Passive leg raising for predicting fluid responsiveness: a systematic review and meta-analysis

Purpose

We performed a systematic review and meta-analysis of studies investigating the passive leg raising (PLR)-induced changes in cardiac output (CO) and in arterial pulse pressure (PP) as predictors of fluid responsiveness in adults.

Methods

MEDLINE, EMBASE and Cochrane Database were screened for relevant original and review articles. The meta-analysis determined the pooled area under the ROC curve, the sensitivity, specificity and threshold for the PLR test when assessed with CO and PP.

Results

Twenty-one studies (991 adult patients, 995 fluid challenges) were included. CO was measured by echocardiography in six studies, calibrated pulse contour analysis in six studies, bioreactance in four studies, oesophageal Doppler in three studies, transpulmonary thermodilution or pulmonary artery catheter in one study and suprasternal Doppler in one study. The pooled correlation between the PLR-induced and the fluid-induced changes in CO was 0.76 (0.73–0.80). For the PLR-induced changes in CO, the pooled sensitivity was 0.85 (0.81–0.88) and the pooled specificity was 0.91 (0.88–0.93). The area under the ROC curve was 0.95 ± 0.01. The best threshold was a PLR-induced increase in CO ≥10 ± 2 %. For the PLR-induced changes in PP (8 studies, 432 fluid challenges), the pooled sensitivity was 0.56 (0.49–0.53), the pooled specificity was 0.83 (0.77–0.88) and the pooled area under the ROC curve was 0.77 ± 0.05. Sensitivity and subgroup analysis were consistent with the primary analysis.

Conclusions

PLR-induced changes in CO very reliably predict the response of CO to volume expansion in adults with acute circulatory failure. When PLR effects are assessed by changes in PP, the specificity of the PLR test remains acceptable but its sensitivity is poor.

     

End-tidal carbon dioxide is better than arterial pressure for predicting volume responsiveness by the passive leg raising test

Purpose

In stable ventilatory and metabolic conditions, changes in end-tidal carbon dioxide (EtCO₂) might reflect changes in cardiac index (CI). We tested whether EtCO₂ detects changes in CI induced by volume expansion and whether changes in EtCO₂ during passive leg raising (PLR) predict fluid responsiveness. We compared EtCO₂ and arterial pulse pressure for this purpose.

Methods

We included 65 patients [Simplified Acute Physiology Score (SAPS)?II?=?57?±?19, 37 males, under mechanical ventilation without spontaneous breathing, 15?% with chronic obstructive pulmonary disease, baseline CI?=?2.9?±?1.1?L/min/m²] in whom a fluid challenge was decided due to circulatory failure and who were monitored by an expiratory-CO₂ sensor and a PiCCO2 device. In all patients, we measured arterial pressure, EtCO₂, and CI before and after a fluid challenge. In 40 patients, PLR was performed before fluid administration. The PLR-induced changes in arterial pressure, EtCO₂, and CI were recorded.

Results

Considering the whole population, the fluid-induced changes in EtCO₂ and CI were correlated (r ²?=?0.45, p?=?0.0001). Considering the 40 patients in whom PLR was performed, volume expansion increased CI ??15?% in 21 ??volume responders.?? A PLR-induced increase in EtCO₂ ??5?% predicted a fluid-induced increase in CI ??15?% with sensitivity of 71?% (95?% confidence interval: 48?C89?%) and specificity of 100 (82?C100)?%. The prediction ability of the PLR-induced changes in CI was not different. The area under the receiver-operating characteristic (ROC) curve for the PLR-induced changes in pulse pressure was not significantly different from 0.5.

Conclusion

The changes in EtCO₂ induced by a PLR test predicted fluid responsiveness with reliability, while the changes in arterial pulse pressure did not.     

Prediction of fluid responsiveness in severe preeclamptic patients with oliguria

Purpose

Because severe preeclampsia (SP) may be associated with acute pulmonary oedema, fluid responsiveness needs to be accurately predicted. Passive leg raising (PLR) predicts fluid responsiveness. PLR has never been reported during pregnancy. Our first aim was to determine the percentage of SP patients with oliguria increasing their stroke volume after fluid challenge. Our second aim was to assess the accuracy of PLR to predict fluid responsiveness in those patients.

Methods

Patients with SP were prospectively included in the study. In the subgroup developing oliguria, transthoracic echocardiography was performed at baseline, during PLR and after a 500 ml fluid infusion over 15 min. Fluid responders were defined by a 15 % increase of stroke volume index. Five consecutive measurements were averaged for all parameters.

Results

Twenty-three (56 %) out of 41 patients with SP developed oliguria, 12 (52 %) out of these 23 responded to fluid challenge. During PLR, an increase of the velocity time integral of subaortic blood flow (ΔVTI) above 12 % predicted the response with a sensitivity and specificity of 75 [95 % confident interval (CI): 0.42–0.95] and 100 % (95 % CI: 0.72–1.00), respectively. An algorithm combining ΔVTI and the baseline value of VTI predicted fluid responsiveness with a sensitivity and specificity of 100 % (95 % CI: 0.74–1.00) and (95 % CI: 0.75–1.00). Urine output and respiratory variations of inferior vena cava diameter did not predict fluid responsiveness.

Conclusions

Only 52 % of oliguric patients were responders. PLR accurately predicts fluid responsiveness in the specific setting of SP. This noninvasive test should be tested in future algorithms for the management of SP.     

Central venous pressure measurements improve the accuracy of leg raising-induced change in pulse pressure to predict fluid responsiveness

Purpose  

Passive leg raising (PLR) is a maneuver performed to test the cardiac Frank-Starling mechanism. We assessed the influence of PLR-induced changes in preload on the performance of PLR-induced change in pulse pressure (Δ_PLRPP) and cardiac output (Δ_PLRCO) for fluid responsiveness prediction.     

Ability of pleth variability index to detect hemodynamic changes induced by passive leg raising in spontaneously breathing volunteers

Introduction

Pleth Variability Index (PVI) is a new algorithm that allows continuous and automatic estimation of respiratory variations in the pulse oximeter waveform amplitude. Our aim was to test its ability to detect changes in preload induced by passive leg raising (PLR) in spontaneously breathing volunteers.

Methods

We conducted a prospective observational study. Twenty-five spontaneously breathing volunteers were enrolled. PVI, heart rate and noninvasive arterial pressure were recorded. Cardiac output was assessed using transthoracic echocardiography. Volunteers were studied in three successive positions: baseline (semirecumbent position); after PLR of 45° with the trunk lowered in the supine position; and back in the semirecubent position.

Results

We observed significant changes in cardiac output and PVI during changes in body position. In particular, PVI decreased significantly from baseline to PLR (from 21.5 ± 8.0% to 18.3 ± 9.4%; P < 0.05) and increased significantly from PLR to the semirecumbent position (from 18.3 ± 9.4% to 25.4 ± 10.6 %; P < 0.05). A threshold PVI value above 19% was a weak but significant predictor of response to PLR (sensitivity 82%, specificity 57%, area under the receiver operating characteristic curve 0.734 ± 0.101).

Conclusion

PVI can detect haemodynamic changes induced by PLR in spontaneously breathing volunteers. However, we found that PVI was a weak predictor of fluid responsiveness in this setting.     

Respiratory variations in aortic blood flow predict fluid responsiveness in ventilated children

Objective

To investigate whether respiratory variations in aortic blood flow velocity (ΔVpeak ao), systolic arterial pressure (ΔPS) and pulse pressure (ΔPP) could accurately predict fluid responsiveness in ventilated children.

Design and setting

Prospective study in a 18-bed pediatric intensive care unit.

Patients

Twenty-six children [median age 28.5 (16–44) months] with preserved left ventricular (LV) function.

Intervention

Standardized volume expansion (VE).

Measurements and main results

Analysis of aortic blood flow by transthoracic pulsed-Doppler allowed LV stroke volume measurement and on-line ΔVpeak ao calculation. The VE-induced increase in LV stroke volume was >?15% in 18 patients (responders) and p?=?0.001], whereas ΔPP and ΔPS did not significantly differ between groups. The prediction of fluid responsiveness was higher with ΔVpeak ao [ROC curve area 0.85 (95% IC 0.99–1.8), p?=?0.001] than with ΔPS (0.64) or ΔPP (0.59). The best cut-off for ΔVpeak ao was 12%, with sensitivity, specificity, and positive and negative predictive values of 81.2%, 85.7%, 93% and 66.6%, respectively. A positive linear correlation was found between baseline ΔVpeak ao and VE-induced gain in stroke volume (rho?=?0.68, p?=?0.001).

Conclusions

While respiratory variations in aortic blood flow velocity measured by pulsed Doppler before VE accurately predict the effects of VE, ΔPS and ΔPP are of little value in ventilated children.

     

Preoperative evaluation of myometrial invasion in endometrial carcinoma: diagnostic performance of 3T MRI

Purpose

To evaluate the diagnostic accuracy of 3T MRI in preoperative staging of myometrial invasion.

Methods

Twenty-eight women with histological diagnosis of endometrial carcinoma were included in this prospective study. After T2-W SS-TSE and DWI, dynamic series of T1-W THRIVE images were obtained (0–180 s) followed by a T1-W THRIVE sequence in the late phase (5th min). For detection of deep myometrial infiltration: sensitivity, specificity, PPV, NPV, and accuracy were calculated on T2-W, postcontrast early arterial and late phase T1-W, and DWI. For the quantitative analysis of DWI, ADC values of the tumor were calculated and correlated with histologic grade. For the quantitative evaluation of dynamic series, SI-time curves were obtained and the maximum relative enhancement, wash-in rate, time-to-peak, and wash-out rate of masses and myometrium were compared.

Results

T2-W and early phase contrast-enhanced sequences obtained sensitivity 100 %, specificity 76 %, PPV 58 %, NPV 100 %, and accuracy 82 %; late-phase contrast-enhanced images obtained sensitivity 100 %, specificity 81 %, PPV 64 %, NPV 100 %, and accuracy 86 %; DWI obtained lower accuracy [sensitivity 71 %, specificity 62 %, PPV 38 %, NPV 87 %, and accuary 57 %] than T2-W and postcontrast images. The MRE of carcinomas were significantly lower than those of the myometrium. This analysis showed a significant improvement in tumor versus myometrium contrast during the late phase. On DWI, the mean ADC value of tumor was 1.02 ± 0.48 × 10^?3. There was no statistically significant correlation between tumor grades and ADCs.

Conclusions

As the 3T MRI scanner allows high-resolution images, accurate assessment of myometrial infiltration can be done especially with postcontrast late phase images.     

Passive leg raising as an indicator of fluid responsiveness in patients with severe sepsis

BACKGROUND:

In the management of critically ill patients, the assessment of volume responsiveness and the decision to administer a fluid bolus constitute a common dilemma for physicians. Static indices of cardiac preload are poor predictors of volume responsiveness. Passive leg raising (PLR) mimics an endogenous volume expansion (VE) that can be used to predict fluid responsiveness. This study was to assess the changes in stroke volume index (SVI) induced by PLR as an indicator of fluid responsiveness in mechanically ventilated patients with severe sepsis.

METHODS:

This was a prospective study. Thirty-two mechanically ventilated patients with severe sepsis were admitted for VE in ICU of the First Affiliated Hospital, Zhejiang University School of Medicine and Ningbo Medical Treatment Center Lihuili Hospital from May 2010 to December 2011. Patients with non-sinus rhythm or arrhythmia, parturients, and amputation of the lower limbs were excluded. Measurements of SVI were obtained in a semi-recumbent position (baseline) and during PLR by the technique of pulse indicator continuous cardiac output (PiCCO) system prior to VE. Measurements were repeated after VE (500 mL 6% hydroxyethyl starch infusion within 30 minutes) to classify patients as either volume responders or non-responders based on their changes in stroke volume index (ΔSVI) over 15%. Heart rate (HR), systolic artery blood pressure (ABPs), diastolic artery blood pressure (ABPd), mean arterial blood pressure (ABPm), mean central venous pressure (CVPm) and cardiac index (CI) were compared between the two groups. The changes of ABPs, ABPm, CVPm, and SVI after PLR and VE were compared with the indices at the baseline. The ROC curve was drawn to evaluate the value of ΔSVI and the change of CVPm (ΔCVPm) in predicting volume responsiveness. SPSS 17.0 software was used for statistical analysis.

RESULTS:

Among the 32 patients, 22 were responders and 10 were non-responders. After PLR among the responders, some hemodynamic variables (including ABPs, ABPd, ABPm and CVPm) were significantly elevated (101.2±17.6 vs.118.6±23.7, P=0.03; 52.8±10.7 vs. 64.8±10.7, P=0.006; 68.3±11.7 vs. 81.9±14.4, P=0.008; 6.8±3.2 vs. 11.9±4.0, P=0.001). After PLR, the area under curve (AUC) and the ROC curve of ΔSVI and ΔCVPm for predicting the responsiveness after VE were 0.882±0.061 (95%CI 0.759–1.000) and 0.805±0.079 (95%CI 0.650–0.959) when the cut-off levels of ΔSVI and ΔCVPm were 8.8% and 12.7%, the sensitivities were 72.7% and 72.7%, and the specificities were 80% and 80%.

CONCLUSION:

Changes in ΔSVI and ΔCVPm induced by PLR are accurate indices for predicting fluid responsiveness in mechanically ventilated patients with severe sepsis.KEY WORDS: Passive leg raising, Volume resuscitation, Hemodynamic monitoring, Stroke volume index, Central venous pressure, Severe sepsis, Fluid responsiveness, ROC curve     

Assessment of articular disc displacement of temporomandibular joint with ultrasound

Purpose

To assess pattern of articular disc displacement in patients with internal derangement (ID) of temporomandibular joint (TMJ) with ultrasound.

Materials and methods

Prospective study was conducted upon 40 TMJ of 20 patients (3 male, 17 female with mean age of 26.1 years) with ID of TMJ. They underwent high-resolution ultrasound and MR imaging of TMJ. The MR images were used as the gold standard for calculating sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR), and negative likelihood ratio (NLR) of ultrasound for diagnosis of anterior or sideway displacement of the disc.

Results

The anterior displaced disc was seen in 26 joints at MR and 22 joints at ultrasound. The diagnostic efficacy of ultrasound for anterior displacement has sensitivity of 79.3 %, specificity of 72.7 %, accuracy of 77.5 %, PPV of 88.5 %, NPV of 57.1 %, PLR of 2.9 and NLR of 0.34. The sideway displacement of disc was seen in four joints at MR and three joints at ultrasound. The diagnostic efficacy of ultrasound for sideway displacement has a sensitivity of 75 %, specificity of 63.6 %, accuracy of 66.7 %, PPV of 42.8, NPV of 87.5 %, PLR of 2.06, and NLR of 0.39.

Conclusion

We concluded that ultrasound is a non-invasive imaging modality used for assessment of anterior and sideway displacement of the articular disc in patients with ID of TMJ.     

Diagnostic ability of 99mTc-HSA-DTPA scintigraphy in combination with SPECT/CT for gastrointestinal bleeding

Purpose

Gastrointestinal (GI) bleeding scintigraphy in combination with single-photon emission computed tomography/computed tomography (SPECT/CT) remains to be studied in detail. This study aimed to examine the diagnostic ability of this tool.

Methods

GI bleeding scintigraphy using ^99mTc-human serum albumin-diethylenetriaminepentaacetic acid was performed for 38 patients with suspected GI bleeding. Twenty-four patients were diagnosed using planar images alone (planar group) and 14 patients were diagnosed using planar images and additional SPECT/CT images (planar + SPECT/CT group). The diagnostic ability of each method was analyzed.

Results

GI bleeding was observed in 20 of the 38 patients. For the existence of GI bleeding, planar images alone showed a sensitivity of 70%, specificity of 93%, positive predictive value (PPV) of 88%, negative predictive value (NPV) of 81%, and an overall accuracy of 83%, whereas planar images + SPECT/CT showed a sensitivity of 100%, specificity of 75%, PPV of 91%, NPV of 100%, and an overall accuracy of 93%. The source of bleeding was accurately diagnosed in 50% in the planar group and 78% in the planar + SPECT/CT group. In the planar + SPECT/CT group, 44% of the evaluable patients showed correct localization of the source of GI bleeding by additional SPECT/CT images, although planar images only showed incorrect localization.

Conclusion

GI bleeding scintigraphy in combination with SPECT/CT is a noninvasive and useful tool for the examination of GI bleeding.     

Accuracy of MDCT in the preoperative definition of Peritoneal Cancer Index (PCI) in patients with advanced ovarian cancer who underwent peritonectomy and hyperthermic intraperitoneal chemotherapy (HIPEC)

Purpose

To evaluate the accuracy of MDCT in the preoperative definition of Peritoneal Cancer Index (PCI) in patients with advanced ovarian cancer who underwent a peritonectomy and hyperthermic intraperitoneal chemotherapy (HIPEC) after neoadjuvant chemotherapy to obtain a pre-surgery prognostic evaluation and a prediction of optimal cytoreduction surgery.

Materials and methods

Pre-HIPEC CT examinations of 43 patients with advanced ovarian cancer after neoadjuvant chemotherapy were analyzed by two radiologists. The PCI was scored according to the Sugarbaker classification, based on lesion size and distribution. The results were compared with macroscopic and histologic data after peritonectomy and HIPEC. To evaluate the accuracy of MDCT to detect and localize peritoneal carcinomatosis, both patient-level and regional-level analyses were conducted. A correlation between PCI CT and histologic values for each patient was searched according to the PCI grading.

Results

Considering the patient-level analysis, CT shows a sensitivity, specificity, PPV, NPV, and an accuracy in detecting the peritoneal carcinomatosis of 100 %, 40 %, 93 % 100 %, and 93 %, respectively. Considering the regional level analysis, a sensitivity, specificity, PPV, NPV, and diagnostic accuracy of 72 %, 80 %, 66 %, 84 %, and 77 %, respectively were obtained for the correlation between CT and histology.

Conclusion

Our results encourage the use of MDCT as the only technique sufficient to select patients with peritoneal carcinomatosis for cytoreductive surgery and HIPEC on the condition that a CT examination will be performed using a dedicated protocol optimized to detect minimal peritoneal disease and CT images will be analyzed by an experienced reader.     

Jugular vein distensibility predicts fluid responsiveness in septic patients

Introduction

The purpose of the study was to verify the efficacy of using internal jugular vein (IJV) size and distensibility as a reliable index of fluid responsiveness in mechanically ventilated patients with sepsis.

Methods

Hemodynamic data of mechanically ventilated patients with sepsis were collected through a radial arterial indwelling catheter connected to continuous hemodynamic monitoring system (Most Care®, Vytech Health, Padova, Italy), including cardiac index (CI) (L/min/M²), heart rate (beats/min), mean arterial pressure (MAP) (mmHg), central venous pressure (CVP) (mmHg) and arterial pulse pressure variation (PPV), coupled with ultrasound evaluation of IJV distensibility (%), defined as a ratio of the difference between IJV maximal antero-posterior diameter during inspiration and minimum expiratory diameter to minimum expiratory diameter x100. Patients were retrospectively divided into two groups; fluid responders (R), if CI increase of more than or equal to 15% after a 7 ml/kg crystalloid infusion, and non-responders (NR) if CI increased more than 15%. We compared differences in measured variables between R and NR groups and calculated receiver-operator-characteristic (ROC) curves of optimal IJV distensibility and PPV sensitivity and specificity to predicting R. We also calculated a combined inferior vena cava distensibility-PPV ROC curve to predict R.

Results

We enrolled 50 patients, of these, 30 were R. Responders presented higher IJV distensibility and PPV before fluid challenge than NR (P <0.05). An IJV distensibility more than 18% prior to volume challenge had an 80% sensitivity and 85% specificity to predict R. Pairwise comparison between IJV distensibility and PPV ROC curves revealed similar ROC area under the curve results. Interestingly, combining IJV distensibility more than 9.7% and PPV more than 12% predicted fluid responsiveness with a sensitivity of 100% and specificity of 95%.

Conclusion

IJV distensibility is an accurate, easily acquired non-invasive parameter of fluid responsiveness in mechanically ventilated septic patients with performance similar to PPV. The combined use of IJV distensibility with left-sided indexes of fluid responsiveness improves their predictive value.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0647-1) contains supplementary material, which is available to authorized users.     

Validation of the Better Care? system to detect ineffective efforts during expiration in mechanically ventilated patients: a pilot study

Purpose

Ineffective respiratory efforts during expiration (IEE) are a problem during mechanical ventilation (MV). The goal of this study is to validate mathematical algorithms that automatically detect IEE in a computerized (Better Care^?) system that obtains and processes data from intensive care unit (ICU) ventilators in real time.

Methods

The Better Care^? system, integrated with ICU health information systems, synchronizes and processes data from bedside technology. Algorithms were developed to analyze airflow waveforms during expiration to determine IEE. Data from 2,608,800 breaths from eight patients were recorded. From these breaths 1,024 were randomly selected. Five experts independently analyzed the selected breaths and classified them as IEE or not IEE. Better Care^? evaluated the same 1,024 breaths and assigned a score to each one. The IEE score cutoff point was determined based on the experts’ analysis. The IEE algorithm was subsequently validated using the electrical activity of the diaphragm (EAdi) signal to analyze 9,600 breaths in eight additional patients.

Results

Optimal sensitivity and specificity were achieved by setting the cutoff point for IEE by Better Care^? at 42%. A score?>42% was classified as an IEE with 91.5% sensitivity, 91.7% specificity, 80.3% positive predictive value (PPV), 96.7% negative predictive value (NPV), and 79.7% Kappa index [confidence interval (CI) (95%)?=?(75.6%; 83.8%)]. Compared with the EAdi, the IEE algorithm had 65.2% sensitivity, 99.3% specificity, 90.8% PPV, 96.5% NPV, and 73.9% Kappa index [CI (95%)?=?(71.3%; 76.3%)].

Conclusions

In this pilot, Better Care^? classified breaths as IEE in close agreement with experts and the EAdi signal.     

A comparative assessment of two conservative methods for the diagnosis of catheter-related infection in critically ill patients

Purpose

To assess the utility of two in situ techniques, differential time to positivity (DTP) and semiquantitative superficial cultures (SQSC) for diagnosing catheter-related bloodstream infection (CR-BSI) in critically ill adults.

Methods

This was a prospective cohort study in patients with suspected CR-BSI arising from a short-term arterial catheter (AC) or a central venous catheter (CVC). On suspicion of CR-BSI, devices were removed. Blood, skin, catheter tip and hub cultures were taken. Infection rates were compared against the diagnosis of CR-BSI using matched tip and blood cultures.

Results

Of 120 episodes of clinically suspected CR-BSI in 101 patients examined, 9 (7.5?%) were confirmed as CR-BSI. Validity values (95?% CI) for the diagnosis of CR-BSI arising from both AC and CVC for DTP were: sensitivity 44?% (15?C77?%), specificity 98?% (93?C100?%), positive predictive value (PPV) 67?% (24?C94?%), negative predictive value (NPV) 96?% (90?C98?%), positive likelihood ratio (LR+) 25 (5?C117), negative likelihood ratio (LR?) 0.6 (0.3?C1.0), diagnostic odds ratio (DOR) 44 (7?C258), and accuracy 94?% (92?C98?%). Validity values (95?% CI) for SQSC were: sensitivity 78?% (41?C96?%), specificity 60?% (50?C69?%), PPV 14?% (6?C26?%), NPV 97?% (89?C99?%), LR+ 1.9 (1.0?C2.3), LR? 0.4 (0.1?C1.3), DOR 5.1 (1.1?C19), and accuracy 61?% (51?C69?%). DTP combined with SQSC improved sensitivity and NPV to 100?% whilst the DOR increased to 25.8 (95?% CI 3?C454).

Conclusions

CR-BSI can be ruled out by undertaking DTP and SQSC concurrently for both ACs and CVCs with 100?% sensitivity and NPV.     

Fluid challenge: tracking changes in cardiac output with blood pressure monitoring (invasive or non-invasive)

Purpose

To assess whether invasive and non-invasive blood pressure (BP) monitoring allows the identification of patients who have responded to a fluid challenge, i.e., who have increased their cardiac output (CO).

Methods

Patients with signs of circulatory failure were prospectively included. Before and after a fluid challenge, CO and the mean of four intra-arterial and oscillometric brachial cuff BP measurements were collected. Fluid responsiveness was defined by an increase in CO ≥10 or ≥15 % in case of regular rhythm or arrhythmia, respectively.

Results

In 130 patients, the correlation between a fluid-induced increase in pulse pressure (Δ_500mlPP) and fluid-induced increase in CO was weak and was similar for invasive and non-invasive measurements of BP: r² = 0.31 and r² = 0.29, respectively (both p < 0.001). For the identification of responders, invasive Δ_500mlPP was associated with an area under the receiver-operating curve (AUC) of 0.82 (0.74–0.88), similar (p = 0.80) to that of non-invasive Δ_500mlPP [AUC of 0.81 (0.73–0.87)]. Outside large gray zones of inconclusive values (5–23 % for invasive Δ_500mlPP and 4–35 % for non-invasive Δ_500mlPP, involving 35 and 48 % of patients, respectively), the detection of responsiveness or unresponsiveness to fluid was reliable. Cardiac arrhythmia did not impair the performance of invasive or non-invasive Δ_500mlPP. Other BP-derived indices did not outperform Δ_500mlPP.

Conclusions

As evidenced by large gray zones, BP-derived indices poorly reflected fluid responsiveness. However, in our deeply sedated population, a high increase in invasive pulse pressure (>23 %) or even in non-invasive pulse pressure (>35 %) reliably detected a response to fluid. In the absence of a marked increase in pulse pressure (<4–5 %), a response to fluid was unlikely.     

Effect of pulse pressure on the predictability of stroke volume variation for fluid responsiveness in patients with coronary disease

Purpose

We hypothesized that the predictability of stroke volume variation (SVV) on fluid responsiveness would be reduced in patients with coronary disease who have wide pulse pressure (PP).

Methods

Sixty-six patients undergoing coronary surgery were divided into 2 groups according to the PP measured 1 day before surgery: normal PP (n = 33, PP ≤ 60 mm Hg) or wide PP (n = 33, PP > 60 mm Hg). After applying mechanical ventilation, hemodynamic parameters (including SVV measured by the FloTrac/Vigileo system [Edwards Lifesciences, Irvine, Calif]) were recorded before and 10 minutes after fluid replacement in a closed-chest condition. Prediction of fluid responsiveness was tested by calculating the area under the receiver operating characteristic curves.

Results

Twenty-one patients in the normal PP and 16 patients in the wide PP condition were fluid responders. The area under the receiver operating characteristic curves of SVV to predict fluid responsiveness were 0.808 (P = .022) and 0.609 (P = .288) in the normal PP and wide PP patients, respectively. In the normal PP condition, a SVV value of 13% discriminated between fluid responders and nonresponders with a sensitivity of 76% and a specificity of 67%.

Conclusions

In contrast to patients with normal PP, SVV does not predict fluid responsiveness in patients with coronary disease who have wide PP.     

Using color flow detection of air insufflation to improve accuracy in verifying nasogastric tube position

Objectives

Previous studies have shown that ultrasonography (USG), as an alternative to radiography, has a good accuracy in confirming nasogastric tube (NGT) position. Color flow detection of air insufflation is a novel approach in verifying NGT position. In our study, we aimed at evaluating its sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy in confirming the NGT position, as compared with 2-dimensional (2D) USG.

Clinical relevance of pulse pressure variations for predicting fluid responsiveness in mechanically ventilated intensive care unit patients: the grey zone approach

Introduction

Pulse pressure variation (PPV) has been shown to predict fluid responsiveness in ventilated intensive care unit (ICU) patients. The present study was aimed at assessing the diagnostic accuracy of PPV for prediction of fluid responsiveness by using the grey zone approach in a large population.

Methods

The study pooled data of 556 patients from nine French ICUs. Hemodynamic (PPV, central venous pressure (CVP) and cardiac output) and ventilator variables were recorded. Responders were defined as patients increasing their stroke volume more than or equal to 15% after fluid challenge. The receiver operating characteristic (ROC) curve and grey zone were defined for PPV. The grey zone was evaluated according to the risk of fluid infusion in hypoxemic patients.

Results

Fluid challenge led to increased stroke volume more than or equal to 15% in 267 patients (48%). The areas under the ROC curve of PPV and CVP were 0.73 (95% confidence interval (CI): 0.68 to 0.77) and 0.64 (95% CI 0.59 to 0.70), respectively (P <0.001). A grey zone of 4 to 17% (62% of patients) was found for PPV. A tidal volume more than or equal to 8 ml.kg⁻¹ and a driving pressure (plateau pressure - PEEP) more than 20 cmH₂O significantly improved the area under the ROC curve for PPV. When taking into account the risk of fluid infusion, the grey zone for PPV was 2 to 13%.

Conclusions

In ventilated ICU patients, PPV values between 4 and 17%, encountered in 62% patients exhibiting validity prerequisites, did not predict fluid responsiveness.     

Does pulse pressure variation predict fluid responsiveness in critically ill patients? A systematic review and meta-analysis

Introduction

Fluid resuscitation is crucial in managing hemodynamically unstable patients. The last decade witnessed the use of pulse pressure variation (PPV) to predict fluid responsiveness. However, as far as we know, no systematic review and meta-analysis has been carried out to evaluate the value of PPV in predicting fluid responsiveness specifically upon patients admitted into intensive care units.

Methods

We searched MEDLINE and EMBASE and included clinical trials that evaluated the association between PPV and fluid responsiveness after fluid challenge in mechanically ventilated patients in intensive care units. Data were synthesized using an exact binomial rendition of the bivariate mixed-effects regression model modified for synthesis of diagnostic test data.

Result

Twenty-two studies with 807 mechanically ventilated patients with tidal volume more than 8 ml/kg and without spontaneous breathing and cardiac arrhythmia were included, and 465 were responders (58%). The pooled sensitivity was 0.88 (95% confidence interval (CI) 0.81 to 0.92) and pooled specificity was 0.89 (95% CI 0.84 to 0.92). A summary receiver operating characteristic curve yielded an area under the curve of 0.94 (95% CI 0.91 to 0.95). A significant threshold effect was identified.

Conclusions

PPV predicts fluid responsiveness accurately in mechanically ventilated patients with relative large tidal volume and without spontaneous breathing and cardiac arrhythmia.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0650-6) contains supplementary material, which is available to authorized users.     

Differentiating malignant from benign thrombosis in hepatocellular carcinoma: contrast-enhanced ultrasound

Background

To determine the accuracy of contrast-enhanced ultrasonography (CEUS) in differentiating malignant and benign venous thrombosis complicating hepatocellular carcinoma (HCC).

Methods

Fifty patients (M:F = 41:9; age range 46–83 years) with HCC and venous thrombosis [portal vein (PV) in 45 and hepatic vein (HV) in 5] detected on CT or MR scan were evaluated with CEUS. Reference standard of malignant and benign thrombosis was based on serial clinicoradiologic follow-up (n = 43) or pathology (n = 7). Two independent, blinded readers retrospectively recorded the enhancement features of the venous thrombosis and diagnosed as benign or malignant thrombosis with a five-point confidence scale. Receiver operating characteristic (ROC) curves were calculated to determine the diagnostic performance of CEUS in differentiating malignant from benign thrombosis. Confidence level ratings were also used to calculate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for the diagnosis of malignant thrombosis. Inter-reader agreement was calculated using κ statistics in each assessed finding. Gray scale and Doppler characteristics of primary tumor and thrombosis were also assessed.

Results

Of the 50 patients, 37 were malignant (33 with PV thrombosis and 4 with HV thrombosis) and 13 were benign (12 with PV thrombosis and 1 with HV thrombosis). In ROC curve analysis for differentiating malignant from benign thrombosis, Az was 0.947 (CI 0.841–0.991) for reader 1 and 0.958 (CI 0.861–0.995) for reader 2 with excellent inter-reader agreement (κ = 0.86). When the confidence level ratings of 1 or 2 were considered malignant thrombosis, the sensitivity, specificity, PPV, and NPV in differentiating malignant from benign thrombosis were 100%, 83%, 95%, and 100% for reader 1 and 100%, 92%, 97%, and 100% for reader 2.

Conclusion

CEUS is useful to differentiate malignant and benign venous thrombosis associated with HCC with high diagnostic accuracy.