Stroke Volume Variation Research Articles

Fluid responsiveness in pediatrics: an unsolved challenge

Predicting fluid responsiveness is a major challenge in the pediatric population as vascular and pulmonary compliance differ from the adults. However it is a crucial thing to avoid the harmful fluid overload. We count on different variables to identify responders being the dynamic parameters the ones with more evidence, specially the Respiratory Variation In Aortic Blood Flow Velocity based on echocardiography. Other variables rely on the arterial waveform, like Pulse Pressure Variation or Stroke Volume Variation seem to have limitations but new tests like VTC are arriving to overcome their drawbacks. We review the actual evidence regarding fluid responsiveness prediction in children and the anatomic and physiologic peculiarities of children that explain why they do not respond like adults and why we should study them in particular.

Comparison of pulse pressure and stroke volume variations measured by three monitors in high-risk surgical patients

IntroductionDynamic indices of fluid responsiveness (FR) such as pulse pressure variation (PPV) and stroke volume variation (SVV) differ among hemodynamic monitors, which use proprietary algorithms, and vary even over a short period of time. We aimed to compare the baseline values, fluctuation and predictive value for FR of PPV and SVV measured by three minimally invasive monitors. Patients and methodsTwenty patients undergoing high-risk abdominal surgery were included and 45 fluid challenges were analysed. The patients were simultaneously monitored using Carescape B650, LiDCO Rapid and FloTrac/Vigileo system. Cardiac output (CO), PPV and SVV were recorded before and after the fluid challenge of 500ml of balanced crystalloid solution. An increase in CO ≥ 15 % defined fluid responders. Concurrently recorded arterial waveform was used for offline calculation of PPV. ResultsMean baseline values of the indices ranged between 8.6% and 13.4%. LiDCO showed higher fluctuation of indices compared to the other monitors. Area under the receiver operating characteristic curve (AUROC) ranged from 0.71 to 0.76 with optimal cut-off value between 7.5% and 13.9%. AUROC increased for all indices when FR was defined as an increase in stroke volume. Furthermore, a decrease in PPV or SVV after fluid challenge (ΔPPV, ΔSVV) proved a better marker of FR (AUROC 0.82 – 0.93) than baseline values with a uniform threshold of approximately -3%. ConclusionsAlthough a significant range of baselines variations and optimal cut-off values was observed, the predictive value of PPV and SVV from all the monitors was only moderate and comparable. Nevertheless, ΔPPV and ΔSVV appear to be a reliable and device-independent markers of FR.

Evaluation of a Physiologic-Driven Closed-Loop Resuscitation Algorithm in an Animal Model of Hemorrhagic Shock.

Appropriate resuscitation from hemorrhagic shock is critical to restore tissue perfusion and to avoid over-resuscitation. The objective of this study was to test the ability of a closed-loop diagnosis and resuscitation algorithm called resuscitation from shock using functional hemodynamic monitoring using invasive monitoring (ReFit1) and minimally invasive monitoring (ReFit2) to identify, treat, and stabilize a porcine model of severe hemorrhagic shock. We created a ReFit algorithm using dynamic hemodynamic parameters of pulse pressure variation (PPV), stroke volume variation (SVV), dynamic arterial elastance (Eadyn = PPV/SVV), driven by mean arterial pressure (MAP), mixed venous oxygen saturation, and heart rate targets to define the need for fluids, vasopressors, and inotropes. University-based animal laboratory. Twenty-seven female pigs. Anesthetized, intubated, and ventilated (8 mL/kg) pigs were bled at 10 mL/min until a MAP of less than 40 mm Hg, held for 30 minutes, then resuscitated. The ReFit algorithm used the above dynamic parameters to drive computer-controlled infusion pumps to deliver blood, lactated Ringer's solution, norepinephrine, and in ReFit1 dobutamine. In four animals, after initial resuscitation from hemorrhagic shock, the ability of the ReFit1 algorithm to treat acute air embolism-induced pulmonary hypertension and right heart failure was also tested. In 10 ReFit1 and 17 ReFit2 animals, the time to stabilization from shock was not dissimilar to open controlled resuscitation performed by an expert physician (52 ± 12, 50 ± 13, and 60 ± 15 min, respectively) with similar amounts of fluids and norepinephrine needed. In four ReFit1 animals after initial stabilization, the algorithm successfully resuscitated the animals after inducing an acute air embolism right heart failure, with all animals recovering stability within 30 minutes. Our physiologically based functional hemodynamic monitoring-centered closed-loop resuscitation system can effectively diagnose and treat cardiovascular shock due to hemorrhage and air embolism.

Comparison of Hemodynamic Effects of Remimazolam and Midazolam During Anesthesia Induction in Patients Undergoing Cardiovascular Surgery: A Single-Center Retrospective and Exploratory Study.

Patients undergoing cardiovascular surgery may experience hemodynamic instability during the induction of general anesthesia, and anesthetic agents with minimal hemodynamic effects should be administered. Midazolam, a classic benzodiazepine anesthetic, is known to have relatively weak circulatory depression during anesthesia induction compared to other sedatives. On the other hand, remimazolam, a newly approved short-acting benzodiazepine anesthetic, is expected to have fewer circulatory depressant effects. However, comparisons between remimazolam and midazolam regarding circulatory depression during anesthesia induction have not been adequately studied. This study aims to compare the hemodynamic effects of remimazolam and midazolam during anesthesia induction in patients undergoing cardiovascular surgery. In this single-center retrospective and exploratory study, adults undergoing cardiovascular surgery under general anesthesia were divided into the remimazolam group (R group) and midazolam group (M group). Remimazolam 0.06 mg/kg (R group) or midazolam 0.03 mg/kg (M group) was administered during induction of general anesthesia. Both groups received remifentanil 1 μg/kg/min as analgesia. During anesthesia induction, additional sedatives (remimazolam or midazolam, respectively) were administered as needed to maintain the bispectral index (BIS) below 60. The primary endpoints were the following hemodynamic parameters: mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), stroke volume index (SVI), systemic vascular resistance index (SVRI), and stroke volume variation (SVV). Measurements were taken before the induction of anesthesia, one and three minutes after rocuronium administration, and one, three, five, and 10 minutes after tracheal intubation. Secondary endpoints included the number of patients requiring vasopressors and vasopressor dosage, time to fall asleep, and BIS values. All values are expressed as the median (interquartile range). Continuous variables were compared using the Mann-Whitney U test. Statistically significant differences were set at p-values <0.05. Forty patients (20 in each group) were included in the final analysis. The doses of remimazolam and midazolam until sleep onset were 0.058 (0.053, 0.066) mg/kg in the R group and 0.035 (0.03, 0.045) mg/kg in the M group. The MAP at five minutes and 10 minutes after tracheal intubation was significantly higher in the R group than in the M group (p=0.031 and p=0.004, respectively). The HR, CI, SVI, SVRI, and SVV were not significantly different between the two groups at any of the measurement points. The number of patients requiring vasopressors and vasopressor dosage were not statistically significant between the two groups. The time to fall asleep was 124 seconds (90, 142) in the R group and 146 seconds (130, 167) in the M group, with a significant difference (p=0.01). The BIS values during anesthesia induction were not significantly different between the two groups. Remimazolam had fewer hemodynamic effects than midazolam, even with relatively high doses and an earlier sleep onset. In terms of hemodynamic stability, remimazolam may be beneficial during anesthetic induction; however, further research is needed to confirm its efficacy.

Small changes in the transducer position cause a systematic change in cardiac output readings: implications for clinical practice.

To systematically evaluate the effect of small changes in transducer position on key hemodynamic variables including CO generated by 4th generation FloTrac software. After cardiac surgery, cardiac output, mean arterial pressure, systemic vascular resistance, and stroke volume variation were measured with 4 generation Flotrac software. The transducer position was randomly placed at the midaxillary plane, 4cm higher than the midaxillary plane or 4cm lower than the midaxillary plane. Averages of three measurements were used. Data was available from 20 patients. Cardiac output increased from 4.59L/min (± 0.92) to 4.78L/min (± 0.99) with the transducer position at the midaxillary plane to 4cm higher than the midaxillary plane, and cardiac output decreased to 4.43L/min (± 0.90) with the transducer 4cm lower than midaxillary plane (P < 0.001). On the relative scale, CO increased 4.1% (95% CI 3.1-5.0) when comparing the higher transducer level with the midaxillary plane position, and CO decreased 3.4% (95% CI 2.4-4.4) when comparing the midaxillary plane position with the lower transducer level, correspondiong to changes in CO of ≈ 1% per 1cm change in transducer position. Mean arterial pressure and systemic vascular resistance both changed significantly with transducer position (both P < 0.001), whereas no statistically or clinically significant effect was seen on stroke volume variation (P = 0.98). A four-centimeter change in vertical transducer position induced clinically significant changes in cardiac output measurements by 4th generation FloTrac software. Definitions of optimal cardiac output in goal-directed therapy algorithms require meticulous transducer adjustment and can only be used in the reference patient position.

Bedside imaging

Sonography, in particular echocardiography, is essential in the assessment of volume status and hemodynamics in critically ill patients. Examination of the left ventricle, in addition to assessing ventricular function, provides valuable information, including the "kissing papillary muscle sign," which may indicate fluid responsiveness. Examination of the right ventricle is also important because it is sensitive to both volume and pressure overload. Assessment of diastolic function and measurement of inferior vena cava width and variability provide clues to left and right ventricular preload, respectively. Measurement of stroke volume and cardiac output allows further assessment of hemodynamics and also permits determination of stroke volume variability.

Association Between Arterial Pulse Waveform Analysis and Mortality in Patients With Septic Shock: A Retrospective Cohort Study Using Japanese Diagnosis Procedure Combination Data.

Purpose: Specialized pressure transducers for arterial pulse waveform analysis (S-APWA) devices are dedicated kits connected to an arterial pressure catheter that monitors hemodynamic parameters, such as cardiac output, pulse pressure variation, and stroke volume variation, less invasively. While the association between the use of S-APWA devices and clinical outcomes in perioperative patients has been previously evaluated, its assessment in patients with septic shock remains inadequate. Materials and Methods: This retrospective cohort study utilized a nationwide Diagnosis Procedure Combination database in Japan. Adult patients with septic shock admitted to the intensive care unit (ICU) with arterial pressure catheter placement on the admission day from August 2012 to February 2021 were included. Hospitalizations meeting the eligibility criteria were categorized into groups based on S-APWA device usage. The primary outcome, evaluated using Cox regression analysis, was 30-day all-cause mortality in the propensity score overlap-weighted population. Secondary outcomes included in-hospital mortality, ICU duration, and overall hospital stay. Results: Among 5130 eligible hospitalizations, 643 were in the S-APWA group and 4487 were in the conventional pressure transducer group. Cox regression analysis within the propensity score overlap-weighted population showed no significant difference in 30-day mortality (adjusted hazard ratio: 0.94; 95% confidence interval: 0.9-1.38; P = .58). Logistic regression analysis indicated no significant differences in the in-hospital mortality. While the S-APWA group had prolonged ICU stays, no significant difference in the overall hospital stay was observed according to linear regression analyses. Conclusions: Our study found no significant association between S-APWA use and 30-day mortality in patients with septic shock. These findings offer insights into optimizing monitoring systems in ICUs.

Functional hemodynamic monitoring

Critically ill patients in the intensive care unit require intensified monitoring to control the treatment with volume and/or vasoactive substances. What role does functional hemodynamic monitoring play in controlling treatment and what techniques are used to manage this? Review of the current literature. Precise knowledge of the physiology of the cardiovascular system as well as the pathophysiology of individual clinical pictures and the possibilities of invasive and noninvasive monitoring are the prerequisites for the indications, implementation and interpretation of functional hemodynamic monitoring. An understanding of the heart-lung interaction and the influence of invasive ventilation on the volumetric target parameters, such as stroke volume variation, systolic pressure variation and pulse pressure variation as well as sonography of the inferior vena cava are indispensable prerequisites for the question of volume responsiveness. Other maneuvers, such as the passive leg raising test, can be very helpful when deciding on volume administration in everyday clinical practice. Static parameters such as central venous pressure generally play no role and if any only a subordinate one.

Impact of staged goal-directed fluid therapy on postoperative pulmonary complications in patients undergoing McKeown esophagectomy: a randomized controlled trial

BackgroundOur aim was to evaluate the influence of staged goal directed therapy (GDT) on postoperative pulmonary complications (PPCs), intraoperative hemodynamics and oxygenation in patients undergoing Mckeown esophagectomy.MethodsPatients were randomly divided into three groups, staged GDT group (group A, n = 56): stroke volume variation (SVV) was set at 8–10% during the one lung ventilation (OLV) stage and 8–12% during the two lung ventilation (TLV) stage, GDT group (group B, n = 56): received GDT with a target SVV of 8–12% During the entire surgical procedure, and control group (group C, n = 56): conventional fluid therapy was administered by mean arterial pressure (MAP), central venous pressure (CVP), and urine volume. The primary outcome was the incidence of postoperative pulmonary complications within Postoperative days (POD) 7. The secondary outcomes were postoperative lung ultrasound (LUS) B-lines artefacts (BLA) scoring, incidence of other complications, the length of hospital stay, intraoperative hemodynamic and oxygenation indicators included mean arterial pressure (MAP), heart rate (HR), cardiac index (CI), cardiac output (CO), oxygenation index (OI), respiratory indices (RI), alveolar-arterial oxygen difference (Aa-DO2).ResultsPatients in group A and group B had a lower incidence of PPCs (7/56 vs. 17/56 and 9/56 vs. 17/56, p < 0.05), and a fewer B-lines score on postoperative ultrasound (4.61 ± 0.51 vs. 6.15 ± 0.74 and 4.75 ± 0.62 vs. 6.15 ± 0.74, p < 0.05) compared to group C. The CI, CO, MAP, and OI were higher in group A compared to group B and group C in the stage of thoracic operation. During the abdominal operation stage, patients in group A and group B had a better hemodynamic and oxygenation indicators than group C.ConclusionsIn comparison to conventional fluid therapy, intraoperative staged GDT can significantly reduce the incidence of postoperative pulmonary complications in patients undergoing McKeown esophagectomy, facilitating patient recovery. Compared to GDT, it can improve intraoperative oxygenation and stabilize intraoperative hemodynamics in patients.Trial registrationThis study was registered in the Chinese Clinical Trial Registry on 24/11/2021 (ChiCTR2100053598).

Comparison of two different preload targets of stroke volume variation during kidney transplantation: a randomised controlled trial.

Maintaining adequate preload during kidney transplantation (KT) is important for graft function. We evaluated whether a high or low normal target for a dynamic preload index of stroke volume variation (SVV) would impact graft function during living donor KT. We compared haemodynamic management algorithms using two different targets of SVV: SVV6% group (n = 30) versus SVV12% group (n = 30). Crystalloids were administered to achieve SVV less than the assigned target. Neutrophil gelatinase-associated lipocalin (NGAL) level at the end of surgery was compared. We also compared the incidence of delayed graft function (DGF), daily serum creatinine level and glomerular filtration rate (GFR) until 2 weeks postoperatively. The total amount of crystalloids administered was significantly different between the SVV6% and SVV12% groups (median [interquartile range] 2,250 [1,700-3,600] vs. 1,350 [1,050-1,900], P < 0.001). There was no significant difference in NGAL level at the end of the operation between the SVV6% and SVV12% groups (395 [234-560] vs. 518 [346-654], P = 0.115). The incidence of DGF was not significantly different, and there was no significant difference in the postoperative serum creatinine levels or GFR between the groups. Our randomised trial demonstrated that an SVV target of either 6% or 12% could be adequate as a preload management target for postoperative graft function during living donor KT. However, given the low incidence of DGF in living donor KT and type II error, our study should be interpreted carefully and further studies for deceased donor KT are required.

Assessment of fluid responsiveness after tidal volume challenge in renal transplant recipients: a nonrandomized prospective interventional study.

When applying lung-protective ventilation, fluid responsiveness cannot be predicted by pulse pressure variation (PPV) or stroke volume variation (SVV). Functional hemodynamic testing may help address this limitation. This study examined whether changes in dynamic indices such as PPV and SVV, induced by tidal volume challenge (TVC), can reliably predict fluid responsiveness in patients undergoing renal transplantation who receive lung-protective ventilation. This nonrandomized interventional study included renal transplant recipients with end-stage renal disease. Patients received ventilation with a 6 mL/kg tidal volume (TV), and the FloTrac system was attached for continuous hemodynamic monitoring. Participants were classified as responders or nonresponders based on whether fluid challenge increased the stroke volume index by more than 10%. The analysis included 36 patients, of whom 19 (52.8%) were responders and 17 (47.2%) were nonresponders. Among responders, the mean ΔPPV6-8 (calculated as PPV at a TV of 8 mL/kg predicted body weight [PBW] minus that at 6 mL/kg PBW) was 3.32±0.75 and ΔSVV6-8 was 2.58±0.77, compared to 0.82±0.53 and 0.70±0.92 for nonresponders, respectively. ΔPPV6-8 exhibited an area under the curve (AUC) of 0.97 (95% confidence interval [CI], 0.93-1.00; P≤0.001), with an optimal cutoff value of 1.5, sensitivity of 94.7%, and specificity of 94.1%. ΔSVV6-8 displayed an AUC of 0.93 (95% CI, 0.84-1.00; P≤0.001) at the same cutoff value of 1.5, with a sensitivity of 94.7% and a specificity of 76.5%. TVC-induced changes in PPV and SVV are predictive of fluid responsiveness in renal transplant recipients who receive intraoperative lung-protective ventilation.

Predicting stroke volume variation using central venous pressure waveform: a deep learning approach

Objective. This study evaluated the predictive performance of a deep learning approach to predict stroke volume variation (SVV) from central venous pressure (CVP) waveforms.Approach. Long short-term memory (LSTM) and the feed-forward neural network were sequenced to predict SVV using CVP waveforms obtained from the VitalDB database, an open-source registry. The input for the LSTM consisted of 10 s CVP waveforms sampled at 2 s intervals throughout the anesthesia duration. Inputs of the feed-forward network were the outputs of LSTM and demographic data such as age, sex, weight, and height. The final output of the feed-forward network was the SVV. The performance of SVV predicted by the deep learning model was compared to SVV estimated derived from arterial pulse waveform analysis using a commercialized model, EV1000.Main results. The model hyperparameters consisted of 12 memory cells in the LSTM layer and 32 nodes in the hidden layer of the feed-forward network. A total of 224 cases comprising 1717 978 CVP waveforms and EV1000/SVV data were used to construct and test the deep learning models. The concordance correlation coefficient between estimated SVV from the deep learning model were 0.993 (95% confidence interval, 0.992-0.993) for SVV measured by EV1000.Significance. Using a deep learning approach, CVP waveforms can accurately approximate SVV values close to those estimated using commercial arterial pulse waveform analysis.

Intraoperative goal-directed hemodynamic therapy through fluid administration to optimize the stroke volume: A meta-analysis of randomized controlled trials

ObjectiveTo evaluate the clinical impact of optimizing stroke volume (SV) through fluid administration as part of goal-directed hemodynamic therapy (GDHT) in adult patients undergoing elective major abdominal surgery. MethodsThis systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered in the PROSPERO database in January 2024. The intervention was defined as intraoperative GDHT based on the optimization or maximization of SV through fluid challenges, or by using dynamic indices of fluid responsiveness, including stroke volume variation, pulse pressure variation, and plethysmography variation index compared to usual fluid management. The primary outcome was postoperative complications. Secondary outcome variables included postoperative acute kidney injury (AKI), length of stay (LOS), intraoperative fluid administration, and 30-day mortality. ResultsA total of 29 randomized controlled trials (RCTs) met the inclusion criteria. There were no significant differences in the incidence of postoperative complications (RR 0.89; 95% CI, 0.78–1.00), postoperative AKI (OR 0.97; (95% IC, 0.55–1.70), and mortality (OR 0.80; 95% CI, 0.50–1.29). GDHT was associated with a reduced LOS compared to usual care (SMD: −0.17 [−0.32; −0.03]). The subgroup in which hydroxyethyl starch was used for hemodynamic optimization was associated with fewer complications (RR 0.79; 95% CI, 0.65–0.94), whereas the subgroup of patients in whom crystalloids were used was associated with an increased risk of postoperative complications (RR 1.08; 95% CI, 1.04–1.12). ConclusionsIn adults undergoing major surgery, goal-directed hemodynamic therapy focused on fluid-based stroke volume optimization did not reduce postoperative morbidity and mortality.

Assessment of fluid responsiveness using pulse pressure variation, stroke volume variation, plethysmographic variability index, central venous pressure, and inferior vena cava variation in patients undergoing mechanical ventilation: a systematic review and meta-analysis

ImportanceManeuvers assessing fluid responsiveness before an intravascular volume expansion may limit useless fluid administration, which in turn may improve outcomes.ObjectiveTo describe maneuvers for assessing fluid responsiveness in mechanically ventilated patients.RegistrationThe protocol was registered at PROSPERO: CRD42019146781.Information sources and searchPubMed, EMBASE, CINAHL, SCOPUS, and Web of Science were search from inception to 08/08/2023.Study selection and data collectionProspective and intervention studies were selected.Statistical analysisData for each maneuver were reported individually and data from the five most employed maneuvers were aggregated. A traditional and a Bayesian meta-analysis approach were performed.ResultsA total of 69 studies, encompassing 3185 fluid challenges and 2711 patients were analyzed. The prevalence of fluid responsiveness was 49.9%. Pulse pressure variation (PPV) was studied in 40 studies, mean threshold with 95% confidence intervals (95% CI) = 11.5 (10.5–12.4)%, and area under the receiver operating characteristics curve (AUC) with 95% CI was 0.87 (0.84–0.90). Stroke volume variation (SVV) was studied in 24 studies, mean threshold with 95% CI = 12.1 (10.9–13.3)%, and AUC with 95% CI was 0.87 (0.84–0.91). The plethysmographic variability index (PVI) was studied in 17 studies, mean threshold = 13.8 (12.3–15.3)%, and AUC was 0.88 (0.82–0.94). Central venous pressure (CVP) was studied in 12 studies, mean threshold with 95% CI = 9.0 (7.7–10.1) mmHg, and AUC with 95% CI was 0.77 (0.69–0.87). Inferior vena cava variation (∆IVC) was studied in 8 studies, mean threshold = 15.4 (13.3–17.6)%, and AUC with 95% CI was 0.83 (0.78–0.89).ConclusionsFluid responsiveness can be reliably assessed in adult patients under mechanical ventilation. Among the five maneuvers compared in predicting fluid responsiveness, PPV, SVV, and PVI were superior to CVP and ∆IVC. However, there is no data supporting any of the above mentioned as being the best maneuver. Additionally, other well-established tests, such as the passive leg raising test, end-expiratory occlusion test, and tidal volume challenge, are also reliable.

Efficacy and safety of dynamic arterial elastance for weaning vasopressor support in septic shock patients: a randomised controlled trial protocol

IntroductionThe dynamic arterial elastance (EaDyn), calculated as pulse pressure variation divided by stroke volume variation, has been studied as a predictor of vasopressor weaning. However, its potential as a haemodynamic...

Transitions from Aerobic to Anaerobic Metabolism and Oxygen Debt during Elective Major and Emergency Non-Cardiac Surgery.

Intraoperative hemodynamic and metabolic optimization of both the high-risk surgical patients and critically ill patients remains challenging. Reductions in oxygen delivery or increases in oxygen consumption can initiate complex cellular processes precipitating oxygen debt (OXD). This study tested the hypothesis that intraoperative changes in sublingual microcirculatory flow reflect clinically relevant transitions from aerobic to anaerobic metabolism (TRANAM). We included patients undergoing elective major and emergency non-cardiac surgery. Macro- and microcirculatory variables, oxygen extraction, and transitions of metabolism were assessed in both cohorts. In the elective group, OXD was progressively increased over time, with an estimated 2.24 unit increase every 30 min (adjusted p < 0.001). Also, OXD was negatively correlated with central venous pressure (ρ = -0.247, adjusted p = 0.006) and positively correlated with stroke volume variation (ρ = 0.185, adjusted p = 0.041). However, it was not significantly correlated with sublingual microcirculation variables. In the emergency surgery group, OXD increased during the first two intraoperative hours and then gradually decreased until the end of surgery. In that cohort, OXD was positively correlated with diastolic arterial pressure (ρ = 0.338, adjpatients and the critically ill patients remains challengingsted p = 0.015). Also, OXD was negatively correlated with cardiac index (ρ = -0.352, adjusted p = 0.003), Consensus Proportion of Perfused Vessels (PPV) (ρ = -0.438, adjusted p < 0.001), and Consensus PPV (small) (ρ = -0.434, adjusted p < 0.001). TRANAM were evident in both the elective major and emergency non-cardiac surgery cohorts independent of underlying alterations in the sublingual microcirculation.

Stroke Volume and Stroke Volume Variation, but not Cardiac Index Is Associated With Survival of Majorly Burned Patients in Early Burn Shock.

Adequate fluid therapy is crucial to maintain organ function after burn trauma. Major burns lead to a systemic response with fluid loss and cardiac dysfunction. To guide fluid therapy, measurement of cardiac pre- and afterload is helpful. Whereas cardiac function is usually measured after admission to intensive care unit (ICU), in this study, hemodynamic monitoring was performed directly after arrival at hospital. We conducted a prospective cohort study with inclusion of 19 patients (male/female 13/6, 55 ± 18 years, mean total body surface area 36 ± 19%). Arterial waveform analysis (PulsioFlexProAqt®, Getinge) was implemented immediately after admission to hospital to measure cardiac pre- and afterload and to guide resuscitation therapy. Cardiac parameters 3.75 (2.67-6.0) h after trauma were normal regarding cardiac index (3.45 ± 0.82) L/min/m², systemic vascular resistance index (1749 ± 533) dyn sec/cm5 m2, and stroke volume (SV; 80 ± 20) mL. Stroke volume variation (SVV) was increased (21 ± 7) % and associated with mortality (mean SVV survivors vs nonsurvivors 18.92 (±6.37) % vs 27.6 (±5.68) %, P = .017). Stroke volume was associated with mortality at the time of ICU-admission (mean SV survivors vs nonsurvivors 90 (±20) mL vs 50 (±0) mL, P = .004). Changes after volume challenge were significant for SVV (24 ± 9 vs19 ± 8%, P = .01) and SV (68 ± 24 vs 76 ± 26 mL, P = .03). We described association of SVV and SV with survival of severely burned patients in an observational study. This indicates high valence of those parameters in the early postburn period. The use of an autocalibrated device enables a very early monitoring of parameters relevant to burn shock survival.

A retrospective study of the effects of a vasopressor bolus on systolic slope (dP/dt) and dynamic arterial elastance (Eadyn)

BackgroundTo enhance the utility of functional hemodynamic monitoring, the variables systolic slope (dP/dt) and dynamic arterial elastance (Eadyn) are calculated by the Hypotension Prediction Index (HPI) Acumen® Software. This study was designed to characterize the effects of phenylephrine and ephedrine on dP/dt and Eadyn.MethodsThis was a retrospective, non-randomized analysis of data collected during two clinical studies. All patients required intra-operative controlled mechanical ventilation and had an indwelling radial artery catheter connected to an Acumen IQ sensor. Raw arterial pressure waveform data was downloaded from the patient monitor and all hemodynamic measurements were calculated off-line. The anesthetic record was reviewed for bolus administrations of either phenylephrine or ephedrine. Cardiovascular variables prior to drug administration were compared to those following vasopressor administrations. The primary outcome was the difference for dP/dt and Eadyn at baseline compared with the average after the bolus administration. All data sets demonstrated non-normal distributions so statistical analysis of paired and unpaired data followed the Wilcoxon matched pairs signed-rank test or Mann-Whitney U test, respectively.Results201 doses of phenylephrine and 100 doses of ephedrine were analyzed. All data sets are reported as median [95% CI]. Mean arterial pressure (MAP) increased from 62 [54,68] to 78 [76,80] mmHg following phenylephrine and from 59 [55,62] to 80 [77,83] mmHg following ephedrine. Stroke volume and cardiac output both increased. Stroke volume variation and pulse pressure variation decreased. Both drugs produced significant increases in dP/dt, from 571 [531, 645] to 767 [733, 811] mmHg/sec for phenylephrine and from 537 [509, 596] to 848 [779, 930] mmHg/sec for ephedrine. No significant changes in Eadyn were observed.ConclusionBolus administration of phenylephrine or ephedrine increases dP/dt but does not change Eadyn. dP/dt demonstrates potential for predicting the inotropic response to phenylephrine or ephedrine, providing guidance for the most efficacious vasopressor when treating hypotension.Trial registrationData was collected from two protocols. The first was deemed to not require written, informed consent by the Institutional Review Board (IRB). The second was IRB-approved (Effect of Diastolic Dysfunction on Dynamic Cardiac Monitors) and registered on ClinicalTrials.gov (NCT04177225).

Intraoperative goal-directed fluid management and postoperative brain edema in patients having high-grade gliomas resections: a randomized trial.

Patients with high-grade gliomas often have severe brain edema. Goal-directed fluid management protects neurological function, but whether reduces postoperative brain edema remains unknown. Patients having elective resection of supratentorial malignant gliomas were randomly assigned to goal-directed versus routine fluid management. Patients assigned to goal-directed management group were given 3mL kg-1 hydroxyethyl starch solution when stroke volume variation exceeded 15% for 5 minutes. Fluid was managed per routine by attending anesthesiologists in reference patients. The primary outcome was cerebral edema volume after surgery as assessed by computerized tomography. A total of 480 eligible patients were randomly assigned to the goal-directed (n = 240) or the routine fluid management group (n = 240). The amounts of crystalloid (5.4 vs. 7.0ml kg-1 hour-1, P < 0.001), colloid (1.1 vs. 1.7ml kg-1 hour-1, P < 0.001), and overall fluid balance (0.3 vs. 1.9ml kg-1 hour-1, P < 0.001) were significantly lower in goal-directed fluid management. There was no significant difference in postoperative brain edema volume between groups (36.0cm3 vs. 38.9cm3, mean difference: 0.18cm3, 95% CI: -5.7 to 5.9). Goal-directed patients had lower intraoperative dural tension (risk ratio: 0.63, 95% CI: 0.50 to 0.80, P < 0.001). There was no significant difference in Karnofsky Performance Status between the two groups at 30 days after surgery. Goal-directed fluid therapy substantially reduced intravenous fluid volumes, but did not reduce postoperative brain edema in patients having brain tumor resections.

Analysis of hemodynamics and impedance using bioelectrical impedance analysis in hypovolemic shock-induced swine model

To treat hypovolemic shock, fluid infusion or blood transfusion is essential to address insufficient volume. Much controversy surrounds resuscitation in hypovolemic shock. We aimed to identify the ideal fluid combination for treating hypovolemic shock-induced swine model, analyzing bioelectrical impedance and hemodynamics. Fifteen female three-way crossbred pigs were divided into three different groups. The three resuscitation fluids were (1) balanced crystalloid, (2) balanced crystalloid + 5% dextrose water, and (3) balanced crystalloid + 20% albumin. The experiment was divided into three phases and conducted sequentially: (1) controlled hemorrhage (1 L bleeding, 60 min), (2) resuscitation phase 1 (1 L fluid infusion, 60 min), and (3) resuscitation phase 2 (1 L fluid infusion, 60 min). Bioelectrical impedance analysis was implemented with a segmental multifrequency bioelectrical impedance analyzer. A total of 61 impedance measurements were assessed for each pig at six different frequencies in five segments of the pig. Pulse rate (PR), mean arterial pressure (MAP), stroke volume (SV), and stroke volume variation (SVV) were measured using a minimally invasive hemodynamic monitoring device. The three-dimensional graph showed a curved pattern when infused with 1 L of balanced crystalloid + 1 L of 5% dextrose water and 1.6 L of balanced crystalloid + 400 ml of 20% albumin. The 1M impedance increased in all groups during the controlled hemorrhage, and continuously decreased from fluid infusion to the end of the experiment. Only balanced crystalloid + 20% albumin significantly restored MAP and SV to the same level as the start of the experiment after the end of fluid infusion. There were no significant differences in MAP and SV from the time of recovery to the initial value of 1M impedance to the end of fluid infusion in all groups. The change and the recovery of hemodynamic indices such as MAP and SV coincide with the change and the recovery of 1M impedance. Using balanced crystalloid mixed with 20% albumin in hypovolemic shock-induced swine model may be helpful in securing hemodynamic stability, compared with balanced crystalloid single administration.