Pulse Pressure Variation Values Research Articles

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.

Monitoring pulse pressure variation during lung resection surgery

Abstract Background and objective Although pulse pressure variation (PPV) is an effective dynamic parameter widely used to predict the increase in cardiac output after the administration of fluids in abdominal surgery, its use in thoracic surgery is controversial. A study was designed to describe the behaviour of PPV during lung resection surgery. Patients and methods A prospective observational study was conducted on adult patients scheduled for lung resection surgery. Patients with bleeding greater than 200cc, or those who required vasopressors during data collection, were excluded. The PPV values were collected during different phases: in bipulmonary ventilation (T1), after the start of single lung ventilation, and the opening of the thorax (T2), at the end of the procedure prior to the restoration of the bipulmonary ventilation (T3), and after the closure of the thorax in bipulmonary ventilation (T4). The correlation coefficient of the PPV values at the different times was calculated. Results The study included 50 consecutive patients. The mean values and standard deviations of PPV in the different phases were: T1, 11.14% (6.67); T2 6.24% (3.21, T3 5.68% (3.19); and T4 7.84% (4.61). The repeated ANOVA measurements found significant differences between the mean values of PPV in the different phases (p The correlation between the PPV values during T1 and T2 (PPVT1 and PPVT2) was r = 0.868 ([p Conclusions PPV presents a predictable behaviour in the course of lung resection surgery, characterised by a decrease of almost half at the beginning of the unipulmonary ventilation and opening of the thorax. It then remains stable throughout the surgery when there are no changes in the intravascular blood volume.

Comparison of the diagnostic accuracy of dynamic and static preload indexes to predict fluid responsiveness in mechanically ventilated, isoflurane anesthetized dogs

ObjectiveTo compare the diagnostic accuracy of pulse pressure variation (PPV), stroke volume variation from pulse contour analysis (SVVPCA), plethysmographic variability index (PVI), central venous pressure (CVP) and global end-diastolic volume index measured by transpulmonary thermodilution (GEDVITPTD) to predict fluid responsiveness (FR) in dogs. Study designProspective study. AnimalsA group of 40 bitches (13.8–26.8 kg) undergoing ovariohysterectomy. MethodsAnesthesia was maintained with isoflurane under volume-controlled ventilation (tidal volume 12 mL kg–1; inspiratory pause during 40% of inspiratory time; inspiration:expiration ratio 1:1.5). Transpulmonary thermodilution cardiac output was recorded through a femoral artery catheter. FR was evaluated by a fluid challenge (lactated Ringer's, 20 mL kg–1 over 15 minutes) administered once (n = 21) or twice (n = 18) before surgery. Individuals were responders if stroke volume index measured by transpulmonary thermodilution increased >15% after the last fluid challenge. ResultsOf the 39 animals studied, 21 were responders and 18 were nonresponders. Area under the receiver operating characteristics curve (AUROC) was 0.976, 0.906, 0.868 and 0.821 for PPV, PVI, CVP and SVVPCA, respectively (p < 0.0001 from AUROC = 0.5). GEDVITPTD failed to predict FR (AUROC: 0.660, p = 0.078). Best cut-off thresholds discriminating responders and nonresponders, with respective zones of diagnostic uncertainty (gray zones) were: PPV >16% (15–16%), PVI >11% (10–13%), SVVPCA >10% (9–18%) and CVP ≤1 mmHg (0–3 mmHg). Percentage of animals within gray zone limits was 13% (PPV), 28% (PVI), 51% (SVVPCA) and 67% (CVP). Conclusions and clinical relevancePPV has better diagnostic accuracy to predict FR (conclusive results in nearly 90% of population) than other preload indexes in healthy dogs. When invasive blood pressure is unavailable, PVI will predict FR with reasonable accuracy (conclusive results in approximately 70% of the population). PPV and PVI values above gray zone limits (>16% and >13%, respectively) can reliably predict responders to volume expansion.

Fluid responsiveness in hemodynamically unstable patients: a systematic review

Objective To evaluate the usefulness of different hemodynamic measurements in the detection of fluid responsiveness (FR) among patients with hemodynamic instability. Backgrounds Close hemodynamic monitoring of unstable patients' response to volume expansion is a central component of intensive care. Previous reports demonstrated that only 50% of patients respond to fluid administration with an increase in stroke volume or cardiac output. Data sources A computer literature search of PubMed, Scopus, and Cochrane Central was conducted. Study selection Records were screened for eligible studies according to the predetermined inclusion criteria. Data extraction Data were extracted and synthesized using standardized tables. Data synthesis Data were synthesized qualitatively, and we did not perform a quantitative data analysis. Findings The present review included 21 studies of moderate to high quality. All included studies found that CVP does neither correlate with intravascular volume nor accurately predict the FR. The included studies showed significant heterogeneity regarding the predictive value of pulse pressure variation and stroke volume variation. Passive leg raising-induced changes in cardiac output or related parameters were highly predictive for FR. Conclusion The current literature suggests that the static measures are not reliable indicators of FR. Dynamic indices are of good predictive value regarding FR. In addition, passive leg raising appears to be the most useful test for predicting FR in hemodynamically unstable adults.

Evaluation of volume responsiveness by pulse pressure variability and inferior vena cava dispensability index at different tidal volumes by mechanical ventilation.

This study investigated the effects of tidal volume (TV) on the diagnostic value of pulse pressure variation (PPV) and the inferior vena cava dispensability index (IVC-DI) for volume responsiveness during mechanical ventilation. In patients undergoing elective surgery with mechanical ventilation, different TVs of 6, 9, and 12 mL/kg were given for two min. The left ventricular outflow tract velocity-time integral (VTI) was measured by transthoracic echocardiography. The IVC-DI was measured at sub-xyphoid transabdominal long axis. The PPV was measured via the radial artery and served as baseline. Index measurements were repeated after fluid challenge. VTI increased by more than 15% after fluid challenge, which was considered as volume responsive. Seventy-nine patients were enrolled, 38 of whom were considered positive volume responsive. Baseline data between the response group and the non-response group were similar. Receiver operating characteristic curve confirmed PPV accuracy in diagnosing an increase in volume responsiveness with increased TV. When TV was 12 mL/kg, the PPV area under the curve (AUC) was 0.93 and the threshold value was 15.5%. IVC-DI had the highest diagnostic accuracy at a TV of 9 mL/kg and an AUC of 0.79, with a threshold value of 15.3%. When TV increased to 12 mL/kg, the IVC-DI value decreased. When the TV was 9 and 12 mL/kg, PPV showed improved performance in diagnosing volume responsiveness than did IVC-DI. PPV diagnostic accuracy in mechanically ventilated patients was higher than IVC-DI. PPV accuracy in predicting volume responsiveness was increased by increasing TV.

Monitorización de la variación de la presión de pulso durante la cirugía de resección pulmonar

Background and objectiveAlthough pulse pressure variation (PPV) is an effective dynamic parameter widely used to predict the increase in cardiac output after the administration of fluids in abdominal surgery, its use in thoracic surgery is controversial. A study was designed to describe the behaviour of PPV during lung resection surgery. Patients and methodsA prospective observational study was conducted on adult patients scheduled for lung resection surgery. Patients with bleeding greater than 200cc, or those who required vasopressors during data collection, were excluded. The PPV values were collected during different phases: in bipulmonary ventilation (T1), after the start of single lung ventilation, and the opening of the thorax (T2), at the end of the procedure prior to the restoration of the bipulmonary ventilation (T3), and after the closure of the thorax in bipulmonary ventilation (T4). The correlation coefficient of the PPV values at the different times was calculated. ResultsThe study included 50 consecutive patients. The mean values and standard deviations of PPV in the different phases were: T1, 11.14% (6.67); T2 6.24% (3.21, T3 5.68% (3.19), and T4 7.84% (4.61). The repeated ANOVA measurements found significant differences between the mean values of PPV in the different phases (P<.001).The correlation between the PPV values during T1 and T2 (PPVT1 and PPVT2) was r=0.868 ([P<.001], r2=0.753), while between T3 and T4 (PPVT3 and PPVT4) the correlation was r=0.616 ([P<.001], r2=0.379) between the PPV values in T3 and T4. ConclusionsPPV presents a predictable behaviour in the course of lung resection surgery, characterised by a decrease of almost half at the beginning of the unipulmonary ventilation and opening of the thorax. It then remains stable throughout the surgery when there are no changes in the intravascular blood volume.

Pulse pressure variation and pleth variability index as predictors of fluid responsiveness in patients undergoing spinal surgery in the prone position.

BackgroundThis study investigated the ability of pulse pressure variation (PPV) and pleth variability index (PVI) to predict fluid responsiveness of patients undergoing spinal surgery in the prone position.Patients and methodsA total of 53 patients undergoing posterior lumbar spinal fusion in the prone position on a Jackson table were studied. PPV, PVI, and hemodynamic and respiratory variables were measured both before and after the administration of 6 mL/kg colloid in both the supine and prone positions. Fluid responsiveness was defined as a 15% or greater increase in stroke volume index, as assessed by esophageal Doppler monitor after fluid loading.ResultsIn the supine position, 40 patients were responders. The areas under the receiver operating characteristic (ROC) curves for PPV and PVI were 0.783 [95% CI 0.648–0.884, P<0.001] and 0.814 (95% CI 0.684–0.908, P<0.001), respectively. The optimal cut-off values of PPV and PVI were 10% (sensitivity 75%, specificity 62%) and 8% (sensitivity 78%, specificity 77%), respectively. In the prone position, 27 patients were responders. The areas under the ROC curves for PPV and PVI were 0.781 (95% CI 0.646–0.883, P<0.001) and 0.756 (95% CI 0.618–0.863, P<0.001), respectively. The optimal cut-off values of PPV and PVI were 7% (sensitivity 82%, specificity 62%) and 8% (sensitivity 67%, specificity 69%), respectively.ConclusionBoth PPV and PVI were able to predict fluid responsiveness; their predictive abilities were maintained in the prone position.

Reliability of Passive Leg Raising, Stroke Volume Variation and Pulse Pressure Variation to Predict Fluid Responsiveness During Weaning From Mechanical Ventilation After Cardiac Surgery: A Prospective, Observational Study.

During assisted ventilation and spontaneous breathing, functional haemodynamic parameters, including stroke volume variation (SVV) and pulse pressure variation (PPV), are of limited value to predict fluid responsiveness, and the passive leg raising (PLR) manoeuvre has been advocated as a surrogate method. We aimed to study the predictive value of SVV, PPV and PLR for fluid responsiveness during weaning from mechanical ventilation after cardiac surgery. Haemodynamic variables and fluid responsiveness were assessed in 34 patients. Upon arrival at the intensive care unit, measurements were performed during continuous mandatory ventilation (CMV) and spontaneous breathing with pressure support (PSV) and after extubation (SPONT). The prediction of a positive fluid responsiveness (defined as stroke volume increase >15% after fluid administration) was tested by calculating the specific receiver operating characteristic (ROC) curves. A significant increase in stroke volumes was observed during CMV, PSV and SPONT after fluid administration. There were 19 fluid responders (55.9%) during CMV, with 22 (64.7%) and 13 (40.6%) during PSV and SPONT, respectively. The predictive value for a positive fluid responsiveness (area under the ROC curve) for SVV was 0.88, 0.70 and 0.56; was 0.83, 0.69 and 0.48 for PPV; was 0.72, 0.74 and 0.70 for PLR during CMV, PSV and SPONT, respectively. During mechanical ventilation, adequate prediction of fluid responsiveness using SVV and PPV was observed. However, during spontaneous breathing, the reliability of SVV and PPV was poor. In this period, PLR as a surrogate was able to predict fluid responsiveness better than SVV or PPV but was less reliable than previously reported.

Finger and forehead photoplethysmography-derived pulse-pressure variation and the benefits of baseline correction

To non-invasively predict fluid responsiveness, respiration-induced pulse amplitude variation (PAV) in the photoplethysmographic (PPG) signal has been proposed as an alternative to pulse pressure variation (PPV) in the arterial blood pressure (ABP) signal. However, it is still unclear how the performance of the PPG-derived PAV is site-dependent during surgery. The aim of this study is to compare finger- and forehead-PPG derived PAV in their ability to approach the value and trend of ABP-derived PPV. Furthermore, this study investigates four potential confounding factors, (1) baseline variation, (2) PPV, (3) ratio of respiration and heart rate, and (4) perfusion index, which might affect the agreement between PPV and PAV. In this work, ABP, finger PPG, and forehead PPG were continuously recorded in 29 patients undergoing major surgery in the operating room. A total of 91.2 h data were used for analysis, from which PAV and PPV were calculated and compared. We analyzed the impact of the four factors using a multiple linear regression (MLR) analysis. The results show that compared with the ABP-derived PPV, finger-derived PAV had an agreement of 3.2 ± 5.1%, whereas forehead-PAV had an agreement of 12.0 ± 9.1%. From the MLR analysis, we found that baseline variation was a factor significantly affecting the agreement between PPV and PAV. After correcting for respiration-induced baseline variation, the agreements for finger- and forehead-derived PAV were improved to reach an agreement of − 1.2 ± 3.8% and 3.3 ± 4.8%, respectively. To conclude, finger-derived PAV showed better agreement with ABP-derived PPV compared to forehead-derived PAV. Baseline variation was a factor that significantly affected the agreement between PPV and PAV. By correcting for the baseline variation, improved agreements were obtained for both the finger and forehead, and the difference between these two agreements was diminished. The tracking abilities for both finger- and forehead-derived PAV still warrant improvement for wide use in clinical practice. Overall, our results show that baseline-corrected finger- and forehead-derived PAV may provide a non-invasive alternative for PPV.

The utility of limited trans-thoracic echocardiography in the stratification of pulse pressure variation: A feasibility study in major open abdominal surgery.

Background and Aim:Limitation in use of pulse pressure variation (PPV) in predicting fluid responsiveness (FR) in hypotensive patients is encountered when values are in the “gray zone” (8–13%). Dynamic arterial elastance (Eadyn= PPV/SVV) can be used in such situations to predict arterial pressure response to volume expansion (VE). In our study, we used respiratory variation of ascending aorta velocity time integral (AoVTI) calculated from suprasternal window as a surrogate of stroke volume variation (SVV). Fluids/vasopressors were administered to hypotensive patients intraoperatively based on value of Eadyn. Aim was to assess feasibility and utility of suprasternal echocardiography in the above-mentioned subset of patients.Materials and Methods:Hemodynamic data were monitored and respiratory variation in AoVTI was recorded using suprasternal echocardiography at all time points when patients developed hypotension (systolic blood pressure <90 mm Hg/<20% of baseline for 5 min) and at randomly selected time intervals when hemodynamic stability was maintained. VE with 250 ml of Ringer lactate (RL) was done in hypotensive patients with PPV value of 8–13% and Eadyn>0.9. Increase of >15% in AoVTI after VE defined “fluid responsiveness.”Results:Twenty-eight patients were enrolled, but three were excluded in view of left ventricular systolic dysfunction detected during preinduction echocardiography. Hemodynamic and echocardiographic data were recorded at 538 observation points in 25 adults. Hypotension occurred in 247 data sets, and in 168 data sets, value of PPV was 8–13%. VE was carried out in only those 131 data sets in which the value of Eadyn was >0.9. Area under the curve (AUC) for VE as an intervention in the indeterminate (PPV 8–13%) group was 0.574 (0.49–0.68, 95% CI, P < 0.049), and in the observation set with PPV >13, the AUC value was 0.7 (0.59–0.98, 95% CI, P < 0.01).Conclusions:Echocardiography using the suprasternal window in the operating room during abdominal surgery is feasible, but the utility of Eadyn in stratification of patients with PPV 8–13% is inconclusive.

On algorithms for calculating arterial pulse pressure variation during major surgery

Objective: Arterial pulse pressure variation (PPV) is widely used for predicting fluid responsiveness and supporting fluid management in the operating room and intensive care unit. Available PPV algorithms have been typically validated for fluid responsiveness during episodes of hemodynamic stability. Yet, little is known about the performance of PPV algorithms during surgery, where fast changes of the blood pressure may affect the robustness of the presented PPV value. This work provides a comprehensive understanding of how various existing algorithmic designs affect the robustness of the presented PPV value during surgery, and proposes additional processing for the pulse pressure signal before calculating PPV. Approach: We recorded arterial blood pressure waveforms from 23 patients undergoing major abdominal surgery. To evaluate the performance, we designed three clinically relevant metrics. Main results and Significance: The results show that all algorithms performed well during episodes of hemodynamic stability. Moreover, it is demonstrated that the proposed processing helps improve the robustness of PPV during the entire course of surgery.

Predictive values of pulse pressure variation and stroke volume variation for fluid responsiveness in patients with pneumoperitoneum.

Animal studies suggest that dynamic predictors remain useful in patients with pneumoperitoneum, but human data is conflicting. Our aim was to determine predictive values of pulse pressure variation (PPV) and stroke volume variation (SVV) in patients with pneumoperitoneum using LiDCORapid™ haemodynamic monitor. Standardised fluid challenges of colloid were administered to patients undergoing laparoscopic procedures, one fluid challenge per patient. Intra-abdominal pressure was automatically held at 12mmHg. Fluid responsiveness was defined as an increase in nominal stroke index (nSI) ≥ 10%. Linear regression was used to assess the ability of PPV and SVV to track the changes of nSI and logistic regression and area under the receiver operating curve (AUROC) to assess the predictive value of PPV and SVV for fluid responsiveness. Threshold values for PPV and SVV were obtained using the "gray zone" approach. A p < 0.05 was considered as statistically significant. 56 patients were included in analysis. 41 patients (73%) responded to fluids. Both PPV and SVV tracked changes in nSI (Spearman correlation coefficients 0.34 for PPV and 0.53 for SVV). Odds ratio for fluid responsiveness for PPV was 1.163 (95% CI 1.01-1.34) and for SVV 1.341 (95% CI 1.10-1.63). PPV achieved an AUROC of 0.674 (95% CI 0.518-0.830) and SVV 0.80 (95% CI 0.668-0.932). The gray zone of PPV ranged between 6.5 and 20.5% and that of SVV between 7.5 and 13%. During pneumoperitoneum, as measured by LiDCORapid™, PPV and SVV can predict fluid responsiveness, however their sensitivity is lower than the one reported in conditions without pneumoperitoneum. Trial registry number: (with the Australian New Zealand Clinical Trials Registry): ACTRN12612000456853.

Different predictivity of fluid responsiveness by pulse pressure variation in children after surgical repair of ventricular septal defect or tetralogy of Fallot.

Pulse pressure variation derived from the varied pulse contour method is based on heart-lung interaction during mechanical ventilation. It has been shown that pulse pressure variation is predictive of fluid responsiveness in children undergoing surgical repair of ventricular septal defect. Right ventricle compliance and pulmonary vascular capacitance in children with tetralogy of Fallot are underdeveloped as compared to those in ventricular septal defect. We hypothesized that the difference in the right ventricle-pulmonary circulation in the twogroups of children would affect the heart-lung interaction and therefore pulse pressure variation predictivity of fluid responsiveness following cardiac surgery. Infants undergoing complete repair of ventricular septal defect (n=38, 1.05±0.75years) and tetralogy of Fallot (n=36, 1.15±0.68years) clinically presenting with low cardiac output were enrolled. Fluid infusion with 5% albumin or fresh frozen plasma was administered. Pulse pressure variation was recorded using pressure recording analytical method along with cardiac index before and after fluid infusion. Patients were considered as responders to fluid loading when cardiac index increased ≥15%. Receiver operating characteristic curves analysis was used to assess the accuracy and cutoffs of pulse pressure variation to predict fluid responsiveness. The pulse pressure variation values before and after fluid infusion were lower in tetralogy of Fallot children than those in ventricular septal defect children (15.2±4.4% vs 19.3±4.4%, P<.001; 11.6±3.8 vs 15.4±4.3%, P<.001, respectively). In ventricular septal defect children, 27 were responders and 11 nonresponders. Receiver operating characteristic curve area was 0.89 (95% confidence interval, 0.77-1.01) and cutoff value 17.4% with a sensitivity of 0.89 and a specificity of 0.91. In tetralogy of Fallot children, 26 were responders and 10 were nonresponders. Receiver operating characteristic curve area was 0.79 (95% CI, 0.64-0.94) and cutoff value 13.4% with a sensitivity of 0.81 and a specificity of 0.80. Pulse pressure variation is predictive of fluid responsiveness in ventricular septal defect and tetralogy of Fallot patients following cardiac surgery.

Plethysmography variability index for prediction of fluid responsiveness during graded haemorrhage and transfusion in sevoflurane-anaesthetized mechanically ventilated dogs

ObjectiveTo examine the accuracy of plethysmography variability index (PVI) as a noninvasive indicator of fluid responsiveness in hypovolaemic dogs. Study designProspective experimental study. AnimalsSix adult healthy sevoflurane-anaesthetized Beagle dogs. MethodsDogs were anaesthetized with 1.3-fold their individual minimum alveolar concentration of sevoflurane. The lungs were mechanically ventilated after neuromuscular blockade with vecuronium bromide. Cardiopulmonary variables including mean arterial blood pressure (MAP), central venous pressure (CVP), transpulmonary thermodilution cardiac output (TPTDCO), stroke volume (SV), perfusion index (PI), pulse pressure variation (PPV), stroke volume variation (SVV) and PVI were determined during six stages of graded venous blood withdrawal (5 mL kg−1 increments) and six stages of graded blood infusion (5 mL kg−1 increments). The cardiopulmonary variables were analysed using paired t test or Wilcoxon signed rank test. Correlations between PPV and SVV or PVI were analysed by linear regression. The accuracy of PPV, SVV and PVI for predicting fluid responsiveness was examined by using receiver operating characteristic curve analysis. A value of p < 0.05 was considered statistically significant. ResultsBlood withdrawal resulted in significant increases in PPV and PVI and decreases in MAP, CVP, TPTDCO, SV and PI. Blood infusion resulted in significant increases in MAP, CVP, TPTDCO, SV and PI and decreases in PPV and PVI. PPV and PVI showed a relevant correlation (p < 0.001, r2 = 0.62) and threshold values of PPV ≥ 16% (sensitivity 71%, specificity 82%) and PVI ≥ 12% (sensitivity 78%, specificity 72%) for identifying fluid responsiveness. SVV did not change. Conclusions and clinical relevanceNoninvasive measurement of PVI predicted fluid responsiveness with moderate accuracy equal to PPV in sevoflurane-anaesthetized mechanically ventilated dogs. Provisional threshold values for identification of fluid responsiveness were PPV ≥ 16% and PVI ≥ 12%. Clinical trials are needed to confirm these threshold values in dogs.

Evaluation of the dynamic predictors of fluid responsiveness in dogs receiving goal-directed fluid therapy

ObjectivesGoal-directed fluid therapy (GDFT) based on pulse pressure variation (PPV) was used in anaesthetized dogs undergoing abdominal surgeries. The aims were 1) to evaluate the success rate of the PPV ≥13% in detecting fluid responsiveness [delta stroke volume (ΔSV) ≥10%]; 2) to assess the correlation between PPV, systolic pressure variation (SPV), Plethysmograph Variability Index (PVI) and central venous pressure (CVP) and 3) to establish the threshold value for the PVI that would predict a PPV value of ≥13% and indirectly discriminate responders from nonresponders to fluid therapy. Study designClinical, prospective, interventional study. AnimalsA total of 63 client-owned dogs scheduled for abdominal procedures. MethodsPPV and SPV were calculated manually from the invasive blood pressure trace on the Datex monitor. PVI was recorded from the Masimo pulse oximeter. Fluid challenge (10 mL kg−1 Compound Sodium Lactate) was performed when PPV was ≥13% and/or mean arterial pressure (MAP) < 60 mmHg. Fluid responsiveness was assessed by the transoesophageal Doppler probe. Cardiovascular parameters (heart rate, MAP, PPV, SPV, PVI, SV and if available, CVP) were measured before and after each fluid intervention. ResultsPPV ≥ 13% reliably predicted fluid responsiveness in 82.9% of cases. There was positive correlation between PPV and SPV (r = 0.84%), PPV and logPVI (r = 0.46) as well as SPV and logPVI (r = 0.45). Noninvasive PVI value ≥13% should predict PPV threshold value (13%) with 97% sensitivity and 68% specificity. There was no statistically significant correlation between PPV and CVP. ConclusionsPPV is a useful clinical tool to detect occult hypovolaemia and predict cardiovascular response to fluid challenge. Use of PPV is recommended as a part of GDFT in dogs undergoing abdominal procedures.

The added value of cardiac index and pulse pressure variation monitoring to mean arterial pressure-guided volume therapy in moderate-risk abdominal surgery (COGUIDE): a pragmatic multicentre randomised controlled trial.

There is disagreement regarding the benefits of goal-directed therapy in moderate-risk abdominal surgery. Therefore, we tested the hypothesis that the addition of non-invasive cardiac index and pulse pressure variation monitoring to mean arterial pressure-based goal-directed therapy would reduce the incidence of postoperative complications in patients having moderate-risk abdominal surgery. In this pragmatic multicentre randomised controlled trial, we randomly allocated 244 patients by envelope drawing in a 1:1 fashion, stratified per centre. All patients had mean arterial pressure, cardiac index and pulse pressure variation measured continuously. In one group, healthcare professionals were blinded to cardiac index and pulse pressure variation values and were asked to guide haemodynamic therapy only based on mean arterial pressure (control group). In the second group, cardiac index and pulse pressure variation values were displayed and kept within target ranges following a pre-defined algorithm (CI-PPV group). The primary endpoint was the incidence of postoperative complications within 30days. One hundred and seventy-five patients were eligible for final analysis. Overall complication rates were similar (42/94 (44.7%) vs. 38/81 (46.9%) in the control and CI-PPV groups, respectively; p=0.95). The CI-PPV group had lower mean (SD) pulse pressure variation values (9.5 (2.0)% vs. 11.9 (4.6)%; p=0.003) and higher mean (SD) cardiac indices (2.76 (0.62) lmin-1 .m-2 vs. 2.53 (0.66) l min-1 .m-2 ; p=0.004) than the control group. In moderate-risk abdominal surgery, we observed no additional value of cardiac index and pulse pressure variation-guided haemodynamic therapy to mean arterial pressure-guided volume therapy with regard to postoperative complications.

Pulse pressure variation as a guide for volume expansion in dogs undergoing orthopedic surgery

ObjectiveTo investigate whether pulse pressure variation (PPV) can predict fluid responsiveness in healthy dogs during clinical surgery. Study designProspective clinical study. AnimalsThirty-three isoflurane-anesthetized dogs with arterial hypotension during orthopedic surgery. MethodsFluid challenge with lactated Ringer's solution (15 mL kg−1 in 15 minutes) was administered in mechanically ventilated dogs (tidal volume 10 mL kg−1) with hypotension [mean arterial pressure (MAP) < 65 mmHg]. The volume expansion was considered effective if cardiac output (CO; transesophageal Doppler) increased by ≥ 15%. Cardiopulmonary data were analyzed using two-way ANOVA, receiver operating characteristics (ROC) curves and Spearman coefficient; p < 0.05 was considered significant. ResultsEffective volume expansion, mean ± standard deviation 42 ± 4% increase in CO (p < 0.0001) was observed in 76% of the dogs, resulting in a decrease in PPV (p < 0.0001) and increase in MAP (p < 0.0001), central venous pressure (CVP; p = 0.02) and ejection fraction (p < 0.0001) compared with before the fluid challenge. None of these changes occurred when volume expansion resulted in a nonsignificant CO increase of 4 ± 5%. No significant differences were observed in blood gas analysis between responsive and nonresponsive dogs. The increase in CO was correlated with the decrease in PPV (r = −0.65; p < 0.0001) but absolute values of CO and PPV were not correlated. The PPV performance (ROC curve area: 0.89 ± 0.06, p = 0.0011) was better than that of CVP (ROC curve area: 0.54 ± 0.12) and MAP (ROC curve area: 0.59 ± 0.13) to predict fluid responsiveness. The best cut-off for PPV to distinguish responders and nonresponders was 15% (50% sensitivity and 96% specificity). Conclusions and clinical relevanceIn mechanically ventilated, healthy, isoflurane-anesthetized dogs, PPV predicted fluid responsiveness to volume expansion, and MAP and CVP did not show such applicability.

Arterial Pressure Variation in Elective Noncardiac Surgery: Identifying Reference Distributions and Modifying Factors.

Assessment of need for intravascular volume resuscitation remains challenging for anesthesiologists. Dynamic waveform indices, including systolic and pulse pressure variation, are demonstrated as reliable measures of fluid responsiveness for mechanically ventilated patients. Despite widespread use, real-world reference distributions for systolic and pulse pressure variation values have not been established for euvolemic intraoperative patients. The authors sought to establish systolic and pulse pressure variation reference distributions and assess the impact of modifying factors. The authors evaluated adult patients undergoing general anesthetics for elective noncardiac surgery. Median systolic and pulse pressure variations during a 50-min postinduction period were noted for each case. Modifying factors including body mass index, age, ventilator settings, positioning, and hemodynamic management were studied via univariate and multivariable analyses. For systolic pressure variation values, effects of data entry method (manually entered vs. automated recorded) were similarly studied. Among 1,791 cases, per-case median systolic and pulse pressure variation values formed nonparametric distributions. For each distribution, median values, interquartile ranges, and reference intervals (2.5th to 97.5th percentile) were, respectively, noted: these included manually entered systolic pressure variation (6.0, 5.0 to 7.0, and 3.0 to 11.0 mmHg), automated systolic pressure variation (4.7, 3.9 to 6.0, and 2.2 to 10.4 mmHg), and automated pulse pressure variation (7.0, 5.0 to 9.0, and 2.0 to 16.0%). Nonsupine positioning and preoperative β blocker were independently associated with altered systolic and pulse pressure variations, whereas ventilator tidal volume more than 8 ml/kg ideal body weight and peak inspiratory pressure more than 16 cm H2O demonstrated independent associations for systolic pressure variation only. This study establishes real-world systolic and pulse pressure variation reference distributions absent in the current literature. Through a consideration of reference distributions and modifying factors, the authors' study provides further evidence for assessing intraoperative volume status and fluid management therapies.

Noninvasive pulse pressure variation and stroke volume variation to predict fluid responsiveness at multiple thresholds: a prospective observational study.

BackgroundPulse pressure variation (PPV) and stroke volume variation (SVV) are dynamic preload variables that can be measured noninvasively to assess fluid responsiveness (FR) in anesthetized patients with mechanical ventilation. Few studies have examined the effectiveness of predicting FR according to the definition of FR, and assessment of inconclusive values of PPV and SVV around the cut-off value (the “grey zone”) might improve individual FR prediction. We explored the ability of noninvasive volume clamp derived measurements of PPV and SVV to predict FR using the grey zone approach, and we assessed the influence of multiple thresholds on the predictive ability of the numerical definition of FR.MethodsNinety patients undergoing general surgery were included in this prospective observational study and received a 500 mL fluid bolus as deemed clinically required by the attending anesthesiologist. A minimal relative increase in stroke volume index (↑SVI) was used to define FR with different thresholds from 10-25%. The PPV, SVV, and SVI were measured using the Nexfin® device that employs noninvasive volume clamp plethysmography.ResultsThe area under the receiver operator characteristic curve gradually increased for PPV / SVV with higher threshold values (from 0.818 / 0.760 at 10% ↑SVI to 0.928 / 0.944 at 25% ↑SVI). The grey zone limits of both PPV and SVV changed from 9–16% (PPV) and 5–13% (SVV) at the 10% ↑SVI threshold to 18–21% (PPV) and 14–16% (SVV) at the 25% ↑SVI threshold.ConclusionNoninvasive PPV and SVV measurements allow an acceptable FR prediction, although the reliability of both variables is dependent on the intended increase in SVI, which improves substantially with concomitant smaller grey zones at higher ↑SVI thresholds.Electronic supplementary materialThe online version of this article (doi:10.1007/s12630-015-0464-2) contains supplementary material, which is available to authorized users.

Dynamic preload markers to predict fluid responsiveness during and after major gastrointestinal surgery: an observational substudy of the OPTIMISE trial

Stroke volume variation (SVV) and pulse pressure variation (PPV), termed dynamic markers of preload responsiveness, may predict the response to i.v. fluid in critically ill patients. However, the predictive accuracy of these variables during gastrointestinal surgery remains uncertain. Observational study of patients aged ≥50 yr undergoing major gastrointestinal surgery, enrolled in the OPTIMISE trial. Patients received six 250 ml fluid challenges with i.v. colloid solution (three during and three after surgery), while SVV and PPV were measured using the LiDCOrapid monitor (LiDCO Ltd, UK). Fluid responsiveness was defined as a stroke volume increase ≥10%. Area under the receiver operating characteristic curve was calculated with 95% confidence intervals. Adjustment for covariates was performed by regression modelling and a clustering method was used to adjust for intra-patient correlation. One hundred patients were recruited between August 2010 and October 2012. Five hundred and fifty-six fluid challenges were administered and 159 (28.6%) were associated with increased stroke volume. The predictive value of both variables was poor during surgery [SVV 0.69 (0.63-0.77); PPV 0.70 (0.62-0.77)], and also after surgery [SVV 0.69 (0.63-0.78); PPV 0.64 (0.56-0.73)]. The findings were similar when analysed according to whether patients were mechanically ventilated [SVV 0.68 (0.63-0.77); PPV 0.69 (0.61-0.77)] or breathing spontaneously [SVV 0.69 (0.61-0.77); PPV 0.63 (0.56-0.72)]. Predictive value improved slightly in a sensitivity analysis excluding outlier values of SVV and PPV. In this study, the predictive accuracy of SVV and PPV for fluid responsiveness was insufficient to recommend for routine clinical use during or after major gastrointestinal surgery.