Pulse Pressure Variation Research Articles

Cardiopulmonary interactions-which monitoring tools to use?

Heart-lung interactions occur due to the mechanical influence of intrathoracic pressure and lung volume changes on cardiac and circulatory function. These interactions manifest as respiratory fluctuations in venous, pulmonary, and arterial pressures, potentially affecting stroke volume. In the context of functional hemodynamic monitoring, pulse or stroke volume variation (pulse pressure variation or stroke volume variability) are commonly employed to assess volume or preload responsiveness. However, correct interpretation of these parameters requires a comprehensive understanding of the physiological factors that determine pulse pressure and stroke volume. These factors include pleural pressure, venous return, pulmonary vessel function, lung mechanics, gas exchange, and specific cardiac factors. A comprehensive knowledge of heart-lung physiology is vital to avoid clinical misjudgments, particularly in cases of right ventricular (RV) failure or diastolic dysfunction. Therefore, when selecting monitoring devices or technologies, these factors must be considered. Invasive arterial pressure measurements of variations in breath-to-breath pressure swings are commonly used to monitor heart-lung interactions. Echocardiography or pulmonary artery catheters are valuable tools for differentiating preload responsiveness from right ventricular failure, while changes in diastolic function should be assessed alongside alterations in airway or pleural pressure, which can be approximated by esophageal pressure. In complex clinical scenarios like ARDS, combined forms of shock or right heart failure, additional information on gas exchange and pulmonary mechanics aids in the interpretation of heart-lung interactions. This review aims to describe monitoring techniques that provide clinicians with an integrative understanding of a patient's condition, enabling accurate assessment and patient care.

Heart-Lung Interactions.

The pulmonary and cardiovascular systems have profound effects on each other. Overall cardiac function is determined by heart rate, preload, contractility, and afterload. Changes in lung volume, intrathoracic pressure (ITP), and hypoxemia can simultaneously change all of these four hemodynamic determinants for both ventricles and can even lead to cardiovascular collapse. Intubation using sedation depresses vasomotor tone. Also, the interdependence between right and left ventricles can be affected by lung volume-induced changes in pulmonary vascular resistance and the rise in ITP. An increase in venous return due to negative ITP during spontaneous inspiration can shift the septum to the left and cause a decrease in left ventricle compliance. During positive pressure ventilation, the increase in ITP causes a decrease in venous return (preload), minimizing ventricular interdependence and will decrease left ventricle afterload augmenting cardiac output. Thus, positive pressure ventilation is beneficial in acute heart failure patients and detrimental in hypovolemic patients where it can cause a significant decrease in venous return and cardiac output. Recently, this phenomenon has been used to assess patient's volume responsiveness to fluid by measuring pulse pressure variation and stroke volume variation. Heart-lung interaction is very dynamic and changes in lung volume, ITP, and oxygen level can have various effects on the cardiovascular system depending on preexisting cardiovascular function and volume status. Heart failure and either hypo or hypervolemia predispose to greater effects of ventilation of cardiovascular function and gas exchange. This review is an overview of the basics of heart-lung interaction.

Intraoperative plethysmography variability index directed fluid management versus standard care during intraabdominal surgery in cancer patients

Background: During the past 20 years, numerous publications have described the usefulness of systolic pressure variation, pulse pressure variation, stroke volume variation, etc., to guide intraoperative fluid administration. However, we still lack robust noninvasive physiological variables to successfully predict the response to fluid loading. Aims and Objectives: The present study was designed to evaluate the utility of plethysmography variability index (PVI) to optimize fluid management during intra-abdominal surgery in cancer patients. Materials and Methods: After the Institutional Ethics Committee approval and consent, 60 patients scheduled for elective lower abdominal cancer surgeries were randomized to receive fluid by either PVI-directed management (2 mL/kg/h) or using central venous pressure (8 mL/kg/h) after standardized technique of general and lumbar epidural anesthesia. The PVI was calculated by measuring changes in the PI during the respiratory cycle (PVI = [(PImax - PImin)/PImax] × 100). Arterial blood samples were taken at the time of incision and after 6 h postoperatively. Instances of intraoperative hypotension and oliguria were recorded. Results: Among the 60 patients enrolled in the study, demographic data, ASA status, duration of surgery, and hemodynamics were found to be comparable. The amount of crystalloid given was significantly lesser in Group P (984.70±51.16) as compared to Group C (2395.27±209.68) (P<0.001). Four patients in Group P and three patients in Group C required vasopressors. Conclusion: The use of PVI-guided fluid management was associated with lower lactate levels and crystalloid requirement. Reduced lactate levels in PVI-guided patients suggest that PVI-guided fluid management may be tailored to everyone’s needs.

Pulse Pressure Variation-Based Intraoperative Fluid Management Versus Traditional Fluid Management for Colon Cancer Patients Undergoing Open Mass Resection and Anastomosis: A Randomized Controlled Trial.

Bowel edema leads to decreased perfusion and oxygenation of the intestine at the anastomotic site after colonic mass resection with failure of healing and leakage. Additionally, dehydration causes bowel hypoperfusion and difficulty healing with more complications. Fluid therapy guided by dynamic monitoring of fluid response can help avoid bowel dehydration and edema with fewer complications. The main goal of this study was to compare the effects of intraoperative fluid therapy based on pulse pressure variation (PPV) to traditional fluid therapy to maintain adequate hydration without intraoperative instability of hemodynamics and postoperative complications. This randomized controlled study was conducted on 90 adult patients (age range: 18-70 years) undergoing elective open colonic mass resection and anastomosis at Eldemerdash Hospital, Ain Shams University, Cairo, Egypt. There were two groups of patients, namely group A (n = 45; conventional fluid management [CFM] group) and group B (n = 45; goal-guided fluid management [GGFM] group based on PPV), using randomly generated data from a computer. Intraoperative fluids and vasopressors were given using GGFM or routine care. The key tool for directing hemodynamic management in the GGFM algorithm was the fluid protocol and PPV. As a result, the outcomes were measured to include the volume of intraoperative fluid, water fraction, and postoperative complications. In this study, 90 patients underwent analysis. Both groups' demographics were similar (P > 0.05). Baseline characteristics and surgical procedures did not differ significantly between the two groups (P > 0.05). Both the amount of urine output and the intraoperative administration of crystalloids were statistically significantly higher in group A (P < 0.05). The two groups' heart rate, mean arterial pressure and intraoperative usage of colloids and ephedrine were not statistically different (P > 0.05). Water fraction, bowel recovery, anastomotic leak, and length of hospital stay were significantly higher in the CFM group (P < 0.05). For patients with the American Society of Anesthesiologists physical status I - II undergoing elective open resection of colonic mass and anastomosis, PPV-based GGFM, a less invasive tool for intraoperative fluid management, might be a better option than CFM.

Diagnostic accuracy of the peripheral venous pressure variation induced by an alveolar recruitment maneuver to predict fluid responsiveness during high-risk abdominal surgery

BackgroundIn patients undergoing high-risk surgery, it is recommended to titrate fluid administration using stroke volume or a dynamic variable of fluid responsiveness (FR). However, this strategy usually requires the use of a hemodynamic monitor and/or an arterial catheter. Recently, it has been shown that variations of central venous pressure (ΔCVP) during an alveolar recruitment maneuver (ARM) can predict FR and that there is a correlation between CVP and peripheral venous pressure (PVP). This prospective study tested the hypothesis that variations of PVP (ΔPVP) induced by an ARM could predict FR.MethodsWe studied 60 consecutive patients scheduled for high-risk abdominal surgery, excluding those with preoperative cardiac arrhythmias or right ventricular dysfunction. All patients had a peripheral venous catheter, a central venous catheter and a radial arterial catheter linked to a pulse contour monitoring device. PVP was always measured via an 18-gauge catheter inserted at the antecubital fossa. Then an ARM consisting of a standardized gas insufflation to reach a plateau of 30 cmH2O for 30 s was performed before skin incision. Invasive mean arterial pressure (MAP), pulse pressure, heart rate, CVP, PVP, pulse pressure variation (PPV), and stroke volume index (SVI) were recorded before ARM (T1), at the end of ARM (T2), before volume expansion (T3), and one minute after volume expansion (T4). Receiver-operating curves (ROC) analysis with the corresponding grey zone approach were performed to assess the ability of ∆PVP (index test) to predict FR, defined as an ≥ 10% increase in SVI following the administration of a 4 ml/kg balanced crystalloid solution over 5 min.Results∆PVP during ARM predicted FR with an area under the ROC curve of 0.76 (95%CI, 0.63 to 0.86). The optimal threshold determined by the Youden Index was a ∆PVP value of 5 mmHg (95%CI, 4 to 6) with a sensitivity of 66% (95%CI, 47 to 81) and a specificity of 82% (95%CI, 63 to 94). The AUC’s for predicting FR were not different between ΔPVP, ΔCVP, and PPV.ConclusionDuring high-risk abdominal surgery, ∆PVP induced by an ARM can moderately predict FR. Nevertheless, other hemodynamic variables did not perform better.

Predictors of fluid responsiveness in the operating room: a narrative review.

Prediction of fluid responsiveness has been considered an essential tool for modern fluid management. However, most studies in this field have focused on patients in intensive care unit despite numerous research throughout several decades. Therefore, the present narrative review aims to show the representative method's feasibility, advantages, and limitations in predicting fluid responsiveness, focusing on the operating room environments. Firstly, we described the predictors of fluid responsiveness based on heart-lung interaction, including pulse pressure and stroke volume variations, the measurement of respiratory variations of inferior vena cava diameter, and the end-expiratory occlusion test and addressed their limitations. Subsequently, the passive leg raising test and mini-fluid challenge tests were also mentioned, which assess fluid responsiveness by mimicking a classic fluid challenge. In the last part of this review, we pointed out the pitfalls of fluid management based on fluid responsiveness prediction, which emphasized the importance of individualized decision-making. Understanding the available representative methods to predict fluid responsiveness and their associated benefits and drawbacks through this review will aid anesthesiologists in choosing the most reliable methods for optimal fluid administration in each patient during anesthesia in the operating room.

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.

Usefulness of the velocity–time integral of the left ventricular outflow tract variability index to predict fluid responsiveness in patients undergoing cardiac surgery

BackgroundHaemodynamic monitoring of patients after cardiac surgery using echocardiographic evaluation of fluid responsiveness is both challenging and increasingly popular. We evaluated fluid responsiveness in the first hours after surgery by determining the variability of the velocity–time integral of the left ventricular outflow tract (VTI-LVOT).MethodsWe conducted a cross-sectional study of 50 consecutive adult patients who underwent cardiac surgery and in whom it was possible to obtain VTI-LVOT measurements. We then determined the variability and correlations with our pulse pressure variation (PPV) measurements to predict fluid responsiveness.ResultsA strong positive correlation was seen between the VTI-LVOT variability index absolute values and PPV for predicting fluid responsiveness in the first hours after cardiac surgery. We also found that the VTI-LVOT variability index has high specificity and a high positive likelihood ratio compared with the gold standard using a cut-off point of ≥ 12%.ConclusionsThe VTI-LVOT variability index is a valuable tool for determining fluid responsiveness during the first 6 postoperative hours in patients undergoing cardiac surgery.

The effect of restrictive vs. liberal fluid protocols on ocular parameters in patients undergoing prone spine surgery: a randomized controlled trial

BackgroundElevated intraocular pressure (IOP) and optic nerve edema occurring during prone surgeries may cause ocular and optic nerve ischaemia injury. We hypothesized that a liberal fluid protocol might further increase IOP and optic nerve sheath diameter (ONSD) than a restrictive fluid protocol for patients in the prone position.MethodsA single-centre, prospective and randomized trial was conducted. Patients were randomly allocated into 2 groups: the liberal fluid infusion group, in which repeated bolus doses of Ringer’s lactate solution were given to maintain pulse pressure variation (PPV) within 6~9%, and the restrictive fluid infusion group, where PPV was maintained within 13–16%. IOP and ONSD were measured in both eyes at 10min after the anaesthesia induction in the supine position, 10min after the prone position placement, and 1h and 2h since the prone position was placed, at the conclusion of surgery, and returned to the supine position.ResultsA total of 97 patients were recruited and completed the study. IOP increased significantly from 12±3mmHg in the supine position to 31±5 mmHg (p<0.001) at the end of surgery in the liberal fluid infusion group and from 12±2 to 28±4 mmHg (p<0.001) in the restrictive fluid infusion group. There was a statistically significant difference in the change of IOP over time between the two groups (p=0.019). ONSD increased significantly from 5.3±0.3mm in the supine position to 5.5±0.3mm (p<0.001) at the end of surgery in both groups (both p<0.001). There was no statistically significant difference in the change of ONSD over time between the two groups (p>0.05).ConclusionsCompared to the restrictive fluid protocol, the liberal fluid protocol increased IOP but not ONSD in patients undergoing prone spine surgery.Trial registrationThe study was registered in ClinicalTrials.gov (https://clinicaltrials.gov) prior to patient enrollment, ID: NCT03890510, on March 26, 2019. The principal investigator was Xiao-Yu Yang.

Dynamic arterial elastance for predicting mean arterial pressure responsiveness after fluid challenge in spontaneously breathing septic patients: A protocol for prospective observational study

Background: Fluid resuscitation is essential for patients with sepsis and septic shock; however, the response of blood pressure to fluids is still challenging. Dynamic arterial elastance (Eadyn), defined as the ratio between pulse pressure variation (PPV) and stroke volume variation (SVV), is one of the parameters that has been proposed to predict mean arterial pressure (MAP) response to fluid administration. PPV and SVV are obtained from the heart-lung interaction concepts, in which spontaneous breathing is an important limitation. In this study, we evaluate the accuracy (sensitivity and specificity) of Eadyn in predicting the MAP response after fluid administration in predicted fluid responsive, spontaneously breathing septic patients. Methods: Spontaneously breathing patients with sepsis or septic shock and acute circulatory failure who were predicted to be fluid responders by the passive leg raising test or the mini-fluid challenge test were enrolled. PPV, SVV, Eadyn and the other hemodynamic parameters were measured by an arterial catheter connected to FloTracTM sensor integrated with the HemoSphereTM platform before and after a fluid challenge. Patients were classified according to the increase in MAP after fluid administration into 2 groups: MAP-responders (MAP increase ≥ 10%) and MAP-nonresponders (MAP increase &lt; 10%). Hypothesis: In predicted fluid responders and spontaneously breathing septic patients, Eadyn should have predicted blood responsiveness. Ethics and dissemination: The Ramathibodi Human Research Ethics Committee has approved the trial. The findings plan to be presented in peer-reviewed publications and conferences in critical care medicine.

Central venous pressure and dynamic indices to assess fluid appropriateness in critically ill patients: A pilot study.

The correct identification of the appropriateness of fluid administration is important for the treatment of critically ill patients. Static and dynamic indices used to identify fluid responsiveness have been developed throughout the years, nonetheless fluid responsiveness does not indicate that fluid administration is appropriate, and indexes to evaluate appropriateness of fluid administration are lacking. The aim of this study was to evaluate if central venous pressure (CVP) anddynamic indices could correctly identify fluid appropriateness for critically ill patients. Data from 31 ICU patients, for a total of 53 observations, was included in the analysis. Patients were divided into two cohorts based on the appropriateness of fluid administration. Fluid appropriateness was defined in presence of a low cardiac index (< 2.5 l/min/m2) without any sign of fluid overload, as assessed by global end-diastolic volume index, extravascular lung water index or pulmonary artery occlusion pressure. For 10 patients, fluid administration was deemed appropriate, while for 21 patients it was deemed inappropriate. Central venous pressure was not different between the two cohorts (mean CVP 11 (4) mmHg in the fluid inappropriate group, 12 (4) mmHg in the fluid appropriate group, p 0.58). The same is true for pulse pressure variation (median PPV 5 [2, 9] % in the fluid inappropriate group, 4 [3, 13] % in the fluid appropriate group, p 0.57), for inferior vena cava distensibility (mean inferior vena cava distensibility 24 (14) % in the fluid inappropriate group, 22 (16) % in the fluid appropriate group, p 0.75) and for changes in end tidal carbon dioxide during a passive leg raising test (median d.ETCO2 1.5 [0.0, 2.0]% in the fluid inappropriate group, 1.0 [0.0, 2.0] % in the fluid appropriate group, p 0.98). There was no association between static and dynamic indices and fluid appropriateness. Central venous pressure, pulse pressure variation, changes in end tidal carbon dioxide during a passive leg raising test, inferior vena cava distensibility were not associated with fluid appropriateness in our cohorts.

PASSIVE LEG RAISING-INDUCED CHANGES IN PEAK VELOCITY VARIATION OF LEFT VENTRICULAR OUTFLOW TRACT TO PREDICT FLUID RESPONSIVENESS IN POSTOPERATIVE CRITICALLY ILL ELDERLY PATIENTS.

Background : Accurate prediction of fluid responsiveness is important for postoperative critically ill elderly patients. The objective of this study was to evaluate the predictive values of peak velocity variation (ΔVpeak) and passive leg raising (PLR)-induced changes in ΔVpeak (ΔVpeak PLR ) of the left ventricular outflow tract to predict fluid responsiveness in postoperative critically ill elderly patients. Method : Seventy-two postoperative elderly patients with acute circulatory failure who were mechanically ventilated with sinus rhythm were enrolled in our study. Pulse pressure variation (PPV), ΔVpeak, and stroke volume were collected at baseline and after PLR. An increase of >10% in stroke volume after PLR defined fluid responsiveness. Receiver operating characteristic curves and gray zones were constructed to assess the ability of ΔVpeak and ΔVpeak PLR to predict fluid responsiveness. Results : Thirty-two patients were fluid responders. The area under the receiver operating characteristic curves (AUC) for baseline PPV and ΔVpeak to predict fluid responsiveness was 0.768 (95% confidence interval [CI], 0.653-0.859; P < 0.001) and 0.899 (95% CI, 0.805-0.958; P < 0.001) with gray zones of 7.63% to 12.66% that included 41 patients (56.9%) and 9.92% to 13.46% that included 28 patients (38.9%). ΔPPV PLR predicted fluid responsiveness with an AUC of 0.909 (95% CI, 0.818-0.964; P < 0.001), and the gray zone was 1.49% to 2.93% and included 20 patients (27.8%). ΔVpeak PLR predicted fluid responsiveness with an AUC of 0.944 (95% CI, 0.863-0.984; P < 0.001), and the gray zone was 1.48% to 2.46% and included six patients (8.3%). Conclusions : Passive leg raising-induced changes in peak velocity variation of blood flow in the left ventricular outflow tract accurately predicted fluid responsiveness with a small gray zone in postoperative critically ill elderly patients.

Standardized blood volume changes monitored by capnodynamic hemodynamic variables: An experimental comparative study in pigs.

The capnodynamic method, based on Volumetric capnography and differential Fick mathematics, assess cardiac output in mechanically ventilated subjects. Capnodynamic and established hemodynamic monitoring parameters' capability to depict alterations in blood volume were investigated in a model of standardized hemorrhage, followed by crystalloid and blood transfusion. Ten anesthetized piglets were subjected to controlled hemorrhage (450 mL), followed by isovolemic crystalloid bolus and blood re-transfusion. Intravascular blood volume, and all hemodynamic variables, were determined twice after each intervention. The investigated hemodynamic variables were: cardiac output and stroke volume for capnodynamics and pulse contour analysis, respectively, pulse pressure and stroke volume variability and mean arterial pressure. One-way ANOVA and Tukey's test for multiple comparisons were used to identify significant changes. Trending was assessed by correlation and concordance. Concordance against intravascular volume changes for capnodynamic cardiac output and stroke volume were 96 and 94%, with correlations r = .78 and .68, (p < .0001) with significant changes for 6 and 5 of the 6 measuring points, respectively. Mean arterial pressure and pulse pressure variation had a concordance of 85% and 87%, r = .67 (p < .0001) and r = -.45 (p < .0001), respectively, and both changed significantly for 3 of 6 measuring points. Pulse contour stroke volume variation, stroke volume and cardiac output, showed concordance and correlation of 76%, r = -.18 (p = .11), 63%, r = .28 (p = .01) and 50%, r = .31 (p = .007), respectively and significant change for 1, 1 and 0 of the measuring points, respectively. Capnodynamic cardiac output and stroke volume did best depict the changes in intravascular blood volume. Pulse contour parameters did not follow volume changes in a reliable way.

Pulse Pressure Variability and the Risk of Fragility Fracture: The Kailuan Prospective Cohort Study in China

ObjectivesTo investigate the association of the magnitude and direction of pulse pressure variability (PPV) with the incidence of fragility fracture in the general population. MethodsThis prospective cohort study included current Kailuan Group employees and retirees who attended health checkups continuously from 2006 to 2010 and were followed up until December 31, 2021. A total of 56,129 individuals who completed the health checkups were selected and grouped according to coefficient of variation (CV) quartile for PPV. The standard deviation (SD) and variability independent of the mean were also calculated as measures of PPV. The cumulative incidence of fragility fracture in the four groups was calculated and the impact of PPV on the risk of fragility fracture was analyzed using a multivariate Cox regression model. The direction of the variation was also assessed. ResultsThere were 671 cases of fragility fracture (1.2%) during a median follow-up of 11 years. In the multivariable-adjusted model, the hazard ratio for fragility fracture was 1.37 (95% confidence interval 1.11–1.70) for the highest CV quartile for PPV versus the lowest CV quartile for PPV. There was a linear association between higher PPV and fragility fracture. Consistent results were noted for higher PPV and the risk of fragility fracture using other indices of variability and in various sensitivity and subgroup analyses. ConclusionsHigh PPV was associated with a higher rate of fragility fracture independently of blood pressure. Reduction of PPV may help to prevent fragility fractures in the general population.

Effect of visit-to-visit blood pressure variability on mild cognitive impairment and probable dementia in hypertensive patients receiving standard and intensive blood pressure treatment.

High visit-to-visit blood pressure variability (BPV) and hypertension are risk factors for mild cognitive impairment (MCI) and probable dementia (PD). Few articles assessed the effect of BPV on the MCI and PD in intensive blood pressure treatment and the different functions of three types of visit-to-visit BPV: systolic blood pressure variability (SBPV), diastolic blood pressure variability (DBPV) and pulse pressure variability (PPV). We performed a post hoc analysis of the SPRINT MIND trial. The primary outcomes were MCI and PD. BPV was measured by average real variability (ARV). The Kaplan-Meier curves were used to clarify the difference in tertiles of BPV. We fit Cox proportional hazards models to our outcome. We also did an interaction analysis between the intensive and standard groups. We enrolled 8,346 patients in the SPRINT MIND trial. The incidence of MCI and PD in the intensive group was lower than that in the standard group. 353 patients had MCI and 101 patients had PD in the standard group while 285 patients had MCI and 75 patients had PD in the intensive group. Tertiles with higher SBPV, DBPV and PPV in the standard group had a higher risk of MCI and PD (all p < 0.05). Meanwhile, higher SBPV and PPV in the intensive group were associated with an increased risk of PD (SBPV: HR(95%) = 2.1 (1.1-3.9), p = 0.026; PPV: HR(95%) = 2.0 (1.1-3.8), p = 0.025 in model 3) and higher SBPV in the intensive group was associated with an increased risk of MCI(HR(95%) = 1.4 (1.2-1.8), p < 0.001 in model 3). The difference between intensive and standard blood pressure treatment was not statistically significant when we considered the effect of the higher BPV on the risk of MCI and PD (all p for interaction >0.05). In this post hoc analysis of the SPRINT MIND trial, we found that higher SBPV and PPV were associated with an increased risk of PD in the intensive group, and higher SBPV was associated with an increased risk of MCI in the intensive group. The effect of higher BPV on the risk of MCI and PD was not significantly different in intensive and standard blood pressure treatment. These findings emphasized the need for clinical work to monitor BPV in intensive blood pressure treatment.

Evaluating carotid and aortic peak velocity variation as an alternative index for stroke volume and pulse pressure variation: a method comparison study

The peak velocity variation within the carotid artery (ΔVpeakCCA) and left ventricular outflow tract (ΔVpeakLVOT) is derived from the pulsed wave Doppler waveform and may predict fluid responsiveness. The aim of this study was to evaluate ΔVpeakCCA and ΔVpeakLVOT against calibrated stroke volume variation (SVV) and pulse pressure variation (PVV). Therefore, eighteen cardiac surgery patients were included in this prospective observational study. Doppler measurements were performed after induction of anesthesia, after a passive leg raise, and at the end of surgery. Simultaneously, SVV and PPV were measured by pulse-contour-analysis (PiCCO). The correlation, methodological agreement, concordance, and clinical agreement between Doppler and PiCCO measurements were assessed. The correlation between SVV and ΔVpeakCCA was strong (ρ = 0.88). Bland-Altman analysis demonstrated a bias of 0.01%, and LOA +/− 4.6%, acceptable concordance (93%), and close to acceptable clinical agreement (88%). For PPV and ΔVpeakCCA correlation was also strong (ρ = 0.73), bias was −0.2%, LOA +/− 7.6%, with intermediate acceptable concordance (90%), and low clinical agreement (72%). Analysis of ΔVpeakLVOT measurements demonstrated poor statistical agreement with SVV and PPV. In conclusion, in cardiac surgery patients ΔVpeakCCA, as opposed to ΔVpeakLVOT, has acceptable statistical and clinical agreement with SVV measurements. ΔVpeakCCA may qualify as a potential tool for non-invasive assessment of fluid responsiveness.

Peripheral Intravenous Waveform Analysis Responsiveness to Subclinical Hemorrhage in a Rat Model.

Early detection and quantification of perioperative hemorrhage remains challenging. Peripheral intravenous waveform analysis (PIVA) is a novel method that uses a standard intravenous catheter to detect interval hemorrhage. We hypothesize that subclinical blood loss of 2% of the estimated blood volume (EBV) in a rat model of hemorrhage is associated with significant changes in PIVA. Secondarily, we will compare PIVA association with volume loss to other static, invasive, and dynamic markers. Eleven male Sprague Dawley rats were anesthetized and mechanically ventilated. A total of 20% of the EBV was removed over ten 5 minute-intervals. The peripheral intravenous pressure waveform was continuously transduced via a 22-G angiocatheter in the saphenous vein and analyzed using MATLAB. Mean arterial pressure (MAP) and central venous pressure (CVP) were continuously monitored. Cardiac output (CO), right ventricular diameter (RVd), and left ventricular end-diastolic area (LVEDA) were evaluated via transthoracic echocardiogram using the short axis left ventricular view. Dynamic markers such as pulse pressure variation (PPV) were calculated from the arterial waveform. The primary outcome was change in the first fundamental frequency (F1) of the venous waveform, which was assessed using analysis of variance (ANOVA). Mean F1 at each blood loss interval was compared to the mean at the subsequent interval. Additionally, the strength of the association between blood loss and F1 and each other marker was quantified using the marginal R2 in a linear mixed-effects model. PIVA derived mean F1 decreased significantly after hemorrhage of only 2% of the EBV, from 0.17 to 0.11 mm Hg, P = .001, 95% confidence interval (CI) of difference in means 0.02 to 0.10, and decreased significantly from the prior hemorrhage interval at 4%, 6%, 8%, 10%, and 12%. Log F1 demonstrated a marginal R2 value of 0.57 (95% CI 0.40-0.73), followed by PPV 0.41 (0.28-0.56) and CO 0.39 (0.26-0.58). MAP, LVEDA, and systolic pressure variation displayed R2 values of 0.31, and the remaining predictors had R2 values ≤0.2. The difference in log F1 R2 was not significant when compared to PPV 0.16 (95% CI -0.07 to 0.38), CO 0.18 (-0.06 to 0.04), or MAP 0.25 (-0.01 to 0.49) but was significant for the remaining markers. The mean F1 amplitude of PIVA was significantly associated with subclinical blood loss and most strongly associated with blood volume among the markers considered. This study demonstrates feasibility of a minimally invasive, low-cost method for monitoring perioperative blood loss.

Noninvasive Assessment of Arterial Pulse-Pressure Variation During General Anesthesia: Clinical Evaluation of a New High-Fidelity Upper Arm Cuff

To compare noninvasive pulse-pressure variation (PPV) measurements obtained from a new high-fidelity upper arm cuff using a hydraulic coupling technique to corresponding intraarterial PPV measurements. The authors used prospective multicenter comparison and development studies for the new high-fidelity upper arm cuff. The study was performed in the departments of Anesthesiology at the Ludwig-Maximilians-Universität München Hospital, the University Hospital of Bonn, and the RoMed Hospital in Rosenheim (all Germany). A total of 153 patients were enrolled, undergoing major abdominal surgery or neurosurgery with mechanical ventilation. For the evaluation of PPV, 1,467 paired measurements in 107 patients were available after exclusion due to predefined quality criteria. Simultaneous measurements of PPV were performed from a reference femoral arterial catheter (PPVref) and the high-fidelity upper arm cuff (PPVcuff). The new device uses a semirigid conical shell. It incorporates a hydraulic sensor pad with a pressure transducer, leading to a tissue pressure-pulse contour with all characteristics of an arterial- pulse contour. The comparative analysis of the included measurements showed that PPVref and PPVcuff were closely correlated (r=0.92). The mean of the differences between PPVref and PPVcuff was 0.1 ± 2.0%, with 95% limits of agreement between -4.1% and 3.9%. To track absolute changes in PPV >2%, the concordance rate between the 2 methods was 93%. The new high-fidelity upper arm cuff method provided a clinically reliable estimate of PPV.

A Randomised Controlled Study Comparing Pulse Pressure Variation (PPV) and Pleth Variability Index (PVI) for Goal-Directed Fluid Therapy Intraoperatively in Patients Undergoing Intracranial (Supratentorial ICSOLs) Surgeries.

Fluid management in the perioperative period is a grey zone in clinical practice of late. Looking back on previous practices, static parameters were the only options. Now, dynamic parameters indicating fluid responsiveness have become a significant part of goal-directed fluid therapy (GDFT). However, the efficacy of this approach has yet to be established in neurosurgery cases where patients are already on lot of diuretics, thus making fluid management more challenging. The present study aims to determine the efficacy of the Pleth Variability Index (PVI) with pulse pressure variation (PPV) in guiding GDFT in patients undergoing neurosurgery for supra-tentorial intracranial space occupying lesions (ICSOLs), in the form of a randomised controlled trial. After randomisation, the patients were categorised into either PVI or PPV groups. Both received a baseline 2 ml/kg/h Lactated Ringer's (RL) infusion. Additional fluid boluses consisted of 250 ml of colloid infused over a 10 min period if PVI was > 15% or PPV was > 13% for at least five minutes. The primary outcome was to determine the serum lactate difference between preoperative and postoperative values, which could fairly predict fluid deficit leading to inadequate perfusion. A total of 74 patients were analysed. Both PVI- and PPV-guided GDFT strategies showed no significant difference in the postoperative lactate values, with a P-value of 0.18. Similarly, the mean total fluid administered, mean blood loss, length of CCU stay, and emetic and hypotension episodes also showed no significant differences among the groups with P-values of 0.41, 0.78, 0.25, 0.30, and 0.67, respectively. For patients undergoing neurosurgery (supratentorial ICSOLs), PVI seems to guide GDFT comparably to PPV regarding tissue perfusion and postoperative complications. However, both the parameters had low sensitivity and specificity, with an area of curve of 0.577 for PPV and 0.423 for PVI, as far as GDFT was concerned.

Significance of pulse pressure variability in predicting functional outcome in acute ischemic stroke: a retrospective, single-center, observational cohort study

This study aimed to determine the association between pulse pressure variability (PPV) and short- and long-term outcomes of acute ischemic stroke (AIS) patients. We studied 203 tertiary stroke center patients with AIS. PPV during 72 h after admission was analyzed using different variability parameters including standard deviation (SD). Patients’ outcome was assessed after 30 and 90 days post-stroke with modified Rankin Scale. The association between PPV and outcome was investigated using logistic regression analysis with adjustment for potential confounders. The predictive significance of PPV parameters was determined using area under the curve (AUC) of receiver operating characteristics. In the unadjusted logistic regression analysis, all PPV indicators were independently associated with unfavorable outcome at 30 days (i.a. Odds ratio (OR) = 4.817, 95%CI 2.283–10.162 per 10 mmHg increase in SD, p = 0.000) and 90 days (i.a. OR = 4.248, 95%CI 2.044–8.831 per 10 mmHg increase in SD, p = 0.000). After adjustment for confounders, ORs for all PPV indicators remained statistically significant. On the basis of AUC values, all PPV parameters were found relevant outcome predictors (p < 0.01). In conclusion, elevated PPV during first 72 h after admission due to AIS is associated with unfavorable outcome at 30 and 90 days, independent of mean blood pressure levels.