Changes In Stroke Volume Research Articles

Acute changes in right ventricular geometry and function following transcatheter tricuspid valve interventions

Abstract Background Little is known about acute changes in right ventricular (RV) function and geometry following transcatheter tricuspid edge-to-edge repair (T-TEER) or transcatheter tricuspid valve replacement (TTVR). Pressure-strain-volume loop-derived myocardial work metrics showed associations with myocardial energetics and contractility in conditions accompanied by volume overload, suggesting their potential utility in patients with tricuspid regurgitation (TR). Purpose To define acute changes in RV volumes and RV myocardial work following T-TEER and TTVR using conventional and pressure-strain-volume derived RV work metrics. Methods In this multicenter, observational study, 3D echocardiographic datasets and invasively acquired RV pressures were collected before and after transcatheter tricuspid valve procedure. Using dedicated software (ReVISION, Argus Cognitive) 3D RV volumes and strains were quantified and decomposed to longitudinal, radial and anterio-posterior motion. Forward stroke volume (SV) was calculated by subtracting TR volumes from RV 3D end-diastolic volume (EDV) and end-systolic volume (ESV) difference. Three-dimensional pressure-strain-volume loops were constructed and global RV work-index (RV-Wi) was calculated. Changes in RV parameters before and after the intervention were compared using paired-samples t test. Results Of 37 patients included in this study (65% male), 20 underwent T-TEER and 17 underwent TTVR. Compared to T-TEER patients, patients undergoing TTVR had higher prevalence of torrential TR at baseline but also achieved a higher reduction in TR volumes after the intervention (44 ± 11 ml vs 60 ± 16ml; p = 0,001). Following T-TEER there was a significant reduction in RV EDV (240 ± 93 ml vs 200 ± 80 ml; p < 0.001) and increase in SV (55 ± 34 ml vs 68 ± 26 ml; p = 0.036). Following TTVR there was a significant increase in RV ESV (121 ± 46 vs 146 ± 48, p = 0.003) and no significant change in SV (47 ± 24 ml vs 55 ± 20 ml; p = 0.143). There was significant reduction in RV strain and ejection fraction (EF) (all p < 0.001) primarily driven by reduction of radial motion component in both groups. RV-Wi increased in 35% (7/20) of T-TEER patients and in 18% of (3/17) TTVR patients. Conclusion An acute reduction in RV EF was observed in all patients and was mainly caused by decrease in RV EDV in T-TEER patients and increase in RV ESV in TTVR patients. Despite decrease of conventional metrics of RV function in both groups, an increase in RV-Wi was observed in 27% of all patients.Baseline and follow-up characteristicsCentral Figure

The relative contribution of hemodynamic parameters to blood pressure decrease in classical orthostatic hypotension.

We studied the relative contributions of total peripheral resistance (TPR), stroke volume (SV) and heart rate (HR) to low blood pressure in classical orthostatic hypotension (cOH) on group and individual levels. We retrospectively analyzed tilt test records from cOH patients and age/sex-matched controls. We quantified relative effects of HR, SV and TPR on mean arterial pressure (MAP) with the log-ratio method. We studied relations of changes of HR, SV or TPR with the change of MAP across patients and variability of contributions of HR, SV and TPR to MAP. We also explored neurogenic vs. nonneurogenic causes. MAP responded to tilt with a decrease in patients (n = 80) and an increase in controls (n = 80). A too small TPR-increase contributed most to cOH, followed by a too large SV-decrease; both effects were partially corrected by a larger increase of HR. Only TPR changes consistently affected MAP change in patients and controls. TPR decreased almost exclusively in patients, most in those with severe cOH. Contributions of HR, SV and TPR to MAP did not differ between probable neurogenic and nonneurogenic causes. HR, SV and TPR all contributed to cOH, with a key role for TPR; a decrease of TPR was almost unique to patients and may be due to hyperventilation. The lack of differences between neurogenic and nonneurogenic causes needs further study.

Non-invasive hemodynamic monitoring during initiation of positive airway pressure treatment in patients with obstructive sleep apnea: a feasibility study

BackgroundThe association of obstructive sleep apnea (OSA) with cardiovascular morbidity has been repeatedly reported in numerous studies and argues for treatment initiation even in the absence of significant day time sleepiness. While the long-term consequences of positive airway pressure (PAP) treatment on OSA related comorbidities like secondary hypertension are based on substantial clinical evidence, less is known about the immediate hemodynamic effects.MethodsThis study tried to investigate the impact of PAP treatment on different hemodynamic parameters in 48 patients with OSA by extending the standard polysomnographic assessment with non-invasive hemodynamic monitoring using impedance cardiography (ICG). On two consecutive nights under diagnostic and therapeutic conditions, polysomnographic and hemodynamic data were acquired. In addition, we subdivided the participants according to their treatment related change in stroke volume (SV) and assigned the hemodynamic measurements to the corresponding sleep stage.ResultsComparing both conditions, a non-statistically significant decrease in SV and cardiac output (CO) was observed for all participants. Treatment initiation was associated with a statistically significant prolongation of the pre-ejection period (PEP) for the entire study population (p = 0.001) and the subgroup with decreasing SV (p = 0.008). In addition, systolic blood pressure (SBP) (p = 0.026) and pulse pressure (PP) (p = 0.041) were lowered significantly for patients with a therapeutically reduced SV under treatment conditions. A higher BMI (p = 0.020) and a more pronounced reduction of the respiratory distress index (RDI) (p = 0.030) and the arousal-index (p = 0.021) were observed for patients with decreasing SV. Correlational analysis revealed a negative relationship between the diagnostic values for both SBP (r=-0.324, p = 0.025) and PP (r=-0.407, p = 0.004) with the change in SV and a positive correlation with the change of the SBP (r = 0.317, p = 0.028) for all participants.ConclusionsTo conclude, our results indicate that treatment with a PAP device in patients with OSA can lead to a decrease in SV which is associated with a lowering of the SBP. This may be caused by a reduced sympathetic tone due to less respiratory events and an improved sleep profile.

Examining temporal changes in model-optimized parameters using longitudinal hemodynamic measurements

BackgroundWe previously applied hemodynamic data to personalize a mathematical model of the circulation expressed as physically interpretable parameters. The aim of this study was to identify patterns in the data that could potentially explain the estimated parameter changes. This included investigating whether the parameters could be used to track the effect of physical activity on high blood pressure. Clinical trials have repeatedly detected beneficial changes in blood pressure after physical activity and uncovered changes in lower level phenotypes (such as stiffened or high-resistance blood vessels). These phenotypes can be characterized by parameters describing the mechanical properties of the circulatory system. These parameters can be incorporated in and contextualized by physics-based cardiovascular models of the circulation, which in combination can become tools for monitoring cardiovascular disease progression and management in the future.MethodsClosed-loop and open-loop models of the left ventricle and systemic circulation were previously optimized to data from a pilot study with a 12-week exercise intervention period. Basal characteristics and hemodynamic data such as blood pressure in the carotid, brachial and finger arteries, as well as left-ventricular outflow tract flow traces were collected in the trial. Model parameters estimated for measurements made on separate days during the trial were used to compute parameter changes for total peripheral resistance, systemic arterial compliance, and maximal left-ventricular elastance. We compared the changes in these cardiovascular model-based estimates to changes from more conventional estimates made without the use of physics-based models by correlation analysis. Additionally, ordinary linear regression and linear mixed-effects models were applied to determine the most informative measurements for the selected parameters. We applied maximal aerobic capacity (measured as VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{VO2max}$$\\end{document}) data to examine if exercise had any impact on parameters through regression analysis and case studies.Results and conclusionsParameter changes in arterial parameters estimated using the cardiovascular models correlated moderately well with conventional estimates. Estimates based on carotid pressure waveforms gave higher correlations (0.59 and above when p<0.05\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$<0.05$$\\end{document}) than those for finger arterial pressure. Parameter changes over the 12-week study duration were of similar magnitude when compared to short-term changes after a bout of intensive exercise in the same parameters. The short-term changes were computed from measurements made immediately before and 24 h after a cardiopulmonary exercise test used to measure VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{VO2max}$$\\end{document}. Regression analysis indicated that changes in VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{VO2max}$$\\end{document} did not account for any substantial amount of variability in total peripheral resistance, systemic arterial compliance, or maximal left-ventricular elastance. On the contrary, changes in stroke volume contributed to far more explained variability. The results suggest that more research is required to be able to accurately track exercise-induced changes in the vasculature for people with pre-hypertension and hypertension using lumped-parameter models.

Non-Invasive Electrical Cardiometry versus Echocardiography for Assessment of Patent Ductus Arteriosus Hemodynamic Response to Medical Treatment in Preterm Neonates

Abstract Background Patent ductus arteriosus (PDA) poses a diagnostic and a therapeutic dilemma for neonatologists. Although echocardiography (Echo) has been the gold standard diagnostic tool for PDA, it requires a trained cardiologist or neonatologist to perform and it is usually not available around the clock. Echo provides also a single rather than continuous assessment of the sick neonates, whose hemodynamic status changes quickly. Electrocardiometry (EC) is a new device for continuous hemodynamic monitoring of neonates. Aim of the Work To evaluate the accuracy and precision of EC in comparison to ECHO in assessment of PDA response to treatment in preterm neonates. Patients and Methods This diagnostic accuracy study was conducted in the neonatal intensive care units (NICUs) of Children’s Hospital of Ain Shams University, Cairo, between (1/5/2021 and 31/3/2022). The study was approved by the ethical committee of Ain Shams University. Preterm neonates&amp;lt;35weeks gestational age admitted during the study period were eligible for enrollment. Neonates with hemodynamically non-significant PDA and those with other congenital anomalies were excluded. A baseline echo and electrical cardiometry were done at the time of enrollment and on day 5. Results Forty neonates were enrolled (27 females, 13 males). Closure rate of oral ibuprofen was 100% (39/39) while paracetamol failed to close the PDA in one patient (closure success 0%). Echo and EC didn’t agree upon the tested parameters (stroke volume (SV), cardiac index (CI), ejection fraction (EF), cardiac output (CO) but agreed in measuring heart rate (HR). In patients with inotropes, Echo detected significant changes in CO (p = 0.044) and CI (p = 0.047) but no changes in SV, EF and HR (p = 0.41, 0.506 &amp; 0.105 respectively). In patients who needed mechanical ventilation, Echo detected significant changes in CI (p = 0.008), CO (0.006) and SV (0.042). No changes were detected in any parameter by EC in patients who needed either inotropes or mechanical ventilation (p &amp;gt; 0.05 in all parameters). Conclusion While EC is safe and an easy to apply device, our results show that electrocardiometry is not as accurate as the echocardiography in predicting the hemodynamic changes that might correspond to the closure of PDA in preterm neonates with hemodynamically significant PDA.

Acute Effects of Skeletal Muscle Electrical Stimulation on Central and Lower Extremity Hemodynamics.

Belt electrode-skeletal muscle electrical stimulation (B-SES) is a treatment prescribed for individuals with difficulty performing exercise therapy that improves muscle strength, exercise tolerance, and glucose metabolism. However, the effects of B-SES on the hemodynamics of the central and lower extremity conduit arteries have not been studied. Therefore, this study compared the acute effects of B-SES on the central and lower extremity conduit arteries in healthy young males. This randomized crossover study included nine healthy young males (mean age: 21.0±1.1 years). Participants were assigned to the following experimental conditions, with a washout period of one week: condition 1 included 20 min of electrical stimulation of the lower extremity at the participant's sensation threshold intensity (Sham, n=9)and condition 2included 20 min of electrical stimulation of the lower extremity at the maximum intensity the participant can tolerate (B-SES, n=9). The heart rate (HR), stroke volume (SV), cardiac output (CO), mean arterial pressure (MAP), and total peripheral vascular resistance (TPR) were measured as central hemodynamics. The hemodynamics of the lower extremity conduit arteries were measured and calculated for the shallow femoral artery (SFA), including vessel diameter, mean blood flow velocity (MBFV), shear rate (SR), and mean blood flow (MBF) rate. These indices were measured before stimulation (Pre), 10 min after the start of stimulation (Stimulating), and immediately after the end of stimulation (Post). These indices were compared using a repeated two-way analysis of variance. In B-SES, HR (Pre: 63.2±8.6; Stimulating: 73.7±6.9; Post: 70.0±4.2 bpm, p<0.01), CO (Pre: 5.1±1.0; Stimulating: 6.5±1.5, p<0.01; Post: 6.3±1.2 L/min, p=0.02), and MAP (Pre: 104.0±11.5; Stimulating: 116.4±10.8, p<0.01; Post: 109.6±9.7 mmHg, p=0.02) increased significantly. In addition, B-SES significantly increased MBFV (Pre: 19.2±4.0; Stimulating: 50.5±14.9; Post: 30.1±4.0 cm/s, p<0.01), SR (Pre: 118.9±28.8; Stimulating: 302.7±91. 2, p<0.01; Post: 182.1±70.1/s, p=0.02), and MBF (Pre: 382.0±61.5; Stimulating: 1009.6±321.4; Post: 626.8±176.6 mL/min, p<0.01). However, there were no significant changes in SV and TPR. The findings of this study indicatethat B-SES in healthy young males increases CO without increasing SV or TPR and improves the MBFV and SR in the SFA.

The Hemodynamic Changes Induced by Lung Recruitment Maneuver to Predict Fluid Responsiveness in Children during One Lung Ventilation-A Prospective Observational Study.

The prediction of fluid responsiveness in critical patients helps clinicians in decision making to avoid either under- or overloading of fluid. This study was designed to determine whether lung recruitment maneuver (LRM) would have an effect on the predictability of fluid responsiveness by the changes of hemodynamic parameters in pediatric patients who were receiving lung-protective ventilation and one-lung ventilation (OLV). A total of 34 children, aged 1-6 years old, scheduled for heart surgeries via right thoracotomy were enrolled. Patients were anesthetized and OLV with lung-protection ventilation settings was established, and then, positioned on left lateral decubitus. LRM and volume expansion (VE) were performed in sequence. Heart rate (HR), systolic arterial pressure (SAP), mean arterial pressure (MAP) diastolic arterial pressure (DAP), stroke volume (SV), stroke volume variation (SVV), and pulse pressure variation (PPV) were recorded via an A-line based monitor system at the following time points: before and after LRM (T1 and T2) and before and after VE (T3 and T4). An increase in stroke volume (SV) or mean arterial pressure (MAP) of ≥10% following fluid loading identified fluid responders. The predictability of fluid responsiveness by the changes of SV (ΔSVLRM) and MAP (ΔMAPLRM) after LRM and VE were statistically evaluated by receiver operating characteristic curves [area under the curves (AUC)]. SVs in all patients were significantly decreased after LRM (p < 0.01) and then, increased and returned to baseline after VE (p < 0.01). In total, 16 out of 34 patients who were fluid responders had significantly lower SV after LRM compared to that in fluid non-responders. The area under the receiver operating characteristic curves for ΔSVLRM was 0.828 (95% confidence interval [CI], 0.660 to 0.935; p < 0.001) and it indicated that ΔSVLRM was able to predict the fluid responsiveness of pediatric patients. MAPs in all patients were also decreased significantly after LRM, and 12 of them fell into the category of fluid responders after VE. Statistically, ΔMAPLRM did not predict fluid responsiveness when LRM was considered as an influential factor (p = 0.07). ΔSVLRM, but not ΔMAPLRM, showed great reliability in the prediction of the fluid responsiveness following VE in children during one-lung ventilation with lung-protective settings. ChiCTR2300070690.

Physiologic validation of the Compensatory Reserve Metric obtained from pulse oximetry: A step toward advanced medical monitoring on the battlefield.

The Compensatory Reserve Metric (CRM) provides a time sensitive indicator of hemodynamic decompensation. However, its in-field utility is limited because of the size and cost-intensive nature of standard vital sign monitors or photoplethysmographic volume-clamp (PPG VC ) devices used to measure arterial waveforms. In this regard, photoplethysmographic measurements obtained from pulse oximetry may serve as a useful, portable alternative. This study aimed to validate CRM values obtained using pulse oximeter (PPG PO ). Forty-nine healthy adults (25 females) underwent a graded lower body negative pressure (LBNP) protocol to simulate hemorrhage. Arterial waveforms were sampled using PPG PO and PPG VC . The CRM was calculated using a one-dimensional convolutional neural network. Cardiac output and stroke volume were measured using PPG VC . A brachial artery catheter was used to measure intra-arterial pressure. A three-lead electrocardiogram was used to measure heart rate. Fixed-effect linear mixed models with repeated measures were used to examine the association between CRM values and physiologic variables. Log-rank analyses were used to examine differences in shock determination during LBNP between monitored hemodynamic parameters. The median LBNP stage reached was 70 mm Hg (range, 45-100 mm Hg). Relative to baseline, at tolerance, there was a 47% ± 12% reduction in stroke volume, 64% ± 27% increase in heart rate, and 21% ± 7% reduction in systolic blood pressure ( p < 0.001 for all). Compensatory Reserve Metric values obtained with both PPG PO and PPG VC were associated with changes in heart rate ( p < 0.001), stroke volume ( p < 0.001), and pulse pressure ( p < 0.001). Furthermore, they provided an earlier detection of hemodynamic shock relative to the traditional metrics of shock index ( p < 0.001 for both), systolic blood pressure ( p < 0.001 for both), and heart rate ( p = 0.001 for both). The CRM obtained from PPG PO provides a valid, time-sensitized prediction of hemodynamic decompensation, opening the door to provide military medical personnel noninvasive in-field advanced capability for early detection of hemorrhage and imminent onset of shock. Diagnostic Tests or Criteria; Level III.

Microtubules distinctly contribute to the performance of the healthy and pressure-overloaded RV

Introduction: Microtubules (MT) are a key contributor to cardiomyocyte contractility and mechanics. Recently, our group reported that acute depolymerization of MT reduces viscosity and elasticity and alters anisotropy of healthy and pressure-overloaded right ventricular (RV) tissues. While RV free wall viscosity and elasticity are distinctly upregulated with chronic pressure overload, how organ function is affected by viscoelastic contribution of the MT remains unknown. Our aim was to investigate the role of MT polymerization in RV function from its effect on RV tissue viscoelasticity. We hypothesized that the MT differentially contributes to healthy and pressure-overloaded RV function. Methods: All procedures and methods were approved by Colorado State University IACUC. Pulmonary hypertension (PH) was induced in 6-week-old male rats via 3-week monocrotaline treatment. Healthy age- and sex-matched rats served as control. Pressure-volume (PV) relationships were obtained by RV catheterization before and after intramyocardial injections of 0.3mM colchicine (COL) to acutely depolymerize the MT network and reduce tissue viscoelasticity. Functional impacts were evaluated by monitoring changes in RV end-systolic pressure (ESP), cardiac output (CO), stroke volume (SV), ejection fraction (EF), dP/dt max and min, cardiac effciency (CE), and the end-systolic pressure-volume relation (ESPVR). Results: As expected, monocrotaline treatment induced marked PH and RV contractile dysfunction, indicated by a significant elevation of RV ESP with reduced CO and ESPVR. In the healthy RV, COL treatment led to marked reductions in all functional parameters, indicating that the MT network is critical to maintain RV performance and contractile function in the healthy heart. In the pressure-overloaded RV, COL treatment similarly reduced SV, CO, EF, and dP/dt max and min, but increased CE and ESPVR, indicating that MT depolymerization improved mechanical effciency and contractility. To rule out effects caused by bolus injections alone, we administered a similar quantity of saline and observed no effects on the PV parameters in healthy RV. Discussion: Our study is the first to investigate the acute effect of MT depolymerization on RV function in healthy and diseased states. We found distinct contributions of MT to the contractile function and mechanical effciency of healthy and pressure-overloaded RVs. These findings reveal a critical influence of tissue viscoelasticity on RV physiology and dysfunction, emphasizing the importance of considering myocardial viscoelastic behavior in future studies investigating cardiac remodeling and heart failure pathophysiology. This work is partially supported by the National Science Foundation (NSF) grant 2244994. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

DETERMINANTS OF PHYSIOLOGICAL RESPONSE TO EXERTIONAL HEAT STRESS IN HUMANS

INTRODUCTION AND AIMS Previous field studies of exercise undertaken in hot conditions reported dissociation between heat-related symptoms and body core temperature (Tc) elevation. This prompted us to examine physiological mechanisms underpinning responses to exertional heat exposure in a controlled laboratory experiment. METHODS Thirty-eight apparently healthy participants had body composition (DEXA) and fitness (V̇O2peak) measured in a preliminary visit. Tc, heart rate (HR), exercise intensity (V̇O2) and echocardiographic measures of end-diastolic volume (EDV), stroke volume (SV) and cardiac output (Q̇) were measured at rest and at 30-minute intervals throughout a two-hour walk (5km/h and 2% gradient) in a climate-controlled chamber (40⸰C and 50% relative-humidity). RESULTS Twenty-seven participants completed the experiment (Completers; Com), 7 were stopped due to Tc exceeding 39⸰C (Hyperthermics; Hyp). Four participants did not complete the protocol due to adverse symptoms and were excluded from this analysis. Hyp had significantly greater Tc at 60-minutes (38.6±0.5⸰C vs. 38.0±0.3⸰C; P=&amp;lt;0.001) and 90-minutes (39.0±0.3⸰C vs. 38.3±0.3⸰C; P=&amp;lt;0.001) than Com. Baseline V̇O2peak (ml.kg-1.min-1) did not differ between Hyp and Com (P=0.248). Whilst body weight and lean body mass did not significantly differ between Hyp and Com, visceral adipose tissue (VAT) volume (463.2±194.3cm3 vs. 259.9±284.4cm3 P=0.014) and mass (437.0±183.1g vs. 245.2±268.2g P=0.013) were significantly greater in Hyp vs Com. In Hyp, HR change from baseline was greater at 60-minutes (Δ57±15bpm vs. Δ36±18bpm; P=0.01) and 90-minutes (Δ63±20bpm vs. Δ42±19bpm; P=0.017), whilst change in EDV (Δ-22.7±11.4ml vs. Δ-6.92±11.2ml; P=0.016) and SV (Δ-19.4±6.1ml vs. Δ-0.7±7.5ml; P=&amp;lt;0.001) were significantly reduced in Hyp compared to Com. CONCLUSION During walking in the heat, subjects who became hyperthermic had significantly higher baseline visceral fat mass and early signs of exaggerated haemodynamic burden during exertional heat exposure. This study has implications for the identification of appropriate variables for establishing safe work limits during heat exposure in military and work-related contexts.

Derivation of Stroke Volume from Pulmonary Artery Pressures.

Intermittent cardiac output (CO) studies using thermodilution are considered the gold standard. We have developed a stroke volume (SV) calculator from pulmonary pulse pressure (PP) to allow continuous monitoring of SV and CO from PP. Hemodynamic data on 169 patients following orthotopic heart transplantation were used to compare our calculator-derived SV (and SV index, or SVi) against thermodilution-derived SV on admission into intensive care unit immediately following heart transplantation (T0) and 6h after admission (T6). The calculated SV correlated with thermodilution-derived SV T0 (r = 0.920, p < 0.001, coefficient of 0.539 and the constant of 2.06). The median calculator SV, adjusted for coefficient and constant, was 48.4ml (37.7, 60.7), comparable to the median thermodilution-derived SV 47.9ml (37.5, 61.0), p = 0.737 with acceptable agreement on Bland-Altman plots. The thermodilution-derived SVi was 28.1ml (19.7, 38.7) and adjusted calculator-derived SVi 28.9ml (19.7, 39.9), p = 0.781. At T6, median thermodilution-derived SVi was 27.7ml (19.5, 35.9) compared to the calculator-derived SVi median of 26.1ml (17.7, 37.7), p = 0.203. Changes in PP can be used to track changes in SV using this calculator. Changes in PP may be used to assess response to treatment in the early post-operative period.

Trajectories of functional and structural myocardial parameters in post-COVID-19 syndrome-insights from mid-term follow-up by cardiovascular magnetic resonance.

Myocardial tissue alterations in patients with post-Coronavirus disease 2019 syndrome (PCS) are often subtle and mild. Reports vary in the prevalence of non-ischemic and ischemic injuries as well as the extent of ongoing myocardial inflammation. The exact relevance of these myocardial alterations is not fully understood. This study aimed at describing the trajectories of myocardial alterations in PCS patients by mid-term follow-up with cardiovascular magnetic resonance (CMR). This study entails a retrospective analysis of symptomatic PCS patients referred for follow-up CMR between August 2020 and May 2023 due to mildly affected or reduced left or right ventricular function (LV and RV, respectively) and structural myocardial alterations, e.g., focal and diffuse fibrosis, on baseline scans. Follow-up CMR protocol consisted of cine images and full coverage native T1 and T2 mapping. Baseline and follow-up scans were compared using t-tests or Wilcoxon tests. Post-hoc analysis was carried out in a subgroup based on the change of LV stroke volume (SV) between scans. In total, 43 patients [median age (interquartile range) 46 (37-56) years, 33 women] received follow-ups 347 (167-651) days after initial diagnosis. A decrease in symptoms was recorded on follow-ups (p < 0.03) with 23 patients being asymptomatic at follow-ups [symptomatic at baseline 43/43 (100%) vs. symptomatic at follow-up 21/43 (49%), p < 0.001]. Functional improvement was noted for LV-SV [83.3 (72.7-95.0) vs. 84.0 (77.0-100.3) ml; p = 0.045], global radial [25.3% (23.4%-27.9%) vs. 27.4% (24.4%-33.1%); p < 0.001], and circumferential strains [-16.5% (-17.5% to -15.6%) vs. -17.2% (-19.5% to -16.1%); p < 0.001]. In total, 17 patients had an LV-SV change >10% on follow-up scans (5 with a decrease and 12 with an increase), with LV-SV, RV-SV, and global longitudinal strain being discriminatory variables on baseline scans (p = 0.01, 0.02, and 0.04, respectively). T1- or T2-analysis revealed no changes, remaining within normal limits. Symptomatic load as well as blood pressures decreased on follow-up. CMR did not detect significant changes in tissue parameters; however, volumetric, specifically LV-SV, and deformation indexes improved during mid-term follow-up.

Positive effects of low-dose S-ketamine on preventing myocardial injury after thoracoscopic lobectomy in patients aged 70 to 85

ObjectiveTo investigate the effects of low-dose S-ketamine on marker of myocardial injury (BNP, hs-cTnT and HFABP) after thoracoscopic lobectomy in patients aged 70 to 85.MethodsOne hundred patients (four cases excluded) aged 70–85 years, with body mass index 18–24 kg·m−2 and American Society of Anesthesiologists physical status II–III, scheduled for elective lobectomy from April 2022 to April 2023, were selected. The patients were divided into two groups by a random number table method, namely, the low-dose S-ketamine combined with GDFT group (group S) and the control group (group C), with 48 cases in each group. In group S, a low dose of S-ketamine (0.2 mg/kg) was given 1 min before intubation, and the maintenance dose was 0.12 mg·kg−1·h−1. Fluid therapy, guided by cardiac index (CI), changes in stroke volume (△SV), and other dynamic indicators, was used for rehydration during the operation. Group C was given the same amount of normal saline (0.2 mg/kg) 1 min before intubation, and the same rehydration therapy was adopted during the operation. The mean arterial pressure (MAP) and heart rate (HR) of the two groups were observed and recorded immediately after entering the operating room (T0), immediately after intubation (T1), immediately after the beginning of one-lung ventilation (OLV) (T2), immediately after the beginning of surgery (T3), immediately after the end of OLV (T4), and at the end of surgery (T5). The intraoperative fluid intake and output and the use of vasoactive drugs were recorded. The plasma levels of heart-type fatty acid–binding protein (HFABP), high-sensitivity troponin T (hs-cTnT), brain natriuretic peptide (BNP), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) were recorded 24 h before operation and 24 and 48 h after operation. Visual analogue scale (VAS) pain scores at rest were recorded at 2 (V1), 6 (V2), 12 (V3), 24 (V4), and 48 h (V5) after operation, and the occurrence of myocardial ischemia during hospitalization was noted.ResultsCompared with group C, MAP was significantly higher at T1–T5 in group S (P < 0.05), and the plasma concentrations of IL-6, IL-8, TNF-α, BNP, hs-cTnT, and HFABP were significantly lower at 24 and 48 h after operation (P < 0.05). The VAS pain scores at 2, 6, 12, 24, and 48 h after operation, the number of effective patient-controlled intravenous analgesia (PCIA) compressions, and the total number of PCIA compressions within 48 h after operation were significantly decreased (P < 0.05). Compared with group C, The hospitalization days, and the incidence of postoperative myocardial ischemia in group S were lower (P < 0.05). There were no significant intergroup differences in urine volume, extubation time, the incidence of postoperative atrial fibrillation, bleeding volume, colloid infusion volume, total fluid infusion volume, and the incidence of rescue analgesia.ConclusionsLow-dose S-ketamine can reduce the levels of hs-cTnT, HFABP, and BNP in older patients after pulmonary lobectomy, which has a positive effect on preventing myocardial injury.Trial registrationThis study was registered on CHICTR (registration No. ChiCTR2300074475). Date of registration: 08/08/2023.

Exploring congestion endotypes and their distinct clinical outcomes among ICU patients: A post-hoc analysis

BackgroundIn the intensive care unit (ICU) patients, fluid overload and congestion are associated with worse outcomes. Because of the heterogeneity of ICU patients, we hypothesized that there may exist different endotypes of congestion. The aim of this study was to identify endotypes of congestion and their association with outcomes. MethodsWe conducted an unsupervised hierarchical clustering analysis on 145 patients admitted to ICU to identify endotypes. We measured several parameters related to clinical context, volume status, filling pressure, and venous congestion. These parameters included NT-proBNP, central venous pressure (CVP), the mitral E/e' ratio, the systolic/diastolic ratio of hepatic veins' flow velocity, the mean diameter of the inferior vena cava (IVC) and its variations, stroke volume changes following passive leg raising, the portal vein pulsatility index, and the venous renal impedance index. ResultsThree distinct endotypes were identified: (1) “hemodynamic congestion” endotype (n = 75) with moderate alterations of ventricular function, increased CVP and left filling pressure values, and moderate fluid overload; (2) “volume overload congestion” endotype (n = 50); with normal cardiac function and filling pressure despite high positive fluid balance (fluid overload); (3) “systemic congestion” endotype (n = 20) with severe alterations of left and right ventricular functions, increased CVP and left ventricular filling pressure values. These endotypes vary significantly in ICU admission reasons, acute kidney injury rates, mortality, and length of ICU/hospital stay. ConclusionsOur analysis revealed three unique congestion endotypes in ICU patients, each with distinct pathophysiological features and outcomes. These endotypes are identifiable through key ultrasonographic characteristics at the bedside. Clinical trial govNCT04680728.

Prediction of preload dependency using phenylephrine-induced peripheral perfusion index during general anaesthesia: a prospective observational study

BackgroundTracking preload dependency non-invasively to maintain adequate tissue perfusion in the perioperative period can be challenging.The effect of phenylephrine on stroke volume is dependent upon preload. Changes in stroke volume induced by phenylephrine administration can be used to predict preload dependency. The change in the peripheral perfusion index derived from photoplethysmography signals reportedly corresponds with changes in stroke volume in situations such as body position changes in the operating room. Thus, the peripheral perfusion index can be used as a non-invasive potential alternative to stroke volume to predict preload dependency. Herein, we aimed to determine whether changes in perfusion index induced by the administration of phenylephrine could be used to predict preload dependency.MethodsWe conducted a prospective single-centre observational study. The haemodynamic parameters and perfusion index were recorded before and 1 and 2 min after administering 0.1 mg of phenylephrine during post-induction hypotension in patients scheduled to undergo surgery. Preload dependency was defined as a stroke volume variation of ≥ 12% before phenylephrine administration at a mean arterial pressure of < 65 mmHg. Patients were divided into four groups according to total peripheral resistance and preload dependency.ResultsForty-two patients were included in this study. The stroke volume in patients with preload dependency (n = 23) increased after phenylephrine administration. However, phenylephrine administration did not impact the stroke volume in patients without preload dependency (n = 19). The perfusion index decreased regardless of preload dependency. The changes in the perfusion index after phenylephrine administration exhibited low accuracy for predicting preload dependency. Based on subgroup analysis, patients with high total peripheral resistance tended to exhibit increased stroke volume following phenylephrine administration, which was particularly prominent in patients with high total peripheral resistance and preload dependency.ConclusionThe findings of the current study revealed that changes in the perfusion index induced by administering 0.1 mg of phenylephrine could not predict preload dependency. This may be attributed to the different phenylephrine-induced stroke volume patterns observed in patients according to the degree of total peripheral resistance and preload dependency.Trial registrationUniversity Hospital Medical Information Network (UMIN000049994 on 9/01/2023).

Cardiac dysfunction during exercise in young adults with bronchopulmonary dysplasia.

Worldwide, 1-2% of children are born premature and at risk for developing bronchopulmonary dysplasia (BPD). Preterm-born adults are at risk for early cardiovascular disease. The role of BPD is unclear. This study aims to examine cardiorespiratory function during submaximal exercise in young adult survivors of extreme prematurity, with or without BPD. 40 preterm-born young adults, 20 with BPD (median gestational age 27 weeks, interquartile range (IQR) 26-28 weeks) and 20 without BPD (median gestational age 28 weeks, IQR 27-29 weeks) were prospectively compared to age-matched at term-born adults (median gestational age 39 weeks, IQR 38-40 weeks). Participants underwent exercise testing and cardiovascular magnetic resonance with submaximal exercise. Resting heart rate in BPD subjects was higher than in at term-born subjects (69±10 mL versus 61±7 mL, p=0.01). Peak oxygen uptake during maximal cardiopulmonary exercise testing was decreased in BPD subjects (91±18% versus 106±17% of predicted, p=0.01). In BPD subjects, cardiac stroke volume change with exercise was impaired compared to at term-born subjects (11±13% versus 25±10%; p<0.001). With exercise, left ventricular end-diastolic volume decreased more in preterm-born subjects with versus without BPD (-10±8% versus -3±8%; p=0.01) and compared to at term-born subjects (0±5%; p<0.001). Exploratory data analysis revealed that exercise stroke volume and end-diastolic volume change were inversely correlated with oxygen dependency in those born prematurely. In preterm-born young adults, particularly those with BPD, resting cardiac function, exercise performance and cardiac response to exercise is impaired compared to controls. Exercise cardiovascular magnetic resonance may reveal an important predisposition for heart disease later in life.

Comparison of noninvasive cardiac output and stroke volume measurements using electrical impedance tomography with invasive methods in a swine model.

Pulmonary artery catheterization (PAC) has been used as a clinical standard for cardiac output (CO) measurements on humans. On animals, however, an ultrasonic flow sensor (UFS) placed around the ascending aorta or pulmonary artery can measure CO and stroke volume (SV) more accurately. The objective of this paper is to compare CO and SV measurements using a noninvasive electrical impedance tomography (EIT) device and three invasive devices using UFS, PAC-CCO (continuous CO) and arterial pressure-based CO (APCO). Thirty-two pigs were anesthetized and mechanically ventilated. A UFS was placed around the pulmonary artery through thoracotomy in 11 of them, while the EIT, PAC-CCO and APCO devices were used on all of them. Afterload and contractility were changed pharmacologically, while preload was changed through bleeding and injection of fluid or blood. Twenty-three pigs completed the experiment. Among 23, the UFS was used on 7 pigs around the pulmonary artery. The percentage error (PE) between COUFS and COEIT was 26.1%, and the 10-min concordance was 92.5%. Between SVUFS and SVEIT, the PE was 24.8%, and the 10-min concordance was 94.2%. On analyzing the data from all 23 pigs, the PE between time-delay-adjusted COPAC-CCO and COEIT was 34.6%, and the 10-min concordance was 81.1%. Our results suggest that the performance of the EIT device in measuring dynamic changes of CO and SV on mechanically-ventilated pigs under different cardiac preload, afterload and contractility conditions is at least comparable to that of the PAC-CCO device. Clinical studies are needed to evaluate the utility of the EIT device as a noninvasive hemodynamic monitoring tool.

Assessing fluid responsiveness with ultrasound in the neonatal intensive care setting: the mini-fluid challenge.

The mini-fluid challenge (MFC) can guide individualised fluid therapy and prevent fluid overload and associated morbidity in adult intensive care patients. This ultrasound test is based on the Frank-Starling principles to assess dynamic fluid responsiveness, but limited MFC data exists for newborns.This brief report describes the feasibility of the MFC in 12 preterm infants with late onset sepsis and 5 newborns with other pathophysiology. Apical views were used to determine the changes in left ventricular stroke volume before and after a 3ml/kg fluid bolus was given over 5min. Four out of the 17 infants were fluid responsive, defined as a post-bolus increase in stroke volume of 15% or more. Conclusion: The MFC was feasible and followed the physiological principles of stroke volume and extravascular lung water changes and 24% were fluid responsive. The MFC could enable future studies to examine whether adding fluid responsiveness to guide fluid therapy in newborns can reduce the risk of fluid overload. What is Known: • Fluid overload is associated with morbidity and mortality. • The mini-fluid challenge (MFC) provides a personalised approach to fluid therapy. What is New: • The MFC is feasible in newborns. • The MFC followed the physiological principles of stroke volume and extravascular lung water changes.

Improving the precision of shock resuscitation by predicting fluid responsiveness with machine learning and arterial blood pressure waveform data

Fluid bolus therapy (FBT) is fundamental to the management of circulatory shock in critical care but balancing the benefits and toxicities of FBT has proven challenging in individual patients. Improved predictors of the hemodynamic response to a fluid bolus, commonly referred to as a fluid challenge, are needed to limit non-beneficial fluid administration and to enable automated clinical decision support and patient-specific precision critical care management. In this study we retrospectively analyzed data from 394 fluid boluses from 58 pigs subjected to either hemorrhagic or distributive shock. All animals had continuous blood pressure and cardiac output monitored throughout the study. Using this data, we developed a machine learning (ML) model to predict the hemodynamic response to a fluid challenge using only arterial blood pressure waveform data as the input. A Random Forest binary classifier referred to as the ML fluid responsiveness algorithm (MLFRA) was trained to detect fluid responsiveness (FR), defined as a ≥ 15% change in cardiac stroke volume after a fluid challenge. We then compared its performance to pulse pressure variation, a commonly used metric of FR. Model performance was assessed using the area under the receiver operating characteristic curve (AUROC), confusion matrix metrics, and calibration curves plotting predicted probabilities against observed outcomes. Across multiple train/test splits and feature selection methods designed to assess performance in the setting of small sample size conditions typical of large animal experiments, the MLFRA achieved an average AUROC, recall (sensitivity), specificity, and precision of 0.82, 0.86, 0.62. and 0.76, respectively. In the same datasets, pulse pressure variation had an AUROC, recall, specificity, and precision of 0.73, 0.91, 0.49, and 0.71, respectively. The MLFRA was generally well-calibrated across its range of predicted probabilities and appeared to perform equally well across physiologic conditions. These results suggest that ML, using only inputs from arterial blood pressure monitoring, may substantially improve the accuracy of predicting FR compared to the use of pulse pressure variation. If generalizable, these methods may enable more effective, automated precision management of critically ill patients with circulatory shock.

The left ventricular outflow tract and carotid artery velocity time integrals

The left ventricular outflow tract velocity time integral (LVOT VTI) is commonly used in the intensive care unit as a measure of stroke volume (SV) and how the SV changes in response to an intervention; therefore, the LVOT VTI is used to guide intravenous fluid management. Various peripheral Doppler surrogates are proposed to infer the LVOT VTI (e.g., measures from the common carotid artery). A recently-described, novel method of insonation has an excellent ability to detect change in the LVOT VTI. This approach raises important facets of Doppler flow and insonation error, as well as the general principles at play when using a peripheral artery to infer changes from the left ventricle. Relating the VTI of a peripheral artery to the LVOT VTI was recently described mathematically and may help clinicians think about the Doppler relationship between central and peripheral flow.