Comparison of vena cava distensibility index and pulse pressure variation for the evaluation of intravascular volume in critically ill children

Abstract Objective: In this study, the authors aimed to evaluate the effectiveness of the vena cava distensibility index and pulse pressure variation as dynamic parameters for estimating intravascular volume in critically ill children. Methods: Patients aged 1 month to 18 years, who were hospitalized in the present study's pediatric intensive care unit, were included in the study. The patients were divided into two groups according to central venous pressure: hypovolemic (< 8mmHg) and non-hypovolemic (central venous pressure ≥ 8 mmHg) groups. In both groups, vena cava distensibility index was measured using bedside ultrasound and pulse pressure variation. Measurements were recorded and evaluated under arterial monitoring. Results: In total, 19 (47.5%) of the 40 subjects included in the study were assigned to the central venous pressure ≥ 8 mmHg group, and 21 (52.5%) to the central venous pressure < 8 mmHg group. A moderate positive correlation was found between pulse pressure variation and vena cava distensibility index (r = 0.475, p < 0.01), while there were strong negative correlations of central venous pressure with pulse pressure variation and vena cava distensibility index (r = -0.628, p < 0.001 and r = -0.760, p < 0.001, respectively). In terms of predicting hypovolemia, the predictive power for vena cava distensibility index was > 16% (sensitivity, 90.5%; specificity, 94.7%) and that for pulse pressure variation was > 14% (sensitivity, 71.4%; specificity, 89.5%). Conclusion: Vena cava distensibility index has higher sensitivity and specificity than pulse pressure variation for estimating intravascular volume, along with the advantage of non-invasive bedside application.

Comparison of pulse pressure variation, stroke volume variation, and plethysmographic variability index in pediatric patients undergoing craniotomy / 北京大学学报(医学版)

OBJECTIVE@#To compare well-known preload dynamic parameters intraoperatively including stroke volume variation (SVV), pulse pressure variation (PPV), and plethysmographic variability index (PVI) in children who underwent craniotomy for epileptogenic lesion excision.@*METHODS@#A total of 30 children aged 0 to 14 years undergoing craniotomy for intracranial epileptogenic lesion excision were enrolled. During surgery, we measured PPV, SVV (measured by the Flotrac/Vigileo device), and PVI (measured by the Masimo Radical-7 monitor) simultaneously and continuously. Preload dynamic parameter measurements were collected at predefined steps: after induction of anesthesia, during opening the skull, intraoperative electroencephalogram monitoring, excision of epileptogenic lesion, skull closure, at the end of the operation. After exclusion of outliers, agreement among SVV, PPV, and PVI was assessed using repeated measures of Bland-Altman approach. The 4-quadrant and polar plot techniques were used to assess the trending ability among the changes in the three parameters.@*RESULTS@#The mean SVV, PPV, and PVI were 8%±2%, 10%±3%, and 15%±7%, respectively during surgery. We analyzed a total of 834 paired measurements (3 to 8 data sets for each phase per patient). Repeated measures Bland-Altman analysis identified a bias of -2.3 and 95% confidence intervals between -1.9 and -2.7 (95% limits of agreement between -6.0 and 1.5) between PPV and SVV, showing significant correlation at all periods. The bias between PPV and PVI was -5.0 with 95% limits of agreement between -20.5 and 10.5, and that between SVV and PVI was -7.5 with 95% limits of agreement between -22.7 and 7.8, both not showing significant correlation. Reflected by 4-quadrant plots, the con-cordance rates showing the trending ability between the changes in PPV and SVV, PPV and PVI, SVV and PVI were 88.6%, 50.4%, and 50.1%, respectively. The concordance rate between PPV and SVV was higher (92.7%) in children aged less than 3 years compared with those aged 3 and more than 3 years. The mean angular bias, radial limits of agreement, and angular concordance rate in the polar analysis were not clinically acceptable in the changes between arterial pressure waveform-based parameters and volume-based PVI (PPV vs. PVI: angular mean bias 8.4°, angular concordance rate 29.9%; SVV vs. PVI: angular mean bias 2.4°, angular concordance rate 29.1%). There was a high concordance between the two arterial pressure waveform-based parameters reflected by the polar plot (angular mean bias -0.22°, angular concordance rate 86.6%).@*CONCLUSION@#PPV can be viewed as a surrogate for SVV, especially in children aged less than 3 years. The agreement between arterial pressure waveform-based preload parameters (PPV and SVV) and PVI is poor and these two should not be considered interchangeable. Attempt to combine PVI and PPV for improving the anesthesiologist's ability to monitor cardiac preload in major pediatric surgery is warranted.

Plethysmographic variability index as a tool to assess fluid responsiveness in critically ill patients: a correlation study with inferior vena cava distensibility index

Background: In critically ill patients in the intensive care unit (ICU), early aggressive fluid replacement is the cornerstone of resuscitation. Traditionally employed static measures of fluid responsiveness have a poor predictive value. It is therefore imperative to employ dynamic measures of fluid responsiveness that take into account the heart lung interactions in the mechanically ventilated patients. The main objective of this study was to evaluate the reliability of one such non-invasive dynamic index: Plethysmographic variability index (PVI) compared to the widely employed Inferior vena cava distensibility index (dIVC).Methods: Seventy-six adult patients admitted at a tertiary care mixed ICU, who developed hypotension (MAP<65mmHg), were included in the study. PVI was recorded using the MASIMO-7 monitor and dIVC measurements done using Terason ultrasound. Based on the dIVC measurement threshold of 18%, the patients were classified into volume responders and non-responders. The hemodynamic, PVI and dIVC measurements were recorded at pre specified time points following a fluid challenge of 20 ml/kg crystalloid infusion.Results: Baseline PVI values were significantly higher in the responders (22.3±8.2) compared to non-responders (10.1±2.9) (p<0.001) and showed a declining trend at all time points in the responders. Similar declining trend was observed in the dIVC measurements. Overall, the Pearson correlation graph showed strong correlation between dIVC and PVI values at all time points (r=0.678, p=0.001). The ROC curve between the dIVC and PVI values revealed that Baseline PVI (Pre PVI) >15.5% discriminated between responders and non-responders with a 90.2% sensitivity and 75% specificity with an AUC of 0.84 (0.72-0.96) (p<0.001).Conclusions: There is good correlation between PVI values and measured dIVC values at baseline and following a fluid challenge. Thus, PVI may be an acceptable, real time, continuous, surrogate measure of fluid responsiveness in critically ill patients.

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

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

Enhanced recovery after surgery in liver resection: current concepts and controversies / 대한마취과학회지

Enhanced recovery after surgery (ERAS) attenuates the stress response to surgery in the perioperative period and hastens recovery. Liver resection is a complex surgical procedure where the enhanced recovery program has been shown to be safe and effective in terms of postoperative outcomes. ERAS programs have been shown to be associated with lower morbidity, shortened postoperative stay, and reduced cost with no difference in mortality and readmission rates. However, there are challenges that are unique to hepatic resection such as safety after epidural catheterization and postoperative coagulopathy, intraoperative fluids and postoperative organ dysfunction, need for low central venous pressure to reduce blood loss, and non-lactate containing intravenous fluids. This narrative review briefly discusses these concerns and controversies and suggests revisiting some of the strong recommendations made by the ERAS society in light of the recent evidence.

Mandatory criteria for the application of variability-based parameters of fluid responsiveness: a prospective study in different groups of ICU patients / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

BACKGROUND AND OBJECTIVE@#Stroke volume variation (SVV) has high sensitivity and specificity in predicting fluid responsiveness. However, sinus rhythm (SR) and controlled mechanical ventilation (CV) are mandatory for their application. Several studies suggest a limited applicability of SVV in intensive care unit (ICU) patients. We hypothesized that the applicability of SVV might be different over time and within certain subgroups of ICU patients. Therefore, we analysed the prevalence of SR and CV in ICU patients during the first 24 h of PiCCO-monitoring (primary endpoint) and during the total ICU stay. We also investigated the applicability of SVV in the subgroups of patients with sepsis, cirrhosis, and acute pancreatitis.@*METHODS@#The prevalence of SR and CV was documented immediately before 1241 thermodilution measurements in 88 patients.@*RESULTS@#In all measurements, SVV was applicable in about 24%. However, the applicability of SVV was time-dependent: the prevalence of both SR and CV was higher during the first 24 h compared to measurements thereafter (36.1% vs. 21.9%; P<0.001). Within different subgroups, the applicability during the first 24 h of monitoring ranged between 0% in acute pancreatitis, 25.5% in liver failure, and 48.9% in patients without pancreatitis, liver failure, pneumonia or sepsis.@*CONCLUSIONS@#The applicability of SVV in a predominantly medical ICU is only about 25%-35%. The prevalence of both mandatory criteria decreases over time during the ICU stay. Furthermore, the applicability is particularly low in patients with acute pancreatitis and liver failure.

Different predictabilities of volumetric response by pulse pressure variation in children after surgical re-pair of ventricular septal defect or tetralogy of Fallot / 实用医学杂志

Objective To compare the difference in pulse pressure variation(PPV)to predict volumetric response in children with ventricular septal defect(VSD)and tetralogy of Fallot(TOF). Methods VSD group consisted of 38 patients,aged 1.05 ± 0.75 years,while TOF group consisted of 36 patients,aged 1.15 ± 0.68 years. After separation from cardiopulmonary bypass,fluid infusion therapy was administered. PPV was recorded using pressure recording analytical method along with cardiac index(CI)before and after fluid infusion. Patients were considered as responders to fluid loading when CI increased ≥15%.Receiver operating characteristic(ROC) analysis was used to assess the accuracy and cutoffs of PPV to predict volumetric response.Results The PPV val-ues before and after fluid infusion were significantly lower in TOF group than that in VSD group(P < 0.01 for both).In VSD group,27 were responders and 11 nonresponders.ROC curve area was 0.89 and cutoff value 17.4%. In TOF group,26 were responders and 10 nonresponders.ROC curve area was 0.79 and cutoff value 13.4%.Con-clusion PPV is predictive of volumetric response in VSD and TOF patients following cardiac surgery.PPV's pre-dictivity and cutoff value are higher than the former. PPV is affected by right ventricle-pulmonary artery circula-tion,under-fluid infusion should be avoided in TOF due to lower PPV,over-fluid infusion should be avoided in VSD due to higher PPV.

Association between pulse pressure variation of radial artery and pulse pressure variation of dorsal pedal artery in neurosurgery operation / 临床麻醉学杂志

Objective To discuss the agreement between pulse pressure variation of radial artery and pulse pressure variation of dorsal pedalartery in neurosurgery.Methods Twenty-five patients undergoing selective craniotomy under general anesthesia were enrolled.The following data were monitored and recorded respectively after tracheal intubation general anesthesia under different time:radial artery pulse pressure variability (PPV1) and dorsalis pedis pulse pressure variation (PPV2).Tidal volume was set to 8 ml/kg.Bland-Altman plots were created to assess agreement between PPV1 and PPV2.Results The mean differences and the limits of agreement between PPV1 and PPV2 are 20 min after induction of anesthesia 0.5% (-1.9%-2.8%), boneless flap instantly-0.5% (-3.8%-2.9%), Cut the dura mater instantly-0.1% (-3.2%-3.0%), and bone flap 0.1% (-2.4%-2.6%).Conclusion Dorsal pedal artery pulse pressure variation in neurosurgery craniotomy has certain guiding significance to the monitoring and management.

Pulse pressure variation and stroke volume variation under different inhaled concentrations of isoflurane, sevoflurane and desflurane in pigs undergoing hemorrhage

OBJECTIVES: Inhalant anesthesia induces dose-dependent cardiovascular depression, but whether fluid responsiveness is differentially influenced by the inhalant agent and plasma volemia remains unknown. The aim of this study was to compare the effects of isoflurane, sevoflurane and desflurane on pulse pressure variation and stroke volume variation in pigs undergoing hemorrhage. METHODS: Twenty-five pigs were randomly anesthetized with isoflurane, sevoflurane or desflurane. Hemodynamic and echocardiographic data were registered sequentially at minimum alveolar concentrations of 1.00 (M1), 1.25 (M2), and 1.00 (M3). Then, following withdrawal of 30% of the estimated blood volume, these data were registered at a minimum alveolar concentrations of 1.00 (M4) and 1.25 (M5). RESULTS: The minimum alveolar concentration increase from 1.00 to 1.25 (M2) decreased the cardiac index and increased the central venous pressure, but only modest changes in mean arterial pressure, pulse pressure variation and stroke volume variation were observed in all groups from M1 to M2. A significant decrease in mean arterial pressure was only observed with desflurane. Following blood loss (M4), pulse pressure variation, stroke volume variation and central venous pressure increased (p <0.001) and mean arterial pressure decreased in all groups. Under hypovolemia, the cardiac index decreased with the increase of anesthesia depth in a similar manner in all groups. CONCLUSION: The effects of desflurane, sevoflurane and isoflurane on pulse pressure variation and stroke volume variation were not different during normovolemia or hypovolemia.

Continuous automatic pulse pressure variation: a systematic review and meta-analysis

The continuous automatic pulse pressure variation (PPVauto) is a test that continuously and automatically measures the pulse pressure of the patients who need fluid therapy among the general anesthesia patients or artificial respiration patients for whom voluntary breathing is impossible during surgical procedure. The objective of this review is to evaluate the safety and effectiveness of PPVauto. The searches were conducted on eight Korean databases including KoreaMed, Medline, Embase, and Cochrane Library. Seven hundred thirty-seven literatures were searched, and total of 20 studies were included for this review. On the basis of current data, we recommend that PPVauto is safe and effective test for patients who need fluid therapy among the general anesthesia patients or artificial respiration patients for whom voluntary breathing is impossible during surgical procedure.

Effect of positive end-expiratory pressure on functional hemodynamic parameters in patients in lateral position during operation / 解放军医学杂志

Objective To investigate the effect of positive end-expiratory pressure (PEEP) on functional hemodynamic parameters in patients lying in left lateral position during operation (right side total hip arthroplasty) under general anesthesia. Methods Twenty patients undergoing right side total hip arthroplasty lying in left lateral position under general anesthesia from March to August of 2013 were enrolled in the present study. The mechanical ventilation and PEEP were used in all of the patients, the functional hemodynamic parameters including stroke volume variation (SVV) and pulse pressure variation (PPV), and the circulatory parameters consisting of cardiac index (CI), mean arterial pressure (MAP) and heart rate (HR) under PEEP levels of 0cmH2O (P0), 4cmH2O (P4), 6cmH2O (P6), 8cmH2O (P8), 10cmH2O (P10), 12cmH2O (P12) and 14cmH2O (P14) were recorded. Results Along with the elevation of PEEP, SVV and PPV increased and exhibited a positive correlation with PEEP levels (r=0.507, r=0.359, P0.05). Conclusion The influence of PEEP on SVV and PPV must be considered when they are used to monitor volume status in order to avoid misjudgment of volume status.

GEDVI and PPV predict fluid responsiveness in patients with ALI secondary to septic shock / 中华急诊医学杂志

Objective To evaluate PICCO (pulse indicator continuous cardiac output) to predict fluid responsiveness in patients with acute lung injury secondary to septic shock.Methods We conducted a prospective study on 42 patients with acute lung injury secondary to septic shock.global end-diastolic volume index (GEDVI),pulse pressure variation (PPV),stroke volume variation (SVV),central vein pressure (CVP) and other haemodynamic data were recorded before and after fluid administration of 500 mL of 6％ hydroxyethyl starch.Responders were defined as patients with an increase in stroke volume index of at least 15％ after fluid loading.Performance of variables was analyzed using receiver operator characteristics analysis.Results GEDVI and PPV,but not SVV and CVP,were able to predict fluid responsiveness in patients with acute lung injury secondary to septic shock 1 hrs after admission to intensive care unit (ICU).The best area under the ROC curve (AUC) was found for GEDVI (AUC 0.802,P ＜0.01) and PPV (AUC 0.752,P ＜0.01) ; the optimal cut-off of GEDVI and PPV were 643.5 mL/m2 and 13.5％,respectively.At this cut point,the sensitivity was 90.9％,the specificity was 91.9％,however,only GEDVI was able to predict fluid responsiveness in patients with acute lung injury secondary to septic shock 6hrs afteradmission to ICU.The best area under the ROC curve (AUC) was found for GEDVI (AUC 0.788,P ＜ 0.01).the GEDVI ＜ 559 mL/m2 during loading were found to predict volume responsiveness with a sensitivity of 100％,specificity of 62.5％.Conclusions GEDVI and PPV predict fluid responsiveness in patients with acute lung injury secondary to septic shock in the early hours.

Effects of steep head-down position on pulse pressure variation

BACKGROUND: The effects of head-down position on dynamic hemodynamic variables remain without full understanding. We evaluated the effects of steep head-down position on the pulse pressure variation (PPV). METHODS: Forty patients were positioned at 30degrees head-down position after anesthesia induction. We measured the heart rate (HR), arterial blood pressure (BP) and PPV before and 2 minutes after the position change. RESULTS: PPV and HR decreased (9.3 +/- 3.2% to 4.6 +/- 1.8%, 67.2 +/- 11.4 to 62.4 +/- 7.8, respectively) after steep head-down position, whereas the BP increased. Baseline PPV was related with decreases of PPV (r2 = -0.83, P < 0.0001). An 8% PPV threshold discriminated the patients with more than 5% decreases of absolute PPV value. The area under the receiver operating characteristic curve was 0.98 (95% CI = 0.88 to 1.00, P < 0001). CONCLUSIONS: Steep head-down position caused decreases in PPV. Higher PPV at the supine position decreased more after the position change. Further investigations are required to assess the significance, the duration and the relationship with fluid responsiveness of this change.

Monitoring for fluid management: dynamic guides and fluid responsiveness

In the heart, ventricular end diastolic volume (EDV) before ejection (preload) is directly related to the amount of stroke volume. Generally, the filling pressures such as central venous pressure or pulmonary artery occlusion pressure are used as an indirect indicator of preload. Since cardiac compliance dose change, however, the filling pressure may not be an accurate indicator of the cardiac preload. As substitutes, volumetric parameters like right ventricular EDV or global end diastolic volume were developed and reported to be superior to the filling pressure in the assessment of preload. Preload responding volume resuscitation, however, is different according to the patient's condition. Whether any improvement is to be expected from volume resuscitation depends on whether the heart operates on the steep portion in its function curve. Under mechanical ventilation, because of the influence of positive pressure on vena caval and pulmonary venous return, arterial blood pressure and pulse pressure are maximum during inspiration and minimum a few heart-beats later, i.e., during the expiratory period. These periodic changes become prominent under the hypovolemic condition. Recently, various monitors continuously measuring pulse pressure variation (PPV) or stroke volume variation (SVV) using analysis of arterial wave is widely used as a dynamic guidance for volume resuscitation in mechanically ventilated patients. The ability of those variables to predict fluid responsiveness is better than those of filling pressure or EDV. Thus, PPV and SVV could be beneficially used to guide fluid therapy, while the safety limit of fluid therapy should be based on filling pressure.

Intraoperative fluid management in open gastrointestinal surgery: goal-directed versus restrictive

OBJECTIVE: The optimal strategy for fluid management during gastrointestinal surgery remains unclear. Minimizing the variation in arterial pulse pressure, which is induced by mechanical ventilation, is a potential strategy to improve postoperative outcomes. We tested this hypothesis in a prospective, randomized study with lactated Ringer's solution and 6% hydroxyethyl starch solution. METHOD: A total of 60 patients who were undergoing gastrointestinal surgery were randomized into a restrictive lactated Ringer's group (n = 20), a goal-directed lactated Ringer's group (n = 20) and a goal-directed hydroxyethyl starch group (n = 20). The goal-directed fluid treatment was guided by pulse pressure variation, which was recorded during surgery using a simple manual method with a Datex Ohmeda S/5 Monitor and minimized to 11% or less by volume loading with either lactated Ringer's solution or 6% hydroxyethyl starch solution (130/0.4). The postoperative flatus time, the length of hospital stay and the incidence of complications were recorded as endpoints. RESULTS: The goal-directed lactated Ringer's group received the greatest amount of total operative fluid compared with the two other groups. The flatus time and the length of hospital stay in the goal-directed hydroxyethyl starch group were shorter than those in the goal-directed lactated Ringer's group and the restrictive lactated Ringer's group. No significant differences were found in the postoperative complications among the three groups. CONCLUSION: Monitoring and minimizing pulse pressure variation by 6% hydroxyethyl starch solution (130/0.4) loading during gastrointestinal surgery improves postoperative outcomes and decreases the discharge time of patients who are graded American Society of Anesthesiologists physical status I/II.

Pulse pressure variation and prediction of fluid responsiveness in patients ventilated with low tidal volumes

OBJECTIVE: To determine the utility of pulse pressure variation (ΔRESP PP) in predicting fluid responsiveness in patients ventilated with low tidal volumes (V T) and to investigate whether a lower ΔRESP PP cut-off value should be used when patients are ventilated with low tidal volumes. METHOD: This cross-sectional observational study included 37 critically ill patients with acute circulatory failure who required fluid challenge. The patients were sedated and mechanically ventilated with a V T of 6-7 ml/kg ideal body weight, which was monitored with a pulmonary artery catheter and an arterial line. The mechanical ventilation and hemodynamic parameters, including ΔRESP PP, were measured before and after fluid challenge with 1,000 ml crystalloids or 500 ml colloids. Fluid responsiveness was defined as an increase in the cardiac index of at least 15%. ClinicalTrial.gov: NCT01569308. RESULTS: A total of 17 patients were classified as responders. Analysis of the area under the ROC curve (AUC) showed that the optimal cut-off point for ΔRESP PP to predict fluid responsiveness was 10% (AUC = 0.74). Adjustment of the ΔRESP PP to account for driving pressure did not improve the accuracy (AUC = 0.76). A ΔRESP PP>10% was a better predictor of fluid responsiveness than central venous pressure (AUC = 0.57) or pulmonary wedge pressure (AUC = 051). Of the 37 patients, 25 were in septic shock. The AUC for ΔRESP PP>10% to predict responsiveness in patients with septic shock was 0.484 (sensitivity, 78%; specificity, 93%). CONCLUSION: The parameter D RESP PP has limited value in predicting fluid responsiveness in patients who are ventilated with low tidal volumes, but a ΔRESP PP>10% is a significant improvement over static parameters. A ΔRESP PP > 10% may be particularly useful for identifying responders in patients with septic shock.

The Clinical Value of Pulse Pressure Variation to Monitor the Fluid Responsiveness and Effects of PEEP in Ventilated Patients with Acute Lung Injury / 中国呼吸与危重监护杂志

Objective To investigate whether pulse pressure variation (△PP) reflect the effects of PEEP and fluid resuscitation (FR) on hemodynamic effects.Methods Twenty critical patients with acute lung injury was ventilated with volume control (VT =8 mL/kg,Ti/Te = 1: 2) ,and PaCO2 was kept at 35 to 45 mm Hg.PEEP was setted as 5 cm H2O and 15 cm H2O in randomized order.Hemodynamic parameters including cardiac index, pulse pressure, central venous pressure, etc.were monitered by PiCCO system.Measurements were performed after the application of 5 cm H2O PEEP (PEEPs group)and 15 cm H2O PEEP (PEEP15 group) respectively.When the PEEP-induced decrease in cardiac index (CI) was > 10%, measurements were also performed after fluid resuscitation.Results Compared with PEEPs group, CI was decreased significantly in PEEP15 group(P < 0.05), and APP was increased significantly (P < 0.05).In 14 patients whose PEEP-induced decrease in CI was > 10%, fluid resuscitation increased CI from (3.01±0.57)L · min-1· m-1to (3.62±0.68)L · min-1 · m-2(P<0.01),and decreased △PP from (17±3)% to (10±2) % (P < 0.01).PEEP15-induced decrease in CI was correlated negatively with APP on PEEP5 (r =-0.91,P < 0.01) and with the PEEP15-induced increase in △PP (r =-0.79, P < 0.01).FR-induced changes in CI correlated with APP before FR (r = 0.96, P < 0.01) and with the FR-induced decrease in APP (r =-0.95, P < 0.01).Conclusions In ventilated patients with ALI, △PP may be a simple and useful parameter in predicting and assessing the hemodynamic effects of PEEP and FR.