Changes In Stroke Volume Variation Research Articles

Plethysmography Variability Index and Stroke Volume Variation Changes in Relation to Central Venous Pressure Changes During Living Related Donor Right Hepatotomy: A Diagnostic Test Accuracy.

During donor hepatectomy, we investigated (1) the Electrical Cardiometry associations and agreements between noninvasive plethysmography variability index and noninvasive stroke volume variation, (2) their association with central venous pressure, and (3) their ability to monitor intraoperative changes and discriminate donors with increased blood loss. A diagnostic test accuracy was applied among donors (American Society of Anesthesiologists classification I). Data were recorded at 10 minutes after anesthesia induction, hourly during dissection, after resection, and at end of surgery. Crystalloids were restricted during resection to reduce central venous pressure but were otherwise infused to maintain mean invasive arterial blood pressure >60 mm Hg and urine output >0.5 mL/kg/h. All 34 donors were related. Sons or daughters represented 58.8% (median age 26.0 years [interquartile range, 21.0-34.0]). Median values (with interquartile ranges) were anesthesia time, 7.5 hours (7.0-8.0); blood loss, 400 mL (400.0-500.0); infused acetated Ringer solution, 4000.0 mL (3500.0-4500.0); colloids, 250.0 mL (0-500.0); and urine output, 1.4 mL/kg/h (1.30-1.7). No blood products were transfused. Central venous pressure showed negligible negative correlations for both plethysmography variability index and stroke volume variation. Plethysmography variability index showed negligible correlation and poor agreement with stroke volume variation (P < .001, with intraclass correlation = 0.213 and a relatively wide bias; 95% CI, 0.03-0.37). All 3 methods reflected a state of normovolemia despite fluid restriction during resection and were unable to discriminate donors with increased blood loss (>400 mL). Plethysmography variability index and stroke volume variation showed negligible correlation and poor agreement with central venous pressure. Transfusion-free dissection was possible despite normovolemia, with median values of 8 mm Hg central venous pressure, 10% stroke volume variation, and 12% plethysmography variability index. Plethysmography variability index and stroke volume variation were unable to discriminate donors with increased blood loss.

Changes in stroke volume variation and cardiac index during open major bowel surgery.

Stroke volume variation (SVV) is a dynamic indicator of preload, which is a determinant of cardiac output. Aims: Aim of this study was to evaluate the relationship between changes in SVV and cardiac index (CI) in patients with normal left ventricular function undergoing major open abdominal surgery. Patients undergoing major open abdominal surgery were monitored continuously with FloTrac® to measure SVV and CI along with standard monitoring. Both SVV and CI were noted at baseline and every 10 min thereafter till the end of surgery and were observed for concurrence between the measurements. 1800 pairs of measurement of SVV and CI were obtained from 60 patients. Mean SVV and CI (of all patients) measured at different time points of measurement showed that as SVV increased with time, the CI dropped correspondingly. When individual readings of CI and SVV were plotted against each other, the scatter was found to be wide, reiterating the lack of agreement between the two parameters (R2 = 0.035). SVV >13% suggesting hypovolemia was found at 207 time points. Of these, 175 had a CI >2.5 L/min/m2 and only 32 patients had a CI <2.5 L/min/m2. SVV, a dynamic index of fluid responsiveness can be used to monitor patients expected to have large fluid shifts during major abdominal surgery. It is very specific and has a high negative predictive value. When SVV increases, CI is usually maintained. Since many factors affect SVV and CI, any increase in SVV >13%, must be correlated with other parameters before administration of the fluid challenge.

Predicting Fluid Responsiveness Using Change in Pulse Pressure Variation and Stroke Volume Variation after Tidal Volume Challenge in Postoperative Patients Receiving Lung Protective Ventilation

Background: Lung protective ventilation with low tidal volume (VT) is beneficial in patients with intermediate to high risk of post-operative pulmonary complications. However, during low VT ventilation, pulse pressure variation (PPV) and stroke volume variation (SVV) do not predict fluid responsiveness. Objective: To determine whether changes in PPV and SVV after transient increases in VT could predict fluid responsiveness. Materials and Methods: The authors recorded 20 measurements from 15 patients experiencing post-operative acute circulatory failure. The authors performed a VT challenge by transient increasing VT from 6 to 8 mL/kg (VT₆-₈), 8 to 10 mL/kg (VT₈-₁₀), and 6 to 10 mL/kg (VT₆-₁₀) of patients’ predicted body weight. The change in PPV (∆PPV) at VT₆-₈ (∆PPV₆-₈), VT₈-₁₀ (∆PPV₈-₁₀), VT₆-₁₀ (∆PPV₆-₁₀), and the change in SVV (∆SVV) at VT₆-₈ (∆SVV₆-₈), VT₈-₁₀ (∆SVV₈-₁₀), and VT₆-₁₀ (∆SVV₆-₁₀) were recorded. Patients were classified as fluid responders if there was an increase in stroke volume of more than 10% after a fluid bolus. Results: Following the VT challenge, ∆PPV and ∆SVV failed to predict fluid responsiveness, with areas under the receiver operating characteristic curves (with 95% confidence intervals) of 0.49 (0.23 to 0.74), 0.54 (0.29 to 0.79), 0.52 (0.28 to 0.77) for ∆PPV₆-₈, ∆PPV₈-₁₀, and ∆PPV₆-₁₀, and 0.55 (0.30 to 0.80), 0.55 (0.31 to 0.80), and 0.59 (0.34 to 0.84) for ∆SVV₆-₈, ∆SVV₈-₁₀, and ∆SVV₆-₁₀, respectively. Conclusion: Changes in PPV and SVV after the VT challenge did not predict fluid responsiveness in post-operative patients with low VT ventilation. Trial registration: Thai Clinical Trials Registry, TCTR 20190808003 Keywords: Pulse pressure variation, Stroke volume variation, Fluid responsiveness, Tidal volume challenge

Changes in Stroke Volume Variation Induced by Passive Leg Raising to Predict Fluid Responsiveness in Cardiac Surgical Patients With Protective Ventilation

Stroke volume variation (SVV) has been used to predict fluid responsiveness. The authors hypothesized the changes in SVV induced by passive leg raising (PLR) might be an indicator of fluid responsiveness in patients with protective ventilation after cardiac surgery. A prospective single-center observational study. A single cardiac surgery intensive care unit at a tertiary hospital. A total of 123 patients undergoing cardiac surgery with hemodynamic instability. Tidal volume was set between 6 and 8 mL/kg of ideal body weight. PLR maneuver, fluid challenge. SVV was continuously recorded using pulse contour analysis before and immediately after a PLR test and after fluid challenge (500 mL of colloid given over 30 min). Sixty-three (51.22%) patients responded to fluid challenge, in which PLR and fluid challenge significantly increased the SV and decreased the SVV. The decrease in SVV induced by PLR was correlated with the SV changes induced by fluid challenge. A 4% decrease in the SVV induced by PLR-discriminated responders to fluid challenge with an area under the curve of 0.90. The gray zone identified a range of SVV changes induced by PLR (between -3.94% and -2.91%) for which fluid responsiveness could not be predicted reliably. The gray zone included 15.45% of the patients. The SVV at baseline predicted fluid responsiveness with an area under the curve of 0.72. Changes in the SVV induced by PLR predicted fluid responsiveness in cardiac surgical patients with protective ventilation.

Complex effects of continuous vasopressor infusion on fluid responsiveness during liver resection

Fluid responsiveness is an important factor to consider for fluid volume loading during major surgery. The effect of continuous vasopressor infusion on fluid responsiveness during prolonged major surgery is a concern. We hypothesised that continuous vasopressor infusion during major surgery might not exert significant effects on changes in stroke volume variation (SVV) following fluid bolus infusion, and thereby on fluid responsiveness. Randomised controlled trial. University hospital from April 2014 to August 2016. Patients undergoing liver resection who were randomised to receive continuous intravenous infusion of phenylephrine (P group), norepinephrine (N group), or no vasopressor (C group) (n=17/group). Exclusion criteria were cardiac arrhythmia and severe cardiac, pulmonary or renal dysfunction. Patients received 4 ml kg fluid boluses of 6% hydroxyethyl starch solution when SVV was at least 12%. Vasopressors were administered continuously to maintain the systemic vascular resistance index at more than 1900 dyn s cm m. Cardiac index and SVV were measured using the FloTrac/Vigileo system (Version 4.00). The number of fluid boluses with fluid responsiveness (i.e. >15% increase in cardiac index) was compared between groups using multilevel logistic regression analysis. Numbers of fluid responsive boluses in the C, P and N groups were 12 (14%), 22 (34%) and 19 (27%), respectively. Odds ratios on fluid responsiveness for phenylephrine and norepinephrine compared with the control were 3.65 (97.5% confidence interval, 1.15 to 11.6; P = 0.012) and 2.56 (97.5% confidence interval, 0.82 to 8.00; P = 0.064), respectively. Decreases in SVV after fluid bolus infusion for the P and N groups were comparable with the C group (P = 0.23 and 0.53, respectively). Continuous administration of phenylephrine increased fluid responsiveness during liver resection, suggesting complex effects of continuous vasopressor infusion involving changes in cardiac preload and afterload. UMIN000011024.

The tidal volume challenge improves the reliability of dynamic preload indices during robot-assisted laparoscopic surgery in the Trendelenburg position with lung-protective ventilation

BackgroundThe reliability of pulse pressure variation (PPV) and stroke volume variation (SVV) is controversial under pneumoperitoneum. In addition, the usefulness of these indices is being called into question with the increasing adoption of lung-protective ventilation using low tidal volume (VT) in surgical patients. A recent study indicated that changes in PPV or SVV obtained by transiently increasing VT (VT challenge) accurately predicted fluid responsiveness even in critically ill patients receiving low VT. We evaluated whether the changes in PPV and SVV induced by a VT challenge predicted fluid responsiveness during pneumoperitoneum.MethodsWe performed an interventional prospective study in patients undergoing robot-assisted laparoscopic surgery in the Trendelenburg position under lung-protective ventilation. PPV, SVV, and the stroke volume index (SVI) were measured at a VT of 6 mL/kg and 3 min after increasing the VT to 8 mL/kg. The VT was reduced to 6 mL/kg, and measurements were performed before and 5 min after volume expansion (infusing 6% hydroxyethyl starch 6 ml/kg over 10 min). Fluid responsiveness was defined as ≥15% increase in the SVI.ResultsTwenty-four of the 38 patients enrolled in the study were responders. In the receiver operating characteristic curve analysis, an increase in PPV > 1% after the VT challenge showed excellent predictive capability for fluid responsiveness, with an area under the curve (AUC) of 0.95 [95% confidence interval (CI), 0.83–0.99, P < 0.0001; sensitivity 92%, specificity 86%]. An increase in SVV > 2% after the VT challenge predicted fluid responsiveness, but showed only fair predictive capability, with an AUC of 0.76 (95% CI, 0.60–0.89, P < 0.0006; sensitivity 46%, specificity 100%). The augmented values of PPV and SVV following VT challenge also showed the improved predictability of fluid responsiveness compared to PPV and SVV values (as measured by VT) of 6 ml/kg.ConclusionsThe change in PPV following the VT challenge has excellent reliability in predicting fluid responsiveness in our surgical population. The change in SVV and augmented values of PPV and SVV following this test are also reliable.Trial registrationThis trial was registered with Clinicaltrials.gov, NCT03467711, 10th March 2018.

Tidal volume challenge to predict fluid responsiveness in the operating room: An observational study.

Pulse pressure variation (PPV) and stroke volume variation (SVV) do not predict fluid responsiveness when using a protective ventilation strategy: the use of functional haemodynamic tests can be useful to overcome this limitation. We tested the use of a tidal volume challenge (VTC), during 6 ml kg [predicted body weight (PBW)] ventilation, and the end-expiratory occlusion test (EEOT) for prediction of fluid responsiveness. An interventional prospective study. Supine elective neurosurgical patients. The study protocol was, first, the initial EEOT test was performed during baseline 6 ml kg PBW ventilation; second, VTC was performed by increasing the VT up to 8 ml kg PBW and PPV and SVV changes were recorded after 1 min; third, a second EEOT was performed during 8 ml kg PBW ventilation; and VT was reduced back to 6 ml kg PBW and a third EEOT was performed. Finally, a 250 ml fluid challenge was administered over 10 min to identify fluid responders (increase in stroke volume index ≥10%). In the 40 patients analysed, PPV and SVV values at baseline and EEOT performed at 6 ml kg PBW did not predict fluid responsiveness. A 13.3% increase in PPV after VTC predicted fluid responsiveness with a sensitivity of 94.7% and a specificity of 76.1%, while a 12.1% increase in SVV after VTC predicted fluid responsiveness with a sensitivity of 78.9% and a specificity of 95.2%. After EEOT performed at 8 ml kg PBW, a 3.6% increase in cardiac index predicted fluid responsiveness with a sensitivity of 89.4% and a specificity of 85.7%, while a 4.7% increase in stroke volume index (SVI) with a sensitivity of 89.4% and a specificity of 85.7%. The changes in PPV and SVV obtained after VTC are reliable and comparable to the changes in CI and SVI obtained after EEOT performed at 8 ml kg PBW in predicting fluid responsiveness in neurosurgical patients. ACTRN12618000351213.

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.

Preemptive volume therapy to prevent hemodynamic changes caused by the beach chair position: hydroxyethyl starch 130/0.4 versus Ringer's acetate—a controlled randomized trial

Hemodynamic instability frequently occurs in beach chair positioning for surgery, putting patients at risk for cerebral adverse events. This study examined whether preoperative volume loading with crystalloids alone or with a crystalloid-colloid combination can prevent hemodynamic changes that may be causative for unfavorable neurologic outcomes. The study randomly assigned 43 adult patients undergoing shoulder surgery to 3 study groups. Each group received an infusion of 500 mL of Ringer's acetate between induction of anesthesia and being placed in the beach chair position. The crystalloid group received an additional bolus of 1000 mL Ringer's acetate. The hydroxyethyl starch group was administered an additional bolus of 500 mL of 6% hydroxyethyl starch 130/0.4. Hemodynamic monitoring was accomplished via an esophageal Doppler probe. Cerebral oxygen saturation was examined with near-infrared spectroscopy. Changes in stroke volume variation between the prone and beach chair positions were defined as the primary outcome parameter. Secondary outcomes were changes in cardiac output and cerebral oxygen saturation. The control group was prematurely stopped after enrollment of 4 patients because of adverse events. In the hydroxyethyl starch group, stroke volume variation remained constant during positioning maneuvers (P = .35), whereas a significant increase was observed in the Ringer's acetate group (P < .01; P = .014 for intergroup comparison). This was also valid for changes in cardiac output. Cerebral oxygen saturation significantly decreased in both groups. Preprocedural boluses of 500 mL of 6% hydroxyethyl starch 130/0.4 as well as 1000 mL of Ringer's acetate were efficient in preserving hemodynamic conditions during beach chair position.

Stroke volume variation and serum creatinine changes during abdominal aortic aneurysm surgery: a time-integrated analysis.

Patients undergoing abdominal aortic aneurysm (AAA) surgery with suprarenal clamping are at high risk for acute kidney injury (AKI) and major cardiac and cerebrovascular events (MACCE). We aimed to assess whether the stroke volume variation (SVV), a measure of hemodynamic instability, is associated with AKI in hypertensive patients undergoing elective AAA surgery with suprarenal clamping. In a cohort of 51 hypertensive patients, we performed serial measurements of SVV (n = 459) and serum creatinine (sCr) (n = 255). AKI was defined according to the KDIGO clinical practice guidelines. Data were analyzed by repeated-measures ANOVA and regression analysis of time-integrated changes of both SVV and sCr. AKI developed in 45% of patients (stage 1: 31%; stage 2: 10%; stage 3: 2%). The diuresis during surgery (beta - 0.29 Z-score 95% [CI -0.54, -0.05]; p = 0.02), clamp time (beta 0.29 Z-score [0.05-0.52]; p = 0.02), and time-integrated changes in SVV from baseline to 12h after surgery (beta 0.31 Z-score [0.03-0.60]; p = 0.03) were independent predictors of the time-integrated changes in sCr from baseline to 48h after the end of surgery. In a model adjusted for age and sex, patients with AKI had an increased risk for MACCE during a mean follow-up of 3.5 ± 1.1years (HR 5.53 [1.52-20.06]; p = 0.004). SVV increases progressively during and after AAA surgery in subjects who will develop AKI. The increase of SVV precedes and predicts the rise in sCr and is a good discriminator of the development of AKI. AKI is associated with an increased long-term risk for MACCE.

Fluid responsiveness prediction using Vigileo FloTrac measured cardiac output changes during passive leg raise test.

BackgroundPassive leg raising (PLR) is a so called self-volume challenge used to test for fluid responsiveness. Changes in cardiac output (CO) or stroke volume (SV) measured during PLR are used to predict the need for subsequent fluid loading. This requires a device that can measure CO changes rapidly. The Vigileo™ monitor, using third-generation software, allows continuous CO monitoring. The aim of this study was to compare changes in CO (measured with the Vigileo device) during a PLR manoeuvre to calculate the accuracy for predicting fluid responsiveness.MethodsThis is a prospective study in a 20-bedded mixed general critical care unit in a large non-university regional referral hospital. Fluid responders were defined as having an increase in CO of greater than 15 % following a fluid challenge. Patients meeting the criteria for circulatory shock with a Vigileo™ monitor (Vigileo™; FloTrac; Edwards™; Lifesciences, Irvine, CA, USA) already in situ, and assessed as requiring volume expansion by the clinical team based on clinical criteria, were included. All patients underwent a PLR manoeuvre followed by a fluid challenge.ResultsData was collected and analysed on stroke volume variation (SVV) at baseline and CO and SVV changes during the PLR manoeuvre and following a subsequent fluid challenge in 33 patients. The majority had septic shock. Patient characteristics, baseline haemodynamic variables and baseline vasoactive infusion requirements were similar between fluid responders (10 patients) and non-responders (23 patients). Peak increase in CO occurred within 120 s during the PLR in all cases. Using an optimal cut point of 9 % increase in CO during the PLR produced an area under the receiver operating characteristic curve of 0.85 (95 % CI 0.63 to 1.00) with a sensitivity of 80 % (95 % CI 44 to 96 %) and a specificity of 91 % (95 % CI 70 to 98 %).ConclusionsCO changes measured by the Vigileo™ monitor using third-generation software during a PLR test predict fluid responsiveness in mixed medical and surgical patients with vasopressor-dependent circulatory shock.Electronic supplementary materialThe online version of this article (doi:10.1186/s40560-016-0188-6) contains supplementary material, which is available to authorized users.

Effect of different positive end-expiratory pressure levels on stroke volume variations in patients with acute respiratory distress syndrome treated with mechanical ventilation

Objective To investigate the effect of different PEEP levels on stroke volume variation(SVV) in patients with acute respiratory distress syndrome(ARDS) treated with mechanical ventilation for predicting cardiac pre-load and the changes of hemodynamics. Methods Thirty critical patients with ARDS met the new criteria in 2012 set at European Berlin were enrolled in this study with measured values(MV) in EICU from September 2012 to October 2013.The changes in SVV and cardiac output(CO) monitored with Vigileo system were determined at different selected PEEE levels of 5, 7, 9, 11, 13, 15 mmHg.At the same time, MAP and CVP were measured. Results Variation of PEEP levels led to a significant changes in SVV, CO(P 0.05). The changes of CO showed a downtrend decline with the increase in PEEP levels.When PEEP was set at 13 mmHg and higher , the value of SVV denoted pre-load insufficiency. When PEEP was set at 11 mmHg or higher, cardiac output decreased.CVP could not predict the changes of pre-load. Conclusion Increase in PEEP levels can significantly reduce the cardiac pre-load.SVV can be a useful indicator of the changes in cardiac pre-load induced by high PEEP, suggesting fluid replacement necessary in time. Key words: Acute respiratory distress syndrome; Positive end-expiratory pressure; Stroke volume variations; Cardiac output; Central venous pressure

Relationship between Stroke Volume Variation and Stroke Volume during Major Abdominal Surgery Using Arterial Pulse Contour Analysis

Objective: Changes in stroke volume after fluid bolus infusion (i.e., fluid responsiveness) during major abdominal surgery is affected by painful stimuli, anesthetics and inconsistent increases in cardiac preload following each round of fluid infusion. This study aimed to assess the relationship between stroke volume variation (SVV) and stroke volume during major abdominal surgery using arterial pulse contour analysis by removing data of stroke volume affected by these factors. Methods: Eighty-three patients who underwent major abdominal surgery received 8 ml/kg boluses of either Ringer’s acetate or 6% hydroxyethyl starch 70/0.5 solution over the course of 30 minutes. Stroke volume index (SVI) and SVV were obtained using the FloTracTM/VigileoTM system (Version 3.02). Patients were classified according to values of absolute changes of SVV (ΔSVV, %) and relative changes of SVI (ΔSVI, %) following fluid bolus infusion. For each patient, ΔSVI was linearly regressed against SVV at different time points during the 60 minute period after initiation of bolus infusion. The relationship between SVV and ΔSVI was examined using the angle (radian) of the slope of ΔSVI against SVV. Results: Following fluid bolus infusion, SVI increased in 43% of patients due to an increase in cardiac preload (i.e., SVV decrease), and 33% of patients showed false SVI responses (ΔSVV 0). Angle values for SVV-ΔSVI in 50 patients were consistent in the SVV range of 9%-20% (i.e., 1.2); a 4% decrease in SVV resulted in a 10% increase in SVI. Conclusions: One-third of patients undergoing major abdominal surgery showed false responses for SVI following fluid bolus infusion. After excluding false responses for SVI, the relationship between SVV and ΔSVI during major abdominal surgery was almost linear in the SVV range of 9%-20%, suggesting that SVV changes following fluid bolus infusion significantly contribute to fluid responsiveness.

Assessment of Stroke Volume Variation Perioperatively by Using Arterial Pressure with Cardiac Output.

To observe the sensitivity of stroke volume variation (SVV) for assessing volume change during induction period of general anesthesia. Patients who underwent orthopaedic surgery under general anesthesia and mechanical ventilation were divided into two groups randomly. Patients in the group Ⅰwere subjected to progressive central hypovolemia and correction of hypovolemia sequentially; patients in the Group Ⅱ were exposed to hypervolemia alone. Each step was implemented after 5 minutes when the hemodynamics was stable. SVV and cardiac index (CI) were recorded, and Pearson's product-moment correlation was used to analyze correlation between SVV and CI. Forty patients were included in this study, 20 cases in each group. For group Ⅰ patients, SVV was increased significantly along with blood volume reduction, and changes in CI were negatively correlated with changes in SVV (r=-0.605, P<0.01); SVV decreased significantly along with correction of blood volume; changes in CI were negatively correlated with changes in SVV (r=-0.651, P<0.01). For group Ⅱ patients, along with blood volume increase, SVV did not change significantly; changes in CI revealed no significant correlation with changes in SVV (r=0.067, P>0.05). SVV is a useful indicator for hypovolemia, but not for hypervolemia.

The comparison of stroke volume variation with central venous pressure in predicting fluid responsiveness in septic patients with acute circulatory failure.

Purpose:The present study was designed to investigate the efficacy of stroke volume variation (SVV) in predicting fluid responsiveness and compare it to traditional measures of volume status assessment like central venous pressure (CVP).Methods:Forty-five mechanically ventilated patients in sepsis with acute circulatory failure. Patients were not included when they had atrial fibrillation, other severe arrhythmias, permanent pacemaker, or needed mechanical cardiac support. Furthermore, excluded were patients with hypoxemia and a CVP >12. Patients received volume expansion in the form of 500 ml of 6% hydroxyethyl starch.Results:The volume expansion-induced increase in cardiac index (CI) was >15% in 29 patients (labeled responders) and <15% in 16 patients (labeled nonresponders). Before volume expansion, SVV was higher in responders than in nonresponders. Receiver operating characteristic curves analysis showed that SVV was a more accurate indicator of fluid responsiveness than CVP. Before volume expansion, an SVV value of 13% allowed discrimination between responders and nonresponders with a sensitivity of 78% and a specificity of 89%. Volume expansion-induced changes in CI weakly and positively correlated with SVV before volume expansion. Volume expansion decreased SVV from 18.86 ± 4.35 to 7.57 ± 1.80 and volume expansion-induced changes in SVV moderately correlated with volume expansion-induced changes in CI.Conclusions:When predicting fluid responsiveness in mechanically ventilated patients in septic shock, SVV is more effective than CVP. Nevertheless, the overall correlation of baseline SVV with increases in CI remains poor. Trends in SVV, as reflected by decreases with volume replacement, seem to correlate much better with increases in CI.

Pneumoperitoneum affects stroke volume variation in humans.

Stroke volume variation (SVV) is affected by many factors. Although elevated intra-abdominal pressure and a pneumoperitoneum have been shown to increase SVV in animals, a recent human study showed that SVV did not change as a pneumoperitoneum was established. However, we considered the results of this study questionable, and we therefore attempted to study whether SVV changes both before and after pneumoperitoneums in humans. We performed a prospective observational study in 19 patients undergoing cholecystectomy or colectomy while on mechanical ventilation. Immediately before pneumoperitoneum, baseline registrations of variables were obtained (baseline I), which were measured every min for 5 min after the pneumoperitoneum was initiated. Immediately before the pneumoperitoneum was released, another baseline registration of variables was obtained (baseline II); these variables were then measured every min for 5 min. After the pneumoperitoneum was initiated, there were significant increases in SVV at the 2- to 5-min time points. After release of the pneumoperitoneum, there were significant decreases in SVV at the 1- to 5-min time points. A pneumoperitoneum increased SVV, which is similar to the findings of previous animal studies but is different from a previous clinical study. Upon release of the pneumoperitoneum, SVV decreased significantly, which is new information. SVV values must be estimated cautiously during a pneumoperitoneum.

Stroke volume variation fail to predict fluid responsiveness in patients undergoing pulmonary lobectomy with one-lung ventilation using thoracotomy

The purpose of this study was to investigate the ability of stroke volume variation (SVV) to predict fluid responsiveness in patients undergoing pulmonary lobectomy with one lung ventilation (OLV). Thirty patients intubated with double-lumen tube were scheduled for a pulmonary lobectomy requiring OLV for at least 1 hour under general anesthesia. Hemodynamic variables including heart rate, mean arterial pressure, cardiac index (CI), stroke volume index (SVI), central venous pressure (CVP) and SVV were measured before and after volume expansion (VE) (8 mL/kg of 6% hydroxyethyl starch). Fluid responsiveness was defined as an increase in CI ≥ 10% after VE. Of the 30 patients, 16 (53%) were responders and 14 (47%) were nonresponders to intravascular VE. There were significant increases of CI, SVI in responders after VE (p < 0.01), but there were no significant changes in SVV in responders and nonresponders (p > 0.05). The baseline value of SVV, CVP, CI and SVI did not correlate significantly with ΔCI (p > 0.05). The area under the Receiver Operating Characteristic (ROC) curve were 0.507 for SVV (95% confidence interval, 0.294-0.720) and 0.556 for CVP (95% confidence interval, 0.339-0.773), neither was able to predict fluid responsiveness with sufficient statistical power. SVV measured by the Vigileo-FloTrac system was not able to predict fluid responsiveness in patients undergoing pulmonary lobectomy with OLV after thoractomy.

Responsiveness of stroke volume variation and central venous pressure during acute normovolemic and hypervolemic hemodilution.

Stroke volume variation (SVV) is a robust indicator of fluid responsiveness during volume change. We compared the sensibility of SVV by Vigileo/Flotrac to central venous pressure (CVP) when volume changes in patients undergoing intraoperative acute normovolemic hemodilution (ANH) and acute hypervolemic hemodilution (AHH). Forty patients were randomly divided into an ANH group (n = 20) and an AHH group (n = 20). All patients received general anesthesia and were mechanically ventilated. Data were collected from 7 different time-points in the ANH group: baseline, after withdrawal of 5%, 10%, and 15% of the estimated blood volume (EBV) and after replacement with an equal volume of 6% hydroxyethyl starch 130/0.4 (HES) in 5% EBV increments to baseline. There were four time points in the AHH group: baseline, after 5%, 10%, and 15% expansion of the EBV with 6% HES. At each time-point, CVP, SVV and other hemodynamic parameters measurements were obtained. After removal of 10% and 15% EBV, SVV significantly increased from 10.9 ± 3.0 to 14.1 ± 3.4 and 10.9 ± 3.0 to 16.0 ± 3.3 (P < 0.01), and returned to a final value of 10.6 ± 3.4 after volume replacement. The CVP value was unchanged after removal and replacement of 15% of the EBV. There were no significant changes in SVV after 5%, 10% whereas there was a significant reduction after 15% (8.2 ± 1.7) expansion of the EBV compared with baseline (9.9 ± 1.8) (P = 0.033). However, there was a significant increase in CVP after 10% (10.3 ± 2.4), 15% (11.3 ± 2.2) expansion of the EBV compared with baseline (8.2 ± 2.7) (P < 0.01). SVV is a more sensitive parameter for volume than CVP during hypovolemia, on the contrary CVP is more sensitive than SVV during hypervolemia.

Applying Dynamic Parameters to Predict Hemodynamic Response to Volume Expansion in Spontaneously Breathing Patients with Septic Shock

To the Editor We read with great interest the article by Lanspa et al. (1), in which they demonstrate that both vena cava collapsibility index (VCCI) and stroke volume variation (SVV) may be used to “predict hemodynamic response” in “non–mechanically ventilated” patients. The authors are to be congratulated for doing novel research on spontaneously ventilating patients with septic shock. Unfortunately, there are a number of serious issues we would like to address relative to the study design and the authors’ conclusions that SVV can be used to reliably assess volume responsiveness in these patients when this is not supported by the data. Although the authors acknowledge a very small sample size (N = 14) and that their results lack external validation, their methodology is still weak. With a sample size this small, all statistical inferences should be nonparametric, and it appears that only some were. The main analysis was calculating three c-statistics (area under the receiver operating characteristic curve) for three independent variables: VCCI, SVV, and aortic blood velocity variation with the binary outcome of an increased cardiac index 15% or greater. The authors conclude that VCCI and SVV were predictive of outcome because their c-statistics were high (0.83 and 0.92, respectively). This is misleading because the 95% confidence intervals [CIs] were wide because of the sample size (0.58–1.00 and 0.73–1.00, respectively). The aortic blood velocity variation c-statistic was 0.67 (95% CI, 0.32–1.00). Had the authors compared the c-statistics among these three predictors, they would all be statistically similar as the confidence intervals all have substantial overlap. Thus, one may not conclude that any of the three predictors had better predictive (discriminatory) ability than the other two, and all three predictors’ c-statistics may only be in the 0.7 to 0.75 range, indicating modest discrimination as all three CIs overlapped those values. The conclusions from their positive and negative predictive value analysis in Table 3 are also similarly dubious because of the sample size. Furthermore, only one predictor (VCCI) had a borderline significant difference in medians by response (P = 0.04), with the others being nonsignificant, as seen in Table 1. A limitation not acknowledged is that the study results are all unadjusted for confounding. If we assume a regular r-r interval, for any specific preload condition, dynamic indices, such as SVV, will vary with a patient’s tidal volume (Vt) (2) and respiratory rate (RR) and any variability in RR. This means Vt and RR are confounders and need to be adjusted for via regression to determine the true relationship between SVV and hemodynamic response. Indeed, Kim and Pinsky (3) have shown that SVV varies with RR and that one must hold Vt constant if changes in SVV are to assess preload responsiveness. Furthermore, the ability of either PPV or SVV to predict preload responsiveness varies with Vt (4). To this point, De Backer et al. (5) have shown that a minimum of 8 mL/kg is required for positive-pressure ventilation to reliably predict volume responsiveness during mechanical ventilation. Although it is true that “dynamic fluctuations in thoracic pressure occur” regardless of ventilation mode, it is highly unlikely that these spontaneously breathing patients (ostensibly with near-normal tidal breaths yet all being different) had values near 8 to 10 mL/kg. Third, the authors decry the passive-leg-raise maneuver, although it reliably predicts volume responsiveness with a pooled area under the curve of 0.95 (6) and is independent of either ventilatory mode or cardiac rhythm. The authors contend that limitations of the passive leg raise include patient movement, the requirement of a device, and that it is affected by raised intra-abdominal pressure. Indeed, although SVV does not require patient movement, it most certainly requires a device and is affected by intra-abdominal pressure, as are all dynamic indices. (7) Lanspa et al. attempted to answer an important research question, and it is unfortunate that they could not obtain an adequately powered sample. Pilot studies such as this do not contribute in a meaningful way to our understanding of the hemodynamic response to fluid therapy and may even be harmful if their findings are not interpreted cautiously. This study is remindful of Ioannidis’ (8) first corollary, which states that “the smaller the studies conducted in a scientific field, the less likely the research findings are to be true.” No financial support was offered or obtained for the writing of this editorial letter. In addition, no NIH, Wellcome Trust, or Howard Hughes funding was used or obtained. J.A.B. and W.T.M. are on the speaker’s bureau for Edwards LifeSciences. B.H.N. has no potential conflicts of interest. Joshua A. Bloomstone Department Anesthesiology and Perioperative Medicine, Banner Thunderbird Medical Center Glendale, Arizona Brian H. Nathanson OptiStatim, LLC, Longmeadow William T. McGee Baystate Critical Care Medicine Springfield, Massachusetts

Do induced hypertension and hypotension affect stroke volume variation in man?

Study ObjectiveTo investigate changes in stroke volume variation (SVV) by both induced hypertension (pressor test) and hypotension (depressor test), and also by induced hypotensive anesthesia in patients with good cardiac function. DesignProspective, controlled clinical study. SettingUniversity hospital. Patients31 ASA physical status 1 and 2 patients, aged 39-62 years, who were scheduled for elective surgery. InterventionsWe conducted three studies: a pressor test study, a depressor test study, and an induced hypotensive anesthesia study. In the pressor test, patients received a bolus of phenylephrine 0.001 mg/kg to increase systolic arterial pressure (SAP) by 30% to 40% compared with baseline. In the depressor test, patients received a bolus of nitroglycerine 0.005 mg/kg to decrease SAP by 30% to 40% compared with baseline. In the induced hypotensive anesthesia test, patients received intravenous (IV) nitroglycerine continuously until mean arterial pressure (MAP) was reduced to 60-70 mmHg. MeasurementsWhen arterial pressure reached the target pressure for each study type, SVV and other parameters were recorded. Main ResultsInduced hypertension (pressor test) decreased SVV, while induced hypotension (depressor test) and induced hypotensive anesthesia increased SVV. ConclusionsSVV does not misinterpret preload dependency assessment of patients receiving medications to increase or to lower blood pressure.