Pulse Pressure Variation Research Articles

Efficacy and safety of dynamic arterial elastance for weaning vasopressor support in septic shock patients: a randomised controlled trial protocol

IntroductionThe dynamic arterial elastance (EaDyn), calculated as pulse pressure variation divided by stroke volume variation, has been studied as a predictor of vasopressor weaning. However, its potential as a haemodynamic...

A retrospective study of the effects of a vasopressor bolus on systolic slope (dP/dt) and dynamic arterial elastance (Eadyn)

BackgroundTo enhance the utility of functional hemodynamic monitoring, the variables systolic slope (dP/dt) and dynamic arterial elastance (Eadyn) are calculated by the Hypotension Prediction Index (HPI) Acumen® Software. This study was designed to characterize the effects of phenylephrine and ephedrine on dP/dt and Eadyn.MethodsThis was a retrospective, non-randomized analysis of data collected during two clinical studies. All patients required intra-operative controlled mechanical ventilation and had an indwelling radial artery catheter connected to an Acumen IQ sensor. Raw arterial pressure waveform data was downloaded from the patient monitor and all hemodynamic measurements were calculated off-line. The anesthetic record was reviewed for bolus administrations of either phenylephrine or ephedrine. Cardiovascular variables prior to drug administration were compared to those following vasopressor administrations. The primary outcome was the difference for dP/dt and Eadyn at baseline compared with the average after the bolus administration. All data sets demonstrated non-normal distributions so statistical analysis of paired and unpaired data followed the Wilcoxon matched pairs signed-rank test or Mann-Whitney U test, respectively.Results201 doses of phenylephrine and 100 doses of ephedrine were analyzed. All data sets are reported as median [95% CI]. Mean arterial pressure (MAP) increased from 62 [54,68] to 78 [76,80] mmHg following phenylephrine and from 59 [55,62] to 80 [77,83] mmHg following ephedrine. Stroke volume and cardiac output both increased. Stroke volume variation and pulse pressure variation decreased. Both drugs produced significant increases in dP/dt, from 571 [531, 645] to 767 [733, 811] mmHg/sec for phenylephrine and from 537 [509, 596] to 848 [779, 930] mmHg/sec for ephedrine. No significant changes in Eadyn were observed.ConclusionBolus administration of phenylephrine or ephedrine increases dP/dt but does not change Eadyn. dP/dt demonstrates potential for predicting the inotropic response to phenylephrine or ephedrine, providing guidance for the most efficacious vasopressor when treating hypotension.Trial registrationData was collected from two protocols. The first was deemed to not require written, informed consent by the Institutional Review Board (IRB). The second was IRB-approved (Effect of Diastolic Dysfunction on Dynamic Cardiac Monitors) and registered on ClinicalTrials.gov (NCT04177225).

Evaluation of fluid responsiveness using liver compression in dogs with experimentally induced hypovolemia.

To investigate whether liver compression (LC) could increase stroke volume (SV) by more than 15% in healthy, anesthetized dogs with hypovolemia and suggest LC as a novel method to evaluate fluid responsiveness. 6 healthy Beagles. This prospective, nonrandomized experimental study was conducted from November 2023 to February 2024. The dogs were anesthetized with isoflurane and mechanically ventilated under neuromuscular blockade. After instrumentation, the dogs underwent the following 4 experimental stages in a sequential, nonrandomized manner: stage 1, baseline; stage 2, 30% withdrawal of circulating blood volume; stage 3, 50% infusion of the collected blood; and stage 4, the remaining 50% infusion of the collected blood. At each stage, SV via pulmonary artery thermodilution and hemodynamic variables were measured before, during, and after the LC. In stage 2, LC significantly increased mean SV by 30%, from 6.9 to 9 mL/beat. Simultaneously, LC significantly increased mean arterial pressure by 11 mm Hg and mean central venous pressure by 2 mm Hg, while pulse pressure variation significantly decreased from 28% to 22%. In stages 1, 3, and 4, LC did not significantly change mean SV, mean arterial pressure, and pulse pressure variation; however, mean central venous pressure significantly increased during stage 3. This study demonstrates that LC at 22 mm Hg for 1 minute could increase SV more than 15% in anesthetized, hypovolemic dogs and LC could be used as a novel method to evaluate fluid responsiveness.

Plethysmography Variation Index versus Pulse Pressure Variation as an Indicator of Fluid Responsiveness in Colorectal Surgeries during Immediate Postoperative Period

Abstract Objective Goal directed fluid therapy during major abdominal surgery may reduce postoperative morbidity. The Plethysmography Variability Index (PVI), derived from the pulse oximeter waveform, has been shown to be able to predict fluid responsiveness in a number of surgical circumstances. In this study, we will compare the effectiveness and re liability of Plethysmography variation index (PPV) and Pulse pressure variation (PPV) in prediction of fluid responsiveness in all sedated intubated mechanically ventilated patients admitted for postoperative resuscitation in our surgical ICU. Method 100 patients were placed in two different groups equally where heart rate, PPV, CI, and PVI were recorded on admission. Immediately after volume expansion is performed by infusing saline 500 ml over 30 mins and at the end of volume expansion PPV, CI, PVI will be recorded every 2 hours for the first 24 hours. Results Hundred patients aged from 18 to 64 years who were scheduled for colorectal surgery and were to be transferred to the intensive care unit for postoperative care for the f irst 24 hours post operatively who didn’t have any of the exclusion criteria were included in this prospective randomized comparative single blinded research. 100 patients were divided in to “responders” and “non responders”. Both groups received a volume 500 ml saline over 30 minutes immedietly postoperatively. Fluid responsiveness was tested in both groups using PVI (Plethysmography variability index) and PPV ( pulse pressure variation) using cardiac index as a reference parameter. PVI showed accurate fluid responsiveness in comparison with PPV in responders with mean ranging from ( (-6.66 ± 0.90) and (-5.89 ± 1.93) respectively, with a P-value<0.01 Conclusion This study revealed that after giving a fluid challenge of 500 ml of saline over 30 minutes, a rise in PVI and PPV was demonstrated using cardiac index as a reference for reliability for comparing the effectiveness and accuracy between PVI and PPV.comparing the effectiveness and accuracy between PVI and PPV.PVI and PVI and PPV PPV can be used can be used in assessment of fluid responsiveness of the intubated ventilated sedated patients in assessment of fluid responsiveness of the intubated ventilated sedated patients with sinus rhythm in ICU, and both methods can be performed at the bedside, but with sinus rhythm in ICU, and both methods can be performed at the bedside, but PVI has advantage of being continuousPVI has advantage of being continuous, operator independent, and more reliable, operator independent, and more reliable thanthan PPVPPV.

Comparing The Ratio Of Femoral Vein Diameter To Femoral Artery Diameter With Pulse Pressure Variation As A Diagnostic Tool For Fluid Responsiveness In Mechanically Ventilated Patient: A Prospective Observational Study

Background: There is a correlation between CVP and the femoral vein diameter. Therefore, we assessed the accuracy of the measurement using pulse pressure variation in patients on mechanical ventilation by measuring the ratio of femoral vein diameter to femoral artery diameter. Methods: We enrolled 60 patients with circulatory failure who were on mechanical ventilation (MV) in our clinical research. Two groups of patients were randomly assigned: Group (P): Thirty patients were placed on fully regulated mechanical ventilation, momentarily drugged, and paralyzed. At baseline, PPV is computed directly on Nihon Kohden monitors. Group (F): (n = 30), FVD/FAD ratio guided; The FVD/FAD ratio in our target group (F) was evaluated at baseline, The main outcome was the variation in MAP (mm Hg) following a three-hour infusion of liquids. Results: There was a statistically significant difference in mean arterial pressure (MAP) between before and after the patients received their fluids. MAP was 57.13 ± 2.46 before receiving the fluids, but it increased by an average of 20.60, p-value<0.001. Similarly, there was a statistically significant difference in the FVD/FAD ratio before and after the patients received their fluids. The mean FVD/FAD ratio was 0.91 ± 0.13 before receiving the fluids, but after the patients received their fluids, the mean FVD/FAD ratio was 1.27 ± 0.16 after receiving the fluids. Conclusion: The FVA/FAD ratio is a good indicator to assess the volume status of the patient who received fluids for resuscitation but should be confirmed by other parameters in hypovolemic-pre-resuscitated patients. Highlights • Assessement the accuracy of the measurement using pulse pressure variation in patients on mechanical ventilation • The state of blood volume can be determined using both invasive and non-invasive techniques. The FVA/FAD ratio is a good indicator to assess the volume status of the patient who received fluids for resuscitation.

Dynamic parameters of fluid responsiveness in the operating room : An analysis of intraoperative ventilation framework conditions.

Reliable assessment of fluid responsiveness with pulse pressure variation (PPV) depends on certain ventilation-related preconditions; however, some of these requirements are in contrast with recommendations for protective ventilation. The aim of this study was to evaluate the applicability of PPV in patients undergoing non-cardiac surgery by retrospectively analyzing intraoperative ventilation data. Intraoperative ventilation data from three large medical centers in Germany and Switzerland from January to December 2018 were extracted from electronic patient records and pseudonymized; 10,334 complete data sets were analyzed with respect to the ventilation parameters set as well as demographic and medical data. In 6.3% of the 3398 included anesthesia records, patients were ventilated with mean tidal volumes (mTV) > 8 ml/kg predicted body weight (PBW). These would qualify for PPV-based hemodynamic assessment, but the majority were ventilated with lower mTVs. In patients who underwent abdominal surgery (75.5% of analyzed cases), mTVs > 8 ml/kg PBW were used in 5.5% of cases, which did not differ between laparoscopic (44.9%) and open (55.1%) approaches. Other obstacles to the use of PPV, such as elevated positive end-expiratory pressure (PEEP) or increased respiratory rate, were also identified. Of all the cases 6.0% were ventilated with amTV of > 8 ml/kg PBW and aPEEP of 5-10 cmH2O and 0.3% were ventilated with amTV > 8 ml/kg PBW and aPEEP of > 10 cmH2O. The data suggest that only few patients meet the currently defined TV (of > 8 ml/kg PBW) for assessment of fluid responsiveness using PPV during surgery.

The Use of Pressure Recording Analytical Method in Patients Undergoing Endovascular Repair for Abdominal Aortic Aneurysm: The Impact on Clinical Decisions for the Appropriate Postoperative Setting and Cost-effective Analysis.

To analyze the use of the Pressure Recording Analytical Method (PRAM), an hemodynamic monitoring system, in evaluating intraoperative and postoperative hemodynamic instability in patients undergoing endovascular repair for abdominal aortic aneurysm, and to evaluate if the decision to refer patients to a ordinary ward or to a Cardiac Step-Down Unit (CSDU) after the intervention on the basis of intraoperative hemodynamic monitoring could be more cost-effective. After preoperative clinical evaluation, 44 patients were divided in this non-randomised study into two groups according to their postoperative destination: Group 1-ward (N=22) and Group 2-CSDU (N=22). All patients underwent monitoring with PRAM during the intervention and in the 24 postoperative hours, measuring several indices of myocardial contractility and other hemodynamic variables. According to the variability of two parameters, Stroke Volume Variation and Pulse Pressure Variation, patients were classified as stable or unstable. Unstable patients showed a significant alteration in several hemodynamic indices, in comparison to stable ones. According to the intraoperative monitoring, eight high risk patients could have been sent to an ordinary ward due to their stability, with a reduction in the improper use of CSDU and, consequently, in costs. Hemodynamic monitoring with PRAM can be useful in these patients, both for intraoperative management and for the choice of the more appropriate postoperative setting, possibly reducing the improper use of CSDU for hemodynamically stable patients who are judged to be at high risk preoperatively, and re-evaluating low surgical risk patients with an unstable intraoperative pattern, with a possible reduction in costs.

The Hemodynamic Changes Induced by Lung Recruitment Maneuver to Predict Fluid Responsiveness in Children during One Lung Ventilation-A Prospective Observational Study.

The prediction of fluid responsiveness in critical patients helps clinicians in decision making to avoid either under- or overloading of fluid. This study was designed to determine whether lung recruitment maneuver (LRM) would have an effect on the predictability of fluid responsiveness by the changes of hemodynamic parameters in pediatric patients who were receiving lung-protective ventilation and one-lung ventilation (OLV). A total of 34 children, aged 1-6 years old, scheduled for heart surgeries via right thoracotomy were enrolled. Patients were anesthetized and OLV with lung-protection ventilation settings was established, and then, positioned on left lateral decubitus. LRM and volume expansion (VE) were performed in sequence. Heart rate (HR), systolic arterial pressure (SAP), mean arterial pressure (MAP) diastolic arterial pressure (DAP), stroke volume (SV), stroke volume variation (SVV), and pulse pressure variation (PPV) were recorded via an A-line based monitor system at the following time points: before and after LRM (T1 and T2) and before and after VE (T3 and T4). An increase in stroke volume (SV) or mean arterial pressure (MAP) of ≥10% following fluid loading identified fluid responders. The predictability of fluid responsiveness by the changes of SV (ΔSVLRM) and MAP (ΔMAPLRM) after LRM and VE were statistically evaluated by receiver operating characteristic curves [area under the curves (AUC)]. SVs in all patients were significantly decreased after LRM (p < 0.01) and then, increased and returned to baseline after VE (p < 0.01). In total, 16 out of 34 patients who were fluid responders had significantly lower SV after LRM compared to that in fluid non-responders. The area under the receiver operating characteristic curves for ΔSVLRM was 0.828 (95% confidence interval [CI], 0.660 to 0.935; p < 0.001) and it indicated that ΔSVLRM was able to predict the fluid responsiveness of pediatric patients. MAPs in all patients were also decreased significantly after LRM, and 12 of them fell into the category of fluid responders after VE. Statistically, ΔMAPLRM did not predict fluid responsiveness when LRM was considered as an influential factor (p = 0.07). ΔSVLRM, but not ΔMAPLRM, showed great reliability in the prediction of the fluid responsiveness following VE in children during one-lung ventilation with lung-protective settings. ChiCTR2300070690.

Cardiac index-guided therapy to maintain optimised postinduction cardiac index in high-risk patients having major open abdominal surgery: the multicentre randomised iPEGASUS trial

BackgroundIt is unclear whether optimising intraoperative cardiac index can reduce postoperative complications. We tested the hypothesis that maintaining optimised postinduction cardiac index during and for the first 8 h after surgery reduces the incidence of a composite outcome of complications within 28 days after surgery compared with routine care in high-risk patients having elective major open abdominal surgery. MethodsIn three German and two Spanish centres, high-risk patients having elective major open abdominal surgery were randomised to cardiac index-guided therapy to maintain optimised postinduction cardiac index (cardiac index at which pulse pressure variation was <12%) during and for the first 8 h after surgery using intravenous fluids and dobutamine or to routine care. The primary outcome was the incidence of a composite outcome of moderate or severe complications within 28 days after surgery. ResultsWe analysed 318 of 380 enrolled subjects. The composite primary outcome occurred in 84 of 152 subjects (55%) assigned to cardiac index-guided therapy and in 77 of 166 subjects (46%) assigned to routine care (odds ratio: 1.87, 95% confidence interval: 1.03–3.39, P=0.038). Per-protocol analyses confirmed the results of the primary outcome analysis. ConclusionsMaintaining optimised postinduction cardiac index during and for the first 8 h after surgery did not reduce, and possibly increased, the incidence of a composite outcome of complications within 28 days after surgery compared with routine care in high-risk patients having elective major open abdominal surgery. Clinicians should not strive to maintain optimised postinduction cardiac index during and after surgery in expectation of reducing complications. Clinical trial registrationNCT03021525.

Hemodynamic changes in the prone position according to fluid loading after anaesthesia induction in patients undergoing lumbar spine surgery: a randomized, assessor-blind, prospective study

Introduction A change from the supine to prone position causes hemodynamic alterations. We aimed to evaluate the effect of fluid preloading in the supine position, the subsequent hemodynamic changes in the prone position and postoperative outcomes. Patients and methods This prospective, assessor-blind, randomized controlled trial was conducted between March and June 2023. Adults scheduled for elective orthopaedic lumbar surgery under general anaesthesia were enrolled. In total, 80 participants were randomly assigned to fluid maintenance (M) or loading (L) groups. Both groups were administered intravenous fluid at a rate of 2 ml/kg/h until surgical incision; Group L was loaded with an additional 5 ml/kg intravenous fluid for 10 min after anaesthesia induction. The primary outcome was incidence of hypotension before surgical incision. Secondary outcomes included differences in the mean blood pressure (mBP), heart rate, pleth variability index (PVi), stroke volume variation (SVV), pulse pressure variation (PPV), stroke volume index and cardiac index before surgical incision between the two groups. Additionally, postoperative complications until postoperative day 2 and postoperative hospital length of stay were investigated. Results Hypotension was prevalent in Group M before surgical incision and could be predicted by a baseline PVi >16. The mBP was significantly higher in Group L immediately after fluid loading. The PVi, SVV and PPV were lower in Group L after fluid loading, with continued differences at 2–3 time points for SVV and PPV. Other outcomes did not differ between the two groups. Conclusion Fluid loading after inducing general anaesthesia could reduce the occurrence of hypotension until surgical incision in patients scheduled for surgery in the prone position. Additionally, hypotension could be predicted in patients with a baseline PVi >16. Therefore, intravenous fluid loading is strongly recommended in patients with high baseline PVi to prevent hypotension after anaesthesia induction and in the prone position. Trial number KCT0008294 (date of registration: 16 March 2023)

Use of stepwise lung recruitment maneuver to predict fluid responsiveness under lung protective ventilation in the operating room

Recent research has revealed that hemodynamic changes caused by lung recruitment maneuvers (LRM) with continuous positive airway pressure can be used to identify fluid responders. We investigated the usefulness of stepwise LRM with increasing positive end-expiratory pressure and constant driving pressure for predicting fluid responsiveness in patients under lung protective ventilation (LPV). Forty-one patients under LPV were enrolled when PPV values were in a priori considered gray zone (4% to 17%). The FloTrac-Vigileo device measured stroke volume variation (SVV) and stroke volume (SV), while the patient monitor measured pulse pressure variation (PPV) before and at the end of stepwise LRM and before and 5 min after fluid challenge (6 ml/kg). Fluid responsiveness was defined as a ≥ 15% increase in the SV or SV index. Seventeen were fluid responders. The areas under the curve for the augmented values of PPV and SVV, as well as the decrease in SV by stepwise LRM to identify fluid responders, were 0.76 (95% confidence interval, 0.61–0.88), 0.78 (0.62–0.89), and 0.69 (0.53–0.82), respectively. The optimal cut-offs for the augmented values of PPV and SVV were > 18% and > 13%, respectively. Stepwise LRM -generated augmented PPV and SVV predicted fluid responsiveness under LPV.

Diagnostic accuracy of Plethysmographic Variability Index for the prediction of high pulse pressure variation in neurosurgery using a gray-zone approach: a retrospective study

Diagnostic accuracy of Plethysmographic Variability Index for the prediction of high pulse pressure variation in neurosurgery using a gray-zone approach: a retrospective study

Characterization and modeling of supercritical CO2 pulse pressures: Effects of activator mass and discharge plate thickness

Utilizing a bespoke CO2 phase transition pulse pressure experimental system, we conducted pulse pressure characterization tests across various activator masses, CO2 filling pressures, and energy discharge plate thicknesses. This approach enabled us to ascertain the pulse pressure's response characteristics and variation patterns under diverse conditions. The formula for calculating the peak supercritical CO2 pulse pressure was deduced by modeling the ultimate load calculation of the clamped circular plate, and then the time-course expression of the supercritical CO2 phase transition pulse pressure and energy was carried out by introducing the time factor and taking into account the parameters of the activator mass and the thickness of the energy discharging plate. Our findings reveal a four-stage pressure evolution in the cracking tube during initiation: a gradual increase, a rapid spike, swift attenuation, and eventual negative pressure formation. The activator mass and discharge plate thickness critically influence the peak pressure's timing and magnitude. Specifically, increased activator mass hastens peak pressure onset, while a thicker discharge plate amplifies it. The errors between calculated and experimental values for peak supercritical CO2 phase transition pressure fall within −5%–5%. Furthermore, the pressure peak and arrival time model demonstrates less than 10% error compared to experimental data, affirming its strong applicability. These insights offer theoretical guidance for controlling phase transition pressure and optimizing energy in supercritical CO2 systems.

Fluid therapy in ICU – A review

The most common indications of fluid resuscitation in critical care settings are severe hypovolemia, sepsis, trauma, burns, and perioperative fluid loss. Evaluation of intravascular volume status and the ability for identifying patients who might profit from volume expansion is vital. Traditional markers such as central venous pressure and pulmonary capillary wedge pressure have poor predictive value for fluid responsiveness. Dynamic indices such as pulse pressure variation, stroke volume variation, tidal volume challenge, and passive leg raise test are recommended to predict fluid responsiveness over static markers. The next perplexing part of fluid therapy is the choice of fluid resuscitation. The simplest answer is to provide crystalloids and avoid synthetic colloids (hydroxyethyl startch, gelatin, and dextran). Among the colloids, albumin has a role in certain clinical conditions in critical care settings. Between normal saline and buffered solutions, buffered solutions have the advantage of reducing acid–base disturbances, and chloride burden, and are likely to prevent renal failure. However, the advantage of buffered solutions did not consistently show up in large randomized controlled trials. Although administering fluids is a common therapeutic approach in critical care settings, administering fluids excessively has been linked to fatal outcomes. The resuscitation, optimization, stabilization, and evacuation concept describes the use of a dynamic fluid strategy to optimize benefits and prevent the negative effects of fluid overload. After receiving a patient in an emergency room or intensive care unit with hemodynamic instability, the first thing that comes to mind is whether or not the patient would benefit from fluid administration. How to predict fluid responsiveness? What type of fluids should be administered? When to stop administering fluids and start evacuation are vital questions confronted in day-to-day practice. In this article, we would like to discuss these issues and provide recommendations for current practices.

Comparison of Dynamic Measures in Intraoperative Goal-Directed Fluid Therapy of Patients with Morbid Obesity Undergoing Laparoscopic Sleeve Gastrectomy

IntroductionObesity increases the risk of morbidity and mortality during surgical procedures. Goal-directed fluid therapy (GDFT) is a new concept for perioperative fluid management that has been shown to improve patient prognosis. This study aimed to investigate the role of the Pleth Variability Index (PVI), systolic pressure variation (SPV), and pulse pressure variation (PPV) in maintaining tissue perfusion and renal function during GDFT management in patients undergoing laparoscopic sleeve gastrectomy (LSG).Materials and MethodsTwo hundred ten patients were enrolled in our prospective randomized controlled clinical trial. Demographic data, hemodynamic parameters, biochemical parameters, the amount of crystalloid and colloid fluid administered intraoperatively, and the technique of goal-directed fluid management used were recorded. Patients were randomly divided into three groups: PVI (n = 70), PPV (n = 70), and SPV (n = 70), according to the technique of goal-directed fluid management. Postoperative nausea and vomiting, time of return of bowel movement, and hospital stay duration were recorded.ResultsThere was no statistically significant difference between the number of crystalloids administered in all three groups. However, the amount of colloid administered was statistically significantly lower in the SPV group than in the PVI group, and there was no significant difference in the other groups. Statistically, there was no significant difference between the groups in plasma lactate, blood urea, and creatinine levels.ConclusionIn LSG, dynamic measurement techniques such as PVI, SPV, and PPV can be used in patients with morbid obesity without causing intraoperative and postoperative complications. PVI may be preferred over other invasive methods because it is noninvasive.Graphical abstract

Comparison between perfusion index, pleth variability index, and pulse pressure variability for prediction of hypotension during major abdominal surgery under general anaesthesia: A prospective observational study.

Short-term hypotension after general anaesthesia can negatively impact surgical outcomes. This study compared the predictive potential of the pleth variability index (PVI), pulse pressure variability (PPV), and perfusion index (PI) for anaesthesia-induced hypotension. This study's primary objective was to evaluate the predictive potential of PI, PVI, and PPV for hypotension. This observational study included 140 adult patients undergoing major abdominal surgery under general anaesthesia. Mean arterial pressure, heart rate, PVI, PPV, and PI were collected at 1-min intervals up to 20 min post anaesthesia induction. Hypotension was assessed at 5-min and 15-min intervals. Receiver operating characteristic (ROC) curves were plotted to determine the diagnostic performance and best cut-off for continuous variables in predicting a dichotomous outcome. Statistical significance was kept at P < 0.05. Hypotension prevalence within 5 and 15 min of anaesthesia induction was 36.4% and 45%, respectively. A PI cut-off of <3.5 had an area under the ROC curve (AUROC) of 0.647 (P = 0.004) for a 5-min hypotension prediction. The PVI's AUROC was 0.717 (P = 0.001) at cut-off >11.5, while PPV's AUROC was 0.742 (P = 0.001) at cut-off >12.5. At 15 min, PVI's AUROC was 0.615 (95% confidence interval 0.521-0.708, P = 0.020), with 54.9% positive predictive value and 65.2% negative predictive value. PVI, PPV, and PI predicted hypotension within 5 min after general anaesthesia induction. PVI had comparatively higher accuracy, sensitivity, specificity, and positive predictive value than PI and PPV when predicting hypotension at 15 min.

Pulse pressure variation guided goal-direct fluid therapy decreases postoperative complications in elderly patients undergoing laparoscopic radical resection of colorectal cancer: a randomized controlled trial

ObjectiveThe use of goal-directed fluid therapy (GDFT) has been shown to reduce complications and improve prognosis in high-risk abdominal surgery patients. However, the utilization of pulse pressure variation (PPV) guided GDFT in laparoscopic surgery remains a subject of debate. We hypothesized that utilizing PPV guidance for GDFT would optimize short-term prognosis in elderly patients undergoing laparoscopic radical resection for colorectal cancer compared to conventional fluid therapy.MethodsElderly patients undergoing laparoscopic radical resection of colorectal cancer were randomized to receive either PPV guided GDFT or conventional fluid therapy and explore whether PPV guided GDFT can optimize the short-term prognosis of elderly patients undergoing laparoscopic radical resection of colorectal cancer compared with conventional fluid therapy.ResultsThe incidence of complications was significantly lower in the PPV group compared to the control group (32.8% vs. 57.1%, P = .009). Additionally, the PPV group had a lower occurrence of gastrointestinal dysfunction (19.0% vs. 39.3%, P = .017) and postoperative pneumonia (8.6% vs. 23.2%, P = .033) than the control group.ConclusionUtilizing PPV as a monitoring index for GDFT can improve short-term prognosis in elderly patients undergoing laparoscopic radical resection of colorectal cancer.Registration numberChiCTR2300067361; date of registration: January 5, 2023.

Plethysmography variation index versus pulse pressure variation as an indicator of fluid responsiveness in colorectal surgeries during immediate postoperative period

ABSTRACT Background During major abdominal surgery, goal-directed fluid therapy may lessen postoperative morbidity. It has been demonstrated that the Plethysmography Variability Index (PVI), which is generated from the pulse oximeter waveform, can predict fluid responsiveness in a variety of surgical settings. Pulse pressure variation (PPV), one of the indicators of fluid responsiveness, has received the most research attention and clinical application of all the indicators. Through arterial cannulation, primarily the radial artery, pulse pressure fluctuation is recorded. The cyclic variations in intrathoracic pressure have less of an immediate impact on pulse pressure than they do on systolic pressure. In this study, sedated, intubated, mechanically ventilated patients admitted for postoperative resuscitation in our surgical ICU following colorectal surgeries had their fluid responsiveness assessed using the Plethysmography Variation Index (PVI) and the Pulse Pressure Variation (PPV) to compare their effectiveness and reliability.

Visual Evaluation of Plethysmographic Waveforms: Introducing the Simple Systolic Ratio as an Indicator of Fluid Responsiveness.

For patient safety, maintaining hemodynamic stability during surgical procedures is critical. Dynamic indices [such as systolic pressure variation (SPV) and pulse pressure variation (PPV)], have recently seen an increase in use. Given the risks associated with such invasive techniques, there is growing interest in non-invasive monitoring methods-and plethysmographic waveform analysis. However, many such non-invasive methods involve intricate calculations or brand-specific monitors. This study introduces the simple systolic ratio (SSR), derived from pulse oximetry tracings, as a non-invasive method to assess fluid responsiveness. This prospective observational study included 25 adult patients whose SPV, PPV, and SSR values were collected at 30-min intervals during open abdominal surgery. The SSR was defined as the ratio of the tallest waveform to the shortest waveform within pulse tracings. The correlations among SSR, SPV, and PPV were analyzed. Additionally, anaesthesia specialists visually assessed pulse oximetry tracings to determine fluid responsiveness using the SSR method. Strong correlations were observed between SSR and both SPV (r = 0.715, P < 0.001) and PPV (r = 0.702, P < 0.001). Receiver operator curve analysis identified optimal SSR thresholds for predicting fluid responsiveness at 1.47 for SPV and 1.50 for PPV. A survey of anaesthesia specialists using the SSR method to visually assess fluid responsiveness produced an accuracy rate of 83%. Based on the strong correlations it exhibits with traditional markers, SSR has great potential as a clinical tool, especially in resource-limited settings. However, further research is needed to establish its role, especially as it pertains to its universal applicability across monitoring devices.

A Novel Pre-Clinical Modeling of Massive Hemorrhagic Shock in Non-Human Primate: A Safe and Reproducible Method (Macaca fascicularis)

Although non-human primates are the closest animals to humans to simulate physiological and metabolic responses, there is a paucity of primate hemorrhagic shock models that are standardized and reproducible. Herein, we describe a model that is a clinical replica of extreme class IV hemorrhagic shock with a step-by-step description of the procedure in cynomolgus macaque monkeys. The physiological changes that occurred during the process were evaluated using hemodynamic parameters, echocardiogram, and laboratory values. Five female monkeys were subjected to trauma laparotomy, followed by cannulation of the abdominal aorta to achieve graded hemorrhage. A central line was placed in the right internal jugular vein, which was subsequently used for laboratory sampling and volume resuscitation. The withdrawal of blood was ceased when a predefined cardiac endpoint with cardiac arrhythmia or bradycardia was reached. The animals were then immediately resuscitated with transfusion. The primary cardiac endpoint was consistently reached in all 5 animals during the fourth hemorrhage when more than 70% of the estimated total blood volume was lost. No mortality occurred during the process. The blood pressure, cardiac output measured from an echocardiogram, and hemoglobin correlated well with increasing loss of circulating volume, whereas the pulse pressure variation did not. The echocardiogram was also a useful predictor for urgent volume replacement. This model offers a safe and reproducible surgical hemorrhagic model in non-human primates and simulates clinical practice. This could provide a useful platform on which further studies can be carried out to address unanswered questions in trauma management.