Changes In Stroke Volume Index Research Articles

Comparison of the ability of short time low PEEP challenge and mini fluid challenge to predict fluid responsiveness in patients undergoing open pancreaticoduodenectomy: an observational cohort study.

The mini-fluid challenge (MFC), which assesses the change in stroke volume index (SVI) following the administration of 100 mL of crystalloids, and the short-time low positive end-expiratory pressure (PEEP) challenge (SLPC), which evaluates the temporary reduction in SVI due to a PEEP increment, are two functional hemodynamic tests used to predict fluid responsiveness in the operating room. However, SLPC has not been assessed in patients undergoing abdominal surgery, and there is no study comparing these two methods during laparotomy. Therefore, we aimed to compare the SLPC and MFC in patients undergoing open pancreaticoduodenectomy. All patients received a standard hemodynamic management. The study protocol evaluated the percentage change in SVI following the application of an additional 5 cmH2O PEEP (SVIΔ%-SLPC) and the infusion of 100 mL crystalloid (SVIΔ%-MFC). Challenges that resulted in an increase of more than 15% in SVI after the 500 ml of fluid loading were classified as positive challenges (PC). Areas under the receiver operating characteristics curves (ROC AUCs) were used for the comparison of the methods. Thirty-three patients completed the study with 94 challenges. Fifty-five (58.5%) of them were PCs. The ROC AUC of SVIΔ%-MFC was observed to be significantly higher than that of SVIΔ%-SLPC (0.97 vs. 0.64, p < 0.001). The best cut-off value for SVIΔ%-MFC was 5.6%. If we had stopped the bolus fluid administration when SVIΔ%-MFC ≤ 5% was observed (lower limit of the gray zone), we would have postponed the fluid loading in 35 (89.7%) of 39 negative challenges. The amount of fluid deferred would have corresponded to up to 40% of the total fluid given. SVIΔ%-MFC predicts fluid responsiveness with high diagnostic performance and is better than SVIΔ%-SLPC in patients undergoing open pancreatoduodenectomy. Additionally, the use of SVIΔ%-MFC has the potential to defer up to 40% of the total fluid given. gov: NCT05419570.

PREDICTION OF FLUID RESPONSIVENESS WITH CRYSTALLOID MINI-FLUID CHALLENGE IN CRITICALLY ILL PATIENTS

Background: The mini-fluid challenge test is a good predictor and has minimal limitations in determining fluid responsiveness in the critically ill. However, it primarily relies on colloid infusion. The availability of colloids may vary among hospitals in resource-limited countries, and they can be more expensive than crystalloid fluids. Objective: The study aimed to use crystalloids instead of colloids to predict fluid responsiveness. Methods: This study was conducted from August 2022 to February 2023 among patients with shock in the medical ICU to assess fluid responsiveness. Arterial and central venous catheters were used for the intravenous infusion and monitoring. Data were collected during two consecutive crystalloid mini-fluid challenges of 50 mL each in 1 minute, 100 mL in 2 minutes, and a standard fluid challenge of 300 mL over 15 minutes. The objective was to predict a stroke volume index (SVI) increase of &gt; 10%. Diagnostic accuracy was evaluated using the Receiver Operating Characteristic (ROC) curve, and hemodynamic variables in the positive fluid challenge group were compared for different volume expansions. Results: Twenty-nine patients (62% males; median age, 75 years) were included, with 42 fluid challenge test events. Septic shock was the primary condition in 83% of the cases. The 50 mL crystalloid mini-fluid challenge showed an accuracy of 80% with a sensitivity of 69% and specificity of 100% at the cutoff level of SVI &gt; 5%, Area Under ROC (AUROC)=0.79. In comparison, the 100 mL crystalloid mini-fluid challenge demonstrated an accuracy of 85% (sensitivity of 79% and specificity of 100%) at the cutoff level of SVI &gt; 10% (AUROC= 0.89). In the positive fluid challenge group, administration of crystalloids led to a significant increase in mean arterial pressure and SVI, while other parameters remained comparable. Conclusions: A mini-fluid challenge test with 100 mL crystalloids can predict fluid responsiveness in critically ill patients. The best cutoff level was a change in SVI &gt; 10% from baseline.

Assessing Fluid Responsiveness Using Noninvasive Hemodynamic Monitoring in Pediatric Shock: A Review

AbstractNoninvasive hemodynamic monitoring devices have been introduced to better quantify fluid responsiveness in pediatric shock; however, current evidence for their use is inconsistent. This review aims to examine available noninvasive hemodynamic monitoring techniques for assessing fluid responsiveness in children with shock. A comprehensive literature search was conducted using PubMed and Google Scholar, examining published studies until December 31, 2022. Articles were identified using initial keywords: [noninvasive] AND [fluid responsiveness]. Inclusion criteria included age 0 to 18, use of noninvasive techniques, and the emergency department (ED) or pediatric intensive care unit (PICU) settings. Abstracts, review papers, articles investigating intraoperative monitoring, and non-English studies were excluded. The methodological index for nonrandomized studies (MINORS) score was used to assess impact of study bias and all study components were aligned with Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. Our review yielded 1,353 articles, 17 of which met our inclusion criteria, consisting of 618 patients. All were prospective observational studies performed in the ED (n = 3) and PICU (n = 14). Etiologies of shock were disclosed in 13/17 papers and consisted of patients in septic shock (38%), cardiogenic shock (29%), and hypovolemic shock (23%). Noninvasive hemodynamic monitors included transthoracic echocardiography (TTE) (n = 10), ultrasonic cardiac output monitor (USCOM) (n = 1), inferior vena cava ultrasonography (n = 2), noninvasive cardiac output monitoring (NICOM)/electrical cardiometry (n = 5), and &gt;2 modalities (n = 1). To evaluate fluid responsiveness, most commonly examined parameters included stroke volume variation (n = 6), cardiac index (CI) (n = 6), aortic blood flow peak velocity (∆V peak) (n = 3), and change in stroke volume index (n = 3). CI increase &gt;10% predicted fluid responsiveness by TTE in all ages; however, when using NICOM, this increase was only predictive in children &gt;5 years old. Additionally, ∆SV of 10 to 13% using TTE and USCOM was deemed predictive, while no studies concluded distensibility index by transabdominal ultrasound to be significantly predictive. Few articles explore implications of noninvasive hemodynamic monitors in evaluating fluid responsiveness in pediatric shock, especially in the ED setting. Consensus about their utility remains unclear, reiterating the need for further investigations of efficacy, accuracy, and applicability of these techniques.

The effect of a novel lifestyle intervention on autonomic and haemodynamic function in individuals with hypertrophic cardiomyopathy

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement no. 777204. Background Autonomic nervous system may play an important role in the pathophysiology of hypertrophic cardiomyopathy (HCM). Lifestyle interventions have been shown to improve signs and symptoms in individuals with heart failure. Purpose To evaluate the effect of a novel lifestyle intervention incorporating physical activity and dietary nitrate supplementation on cardiac autonomic and haemodynamic function in individuals with HCM. Methods Twenty-eight individuals with HCM were recruited into a single-centre pilot study (N=7 females, age 54±15 years) and randomised into the intervention (N=20) or control (N=8) group. Participants completed short-term (5-minute) non-invasive heart rate variability (HRV) measurements under resting (supine) conditions using the TaskForce (CNSystems, Graz, Austria). Frequency-domain HRV measures including spectral analysis of RR interval (i.e. absolute and normalised low frequency power (LF), high frequency power (HF) and LF/HF ratio) were recorded. Non-invasive haemodynamic variables including cardiac output (CO), and stroke volume (SV)were simultaneously recorded using bioimpedance technology integrated within the TaskForce. Intervention participants consumed 6 mmol of nitrate daily (concentrated beetroot juice) and increased and maintained their daily physical activity by ≥2000 steps/day above baseline for 16 weeks. Participants in the control group continued with their usual lifestyle and monitored daily step counts. Physical activity was evaluated objectively using pedometers (Omron Health, Japan). All participants were monitored weekly via telephone calls and average daily activity levels were recorded using diaries. However, participants in the control group were asked not to change their physical activity and dietary habits. Results Participants in the intervention group significantly increased their average physical activity by 3029 steps post intervention (i.e, 6234±2389 vs 9263± 3341 steps/day, p&amp;lt;0.01) compared to control (7559±3257 vs 7604± 2901 steps/day, p=0.96). There was a significant increase in post-intervention HF power (7.54±2.14 vs. 8.78±1.60 ms2, p&amp;lt;0.01) and LF power (6.89±2.33 vs. 8.17±1.55, p&amp;lt;0.01) respectively, but not in the control group (i.e., HF (7.05±3.39 vs. 7.64±2.56 ms2, p=0.33) and LF power (6.78±3.31 vs. 7.06±2.43 ms2 p=0.63)). There was a non-significant change in SV index in the intervention (33±9.83 vs. 29±8.56 ml/beat/m2, p=0.06) and control groups (34±6.27 vs. 33±8.1 ml/beat/m2, p=0.79). Similarly, there was no significant change in cardiac index in the intervention or control groups (intervention: 2.35±0.44 vs. 2.38±0.52 L/min/m2, p=0.77; control: 2.27±0.40 vs. 2.67±0.78, p=0.06). Conclusions Lifestyle intervention incorporating physical activity and dietary nitrate supplementation led to a significant increase in daily physical activity and improved parasympathetic activity in hypertrophic cardiomyopathy.

Effects of tidal volume challenge on the reliability of plethysmography variability index in hepatobiliary and pancreatic surgeries: a prospective interventional study

BackgroundThe plethysmography variability index (PVI) is a non-invasive, real-time, and automated parameter for evaluating fluid responsiveness, but it does not reliably predict fluid responsiveness during low tidal volume (VT) ventilation. We hypothesized that in a ‘tidal volume challenge’ with a transient increase in tidal volume from 6 to 8 ml Kg− 1, the changes in PVI could predict fluid responsiveness reliably.MethodWe performed a prospective interventional study in adult patients undergoing hepatobiliary or pancreatic tumor resections and receiving controlled low VT ventilation. The values for PVI, perfusion index, stroke volume variation, and stroke volume index (SVI) were recorded at baseline VT of 6 ml Kg− 1, 1 min after the VT challenge (8 ml Kg− 1), 1 min after VT 6 ml Kg− 1 reduced back again, and then 5 min after crystalloid fluid bolus 6 ml kg− 1 (actual body weight) administered over 10 min. The fluid responders were identified by SVI rise ≥ 10% after the fluid bolus.ResultsThe area under the receiver operating characteristic curve for PVI value change (ΔPVI6–8) after increasing VT from 6 to 8 ml Kg− 1 was 0.86 (95% confidence interval, 0.76–0.96), P < 0.001, 95% sensitivity, 68% specificity, and with best cut-off value of absolute change (ΔPVI6–8) = 2.5%.ConclusionIn hepatobiliary and pancreatic surgeries, tidal volume challenge improves the reliability of PVI for predicting fluid responsiveness and changes in PVI values obtained after tidal volume challenge are comparable to the changes in SVI.

Carotid doppler indices do not predict fluid responsiveness in mechanically ventilated patients undergoing coronary artery bypass grafting surgery.

This study aimed to determine the predictive value of carotid artery blood flow (CABF), corrected carotid flow time (CFT), and respiratory variation in carotid peak systolic velocity (DVPeakCA) for fluid responsiveness in mechanically ventilated patients undergoing coronary artery bypass grafting (CABG) surgery. It also aimed to correlate each of these indices with changes in stroke volume index (SVI) after a fluid bolus. This prospective, interventional, before-after study recruited 45adult patients undergoing CABG. Following induction of anesthesia, a fluid challenge of 6 ml/kg of a crystalloid solution was delivered over 10 min. Mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), CABF, CFT, and DVPeakCA were recorded before and following the intervention. Patients with an increase in SVI of >15% from baseline were considered responders. We had 22 responders and 23 nonresponders. Areas under the receiver operating characteristic (AUROC) curves for the studied indices (CABF, 0.516, CFT, 0.502, and DVPeakCA, 0.671) did not suggest any strong predictive value to detect fluid responsiveness. Similarly, the r values for correlation of these carotid doppler-derived indices, both baseline and as % change from baseline with the % alteration of SVI were all <0.2, which demonstrates a very weak correlation between these variables. Carotid doppler indices are unreliable to assess fluid responsiveness, and cannot replace invasive methods of analyzing preload optimization. There was no significant correlation between carotid doppler-derived indices and alterations in SVI before and after the fluid bolus.

Reliability of bioreactance-derived hemodynamic monitoring during simulated sustained gravitational transitions induced by short-arm human centrifugation.

Precise, sensitive, and non-invasive estimates of stroke volume index (SVI) would facilitate clinical decision making and tracking of cardiorespiratory fitness in space. Thoracic electrical bioreactance (TEBR) is capable of providing valid SVI estimates on Earth; however, its reliability in response to simulated sustained gravitational transitions is unknown. Ten healthy male subjects underwent short-arm human centrifugation (SAHC) equivalent to 1g and 1.5g at their center of mass along the z-axis (gz) for 10min each (first 5min: passive; last 5min: active, leg press movements), interspersed by periods without centrifugation (µg). The TEBR-based device Starling™ SV was used to estimate SVI during the five distinct passive gz phases. Precision of SVI measurements and sensitivity to hemodynamic changes induced by simulated gz transitions were determined. Overall SVI precision was very high (coefficient of variation=3.6%), whereas mean sensitivity to SVI changes was satisfactory (sensitivity index=75%). This study shows that the TEBR-based device Starling™ SV is precise and sensitive to hemodynamic changes in response to simulated sustained gz transitions induced by SAHC. Thus, it may be a suitable non-invasive hemodynamic monitor during human spaceflight. Further evaluation of Starling™ SV against a reference method in simulated microgravity is warranted.

Detecting Volemic, Cardiac, and Autonomic Responses From Hypervolemia to Normovolemia via Non-Invasive ClearSight Hemodynamic Monitoring During Hemodialysis: An Observational Investigation.

Background: Unstable hemodynamics are not uncommon during hemodialysis (HD), which involves a rapid volume depletion, taking the patient from hypervolemia toward euvolemia. Since uremic patients commonly have cardiovascular comorbidities, hemodynamic changes during HD may reflect interactions among the volemic, cardiac, and autonomic responses to gradual volume depletion during ultrafiltration. Accurate identification of inappropriate responses helps with precisely managing intradialytic hypotension. Recently, the non-invasive ClearSight was reported to be able to detect causes of intraoperative hypotension. In this prospective observational study, we aimed to determine whether ClearSight could be used to detect patterns in stroke volemic, cardiac, and vasoreactive responses during HD. Methods: ClearSight was used to monitor chronic stable patients receiving maintenance HD. Data of mean arterial blood pressure (MAP), heart rate (HR), stroke volume index (SVI), cardiac index (CI), and calculated systemic vascular resistance index (SVRI) were obtained and analyzed to examine patterns in volemic, cardiac, and vasoreactive changes from T0 (before HD) until T8 in 30-min intervals (total 4 h). Results: A total of 56 patients with a mean age of 60.5 years were recruited, of which 40 of them were men. The average ultrafiltration volume at T8 was 2.1 ± 0.8 L. The changes in MAP and HR from T0 to T8 were non-significant. SVI at T7 was significantly lower than that at T1, T2, and T3. CI at T4 to T8 was significantly lower than that at T0. SVRI was significantly higher at T3 to T8 than at T0. Pearson’s correlation coefficients between SVI and CI and between SVRI and MAP were positive at all time points. The correlation coefficients between SVRI and SVI and between CI and SVRI were significant and negative for all time points. Conclusion: ClearSight was able to detect patterns in hypervolemia during HD and was well tolerated for 4 h. CI decreased significantly after T4, with slightly decreased SVI. Ultrafiltration volume was not correlated with changes in SVI or CI. The vascular tone increased significantly, and this counteracted the reduced cardiac output after T4. With simultaneous monitoring on SVI, CI, and SVRI during HD, therefore, hypotension could be detected and managed by reducing the filtration rate or administering inotrope or vasopressors. Trial Registration: clinicaltrials.gov, ID: NCT03901794.

Does Hemodynamic Response to Inotropes Predict Early Right Heart Failure After LVAD Implantation?

<h3>Purpose</h3> Right ventricular (RV) failure is a highly morbid clinical condition following left ventricular assist device (LVAD) implantation. We aimed to compare baseline and post-inotrope(s) hemodynamics as predictors of early right heart failure (RHF) after LVAD implantation. <h3>Methods</h3> We performed a single-center, retrospective analysis of all patients implanted with an LVAD between January 2018 and September 2020. We included patients with pre-implant baseline hemodynamics without augmentation by inotropic or mechanical circulatory support (MCS). This cohort was then placed on inotrope(s) with documented hemodynamics at 24 hours. We then utilized the Academic Research Consortium early RHF criteria to define severe-acute RHF (requirement of assist device or high dose inotropes with end-organ dysfunction). Stroke volume index (SVI) was identified as a surrogate of RV inotropic reserve. Comparisons between patients with and without early RHF were made using Fisher's Exact and Chi-Square tests, with probabilities determined by a binary logistical regression model. <h3>Results</h3> A total of 48 patients met study inclusion criteria. Early post-implant RHF was noted in 45.8% (n=22) of this population. There were no statistical differences among these groups when evaluated for type of inotrope utilized (p=0.2126), change in cardiac index (p=0.8924), or change in SVI (p=0.5659). There was, however, a nonsignificant trend towards decreased probability of development of early RHF, as evidenced by percent improvement in post-inotrope(s) SVI. This was most apparent in patients who received milrinone monotherapy (Figure). <h3>Conclusion</h3> We observed a nonsignificant trend of improved RV inotropic reserve represented by improvement in post-inotrope SVI, which numerically correlated with less early RHF.

Ability of short-time low peep challenge to predict fluid responsiveness in mechanically ventilated patients in the intensive care.

Short-time low PEEP challenge (SLPC, application of additional 5 cmH2O PEEP to patients for 30 s) is a novel functional hemodynamic test presented in the literature. We hypothesized that SLPC could predict fluid responsiveness better than stroke volume variation (SVV) in mechanically ventilated intensive care patients. Heart rate, mean arterial pressure, stroke volume index (SVI) and SVV were recorded before SLPC, during SLPC and before and after 500 mL fluid loading. Patients whose SVI increased more than 15% after the fluid loading were defined as fluid responders. Reciever operating characteristics (ROC) curves were generated to evaluate the abilities of the methods to predict fluid responsiveness. Fifty-five patients completed the study. Twenty-five (46%) of them were responders. Decrease percentage in SVI during SLPC (SVIΔ%–SLPC) was 11.6 ± 5.2% and 4.3 ± 2.2% in responders and non-responders, respectively (p < 0.001). A good correlation was found between SVIΔ%–SLPC and percentage change in SVI after fluid loading (r = 0.728, P < 0.001). Areas under the ROC curves (ROC–AUC) of SVIΔ%–SLPC and SVV were 0.951 (95% CI 0.857–0.991) and 0.747 (95% CI 0.611–0.854), respectively. The ROC–AUC of SVIΔ%–SLPC was significantly higher than that of SVV (p = 0.0045). The best cut-off value of SVIΔ%–SLPC was 7.5% with 90% sensitivity and 96% specificity. The percentage change in SVI during SLPC predicts fluid responsiveness in intensive care patients who are ventilated with low tidal volumes; the sensitivity and specificity values are higher than those of SVV.

Predictive value of carotid ultrasound in combination with passive leg raising on fluid responsiveness in critically ill patients

To investigate the value of monitor carotid velocity time integral (VTI) and corrected flow time (FTc) by bedside ultrasound before and after passive leg raising (PLR) in predicting fluid responsiveness in critically ill patients. A prospective observational study was conducted. Fifty patients with critical illness admitted to the First People's Hospital of Fuyang Hangzhou from January 2020 to March 2021 were enrolled. The clinical data including the gender, age, body mass index (BMI), acute physiology and chronic health evaluation II (APACHE II) score, and the duration of mechanical ventilation were recorded. The changes of carotid VTI and FTc were measured by bedside ultrasound, and the values of heart rate, mean arterial pressure (MAP), central venous pressure (CVP), stroke volume index (SVI), and intrathoracic blood volume index (ITBVI) were measured by pulse indicated continuous cardiac output (PiCCO) monitor before and after PLR in all patients. According to the changes of SVI before and after PLR, the patients were divided into fluid responsiveness positive group with the change rate of SVI ≥ 15% and fluid responsiveness negative group with the change rate of SVI < 15%. The differences in the values of VTI, FTc, CVP, and ITBVI obtained before and after PLR (ΔVTI, ΔFTc, ΔCVP and ΔITBVI) were calculated and then compared between the two groups. The predictive values of these indicators on fluid responsiveness in critically ill patients were analyzed by receiver operator characteristic curve (ROC curve), and their relationship with the difference in SVI (ΔSVI) obtained before and after PLR was evaluated by Pearson correlation analysis. Fifty patients were all enrolled in this study, in which 27 patients were fluid response and 23 patients were fluid nonresponse. Basic clinical data were not different between the two groups. The values of ΔVTI, ΔFTc, ΔCVP, and ΔITBVI in fluid response were all significantly higher than those in fluid nonresponse [ΔVTI (cm): 2.07±1.16 vs. 0.67±0.86, ΔFTc (ms): 4.00±6.10 vs. 0.01±2.26, ΔCVP (cmH2O, 1 cmH2O = 0.098 kPa): 1.67±1.14 vs. 1.00±1.17, ΔITBVI (mL/m2): 98±69 vs. 48±70, all P < 0.05]. ROC curve analysis showed that ΔVTI, ΔFTc, ΔCVP and ΔITBVI were all positive for predicting fluid responsiveness, their area under ROC curve (AUC) and 95% confidence interval (95%CI) were 0.870 (0.769-0.972), 0.694 (0.547-0.841), 0.684 (0.535-0.832) and 0.709 (0.564-0.855), respectively. When using ΔVTI 0.92 cm, ΔFTc 1.45 ms, ΔCVP 1.50 cmH2O and ΔITBVI 44.50 mL/m2 as the threshold values, the sensitivities were 96.3%, 63.0%, 44.4% and 81.5%, and the specificities were 65.2%, 78.3%, 82.6% and 56.5%, respectively, in which the predictive value of ΔVTI was the largest. Pearson correlation analysis indicated that ΔVTI, ΔFTc, ΔCVP, and ΔITBVI were positively associated with ΔSVI (r values were 0.971, 0.334, 0.440, 0.650, P values were 0.000, 0.018, 0.001, 0.000, respectively). Carotid ΔVTI and ΔFTc monitored by bedside ultrasound before and after PLR could be as effective as conventional indicators in predicting fluid responsiveness in critically ill patients, and the predictive value of ΔVTI was better than others.

Effect of leg lift on stroke volume index in children 11-17 years old before and after induction of general anesthesia.

Fluid administration in ERAS is one component which anesthesiologists have control. Change in stroke volume index (SVI) is used to assess fluid responsiveness. This study sought the effect of perioperative fluid responsiveness in pediatric patients. The Cheetah NICOM™ (noninvasive CO monitor) was employed because of correlation with other CO monitors. The Cheetah NICOM™ is an FDA-approved device in adults. Its indications in children are unknown. 24 enrolled patients (age 11-17) were ASA 1 or 2 without cardiopulmonary disease. The study examined changes in SVI, HR, SBP, and DBP between the semi-recumbent and legs lifted positions, both awake and after anesthesia. Each patient had baseline vital signs measured and fluid responsiveness determined with the Cheetah NICOM™ monitor. Stroke volume index (SVI) was measured in both the semi-recumbent position and after passive leg lift. Measurements were repeated immediately after induction of general anesthesia. Twenty-one of 24 patients received inhalation induction with sevoflurane and three patients received intravenous propofol followed by sevoflurane. Airway management included intubation in 19 of 24 and a laryngeal mask airway (LMA) in five of 24 patients. There was a 25% increase in SVI after leg lift from 54.8ml/m2 to 68.0ml/m2 in awake patients (p &lt; 0.001). Diastolic pressure decreased by 15.4% from 67.9mmHg to 58.2mmHg from semi-recumbent position and leg lift, respectively (p=.004). No significant change in heart rate or SBP was found. Following induction, patient SVI increased with leg lift by 25.6% from 42.6ml/m2 to 53.5ml/m2 after leg lift (p=.003). Heart rate decreased by 9.3% and SBP increased 2.8% with leg lift. 96% of normal 11-17-year-old children were fluid responsive while awake and 79% after induction of general anesthesia.

Mini fluid chAllenge aNd End-expiratory occlusion test to assess flUid responsiVEness in the opeRating room (MANEUVER study): A multicentre cohort study.

The fluid challenge response in surgical patients can be predicted by functional haemodynamic tests. Two tests, the mini-fluid challenge (mini-FC) and end-expiratory occlusion test (EEOT), have been assessed in a few small single-centre studies with conflicting results. In general, functional haemodynamic tests have not performed reliably in predicting fluid responsiveness in patients undergoing laparotomy. This trial is designed to address and compare the reliability of the EEOT and the mini-FC in predicting fluid responsiveness during laparotomy. Prospective, multicentre study. Three university hospitals in Italy. A total of 103 adults patients scheduled for elective laparotomy with invasive arterial monitoring. The study protocol evaluated the changes in the stroke volume index (SVI) 20 s (EEOT20) and 30 s (EEOT30) after an expiratory hold and after a mini-FC of 100 ml over 1 min. Fluid responsiveness required an increase in SVI at least 10% following 4 ml kg-1 of Ringer's solution fluid challenge infused over 10 min. Haemodynamic data, including SVI, were obtained from pulse contour analysis. The area under the receiver operating characteristic curves of the tests were compared with assess fluid responsiveness. Fluid challenge administration induced an increase in SVI at least 10% in 51.5% of patients. The rate of fluid responsiveness was comparable among the three participant centres (P = 0.10). The area under the receiver operating characteristic curves (95% CI) of the changes in SVI after mini-FC was 0.95 (0.88 to 0.98), sensitivity 98.0% (89.5 to 99.6) and specificity 86.8% (75.1 to 93.4) for a cut-off value of 4% of increase in SVI. This was higher than the SVI changes after EEOT20, 0.67 (0.57 to 0.76) and after EEOT30, 0.73 (0.63 to 0.81). In patients undergoing laparotomy the mini-FC reliably predicted fluid responsiveness with high-sensitivity and specificity. The EEOT showed poor discriminative value and cannot be recommended for assessment of fluid responsiveness in this surgical setting. NCT03808753.

Volume Infusion Markedly Increases Femoral dP/dtmax in Fluid-Responsive Patients Only.

To evaluate the preload dependence of femoral maximal change in pressure over time (dP/dtmax) during volume expansion in preload dependent and independent critically ill patients. Retrospective database analysis. Two adult polyvalent ICUs. Twenty-five critically ill patients with acute circulatory failure. Thirty-five fluid infusions of 500 mL normal saline. Changes in femoral dP/dtmax, systolic, diastolic, and pulse femoral arterial pressure were obtained from the pressure waveform analysis using the PiCCO2 system (Pulsion Medical Systems, Feldkirchen, Germany). Stroke volume index was obtained by transpulmonary thermodilution. Statistical analysis was performed comparing results before and after volume expansion and according to the presence or absence of preload dependence (increases in stroke volume index ≥ 15%). Femoral dP/dtmax increased by 46% after fluid infusion in preload-dependent cases (mean change = 510.6 mm Hg·s; p = 0.005) and remained stable in preload-independent ones (mean change = 49.2 mm Hg·s; p = 0.114). Fluid-induced changes in femoral dP/dtmax correlated with fluid-induced changes in stroke volume index in preload-dependent cases (r = 0.618; p = 0.032), but not in preload-independent ones. Femoral dP/dtmax strongly correlated with pulse and systolic arterial pressures and with total arterial stiffness, regardless of the preload dependence status (r > 0.9 and p < 0.001 in all cases). Femoral dP/dtmax increased with volume expansion in case of preload dependence but not in case of preload independence and was strongly related to pulse pressure and total arterial stiffness regardless of preload dependence status. Therefore, femoral dP/dtmax is not a load-independent marker of left ventricular contractility and should be not used to track contractility in critically ill patients.

Comparison of the ability of two continuous cardiac output monitors to detect stroke volume index: Estimated continuous cardiac output estimated by modified pulse wave transit time and measured by an arterial pulse contour-based cardiac output device.

Estimated continuous cardiac output (esCCO), a non-invasive technique for continuously measuring cardiac output (CO), is based on modified pulse wave transit time, which is determined by pulse oximetry and electrocardiography. We examined the ability of esCCO to detect stroke volume index (SVI) and changes in SVI compared with currently available arterial waveform analysis methods. We retrospectively reanalysed 15 of the cases from our previous study on esCCO measurement. SVI was calculated using an esCCO system, measured using the arterial pressure-based CO (APCO) method, and compared with a corresponding intermittent bolus thermodilution CO (ICO) method. Percentage error measurement and statistical methods, including concordance analysis and polar plot analysis, were performed. The difference in the SVI values between esCCO and ICO was -3.0 ± 8.8 ml (percentage error, 33.5%). The mean angular bias was 0.8 and the radial limits of agreement were ± 27.3. The difference in the SVI values between APCO and ICO was 0.9 ± 11.2 ml (percentage error, 42.6%). The mean angular bias was -6.8 and the radial limits of agreement were ± 44.1. This study demonstrated that the accuracy, precision, and dynamic trend of esCCO are better than those of APCO.

Utility of changes in end-tidal carbon dioxide after volume expansion to assess fluid responsiveness in the operating room: a prospective observational study

BackgroundFrom a physiological viewpoint, changes in end-tidal carbon dioxide (EtCO2) could be a simple, noninvasive, and inexpensive way to monitor changes in cardiac index. This study aimed to assess the utility of changes in EtCO2 as a marker of fluid responsiveness after volume expansion in the operating room. MethodsA prospective observational study was conducted in a tertiary university teaching hospital, from August 2018 to February 2019. A total of 109 non-consecutive, mechanically ventilated adults undergoing neurosurgery in the supine position with cardiac output monitors were included. Patients with major respiratory disease, arrhythmia, or heart failure were excluded. Volume expansion with 250 ml of saline 0.9% was performed over 10 min to maximise cardiac output during surgery, according to current guidelines. A positive fluid challenge was defined as an increase in stroke volume index of more than 10% from baseline. Changes in stroke volume index (monitored using pulse contour analysis) and EtCO2 were recorded before and after infusion. ResultsA total of 242 fluid challenges in 114 patients were performed, of which 26.9% were positive. Changes in EtCO2 > 1.1% induced by infusions had utility for identifying fluid responsiveness, with a sensitivity of 62.9% (95% confidence interval [CI], 62.5–63.3%) and a specificity of 77.8% (95% CI, 77.6–78.1%). The area under the receiver operating characteristic curve for changes in EtCO2 after volume expansion was 0.683 (95% CI, 0.680–0.686). ConclusionsChanges in EtCO2 induced by rapid infusion of 250 ml saline 0.9% lacked accuracy for identifying fluid responsiveness in mechanically ventilated patients in the operating room. Clinical trial registrationNCT03635307.

Assessment of Fluid Responsiveness in Prone Neurosurgical Patients Undergoing Protective Ventilation: Role of Dynamic Indices, Tidal Volume Challenge, and End-Expiratory Occlusion Test.

In patients in the prone position, the reliability of pulse pressure variation and stroke volume variation (PPV and SVV) and the use of functional hemodynamic tests to predict fluid responsiveness have not previously been established. Perioperatively, in this setting, optimizing fluid management can be challenging, and fluid overload is associated with both intraoperative and postoperative complications. We designed this study to assess the sensitivity and specificity of baseline PPV and SVV, the tidal volume (VT) challenge (VTC) and the end-expiratory occlusion test (EEOT) in predicting fluid responsiveness during elective spinal surgery. The study protocol was started during a period of intraoperative hemodynamic stability after prone positioning and before the administration of any vasopressor: (1) at baseline, the controlled ventilation was set at 6 mL/kg of predicted body weight (PBW) (T0); (2) patients underwent the first EEOT (EEOT6) by interrupting the mechanical ventilation for 30 seconds; (3) the ventilation was set again at 6 mL/kg PBW for 1 minute (T1); (4) the VTC was applied by increasing the VT up to 8 mL/kg PBW for 1 minute; (5) the ventilation was kept at 8 mL/kg PBW for 1 minute (T2); (6) a second EEOT (EEOT8) was performed; (7) the VT was reduced back to 6 mL/kg PBW for 1 minute (T3); (8) a fluid challenge of 250 mL of Ringer's solution was infused over 10 minutes. After each step, a complete set of hemodynamic measurements was recorded. Neither PPV and SVV values recorded at T3 nor the EEOT6 or the EEOT8 predicted fluid responsiveness. The change in PPV after VTC application predicted fluid responsiveness with an area under the curve of 0.96 (95% confidence interval, 0.87-1.00), showing a sensitivity of 95.2% and a specificity of 94.7%, using a cutoff increase of 12.2%. The change in SVV after VTC application predicted fluid responsiveness with an area under the curve 0.96 (95% confidence interval, 0.89-1.00) showing a sensitivity of 95.2% and a specificity of 94.7%, using a cutoff increase of 8.0%. A linear correlation between stroke volume index changes after fluid challenge administration and the changes in PPV and SVV after VTC application was observed (r = 0.71; P < .0001 and r = 0.68; P < .0001, respectively). In prone elective neurosurgical patients, the baseline values of PPV and SVV and the EEOT fail to predict fluid responsiveness, while the VTC is a very reliable functional hemodynamic test and could be helpful in guiding intraoperative fluid therapy.

Precision and consistency of the passive leg raising maneuver for determining fluid responsiveness with bioreactance non-invasive cardiac output monitoring in critically ill patients and healthy volunteers.

ObjectiveThe passive leg raising (PLR) maneuver has become standard practice in fluid resuscitation. We aim to investigate the precision and consistency of the PLR for determining fluid responsiveness in critically ill patients and healthy volunteers using bioreactance non-invasive cardiac output monitoring (NiCOM™, Cheetah Medical, Inc., Newton Center, Massachusetts, USA).MethodsThis study is prospective, single-center, observational cohort with repeated measures in critically ill patients admitted to the medical intensive care unit and healthy volunteers at a tertiary academic medical center. Three cycles of PLR were performed, each at 20–30 minutes apart. Fluid responsiveness was defined as a change in stroke volume index (ΔSVI) > 10% with each PLR as determined by NiCOM™. Precision was the variability in ΔSVI after the 3 PLR’s, and determined by range, average deviation and standard deviation. Consistency was the same fluid responsiveness determination of “Yes” (ΔSVI > 10%) or “No” (ΔSVI ≤ 10%) for all 3 PLR’s.ResultsSeventy-five patients and 25 volunteers were enrolled. In patients, the precision was range of 17.2±13.3%, average deviation 6.5±4.0% and standard deviation 9.0±5.2%; and for volunteers, 17.4±10.3%, 6.6±3.8% and 9.0±6.7%, respectively. There was no statistical difference in the precision measurements between patients and volunteers. Forty-nine (65.3%) patients vs. twenty-four (96.0%) volunteers had consistent results, p < 0.01. Among those with consistent results, twenty-four (49.0%) patients and 24 (100%) volunteers were fluid responsive.ConclusionsThe precision and consistency of determining ΔSVI with NiCOM™ after PLR may have clinical implication if ΔSVI > 10% is the absolute cutoff to determine fluid responsiveness.

Abstract P177: The Dissociation of Heart Rate and Blood Pressure Masks the Regulatory Role of Heart Rate in Systemic Hemodynamics

Blood pressure (BP) and heart rate (HR) are independent cardiovascular risk factors but there is little information about interactions among HR, BP, and systemic hemodynamics throughout the day. We performed 24-hour ambulatory pulse wave analysis (Mobil-O-Graph, IEM, Stolberg, DE) with measurements at 20 minute intervals. Variables measured were: systolic and diastolic BP (SBP and DBP), HR, oscillometric pulse wave velocity (oPWV), stroke volume index (SVI), and total vascular resistance index (TVRI). We also performed regression analyses within-subjects to determine the slopes of the SVI-HR and TVRI-HR relationships within individuals and for the group. We studied 89 individuals (mean age 61 years, weight 84 kg, BP 138/82 mm Hg (38 normal or controlled BP, 51 uncontrolled BP), resting HR 69 beats/min (bpm), 36% non-white, 64% female); 24-hour mean HR was not correlated with corresponding SBP or DBP values (r= -0.013 and r= 0.154, pNS, respectively) and this dissociation persisted in corresponding day-time vs. night-time comparisons and subgroup stratification by BP control status, age, and gender. In contrast, 24-hour mean HR was strongly correlated with 24-hour mean cardiac index (r=0.629, p&lt;0.000) but strongly inversely related to mean 24-hour SVI and TVRI (r= -0.508 and r= -0.505, p&lt;0.000 each); each 10 beat/min change in mean HR was associated with a 2.3 mL/m 2 (6%) change in SVI and a corresponding 6% change in TVRI. Analysis of individual 24-hour studies also revealed no correlations between HR and BP but the within-individual slopes and correlation coefficients between HR and SVI or TVRI were more variable; higher oPWV (which correlated with the SD of SBP, p=.01) was associated with a lesser sensitivity of SVI to HR change and a greater sensitivity of TVRI to HR change (p&lt;0.001 each) independent of age, gender, or BP. We conclude that BP is normally independent of HR, which plays a hidden but important regulatory role in the underlying systemic hemodynamics between and within individuals. The clinical impact of differential sensitivity of systemic hemodynamics to HR change is not established but people with stiffer arteries display diminished SVI sensitivity and greater TVRI sensitivity to HR change, which may contribute to their greater SBP variability.

The ultrasonic cardiac output monitor (USCOM) as a tool in evaluating fluid responsiveness in pediatric patients underwent emergency surgery

Background: Assessment fluid adequacy in pediatric patients underwent surgery is a challenge for anesthesiologists. Hemodynamic parameters used as fluid monitoring sometimes don't accurately provide valid information. Ultrasonic Cardiac Output Monitor (USCOM) is one of the non-invasive methods that are easy to operate and may provide various hemodynamic parameters monitoring information. Objective: Analyze the effectiveness of Stroke Volume Variation (SVV) and Stroke Volume Index (SVI) by using USCOM in assessing fluid responsiveness in preoperative pediatric patients who underwent emergency surgeries. Method: This study was conducted on 16 pediatric patients underwent emergency surgeries. Before general anesthesia is given, blood pressure, mean arterial pressure, heart rate, cardiac index, SVV, SVI were recorded before and after administration of 10 mL/kg of fluid given within 20 minutes Results: 10 subjects responded with SVV and SVI changes of more than 10% compared to 6 non-responders. SVV changes between responders and non-responders were 31.5±1.58 and 7.5±1.04, respectively. SVV percentage changes between responders and non-responders were 38.04±0.47 and 5.24±4.89, respectively. Conclusion: SVV and SVI recorded by USCOM showed significant fluid responsiveness changes in pediatric patients underwent emergency surgeries in 62.5% of the subjects.