Volume Responsiveness Research Articles

The increase in cardiac output induced by a decrease in positive end-expiratory pressure reliably detects volume responsiveness: the PEEP-test study

BackgroundIn patients on mechanical ventilation, positive end-expiratory pressure (PEEP) can decrease cardiac output through a decrease in cardiac preload and/or an increase in right ventricular afterload. Increase in central blood volume by fluid administration or passive leg raising (PLR) may reverse these phenomena through an increase in cardiac preload and/or a reopening of closed lung microvessels. We hypothesized that a transient decrease in PEEP (PEEP-test) may be used as a test to detect volume responsiveness.MethodsMechanically ventilated patients with PEEP ≥ 10 cmH2O (“high level”) and without spontaneous breathing were prospectively included. Volume responsiveness was assessed by a positive PLR-test, defined as an increase in pulse-contour-derived cardiac index (CI) during PLR ≥ 10%. The PEEP-test consisted in reducing PEEP from the high level to 5 cmH2O for one minute. Pulse-contour-derived CI (PiCCO2) was monitored during PLR and the PEEP-test.ResultsWe enrolled 64 patients among whom 31 were volume responsive. The median increase in CI during PLR was 14% (11–16%). The median PEEP at baseline was 12 (10–15) cmH2O and the PEEP-test resulted in a median decrease in PEEP of 7 (5–10) cmH2O, without difference between volume responsive and unresponsive patients. Among volume responsive patients, the PEEP-test induced a significant increase in CI of 16% (12–20%) (from 2.4 ± 0.7 to 2.9 ± 0.9 L/min/m2, p < 0.0001) in comparison with volume unresponsive patients. In volume unresponsive patients, PLR and the PEEP-test increased CI by 2% (1–5%) and 6% (3–8%), respectively. Volume responsiveness was predicted by an increase in CI > 8.6% during the PEEP-test with a sensitivity of 96.8% (95% confidence interval (95%CI): 83.3–99.9%) and a specificity of 84.9% (95%CI 68.1–94.9%). The area under the receiver operating characteristic curve of the PEEP-test for detecting volume responsiveness was 0.94 (95%CI 0.85–0.98) (p < 0.0001 vs. 0.5). Spearman’s correlation coefficient between the changes in CI induced by PLR and the PEEP-test was 0.76 (95%CI 0.63–0.85, p < 0.0001).ConclusionsA CI increase > 8.6% during a PEEP-test, which consists in reducing PEEP to 5 cmH2O, reliably detects volume responsiveness in mechanically ventilated patients with a PEEP ≥ 10 cmH2O.Trial registration ClinicalTrial.gov (NCT 04,023,786). Registered July 18, 2019. Ethics Committee approval CPP Est III (N° 2018-A01599-46).

Effect of Goal-directed Fluid Therapy on Postoperative Cognitive Dysfunction in Elderly Patients Undergoing Combined Lingual and Cervical Radical Surgery

Background: The intraoperative rehydration technique known as the effect of Goal-Directed Fluid Therapy (GDFT), which is guided by the dynamic monitoring of volume responsiveness, has received a lot of attention recently. According to a meta-analysis by Bene, GDFT can maintain intraoperative hemodynamic stability, which lowers the incidence of postoperative complications and reduces stay at the intensive care unit. Objectives: This study aimed to determine how GDFT affected elderly patients who underwent combined lingual and cervical radical surgery after an operation for postoperative cognitive dysfunction (POCD). Methods: This interventional study was conducted between December 2021 and December 2022 in a medical center affiliated with Fujian Medical University on people undergoing radical neck and tongue surgery for tongue cancer. The samples (n=36) were selected using an availability sampling method and randomly divided into conventional fluid therapy (the Non-GDFT, n=18) and GDFT (n=18) groups. The Non-GDFT group was hydrated normally during anesthesia. A continuous infusion of 8 mL/(kg/h) of compounded sodium chloride was administered to the GDFT group to maintain basal hydration volume during the operation. Before and following surgery, Montreal Cognitive Assessment Scale scores were completed, arterial blood lactate values and bilateral cerebral oxygen saturation levels were measured at various times following the stabilization of anesthesia, and the levels of interleukin 6 (IL-6) and S100 protein in venous blood were calculated. Results: The Non-GDFT group had a higher incidence of POCD than the GDFT group, the GDFT group had significantly lower levels of IL-6 and S100 than the Non-GDFT group, the GDFT group had significantly lower levels of serum lactate than the Non-GDFT group. The GDFT group experienced significantly lower rates of intraoperative hypotensive and intraoperative low rSO2 events than the Non-GDFT group, and this difference was statistically significant (P&lt;0.05). Conclusion: Assuring the balance of cerebral oxygen supply and demand, lowering the production of inflammatory mediators, and successfully reducing the incidence of POCD are all possible benefits of GDFT.

Perioperative Fluid Management and Volume Assessment

Fluid therapy is an integral component of perioperative care and helps maintain or restore effective circulating blood volume. The principal goal of fluid management is to optimize cardiac preload, maximize stroke volume, and maintain adequate organ perfusion. Accurate assessment of volume status and volume responsiveness is necessary for appropriate and judicious utilization of fluid therapy. To accomplish this, static and dynamic indicators of fluid responsiveness have been widely studied. This review discusses the overarching goals of perioperative fluid management, reviews the physiology and parameters used to assess fluid responsiveness, and provides evidence-based recommendations on intraoperative fluid management.

Steuerung der Volumentherapie von Intensivpatienten: Neue Strategien und optimale Zielparameter?

Adequate therapy with intravenous fluids is crucial in the initial treatment of critically ill patients. Both hypovolemia and hypervolemia are associated with organ dysfunction and adverse outcomes. A recent international randomized trial investigated a restrictive volume management in comparison with a standard volume regimen. 90-day-mortality was not significantly reduced in the group with restrictive fluid administration. Instead of using a fixed fluid strategy - either restrictive or liberal - fluid therapy should be individualised: Adequate fluid application optimizes cardiac preload and tissue perfusion and avoids the harms of abundant volume therapy. Early use of vasopressors may facilitate the achievement of mean arterial pressure targets and minimize the risk of volume overload. Appropriate volume management requires evaluation of fluid status, knowledge of hemodynamic parameters and accurate testing of fluid responsiveness. Regarding the absence of evidence-based criterias and treatment goals for volume management in shock patients, an individualised approach resorting to diverse monitoring tools should be considered. UItrasound-based assessment of IVC diameter and echocardiography are excellent non-invasive tools to evaluate volume status. Passive leg raising (PLR) test represents a valid method for the assessment of volume responsiveness.

Rise and fall of CVP

The average blood pressure recorded in the superior vena cava near right atrium represents ‘central venous pressure’ (CVP). Traditionally CVP has been used as an indicator for predicting cardiac preload as well as volume responsiveness in critically ill patients. CVP is chiefly dependent on two factors: venous blood volume (venous return) and venous compliance. CVP is not an independent variable in determining cardiac output. Its relationship with cardiac output varies largely with the dynamic changes in the compliance of vascular compartment. The total blood volume in a venous system exists in two forms: Stressed volume (Vs) and Unstressed volume (Vu). The unstressed volume is equivalent to a basal blood volume that occupies the venous system. The stressed volume is the proportion that is dynamic in nature and affects the venous return and cardiac output. In this article, the basic physiology and applications of CVP as well as its limitations when compared to other dynamic parameters in assessing cardiovascular function are discussed.

Stroke Volume and Arterial Pressure Fluid Responsiveness in Patients With Elevated Stroke Volume Variation Undergoing Major Vascular Surgery: A Prospective Intervention Study

The identification of potential hemodynamic indicators to increase the predictive power of stroke-volume variation (SVV) for mean arterial pressure (MAP) and stroke volume (SV) fluid responsiveness. A prospective intervention study. At a single-center university hospital. Nineteen patients during major vascular surgery with 125 fluid interventions. When SVV ≥13% occurred for >30 seconds, 250 mL of Ringer's lactate were given within 2 minutes. Hemodynamic variables, such as pulse-pressure variation (PPV) and dynamic arterial elastance (Edyn), were measured by pulse power-wave analysis. The outcomes were MAP and SV responsiveness, defined as an increase of at least 10% of MAP and SV within 5 minutes of the fluid intervention. Of the fluid interventions, 48% were MAP-responsive, and 66% were SV-responsive. The addition of PPV and Edyn cut-off values to the SVV cut-off decreased sensitivity from 1-to-0.66 to-0.82, and concomitantly increased specificity from 0-to- 0.65-to-0.93 for the prediction of MAP and SV responsiveness in the authors' study setting. The areas under the receiver operating characteristic curves of PPV and Edyn for the prediction of MAP responsiveness were 0.79 and 0.75, respectively. The areas under the receiver operating characteristic curves for PPV and Edyn to predict SV responsiveness were 0.85 and 0.77, respectively. The PPV and Edyn showed good accuracy for the prediction of MAP and SV responsiveness in patients with elevated SVV during vascular surgery. Either PPV or Edyn may be used in conjunction with SVV to better predict MAP and SV fluid responsiveness in patients undergoing vascular surgery.

The role of pulse indicator continuous cardiac output (PiCCO) and critical care ultrasound in volume status assessment during fluid resuscitation for and prognosis of septic shock patients.

To investigate whether pulse index continuous cardiac output (PiCCO) and critical care ultrasound are highly consistent in volume status assessment during fluid resuscitation for septic shock patients and analyze their influence on the prognosis of septic shock. Eighty septic shock patients treated by Huizhou Central People's Hospital during December 2018 and December 2020 were included and divided into a study group and a control group by the presence of volume responsiveness, with each group having 40 patients. The control group was subject to PiCCO-guided fluid resuscitation therapy, while the study group was given fluid resuscitation therapy guided by critical care ultrasound. Cardiac output, cardiac function, and catheter-related infection (CRI) were documented for intergroup comparison to confirm whether these two techniques were consistent with each other regarding their effects on resuscitation for and prognosis of septic shock patients. Mechanical ventilation duration (MVD) and intensive care unit (ICU) length of stay (LoS) were significantly shorter in the study group when compared with the control group, and the differences were statistically significant (p<0.05, respectively). In terms of blood pressure parameters, the two groups did not differ greatly in diastolic blood pressure (DBP), mean arterial pressure (MAP), systolic blood pressure (SBP), and central venous pressure (CVP) before resuscitation (p>0.05, respectively); at 6h(six hour) after resuscitation, DBP, MAP, SBP, and CVP were substantially increased in both groups as compared with the pre-resuscitation levels (all p<0.05), but the differences between the two groups lacked statistical significance (all p>0.05). Comparing urine volume and degrees of positive fluid balance at 6 h and 12 h after resuscitation, drastic increases in urine volume and positive fluid balance were observed in both groups at 12 h as compared with at 6 h (all p<0.05); nevertheless, the two groups showed no statistically significant difference in urine volume and positive fluid balance at 6 h or 12 h (p>0.05, respectively). With regards to prognosis, there was no statistically significant difference between the two groups in the number of cases of continuous renal replacement therapy (CRRT), dosage of vasoactive agents and 28-d mortality rate (all p>0.05). However, the incidence of CRI was markedly lower in the study group (0/40) as compared with the control group (5/40), and the difference was statistically significant (p<0.05). Both PiCCO and critical care ultrasound can help achieve favorable outcomes from resuscitation for septic shock patients. Compared with PiCCO, critical care ultrasound monitoring appears to be more effective in preventing CRI and reducing MVD and ICU LoS, thereby easing patients' medical burden.

Central Venous Waveform Analysis and Cardiac Output in a Porcine Model of Endotoxemic Hypotension and Resuscitation.

Cardiac output (CO) is a valuable proxy for perfusion, and governs volume responsiveness during resuscitation from distributive shock. The underappreciated venous system has nuanced physiology that confers valuable hemodynamic information. In this investigation, deconvolution of the central venous waveform by the fast Fourier transformation (FFT) algorithm is performed to assess its ability to constitute a CO surrogate in a porcine model of endotoxemia-induced distributive hypotension and resuscitation. Ten pigs were anesthetized, catheterized, and intubated. A lipopolysaccharides infusion protocol was used to precipitate low systemic vascular resistance hypotension. Four crystalloid boluses (10 cc/kg) were then given in succession, after which heart rate, mean arterial pressure, thermodilution-derived CO, central venous pressure (CVP), and the central venous waveform were collected, the last undergoing fast Fourier transformation analysis. The amplitude of the fundamental frequency of the central venous waveform's cardiac wave (f0-CVP) was obtained. Heart rate, mean arterial pressure, CVP, f0-CVP, and CO were plotted over the course of the boluses to determine whether f0-CVP tracked with CO better than the vital signs, or than CVP itself. Distributive hypotension to a 25% mean arterial pressure decrement was achieved, with decreased systemic vascular resistance (mean 918 ± 227 [SD] dyne/s/cm-5 vs 685 ± 180 dyne/s/cm-5; p = 0.038). Full hemodynamic parameters characterizing this model were reported. Slopes of linear regression lines of heart rate, mean arterial pressure, CVP, f0-CVP, and CO were -2.8, 1.7, 1.8, 0.40, and 0.35, respectively, demonstrating that f0-CVP values closely track with CO over the 4-bolus range. Fast Fourier transformation analysis of the central venous waveform may allow real-time assessment of CO during resuscitation from distributive hypotension, possibly offering a venous-based approach to clinical estimation of volume responsiveness.

Central Venous Pressure Waveform Analysis Predicts Perfusion in a Porcine Model of Endotoxemic Hypotension and Resuscitation

Introduction: Cardiac output (CO), a proxy for perfusion, is a critical measure during sepsis and resuscitation. The understudied venous system has nuanced physiology that confers valuable information. In this investigation, deconvolution of the central venous pressure (CVP) waveform by the fast Fourier transformation (FFT) algorithm is performed to derive a CO surrogate in a “sepsis-like” porcine model of endotoxemic hypotension and resuscitation. Methods: Nine pigs were anesthetized, catheterized and intubated. A lipopolysaccharides infusion protocol was employed to precipitate low systemic vascular resistance (SVR) hypotension. Four subsequent crystalloid boluses (10 cc/kg) were given, after which thermodilution-CO, CVP and the CVP waveform were collected, the latter undergoing FFT analysis. The amplitude of the fundamental frequency of CVP waveform’s cardiac wave (“f0-CVP”) was obtained. Mean CVP, f0-CVP and CO were plotted over the course of the boluses to determine whether f0-CVP tracked with CO better than CVP itself. Results: Distributive hypotension to a 25% mean arterial pressure decrement was achieved, with decreased SVR (918±227 [standard deviation] dynes/seconds/cm-5 vs 685±180 dynes/seconds/cm-5; P = 0.038). Over four boluses, slopes of linear regression lines of CVP (r2=0.27; P < 0.001), f0-CVP (r2=0.15; P = 0.01) and CO (r2=0.08; P = 0.06) were 0.447, 0.148 and 0.178, respectively, demonstrating that f0-CVP constitutes a more accurate CO surrogate than CVP. Conclusion: FFT analysis of CVP waveforms offers a novel paradigm to interpret readily obtainable hemodynamic information. It offers potential for real-time utility in assessing volume responsiveness in sepsis and resuscitation, while further offering potential translation to the less-invasive peripheral venous pressure waveform.

Ability of PEEP induced lung-heart interaction to assess volume responsiveness in perioperative setting

Ability of PEEP induced lung-heart interaction to assess volume responsiveness in perioperative setting

Mid-regional plasma pro-atrial natriuretic peptide and stroke volume responsiveness for detecting deviations in central blood volume following major abdominal surgery.

BackgroundA reduced central blood volume is reflected by a decrease in mid‐regional plasma pro‐atrial natriuretic peptide (MR‐proANP), a stable precursor of ANP, and a volume deficit may also be assessed by the stroke volume (SV) response to head‐down tilt (HDT). We determined plasma MR‐proANP during major abdominal procedures and evaluated whether the patients were volume responsive by the end of the surgery, taking the fluid balance and the crystalloid/colloid ratio into account.MethodsPatients undergoing pancreatic (n = 25), liver (n = 25), or gastroesophageal (n = 38) surgery were included prospectively. Plasma MR‐proANP was determined before and after surgery, and the fluid response was assessed by the SV response to 10° HDT after the procedure. The fluid strategy was based mainly on lactated Ringer's solution for gastroesophageal procedures, while for pancreas and liver surgery, more human albumin 5% was administered.ResultsPlasma MR‐proANP decreased for patients undergoing gastroesophageal surgery (−9% [95% CI −3.2 to −15.3], p = .004) and 10 patients were fluid responsive by the end of surgery (∆SV > 10% during HDT) with an administered crystalloid/colloid ratio of 3.3 (fluid balance +1389 ± 452 ml). Furthermore, plasma MR‐proANP and fluid balance were correlated (r = .352 [95% CI 0.031–0.674], p < .001). In contrast, plasma MR‐proANP did not change significantly during pancreatic and liver surgery during which the crystalloid/colloid ratio was 1.0 (fluid balance +385 ± 478 ml) and 1.9 (fluid balance +513 ± 381 ml), respectively. For these patients, there was no correlation between plasma MR‐proANP and fluid balance, and no patient was fluid responsive.ConclusionPlasma MR‐proANP was reduced in fluid responsive patients by the end of surgery for the patients for whom the fluid strategy was based on more lactated Ringer's solution than human albumin 5%.

Correlation of carotid corrected flow time and respirophasic variation in blood flow peak velocity with stroke volume variation in elderly patients under general anaesthesia

BackgroundAccurate assessment of volume responsiveness in elderly patients is important as it may reduce the risk of post-operative complications and enhance surgical recovery. This study evaluated the utility of two Doppler ultrasound-derived parameters, the carotid corrected flow time (FTc) and respirophasic variation in carotid artery blood flow peak velocity (ΔVpeak), to predict volume responsiveness in elderly patients under general anaesthesia.MethodsA total of 97 elderly patients undergoing elective abdominal surgery under general anaesthesia were enrolled in this prospective observational study. After entering the operating room, all patients underwent radial artery puncture connected with a LiDCO device to measure stroke volume variation (SVV), and fluid therapy was performed after anaesthesia induction. Patients were classified as responders if SVV ≥ 13% before fluid challenge and nonresponders if SVV < 13%. The FTc, ΔVpeak, SVV and haemodynamic data were measured by ultrasound at baseline (T0) and before (T1) and after (T2) fluid challenge. The correlations between the Doppler ultrasound-derived parameters and SVV were analysed, and the receiver operating characteristic (ROC) curves was computed to characterize both FTc and ΔVpeak as measures of volume responsiveness in elderly patients.ResultsForty-one (42.3%) patients were fluid responders. Carotid FTc before fluid challenge was negatively correlated with SVV before fluid challenge (r = -0.77; P < 0.01), and ΔVpeak was positively correlated with SVV (r = 0.72; P < 0.01). FTc and ΔVpeak predicted SVV ≥ 13% after general anaesthesia in elderly patients, with areas under the receiver operating characteristic curves (AUROCs) of 0.811 [95% confidence interval (CI), 0.721–0.900; P < 0.001] and 0.781 (95% CI, 0.686–0.875; P < 0.001), respectively. The optimal cut-off values of FTc and ΔVpeak to predict SVV ≥ 13% were 340.74 ms (sensitivity of 76.8%; specificity of 80.5%) and 11.69% (sensitivity of 78.0%; specificity of 67.9%), respectively.ConclusionsThere was a good correlation between carotid artery ultrasound parameters and SVV. FTc predicted fluid responsiveness better than ΔVpeak in elderly patients during general anaesthesia. Further study is needed before these parameters can be recommended for clinical application.Trial registrationwww.chictr.org.cn(ChiCTR2000031193); registered 23 March 2020.

To identify normovolemia in humans: The stroke volume response to passive leg raising vs. head-down tilt.

Volume responsiveness can be evaluated by tilting maneuvers such as head‐down tilt (HDT) and passive leg raising (PLR), but the two procedures use different references (HDT the supine position; PLR the semi‐recumbent position). We tested whether the two procedures identify “normovolemia” by evaluating the stroke volume (SV) and cardiac output (CO) responses and whether the peripheral perfusion index (PPI) derived from pulse oximetry provides similar information. In randomized order, 10 healthy men were exposed to both HDT and PLR, and evaluations were made also when the subjects fasted. Central cardiovascular variables were derived by pulse contour analysis and changes in central blood volume assessed by thoracic electrical admittance (TEA). During HDT, SV remained stable (fasted 110 ± 16 vs. 109 ± 16 ml; control 113 ± 16 vs. 111 ± 16 ml, p > 0.05) with no change in CO, TEA, PPI, or SV variation (SVV). In contrast during PLR, SV increased (fasted 108 ± 17 vs. 117 ± 17 ml; control 108 ± 18 vs. 117 ± 18 ml, p < 0.05) followed by an increase in TEA (p < 0.05) and CO increased when subjects fasted (6.7 ± 1.5 vs. 7.1 ± 1.5, p = 0.007) with no change in PPI or SVV. In conclusion, SV has a maximal value for rest in supine men, while PLR restores SV as CBV is reduced in a semi‐recumbent position and the procedure thereby makes healthy volunteers seem fluid responsive.

Assessment of volume responsiveness by ultrasound parameters of carotid blood flow in patients with cardiogenic shock

Introduction There is no noninvasive method that can reliably and accurately identify fluid responsiveness. As such, in patients with undifferentiated shock, treatment often involves empiric fluid administration, in the hope that volume expansion will increase preload, which will then serve to increase cardiac output. However, for patients on the flat portion of the Starling curve, aggressive fluid administration results in no appreciable increase in cardiac output and may be detrimental to hemodynamically unstable patients. Objective The aim of this study was to compare the sensitivity and specificity of cardiac output measurement using bedside ultrasound on carotid artery and Transthoracic Echocardiogram(TTE) while assessing volume responsiveness in cardiogenic shock patients. Patients and methods In this prospective observational study, 40 cardiogenic shock patients were enrolled. Carotid artery Doppler ultrasound was performed where carotid blood flow (CBF) was calculated and TTE where cardiac output was calculated before and after passive leg-raising test to assess volume responsiveness. Results CBF measurements in comparison with cardiac output for assessment of fluid responsiveness had a sensitivity of 83.33% and specificity of 100%. Conclusion Carotid Doppler ultrasound and calculation of CBF is a reliable predictor to fluid responsiveness in patients with cardiogenic shock where transthoracic echocardiography is the gold standard in dynamic monitoring of the change in stroke volume after a maneuver that increases venous return (preload).

Respiratory-Cardiovascular Interactions During Mechanical Ventilation: Physiology and Clinical Implications.

Positive-pressure inspiration and positive end-expiratory pressure (PEEP) increase pleural, alveolar, lung transmural, and intra-abdominal pressure, which decrease right and left ventricular (RV; LV) preload and LV afterload and increase RV afterload. The magnitude and clinical significance of the resulting changes in ventricular function are determined by the delivered tidal volume, the total level of PEEP, the compliance of the lungs and chest wall, intravascular volume, baseline RV and LV function, and intra-abdominal pressure. In mechanically ventilated patients, the most important, adverse consequences of respiratory-cardiovascular interactions are a PEEP-induced reduction in cardiac output, systemic oxygen delivery, and blood pressure; RV dysfunction in patients with ARDS; and acute hemodynamic collapse in patients with pulmonary hypertension. On the other hand, the hemodynamic changes produced by respiratory-cardiovascular interactions can be beneficial when used to assess volume responsiveness in hypotensive patients and by reducing dyspnea and improving hypoxemia in patients with cardiogenic pulmonary edema. Thus, a thorough understanding of the physiological principles underlying respiratory-cardiovascular interactions is essential if critical care practitioners are to anticipate, recognize, manage, and utilize their hemodynamic effects. © 2022 American Physiological Society. Compr Physiol 12:1-24, 2022.

Changes in the Cardiac Index Induced by Unilateral Passive Leg Raising in Spontaneously Breathing Patients: A Novel Way to Assess Fluid Responsiveness.

BackgroundEvaluation of fluid responsiveness in intensive care unit (ICU) patients is crucial. This study was to determine whether changes in the cardiac index (CI) induced by a unilateral passive leg raising (PLR) test in spontaneously breathing patients can estimate fluid responsiveness.MethodsThis was a prospective study, and 40 patients with spontaneous breathing activity who were considered for volume expansion (VE) were included. CI data were obtained in a semirecumbent position, during unilateral PLR, bilateral PLR, and immediately after VE. If the CI increased more than 15% in response to the expansion in volume, patients were defined as responders.ResultsThe results showed that a unilateral PLR-triggered CI increment of ≥7.5% forecasted a fluid-triggered CI increment of ≥15% with 77.3% sensitivity and 83.3% specificity with and an area under the receiver operating characteristic (ROC) curve of 0.82 [P < 0.001]. Compared with that for bilateral PLR, the area under the ROC curve constructed for unilateral PLR-triggered changes in CI (ΔCI) was not significantly different (p = 0.1544).ConclusionΔCI >7.5% induced by unilateral PLR may be able to predict fluid responsiveness in spontaneously breathing patients and is not inferior to that induced by bilateral PLR.Trial RegistrationUnilateral passive leg raising test to assess patient volume responsiveness: Single-Center Clinical Study, ChiCTR2100046762. Registered May 28, 2021.

Goal-Directed Intraoperative Fluid Therapy Benefits Patients Undergoing Major Gynecologic Oncology Surgery: A Controlled Before-and-After Study.

BackgroundFluid management during major gynecologic oncology surgeries faces great challenges due to the distinctive characteristics of patients with gynecologic malignancies as well as features of the surgical procedure. Intraoperative goal-directed fluid therapy (GDFT) has been proven to be effective in reducing postoperative complications among major colorectal surgeries; however, the efficacy of GDFT has not been fully studied in gynecologic malignancy surgeries. This study aimed to discuss the influence of GDFT practice in patients undergoing major gynecologic oncology surgery.MethodsThis study was a controlled before-and-after study. From June 2015 to June 2018 in Peking Union Medical College Hospital, a total of 300 patients scheduled for elective laparotomy of gynecological malignancies were enrolled and chronologically allocated into two groups, with the earlier 150 patients in the control group and the latter 150 patients in the GDFT group. The GDFT protocol was applied by Vigileo/FloTrac monitoring of stroke volume and fluid responsiveness to guide intraoperative fluid infusion and the use of vasoactive agents. The primary outcome was postoperative complications within 30 days after surgery. The secondary outcome included length of stay and time of functional recovery.ResultsA total of 249 patients undergoing major gynecologic oncology surgery were analyzed in the study, with 129 in the control group and 120 patients in the GDFT group. Patients in the GDFT group had higher ASA classifications and more baseline comorbidities. GDFT patients received significantly less fluid infusion than the control group (15.8 vs. 17.9 ml/kg/h), while fluid loss was similar (6.9 vs. 7.1 ml/kg/h). GDFT was associated with decreased risk of postoperative complications (OR = 0.572, 95% CI 0.343 to 0.953, P = 0.032), especially surgical site infections (OR = 0.127, 95% CI 0.003 to 0.971, P = 0.037). The postoperative bowel function recovery and length of hospital stay were not significantly different between the two groups.ConclusionGoal-directed intraoperative fluid therapy is associated with fewer postoperative complications in patients undergoing major gynecologic oncology surgery.

Where Are We Heading With Fluid Responsiveness and Septic Shock?

When hypovolemia is left uncorrected, it can lead to poor tissue oxygenation and organ dysfunction. On the other hand, excessive fluid administration can increase the risk of complications. Assessing volume responsiveness in critically ill patients is therefore crucial. In this article we summarized the literature addressing the most sensitive and specific dynamic predictors for fluid responsiveness, to help clarify the best way to guide clinicians in managing patients with shock. Data were collected from PubMed and EMBASE of high-quality articles, randomized controlled trials (RCTs), retrospective research, and metanalyses; articles were identified from January 2000 to February 2021. We identified and critically reviewed the published peer-reviewed literature investigating the dynamic predictors to assess fluid responsiveness. Evidence suggests that the traditional use of static predictors for fluid responsiveness should be abandoned. Over the last 20 years, a number of dynamic tests have been developed. These tests are based on the principle of inducing short-term changes in cardiac preload using heart-lung interactions. However, in routine practice the conditions to meet the requirements of these dynamic parameters are frequently not met. Therefore, more dynamic predictors that do not depend on heart-lung interaction have developed such as the mini fluid challenge test and passive leg raising test These tests have fewer limitations and higher sensitivity and specificity compared to the other tests.

Influencing factors and countermeasures of pulse pressure variation in predicting volume responsiveness in patients with acute respiratory distress syndrome

脉压变异率（PPV）作为心肺交互的产物，是预测容量反应性的动态指标，但PPV预测急性呼吸窘迫综合征患者容量反应性受到诸多因素影响，如小潮气量通气、自主呼吸、腹内高压，此时可通过改变PPV阈值、潮气量挑战、叹息试验等方法提高其预测准确性；当PPV预测容量反应性准确性受到呼吸系统顺应性降低或右心功能不全影响时，则需要通过被动抬腿试验和呼气末阻断试验才能准确预测容量反应性。.

The diagnostic accuracy of inferior vena cava respiratory variation in predicting volume responsiveness in patients under different breathing status following abdominal surgery

BackgroundThe validation of inferior vena cava (IVC) respiratory variation for predicting volume responsiveness is still under debate, especially in spontaneously breathing patients. The present study aims to verify the effectiveness and accuracy of IVC variability for volume assessment in the patients after abdominal surgery under artificially or spontaneously breathing.MethodsA total of fifty-six patients after abdominal surgeries in the anesthesia intensive care unit ward were included. All patients received ultrasonographic examination before and after the fluid challenge of 5 ml/kg crystalloid within 15 min. The same measurements were performed when the patients were extubated. The IVC diameter, blood flow velocity–time integral of the left ventricular outflow tract, and cardiac output (CO) were recorded. Responders were defined as an increment in CO of 15% or more from baseline.ResultsThere were 33 (58.9%) mechanically ventilated patients and 22 (39.3%) spontaneously breathing patients responding to fluid resuscitation, respectively. The area under the curve was 0.80 (95% CI: 0.68–0.90) for the IVC dimeter variation (cIVC1) in mechanically ventilated patients, 0.87 (95% CI: 0.75–0.94) for the collapsibility of IVC (cIVC2), and 0.85 (95% CI: 0.73–0.93) for the minimum IVC diameter (IVCmin) in spontaneously breathing patients. The optimal cutoff value was 15.32% for cIVC1, 30.25% for cIVC2, and 1.14 cm for IVCmin. Furthermore, the gray zone for cIVC2 was 30.72 to 38.32% and included 23.2% of spontaneously breathing patients, while 17.01 to 25.93% for cIVC1 comprising 44.6% of mechanically ventilated patients. Multivariable logistic regression analysis indicated that cIVC was an independent predictor of volume assessment for patients after surgery irrespective of breathing modes.ConclusionIVC respiratory variation is validated in predicting patients' volume responsiveness after abdominal surgery irrespective of the respiratory modes. However, cIVC or IVCmin in spontaneously breathing patients was superior to cIVC in mechanically ventilated patients in terms of clinical utility, with few subjects in the gray zone for the volume responsiveness appraisal.Trial registrationChiCTR-INR-17013093. Initial registration date was 24/10/2017.