Accurate Predictor Of Fluid Responsiveness Research Articles

Evaluation of a Nurse-Driven Fluid Management Protocol to Improve Outcomes in Critically Ill Patients.

This article reports results of a nurse-driven fluid management protocol in a medical-surgical intensive care unit (ICU). Use of static measures such as central venous pressure monitoring, heart rate, blood pressure, and urine output is poor predictors of fluid responsiveness and can result in inappropriate fluid administration. Indiscriminate administration of fluid can result in prolonged mechanical ventilation time, increased vasopressor requirements, increased length of stay, and greater costs. Use of dynamic preload parameters such as stroke volume variation (SVV), pulse pressure variation, or changes in stroke volume with a passive leg raise has been shown to be more accurate predictors of fluid responsiveness. Improved patient outcomes including decreased length of hospital stay, reduction in kidney injury, decreased mechanical ventilation time and requirements, and reduced vasopressor requirements have been demonstrated by using dynamic preload parameters. ICU nurses were educated on cardiac output and dynamic preload parameters and a nurse-driven fluid replacement protocol was established. Knowledge scores, confidence scores, and patient outcomes were measured pre- and post-implementation. The results indicated that there was no change in knowledge scores between pre- and postimplementation groups (mean = 80%). There was a statistically significant increase in nurse confidence in using SVV (P = .003); however, this change is not clinically significant. There was no statistically significant difference in other confidence categories. The study indicated that ICU nurses were resistant to adoption of a nurse-driven fluid management protocol. While anesthesia clinicians are familiar with technologies to evaluate fluid responsiveness in the perioperative setting, the new technology posed challenges to ICU confidence. This project demonstrates that traditional methods of nursing education did not provide the support needed for implementation of a novel approach to fluid management, and that there is a need for further improvement in educational strategies.

Goal-directed fluid therapy guided by Plethysmographic Variability Index (PVI) versus conventional liberal fluid administration in children during elective abdominal surgery: A randomized controlled trial

BackgroundPVI has been shown to be an accurate predictor of fluid responsiveness in paediatric patients. Evidence regarding the role of PVI to guide intraoperative fluid therapy in paediatric abdominal surgery is lacking. We aimed to assess the effect of PVI-guided fluid therapy on the volume of intraoperative fluids administered and post-operative biochemical and recovery profile in children undergoing elective abdominal surgery. Methods42 children, 6 months-3 years scheduled for elective open bowel surgery were randomised to receive either ‘conventional liberal intraoperative fluids’ (liberal group) or ‘goal-directed intraoperative fluids’ (GDT group). PVI <13 was targeted in the GDT group. The primary outcome was the volume of intraoperative fluids administered. Postoperative serum lactate, base excess, hematocrit, recovery of bowel function and duration of postoperative hospital stay were the secondary outcomes. ResultsThe mean fluid administered intra-operatively was significantly lower in the GDT group as compared to the liberal group (24.1 ± 9.6 mL/kg vs 37.0 ± 8.9 mL/kg, p < 0.001). The postoperative hemoglobin concentration (g%) was significantly lower in the liberal group as compared to the GDT group (8.1 ± 1.3 vs 9.2 ± 1.4, p = 0.008). Recovery of bowel function (hours) was significantly delayed in the liberal group as compared to the GDT group (58.2 ± 17.9 vs 36.5 ± 14.1, p < 0.001). ConclusionIntraoperative PVI-guided fluid therapy significantly reduces the volume of intravenous crystalloids administered to children undergoing open bowel surgery. These children also had faster recovery of bowel function and less hemodilution in the immediate postoperative period, compared to those who received liberal intraoperative fluid therapy.Type of study: Randomized Clinical Trial.Level of evidence: Treatment Study (LEVEL 1).

Goal directed fluid and hemodynamic therapy with trans-thoracic echocardiographic aortic blood flow peak velocity variation in children and postoperative outcome : A randomized controlled trial protocol

Background : While several parameters of fluid responsiveness have been validated in adults, they cannot be directly applied in children primarily because of the pediatric specificities of the cardiovascular system. Respiratory variation of Aortic Blood Flow Peak Velocity (ΔVpeak) has been promoted as an accurate predictor of fluid responsiveness in children. Therefore, we aim at characterizing the potential impact of optimization of intraoperative hemodynamic condition using goal directed fluid and hemodynamic therapy (GDFHT based on ΔVpeak assessed by transthoracic echocardiography on postoperative outcome in children. Methods : Children aged less than 18 years old and admitted for major non cardiac surgery will be eligible. After obtaining parental consent, children will be randomized into two groups: Group GD, where fluid and hemodynamic therapy will be guided with ΔVpeak and Group SC, with fluid and hemodynamic therapy managed according to routine. Primary Outcome will be postoperative morbidity until 30 days postoperatively defined as surgical and/or organ failure. Secondary outcome will include length of stay in the intensive care unit, length of mechanical ventilation and length of hospital stay. Based on the primary end-point, 400 patients are required in order to have a significant difference between the two groups. Results and Conclusions : This multicenter randomized controlled trial will clarify the impact of GDFHT based on ΔVpeak assessed by transthoracic echocardiography on postoperative outcomes in children undergoing elective or urgent major non-cardiac surgery.

Effect of intraoperative volume status and hemodynamics on patients undergoing laparoscopic bariatric surgeries : A retrospective study

Introduction: The increasing trend and need of bariatric surgeries has made it vital for the anaesthesiologists to spruce up their knowledge regarding peri- operative management of morbidly obese patients. Intra-operative fluid management in such patients is critical and has always been debatable. Materials and Methods: We retrospectively assessed the influence of amount of fluid given intra-operative ly and effect of hemodynamics on the renal function tests and acid-base status of 103 morbidly obese patients undergoing laparoscopic bariatric surgery between April 2017 to March 2018 in our institution. All the patients received central venous pressure guided fluids and were divided into two groups on the basis of amount of fluid thereby administered as less than 2 litres and 2 litres or more. Results: In our study, slight metabolic acidosis was seen patients receiving less than 2 Litres of fluid while better hemodynamics were observed in patients receiving 2 litres of fluid or more intra -operatively. Conclusion: Obese patients coming for laparoscopic bariatric surgery should receive intra-operative fluids targeting optimal hemodynamics. Central venous pressure may not be an accurate predictor of fluid responsiveness. Keywords: Bariatric surgery Intraoperative fluid ,Morbidly obese, Biochemical outcome.

Does Respiratory Variation in Inferior Vena Cava Diameter Predict Fluid Responsiveness in Mechanically Ventilated Patients? A Systematic Review and Meta-analysis.

We performed a systematic review and meta-analysis of studies investigating the diagnostic accuracy of respiratory variation in inferior vena cava diameter (ΔIVC) for predicting fluid responsiveness in patients receiving mechanical ventilation. MEDLINE, EMBASE, the Cochrane Library, and Web of Science were screened from inception to February 2017. The meta-analysis assessed the pooled sensitivity, specificity, diagnostic odds ratio, and area under the receiver operating characteristic curve. In addition, heterogeneity and subgroup analyses were performed. A total of 12 studies involving 753 patients were included. Significant heterogeneity existed among the studies, and meta-regression indicated that ventilator settings were the main sources of heterogeneity. Subgroup analysis indicated that ΔIVC exhibited better diagnostic performance in the group of patients ventilated with tidal volume (TV) ≥8 mL/kg and positive end-expiratory pressure (PEEP) ≤5 cm H2O than in the group ventilated with TV <8 mL/kg or PEEP >5 cm H2O, as demonstrated by higher sensitivity (0.80 vs 0.66; P = .02), specificity (0.94 vs 0.68; P < .001), diagnostic odds ratio (68 vs 4; P < .001), and area under the receiver operating characteristic curve (0.88 vs 0.70; P < .001). The best ΔIVC threshold for predicting fluid responsiveness was 16% ± 2% in the group of TV ≥8 mL/kg and PEEP ≤5 cm H2O, whereas in the group of TV <8 mL/kg or PEEP >5 cm H2O, this threshold was 14% ± 5%. ΔIVC shows limited ability for predicting fluid responsiveness in distinct ventilator settings. In patients with TV ≥8 mL/kg and PEEP ≤5 cm H2O, ΔIVC was an accurate predictor of fluid responsiveness, while in patients with TV <8 mL/kg or PEEP >5 cm H2O, ΔIVC was a poor predictor. Thus, intensivists must be cautious when using ΔIVC.

The plethysmographic variability index does not predict fluid responsiveness estimated by esophageal Doppler during kidney transplantation: A controlled study.

Research is ongoing to find a noninvasive method of monitoring, which can predict fluid responsiveness in patients undergoing kidney transplantation.To compare the responses to fluid challenges with the Pleth Variability Index, a noninvasive dynamic index derived from plethysmographic variability (Radical 7 pulse oximeter; Masimo Corporation, Irvine, CA), and the esophageal Doppler, the criterion standard.Observational study.University hospital; study from May 2011 and May 2012.Forty-eight patients with end-renal function were included and 44 analyzed. Patients with cardiac failure were not eligible.Fluid challenges were administered during maintenance of general anesthesia but before skin incision and repeated if the patient was deemed to be a “responder” (increase in stroke volume ≥10%).The primary endpoint was to assess if the Pleth Variability Index is an accurate predictor of fluid responsiveness.Among 76 fluid challenges, 38 were considered as positive (increase in stroke volume measured by Doppler ≥10%). Pleth Variability Index was similar at baseline between responders and nonresponder patients. Fluid challenges were associated with a significant decrease in Pleth Variability Index in overall cases (12 [8–14] vs 10 [6–17], P = .050), but it was not able to discriminate between responders (12 [8–15] vs 10 [5–15], P = .650) and nonresponders (11 [6–16] vs 8 [5–14], P = .047). The area under the Receiver Operating Characteristic curve for Pleth Variability Index was 0.49 (0.36–0.62).Pleth Variability Index is not an accurate predictor of fluid responsiveness during kidney transplantation.

Noninvasive Blood Pressure Monitoring and Prediction of Fluid Responsiveness to Passive Leg Raising.

Intravenous fluid boluses are administered to patients in shock to improve tissue hypoperfusion. However, fluid boluses result in clinically significant stroke volume increases in only about 50% of patients. Hemodynamic responses to passive leg raising measured with invasive and minimally invasive methods are accurate predictors of fluid responsiveness. However, few studies have used noninvasive blood pressure measurement to evaluate responses to passive leg raising. To determine if passive leg raising-induced increases in pulse pressure or systolic blood pressure can be used to predict clinically significant increases in stroke volume index in healthy volunteers. In a repeated-measures study, hemodynamic measurements were obtained in 30 healthy volunteers before, during, and after passive leg raising. Each participant underwent the procedure twice. In the first test, 20 participants (69%) were responders (stroke volume index increased by ≥ 15%); 9 (31%) were nonresponders. In the second test, 15 participants (50%) were responders and 15 (50%) were nonresponders. A passive leg raising-induced increase in pulse pressure of 9% or more predicted a 15% increase in stroke volume index (sensitivity, 50%; specificity, 44%). There was no association between passive leg raising-induced changes in systolic blood pressure and fluid responsiveness. A passive leg raising-induced change in stroke volume index measured by bioreactance differentiated fluid responders and nonresponders. Pulse pressure and systolic blood pressure measured by oscillometric noninvasive blood pressure monitoring were not sensitive or specific predictors of fluid responsiveness in healthy volunteers.

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.

Meta-Analysis of Ventilated versus Spontaneously Breathing Patients in Predicting Fluid Responsiveness by Inferior Vena Cava Variation

Purpose: Respiratory variation in inferior vena cava (ΔIVC) has been extensively studied in predicting fluid responsiveness, but the results are conflicting. We performed a systemic review and meta-analysis of studies aiming at investigating the diagnostic accuracy of ΔIVC in predicting fluid responsiveness. Methods: MEDLINE, EMBASE, Cochrane Database and Web of Science were screened for relevant original and review articles from inception to July 2016. The meta-analysis determined the pooled sensitivity, specificity, diagnostic odds ratio (DOR) and area under the ROC curve (AUROC). In addition, subgroup analyses were performed in mechanically ventilated patients and spontaneously breathing patients. Results: A total of 20 studies involving 635 patients were included. Cutoff values of ΔIVC varied from 12% to 42%, the pooled sensitivity and specificity was 0.68 (0.62 - 0.75) and 0.80 (0.75 - 0.85), respectively. The DOR was 14.2 (6.0 - 33.6) and the AUROC was 0.86 (0.78 - 0.93). Subgroup analysis showed better diagnostic performance in patients on mechanical ventilation than in spontaneously breathing patients with higher sensitivity (0.75 vs. 0.56), specificity (0.82 vs. 0.78), DOR (22.9 vs. 7.9) and AUROC (0.90 vs. 0.80). The best threshold of ΔIVC in patients on mechanical ventilation was IVC distensibility index (ΔIVC ≥ 17% ± 4%), compared to IVC collapsibility index (ΔcIVC ≥ 33% ± 12%) in spontaneously breathing patients. Conclusion: ΔIVC is not an accurate predictor of fluid responsiveness in patients with acute circulatory failure. In patients on mechanical ventilation, the predicting ability of ΔIVC was moderate with acceptable sensitivity and specificity; in spontaneously breathing patients, the specificity remains acceptable but its sensitivity is poor.

Respiratory variation in aortic blood flow peak velocity to predict fluid responsiveness in mechanically ventilated children: a systematic review and meta-analysis.

Dynamic indices of preload have been shown to better predict fluid responsiveness than static variables in mechanically ventilated adults. In children, dynamic predictors of fluid responsiveness have not yet been extensively studied. To evaluate the diagnostic accuracy of respiratory variation in aortic blood flow peak velocity (ΔVPeak) for the prediction of fluid responsiveness in mechanically ventilated children. PubMed, Embase, and the Cochrane Database of Systematic Reviews were screened for studies relevant to the use of ΔVPeak to predict fluid responsiveness in children receiving mechanical ventilation. Clinical trials published as full-text articles in indexed journals without language restriction were included. We calculated the pooled values of sensitivity, specificity, diagnostic odds ratio (DOR), and positive and negative likelihood ratio using a random-effects model. In total, six studies (163 participants) met the inclusion criteria. Data are reported as point estimate with 95% confidence interval. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and DOR of ΔVPeak to predict fluid responsiveness for the overall population were 92.0% (84.1-96.7), 85.5% (75.6-92.5), 4.89 (2.92-8.18), 0.13 (0.07-0.25), and 50.44 (17.70-143.74), respectively. The area under the summary receiver operating characteristic curve was 0.94. Cutoff values for ΔVPeak to predict fluid responsiveness varied across studies, ranging from 7% to 20%. Our results confirm that the ΔVPeak is an accurate predictor of fluid responsiveness in children under mechanical ventilation. However, the question of the optimal cutoff value of ΔVPeak to predict fluid responsiveness remains uncertain, as there are important variations between original publications, and needs to be resolved in further studies. The potential impact of intraoperative cardiac output optimization using goal-directed fluid therapy based on ΔVPeak on the perioperative outcome in the pediatric population should be subsequently evaluated.

Stroke volume variation compared with pulse pressure variation and cardiac index changes for prediction of fluid responsiveness in mechanically ventilated patients

IntroductionAdequate volume resuscitation is very important for a favorable outcome of critically ill patients. Both over and under filling of intravascular volume could be deleterious. Static indices including central venous pressure, pulmonary capillary wedge pressure, left ventricular end-diastolic area, mean arterial pressure (MAP) and tachycardia are commonly used and are known to be of little value in discriminating responders from non-responders. On the other hand dynamic indices such as pulse pressure variation (PPV), inferior vena cava diameter, superior vena cava diameter, aortic blood flow, which are based on variation on the left ventricular stoke volume, have been shown to be more accurate predictors of fluid responsiveness in mechanically ventilated patients. In this study we are evaluating the ability of stroke volume variation (SVV) obtained by Vigileo–FloTrac device to predict fluid responsiveness in patients with acute circulatory failure under complete passive, volume controlled mechanical ventilation and correlating it to manually calculated PPV. Materials and methodsTwenty five patients aged above 18years, with acute circulatory failure and at least one sign of tissue hypoperfusion requiring fluid resuscitation and mechanical ventilation were included. Excluded are patients with cardiogenic shock, acute pulmonary edema, LVEF <50%, atrial fibrillation, frequent ectopics, significant aortic or mitral valve abnormalities or renal failure. Candidates were subjected to thorough clinical evaluation, lab investigation and ECG. Following sedation, muscle relaxation and maintenance of mean arterial pressure >65mmHg by norepinephrine, 500ml of Hes-steril were administered over 10min. Static and dynamic hemodynamic parameters were taken in supine position before and after fluid challenge. Patients who had an increase of cardiac index measured by trans-thoracic echocardiography ⩾15% of baseline measurement were considered responders. ResultsFourteen patients were fluid responders. Before fluid challenge SVV and PPV were significantly higher in responders than non-responders (p=0.0001 for each). SVV⩾8.15% predicted responders with a sensitivity of 100% and specificity 81.1% (AUC 0.906). PPV⩾10.2 also predicted responders with a sensitivity of 92.9% and specificity of 90.9% (AUC 0.974). The higher the SVV before fluid challenge the higher the percentage of increase of CI following fluid challenge (r=0.733, p=0.00). PPV showed the same correlation pattern with percentage increase of CI (r=0.798, p=0.00). ConclusionsBaseline stroke volume variation ⩾8.15% predicted fluid responsiveness in mechanically ventilated patients with acute circulatory failure. The study also confirmed the ability of pulse pressure variation to predict fluid responsiveness.

Fluid resuscitation in severe sepsis and septic shock: Shifting goalposts.

Fluid resuscitation in severe sepsis and septic shock: Shifting goalposts.

Respiration Signals from Photoplethysmography

Pulse oximetry is based on the technique of photoplethysmography (PPG) wherein light transmitted through tissues is modulated by the pulse. In addition to variations in light modulation by the cardiac cycle, the PPG signal contains a respiratory modulation and variations associated with changing tissue blood volume of other origins. Cardiovascular, respiratory, and neural fluctuations in the PPG signal are of different frequencies and can all be characterized according to their sinusoidal components. PPG was described in 1937 to measure blood volume changes. The technique is today increasingly used, in part because of developments in semiconductor technology during recent decades that have resulted in considerable advances in PPG probe design. Artificial neural networks help to detect complex nonlinear relationships and are extensively used in electronic signal analysis, including PPG. Patient and/or probe-tissue movement artifacts are sources of signal interference. Physiologic variations such as vasoconstriction, a deep gasp, or yawn also affect the signal. Monitoring respiratory rates from PPG are often based on respiratory-induced intensity variations (RIIVs) contained in the baseline of the PPG signal. Qualitative RIIV signals may be used for monitoring purposes regardless of age, gender, anesthesia, and mode of ventilation. Detection of breaths in adult volunteers had a maximal error of 8%, and in infants the rates of overdetected and missed breaths using PPG were 1.5% and 2.7%, respectively. During central apnea, the rhythmic RIIV signals caused by variations in intrathoracic pressure disappear. PPG has been evaluated for detecting airway obstruction with a sensitivity of 75% and a specificity of 85%. The RIIV and the pulse synchronous PPG waveform are sensitive for detecting hypovolemia. The respiratory synchronous variation of the PPG pulse amplitude is an accurate predictor of fluid responsiveness. Pleth variability index is a continuous measure of the respiratory modulation of the pulse oximeter waveform and has been shown to predict fluid responsiveness in mechanically ventilated patients including infants. The pleth variability index value depends on the size of the tidal volume and on positive end-expiratory pressure. In conclusion, the respiration modulation of the PPG signal can be used to monitor respiratory rate. It is probable that improvements in neural network technology will increase sensitivity and specificity for detecting both central and obstructive apnea. The size of the PPG respiration variation can predict fluid responsiveness in mechanically ventilated patients.

New analyses of standard physiological signals: the old pipes give the sweetest smoke

In this issue of the Journal of Clinical Monitoring and Computing, Giraud et al. investigated the impact of hypovolemia on the respiratory variations in the QRS amplitude on a classical DII EKG lead (DRDII) [1]. In this animal study, they were able to demonstrate that bleeding and volume expansion induced significant changes in DRDII and that these changes mirrored those observed in the respiratory variations in pulse pressure (PPV). These observations suggest that this non-invasive and potentially widely available parameter could predict fluid responsiveness and detect hypovolemia in operating rooms and intensive care units. Studies previously published in the Journal of Clinical Monitoring and Computing have already demonstrated a significant relationship between DRDII and PPV (and between DRDII and stroke volume variation) in mechanically ventilated patients under general anesthesia [2, 3]. The manuscript by Giraud et al. builds on these previous studies by showing that DRDII is also sensitive to manually induced changes in ventricular preload. The remaining steps before acceptance of this new index in clinical practice will be to: (1) show that it can independently predict fluid responsiveness; and (2) that its calculation can be automated and monitored continuously. Thus, while the study by Giraud et al. does not yet confirm this new index as an accurate predictor of fluid responsiveness, it is nevertheless a significant step towards validation. This study exemplifies a new trend in the analysis of physiological signals in which an old and readily available stream of data is processed in a novel way to yield new information. In the present case, the electrocardiogram (EKG) was first described over 100 years ago and has been in clinical use for patient monitoring for decades [4]. Despite this long history, the possible use of the EKG waveform in predicting fluid responsiveness is only now becoming clear. Interestingly, the approach described in the paper by Giraud et al. is very similar to what happened in the analysis of the plethysmographic waveform: both signals have been clinically available for decades but the analysis of their respiratory variations (DRDII for the EKG and DPOP for the plethysmographic waveform [5]) is a new concept which may have significant clinical utility [6]. The beauty of these new indices (if proven accurate) is that the equipment needed to obtain them is already available at the bedside and that they require very little computing in order to be obtained continuously and automatically. Additionally, they are cheap, and could be used almost anywhere. These old signals may thus provide universal, non-invasive, and inexpensive ways of monitoring fluid responsiveness in a variety of environments (hence the Irish proverb that ‘‘the old pipe gives the sweetest smoke’’). A similar trend has been observed in cardiac output (CO) monitoring [7]. The traditional clinical approach to monitoring CO is, of course, transpulmonary thermodilution, and this is still the preferred approach in many settings. The highly invasive nature of pulmonary artery catheters and the associated risk, however, makes them undesirable for routine CO monitoring across the full spectrum of surgical and intensive care patients. Newer J. Rinehart M. Cannesson (&) Department of Anesthesiology & Perioperative Care, University of California Irvine, 101 S City Drive, Orange, CA 92868, USA e-mail: mcanness@uci.edu

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.

Assessment fluid responsiveness in septic shock patients: a comparison of automated pulse pressure variation and manually calculated pulse pressure variation

Pulse pressure variation (PPV) is an accurate predictor of fluid responsiveness in mechanically ventilated patients. The aim of this study was the assessment and comparison of the ability of automated PPV, when measured by an IntelliVue MP 70 monitor, and manually calculated PPV to predict fluid responsiveness in mechanically ventilated septic shock patients.

Stroke volume variation and pleth variability index to predict fluid responsiveness during resection of primary retroperitoneal tumors in Hans Chinese

Respiration variation in arterial pulse pressure (ΔPP) and pulse oximetry plethysmographic waveform amplitude (ΔPOP) are accurate predictors of fluid responsiveness in mechanically ventilated patients. We hypothesized that stroke volume variation (SVV) and pleth variability index (PVI) can predict fluid responsiveness in mechanically ventilated patients during major surgical procedures in Hans Chinese. This prospective study consisted of fifty-five Hans Chinese patients undergoing resection of primary retroperitoneal tumors (PRPT). During the surgical procedures, hemodynamic data [central venous pressure (CVP), cardiac index (CI), stroke volume index (SVI), SVV, and PVI] were recorded before and after volume expansion (VE) (8 ml•kg-1 of 6% hydroxyethyl starch 130/0.4). Fluid responsiveness was defined as an increase in SVI ≥ 10% after VE. Four patients were excluded from analysis for arrhythmia or obvious hemorrhage during VE. Baseline SVV correlated well with baseline PVI and the changes in SVV was correlated with the changes in PVI (p < 0.01) after VE. There were significant increases of CI, SVI and decreases of SVV, PVI in responder (Rs) after VE. ROC results showed that the areas for SVV, PVI were significantly higher than the areas for CI, MAP, CVP, PI (p < 0.05). The best threshold values to predict fluid responsiveness were more than 12.5% for SVV and more than 13.5% for PVI in the real surgical setting. The baseline value of SVV, and PVI correlated significantly with volume-induced changes in SVI (p < 0.01). Both SVV and PVI could be used to predict intraoperative fluid responsiveness during resection of PRPT in Hans Chinese.

Predicting fluid responsiveness with stroke volume variation despite multiple extrasystoles*

To investigate the ability of a new stroke volume variation algorithm to predict fluid responsiveness during general anesthesia and mechanical ventilation in animals with multiple extrasystoles. Prospective laboratory animal experiment. Investigational laboratory. Eight instrumented pigs. Eight anesthetized and mechanically ventilated pigs were monitored with an arterial line and a pulmonary artery catheter. Multiple extrasystoles were induced by right ventricular pacing (25% of heart beats). Arterial pressure waveforms were recorded and stroke volume variation was computed from the new and from the standard algorithm. The new stroke volume variation algorithm is designed to restore the respiratory component of the arterial pressure waveform despite multiple ectopic heart beats. Cardiac output was measured before and after 56 fluid boluses (7 mL/kg of 6% hydroxy ethyl starch) performed at different volemic states. A positive response to fluid boluses (>15% increase in cardiac output) was observed in 21 of 56 boluses. The new stroke volume variation was higher in responders than in nonresponders (19% ± 5% vs. 12% ± 3%, p < .05), whereas the standard stroke volume variation was similar in the two groups (29% ± 8% vs. 26% ± 11%, p = .4). Receiver operating characteristic curve analysis showed that the new stroke volume variation was an accurate predictor of fluid responsiveness (sensitivity = 86%, specificity = 85%, best cutoff value = 14%, area under the curve = 0.892 ±, whereas the standard stroke volume variation was not (area under the curve = 0.596 ± 0.077). In contrast to the standard stroke volume variation, the new stroke volume variation algorithm was able to predict fluid responsiveness in animals with multiple ventricular extrasystoles.

Influence of the site of measurement on the ability of plethysmographic variability index to predict fluid responsiveness

Plethysmographic variability index (PVI) is an accurate predictor of fluid responsiveness in mechanically ventilated patients. However, the site of measurement of the plethysmographic waveform impacts its morphology and its respiratory variation. The goal of this study was to investigate the ability of PVI to predict fluid responsiveness at three sites of measurement (the forehead, ear, and finger) in mechanically ventilated patients under general anaesthesia. We studied 28 subjects after induction of general anaesthesia. Subjects were monitored with a pulmonary artery catheter and three pulse oximeter sensors (the finger, ear, and forehead). Pulse pressure variation, central venous pressure, cardiac index (CI), and PVI measured at the forehead, ear, and finger (PVI(forehead), PVI(ear), and PVI(finger)) were recorded before and after fluid loading (FL). Subjects were responders to volume expansion if CI increased >15% after FL. Areas under the receiver-operating curves to predict fluid responsiveness were 0.906, 0.880, and 0.836 for PVI(forehead), PVI(ear), and PVI(finger), respectively (P<0.05). PVI(forehead), PVI(ear), and PVI(finger) had a threshold value to predict fluid responsiveness of 15%, 16%, and 12% with sensitivities of 89%, 74%, and 74% and specificities of 78%, 74%, and 67%, respectively. PVI can predict fluid responsiveness in anaesthetized and ventilated subjects at all three sites of measurement. However, the threshold values for predicting fluid responsiveness differ with the site of measurement. These results support the use of this plethysmographic dynamic index in the cephalic region when the finger is inaccessible or during states of low peripheral perfusion.

Predicting fluid responsiveness in mechanically ventilated children under general anaesthesia using dynamic parameters and transthoracic echocardiography

Dynamic variables are accurate predictors of fluid responsiveness in adults undergoing mechanical ventilation. They can be determined using respiratory variation in aortic flow peak velocity (▵Vpeak), arterial pulse pressure [▵PP and pulse pressure variation (PPV)], or plethysmographic waveform amplitude [▵POP and pleth variability index (PVI)]. These indices have not been validated in children. We studied the ability of these variables to predict fluid responsiveness in mechanically ventilated children. All results are expressed as median [median absolute deviation (MAD)]. Thirty mechanically ventilated children were studied after undergoing general anaesthesia. Mechanical ventilation was maintained with a tidal volume of 10 ml kg(-1) of body weight. ▵PP, PPV, ▵POP, PVI, ▵Vpeak, and aortic velocity-time integral were recorded before and after volume expansion (VE). Patients were considered to be responders to VE when the aortic velocity-time integral increased more than 15% after VE. VE induced significant changes in ▵PP [13 (MAD 4) to 9 (5)%], PPV [15 (5) to 9 (5)%], ▵POP [15 (10) to 10 (6)%], PVI [13 (6) to 8 (5)%], and ▵Vpeak [16 (9) to 8 (3)%] (P<0.05 for all). Differences in ▵PP, ▵POP, PPV, and PVI did not reach statistical significance. Only ▵Vpeak was significantly different between responders (R) and non-responders (NR) to VE [22 (3) vs 7 (1)%, respectively; P<0.001]. The threshold ▵Vpeak value of 10% allowed discrimination between R and NR. In this study, ▵Vpeak was the most appropriate variable to predict fluid responsiveness.