Reliable Predictor Of Fluid Responsiveness Research Articles

Haemodynamic changes during radical nephrectomy with inferior vena cava thrombectomy: A pilot study.

Haemodynamic changes during radical nephrectomy with inferior vena cava thrombectomy: A pilot study.

Diagnostic accuracy of stroke volume variation for predicting fluid responsiveness in children undergoing cardiac surgery: A systematic review and meta-analysis.

Stroke volume variation appears to be reliable for predicting fluid responsiveness in adults, and its predictive value in pediatric patients has been recently reported. However, its predictive value in children undergoing cardiac surgery is unclear. A review and meta-analysis were performed on the diagnostic utility of stroke volume variation for predicting fluid responsiveness in children undergoing cardiac surgery. All relevant articles for prospective research assessing the value of stroke volume variation were searched in the Embase, MEDLINE (PubMed), and Cochrane databases through March 2020. The primary outcome was the accuracy of stroke volume variation for predicting fluid responsiveness in children. The combined data were analyzed by a meta-analysis. Publication quality was assessed using the QUADAS (quality assessment for studies of diagnostic accuracy, maximum score) standard guidelines. Six articles were included in the meta-analysis, following the search strategy. A total of 251 children were included from 6 prospective studies. Fluid therapy for all patients used crystalloids or colloids. The results of the analysis revealed a pooled diagnostic odds ratio of 8.23 (95% CI: 3.07-22.11), pooled sensitivity of 0.73 (95% CI: 0.64-0.80), and pooled specificity of 0.66 (95% CI: 0.58-0.74). Additionally, the overall area of the summary receiver operating characteristic curve was 0.78. There was significant moderate heterogeneity in these studies (p<.05, I2 =42.1%) due to thresholds. There was some heterogeneity due to thresholds in the included studies. An evaluation of stroke volume variation may represent a reliable predictor of fluid responsiveness in children undergoing cardiac surgery. After operative cardiac output optimization, the possible impact of goal-directed fluid treatment depending on stroke volume variation on the perioperative outcome in the children population should subsequently be assessed.

Role of Inferior Vena Cava Parameters as Predictors of Fluid Responsiveness in Pediatric Septic Shock: A Prospective Study

AbstractFluid resuscitation is the initial therapy for septic shock worldwide. Prediction of fluid responsiveness is essential for optimizing fluid administration. Only few pediatric studies have evaluated the role of inferior vena cava (IVC) as a reliable predictor of fluid responsiveness. The aim of this study was to evaluate the role of IVC parameters as predictors of fluid responsiveness in children (under the age of 5 years) having septic shock at different times from admission. A prospective observational study included 51 children having septic shock. It was conducted in the nine-bedded pediatric intensive care unit of a university hospital from January 1, 2018, to the August 31, 2018. Echocardiography was used to assess minimal and maximal IVC diameters and its distensibility index with simultaneous assessment of stroke volume (SV), at 1, 6, and 24 hours from admission. The decision to give fluid in these children was thereby based on the presence of at least one sign of inadequate tissue perfusion. SV was reassessed directly after administration of a fluid bolus of 10 mL/kg over 10 minutes. Fluid responsiveness was considered adequate when there was ≥ 10% increase in SV after fluid bolus. Minimal IVC diameter indexed to body surface area and its distensibility index can be predictors of fluid responsiveness at all times: 1 hour (area under curve [AUC] = 0.88; 95% confidence interval [CI] = 0.77–0.96), 6 hours (AUC = 0.86; 95% CI = 0.67–0.97), and 24 hours (AUC = 0.77; 95% CI = 0.6–0.95). IVC distensibility index can also predict fluid responsiveness at 1 hour (AUC= 0.87; 95% CI = 0.74–0.95), 6 hours (AUC = 0.86; 95% CI = 0.73–0.94), and 24 hours (AUC = 1; 95% CI = 0.77–1). The cutoff points of each parameter differed from time to time (contradicts with previous statement that says it is predictor at all times). The maximum IVC diameter could not predict fluid responsiveness at any time from admission. Minimal IVC diameter and its distensibility index were feasible noninvasive surrogates of fluid responsiveness in pediatric septic shock at different times from admission.

The effect of tidal volume on fluid responsiveness assessment using pulse pressure variations and velocity time integral variations in patients with septic shock

Introduction Expanding volume in septic shock can be a source of therapeutic dilemma. On one hand, the severity of the disease necessitates administration of fluids. On the other hand, it has now been clearly demonstrated that fluid overload has bad consequences. Many parameters were introduced to assess fluid responsiveness in patients with septic shock such as pulse pressure variations (PP%) and velocity time integral variations (VTI%). Objective The aim of this study was to determine whether the change in tidal volume introduced to patients with septic shock on mechanical ventilation would affect the values of PP% and VTI% of fluid responsiveness. Patients and methods In this prospective observational study, 60 mechanically ventilated patients with septic shock were enrolled. On admission, all patients received sedation and muscle relaxant to avoid any spontaneous breath. A fluid challenge in the form of 400 ml of normal saline 0.9% was given to all patients. However, before giving the normal saline to the patient, PP% and VTI% were measured when patient was given tidal volume 6 ml/kg and then when patient was given tidal volume 10 ml/kg. The same measures were repeated with the same tidal volumes, 1 min after giving the normal saline. Results A total of 31 patients were identified as fluid responders, whereas 29 patients were fluid nonresponders. In responders, the mean value of change of PP% with fluid challenge decreased significantly when increasing tidal volume from 6 to10 ml/kg, whereas the mean value of change of VTI% decreased insignificantly with tidal volume change. Conclusion PP% could be a reliable predictor of fluid responsiveness in patients with septic shock on a higher tidal volume ventilation, unlike VTI% which could be reliable at low tidal volume.

Prediction of fluid responsiveness in mechanically ventilated cardiac surgical patients: the performance of seven different functional hemodynamic parameters

BackgroundFunctional hemodynamic parameters such as stroke volume and pulse pressure variation (SVV and PPV) have been shown to be reliable predictors of fluid responsiveness in mechanically ventilated patients. Today, different minimally- and non-invasive hemodynamic monitoring systems measure functional hemodynamic parameters. Although some of these parameters are described by the same name, they differ in their measurement technique and thus may provide different results. We aimed to test the performance of seven functional hemodynamic parameters simultaneously in the same clinical setting.MethodsHemodynamic measurements were done in 30 cardiac surgery patients that were mechanically ventilated. Before and after a standardized intravenous fluid bolus, hemodynamics were measured by the following monitoring systems: PiCCOplus (SVVPiCCO, PPVPiCCO), LiDCOrapid (SVVLiDCO, PPVLiDCO), FloTrac (SVVFloTrac), Philips Intellivue (PPVPhilips) and Masimo pulse oximeter (pleth variability index, PVI). Prediction of fluid responsiveness was tested by calculation of receiver operating characteristic (ROC) curves including a gray zone approach and compared using Fisher’s Z-Test.ResultsFluid administration resulted in an increase in cardiac output, while all functional hemodynamic parameters decreased. A wide range of areas under the ROC-curve (AUC’s) was observed: AUC-SVVPiCCO = 0.91, AUC-PPVPiCCO = 0.88, AUC-SVVLiDCO = 0.78, AUC-PPVLiDCO = 0.89, AUC-SVVFloTrac = 0.87, AUC-PPVPhilips = 0.92 and AUC-PVI = 0.68. Optimal threshold values for prediction of fluid responsiveness ranged between 9.5 and 17.5%. Lowest threshold values were observed for SVVLiDCO, highest for PVI.ConclusionAll functional hemodynamic parameters tested except for PVI showed that their use allows a reliable identification of potential fluid responders. PVI however, may not be suitable after cardiac surgery to predict fluid responsiveness.Trial registrationNCT02571465, registered on October 7th, 2015 (retrospectively registered).

Positive end-expiratory pressure-induced increase in external jugular venous pressure does not predict fluid responsiveness in laparoscopic prostatectomy.

Dynamic change in central venous pressure (CVP) was associated with fluid responsiveness. External jugular venous pressure (EJVP) may reliably estimate CVP and have the advantages of being less invasive. We investigated whether increase in EJVP induced by positive end-expiratory pressure (PEEP) could be a reliable predictor of fluid responsiveness in patients undergoing robot-assisted laparoscopic prostatectomy (RALP). Fifty patients who underwent RALP with steep Trendelenburg position were enrolled. PEEP of 10cmH2O was applied for 5min and then 300ml of colloid was administered. EJVP, stroke volume variation (SVV), and cardiac index calculated by pulse contour method were measured before and after the PEEP challenge and colloid administration. Increase in cardiac index>10% was used to define the fluid responsiveness. Twenty-six patients were fluid responders. Neither the increase in EJVP after the initial PEEP nor SVV was significantly different between responders and non-responders. They were not significantly correlated with an increase in cardiac index. The areas under the receiver operating characteristic curve (AUC) of these two variables were not significantly greater than 0.5. However, a post hoc analysis revealed that AUC of a decrease in EJVP after removal of PEEP was significantly greater than 0.50. Our study results suggested that SVV and increase in EJVP after applying PEEP were not accurate predictors of fluid responsiveness during RALP. Further studies are required to find an adequate preload index in robot-assisted urologic surgery with steep Trendelenburg position.

Change in cardiac output during Trendelenburg maneuver is a reliable predictor of fluid responsiveness in patients with acute respiratory distress syndrome\xa0in the prone position under protective ventilation

BackgroundPredicting fluid responsiveness may help to avoid unnecessary fluid administration during acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate the diagnostic performance of the following methods to predict fluid responsiveness in ARDS patients under protective ventilation in the prone position: cardiac index variation during a Trendelenburg maneuver, cardiac index variation during an end-expiratory occlusion test, and both pulse pressure variation and change in pulse pressure variation from baseline during a tidal volume challenge by increasing tidal volume (VT) to 8 ml.kg-1.MethodsThis study is a prospective single-center study, performed in a medical intensive care unit, on ARDS patients with acute circulatory failure in the prone position. Patients were studied at baseline, during a 1-min shift to the Trendelenburg position, during a 15-s end-expiratory occlusion, during a 1-min increase in VT to 8 ml.kg-1, and after fluid administration. Fluid responsiveness was deemed present if cardiac index assessed by transpulmonary thermodilution increased by at least 15% after fluid administration.ResultsThere were 33 patients included, among whom 14 (42%) exhibited cardiac arrhythmia at baseline and 15 (45%) were deemed fluid-responsive. The area under the receiver operating characteristic (ROC) curve of the pulse contour-derived cardiac index change during the Trendelenburg maneuver and the end-expiratory occlusion test were 0.90 (95% CI, 0.80–1.00) and 0.65 (95% CI, 0.46–0.84), respectively. An increase in cardiac index ≥ 8% during the Trendelenburg maneuver enabled diagnosis of fluid responsiveness with sensitivity of 87% (95% CI, 67–100), and specificity of 89% (95% CI, 72–100). The area under the ROC curve of pulse pressure variation and change in pulse pressure variation during the tidal volume challenge were 0.52 (95% CI, 0.24–0.80) and 0.59 (95% CI, 0.31–0.88), respectively.ConclusionsChange in cardiac index during a Trendelenburg maneuver is a reliable test to predict fluid responsiveness in ARDS patients in the prone position, while neither change in cardiac index during end-expiratory occlusion, nor pulse pressure variation during a VT challenge reached acceptable predictive performance to predict fluid responsiveness in this setting.Trial registrationClinicalTrials.gov, NCT01965574. Registered on 16 October 2013. The trial was registered 6 days after inclusion of the first patient.

Respiratory variation in aortic blood peak velocity and caudal vena cava diameter can predict fluid responsiveness in anaesthetised and mechanically ventilated dogs

Background and M&MsDynamic preload indices, such as systolic pressure variation (SPV), aortic flow peak velocity variation (ΔVpeak) and distensibility index of the caudal vena cava (CVCDI), are reliable indices for predicting fluid responsiveness in humans. This study aimed to investigate the ability of these indices to predict fluid response in 24 healthy dogs undergoing general anaesthesia and mechanical ventilation. Aortic flow peak velocity variation (∆Vpeak), CVCDI, and SPV were calculated before volume expansion (5mL/kg bolus of lactated Ringer’s solution). The aortic velocity time integral (VTI) was measured before and after volume expansion as a surrogate of stroke volume. Dogs were considered responders (n=9) when the VTI increase was ≥15% and non-responders (n=15) when the increase was <15%. Results and ConclusionsBefore volume expansion, ΔVpeak, CVCDI and SPV were higher in responders than in non-responders (P=0.0009, P=0.0003, and P=0.0271, respectively). Receiver operating characteristic (ROC) curves were plotted for the three indices. The areas under the ROC curves for SPV, ΔVpeak, and CVCDI were 0.91 (CI 0.73–0.99; P=0.0001), 0.95 (CI 0.77–1; P=0.0001), and 0.78 (CI 0.56–0.92; P=0.015), respectively. The best cut-offs were 6.7% for SPV (sensitivity, 77.78%; specificity, 93.33%), 9.4% for ΔVpeak (sensitivity, 88.89%; specificity, 100%), and 24% for CVCDI (sensitivity, 77.78%; specificity, 73.33). In conclusion, ΔVpeak, CVCDI, and SPV are reliable predictors of fluid responsiveness in healthy dogs undergoing general anaesthesia and mechanical ventilation.

Does stroke volume variation predict fluid responsiveness in children: A systematic review and meta-analysis.

ObjectiveStroke volume variation (SVV) is a reliable predictor of fluid responsiveness in adult patients. However, the predictive value of SVV is uncertain in pediatric patients. We performed the first systematic meta-analysis to evaluate the diagnostic value of SVV in predicting fluid responsiveness in children.MethodsPUBMED, EMBASE, and Cochrane Central Register of Controlled Trials were searched up to December 2016. Original studies assessing the diagnostic accuracy of SVV in predicting fluid responsiveness in children were considered to be eligible. A random-effects model was used to calculate pooled values of sensitivity, specificity and diagnostic odds ratio with 95% CI. The summary receiver operating characteristic curve was estimated and area under the curve was calculated. Quality of the studies was assessed with the QUADAS-2 tool.ResultsSix studies with a total of 279 fluid boluses in 224 children were included. The analysis demonstrated a pooled sensitivity of 0.68 (95% CI,0.59–0.76), pooled specificity of 0.65 (95% CI, 0.57–0.73), pooled diagnostic odds ratio of 8.24 (95% CI, 2.58–26.30), and the summary area under the summary receiver operating characteristic curve of 0.81. However, significant inter-study heterogeneity was found (p<0.05, I2 = 61.3%), likely due to small sample size and diverse study characteristics.ConclusionsCurrent evidence suggests that SVV was of diagnostic value in predicting fluid responsiveness in children under mechanical ventilation. Given the high heterogeneity of published data, further studies are needed to confirm the diagnostic accuracy of SVV in predicting fluid responsiveness in pediatric patients.

Evaluation of pleth variability index as a predictor of fluid responsiveness during orthotopic liver transplantation

Fluid management is challenging and still remains controversial in orthotopic liver transplantation (OLT). The pleth variability index (PVI) has been shown to be a reliable predictor of fluid responsiveness of perioperative and critically ill patients; however, it has not been evaluated in OLT. This study was designed to examine whether the PVI can reliably predict fluid responsiveness in OLT and to compare PVI with other hemodynamic indexes that are measured using the PiCCO2 monitoring system. Twenty-five patients were enrolled in this study. Each patient was monitored using the noninvasive Masimo and PiCCO2 monitoring system. PVI was obtained with a Masimo pulse oximeter. Cardiac index was obtained using a transpulmonary thermodilution technique (CITPTD). Stroke volume variation (SVV), pulse pressure variation, and systemic vascular resistance index were measured using the PiCCO2 system. Fluid loading (10 mL/kg colloid) was performed at two different phases during the operation, and fluid responsiveness was defined as an increase in CITPTD ≥ 15%. During the dissection phase and the anhepatic phase, respectively, 14 patients (56%) and 18 patients (75%) were classified as responders. There were no differences between the baseline values of the PVI of responders and nonresponders. Area under the curve for PVI was 0.56 (sensitivity 35%, specificity 90%, p = 0.58) at dissection phase, and was 0.55 (sensitivity 55%, specificity 66%, p = 0.58) at anhepatic phase. Of the parameters, a higher area under the curve value was found for SVV. We conclude that PVI was unable to predict fluid responsiveness with sufficient accuracy in patients undergoing OLT, but the SVV parameter was reliable.

Ultrasonographic measurements of the inferior vena cava variation as a predictor of fluid responsiveness in patients undergoing anesthesia for surgery

BackgroundBoth hypovolemia and hypervolemia are connected with increased morbidity and mortality in the treatment and prognosis of patients. An accurate assessment of volume state allows the optimization of organ perfusion and oxygen supply. Recently, ultrasonography has been used to detect hypovolemia in critically ill patients and perioperative patients. The objective of our study was to assess the correlation between inferior vena cava (IVC) variation obtained with ultrasound and stroke volume variation (SVV) measured by the Vigileo/FloTrac monitor, as fluid responsiveness indicators, in patients undergoing anesthesia for surgery. MethodsForty patients (American Society of Anesthesiologists grades I and II) scheduled for elective gastrointestinal surgery were enrolled in our study. After anesthesia induction, 6% hydroxyethyl starch solution was administered to patients as an intravenous (IV) fluid. The IVC diameters were measured with ultrasonography. SVV and stroke volume index (SVI) were obtained from the Vigileo monitor. All data were collected both before and after fluid challenge. ResultsForty patients underwent IVC sonographic measurements and SVV calculation. After fluid challenge, mean arterial pressure, central venous pressure, SVI, and IVC diameters increased significantly, whereas SVV decreased markedly. The correlation coefficient between the increase in SVI and the baseline of IVC variation after an IV fluid was 0.710, and receiver operating characteristic (ROC) curve was 0.85. The correlation coefficient between the increase in SVI and the baseline of SVV was 0.803 with an ROC curve of 0.93. Central venous pressure had no significant correlation with SVI. ConclusionsOur data show that IVC variation and SVV proved to be reliable predictors of fluid responsiveness in patients undergoing anesthesia for surgery with mechanical ventilation.

Does Inferior Vena Cava variability predict fluid responsiveness in critically ill patients with atrial fibrillation

To assess the reliability of the variability of the inferior vena cava diameter as an indicator of fluid responsiveness in critically ill patients with atrial fibrillation. Adult critically ill patients with atrial fibrillation requiring mechanical ventilation were enrolled. The variability of the inferior vena cava diameter (V(IVC)) was measured during a breath and then calculated as the maximum diameter (Dmax) minus minimum diameter (Dmin) divided by Dmin. All the hemodynamic parameters were collected at baseline and after a manoeuvre of passive leg raising (PLR). A 15% of VTI increase after the PLR was the criterion to identify the patients with or without fluid responsiveness. ROC curve was used to assess the sensitivity and specificity of V(IVC) as an indicator of fluid responsiveness for critically ill patients with atrial fibrillation. There were 34 patients enrolled in our study, with 14 of them responsed to PLR and the rest 20 did not. For patients with fluid responsiveness V(IVC) was significantly higher than patients without fluid responsiveness. The sensitivity and specificity of V(IVC) ≥ 16% to predict fluid responsiveness in patients with atrial fibrillation were 57.1% and 89.9% respectively. V(IVC) proved to be a reliable predictor of fluid responsiveness in critical ill patients with atrial fibrillation.

Bedside ultrasonographic measurement of the inferior vena cava fails to predict fluid responsiveness in the first 6 hours after cardiac surgery: a prospective case series observational study.

To assess validity of respiratory variation of inferior vena cava (IVC) diameter to predict fluid responsiveness and guide fluid therapy in mechanically ventilated patients during the first 6 hours after elective cardiac surgery. Prospective observational case series study. Single-center hospital. 50 consecutive patients undergoing elective cardiac surgery. Transthoracic bedside echocardiography. Parameters derived from ultrasonographic assessment of the IVC diameter (collapsibility index [CI], distensibility index [DI], and IVC/aorta index). In the whole study group, change in fluid balance correlated with change in IVC maximum diameter (p = 0.034, r = 0.176). IVC-CI and IVC-DI correlated with IVC/aorta index. A weak correlation between central venous pressure (CVP) and IVC-derived parameters (IVC-CI and IVC-DI) was noticed. Despite statistical significance (p<0.05), all observed correlations expressed low statistical power (r<0.21). There were no statistically significant differences between fluid responders and nonresponders in relation to clinical parameters, CVP, ultrasound IVC measurement, and IVC-derived indices. Dynamic IVC-derived parameters (IVC-CI, IVC-DI, and IVC/aorta index) and CVP are not reliable predictors of fluid responsiveness in the first 6 hours after cardiac surgery. Complexity of physiologic factors modulating cardiac performance in this group may be responsible for the difficulty in finding a plausible monitoring tool for fluid guidance. Bedside ultrasonographic measurement of IVC is unable to predict fluid responsiveness in the first 6 hours after cardiac surgery.

Efficacy of dynamic indices in predicting fluid responsiveness in patients with obstructive jaundice

Previous studies have shown that the stroke volume variation (SVV), the pulse pressure variation (PPV) and the pleth variability index (PVI) could be successfully used for predicting fluid responsiveness (FR) in surgical patients. The aim of this study was to validate the ability of SVV, PPV and PVI to predict intraoperative FR in mechanically ventilated patients with obstructive jaundice (OJ). Thirty-two patients with OJ (mean serum total bilirubin 190.5 ± 95.3 µmol L−1) received intraoperative volume expansion (VE) with 250 ml colloids immediately after an exploratory laparotomy had been completed and after a 5 min period of hemodynamic stability. Hemodynamic variables were recorded before and after VE. FR was defined as an increase in stroke volume index > 10% after VE. The ability of SVV, PPV and PVI to predict FR was assessed by calculation of the area under the receiver operating characteristic curve. Eleven (34%) patients were responders and 21 patients were nonresponders to VE. The PPV was the unique dynamic index that had the moderate ability to predict FR during surgical procedures, the area under the curve was 0.71 (95% CI, 0.523 to 0.856; P = 0.039) and the threshold (sensitivity and specificity) discriminated responders was 7.5% (63.6%/71.4%). The present study concluded that SVV and PVI were not reliable predictors of FR, but PPV has some value predicting FR in patients with OJ intraoperatively.

Stroke Volume Variation for Prediction of Fluid Responsiveness in Patients Undergoing Gastrointestinal Surgery

Background: Stroke volume variation (SVV) has been shown to be a reliable predictor of fluid responsiveness. However, the predictive role of SVV measured by FloTrac/Vigileo system in prediction of fluid responsiveness was unproven in patients undergoing ventilation with low tidal volume. Methods: Fifty patients undergoing elective gastrointestinal surgery were randomly divided into two groups: Group C [n1=20, tidal volume (Vt) = 8 ml/kg, frequency (F) = 12/min] and Group L [n2=30, Vt= 6 ml/kg, F=16/min]. After anesthesia induction, 6% hydroxyethyl starch130/0.4 solution (7 ml/kg) was intravenously transfused. Besides standard haemodynamic monitoring, SVV, cardiac output, cardiac index (CI), stroke volume (SV), stroke volume index (SVI), systemic vascular resistance (SVR) and systemic vascular resistance index (SVRI) were determined with the FloTrac/Vigileo system before and after fluid loading. Results: After fluid loading, the MAP, CVP, SVI and CI increased significantly, whereas the SVV and SVR decreased markedly in both groups. SVI was significantly correlated to the SVV, CVP but not the HR, MAP and SVR. SVI was significantly correlated to the SVV before fluid loading (Group C: r = 0.909; Group L: r = 0.758) but not the HR, MAP, CVP and SVR before fluid loading. The largest area under the ROC curve (AUC) was found for SVV (Group C, 0.852; Group L, 0.814), and the AUC for other preloading indices in two groups ranged from 0.324 to 0.460. Conclusion: SVV measured by FloTrac/Vigileo system can predict fluid responsiveness in patients undergoing ventilation with low tidal volumes during gastrointestinal surgery.

Dynamic indices do not predict volume responsiveness in routine clinical practice

Dynamic indices, including pulse pressure, systolic pressure, and stroke volume variation (PPV, SPV, and SVV), are accurate predictors of fluid responsiveness under strict conditions, for example, controlled mechanical ventilation using conventional tidal volumes (TVs) in the absence of cardiac arrhythmias. However, in routine clinical practice, these prerequisites are not always met. We evaluated the effect of regularly used ventilator settings, different calculation methods, and the presence of cardiac arrhythmias on the ability of dynamic indices to predict fluid responsiveness in sedated, mechanically ventilated patients. We prospectively evaluated 47 fluid challenges in 29 consecutive cardiac surgery patients. Patients were divided into different groups based on TV. Dynamic indices were calculated in various ways: calculation over 30 s, breath-by-breath (with and without excluding arrhythmias), and with correction for TV. The predictive value was optimal in the group ventilated with TVs >7 ml kg(-1) with correction for TV, calculated breath-by-breath, and with exclusion of arrhythmias [area under the curve (AUC)=0.95, 0.93, and 0.90 for PPV, SPV, and SVV, respectively]. Including patients ventilated with lower TVs decreased the predictive value of all dynamic indices, while calculating dynamic indices over 30 s and not excluding cardiac arrhythmias further reduced the AUC to 0.51, 0.63, and 0.51 for PPV, SPV, and SVV, respectively. PPV, SPV, and SVV are the only reliable predictors of fluid responsiveness under strict conditions. In routine clinical practice, factors including low TV, cardiac arrhythmias, and the calculation method can substantially reduce their predictive value.

Fluid responsiveness during weaning from mechanical ventilation

To overcome the limited accuracy of functional hemodynamic parameters such as stroke volume and pulse pressure variation (SVV and PPV) during spontaneous breathing, a passive leg raising (PLR) maneuver has been suggested as a reliable predictor of fluid responsiveness [1,2]. The aim of this study was to evaluate fluid responsiveness using SVV, PPV and PLR during the transition from controlled to spontaneous breathing.

Pulse Pressure Variation Predicts Fluid Responsiveness in Elderly Patients After Coronary Artery Bypass Graft Surgery

To assess the ability of pulse pressure variation to predict fluid responsiveness in mechanically ventilated elderly patients after coronary artery bypass graft surgery. A prospective, interventional study. An academic, tertiary referral hospital. Sixty patients >70 years old and mechanically ventilated after coronary artery bypass graft surgery. Intravascular volume expansion using 6% hydroxyethyl starch solution, 7 mL/kg over 20 minutes. Heart rate, arterial blood pressure, pulse pressure variation, central venous pressure, pulmonary artery occlusion pressure, and stroke volume index were measured immediately before and after volume expansion. Fluid responsiveness was defined as an increase in stroke volume index ≥ 15% after volume expansion. Forty-one patients were fluid responders and 19 patients were nonresponders. In contrast to central venous pressure or pulmonary artery occlusion pressure, pulse pressure variation was higher in the responders than in the nonresponders (22 ± 6% v 9.3 ± 3%, p = 0.001) and correlated with the percent changes in the stroke volume index after volume expansion (r = 0.47, p = 0.001). The area under the receiver operating characteristic curve for pulse pressure variation was 0.85 (95% confidence interval 0.75-0.94). The threshold value of 11.5% allowed the discrimination between responders and nonresponders with a sensitivity of 80% and a specificity of 74%. Pulse pressure variation is a reliable predictor of fluid responsiveness in mechanically ventilated elderly patients after coronary artery bypass graft surgery.

Non-invasive measurement of pulse pressure variation and systolic pressure variation using a finger cuff corresponds with intra-arterial measurement

Pulse pressure variation (PPV) and systolic pressure variation (SPV) are reliable predictors of fluid responsiveness in patients undergoing controlled mechanical ventilation. Currently, PPV and SPV are measured invasively and it is unknown if an arterial pressure (AP) signal obtained with a finger cuff can be used as an alternative. The aim of this study was to validate PPV and SPV measured using a finger cuff. Patients receiving mechanical ventilation under sedation after cardiac artery bypass graft (CABG) surgery were included after arrival on the intensive care unit. AP was measured invasively in the radial artery and non-invasively using the finger cuff of the Nexfin™ monitor. I.V. fluid challenges were administered according to clinical need. The mean value of PPV and SVV was calculated before and after administration of a fluid challenge. Agreement of the calculated PPV and SPV from both methods was assessed using the Bland-Altman analysis. Nineteen patients were included and 28 volume challenges were analysed. Correlation between the two methods for PPV and SPV [mean (sd)=6.9 (4.3)% and 5.3 (2.6)%, respectively] was r=0.96 (P<0.0001) and r=0.95 (P<0.0001), respectively. The mean bias was -0.95% for PPV and -0.22% for SPV. Limits of agreement were -4.3% and 2.4% for PPV and -2.2% and 1.7% for SPV. The correlation between changes in PPV and SPV as a result of volume expansion measured by the two different methods was r=0.88 (P<0.0001) and r=0.87 (P<0.0001), respectively. In patients receiving controlled mechanical ventilation after CABG, PPV and SPV can be measured reliably non-invasively using the inflatable finger cuff of the Nexfin™ monitor.

Using arterial pressure waveform analysis for the assessment of fluid responsiveness

Predicting the effects of volume expansion on cardiac output and oxygen delivery is of major importance in different clinical scenarios. Functional hemodynamic parameters based on pulse waveform analysis, which are relying on the effects of mechanical ventilation on stroke volume and its surrogates, have been shown to be reliable predictors of fluid responsiveness during anesthesia and intensive care unit treatment, as demonstrated by several clinical studies and meta-analyses. However, different limitations of these parameters have to be considered when they are used in clinical practice. Today, they can be continuously and automatically monitored by a variety of commercially available devices. These parameters have been introduced into the concept of perioperative fluid management and hemodynamic optimization – an approach that may positively impact postoperative patients’ outcomes. In this article, technical aspects of the assessment of the functional hemodynamic parameters derived from pulse waveform analysis are summarized, emphasizing their advantages, limitations and potential applications, primarily in a perioperative setting in order to improve patient outcome.