. The precision error was only 1.86 %. The Bland- Altman plot for reproducibility for CO values by EC produced a mean bias (SD) of 0.15 (0.41) l/min with limits of agreement of −0.66 to 0.97 l/min. The percentage error was 2.34 %. ConclusionsIn our cohort of cardiac patients, there was a good degree of agreement between noninvasive CO as measured by Electric Cardiometry and Cardiac MRI.

Comparison between thermodilution and Fick methods for resting and exercise-induced cardiac output measurement in patients with chronic dyspnea.

Studies comparing thermodilution (TD) and the direct Fick method (dFM) for cardiac output (CO) measurement are rare. We compared CO measurements between TD (2–5 cold water injections), the dFM, and indirect Fick method (iFM) at rest and during exercise, and assessed the effect of averaging different numbers of TD measurements during exercise. This retrospective study included 300 patients (52.3% women, mean age 66 ± 11 years) having pulmonary hypertension (76.0%) or unexplained dyspnea. Invasive hemodynamic and gas exchange parameters were measured at rest (supine; n = 300) and during unloaded cycling (semi‐supine; n = 275) and 25‐W exercise (semi‐supine; n = 240). All three methods showed significant differences in CO measurement (ΔCO) at rest (p ≤ 0.001; ΔCO > 1 L/min: 45.0% [iFM vs. dFM], 42.0% [iFM vs. TD], and 45.7% [TD vs. dFM]). ΔCO (TD vs. dFM) was significant during unloaded cycling (p < 0.001; ΔCO > 1 L/min: 56.6%) but not during 25‐W exercise (p = 0.137; ΔCO > 1 L/min: 52.8%). ΔCO (TD vs. dFM) during 25‐W exercise was significant when using one or two (p ≤ 0.01) but not three (p = 0.06) TD measurements. Mean ΔCO (TD [≥3 measurements] vs. dFM) was −0.43 ± 1.98 and −0.06 ± 2.29 L/min during unloaded and 25‐W exercise, respectively. Thus, TD and dFM CO measurements are comparable during 25‐W exercise (averaging ≥3 TD measurements), but not during unloaded cycling or at rest. Individual ΔCOs vary substantially and require critical interpretation to avoid CO misclassification.