Bioreactance assessment of cardiac output lacks reliability for the follow-up of patients with pulmonary hypertension.

Cardiac output (CO) is one of the primary prognostic factors evaluated during the follow-up of patients treated for pulmonary hypertension (PH). It is recommended that it be measured using the thermodilution technique during right heart catheterization. The difficulty to perform iterative invasive measurements on the same individual led us to consider a non-invasive option. The aims of the present study were to assess the agreement between CO values obtained using bioreactance (Starling™ SV) and thermodilution, and to evaluate the ability of the bioreactance monitor to detect patients whose CO decreased by more than 15% during follow-up and, accordingly, its usefulness for patient monitoring. A prospective cohort study evaluating the performance of the Starling™ SV monitor was conducted in patients with clinically stable PH. Sixty patients referred for hemodynamic assessment were included. CO was measured using both the thermodilution technique and bioreactance during two follow-up visits. A total of 60 PH patients were included. All datasets were available at the baseline visit (V0) and 50 of them were usable during the follow-up visit (V1). Median [IQR] CO was 4.20 l/min [3.60-4.70] when assessed by bioreactance, and 5.30 l/min [4.57-6.20] by thermodilution (p<0.001). The Spearman correlation coefficient was 0.51 [0.36-0.64], and the average deviation on Bland-Altman plot was -1.25 l/min (95% CI [-1.48-1.01], p<0.001). The ability of the monitor to detect a variation in CO of more than 15% between two follow-up measurements, when such variation existed using thermodilution, was insufficient for clinical practice (AUC = 0.54, 95% CI [0.33-0.75]).

Effect of lower body negative pressure on cardiac and cerebral function in postural orthostatic tachycardia syndrome: A pilot MRI assessment.

Postural orthostatic tachycardia syndrome (POTS) is characterized by an excessive heart rate (HR) response upon standing and symptoms indicative of inadequate cerebral perfusion. We tested the hypothesis that during lower body negative pressure (LBNP), individuals with POTS would have larger decreases in cardiac and cerebrovascular function measured using magnetic resonance (MR) imaging. Eleven patients with POTS and 10 healthy controls were studied at rest and during 20 min of -25 mmHg LBNP. Biventricular volumes, stroke volume (SV), cardiac output (Qc), and HR were determined by cardiac MR. Cerebral oxygen uptake (VO2 ) in the superior sagittal sinus was calculated from cerebral blood flow (CBF; MR phase contrast), venous O2 saturation (SvO2 ; susceptometry-based oximetry), and arterial O2 saturation (pulse oximeter). Regional cerebral perfusion was determined using arterial spin labelling. HR increased in response to LBNP (p < 0.001) with no group differences (HC: +9 ± 8 bpm; POTS: +13 ± 11 bpm; p = 0.35). Biventricular volumes, SV, and Qc decreased during LBNP (p < 0.001). CBF and SvO2 decreased with LBNP (p = 0.01 and 0.03, respectively) but not cerebral VO2 (effect of LBNP: p = 0.28; HC: -0.2 ± 3.7 mL/min; POTS: +1.1 ± 2.0 mL/min; p = 0.33 between groups). Regional cerebral perfusion decreased during LBNP (p < 0.001) but was not different between groups. These data suggest patients with POTS have preserved cardiac and cerebrovascular function.

Integral assessment of gas exchange during veno-arterial ECMO: accuracy and precision of a modified Fick principle in a porcine model.

Assessment of native cardiac output during extracorporeal circulation is challenging. We assessed a modified Fick principle under conditions such as dead space and shunt in 13 anesthetized swine undergoing centrally cannulated veno-arterial extracorporeal membrane oxygenation (V-A ECMO, 308 measurement periods) therapy. We assumed that the ratio of carbon dioxide elimination (V̇co2) or oxygen uptake (V̇o2) between the membrane and native lung corresponds to the ratio of respective blood flows. Unequal ventilation/perfusion (V̇/Q̇) ratios were corrected towards unity. Pulmonary blood flow was calculated and compared to an ultrasonic flow probe on the pulmonary artery with a bias of 99 mL/min (limits of agreement -542 to 741 mL/min) with blood content V̇o2 and no-shunt, no-dead space conditions, which showed good trending ability (least significant change from 82 to 129 mL). Shunt conditions led to underestimation of native pulmonary blood flow (bias -395, limits of agreement -1,290 to 500 mL/min). Bias and trending further depended on the gas (O2, CO2) and measurement approach (blood content vs. gas phase). Measurements in the gas phase increased the bias (253 [LoA -1,357 to 1,863 mL/min] for expired V̇o2 bias 482 [LoA -760 to 1,724 mL/min] for expired V̇co2) and could be improved by correction of V̇/Q̇ inequalities. Our results show that common assumptions of the Fick principle in two competing circulations give results with adequate accuracy and may offer a clinically applicable tool. Precision depends on specific conditions. This highlights the complexity of gas exchange in membrane lungs and may further deepen the understanding of V-A ECMO.

Assessment of Fluid Responsiveness by Changes in End Tidal Carbon Dioxide During Passive Leg Raising Test and Fluid Challenge.

PURPOSE: It is rationale to predict fluid responsiveness for optimum hemodynamic management. Passive Leg Raising (PLR) causes reversible increase in cardiac output (CO) and changes in end-tidal CO2& pressure (ETCO2 ) can be considered surrogate for CO variations. We aimed to assess the variations in EtCO2 with PLR and fluid challenge (FC) and also compared it with systolic arterial pressure (SAP), mean arterial pressure (MAP), heart rate (HR) and central venous pressure (CVP). METHODOLOGY: This Prospective study was conducted in the ICU of a tertiary care teaching public hospital. PLR was performed before FC in patients of circulatory failure on mechanical ventilation. ETCO2 and hemodynamics were monitored and compared and correlated after PLR and FC. ROC curve of parameters, based on their Area under the Curve (AUC) was compared. MS Excel, PSPP version 1.0.1 was used for analysis. RESULTS: Among hundred patients studied, 74 showed ETCO2 change≥ 2 mmHg (>5%) and were fluid responders. Increase in Etco2 after PLR at 1minute and FC at 30 minutes was statistically significant (p=2.73×10-73) so is SAP(p=4.02×10-75) and MAP(p=1.75×10-75). AUC of predictive performance of parameters showed change in ETCO2 (AUC ROC 0.985 [0.938 to 0.999]) had significantly outperformed CVP (AUCROC 0.822 [0.733-0.892]), SAP (AUCROC 0.793 [0.701-0.868]), MAP (AUCROC 0.810 [0.719-0.881]), HR (AUCROC 0.574 [0.471-0.673]).

Conclusion: Variations in ETCO2 >5% induced by PLR can predict fluid responsiveness and is a reliable, non-invasive, easy, quick, and reversible method. ETCO2 is better predictor than SAP, MAP, CVP, and HR during PLR and FC. We may recommend PLR-induced changes in ETCO2 to predict fluid responsiveness in mechanically ventilated patients.

Ratio of Mixed Venous Oxygen Saturation-to-Pulmonary Capillary Wedge Pressure: Insights From the Veterans Affairs Clinical Assessment, Reporting, and Tracking Program.

BACKGROUND: Hemodynamic values from right heart catheterization aid diagnosis and clinical decision-making but may not predict outcomes. Mixed venous oxygen saturation percentage and pulmonary capillary wedge pressure relate to cardiac output and congestion, respectively. We theorized that a novel, simple ratio of these measurements could estimate cardiovascular prognosis. METHODS: We queried Veterans Affairs' databases for clinical, hemodynamic, and outcome data. Using the index right heart catheterization between 2010 and 2016, we calculated the ratio of mixed venous oxygen saturation-to-pulmonary capillary wedge pressure, termed ratio of saturation-to-wedge (RSW). The primary outcome was time to all-cause mortality; secondary outcome was 1-year urgent heart failure presentation. Patients were stratified into quartiles of RSW, Fick cardiac index (CI), thermodilution CI, and pulmonary capillary wedge pressure alone. Kaplan-Meier curves and Cox proportional hazards models related comparators with outcomes. RESULTS: Of 12 019 patients meeting inclusion criteria, 9826 had values to calculate RSW (median 4.00, interquartile range, 2.67-6.05). Kaplan-Meier curves showed early, sustained separation by RSW strata. Cox modeling estimated that increasing RSW by 50% decreases mortality hazard by 19% (estimated hazard ratio, 0.81 [95% CI, 0.79-0.83], P<0.001) and secondary outcome hazard by 28% (hazard ratio, 0.72 [95% CI, 0.70-0.74], P<0.001). Among the 3793 patients with data for all comparators, Cox models showed RSW best associated with outcomes (by both C statistics and Bayes factors). Furthermore, pulmonary capillary wedge pressure was superior to thermodilution CI and Fick CI. Multivariable adjustment attenuated without eliminating the association of RSW with outcomes. CONCLUSIONS: In a large national database, RSW was superior to conventional right heart catheterization indices at assessing risk of mortality and urgent heart failure presentation. This simple calculation with routine data may contribute to clinical decision-making in this population.

COMBED: Rapid non-invasive Cardiac Output Monitoring Baseline assessment in adult Emergency Department patients with haemodynamic instability.

OBJECTIVE: The application of rapid, non-operator-dependent, non-invasive cardiac output monitoring (COM) may provide early physiological information in ED patients with haemodynamic instability (HI). Our primary objective was to assess the feasibility of measuring pre-intervention (baseline) cardiac index (CI) and associated haemodynamic parameters. METHODS: We performed a prospective observational study of adults shortly after presentation to the ED of a large university hospital with tachycardia or hypotension or both. We applied non-invasive COM for 5 min and recorded CI, mean arterial pressure (MAP), stroke volume index (SVI) and systemic vascular resistance index (SVRI). We assessed for differences between those presenting with hypotension or hypotension and tachycardia with tachycardia alone and between those with or without suspected infection. RESULTS: We obtained haemodynamic parameters in 46 of 49 patients. In patients with hypotension or hypotension and tachycardia (n = 15) rather than tachycardia alone (n = 31), we observed a lower MAP (60.8 vs 87.7, P < 0.0001), CI (2.8 vs 3.9, P = 0.0167) and heart rate (85.5 vs 115.4, P < 0.0001). There was no difference in SVI (33.7 vs 33.4, P = 0.93) or SVRI (1970 vs 2088, P = 0.67). Patients with suspected infection had similar haemodynamic values except for a lower SVRI (1706 vs 2237, P = 0.011). CONCLUSIONS: Rapid, non-operator-dependent, non-invasive COM was possible in >90% of ED patients presenting with HI. Compared with tachycardia alone, patients with hypotension had lower CI, MAP and heart rate, while those with suspected infection had a lower SVRI. This technology provides novel insights into the early state of the circulation in ED patients with HI.

Assessment of extravascular lung water by measuring the number of pulmonary ultrasound B-lines before and after CBP in patients with MODS.

ABSTRACT: To determine whether the change in the number of pulmonary ultrasound B-line can accurately assess the extravascular lung water (EVLW) before and after continuous bedside blood purification (CBP) in patients with multiple organ dysfunction syndrome (MODS).Seventy-six patients with MODS who underwent CBP were examined within 24 hours before and after CBP using pulmonary ultrasound to detect the number of ultrasound B-line or using pulse indicator continuous cardiac output method to examine extravascular lung water, blood oxygenation index, and B-type natriuretic peptide (BNP) content. The correlation of the change in the number of B lines before and after CBP treatment with the negative balance of 24 hours liquid, the change of oxygenation index, and BNP content were analyzed.In the 76 patients, CBP treatment significantly decreased EVLW, the number of B-line, and BNP (P < .05 for all), while it significantly increased the oxygenation index (P < .05). Correlation analysis showed that the decrease in B-line number after CBP treatment was positively correlated with the 24 hours negative lung fluid balance, decrease of EVLW, oxygenation index improvement, and decreased BNP content. The change in the numbers of pulmonary ultrasound B-line can accurately assess the change of EVLW before and after CBP treatment and reflect the efficiency of ventilation in the lungs and the risk of heart failure.Thus, it can replace pulse indicator continuous cardiac output as an indicator for evaluating EVLW in patients with MODS treated with CBP.

Assessment of the right ventricle in donation after circulatory death hearts.

In donation after circulatory death heart transplantation, the donor heart is exposed to circulatory load. The right ventricle, due to its structure, has high compliance for volume load but is particularly vulnerable to increased pressure load. This study used a porcine model to conduct a functional assessment of the hemodynamics of the heart, with a focus on the right ventricle. Six pigs weighing 24.6 ± 1.4 kg were used. Circulatory death was induced by asphyxiation after median sternotomy. After 30 minutes in the state of global warm ischemia, the ascending aorta was clamped, followed by a 20-minute reperfusion of the heart with a 20°C blood cardioplegia solution. Systemic circulation was established by cardiopulmonary bypass after aortic cross-clamping. After initial reperfusion, the blood cardioplegia solution was replaced with blood. The blood was then rewarmed while the heart was still in a non-working state. Cardiac function was assessed twice in situ, first by the thermodilution method, and then, by the pressure-volume measurement both at preischemia and at three hours after initiation of reperfusion. The recovery rate of cardiac output was 75%. End-systolic elastance (P = .02) and pulmonary arterial elastance significantly increased (P = .03), but the ratio of arterial elastance to end-systolic elastance was preserved (P = .91) in the right ventricle. Despite a decrease in cardiac output after reperfusion from warm ischemia, the right ventricle had a potential to respond the elevated afterload. It is important that donations after circulatory death heart transplantation should be performed with attention to avoiding right ventricular distension.

Haemodynamic characteristics of COVID-19 patients with acute respiratory distress syndrome requiring mechanical ventilation. An invasive assessment using right heart catheterization.

AIMS: Interstitial pneumonia due to coronavirus disease 2019 (COVID-19) is often complicated by severe respiratory failure. In addition to reduced lung compliance and ventilation/perfusion mismatch, a blunted hypoxic pulmonary vasoconstriction has been hypothesized, that could explain part of the peculiar pathophysiology of the COVID-19 cardiorespiratory syndrome. However, no invasive haemodynamic characterization of COVID-19 patients has been reported so far. METHODS AND RESULTS: Twenty-one mechanically-ventilated COVID-19 patients underwent right heart catheterization. Their data were compared both with those obtained from non-mechanically ventilated paired control subjects matched for age, sex and body mass index, and with pooled data of 1937 patients with 'typical' acute respiratory distress syndrome (ARDS) from a systematic literature review. Cardiac index was higher in COVID-19 patients than in controls [3.8 (2.7-4.5) vs. 2.4 (2.1-2.8) L/min/m2 , P < 0.001], but slightly lower than in ARDS patients (P = 0.024). Intrapulmonary shunt and lung compliance were inversely related in COVID-19 patients (r = -0.57, P = 0.011) and did not differ from ARDS patients. Despite this, pulmonary vascular resistance of COVID-19 patients was normal, similar to that of control subjects [1.6 (1.1-2.5) vs. 1.6 (0.9-2.0) WU, P = 0.343], and lower than reported in ARDS patients (P < 0.01). Pulmonary hypertension was present in 76% of COVID-19 patients and in 19% of control subjects (P < 0.001), and it was always post-capillary. Pulmonary artery wedge pressure was higher in COVID-19 than in ARDS patients, and inversely related to lung compliance (r = -0.46, P = 0.038). CONCLUSIONS: The haemodynamic profile of COVID-19 patients needing mechanical ventilation is characterized by combined cardiopulmonary alterations. Low pulmonary vascular resistance, coherent with a blunted hypoxic vasoconstriction, is associated with high cardiac output and post-capillary pulmonary hypertension, that could eventually contribute to lung stiffness and promote a vicious circle between the lung and the heart.

Noninvasive Assessment of Cardiac Output: Accuracy and Precision of the Closed-Circuit Acetylene Rebreathing Technique for Cardiac Output Measurement.

Background Accurate assessment of cardiac output is critical to the diagnosis and management of various cardiac disease states; however, clinical standards of direct Fick and thermodilution are invasive. Noninvasive alternatives, such as closed-circuit acetylene (C2H2) rebreathing, warrant validation. Methods and Results We analyzed 10 clinical studies and all available cardiopulmonary stress tests performed in our laboratory that included a rebreathing method and direct Fick or thermodilution. Studies included healthy individuals and patients with clinical disease. Simultaneous cardiac output measurements were obtained under normovolemic, hypovolemic, and hypervolemic conditions, along with submaximal and maximal exercise. A total of 3198 measurements in 519 patients were analyzed (mean age, 59 years; 48% women). The C2H2 method was more precise than thermodilution in healthy individuals with half the typical error (TE; 0.34 L/min [r=0.92] and coefficient of variation, 7.2%) versus thermodilution (TE=0.67 [r=0.70] and coefficient of variation, 13.2%). In healthy individuals during supine rest and upright exercise, C2H2 correlated well with thermodilution (supine: r=0.84, TE=1.02; exercise: r=0.82, TE=2.36). In patients with clinical disease during supine rest, C2H2 correlated with thermodilution (r=0.85, TE=1.43). C2H2 was similar to thermodilution and nitrous oxide (N2O) rebreathing technique compared with Fick in healthy adults (C2H2 rest: r=0.85, TE=0.84; C2H2 exercise: r=0.87, TE=2.39; thermodilution rest: r=0.72, TE=1.11; thermodilution exercise: r=0.73, TE=2.87; N2O rest: r=0.82, TE=0.94; N2O exercise: r=0.84, TE=2.18). The accuracy of the C2H2 and N2O methods was excellent (r=0.99, TE=0.58). Conclusions The C2H2 rebreathing method is more precise than, and as accurate as, the thermodilution method in a variety of patients, with accuracy similar to an N2O rebreathing method approved by the US Food and Drug Administration.

Assessment of Hemodynamic Parameters in Recipients of a Liver Transplant.

INTRODUCTION: The control of all hemodynamic parameters among patients after liver transplantation is critical for better graft survival and to reduce the risk of perioperative complications. The value of cardiac output (CO) and stroke volume (SV) below normal promote the development of cardiovascular diseases. MATERIALS AND METHODS: The study was conducted on a group of 43 patients after liver transplantation: 16 women and 27 men 0.5 to 29 years after the surgery at the Department of Transplantation Medicine, Nephrology and Internal Diseases, Institute of Transplantology, Medical University of Warsaw, Infant Jesus Clinical Hospital in Warsaw, Poland. The hemodynamic parameters were measured due to 4 electrocardiogram electrodes with the Cardiac Monitor ICON Osypka Medical. RESULTS: Patients after liver transplantation (LTx) showed values of CO (average 5.27 L/min, standard deviation [SD] = 0.92) and stroke volume (average 67.08 mL, SD = 10.96) below normal. The average thoracic fluid content value among women is 21.81 (1/kΩ), SD = 3.28, and for men 24.04 (1/kΩ), SD = 4.75. Only 37% of patients had a body mass index with normal values, with 63% above expected values: 42% with overwise and 21% with a first stage of obesity. CONCLUSION: The hemodynamic parameters should be controlled among patients after LTx. CO and SV below normal are predictors of a higher risk of cardiovascular diseases.

Systematic assessment of fluid responsiveness during early septic shock resuscitation: secondary analysis of the ANDROMEDA-SHOCK trial.

BACKGROUND: Fluid boluses are administered to septic shock patients with the purpose of increasing cardiac output as a means to restore tissue perfusion. Unfortunately, fluid therapy has a narrow therapeutic index, and therefore, several approaches to increase safety have been proposed. Fluid responsiveness (FR) assessment might predict which patients will effectively increase cardiac output after a fluid bolus (FR+), thus preventing potentially harmful fluid administration in non-fluid responsive (FR-) patients. However, there are scarce data on the impact of assessing FR on major outcomes. The recent ANDROMEDA-SHOCK trial included systematic per-protocol assessment of FR. We performed a post hoc analysis of the study dataset with the aim of exploring the relationship between FR status at baseline, attainment of specific targets, and clinically relevant outcomes. METHODS: ANDROMEDA-SHOCK compared the effect of peripheral perfusion- vs. lactate-targeted resuscitation on 28-day mortality. FR was assessed before each fluid bolus and periodically thereafter. FR+ and FR- subgroups, independent of the original randomization, were compared for fluid administration, achievement of resuscitation targets, vasoactive agents use, and major outcomes such as organ dysfunction and support, length of stay, and 28-day mortality. RESULTS: FR could be determined in 348 patients at baseline. Two hundred and forty-two patients (70%) were categorized as fluid responders. Both groups achieved comparable successful resuscitation targets, although non-fluid responders received less resuscitation fluids (0 [0-500] vs. 1500 [1000-2500] mL; p 0.0001), exhibited less positive fluid balances, but received more vasopressor testing. No difference in clinically relevant outcomes between FR+ and FR- patients was found, including 24-h SOFA score (9 [5-12] vs. 8 [5-11], p = 0.4), need for MV (78% vs. 72%, p = 0.16), need for RRT (18% vs. 21%, p = 0.7), ICU-LOS (6 [3-11] vs. 6 [3-16] days, p = 0.2), and 28-day mortality (40% vs. 36%, p = 0.5). Only thirteen patients remained fluid responsive along the intervention period. CONCLUSIONS: Systematic assessment allowed determination of fluid responsiveness status in more than 80% of patients with early septic shock. Fluid boluses could be stopped in non-fluid responsive patients without any negative impact on clinical relevant outcomes. Our results suggest that fluid resuscitation might be safely guided by FR assessment in septic shock patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT03078712. Registered retrospectively on March 13, 2017.

Cardiac performance assessment during cardiopulmonary exercise test can improve the management of children with repaired congenital heart disease.

BACKGROUND: Children with repaired congenital heart disease (CHD) have impaired maximal aerobic capacity (VO2max). Determining the causes of their VO2max alteration remains challenging. Cardiac output measure using thoracic impedancemetry during cardiopulmonary exercise tests (CPET) can help to understand the determinants of VO2max in children with open-heart repaired CHD. METHOD: We analyzed CPET in 77 children with repaired CHD. Among them, 55 patients had residual lesions. Patients with repaired CHD were compared with 44 age-matched healthy individuals. Maximal oxygen content brought to capillaries (QO2max) and oxygen muscle diffusion capacity (DO2) were assessed using cardiac output measure, Fick principle and simplified Fick law. RESULTS: In the 55 patients with residual lesion, VO2max, QO2max and DO2 were lower than those of controls (76.1 vs 86% of theoretical value, p < 0.01; 2.15 vs 2.81 L/mn, p < 0.001; 24.7 vs 28.8 ml/min/mmHg, p < 0.05). Decrease in QO2max was due to both impaired stroke volume and chronotropic insufficiency (48 vs 53 ml/m2 and p < 0.05; 171 vs 185/min p < 0.001). Patients without residual lesion (22/77) had normal VO2max with lower maximal heart rate compensated by higher SV (p < 0.05). CONCLUSION: Aerobic capacity was normal in children without residual lesions after CHD repair. Patients with residual lesion have impaired VO2max due to both lower central and peripheral determinants. Measuring cardiac performance during CPET allowed a better selection of patients with altered cardiac reserve that can benefit from residual lesion treatment and find the good timing for intervention. Detection of peripheral deconditioning can lead to a rehabilitation program.

Accuracy of Impedance Cardiography for Hemodynamic Assessment During Rest and Exercise in Wheelchair Rugby Players.

Purpose: The aim of the study was to analyze the accuracy of impedance cardiography (ICG) for hemodynamic assessment in wheelchair rugby players during rest and exercise. Method: The study included 21 players (mean age 33.0 ± 5.4, 86% male) with posttraumatic tetraplegia. ECG, echocardiography, and gas exchange analysis during rest and exercise were used to obtain heart rate (HR), stroke volume (SV), and cardiac output (CO) for comparison with PhysioFlow®. Results: There was a good correlation between reference methods and ICG for HR, SV, CO at rest and CO at peak exercise (r = 0.69-0.77, p < .001) and a very good correlation for peak HR (r = 0.91, p < .0001). ICG overestimated SV at rest, CO at rest, and peak CO, which resulted in low intraclass correlation coefficients (ICC = 0.250 and 0.570). Conclusions: ICG can serve as a good estimate of basic hemodynamic parameters during rest and exercise in wheelchair rugby players but overestimates stroke volume and cardiac output.

Influence of left ventricular assist device pressure-flow characteristic on exercise physiology: Assessment with a verified numerical model.

Current left ventricular assist devices are designed to reestablish patient's hemodynamics at rest but they lack the suitability to sustain the heart adequately during physical exercise. Aim of this work is to assess the performance during exercise of a left ventricular assist device with flatter pump pressure-flow characteristic and increased pressure sensitivity (left ventricular assist device 1) and to compare it to the performance of a left ventricular assist device with a steeper characteristic (left ventricular assist device 2). The two left ventricular assist devices were tested at constant rotational speed with a verified computational cardiorespiratory simulator reproducing an average left ventricular assist device patient response to exercise (EXE↑) and a left ventricular assist device patient with no chronotropic and inotropic response (EXE→). According to the results, left ventricular assist device 1 pumps a higher flow than left ventricular assist device 2 both at EXE↑ (6.3 vs 5.6 L/min) and at EXE→ (6.7 vs 6.1 L/min), thus it better unloads the left ventricle. Left ventricular assist device 1 increases the power delivered to the circulation from 0.63 W at rest to 0.67 W at EXE↑ and 0.82 W at EXE→, while left ventricular assist device 2 power shows even a minimal decrease. Left ventricular assist device 1 better sustains exercise hemodynamics and can provide benefits in terms of exercise performance, especially for patients with a poor residual left ventricular function, for whom the heart can hardly accommodate an increase of cardiac output.

Assessment of volume status and volume responsiveness in the ICU: Protocol for an observational, multicentre cohort study.

BACKGROUND: Expansion of the intravascular compartment is common to treat haemodynamic instability in ICU patients. The most useful and accurate variables to guide and evaluate a fluid challenge remain debated and incompletely investigated resulting in significant variability in practice. The analogue mean systemic pressure has been reported as a measure of the intravascular volume state. METHODS: This is a protocol and statistical analysis plan for a review of the application of an analogue of the mean systemic pressure and the use of derived variables to assess the volume state and volume responsiveness. A pulmonary artery catheter was used in 286 postoperative cardiac surgical patients to monitor cardiac output before and after a fluid bolus in addition to arterial and central venous pressures. With otherwise similar monitoring, echocardiography was used in 540 general ICU patients to determine cardiac outputs and indices related to intravascular filling. The responses to a fluid bolus or the passive leg raising manoeuvre will be investigated using continuous and dichotomous definitions of volume responsiveness. The results will be stratified according to the method of monitoring cardiac output. CONCLUSIONS: This study investigating 2 cohorts that encompass a wide variety of reasons for haemodynamic instability will illustrate the applicability of the analogue mean systemic pressure and derived variables to assess the volume state and responsiveness. The results may guide the rationale and design of interventional studies.

Rapid response team review of hemodynamically unstable ward patients: The accuracy of cardiac index assessment.

PURPOSE: Intensive care doctors commonly attend rapid response team (RRT) reviews of hospital-ward patients with hemodynamic instability and estimate the patient's likely cardiac index (CI). We aimed to non-invasively measure the CI of such patients and assess the level of agreement between such measurements and clinically estimated CI categories (low <2L/min/m2, normal 2-2.99L/min/m2 or high ≥3L/min/m2). MATERIALS AND METHODS: A prospective, observational study of non-invasive measurement and clinical estimation of CI categories in 50 adult hospital-ward patients who activated the RRT for 'hemodynamic instability' (tachycardia > 100BPM or hypotension < 90mmHg or both). RESULTS: The CI was measured in 47/50(94%) patients and the mean CI was 3.5(95% CI 3.2-3.7) L/min/m2. Overall, 30(64%) patients had a high CI, 13(28%) and 4(9%) had a normal and a low CI, respectively. The level of agreement between measured and clinically estimated CI categories was low(19.2%). Sensitivity and positive predictive values of clinical estimation were low(0% and 3.3% for high CI, and 0% and 50% for low CI, respectively). CONCLUSIONS: Non-invasive CI measurement was possible in almost all hospital-ward patients triggering RRT review for hemodynamic instability. In such patients, the CI was high, and intensive care clinicians were unable to identify a low or a high CI state.

Cardiac output measurements during high-risk Cesarean section using electrical bioreactance or arterial waveform analysis: assessment of agreement.

OBJECTIVE: Maternal hemodynamics change significantly during Cesarean section complicated by massive hemorrhage or severe hypertensive disease. Cardiac output (CO) monitoring aids early, goal-directed hemodynamic therapy. The aim of this study was to record hemodynamic changes observed during Cesarean section in pregnancies at high risk of hemodynamic instability, using invasive (LiDCOrapid™) and non-invasive (NICOM®) devices, and to assess agreement between the two devices in measuring CO. METHODS: Simultaneous intraoperative hemodynamic measurements were taken using the LiDCOrapid and NICOM devices, following standardized techniques, in women at high risk of hemodynamic instability undergoing Cesarean section. Agreement in CO measurements between the two devices was assessed using Bland-Altman plots and the agreement:tolerability index (ATI). Agreement analyses were performed for repeated measures in subjects, using centiles. RESULTS: From 10 women, 307 paired measurements were analyzed. Mean bias (defined as the mean difference in CO measurements between the LiDCOrapid and NICOM devices) was 3.05 (95% CI, 1.89 to 4.21) L/min. Limits of agreement ranged from -1.58 (95% CI, -4.47 to -0.14) to 7.68 (95% CI, 6.24 to 10.56) L/min. The resulting agreement interval was 9.26 L/min which returned an ATI of 2.3. CONCLUSIONS: There are large mean differences between CO measurements obtained during Cesarean section using the LiDCOrapid and NICOM hemodynamic monitors in pregnant women at high risk of hemodynamic instability, indicating that they should not be considered interchangeable clinically. There is an unacceptably low level of agreement (ATI > 2) in CO measurements between the devices, conferring a high risk of clinical misclassification during massive hemorrhage. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Assessment of cardiac function in infants with transposition of the great arteries after surgery: comparison of two methods.

BACKGROUND: Assessment of cardiac function is crucial in pediatric patients undergoing cardiovascular surgery, monitoring cardiac output and changing hemodynamic conditions during surgery accordingly is important to improve post-surgical outcome. We aimed to measure cardiac index (CI) and maximal rate of the increase of left ventricular pressure dp/dt(max) with the pressure recording analytic method (PRAM, MostCare®) and compared it with transthoracic echocardiographic cardiac index estimation in infants with transposition of the great arteries (TGA) undergoing surgical correction. METHODS: We enrolled 74 infants with TGA consecutively into this study. CI and dp/dt(max) were measured with PRAM and echocardiography at 0, 4, 8, 12, 24 and 48 h postoperatively. Blood brain natriuretic peptide (BNP) and blood lactate (Lac) were measured at baseline and after operation. RESULTS: The median age at surgery was 13 days (range 1-25 days) with an average weight of 3.24 kg (range 2.31-4.17 kg). CI estimated by PRAM was 1.11 ± 0.12 L/min/m2 (range 0.69-1.36) and by Doppler echocardiography was 1.13 ± 0.13 L/min/m2 (range 0.76-1.40). dp/dt(max) estimated by PRAM was 1.31 ± 0.03 mmHg/s (range 1.23-1.43) and by Doppler echocardiography was 1.31 ± 0.04 L/min/m2 (range 1.25-1.47). CI (r = 0.817, P < 0.001) and dp/dt(max) (r = 0.794, P < 0.001) measured by two methods were highly correlated with a linear relation. Blood BNP and lactate increased to the highest level at 8-12 h post-operatively. CONCLUSIONS: In the early post-operative period, PRAM provides reliable estimates of cardiac index and dp/dt(max) value compared with echocardiographic measurements. PRAM through mostcare® is a reliable continuous monitoring method for peri-operative management in children with congenital heart disease.