Cardiac Output Values Research Articles

P79: Comparison of Cardiovascular Models for Validation of Controlled Ventricular Assist Devices

Purpose of the Study: In the evaluation of control schemes for Ventricular Assist Devices (VADs), it is important to utilize a precise model of the human cardiovascular system for both in silico and in vitro testing. As various patients and experimental data result in varying performance of cardiovascular models (CVM) and their respective parameters, it is necessary to assess the robustness of the control schemes through examination with a broad range of parameter sets. To achieve this, we conducted a comparison of two state-of-the-art CVMs and analyzed their interaction with a controlled VAD under dilated heart conditions. Methods: In this study, two state-of-the-art CVMs were investigated: the model developed by Colacino et al. (2007) (COLA) and the model by Lim et al. (2010) (LIM). Both CVMs were implemented as real-time capable models and evaluated both in silico and in vitro using our hybrid mock circulation test bench. Similar test cases were established for both models, encompassing a rest-to-exercise scenario and variations of preload and afterload conditions. These test cases were simulated and experimentally tested, with the results of the left ventricular (LV) pressure, mean aortic (MAP) pressure, cardiac output (CO), pressure-volume (PV) loops facilitating the analysis of the response of the dilated heart supported with a controlled VAD, and the comparison with the response of the healthy heart (HH). We tested six different physiological controllers and the influence of the models on the controller’s reaction. Results: During the rest-to-exercise experiment, the comparison of the two CVMs revealed comparable results in terms of MAP and CO. However, the pressure transition from systole to diastole in the COLA model was found to be faster than in the LIM model. Under the same conditions, the PV loops also exhibited a similar variation, showing differences in shape as well as volume shift. For the rest-to-exercise conditions, the COLA model achieved a higher LV volume compared to the LIM model due to the assumption of different unstressed venous volumes (approx. 20% less for the LIM model). For the rest conditions, the CO was comparable to that of the HH in both models. Conversely, during the exercise condition, the COLA model showed a deficit of approx. 2.2 L/min, while the LIM model was relatively close to the CO of the HH. The systolic pressure controller, as one of the physiological controllers tested, results in CO of about 8.7 L/min (COLA) and about 6.9 L/min (LIM) under exercise conditions, whereas the MAP is nearly the same at about 80 mmHg for both models. Conclusion: The distinct parameters and variations in the structure of the CVMs under investigation resulted in varying blood volumes in the compartments, leading to different pressures during the cardiac cycle and diverse CO values for the dilated heart. This implies differing operating conditions for evaluating the VAD controllers and highlights the need to broaden the test space.Figure 1. Comparison of the COLA (left) and LIM (right) CVM for the rest-to-exercise scenario of a dilated heart with an ejection fraction of around 23 %. The left ventricular pressure (plv), left ventricular volume (Vlv), mean aortic pressure (pMAP), cardiac output of the dilated heart (CO) and healthy heart (COref) are shown.

Impact of cardiac output and alveolar ventilation in estimating ventilation/perfusion mismatch in ARDS using electrical impedance tomography

IntroductionElectrical impedance tomography (EIT) can be used to assess ventilation/perfusion (V/Q) mismatch within the lungs. Several methods have been proposed, some of them neglecting the absolute value of alveolar ventilation (VA) and cardiac output (QC). Whether this omission results in acceptable bias is unknown.MethodsPixel-level V/Q maps of 25 ARDS patients were computed once considering (absolute V/Q map) and once neglecting (relative V/Q map) the value of QC and VA. Previously published indices of V/Q mismatch were computed using absolute V/Q maps and relative V/Q maps. Indices computed with relative V/Q maps were compared to their counterparts computed using absolute V/Q maps.ResultsAmong 21 patients with ratio of alveolar ventilation to cardiac output (VA/QC) > 1, relative shunt fraction was significantly higher than absolute shunt fraction [37% (24–66) vs 19% (11–46), respectively, p < 0.001], while relative dead space fraction was significantly lower than absolute dead space fraction [40% (22–49) vs 58% (46–84), respectively, p < 0.001]. Relative wasted ventilation was significantly lower than the absolute wasted ventilation [16% (11–27) vs 29% (19–35), respectively, p < 0.001], while relative wasted perfusion was significantly higher than absolute wasted perfusion [18% (11–23) vs 11% (7–19), respectively, p < 0.001]. The opposite findings were retrieved in the four patients with VA/QC < 1.ConclusionNeglecting cardiac output and alveolar ventilation when assessing V/Q mismatch indices using EIT in ARDS patients results in significant bias, whose direction depends on the VA/QC ratio value.

Agreement between Electrical Cardiometry and Pulmonary Artery Thermodilution for Measuring Cardiac Output in Isoflurane-Anesthetized Dogs.

In animals, invasive pulmonary artery thermodilution (PATD) is a gold standard for cardiac output (CO) monitoring, but it is impractical in clinical settings. This study evaluates the agreement between PATD and noninvasive electrical cardiometry (EC) for measuring CO and analyzes the other EC-derived hemodynamic variables in six healthy anesthetized dogs subjected to four different hemodynamic events in a sequential order: (1) euvolemia (baseline); (2) hemorrhage (33% blood volume loss); (3) autologous blood transfusion; and (4) 20 mL/kg colloid bolus. The CO measurements obtained using PATD and EC are compared using Bland-Altman analysis, Lin's concordance correlation (LCC), and polar plot analysis. Values of p < 0.05 are considered significant. The EC measurements consistently underpredict the CO values as compared with PATD, and the LCC is 0.65. The EC's performance is better during hemorrhage, thus indicating its capability in detecting absolute hypovolemia in clinical settings. Even though the percentage error exhibited by EC is 49.4%, which is higher than the standard (<30%), EC displays a good trending ability. Additionally, the EC-derived variables display a significant correlation with the CO measured using PATD. Noninvasive EC may have a potential in monitoring trends in hemodynamics in clinical settings.

Correlation between pulmonary vascular performance and hemodynamics in patients with pulmonary arterial hypertension

ABSTRACT Objective To explore the correlation between pulmonary vascular performance and hemodynamics in patients with pulmonary arterial hypertension (PAH), using right heart catheterization (RHC) and intravascular ultrasound (IVUS). Method A total of 60 patients underwent RHC and IVUS examinations. Of these, 27 patients were diagnosed with PAH associated with connective tissue diseases (PAH-CTD group), 18 patients were diagnosed with other types of PAH (other-types-PAH group), and 15 patients were without PAH (control group). The hemodynamics and morphological parameters of pulmonary vessels in PAH patients were assessed using RHC and IVUS. Results There were statistically significant differences in right atrial pressure (RAP), pulmonary artery systolic pressure (sPAP), pulmonary artery diastolic pressure (dPAP), mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) values between the PAH-CTD group, other-types-PAH group, and the control group (P < .05). No statistically significant difference was noticed in pulmonary artery wedge pressure (PAWP) and cardiac output (CO) values between these three groups (P > .05). The mean wall thickness (MWT), wall thickness percentage (WTP), pulmonary vascular compliance, dilation, elasticity modulus, stiffness index β, and other indicators were significantly different between these three groups (P < .05). Pairwise comparison showed that the average levels of pulmonary vascular compliance and dilation in PAH-CTD group and other-types-PAH group were lower than those in control group, while the average levels of elastic modulus and stiffness index β were higher than those in control group. Conclusion Pulmonary vascular performance deteriorates in PAH patients, and the performance is better in PAH-CTD patients than in other types of PAH.

Early Left Ventricular Diastolic Dysfunction in Females with Chronic Hyperprolactinemia: A Doppler Echocardiographic Study.

Despite the myocardial prolactin (PRL) binding activity and the known effect of enhancing contractility in the isolated rat heart, little information is available concerning the cardiovascular consequences of hyperprolactinemia in humans. To elucidate the effects of chronic hyperprolactinemia on cardiac structure and function, twenty-four patients with isolated PRL-secreting adenoma and twenty-four controls underwent a complete mono- and two-dimensional Doppler-echocardiography. Blood pressure and heart rate were similar in the two groups, and no significant differences were observed as to left ventricular (LV) geometry between patients and controls. Resting LV systolic function was normal in patients with hyperprolactinemia, as shown by similar values of fractional shortening and cardiac output. Conversely, hyperprolactinemic patients exhibited a slight impairment of LV diastolic filling, as demonstrated by the prolongation of the isovolumetric relaxation time and the increase of the atrial filling wave of mitral Doppler velocimetry (58 ± 13 vs. 47 ± 8 cm/s, p < 0.05) with a subgroup of females (16%) having a clear diastolic dysfunction, and a worse exercise capacity (6 min walking test 452 ± 70 vs. 524 ± 56; p < 0.05). In conclusion, hyperprolactinemia in humans may be associated with a slight impairment of diastolic function, with an overt diastolic dysfunction in a subgroup of females which correlated with poorer exercise performance, in the absence of significant abnormalities of LV structure and systolic function.

Associated factors and hemodynamic characteristics of resistant hypertension in the elderly.

The purpose of this study was to explore the associated factors and hemodynamic characteristics of resistant hypertension (RHTN) in the elderly. A total of 283 patients aged ≥60 years with hypertension were evaluated by the CNAP™ monitor. Among them, 240 patients were non-RHTN (controlled hypertension with use of three or fewer antihypertensive medications) and 43 patients were RHTN (uncontrolled hypertension despite the concurrent use of ≥3 antihypertensive drugs at optimized doses, including a diuretic, or achieving target blood pressure with the use of ≥4 antihypertensive medications). RHTN was associated with higher body mass index (BMI), longer hypertension duration, and coronary heart disease (p=.004, p<.001, and p=.042, respectively). The mean number of antihypertensive medications was greater in patients with RHTN (p<.001). Hemodynamic analysis revealed higher cardiac output in the RHTN group than in the non-RHTN group, while no difference was observed in systemic vascular resistance. Screening for secondary etiology showed that, among the 43 patients with RHTN, 8 (18.6%) had chronic kidney disease, 8 (18.6%) had obstructive sleep apnea, 4 (9.3%) had primary aldosteronism, 2 (4.7%) had renovascular disease. No significant differences were observed in the cardiac output and systemic vascular resistance values between different causes of RHTN. These findings suggest that higher body mass index, longer hypertension duration, and coronary heart disease emerged as the associated factors of RHTN in the elderly. RHTN is characterized by higher cardiac output. Screening for the possible secondary etiology of RHTN in the elderly patients is necessary and important.

529 PERSPECTIVES ON CARDIAC OUTPUT EVALUATION IN PULMONARY HYPERTENSION PATIENTS UNDERGOING RIGHT HEART CATHETERIZATION

Abstract Background and aim Right heart catheterization (RHC) is the gold standard for the diagnosing and classifying pulmonary hypertension (PH). Cardiac output (CO) and the derived cardiac index (CI) are cornerstones of the hemodynamic evalution allowing pulmonary vascular resistance (PVR) calculation and risk stratification. According to the current European Guidelines, CO should be assessed by the direct Fick method or thermodilution (TD). The indirect Fick (IF) method based on theorically estimated values for VO2, is deemed acceptable bul lacks reliability. Of note, data from the literature on a direct comparison among these three methods used for CO measurement are poor. The objective of our study is to compare CO evaluation by the DF method (DFCO) with CO assessed by IF (IFCO) and TD (TDCO). Secondly, we aimed at assessing the impact of CO estimation by different methods on PVR measurement and therefore on PH hemodynamic classification. This might translate into relevant diagnostic, prognostic and therapeutic implications. Methods 27 patients underwent RHC. Breath-by breath VO2 was measured through a Rudolph mask connected with a two-way respiratory valve to a metabolic cart and averaged over the course of 12 to 15 minutes. DFCO was calculated using the following formula: VO2 (ml/min)/(arteriovenous oxygen content difference×10). For IFCO, the same formula was used with VO2 computed by the Dehmer and the LaFarge-Miettinen formulas. TDCO was obtained through the injection of 10 ml of cold saline solution (0-4°C), in the right atrium and by measuring the temperature variation in the pulmonary artery. Results RHC revealed PH in 23 patients (85%) Average VO2 by Dehmer formula differed significantly from direct measurement (228.9 ± 27.9 ml/min and 204.4 ± 43.6 ml/min respectively; P = 0.017). By using LaFarge formula, mean estimated VO2 differed from direct measurement without reaching statistical significance (185.3 ± 31.9 ml/min and 204.4 ± 43.6 ml/min respectively, P= 0.072). Average CO values did not differ significantly from each other (DFCO 4.2 ± 1.5 L/min; IFCO 4.7 ± 1.3 L/min; TDCO 4.6 ± 1.2 L/min; P=NS for all pairwise comparisons) and showed significant Pearson's correlation. Out of 27 cases, TDCO differed for more (± 0.5 L/min) than 10% as compared to DFCO in 17 (63%). IFCO differed consistently from DFCO in 12 (44%) and IFCO from TDCO in 17 (63%). Despite discrepancies among different CO measurement methods, Cohen's kappa coefficient showed good agreement between the three methods in high PVR (≥3 WU) estimation (IF vs DF 0.79; TD vs DF 0.83 and IF vs TD 0.92 respectively). Conclusions Our results indicate consistent discrepancies among different approaches for VO2 and CO measurement, however this did not impact over PVR assessment and therefore in PH classification. Probably, this is due to the small sample size and the low number of patients (8 of 27) with values around the pathological cut-off for PVR (3 WU). Further studies are needed to better investigate the magnitude of CO measurement discrepancies among different methods on PVR calculation and hemodynamic classification.

Coronary stenosis is a risk marker for impaired cardiac function on cardiopulmonary exercise test

BackgroundCardiac function varies in different ways in ischemic heart disease (IHD). We aimed to evaluate the characteristics of cardiac function on cardiopulmonary exercise test (CPET) in IHD with different coronary stenoses.MethodsTotally 614 patients with IHD were divided into non-obstructive coronary artery disease (NOCAD) (stenosis < 50%), obstructive coronary artery disease (OCAD) (stenosis 50-90%) and severe OCAD ( stenosis > 90%) according to the coronary angiography. And 101 healthy volunteers as controls. All participants performed CPET to assess cardiac function by oxygen uptake (VO2), estimated cardiac output (CO), and heart rate (HR).ResultsGenerally, the values of VO2, CO, and HR in IHD were significantly lower than in healthy volunteers. Among 289 NOCAD, 132 OCAD, and 193 severe OCAD, significantly decreased values of VO2, CO, HR were observed (VO2 peak: 16.01 ± 4.11 vs. 15.66 ± 4.14 vs. 13.33 ± 3.4 mL/min/kg; CO: 6.96 ± 2.34 vs. 6.87 ± 2.37 vs. 6.05 ± 1.79 L/min; HR: 126.44 ± 20.53 vs. 115.15 ± 18.78 vs. 109.07 ± 16.23 bpm, P < 0.05). NOCAD had significantly lower VO2 at anaerobic threshold (-1.35, 95%CI -2.16 - -0.54) and VO2 peak (-2.05, 95%CI -3.18 - -0.93) compared with healthy volunteers after adjustment. All IHD patients were associated with low stroke volume and inefficient gas exchange (P < 0.05).ConclusionIHD with increasing atherosclerotic burdens were associated with impaired cardiac output and chronotropic response on CPET. NOCAD should be given more early prevention and rigorous follow-up.

Perioperative hemodynamic protective assessment of adaptive support ventilation usage in pediatric surgical patients.

The aim of this study was to evaluate the hemodynamic protective effects of perioperative ventilation in pressure-controlled ventilation (PCV) and adaptive support ventilation (ASV) modes based on non-invasive hemodynamic monitoring indicators. The study included 32 patients who were scheduled for planned open abdominal surgery. Depending on the chosen ventilation strategy, patients were included in two groups of PCV mode ventilation (n=14) and ASV mode ventilation (n=18). The hemodynamic effects of the ventilation strategies were assessed by estimated continuous cardiac output (esCCO) and cardiac index (esCCI). Preoperative cardiac output (CO) was 6.1±1.3 L/min in group 1 patients and 6.3±0.8 L/min in group 2 patients, and preoperative cardiac index (CI) was 3.9±0.4 L/min/m2 in group 1 patients and 3.8±0.8 L/min/m2 in group 2 patients. The ejection fraction (EF) in group 1 subjects was 55.4%±0.3%; this rate was 56.5%±0.5% in group 2 subjects. Group 1 patients experienced a 14.7% CO decrease to 5.2±0.7 L/min, a 17.9% CI decrease to 3.2±0.6 L/min/m2 , and a 12.8% mean arterial pressure decrease to 82.3±9.4 mm Hg 30 minutes after the start of surgery. One hour after the start of surgery, the CO mean values of group 2 patients were lower than baseline by 7.9% and differed from the dynamics of patients in group 1, in whom CO was lower than baseline by 13.1%. At the end of the operation, the CO values were lower than baseline by 11.5% and 6.3% in patients of groups 1 and 2, respectively. Our data showed that the changes in EF during and after surgery correlated with CO indicators determined by the esCCO. In our study, perioperative ventilation in ASV mode was more protective than PCV mode and was characterized by lower tidal volume (16.2%) and driving pressure (12.1%). Hemodynamically-controlled mechanical ventilation reduces the negative impact of cardiopulmonary interactions.

Hemodynamic effect of pimobendan following intramuscular and intravenous administration in healthy dogs: A pilot study.

BackgroundPimobendan is widely used for the treatment of dogs with heart failure via the oral route. A new injectable form of pimobendan is now available and its potential usefulness via intravenous route has been recently demonstrated in dogs. However, the cardiovascular effects of intramuscular (IM) administration of injectable pimobendan have not been investigated yet.HypothesisIM administration of pimobendan may have the same hemodynamic effect as the IV route.MethodsSix healthy Beagle dogs underwent a placebo-controlled double-blind crossover study. The early cardiovascular effects after a single dose of IM and IV injections of pimobendan (0.2 ml/kg; Pimo IM and Pimo IV, respectively) were compared to the same volume of IM placebo (Saline IM) in anesthetized dogs. Clinical [heart rate (HR) and blood pressure (BP)] and echocardiographic hemodynamic parameters [left ventricular (LV) inflow waveforms of diastolic early wave (eV), atrial systolic wave (aV), diastolic early mitral ring velocity (e′), peak velocity (pV), stroke volume (SV), cardiac output (CO), and systemic vascular resistance (SVR)] were monitored with 15 min intervals for 120 min.ResultsDiastolic BP decreased significantly at 30 min in Pimo IM compared to Saline IM. Mean eV and CO values significantly increased from 75 min, e′ from 60 min, pV from 75 min, and SV from 15 to 120 min, whereas SVR significantly decreased at 30–60 min in Pimo IM compared to those of Saline IM (P < 0.05). Compared with the Pimo IV, eV and pV were significantly lower at 30–60 min (P < 0.05) while SV was significantly higher at 90–105 min in Pimo IM (P < 0.05). Other hemodynamic parameters (BP, HR, SVR, CO, e′, and E/e′) did not significantly change between Pimo IM and IV.ConclusionsThe hemodynamic effect of pimobendan following IM and IV injection was described. Our results suggested that IM administration of pimobendan is equally comparable and possibly interchangeable with IV administration. This warrant further studies to investigate the clinical effectiveness of IM pimobendan in treating dogs with congestive heart failure or in heart failure cases unable to receive IV or oral administration.

Sigmoid isostiffness-lines: An in-vitro model for the assessment of aortic stenosis severity.

IntroductionThe aortic valve opening area (AVA), used to quantify aortic stenosis severity, depends on the transvalvular flow rate (Q). The currently accepted clinical echocardiographic method assumes a linear relation between AVA and Q. We studied whether a sigmoid model better describes this relation and determined “isostiffness-lines” across a wide flow spectrum, thus allowing building a nomogram for the non-invasive estimation of valve stiffness.MethodsBoth AVA and instantaneous Q (Qinst) were measured at 10 different mean cardiac outputs of porcine aortic valves mounted in a pulsatile flow loop. The valves' cusps were chemically stiffened to obtain three stiffness grades and the procedure was repeated for each grade. The relative stiffness was defined as the ratio between LV work at grade with the added stiffness and at native stiffness grade. corresponding to the selected of the highest 3 and 5 cardiac output values was predicted in K-fold cross-validation using sequentially a linear and a sigmoid model. The accuracy of each model was assessed with the Akaike information criterion (AIC).ResultsThe sigmoid model predicted more accurately (AIC for prediction of AVA with of the 3 highest cardiac output values: –1,743 vs. –1,048; 5 highest cardiac output values: –1,471 vs. –878) than the linear model.ConclusionThis study suggests that the relation between AVA and Q can be better described by a sigmoid than a linear model. This construction of “isostiffness-lines” may be a useful method for the assessment of aortic stenosis in clinical echocardiography.

Phenotyping exercise limitation of patients with Interstitial Fibrosing Lung Disease: the importance of exercise hemodynamics

Introduction and objectiveLeft-heart dysfunction and pulmonary vasculopathy are increasingly recognized as contributing factors of exercise capacity limitation in interstitial fibrosing lung disease (IFLD). Moreover, the clinical significance of exercise pulmonary hypertension (ePH) in pulmonary and cardiac diseases has been documented, representing a risk factor for decreased exercise capacity and survival, progression to resting pulmonary hypertension (PH) and overall clinical worsening.We conducted a prospective study aiming at: (a) assessing the prevalence of PH and ePH in a cohort of 40 functionally limited patients with IFLD, (b) determining the post-capillary (postC) or pre-capillary (preC) etiology of either PH or ePH in this cohort, and (c) examining the correlations between invasively and non-invasively measured exercise variables among hemodynamic groups. Patients and methods40 IFLD patients underwent cardiopulmonary evaluation, including: clinical examination, lung function tests, 6-minute walking test, heart ultrasonography, cardiopulmonary exercise test and, finally, right heart catheterization (RHC). Resting hemodynamic evaluation was followed by the exercise protocol proposed by Herve et al, using a bedside cycle ergometer in the supine position. Abnormal elevation of mean pulmonary artery pressure (mPAP) above 30mmHg during exercise, with respect to abnormal elevation of cardiac output (CO) below 10 L/min (mPAP–CO ratio ⩾3 mmHg·min·L−1) was used to define ePH (Herve et al, 2015). Secondary hemodynamic evaluation involved detection of abnormal pulmonary arterial wedge pressure (PAWP) increase at peak exercise in relation to CO. Specifically, ΔPAWP/ΔCO >2 mmHg/L per minute determined an abnormal PAWP elevation (Bentley et al, 2020). ResultsAmong the 40-patient cohort, 25% presented postC PH, 37.5% preC PH, 27.5% ePH, with the remaining 10% recording normal hemodynamics. PAWP evaluation during exercise revealed a postC etiology in 4 out of the 11 patients presenting ePH, and a postC etiology in 6 out of the 15 patients presenting resting preC PH. Mean values of non-invasive variables did not display statistically significant differences among hemodynamic groups, except for: diffusing capacity for carbon monoxide (DLCO), carbon monoxide transfer coefficient (KCO) and the ratio of functional vital capacity to DLCO (FVC%/DLCO%), which were lower in both ePH and PH groups (p < 0.05). Resting values of CO, cardiac index (CI), stroke volume (SV) and pulmonary vascular compliance (PVC) were significantly impaired in ePH, preC-PH and postC-PH groups when compared to the normal group. ConclusionsBoth PH and ePH were highly prevalent within the IFLD patient group, suggesting that RHC should be offered more frequently in functionally limited patients. Diffusion capacity markers must thus guide decision making, in parallel to clinical evaluation. ePH was associated to lower resting CO and PVC, in a similar way to resting PH, indicating the relevance of cardiopulmonary function to exercise limitation. Finally, the use of the ΔPAWP/ΔCO>2 criterion further uncovered PH of postcapillary etiology, highlighting the complexity of hemodynamics in IFLD.ClinicalTrials.gov ID: NCT03706820

High Arterial Lactate Levels after Hepatic Resection Are Associated with Low Oxygen Delivery and Predict Severe Postoperative Complications.

High End-Surgery Arterial Lactate Concentration (ES-ALC) predicts poor outcome after hepatectomy. The aim of this study was to identify intraoperative hemodynamic parameters predicting high ES-ALC during elective liver resection. Patients who underwent liver resection between 2017 and 2018, under FloTrac/EV1000TM hemodynamic monitoring, were included. The ES-ALC cutoff best predicting severe postoperative complications was identified. Association between high ES-ALC and preoperative and intraoperative variables was assessed. 108 patients were included; 90-day mortality was 0.9% and severe morbidity 14.8%. ES-ALC cutoff best discriminating severe complications was 5.05 mmol/L. Patients with ES-ALC > 5.0 mmol/L had a relative risk of severe complications of 2.8% (p = 0.004). High ES-ALC patients had longer surgery and ischemia duration, larger blood losses and higher requirements of fluids and blood transfusions. During surgery, hemoglobin concentration and oxygen delivery (DO2) decreased more significantly in patients with high ES-ALC, although they had similar values of stroke volume and cardiac output to those of other patients. At multivariate analysis, surgery duration and lowest recorded DO2 value were the strongest predictors of high ES-ALC. ES-ALC > 5.0 mmol/L in elective liver resection predicts postoperative morbidity and is essentially driven by the impaired DO2. Timely correction of blood losses might prevent the ES-ALC increase.

Transpulmonary ultrasound dilution is an acceptable technique for cardiac output measurement in anesthetized pigs

To evaluate cardiac output (CO) measurements using transpulmonary ultrasound (TPUD) technology and compare results with those of the gold standard, pulmonary arterial catheter thermodilution (PACTD), in 6 healthy anesthetized pigs during acute hemodynamic changes caused by manipulation of the blood volume. 6 healthy male Landrace pigs. Over a period of 1 week, pigs were anesthetized with isoflurane, mechanically ventilated, and underwent instrumentation in dorsal recumbency. They were subjected to sequential experimental states during which the blood volume was manipulated so that the animals transitioned from normovolemia to hypovolemia (20% and 40% of blood volume depletion), back to normovolemia (autologous blood transfusion), and then to hypervolemia (following colloid bolus). During each volume state, CO measurements were compared between TPUD and PACTD. The mean ± SD relative bias between TPUD and PACTD was 7.71% ± 21.2% with limits of agreement -33.9% to 49.3%, indicating TPUD slightly underestimated CO values, compared with values obtained with PACTD. The mean ± SD of the bias between the 2 methods was 0.13 ± 0.5 L/min. Only 5 of 36 (13.9%) TPUD CO measurements had an absolute value of relative bias > 30%. The percentage error calculated for TPUD was 29.4%. Results suggested that TPUD measurements have acceptable agreement with PACTD measurements. Moreover, TPUD exhibits promising potential in being used interchangeably with PACTD for future hemodynamic research involving swine as species of interest.

Hemodynamic assessment in patients with preterm premature rupture of the membranes (pPROM)

ObjectiveThe aim of this study was to assess the hemodynamic differences in women with pPROM versus physiological pregnancies. Study designThis was a prospective case control study of 15 patients with pPROM and 45 controls. Patients and controls were submitted at enrollment to a non-invasive hemodynamic evaluation with UltraSonic Cardiac Output Monitor (USCOM), and to blood tests to check white blood cells count and C-reactive protein (CRP) levels. We followed pPROM patients until delivery noting fetal/neonatal and maternal unfavorable outcomes (maternal fever, APGAR 1′ and 5′< 7, stillbirth). ResultsPatients with pPROM showed higher values of cardiac output (9.1 ± 2.3 vs 7.1 ± 0.85, p < 0.01), lower systemic vascular resistances (792.1 ± 162 vs 1006.2 ± 110.7, p < 0.01), higher minute distance (32.3 ± 7.8 vs 25 ± 2.8, p < 0.01), lower Potential to Kinetic Energy Ratio (16.5 ± 5.3 vs 22.4 ± 6.8, p < 0.01), higher heart rate (97.5 ± 15.4 vs 82.4 ± 12, p < 0.01) and higher oxygen delivery (1313.2 ± 325.8 vs 1080.7 ± 151.8, p < 0.01) vs. controls. Six out of 15 pPROM patients had an unfavorable outcome. There were no significant differences in CRP levels and WBC count at admission in the two pPROM subgroups, whereas maternal hemodynamics was characterized by lower SVR (718 ± 72 vs 863 ± 123, p = 0.02) in subsequently complicated patients. ConclusionsMaternal hemodynamics is altered in pPROM patients, with a lower Systemic Vascular Resistance and higher Cardiac Output vs. controls. This hyperdynamic circulation appears to anticipates the changes of serum markers of inflammation (CRP, WBC count) and seems to be more pronounced at admission in pPROM patients developing unfavorable outcomes.

Рівень функціонування адаптаційних механізмів серцево-судинної системи в дітей із синкопе різного ґенезу

changes which in turn depend on the basic level of functional capabilities of the cardiovascular system and its adaptation mechanisms that determine the intensity and duration of adaptive responses. Purpose - to determine the level of cardiovascular adaptations in children with syncope; to assess their relationship with some clinical, anamnestic and instrumental parameters. Materials and methods. A total of 81 children with vasovagal syncope, 25 with syncope due to orthostatic hypotension, 19 with cardiogenic syncope (aged 8-17 years) were included in our study. The control group included 41 healthy children. All patients underwent a clinical and functional examination of the cardiovascular system to determine the level of its adaptative mechanisms. Results. Children with vasovagal syncope and syncope due to orthostatic hypotension had significantly higher values of cardiac output and systolic blood volume compared to control group (p&lt;0.05), which indicated the intensity of pumping ability of the heart. Children with syncope due to orthostatic hypotension had marked decrease in the efficiency of the heart muscle, as low values of left ventricular rate, circulatory efficiency and cardiac index compared with healthy individuals (p&lt;0.05), as well as the trend to economize hemodynamic responses, as indicated by a significant difference between the values of the Robinson index, a decreased systolic index and the index of functional changes compared with those without syncope (p&lt;0.05). Children with cardiogenic syncope had a significantly reduced the circulatory efficiency coefficient (p&lt;0.05). Significant correlations were detected between the parameters of a series of integrative indicators of the adaptive mechanisms of the cardiovascular system and anamnestic, clinical, and the reports of instrumental studies in children with syncope. Conclusions. Despite the fact that children with syncope of various types had normal values for most cardiovascular indicators at rest, the tension of pumping capacity of the heart was detected, the efficiency of the cardiac muscle and circulatory efficiency were reduced, which are signs of reduced compensatory responses in children of the study groups determined. The results of the study confirm the close combination of pathogenetic mechanisms of syncope with a decrease in the adaptive mechanisms of the cardiovascular system of this category of patients. The research was carried out in accordance with the principles of the Declaration of Helsinki. The research protocol was approved by the Local Ethics Committee of the institutions mentioned in the work. Informed consent of the children’s parents was obtained for the research. No conflict of interests was declared by the authors. Key words: children, syncope, cardiovascular adaptations.

Correlation of Cardiac Output by Arterial Contour-Derived Cardiac Output Monitor Versus Pulmonary Artery Catheter in Liver Transplant: Experience at an Indian Center

Objective:Arterial pulse-derived cardiac output monitors are routinely employed to guide hemodynamic management during liver transplant surgery. In this study, we sought to assess the reliability by evaluating the agreement of the cardiac output measured by the FloTrac Vigileo versus pulmonary artery catheter (continuous cardiac output) at specified times during liver transplant.Methods:Liver transplant database with cardiac output values measured by FloTrac Vigileo and continuous cardiac output was analyzed retrospectively at a tertiary care hospital. Data were compared at T0: baseline, T1: 1 hour in dissection phase, T2: anhepatic phase, T3: portosystemic shunt, T4: reperfusion, T5: 1 hour after reperfusion, and T6: skin closure. Statistical analysis was done using Bland–Altman analysis and percentage error (<30%) to assess the agreement between cardiac output measured by 2 techniques, Lin’s concordance correlation coefficient for quantifying the agreement and 4-quadrant plots to compare the trends of cardiac output.Results:Bland–Altman analysis showed mean cardiac output ± standard deviation L min-1 (95% CI) at T0: 0.2 ± 2.09 (−3.9 to 4.3), T1: 0.53 ± 3.0 (−5.4 to 6.4), T2: 0.47 ± 2.1(−3.7 to 4.6), T3: 0.31 ± 1.9 (−3.4 to 4.0), T4: 0.44 ± 2.15 (−3.8 to 4.7), T 5:0.69 ± 1.9. (−2.9 to 4.3), and at T6: 0.43 ± 2.25 (−4.0 to 4.8). Percentage error was 44%-72% and concordance correlation coefficient was poor (<0.65) at all points.Conclusions:There is poor agreement between the cardiac output measured by FloTrac and pulmonary artery catheter among liver transplant recipients. The need for superior hemodynamic monitoring is mandated in liver transplant.

A dynamic blood flow model to compute absorbed dose to circulating blood and lymphocytes in liver external beam radiotherapy

We have developed a novel 4D dynamic liver blood flow model, capable of accurate dose estimation to circulating blood cells during liver-directed external beam radiotherapy, accounting for blood recirculation and radiation delivery time structure. Adult male and adult female liver computational phantoms with detailed vascular trees were developed to include the hepatic arterial, hepatic portal venous, and hepatic venous trees. A discrete time Markov Chain approach was applied to determine the spatiotemporal distribution of 105 blood particles (BP) in the human body based on reference values for cardiac output and organ blood volumes. For BPs entering the liver, an explicit Monte Carlo simulation was implemented to track their propagation along ∼2000 distinct vascular pathways through the liver. The model tracks accumulated absorbed dose from time-dependent radiation fields with a 0.1 s time resolution. The computational model was then evaluated for 3 male and 3 female patients receiving photon (VMAT and IMRT) and proton (passive SOBP and active PBS) treatments. The dosimetric impact of treatment modality, delivery time, and fractionation on circulating blood cells was investigated and quantified using the mean dose (), V >0Gy, V >0.125Gy, and D 2%. Average reductions in V >0Gy, V >0.125Gy and D 2% of 45%, 6%, 53%, 19% respectively, were observed for proton treatments as compared to photon treatments. Our simulation also showed that V >0Gy, V >0.125Gy, and D 2% were highly sensitive to the beam-on time. Both V >0Gy and V >0.125Gy increased with beam-on time, whereas D 2% decreased with increasing beam-on time, demonstrating the tradeoff between low dose to a large fraction of blood cells and high dose to a small fraction of blood cells. Consequently, proton treatments are not necessarily advantageous in terms of dose to the blood simply based on integral dose considerations. Instead, both integral dose and beam-on time can substantially impact relevant dosimetric indices.

Hemodynamic Monitoring by Smartphone-Preliminary Report from a Comparative Prospective Observational Study.

Background: Advanced hemodynamic monitoring supports making therapeutic decisions in critically ill patients. New technologies, including mobile health, have been introduced into the hemodynamic monitoring armamentarium. However, each monitoring method has potential limitations—content, technical and organizational. The aim of this study was to assess the comparability between measurements obtained with two arterial pressure cardiac output methods: Capstesia™ smartphone hemodynamic software (CS) and LiDCO Rapid™ uncalibrated hemodynamic monitor (LR). Methods: The initial analysis included 16 patients in the period 06–09 2020 without limitations that could make the results obtained unreliable. Eighty pairs of cardiac output measurements were obtained. The comparability of cardiac output results obtained with both methods was assessed using the Spearman’s rank correlation coefficient (R), the intra-class correlation (CCC) and the Bland–Altman curves analysis (B-A). Results: The median (IQR) cardiac output measured with CS and LR were 4.6 (3.9–5.7) and 5.5 (4.6–7.4) L min−1, respectively. In the B-A analysis, CS cardiac output values were on average 1.2 (95% CI −2.1–4.4) L min-1 lower than LR values. The correlation between cardiac output with CS and LR was moderate (r = 0.5; p = 0.04). After adjusting for the presence of the dicrotic notch on the pulse waveform, in the group of eight patients with a visible dicrotic notch, the CS and LR results differed by only 0.1 (95% CI −0.8–1.1) L min−1, the correlation between CS and LR was close to complete (r = 0.96; p < 0.001), and the percentage error was 40%, with a CCC-CS of 0.98 (95% CI 0.95–0.99). Conclusions: The CapstesiaTM smartphone software can provide an alternative method of cardiac output assessment in patients meeting arterial pressure cardiac output evaluation criteria with a clearly discernible dicrotic notch on the arterial pulse pressure waveform. It is necessary to confirm the obtained observations on a larger group of patients; however, it may potentially make objective hemodynamic measurements ubiquitous in patients with invasive arterial pressure monitoring with a clearly discernible dicrotic notch.

Modern gold standard of cardiac output measurement- A simplified bedside measurement of individual oxygen uptake in the cath lab.

Cardiac output (CO) measurements employing the direct Fick principle represent the gold standard in right-sided heart catheterization (RHC). The current widespread approach in hemodynamic workup however uses the indirect Fick principle with assumed values for oxygen uptake (VO2) leading to incorrect CO values in up to 25% of patients. We have tested a contemporary breath-by-breath gas analyzer that allows precise real-time measurements of VO2 with appropriate time and effort to serve the direct Fick principle. By means of a small and mobile metabolic cart assembled with widely used components of a standard spiroergometer, we performed bedside measurements of individual VO2. In 33 unselected, consecutive patients with various indications for RHC we compared CO values derived from indirect vs. direct Fick calculations. In 28 of the 33 patients, VO2 measurements were completed with a plausible dataset within a median of 3.2 (interquartile range 2.8-6.2) min. In nine of the 28 patients, CO values based on measured VO2 values differed by more than 20% from CO calculations based on assumed VO2 values with value deviations scattering over a broad range in both directions (maximally +52% to minimally-46%). The bedside measurement of VO2 for gold standard CO determination is technically feasible within a few min and can thus be easily included in any RHC protocol. As modern therapy for numerus indications demand a precise upfront measurement of hemodynamics, our method might help to correctly identify patients for costly therapies.