Aortic Velocity Time Integral Research Articles

Fluid responsiveness in acute respiratory distress syndrome patients: a post hoc analysis of the HEMOPRED study.

Optimal fluid management in patients with acute respiratory distress syndrome (ARDS) is challenging due to risks associated with both circulatory failure and fluid overload. The performance of dynamic indices to predict fluid responsiveness (FR) in ARDS patients is uncertain. This post hoc analysis of the HEMOPRED study compared the performance of dynamic indices in mechanically ventilated patients with shock, with and without ARDS, to predict FR, defined as an increase in aortic velocity time integral (VTI) > 10% after passive leg raising (PLR). Among 540 patients, 117 (22%) had ARDS and were ventilated with a median tidal volume of 7.6 mL/kg [6.9-8.4] and a median positive end-expiratory pressure of 7 cmH2O [5-9]. FR was observed in 45 ARDS patients (39% vs 44% in non-ARDS patients, p = 0.384). Reliability of dynamic indices to predict FR remained consistent in ARDS patients, though with different thresholds. Collapsibility index of the superior vena cava (ΔSVC) showed the best predictive performance in both ARDS (area under the curve [AUC] = 0.763 [0.659-0.868]) and non-ARDS (AUC = 0.750 [0.698-0.802]) patients. A right to left ventricle end-diastolic area ratio > 0.8 or paradoxical septal motion were strongly linked to the absence of FR (> 80% specificity). FR was not associated with intensive care unit (ICU) mortality (47% vs. 46%, p = 1). However, hypovolemia, defined as an aortic VTI increase > 32% during PLR (median increase in patients with a partial SVC collapse) was independently associated with ICU mortality (odds ratio [OR] = 1.355 [1.077-1.705], p = 0.011), as well as pulse pressure variation (OR = 1.014 [1.001-1.026], p = 0.034). Performance of dynamic indices to predict FR appears preserved in ARDS patients, albeit with distinct thresholds. Hypovolemia, indicated by a > 32% increase in aortic VTI during PLR, rather than FR, was associated with ICU mortality in this population.

Assessment of the correlation between Doppler derived dP/dt and aortic velocity-time integral during cardiac resynchronization therapy optimization.

Suboptimal response to cardiac resynchronization therapy (CRT) may be improved by optimization of device parameters using echocardiography. For this purpose, the aortic velocity-time integral (aVTI) has been used as a target metric to define optimal velocity timings for each ventricle. dP/dt is a parameter used for the assessment of myocardial contractility. In this study, we aimed to evaluate the effectiveness of Doppler-derived dP/dt in optimization by assessing the possible correlation between aVTI and dP/dt. Patients with CRT admitted for routine follow-up were included in the study. Aortic VTI and dP/dt measurements were recorded in four different standard pacing configurations during reprogramming. A total of 45 patients were included in the final analysis. No correlation was found between the aVTI and the delta dP/dt value in the two configurations where the change in dP/dt was maximum (p = 0.894). In the two configurations where the change in aVTI was maximum, there was also no correlation between the delta dP/dt and the delta aVTI (p = 0.715). When patients were dichotomized according to the median value of dP/dt, there were no differences in aVTI, NYHA classes, LVEF, and mitral regurgitation (MR) severity (p = 0.4; p = 0.5; p = 0.7; p = 0.3; respectively). The change in both dP/dt and aVTI was statistically significant when switching from RV-only to QRS width-targeted configuration (p = 0.001; p = 0.041; respectively). In conclusion, aVTI recorded at different pacing configurations did not correlate with dP/dt during interventricular optimization. However, both parameters consistently showed a positive effect of biventricular pacing on contractile synchronization and stroke volume.

Association between echocardiographic indexes and urinary Neutrophil Gelatinase-Associated Lipocalin (uNGAL) in dogs with myxomatous mitral valve disease

Neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker of tubular damage, and its elevation has been described in human and canine cardiorenal syndrome.The aim was to evaluate the association between echocardiographic indexes and urine NGAL (uNGAL) and uNGAL normalized to urine creatinine (uNGALC) in dogs with MMVD.This is a multicentric prospective cross-sectional study. A total of 77 dogs with MMVD at different ACVIM stages were included. All dogs underwent echocardiography, serum chemistry, and urinalysis. Echocardiographic data analyzed were shortening fraction (SF), left ventricular diastolic (LVIDDn) and systolic (LVIDSn) diameters normalized for body weight, left atrium to aortic root ratio (LA/Ao), maximal (LAVMax) and minimal (LAVMin) left atrial volumes, LA stroke volume (LASV), early diastolic mitral peak velocity (EVmax), EVmax to tissue Doppler E' wave (E/E'), aortic (VTIAo) and mitralic (VTIMit) velocity time integrals and their ratio (VTIMit/VTIAo), and tricuspid regurgitation velocity (TRVmax).In the univariate analysis LASV, TRVmax, LAVMax, LVIDDn, and VTIMit/VTIAo were independent predictors of increased uNGAL and uNGALC; however, only LASV [(OR: 1.96, 95% CI: 1.16 to 3.31) P = 0.01 for NGAL, and (OR: 2.79, 95% CI: 1.50 to 5.17) P < 0.001 for NGALC] and TRVmax [(OR: 1.73, 95% CI: 1.20–2.51) P = 0.002 for NGAL, and (OR: 1.50, 95% CI: 10.07–2.10) P = 0.015 for NGALC] remained statistically significant in the multivariable analysis.Based on our results, LASV and TRVmax are associated with increased uNGAL and uNGALC. These parameters might detect dogs with MMVD at higher risk of developing kidney damage.

Assessment of cardiac load-responsiveness in veno-arterial extracorporeal life support: A case series.

Well-timed explant of veno-arterial extracorporeal life support (V-A ECLS) depends on adequate assessment of cardiac recovery. Often, evaluation of cardiac recovery consists of reducing support flow while visualizing cardiac response using transoesophageal echocardiography (TEE). This method, however, is time consuming and based on subjective findings. The dynamic filling index (DFI) may aid in the quantitative assessment of cardiac load-responsiveness. The dynamic filling index is based on the relationship of support flow and pump speed, which varies with varying hemodynamic conditions. This case series intends to investigate whether the DFI may support TEE in facilitating the assessment of cardiac load-responsiveness. Measurements for DFI-determination were performed in seven patients while simultaneously assessing ventricular function by measuring the aortic velocity time integral (VTI) using TEE. Measurements consisted of multiple consecutive transient speed manipulations (∼100r/min) during weaning trials, both at full support and during cardiac reloading at reduced support. The VTI increased between full and reduced support in six weaning trials. In five of these trials DFI decreased or remained equal, and in one case DFI increased. Of the three trials in which VTI decreased between full and reduced support, DFI increased in two cases and decreased in one case. Changes in DFI, however, are mostly smaller than the detection threshold of 0.4mL/rotation. Even though current level of accuracy of the parameter requires further investigation to increase reliability and possibly predictability, DFI seems likely to be a potential parameter in supporting TEE for the assessment of cardiac load-responsiveness.

RESPIRATORY VARIABILITY OF VALVULAR PEAK SYSTOLIC VELOCITY AS A NEW INDICATOR OF FLUID RESPONSIVENESS IN PATIENTS WITH SEPTIC SHOCK.

Objective: The aim of this study was to evaluate the reliability and feasibility of pulse Doppler measurements of peak velocity respiratory variability of mitral and tricuspid valve rings during systole as new dynamic indicators of fluid responsiveness in patients with septic shock. Methods: Transthoracic echocardiography (TTE) was performed to measure the respiratory variability of aortic velocity-time integral (∆VTI), respiratory variability of tricuspid annulus systolic peak velocity (∆RVS), respiratory variability of mitral annulus systolic peak velocity (∆LVS), and other related indicators. Fluid responsiveness was defined as a 10% increase in cardiac output after fluid expansion, assessed by TTE. Results: A total of 33 patients with septic shock were enrolled in this study. First, there was no significant difference in the population characteristics between the fluid responsiveness positive group (n = 17) and the fluid responsiveness negative group (n = 16) ( P > 0.05). Second, Pearson correlation test showed that ∆RVS, ∆LVS, and TAPSE with the relative increase in cardiac output after fluid expansion ( R = 0.55, P = 0.001; R = 0.40, P = 0.02; R = 0.36, P = 0.041). Third, multiple logistic regression analysis demonstrated that ∆RVS, ∆LVS, and TAPSE were significantly correlated with fluid responsiveness in patients with septic shock. Fourth, receiver operating characteristic (ROC) curve analysis revealed that ∆VTI, ∆LVS, ∆RVS, and TAPSE had good predictive ability for fluid responsiveness in patients with septic shock. The area under the curve (AUC) of ∆VTI, ∆LVS, ∆RVS, and TAPSE for predicting fluid responsiveness was 0.952, 0.802, 0.822, and 0.713, respectively. The sensitivity (Se) values were 1.00, 0.73, 0.81, and 0.83, whereas the specificity (Sp) values were 0.84, 0.91, 0.76, and 0.67, respectively. The optimal thresholds were 0.128, 0.129, 0.130, and 13.9 mm, respectively. Conclusion: Tissue Doppler ultrasound evaluation of respiratory variability of mitral and tricuspid annular peak systolic velocity could be a feasible and reliable method for the simple assessment of fluid responsiveness in patients with septic shock.

Modification of a Transvalvular Microaxial Flow Pump for Instantaneous Determination of Native Cardiac Output and Volume

The current Impella CP pump used for mechanical circulatory support (MCS) in patients with cardiogenic shock (CS) cannot assess native cardiac output (CO) and left ventricular (LV) volumes. This data is valuable in facilitating device management and weaning. Admittance technology allows for accurate assessment of cardiac chamber volumes. This study tested the ability to engineer admittance electrodes onto an existing Impella CP pump to assess total and native CO in an instantaneous manner, as well as LV chamber volumes. Impella CP pumps were fitted with four admittance electrodes and placed in the LV of adult swine (n=9) subjected to three different hemodynamic conditions including Impella CP speed adjustments, administration of escalating doses of dobutamine, and microsphere injections into the left main artery to result in cardiac injury. CO by admittance electrodes was calculated from LV volumes and heart rate. In addition, CO was calculated in each instance via thermodilution, continuous CO (CCO) measurement, Fick's principle and aortic velocity-time integral (VTI) by echocardiography. Modified Impella CP pumps were placed in swine LV successfully. CO as determined by admittance electrodes was similar by trend with other methods of CO assessment, corrected for pump speed to calculate native CO, and calculated LV chamber volumes trended as expected in each experimental protocol. We report for the first time that an Impella CP pump can be fitted with admittance electrodes and used to determine total and native CO in various hemodynamic situations. Transvalvular mechanical circulatory support (MCS) devices such as the Impella CP do not have the ability to provide real-time information on native cardiac output (CO) and left ventricular (LV) volumes. This information is critical in device management and weaning in patients with cardiogenic shock (CS). We demonstrate for the first time, an Impella CP pump coupled with admittance electrodes are able to determine native CO, and left ventricle (LV) chamber volumes in multiple different hemodynamic situations such as Impella pump speed adjustments, escalating dobutamine administration, and cardiac injury from microsphere injection.

Left ventricular systolic function in subjects conceived through assisted reproductive technologies.

Over the past decades, assisted reproductive technologies (ART) have gained remarkable influence in the treatment of infertility and account for more than 2 % of births in European countries nowadays. Accumulating evidence suggests ART to cause cardiovascular alterations, including left ventricular (LV) dysfunctions, within its offspring. The aim of this study was to assess LV systolic function in subjects conceived through ART in comparison to spontaneously conceived peers. For the assessment of LV morphology and LV function, M-Mode echocardiography, pulsed wave Doppler and two-dimensional speckle tracking echocardiography (2DSTE) were applied. LV ejection fraction (EF) and fractional shortening (FS) were assessed in M-Mode and calculated by Teichholz formula. EF was additionally assessed semiautomatically through 2DSTE. In total, 64 ART subjects and 83 spontaneously conceived controls with no significant differences in age (12.52 ± 5.64 years vs. 13.20 ± 5.95 years, p = 0.486) and sex were included in the analysis. In the ART cohort, significantly lower values were observed for M-Mode assessed EF (63.63 ± 5.17 % vs. 65.35 ± 5.10 %, p = 0.046) and FS (34.26 ± 3.87 % vs. 35.60 ± 3.84 %, p = 0.038). However, after the adjustment for birth weight percentile and gestational age, M-Mode assessed EF and FS displayed no significant differences between both groups. LV morphology and remaining systolic function parameters, such as mitral annular plane systolic excursion, aortic velocity time integral, global peak longitudinal strain and 2DSTE measured EF, were comparable between both groups. This study suggests a lower LV systolic function in ART subjects, visualized by significantly lower values for M-Mode assessed EF and FS, compared to spontaneously conceived peers. The clinical relevance of these findings has to be investigated as the above-mentioned parameters were in normal reference range. In addition, LV systolic function parameters evaluated by other echocardiographic imaging modalities were comparable between both groups. Therefore, further studies will be required to evaluate the influence of ART on LV systolic function and cardiovascular morbidity in the future.

The assessment of fetal cardiac output in maternal hypothyroidism under levothyroxine treatment.

In this study, we investigated whether maternal hypothyroidism has a role in the cardiac output (CO) of the fetus or not. Pregnant women between 33 and 37 gestational weeks known to have hypothyroidism and using levothyroxine were accepted as the case group. Gestational age-matched healthy euthyroid pregnant women constituted the control group. Fetal echocardiography was performed. Diameters and the velocity waveform of the pulmonary artery (PA) and aortic valves were measured. Velocity time integral (VTI) was also measured from the ventricular outflow tract. CO was calculated using VTI × π (Aortic Valve or Pulmonary Valve diameter/2) 2 × heart rate formula. The aortic and PA annulus were measured larger in the control group. (p=.003, p=.005, respectively). Furthermore, the right and left CO of the case group were lower than the control group. Whereas the mean combined CO (ml/min) of the case group was 674.8±146.2, it was 827.8±167.9 in the control group (p&lt;.001). Additionally, a negative correlation was observed between thyroid-stimulating hormone and aortic VTI (r:-.480; p:.006). The findings of our study suggest that the CO of the fetus may be affected by maternal hypothyroidism.

Evaluation of diagnostic criteria in grey parrots (Psittacus erithacus) with suspected atherosclerosis.

Atherosclerosis is a common disease in older psittacines living in captivity with inadequate housing conditions. However, diagnosis in the living bird remains difficult and the disease is often only recognized during post mortem examination. In this context, we aimed at investigating the diagnostic value of currently reported methods in African grey parrots (Psittacus erithacus). 7 clinically healthy African grey parrots and 32 African grey parrots with suspected atherosclerosis were evaluated in this study. An overall scoring system was implemented based on clinical signs, measurement of blood cholesterol and triglyceride levels, a radiographic exam, and an echocardiogram in B-mode. Furthermore, measurements of the blood flow velocity in the aortic root, heart rate and velocity time integral were performed using the spectral Doppler ultrasonographic function. Measurements of the blood flow velocity in the aortic root showed highly significant differences between the clinically healthy group and a subset of the patient group. Significant differences between the groups also were evident concerning the results of the overall scoring and of the initial examinations. The results support that combining spectral Doppler ultrasonographic examination with other diagnostic options may be used to substantiate suspected atherosclerosis and provide additional information regarding the cardiovascular status of the patient. The presented findings indicate that employing the described diagnostic methods allows for an intra vitam diagnosis of atherosclerosis and therefore an earlier initiation of treatment.

Effect Evaluation of Cardiac Resynchronization Therapy in Elderly Patients with Heart Failure by Ultrasound Image under QuickOpt Algorithm.

This research was aimed at analyzing the application value of echocardiography and QuickOpt algorithm in optimizing parameters of cardiac resynchronization therapy (CRT) in elderly patients with heart failure. 50 elderly patients who were diagnosed with chronic heart failure and underwent CRT were chosen as the research objects. According to the different optimization methods, the patients were divided into the echocardiography group and QuickOpt algorithm group, 25 cases in each group. The general data, optimized intervals, corresponding maximum aortic velocity time integrals (aVTIs), cardiac ultrasound indicators, and ventricular arrhythmia episodes of the patients in the two groups were analyzed. The results showed that there was no significant difference in the optimized sensed atrioventricular (SAV), paced atrioventricular (PAV), and ventricle to ventricle (VV) intervals and the corresponding aVTIs obtained by echocardiography and QuickOpt (P > 0.05). The consistency analysis revealed that the aVTIs in the SAV, PAV, and VV intervals presented a good consistency (P < 0.01), which were obtained by the echocardiography and QuickOpt functional optimization; the concordance correlation coefficient (CCC) in them was 96.16%, 98.03%, and 95.48%, respectively. The left ventricular ejection fraction (LVEF) showed an increasing trend over time in both groups, while the left ventricular end systolic volume (LVESV), left ventricular end diastolic volume (LVEDV), and morphological right ventricle (MRV) showed the downward trends over time, and the differences between two groups were not significant (P > 0.05). For the premature ventricular contraction (PVC) of ventricular arrhythmia episodes, there was no significant difference between the two groups in log (PVCs) and log (PVC runs) (P > 0.05). It was also found that both echocardiography and QuickOpt algorithm could improve the cardiac function of patients with heart failure significantly and reduce ventricular arrhythmia episodes and ventricular remodeling via optimized CRT; there was no difference in the improvement effect of the two optimization methods. However, echocardiography was inferior to QuickOpt algorithm in terms of time-consuming optimization in the intervals. This provided a reference for the clinical diagnosis and treatment of elderly patients with heart failure.

Intra-aortic balloon pump impacts the regional haemodynamics of patients with cardiogenic shock treated with femoro-femoral veno-arterial extracorporeal membrane oxygenation.

AimsTo investigate the impact of intra‐aortic balloon pump (IABP) on the regional haemodynamics of patients with severe cardiogenic shock undergoing femoro‐femoral veno‐arterial extracorporeal membrane oxygenation (VA‐ECMO).Methods and resultsFrom July 2017 to April 2018, a total of 39 adult patients with cardiogenic shock receiving both IABP and ECMO for circulatory support were enrolled consecutively in a university‐affiliated cardiac surgery intensive care unit. The blood flow rates (BFRs) of the bilateral femoral artery (IABP side: iFA, ECMO side: eFA) and carotid artery (left: LCA, right: RCA) and the velocity time integral (VTI) of aortic root were assessed by ultrasonography and compared when IABP was on and off. Seventeen of 39 (43.6%) patients survived to discharge, and 29 (74.4%) survived on ECMO. A total of 172 pairs of data (IABP on and off) were collected in this study, measured on the median of 2.0 (1.0, 4.5) days after patients received VA‐ECMO. The BFR on both sides of FA (iFA: 176.4 ± 104.5 vs. 152.2 ± 139.8 mL/min, P < 0.01; eFA: 299.3 ± 279.9 vs. 242.4 ± 258.8 mL/min, P < 0.01) and the aortic VTI (10.1 ± 4.4 vs. 8.5 ± 4.4 cm, P < 0.01) decreased significantly when turning the IABP off, while the BFR on both sides of CA remained unchanged (LCA: 555.7 ± 326.9 vs. 578.6 ± 328.0 mL/min, P = 0.27; RCA: 550.0 ± 331.1 vs. 533.0 ± 303.5 mL/min, P = 0.30). The LCA BFR dramatically increased after turning the IABP off (296.8 ± 129.7 vs. 401.4 ± 278.1 mL/min, P = 0.02) in patients with cardiac stunning (defined as pulse pressure ≤ 5 mmHg). However, there was no significant difference in LCA BFR between IABP‐On and IABD‐Off (359.6 ± 105.4 mL/min vs. 389.6 ± 139.3 mL/min, P = 0.31) in patients with cardiac stunning receiving a higher ECMO blood flow (> 3.5 L/min).ConclusionsConcomitant IABP used in patients undergoing femoro‐femoral VA‐ECMO was associated with increased aortic VTI and BFR in bilateral FA. The change in CA BFR depended on cardiac function. A decreased LCA BFR was observed in patients with cardiac stunning when IABP was turned on, which might be compensated by a higher ECMO blood flow. Further study is needed to confirm the relationship between BFR and extremities and neurological complications.

Carotid vs. aortic velocity time integral and peak velocity to predict fluid responsiveness in mechanically ventilated patients. A comparative study.

The carotid artery velocity-time integral (<inf>C</inf>VTI) and the carotid Doppler peak velocity (cDPV), as well as measures of their variation induced by the respiratory cycle, have been proposed as fast and easy to obtain ultrasound measures for assessing fluid responsiveness in intensive care unit patients. To investigate this possibility, we conducted a prospective observational study in hemodynamically unstable patients under mechanical ventilation. From May 1 to December 31, 2019, we conducted a prospective observational study involving 50 hemodynamically unstable patients under mechanical ventilation. We obtained a total of 800 Doppler ultrasound measurements from the left common carotid artery and at the level of the aortic annulus in the apical five-chamber view. The two measurements were performed before and after a 7 mL/kg fluid challenge and within the first hour of the onset of hemodynamic instability. The maximum Doppler peak velocity, the minimum Doppler peak velocity, and the maximum and minimum VTI at both the aortic and carotid level were acquired. Twenty-eight (56%) patients showed a ≥15% increase in <inf>Ao</inf>VTI after the fluid challenge, and were therefore identified as "fluid responders". All Doppler measurements were always significantly greater (P<0.0001) in fluid responders in relation to both carotid and aortic parameters. Good agreement between the above-mentioned measurements was found: Cohen's kappa coefficient between the carotid and aortic ΔDPV was 0.76 (95% CI 0.58-0.94); and between the Carotid and Aortic ΔVTI it was 0.84 (95% CI 0.68-0.99). <inf>C</inf>DPV was found to predict fluid responsiveness in unstable mechanically ventilated patients.

Impact of doppler velocity index after transcatheter aortic valve replacement using Sapien-3 valve – a single centre experience

Abstract Background Little is known about the hemodynamic performance of Edwards Sapien-3 (S3) valve after Transcatheter Aortic Valve Replacement (TAVR). Doppler velocity index (DVI) is a better indicator of prosthetic valve function as it is independent of valve size and flow, unlike mean gradient and peak velocity which are flow-dependent. Methods In this study, we compare outcomes based on differences in DVI among a consecutive series of patients who underwent S3 TAVR between April 2015 and December 2018. Our institutional review board approved the study and informed consents were obtained from the subjects. Results Among 921 patients who had follow-up echocardiograms within 30 days after TAVR, 60.8% had DVI ≤0.5, while 39.2% had DVI &amp;gt;0.5. The median 30-day DVI was 0.47 with a standard deviation of 0.11 and mean 0.49 and interquartile range 0.41–0.55. The baseline clinical and procedural characteristics were similar between both groups with the exception of less post-dilation (36.8% vs. 47.4%; p=0.001) and greater implantation depth (2.59±1.99 vs. 2.31±1.9mm; p=0.031) with DVI ≤0.5. The rates of aortic valve calcification, pre dilation, pre-TAVR aortic regurgitation (AR) were similar. At baseline, there were no differences between both groups in mean or peak gradients or aortic velocity time integral (VTI). At 1 year, mean gradients were higher with DVI ≤0.5 (12.7±5.6 vs. 11.1±4.6 mmHg; p=0.001). DVI ≤0.5 was associated with higher peak gradients (24.2±10.2 vs. 21.4±8.7 mmHg; p=0.002), and aortic VTI (51.4±13.5 vs. 46.8±12.2 cm; p&amp;lt;0.001) at 1 year, especially with the 26mm and 29mm prostheses. Compared with DVI&amp;gt;0.5 group, patients in DVI&amp;lt;0.5 group had lower baseline left ventricular ejection fraction (LVEF) (54.5±12.2% vs. 58.9±11.2%; p&amp;lt;0.001), higher left ventricular end-diastolic volume index (LVEDVi) (54.3±20.9 vs. 49.4±17.4 ml/m2; p=0.001), higher LV end-systolic volume index (LVESVi) (25.2±16.5 vs. 21.3±12.7 ml/m2; p=0.001), and similar LV mass index (110.7±31.9 vs. 106.9±32.7 g/m2; p=0.134). 1-year mortality rates among patients who had DVI ≤0.5 compared to DVI &amp;gt;0.5 were lower (6.6% vs. 10.6%; log-rank p=0.033), however no difference was noted at both 2 years (17.3% vs. 20.1%; log-rank p=0.151), and 3 years after TAVR (30.7% vs. 31.2%; log-rank p=0.333). Conclusions DVI&amp;lt;0.5 was associated with higher peak gradients and lower baseline LVEF. DVI &amp;lt;0.5 group patients had lower 1-year mortality but similar mortality at 2 and 3-years of follow up. Funding Acknowledgement Type of funding sources: None. Figure 1. All-cause SurvivalFigure 2. Hemodynamic Data

Clinical Application of the Fluid Challenge Approach in Goal-Directed Fluid Therapy: What Can We Learn From Human Studies?

Resuscitative fluid therapy aims to increase stroke volume (SV) and cardiac output (CO) and restore/improve tissue oxygen delivery in patients with circulatory failure. In individualized goal-directed fluid therapy (GDFT), fluids are titrated based on the assessment of responsiveness status (i.e., the ability of an individual to increase SV and CO in response to volume expansion). Fluid administration may increase venous return, SV and CO, but these effects may not be predictable in the clinical setting. The fluid challenge (FC) approach, which consists on the intravenous administration of small aliquots of fluids, over a relatively short period of time, to test if a patient has a preload reserve (i.e., the relative position on the Frank-Starling curve), has been used to guide fluid administration in critically ill humans. In responders to volume expansion (defined as individuals where SV or CO increases ≥10–15% from pre FC values), FC administration is repeated until the individual no longer presents a preload reserve (i.e., until increases in SV or CO are <10–15% from values preceding each FC) or until other signs of shock are resolved (e.g., hypotension). Even with the most recent technological developments, reliable and practical measurement of the response variable (SV or CO changes induced by a FC) has posed a challenge in GDFT. Among the methods used to evaluate fluid responsiveness in the human medical field, measurement of aortic flow velocity time integral by point-of-care echocardiography has been implemented as a surrogate of SV changes induced by a FC and seems a promising non-invasive tool to guide FC administration in animals with signs of circulatory failure. This narrative review discusses the development of GDFT based on the FC approach and the response variables used to assess fluid responsiveness status in humans and animals, aiming to open new perspectives on the application of this concept to the veterinary field.

Hemodynamic monitoring by intracardiac impedance measured by cardiac resynchronization defibrillators: Evaluation in a controlled clinical setting (BIO.Detect HF II study)

BackgroundIn patients with cardiac resynchronization therapy defibrillators (CRT-Ds), intracardiac impedance measured by dedicated CRT-D software may be used to monitor hemodynamic changes. We investigated the relationship of hemodynamic parameters assessed by intracardiac impedance and by echocardiography in a controlled clinical setting. MethodsThe study enrolled 68 patients (mean age, 66 ± 9 years; 74% males) at 12 investigational sites. The patients had an indication for CRT-D implantation, New York Heart Association class II/III symptoms, left ventricular ejection fraction 15%–35%, and a QRS duration ≥150 ms. Two months after a CRT-D implantation, hemodynamic changes were provoked by overdrive pacing. Intracardiac impedance was recorded at rest and at four pacing rates ranging from 10 to 40 beats/min above the resting rate. In parallel, echocardiography measurements were performed. We hypothesized that a mean intra-individual correlation coefficient (rmean) between stroke impedance (difference between end-systolic and end-diastolic intracardiac impedance) measured by CRT-D and the aortic velocity time integral (i.e., stroke volume) determined by echocardiography would be significantly larger than 0.65. ResultsThe hypothesis was evaluated in 40 patients with complete data sets. The rmean was 0.797, with a lower confidence interval bound of 0.709. The study hypothesis was met (p = 0.007). A stepwise reduction of stroke impedance and stroke volume was observed with increasing heart rate. ConclusionsIntracardiac impedance measured by implanted CRT-Ds correlated well with the aortic velocity time integral (stroke volume) determined by echocardiography. The impedance measurements bear potential and are readily available technically, not requiring implantation of additional material beyond standard CRT-D system.

The Feasibility of a Novel Index From a Wireless Doppler Ultrasound Patch to Detect Decreasing Cardiac Output in Healthy Volunteers.

ABSTRACTIntroductionEarly hemorrhage is often missed by traditional vital signs because of physiological reserve, especially in the young and healthy. We have developed a novel, wearable, wireless Doppler ultrasound patch that tracks real-time blood velocity in the common carotid artery.Materials and MethodsWe studied eight healthy volunteers who decreased their cardiac output using a standardized Valsalva maneuver. In all eight, we simultaneously monitored the velocity time integral (VTI) of the common carotid artery (using the ultrasound patch) as well as the descending aorta (using a traditional pulsed wave duplex imaging system); the descending aortic VTI was used as a surrogate for left ventricular stroke volume (SV). Additionally, in a subset of four, we simultaneously measured SV using a noninvasive pulse contour analysis device.ResultsFrom baseline to peak effect of Valsalva, there was a statistically significant fall in descending aortic and common carotid VTI of 37% (P = 0.0005) and 23% (P < 0.0001), respectively. Both values returned to baseline on recovery. Additionally, a novel index from the carotid ultrasound patch (i.e., the heart rate divided by the carotid artery VTI) detected a 10% fall in aortic VTI with high sensitivity and specificity (100% and 100%, respectively); this novel index also accurately detected a 10% decrease in SV as measured by the noninvasive SV monitor. The mean arterial pressure, measured by the noninvasive pulse contour device, did not correctly detect the fall in SV.ConclusionIn summary, a novel index from a wireless Doppler ultrasound patch may be more sensitive and specific for detecting decreased cardiac output than standard vital signs in healthy volunteers.

Ultraprotective ventilation allowed by extracorporeal CO2 removal improves the right ventricular function in acute respiratory distress syndrome patients: a quasi-experimental pilot study

BackgroundRight ventricular (RV) failure is a common complication in moderate-to-severe acute respiratory distress syndrome (ARDS). RV failure is exacerbated by hypercapnic acidosis and overdistension induced by mechanical ventilation. Veno-venous extracorporeal CO2 removal (ECCO2R) might allow ultraprotective ventilation with lower tidal volume (VT) and plateau pressure (Pplat). This study investigated whether ECCO2R therapy could affect RV function.MethodsThis was a quasi-experimental prospective observational pilot study performed in a French medical ICU. Patients with moderate-to-severe ARDS with PaO2/FiO2 ratio between 80 and 150 mmHg were enrolled. An ultraprotective ventilation strategy was used with VT at 4 mL/kg of predicted body weight during the 24 h following the start of a low-flow ECCO2R device. RV function was assessed by transthoracic echocardiography (TTE) during the study protocol.ResultsThe efficacy of ECCO2R facilitated an ultraprotective strategy in all 18 patients included. We observed a significant improvement in RV systolic function parameters. Tricuspid annular plane systolic excursion (TAPSE) increased significantly under ultraprotective ventilation compared to baseline (from 22.8 to 25.4 mm; p < 0.05). Systolic excursion velocity (S’ wave) also increased after the 1-day protocol (from 13.8 m/s to 15.1 m/s; p < 0.05). A significant improvement in the aortic velocity time integral (VTIAo) under ultraprotective ventilation settings was observed (p = 0.05). There were no significant differences in the values of systolic pulmonary arterial pressure (sPAP) and RV preload.ConclusionLow-flow ECCO2R facilitates an ultraprotective ventilation strategy thatwould improve RV function in moderate-to-severe ARDS patients. Improvement in RV contractility appears to be mainly due to a decrease in intrathoracic pressure allowed by ultraprotective ventilation, rather than a reduction of PaCO2.

Repeat balloon valvuloplasty for dogs with recurrent or persistent pulmonary stenosis

Introduction/ObjectivesPulmonary stenosis (PS) is a common congenital defect in the dog. Severe valvar PS can be treated with balloon valvuloplasty (BV) to reduce obstruction severity and improve clinical signs. Repeat BV is often unnecessary, as restenosis is uncommon. Repeated pulmonary BV in people is generally successful and safe, but outcomes in dogs with recurrent or persistent stenosis have not been reported. The objectives of this study were to retrospectively evaluate outcomes of repeat BV in dogs. Animals, materials, and methodsMedical records and stored echocardiographic images were reviewed from dogs that received repeat BV for pulmonary valvar restenosis or persistent stenosis. Echocardiographic variables included maximum systolic ejection velocity (PVmax), velocity-derived maximal pressure gradient (PGmax) and velocity time integral (VTI) across the pulmonary valve, and ratios of pulmonic to aortic maximum velocity (PVmax/AVmax) and VTI (VTIPV/VTIAV). ResultsTwenty-three dogs were included; one underwent three BV procedures. The median time between BV procedures was 18.3 months (interquartile range, 6.3–43.6). One dog died during repeat BV, but no others experienced adverse effects. Reductions in PVmax, PGmax, and VTIPV after initial and repeat BV were 1.85 m/s, 76.2 mmHg, and 44.7 cm and 1.33 m/s, 55.6 mmHg, and 30.2 cm, respectively (all p < 0.01). Differences between pre-BV and post-BV PVmax, PGmax, VTIPV, PVmax/AVmax, and VTIPV/VTIAV were not different comparing initial to repeat BV (all p > 0.10). ConclusionsRepeat BV for recurrent or persistent PS is well tolerated and effective in a majority of dogs.

Impact of manual uterine displacement and left lateral tilt on echocardiographical velocity time intergral (stroke volume) in advanced pregnancy

Background. Pregnant women undergo a variety of physiological changes, and cardiac output (CO) is one of these important changes. During advanced pregnancy, aortocaval compression decreases CO by up to 30 - 40%. Such compression may cause adverse physiological disturbances in both the mother and the baby. Current practice is to nurse pregnant woman with at least 15° lateral tilt. Most studies have used non-invasive blood pressure measurement, which is not the gold standard and does not give a true depiction of the cardiac response to change in position. Objective. To determine the impact of manual uterine displacement (MUD) on cardiac stroke volume (SV) using the current most accurate non-invasive method, i.e. descending aorta velocity time integral (VTI) with echocardiography (ECHO). This method was used to ascertain the appropriate position to improve CO and provide superior uterine perfusion. Methods. A prospective case crossover study consisting of 22 women at 36 - 40 weeks of gestation was conducted. The studied positions were supine, 30° tilt, left lateral tilt and manual uterine displacement. Patients received a screening ECHO to ensure normal cardiac structure and function followed by measurement of the descending aorta VTI at each of the positions with 2-minute intervals between position changes . Results. There was a significant increase in the aortic VTI with all changes in position. The mean (standard deviation (SD)) change for supine-left lateral was 3.68 (0.74) ( p =0.00), supine-MUD was 3.29 (0.72) ( p =0.00) and supine-30° was 2.93 (0.72) ( p =0.00). No significant difference was found when the positions were compared with each other. Conclusion. Lateral tilt and MUD significantly increased descending aorta VTI (SV).

Influence of fasting duration on blood volume status of pediatric patients evaluated by ultrasonic technique

Objective: To evaluate the influence of preoperative fasting duration on blood volume status of pediatric patients during induction based on ultrasonic technique. Methods: One hundred and ten pediatric patients, scheduled for elective operation in the Second Affiliated Hospital & Yuying Children's Hospital, were recruited during January and October in 2018. After sedation by inhalation of sevoflurane, the maximum (expiratory) and minimum (inspiratory) diameter of inferior vena cava (IVC(max), IVC(min)) and aorta velocity-time integral (VTI) in apical five-chamber cardiac view were measured with an ultrasound machine. Respiratory variabilities of these parameters were further calculated. Furthermore, passive leg raising (PLR) test was performed and above measurements/calculations were repeated. The correlation between the duration of fasting and IVC respiratory variations index (IVC(RVI)) or aortic VTI variability (ΔVTI) was then analyzed. Results: Before PLR, IVC(max), IVC(min) and IVC(RVI) were (0.78±0.19), (0.43±0.15) cm and 0.45±0.12, respectively. After PLR, IVC(max) and IVC(min) increased to (0.94±0.20), (0.55±0.18) cm, while IVC(RVI) decreased to 0.42±0.13, the differences were statistically significant (t=15.66, 10.85, 3.14, all P<0.05). However, IVC(max), IVC(min) and IVC(RVI) were not significantly correlated with the duration of fasting analyzed by linear regression (before PLR: r=0.052, 0.163, 0.171; after PLR, r=0.062, 0.169, 0.165, all P>0.05). Before PLR, expiratory aortic VTI (VTI(max)), inspiratory aortic VTI (VTI(min)) and ΔVTI were 21±5, 17±4 and 17±8, respectively. After PLR, the VTI(max) and VTI(min) significantly increased to 23±5 and 19±4 (t=13.60, 10.43, all P<0.05), but ΔVTI was not changed significantly, which was 17±8(t=0.34, P>0.05). Linear regression analysis showed that VTI(max), VTI(min) and ΔVTI were not significantly correlated with the duration of fasting (before PLR: r=0.111, 0.100, 0.047; after PLR: r=0.003, 0.033, 0.073, all P>0.05). Further multiple linear regression analysis indicated that, age and body weight were independent factors influencing IVC(RVI) and ΔVTI before and after PLR (IVC(RVI): β=-0.441, 0.515, -0.451, 0.507; ΔVTI: β=-0.442, 0.545, -2.422, 2.850; all P<0.05). However, the duration of fasting was not correlated with IVC(RVI) and ΔVTI after adjusting the age and weight (IVC(RVI): β=0.177, 0.160; ΔVTI: β=0.037, 0.054; all P>0.05). Conclusion: Age and weight, but not preoperative fasting duration, are correlated with respiratory variabilities of inferior vena cava diameter and aortic VTI in pediatric patients.