Validation of a new transpulmonary thermodilution system to assess global end-diastolic volume and extravascular lung water

Implementing AI Models for Prognostic Predictions in High-Risk Burn Patients

BACKGROUND AND OBJECTIVES

Burn injuries range from minor medical issues to severe, life-threatening conditions. The severity and location of the burn dictate its treatment; while minor burns might be treatable at home, severe burns necessitate medical intervention, sometimes in specialized burn centers with extended follow-up care. This study aims to leverage artificial intelligence (AI)/machine learning (ML) to forecast potential adverse effects in burn patients.

METHODS

This retrospective analysis considered burn patients admitted to Chi Mei Medical Center from 2010 to 2019. The study employed 14 features, comprising supplementary information like prior comorbidities and laboratory results, for building models for predicting graft surgery, a prolonged hospital stay, and overall adverse effects. Overall, 70% of the data set trained the AI models, with the remaining 30% reserved for testing. Three ML algorithms of random forest, LightGBM, and logistic regression were employed with evaluation metrics of accuracy, sensitivity, specificity, and the area under the receiver operating characteristic curve (AUC).

RESULTS

In this research, out of 224 patients assessed, the random forest model yielded the highest AUC for predictions related to prolonged hospital stays (>14 days) at 81.1%, followed by the XGBoost (79.9%) and LightGBM (79.5%) models. Besides, the random forest model of the need for a skin graft showed the highest AUC (78.8%), while the random forest model and XGBoost model of the occurrence of adverse complications both demonstrated the highest AUC (87.2%) as well. Based on the best models with the highest AUC values, an AI prediction system is designed and integrated into hospital information systems to assist physicians in the decision-making process.

CONCLUSIONS

AI techniques showcased exceptional capabilities for predicting a prolonged hospital stay, the need for a skin graft, and the occurrence of overall adverse complications for burn patients. The insights from our study fuel optimism for the inception of a novel predictive model that can seamlessly meld with hospital information systems, enhancing clinical decisions and bolstering physician-patient dialogues.

Transpulmonary thermodilution

PURPOSE OF REVIEW

The purpose of this article is to systematically review and critically assess the existing data regarding the use of transpulmonary thermodilution (TPTD), by providing a detailed description of technical aspects of TPTD techniques, appraising the use of TPTD-derived parameters in specific clinical settings, and exploring the limits of this technique.

RECENT FINDINGS

The aim of hemodynamic monitoring is to optimize cardiac output (CO) and therefore improve oxygen delivery to the tissues. Hemodynamic monitoring plays a fundamental role in the management of acutely ill patients. TPTD is a reliable, multiparametric, advanced cardiopulmonary monitoring technique providing not only hemodynamic parameters related to cardiac function, but also to the redistribution of the extravascular water in the thorax. The hemodynamic monitors available in the market usually couple the intermittent measurement of the CO by TPTD with the arterial pulse contour analysis, offering automatic calibration of continuous CO and an accurate assessment of cardiac preload and fluid responsiveness.

SUMMARY

The TPTD is an invasive but well tolerated, multiparametric, advanced cardiopulmonary monitoring technique, allowing a comprehensive assessment of cardiopulmonary condition. Beyond the CO estimation, TPTD provides several indices that help answering questions that clinicians ask themselves during hemodynamic management. TPTD-guided algorithm obtained by pulse contour analysis may be useful to optimize fluid resuscitation by titrating fluid therapy according to functional hemodynamic monitoring and to define safety criteria to avoid fluid overload by following the changes in the extravascular lung water (EVLW) and pulmonary vascular permeability index (PVPI).

Cardiac output monitoring with pulmonary versus trans-cardiopulmonary thermodilution in left ventricular assist devices: Interchangeable methods?

Cardiac output (CO) measurement is mandatory in patients with left ventricular assist devices (LVADs). Thermodilution with pulmonary artery catheter (PAC) remains the clinical gold standard to measure CO in these patients, however it is associated with several complications. Therefore, the agreement between PAC and new, minimally invasive monitoring methods in LVAD needs to be further investigated. The aim of this study was to assess the accuracy and reliability of transpulmonary thermodilution with a PiCCO2 monitor compared with pulmonary artery thermodilution with PAC in a LVAD. Continuous-flow LVADs were implanted in six mini-pigs to assist the left ventricle. We studied two methods of measuring CO—intermittent transpulmonary thermodilution (CO_TPTD) by PiCCO2 and intermittent pulmonary artery thermodilution by CAP, standard technique (CO_PTD)—obtained in four consecutive moments of the study: before starting the LVAD (basal moment), and with the LVAD started in normovolemia, hypervolemia (fluid overloading) and hypovolemia (shock hemorrhage). A total of 72 paired measurements were analysed. At the basal moment, CO_TPTD and CO_PTD were closely correlated (r² = 0.89), with a mean bias of −0.085 ± 0.245 L/min and percentage error of 16%. After 15 min of partial support LVAD, CO_TPTD and CO_PTD were closely correlated (r² = 0.79), with a mean bias of −0.040 ± 0.417 L/min and percentage error of 26%. After inducing hypervolemia, CO_TPTD and CO_PTD were closely correlated (r² = 0.78), with a mean bias of −0.093 ± 0.339 L/min and percentage error of 13%. After inducing hypovolemia, CO_TPTD and CO_PTD were closely correlated (r² = 0.76), with a mean bias of −0.045 ± 0.281 L/min and percentage error of 28%. This study demonstrates a good agreement between transpulmonary thermodilution by PiCCO monitor and pulmonary thermodilution by PAC in the intermittent measurement of CO in a porcine model with a continuous-flow LVAD.

Development and validation of a clinical prediction model of acute kidney injury in intensive care unit patients at a rural tertiary teaching hospital in South Africa: a study protocol

INTRODUCTION

Acute kidney injury (AKI) is a decline in renal function lasting hours to days. The rising global incidence of AKI, and associated costs of renal replacement therapy, is a public health priority. With the only therapeutic option being supportive therapy, prevention and early diagnosis will facilitate timely interventions to prevent progression to chronic kidney disease. While many factors have been identified as predictive of AKI, none have shown adequate sensitivity or specificity on their own. Many tools have been developed in developed-country cohorts with higher rates of non-communicable disease, and few have been validated and practically implemented. The development and validation of a predictive tool incorporating clinical, biochemical and imaging parameters, as well as quantification of their impact on the development of AKI, should make timely and improved prediction of AKI possible. This study is positioned to develop and validate an AKI prediction tool in critically ill patients at a rural tertiary hospital in South Africa.

METHOD AND ANALYSIS

Critically ill patients will be followed from admission until discharge or death. Risk factors for AKI will be identified and their impact quantified using statistical modelling. Internal validation of the developed model will be done on separate patients admitted at a different time. Furthermore, patients developing AKI will be monitored for 3 months to assess renal recovery and quality of life. The study will also explore the utility of endothelial monitoring using the biomarker Syndecan-1 and capillary leak measurements in predicting persistent AKI.

ETHICS AND DISSEMINATION

The study has been approved by the Walter Sisulu University Faculty of Health Science Research Ethics and Biosafety Committee (WSU No. 005/2021), and the Eastern Cape Department of Health Research Ethics (approval number: EC 202103006). The findings will be shared with facility management, and presented at relevant conferences and seminars.

Lung Ultrasound-Guided Fluid Management versus Standard Care in Surgical ICU Patients: A Randomised Controlled Trial

The value of lung ultrasound (LU) in assessing extravascular lung water (EVLW) was demonstrated by comparing LU with gold-standard methods for EVLW assessment. However, few studies have analysed the value of B-Line score (BLS) in guiding fluid management during critical illness. The purpose of this trial was to evaluate if a BLS-guided fluid management strategy could improve fluid balance and short-term mortality in surgical intensive care unit (ICU) patients. We conducted a randomised, controlled trial within the ICUs of two university hospitals. Critically ill patients were randomised upon ICU admission in a 1:1 ratio to BLS-guided fluid management (active group) or standard care (control group). In the active group, BLS was monitored daily until ICU discharge or day 28 (whichever came first). On the basis of BLS, different targets for daily fluid balance were set with the aim of avoiding or correcting moderate/severe EVLW increase. The primary outcome was 28-day mortality. Over 24 months, 166 ICU patients were enrolled in the trial and included in the final analysis. Trial results showed that daily BLS monitoring did not lead to a different cumulative fluid balance in surgical ICU patients as compared to standard care. Consecutively, no difference in 28-day mortality between groups was found (10.5% vs. 15.6%, p = 0.34). However, at least 400 patients would have been necessary for conclusive results.

New Advances in Monitoring Cardiac Output in Circulatory Mechanical Assistance Devices. A Validation Study in a Porcine Model

Cardiac output (CO) measurement by continuous pulmonary artery thermodilution (CO_CTD) has been studied in patients with pulsatile-flow LVADs (left ventricular assist devices), confirming the clinical utility. However, it has not been validated in patients with continuous-flow LVADs. Therefore, the aim of this study was to assess the validity of CO_CTD in continuous-flow LVADs. Continuous-flow LVADs were implanted in six miniature pigs for partial assistance of the left ventricle. Both methods of measuring CO—measurement by CO_CTD and intermittent pulmonary artery thermodilution, standard technique (CO_ITD)—were used in four consecutive moments of the study: before starting the LVAD (basal moment), and with the LVAD started in normovolemia, hypervolemia (fluid overloading), and hypovolemia (shock hemorrhage). At the basal moment, CO_CTD and CO_ITD were closely correlated (r² = 0.97), with a mean bias of −0.13 ± 0.16 L/min and percentage error of 11%. After 15 min of partial support LVAD, CO_CTD and CO_ITD were closely correlated (r² = 0.91), with a mean bias of 0.31 ± 0.35 L/min and percentage error of 20%. After inducing hypervolemia, CO_CTD and CO_ITD were closely correlated (r² = 0.99), with a mean bias of 0.04 ± 0.07 L/min and percentage error of 5%. After inducing hypovolemia, CO_CTD and CO_ITD were closely correlated (r² = 0.74), with a mean bias of 0.08 ± 0.22 L/min and percentage error of 19%. This study shows that continuous pulmonary thermodilution could be an alternative method of monitoring CO in a porcine model with a continuous-flow LVAD.

Comparison of global end-diastolic volume index derived from jugular and femoral indicator injection: a prospective observational study in patients equipped with both a PiCCO-2 and an EV-1000-device

Transpulmonary thermodilution (TPTD)-derived global end-diastolic volume index (GEDVI) is a static marker of preload which better predicted volume responsiveness compared to filling pressures in several studies. GEDVI can be generated with at least two devices: PiCCO and EV-1000. Several studies showed that uncorrected indicator injection into a femoral central venous catheter (CVC) results in a significant overestimation of GEDVI by the PiCCO-device. Therefore, the most recent PiCCO-algorithm corrects for femoral indicator injection. However, there are no systematic data on the impact of femoral indicator injection for the EV-1000 device. Furthermore, the correction algorithm of the PiCCO is poorly validated. Therefore, we prospectively analyzed 14 datasets from 10 patients with TPTD-monitoring undergoing central venous catheter (CVC)- and arterial line exchange. PiCCO was replaced by EV-1000, femoral CVCs were replaced by jugular/subclavian CVCs and vice-versa. For PiCCO, jugular and femoral indicator injection derived GEDVI was comparable when the correct information about femoral catheter site was given (p = 0.251). By contrast, GEDVI derived from femoral indicator injection using the EV-1000 was obviously not corrected and was substantially higher than jugular GEDVI measured by the EV-1000 (846 ± 250 vs. 712 ± 227 ml/m²; p = 0.001). Furthermore, measurements of GEDVI were not comparable between PiCCO and EV-1000 even in case of jugular indicator injection (p = 0.003). This is most probably due to different indexations of the raw value GEDV. EV-1000 could not be recommended to measure GEDVI in case of a femoral CVC. Furthermore, different indexations used by EV-1000 and PiCCO should be considered even in case of a jugular CVC when comparing GEDVI derived from PiCCO and EV-1000.

The inspiration hold maneuver is a reliable method to assess mean systemic filling pressure but its clinical value remains unclear

Background

The upstream pressure for venous return (VR) is considered to be a combined conceptual blood pressure of the systemic vessels: the mean systemic filling pressure (MSFP). The relevance of estimating the MSFP during dynamic changes of the circulation at the bedside is controversial. Herein, we studied the effect of high ventilatory pressures on the relationship between VR and central venous pressure (CVP).

Methods

In 9 healthy pigs under anaesthesia and mechanically ventilated, MSFP was estimated from extrapolated VR versus CVP relationships during inspiratory hold maneuvers (IHMs) with different levels of ventilatory pressure (Pvent). MSFP was measure 3 times per animal during euvolemia and hypovolemia. Hypovolemia was induced by bleeding with 10 mL/kg. The estimated MSFP values were compared to the blood pressure recording after induced ventricle fibrillation (i.e., mean circulatory filling pressure).

Results

Our results revealed a strong linear correlation between VR and CVP [R2 of 0.92 (range, 0.67–0.99)], during IHMs with different levels of Pvent. Volume status significantly alters the resulting MSFP, 20±1 and 16±2 mmHg for euvolemia and hypovolemia respectively. This estimation of the MSFP was strongly correlated—but not interchangeable—to the blood pressure recording after induced ventricle fibrillation (R2=0.8 and P=0.045).

Conclusions

In conclusion, we showed a strong linear correlation between VR and CVP—when applying IHMs with high levels of Pvent—however the clinical applicability of this method to guide volume therapy in its current form is improbable.

Noninvasive Monitoring in the Intensive Care Unit

There has been considerable development in the field of noninvasive hemodynamic monitoring in recent years. Multiple devices have been proposed to assess blood pressure, cardiac output, and tissue perfusion. All have their own advantages and disadvantages and selection should be based on individual patient requirements and disease severity and adjusted according to ongoing patient evolution.

What should I use next if clinical evaluation and echocardiographic haemodynamic assessment is not enough?

PURPOSE OF REVIEW

To provide an integrated clinical approach to the critically ill patients in shock.

RECENT FINDINGS

The complexity behind shock mechanism has improved in the last decades; as consequence, conventional generalized practices have been questioned, in favour of different approaches, titrated to patient's individual response. Bedside clinical examination has been demonstrated to be a reliable instrument to recognize the mismatch between cardiac function and peripheral oxygen demand. Mottling skin and capillary refill time have been recently proposed using a semi-quantitative approach as reliable tool to guide shock therapy; lactate, ΔCO2 and ScVO2 are also useful to track the effect of the therapies overtime. Critical care echocardiography is useful to assess the source of the shock, to choice the correct the therapy and to customize the therapy. Finally, a more sophisticated and invasive calibrated monitoring should be promptly adopted in case of refractory or mixed shock state to titrate the therapy on predefined goals, avoiding the inappropriate use of fluids and vasoactive drugs.

SUMMARY

Bedside haemodynamic assessment in critically ill patients should be considered an integrated approach supporting the decision-making process and should be based on clinical examination and critical care echocardiography.

Measurement of extravascular lung water to diagnose severe reperfusion lung injury following pulmonary endarterectomy: a prospective cohort clinical validation study

The measurement of extravascular lung water is a relatively new technology which has not yet been well validated as a clinically useful tool. We studied its utility in patients undergoing pulmonary endarterectomy as they frequently suffer reperfusion lung injury and associated oedematous lungs. Such patients are therefore ideal for evaluating this new monitor. We performed a prospective observational cohort study during which extravascular lung water index measurements were taken before and immediately after surgery and postoperatively in intensive care. Data were analysed for 57 patients; 21 patients (37%) experienced severe reperfusion lung injury. The first extravascular lung water index measurement after cardiopulmonary bypass failed to predict severe reperfusion lung injury, area under the receiver operating characteristic curve 0.59 (95%CI 0.44–0.74). On intensive care, extravascular lung water index correlated most strongly at 36 h, area under the receiver operating characteristic curve 0.90 (95%CI 0.80–1.00). Peri‐operative extravascular lung water index is not a useful measure to predict severe reperfusion lung injury after pulmonary endarterectomy, however, it does allow monitoring and measurement during the postoperative period. This study implies that extravascular lung water index can be used to directly assess pulmonary fluid overload and that monitoring patients by measuring extravascular lung water index during their intensive care stay is useful and correlates with their clinical course. This may allow directed, pre‐empted therapy to attenuate the effects and improve patient outcomes and should prompt further studies.

Correlation between urinary albumin to creatinine ratio and systemic glycocalyx degradation in pediatric sepsis

Background: Increased capillary permeability in sepsis is associated with several complications and worse outcomes. Glycocalyx degradation, marked by increased serum syndecan-1 levels, alters vascular permeability, which can manifest as albuminuria in the glomerulus. Therefore, elevated urinary albumin to creatinine ratio (ACR) potentially provides an index of systemic glycocalyx degradation. The aim of this study was to analyze the correlation between urinary ACR and serum syndecan-1 levels.Methods: A longitudinal prospective study with repeated cross-sectional design was conducted on children with sepsis in pediatric intensive care unit, we evaluated serum syndecan-1 levels and urinary ACR on days 1, 2, 3, and 7. A descriptive study on healthy children was also conducted to determine the reference value of syndecan-1 in children.Results: 49 subjects with sepsis were recruited. Based on the data of the healthy children group (n=30), syndecan-1 level of >90th percentile (41.42 ng/mL) was defined as systemic glycocalyx degradation. The correlation coefficients (r) between urinary ACR and syndecan-1 levels were 0.32 (p<0.001) from all examination days (162 specimens), 0.298 (p=0.038) on day 1, and 0.469 (p=0.002) on day 3. The area under the curve of urinary ACR and systemic glycocalyx degradation was 65.7% (95% CI 54.5%–77%; p=0.012). Urinary ACR ≥157.5 mg/g was determined as the cut-off point for glycocalyx degradation, with a sensitivity of 77.4% and a specificity of 48%.Conclusion: Urinary ACR showed a weak correlation with systemic glycocalyx degradation, indicating that the pathophysiology of elevated urinary ACR in sepsis is not merely related to glycocalyx degradation.

Extravascular lung water measurements in acute respiratory distress syndrome: why, how, and when?

PURPOSE OF REVIEW

Increase in pulmonary vascular permeability accompanied with accumulation of excess extravascular lung water (EVLW) is the hallmark of acute respiratory distress syndrome (ARDS). Currently, EVLW and pulmonary vascular permeability index (PVPI) can be quantitatively measured using the transpulmonary thermodilution (TPTD) technique. We will clarify why, how, and when EVLW and PVPI measurements should be performed.

RECENT FINDINGS

Although the Berlin criteria of ARDS are simple and widely used, several criticisms of them have been published. The last 2 decades have witnessed the introduction and evolution of the TPTD technique for measuring EVLW and PVPI. Several publications have recommended to evaluate EVLW and the PVPI during the treatment of critically ill patients. Accurate and objective diagnoses can be made for ARDS patients using EVLW and PVPI. EVLW more than 10 ml/kg is a reasonable criterion for pulmonary edema, and EVLW more than 15 ml/kg for a severe condition. In addition to EVLW more than 10 mL/kg, PVPI more than three suggests increased vascular permeability (i.e., ARDS), and PVPI less than 2 represent normal vascular permeability (i.e., cardiogenic pulmonary edema).

SUMMARY

EVLW and PVPI measurement will open the door to future ARDS clinical practice and research, and have potential to be included in the future ARDS definition.

A comparison of ventricular systolic function indices provided by VolumeView/EV1000™ and left ventricular ejection fraction by echocardiography among septic shock patients

The aim of this study was to compare the cardiac function index (CFI) and global ejection fraction (GEF) obtained by VolumeView/EV1000™, with the left ventricular ejection fraction (LVEF) by echocardiography in septic shock patients. A prospective observational study was conducted in a medical intensive care unit of a tertiary, teaching university hospital. Thirty-two, mechanical-ventilated septic shock patients were included in this study. We simultaneously measured CFI and GEF with LVEF. The correlation of CFI, GEF along with LVEF and ability of CFI and GEF to predict LVEF ≥ 40, 50 and 60% were evaluated. There were 192 pairs of CFI, GEF and LVEF. CFI was significantly correlated with GEF (r = 0.82, P < 0.0001). A significant correlation was observed between CFI and LVEF (r = 0.56, P < 0.0001) and GEF and LVEF (r = 0.71, P < 0.0001). The CFI and GEF had a good predictive ability for estimating LVEF ≥ 40, 50 and 60%, with an area under receiving operating characteristic (AUC) 0.875-0.934. The CFI ≥ 3/min predicted LVEF ≥ 40% with sensitivity 95.1% and specificity 48.3%. The GEF ≥ 15%, estimated LVEF ≥ 40% with sensitivity 92.6% and specificity 69%. There were 40 thermodilution and LVEF measurements obtained before and after norepinephrine adjustment. Blood pressure as well as the cardiac index were significantly increased, whereas there were no changes in CFI, GEF and LVEF values. Conclusions: Both CFI and GEF obtained by VolumeView/EV1000™, correlated with LVEF, so as to provide a reliable estimation of LV systolic function in septic shock patients.

Cardiac output measurement in liver transplantation patients using pulmonary and transpulmonary thermodilution: a comparative study

During liver transplantation surgery, the pulmonary artery catheter-despite its invasiveness-remains the gold standard for measuring cardiac output. However, the new EV1000 transpulmonary thermodilution calibration technique was recently introduced into the market by Edwards LifeSciences. We designed a single-center prospective observational study to determine if these two techniques for measuring cardiac output are interchangeable in this group of patients. Patients were monitored with both pulmonary artery catheter and the EV1000 system. Simultaneous intermittent cardiac output measurements were collected at predefined steps: after induction of anesthesia (T1), during the anhepatic phase (T2), after liver reperfusion (T3), and at the end of the surgery (T4). The 4-quadrant and polar plot techniques were used to assess trending ability between the two methods. We enrolled 49 patients who underwent orthotopic liver transplantation surgery. We analyzed a total of 588 paired measurements. The mean bias between pulmonary artery catheter and the EV1000 system was 0.35 L/min with 95% limits of agreement of - 2.30 to 3.01 L/min, and an overall percentage error of 35%. The concordance rate between the two techniques in 4-quadrant plot analysis was 65% overall. The concordance rate of the polar plot showed an overall value of 83% for all pairs. In the present study, in liver transplantation patients we found that intermittent cardiac output monitoring with EV1000 system showed a percentage error compared with pulmonary artery catheter in the acceptable threshold of 45%. On the others hand, our results showed a questionable trending ability between the two techniques.

Transpulmonary thermodilution: advantages and limits

Background

For complex patients in the intensive care unit or in the operating room, many questions regarding their haemodynamic management cannot be answered with simple clinical examination. In particular, arterial pressure allows only a rough estimation of cardiac output. Transpulmonary thermodilution is a technique that provides a full haemodynamic assessment through cardiac output and other indices.

Main body

Through the analysis of the thermodilution curve recorded at the tip of an arterial catheter after the injection of a cold bolus in the venous circulation, transpulmonary thermodilution intermittently measures cardiac output. This measure allows the calibration of pulse contour analysis. This provides continuous and real time monitoring of cardiac output, which is not possible with the pulmonary artery catheter. Transpulmonary thermodilution provides several variables beyond cardiac output. It estimates the end-diastolic volume of the four cardiac cavities, which is a marker of cardiac preload. It provides an estimation of the systolic function of the combined ventricles. It is more direct than the pulmonary artery catheter, but does not allow the distinct estimation of right and left cardiac function. It is easier and faster to perform than echocardiography, but does not provide a full evaluation of the cardiac structure and function. Transpulmonary thermodilution has the unique advantage of being able to estimate at the bedside extravascular lung water, which quantifies the volume of pulmonary oedema, and pulmonary vascular permeability, which quantifies the degree of a pulmonary capillary leak. Both indices are helpful for guiding fluid strategy, especially in case of acute respiratory distress syndrome.

Conclusions

Transpulmonary thermodilution provides a full cardiovascular evaluation that allows one to answer many questions regarding haemodynamic management. It belongs to the category of “advanced” devices that are indicated for the most critically ill and/or complex patients.

Femoral indicator injection for transpulmonary thermodilution using the EV1000/VolumeView(®): do the same criteria apply as for the PiCCO(®)?

OBJECTIVE

Comparison of global end-diastolic volume index (GEDVI) obtained by femoral and jugular transpulmonary thermodilution (TPTD) indicator injections using the EV1000/VolumnView(®) device (Edwards Lifesciences, Irvine, USA).

METHODS

In an 87-year-old woman with hypovolemic shock and equipped with both jugular and femoral vein access and monitored with the EV1000/VolumeView(®) device, we recorded 10 datasets, each comprising duplicate TPTD via femoral access and duplicate TPTD (20 ml cold saline) via jugular access.

RESULTS

Mean femoral GEDVI ((674.6±52.3) ml/m(2)) was significantly higher than jugular GEDVI ((552.3±69.7) ml/m(2)), with P=0.003. Bland-Altman analysis demonstrated a bias of (+122±61) ml/m(2), limits of agreement of -16 and +260 ml/m(2), and a percentage error of 22%. Use of the correction-formula recently suggested for the PiCCO(®) device significantly reduced bias and percentage error. Similarly, mean values of parameters derived from GEDVI such as pulmonary vascular permeability index (PVPI; 1.244±0.101 vs. 1.522±0.139; P<0.001) and global ejection fraction (GEF; (24.7±1.6)% vs. (28.1±1.8)%; P<0.001) were significantly different in the case of femoral compared to jugular indicator injection. Furthermore, the mean cardiac index derived from femoral indicator injection ((4.50±0.36) L/(min·m²)) was significantly higher (P=0.02) than that derived from jugular indicator injection ((4.12±0.44) L/(min·m²)), resulting in a bias of (+0.38±0.37) L/(min·m²) and a percentage error of 19.4%.

CONCLUSIONS

Femoral access for indicator injection results in markedly altered values provided by the EV1000/VolumeView(®), particularly for GEDVI, PVPI, and GEF.

Global end-diastolic volume an emerging preload marker vis-a-vis other markers - Have we reached our goal?

A reliable estimation of cardiac preload is helpful in the management of severe circulatory dysfunction. The estimation of cardiac preload has evolved from nuclear angiography, pulmonary artery catheterization to echocardiography, and transpulmonary thermodilution (TPTD). Global end-diastolic volume (GEDV) is the combined end-diastolic volumes of all the four cardiac chambers. GEDV has been demonstrated to be a reliable preload marker in comparison with traditionally used pulmonary artery catheter-derived pressure preload parameters. Recently, a new TPTD system called EV1000™ has been developed and introduced into the expanding field of advanced hemodynamic monitoring. GEDV has emerged as a better preload marker than its previous conventional counterparts. The advantage of it being measured by minimum invasive methods such as PiCCO™ and newly developed EV1000™ system makes it a promising bedside advanced hemodynamic parameter.

Impact of misplaced subclavian vein catheter into jugular vein on transpulmonary thermodilution measurement variables

OBJECTIVE

The subclavian vein (SCV) is usually used to inject the indicator of cold saline for a transpulmonary thermodilution (TPTD) measurement. The SCV catheter being misplaced into the internal jugular (IJV) vein is a common occurrence. The present study explores the influence of a misplaced SCV catheter on TPTD variables.

METHODS

Thirteen severe acute pancreatitis (SAP) patients with malposition of the SCV catheter were enrolled in this study. TPTD variables including cardiac index (CI), global end-diastolic volume index (GEDVI), intrathoracic blood volume index (ITBVI), and extravascular lung water index (EVLWI) were obtained after injection of cold saline via the misplaced SCV catheter. Then, the misplaced SCV catheter was removed and IJV access was constructed for a further set of TPTD variables. Comparisons were made between the TPTD results measured through the IJV and misplaced SCV accesses.

RESULTS

A total of 104 measurements were made from TPTD curves after injection of cold saline via the IJV and misplaced SCV accesses. Bland-Altman analysis demonstrated an overestimation of +111.40 ml/m(2) (limits of agreement: 6.13 and 216.70 ml/m(2)) for GEDVI and ITBVI after a misplaced SCV injection. There were no significant influences on CI and EVLWI. The biases of +0.17 L/(min·m(2)) for CI and +0.17 ml/kg for EVLWI were revealed by Bland-Altman analysis.

CONCLUSIONS

The malposition of an SCV catheter does influence the accuracy of TPTD variables, especially GEDVI and ITBVI. The position of the SCV catheter should be confirmed by chest X-ray in order to make good use of the TPTD measurements.

Advanced Hemodynamic Management in Patients with Septic Shock

In patients with sepsis and septic shock, the hemodynamic management in both early and later phases of these "organ dysfunction syndromes" is a key therapeutic component. It needs, however, to be differentiated between "early goal-directed therapy" (EGDT) as proposed for the first 6 hours of emergency department treatment by Rivers et al. in 2001 and "hemodynamic management" using advanced hemodynamic monitoring in the intensive care unit (ICU). Recent large trials demonstrated that nowadays protocolized EGDT does not seem to be superior to "usual care" in terms of a reduction in mortality in emergency department patients with early identified septic shock who promptly receive antibiotic therapy and fluid resuscitation. "Hemodynamic management" comprises (a) making the diagnosis of septic shock as one differential diagnosis of circulatory shock, (b) assessing the hemodynamic status including the identification of therapeutic conflicts, and (c) guiding therapeutic interventions. We propose two algorithms for hemodynamic management using transpulmonary thermodilution-derived variables aiming to optimize the cardiocirculatory and pulmonary status in adult ICU patients with septic shock. The complexity and heterogeneity of patients with septic shock implies that individualized approaches for hemodynamic management are mandatory. Defining individual hemodynamic target values for patients with septic shock in different phases of the disease must be the focus of future studies.

Pulse waveform hemodynamic monitoring devices: recent advances and the place in goal-directed therapy in cardiac surgical patients

Hemodynamic monitoring has evolved and improved greatly during the past decades as the medical approach has shifted from a static to a functional approach. The technological advances have led to innovating calibrated or not, but minimally invasive and noninvasive devices based on arterial pressure waveform (APW) analysis. This systematic clinical review outlines the physiologic rationale behind these recent technologies. We describe the strengths and the limitations of each method in terms of accuracy and precision of measuring the flow parameters (stroke volume, cardiac output) and dynamic parameters which predict the fluid responsiveness. We also analyzed the place of the APW monitoring devices in goal-directed therapy (GDT) protocols in cardiac surgical patients. According to the data from the three GDT-randomized control trials performed in cardiac surgery (using two types of APW techniques PiCCO and FloTrac/Vigileo), these devices did not demonstrate that they played a role in decreasing mortality, but only decreasing the ventilation time and the ICU and hospital length of stay.

Perioperative fluid volume optimization following proximal femoral fracture

BACKGROUND

Proximal femoral fracture (PFF) is a common orthopaedic emergency that affects mainly elderly people at high risk of complications. Advanced methods for managing fluid therapy during treatment for PFF are available, but their role in reducing risk is unclear.

OBJECTIVES

To compare the safety and effectiveness of the following methods of perioperative fluid optimization in adult participants undergoing surgical repair of hip fracture: advanced invasive haemodynamic monitoring, such as transoesophageal Doppler and pulse contour analysis; a protocol using standard measures, such as blood pressure, urine output and central venous pressure; and usual care.Comparisons of fluid types (e.g. crystalloid vs colloid) and other methods of optimizing oxygen delivery, such as blood product therapies and pharmacological treatment with inotropes and vasoactive drugs, are considered in other reviews.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 9); MEDLINE (October 2012 to September 2015); and EMBASE (October 2012 to September 2015) without language restrictions. We ran forward and backward citation searches on identified trials. We searched ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform for unpublished trials. This is an updated version of a review published originally in 2004 and updated first in 2013 and again in 2015. Original searches were performed in October 2003 and October 2012.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in adult participants undergoing surgical treatment for PFF that compared any two of advanced haemodynamic monitoring, protocols using standard measures or usual care, irrespective of blinding, language or publication status.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the impact of fluid optimization interventions on outcomes of mortality, length of hospital stay, time to medical fitness, whether participants were able to return to pre-fracture accommodation at six months, participant mobility at six months and adverse events in-hospital. We pooled data using risk ratio (RR) or mean difference (MD) for dichotomous or continuous data, respectively, on the basis of random-effects models.

MAIN RESULTS

We included in this updated review five RCTs with a total of 403 participants, and we added two new trials identified during the 2015 search. One of the included studies was found to have a high risk of bias; no trial featured all pre-specified outcomes. We found two trials for which data are awaited for classification and one ongoing trial.Three studies compared advanced haemodynamic monitoring with a protocol using standard measures; three compared advanced haemodynamic monitoring with usual care; and one compared a protocol using standard measures with usual care. Meta-analyses for the two advanced haemodynamic monitoring comparisons are consistent with both increased and decreased risk of mortality (RR Mantel-Haenszel (M-H) random-effects 0.41, 95% confidence interval (CI) 0.14 to 1.20; 280 participants; RR M-H random-effects 0.45, 95% CI 0.07 to 2.95; 213 participants, respectively). The study comparing a protocol with usual care found no difference between groups for this outcome.Three studies comparing advanced haemodynamic monitoring with usual care reported data for length of stay and time to medical fitness. There was no statistically significant difference between groups for these outcomes in the two studies that we were able to combine (MD IV fixed 0.63, 95% CI -1.70 to 2.96); MD IV fixed 0.01, 95% CI -1.74 to 1.71, respectively) and no statistically significant difference in the third study. One study reported reduced time to medical fitness when comparing advanced haemodynamic monitoring with a protocol, and when comparing protocol monitoring with usual care.The number of participants with one or more complications showed no statistically significant differences in each of the two advanced haemodynamic monitoring comparisons (RR M-H random-effects 0.83, 95% CI 0.59 to 1.17; 280 participants; RR M-H random-effects 0.72, 95% CI 0.40 to 1.31; 173 participants, respectively), nor any differences in the protocol and usual care comparison.Only one study reported the number of participants able to return to normal accommodation after discharge with no statistically significant difference between groups.There were few studies with a small number of participants, and by using the GRADE (Grades of Recommendation, Assessment, Development and Evaluation Working Group) approach, we judged the quality of the outcome evidence as low. We had included one study with a high risk of bias, but upon applying GRADE, we downgraded the quality of this outcome evidence to very low.

AUTHORS' CONCLUSIONS

Five studies including a total of 403 participants provided no evidence that fluid optimization strategies improve outcomes for participants undergoing surgery for PFF. Further research powered to test some of these outcomes is ongoing.

Reproducibility of transpulmonary thermodilution cardiac output measurements in clinical practice: a systematic review

Measuring cardiac output (CO) is an integral part of the diagnostic and therapeutic strategy in critically ill patients. During the last decade, the single transpulmonary thermodilution (TPTD) technique was implemented in clinical practice. The purpose of this paper was to systematically review and critically assess the existing data concerning the reproducibility of CO measured using TPTD (COTPTD). A total of 16 studies were identified to potentially be included in our study because these studies had the required information that allowed for calculating the reproducibility of COTPTD measurements. 14 adult studies and 2 pediatric studies were analyzed. In total, 3432 averaged CO values in the adult population and 78 averaged CO values in the pediatric population were analyzed. The overall reproducibility of COTPTD measurements was 6.1 ± 2.0 % in the adult studies and 3.9 ± 2.9 % in the pediatric studies. An average of 3 boluses was necessary for obtaining a mean CO value. Achieving more than 3 boluses did not improve reproducibility; however, achieving less than 3 boluses significantly affects the reproducibility of this technique. The present results emphasize that TPTD is a highly reproducible technique for monitoring CO in critically ill patients, especially in the pediatric population. Our findings suggest that obtaining a mean of 3 measurements for determining CO values is recommended.

Extravascular lung water in critical care: recent advances and clinical applications

Extravascular lung water (EVLW) is the amount of fluid that is accumulated in the interstitial and alveolar spaces. In lung oedema, EVLW increases either because of increased lung permeability or because of increased hydrostatic pressure in the pulmonary capillaries, or both. Increased EVLW is always potentially life-threatening, mainly because it impairs gas exchange and reduces lung compliance. The only technique that provides an easy measurement of EVLW at the bedside is transpulmonary thermodilution. The validation of EVLW measurements by thermodilution was based on studies showing reasonable correlations with gravimetry or thermo-dye dilution in experimental and clinical studies. EVLW should be indexed to predicted body weight. This indexation reduces the proportion of ARDS patients for whom EVLW is in the normal range. Compared to non-indexed EVLW, indexed EVLW (EVLWI) is better correlated with the lung injury score and the oxygenation and it is a better predictor of mortality of patients with acute lung injury or acute respiratory distress syndrome (ARDS). Transpulmonary thermodilution also provides the pulmonary vascular permeability index (PVPI), which is an indirect reflection of the integrity of the alveolocapillary barrier. As clinical applications, EVLWI and PVPI may be useful to guide fluid management of patients at risk of fluid overload, as during septic shock and ARDS. High EVLWI and PVPI values predict mortality in several categories of critically ill patients, especially during ARDS. Thus, fluid administration should be limited when EVLWI is already high. Whatever the value of EVLWI, PVPI may indicate that fluid administration is particularly at risk of aggravating lung oedema. In the acute phase of haemodynamic resuscitation during septic shock and ARDS, high EVLWI and PVPI values may warn of the risk of fluid overload and prevent excessive volume expansion. At the post-resuscitation phase, they may prompt initiation of fluid removal thereby achieving a negative fluid balance.

Influence of early goal-directed therapy using arterial waveform analysis on major complications after high-risk abdominal surgery: study protocol for a multicenter randomized controlled superiority trial

Background

Early goal-directed therapy refers to the use of predefined hemodynamic goals to optimize tissue oxygen delivery in critically ill patients. Its application in high-risk abdominal surgery is, however, hindered by safety concerns and practical limitations of perioperative hemodynamic monitoring. Arterial waveform analysis provides an easy, minimally invasive alternative to conventional monitoring techniques, and could be valuable in early goal-directed strategies. We therefore investigate the effects of early goal-directed therapy using arterial waveform analysis on complications, quality of life and healthcare costs after high-risk abdominal surgery.

Methods/Design

In this multicenter, randomized, controlled superiority trial, 542 patients scheduled for elective, high-risk abdominal surgery will be included. Patients are allocated to standard care (control group) or early goal-directed therapy (intervention group) using a randomization procedure stratified by center and type of surgery. In the control group, standard perioperative hemodynamic monitoring is applied. In the intervention group, early goal-directed therapy is added to standard care, based on continuous monitoring of cardiac output with arterial waveform analysis. A treatment algorithm is used as guidance for fluid and inotropic therapy to maintain cardiac output above a preset, age-dependent target value. The primary outcome measure is a combined endpoint of major complications in the first 30 days after the operation, including mortality. Secondary endpoints are length of stay in the hospital, length of stay in the intensive care or post-anesthesia care unit, the number of minor complications, quality of life, cost-effectiveness and one-year mortality and morbidity.

Discussion

Before the start of the study, hemodynamic optimization by early goal-directed therapy with arterial waveform analysis had only been investigated in small, single-center studies, including minor complications as primary endpoint. Moreover, these studies did not include quality of life, healthcare costs, and long-term outcome in their analysis. As a result, the definitive role of arterial waveform analysis in the perioperative hemodynamic assessment and care for high-risk surgical patients is unknown, which gave rise to the present trial. Patient inclusion started in May 2012 and is expected to end in 2016.

Trial registration

This trial was registered in the Dutch Trial Register (registration number NTR3380) on 3 April 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/1745-6215-15-360) contains supplementary material, which is available to authorized users.

Room-temperature vs iced saline indicator injection for transpulmonary thermodilution

PURPOSE

Ice-cold injectate is assumed to provide best accuracy for transpulmonary thermodilution (TPTD)-derived cardiac index (CI), global end-diastolic volume index (GEDVI), and extravascular lung-water index (EVLWI). Room-temperature injectate might facilitate TPTD. Therefore, this study compares TPTD-results derived from iced injectate with room-temperature injectate TPTDs (TPTDRoom).

MATERIALS AND METHODS

Forty-five adult intensive care unit patients with PiCCO monitoring (Pulsion Medical Systems, Munich, Germany) were included in this observational study. Four hundred one sets of TPTDs were recorded. Each set consisted of four 15 mL TPTDs (twice with 21°C and subsequently twice with 4°C saline). Means of 2 TPTDRoom were compared with means of 2 cold TPTDs (primary end point).

RESULTS

Mean CI (4.70±1.60 vs 4.54±1.52 L/min per square meter; P<.001), GEDVI (985±294 vs 954±269 mL/m2; P<.001), and EVLWI (14.4±7.8 vs 13.8±7.3 mL/kg; P<.001) were significantly higher for TPTDRoom compared with TPTD-results derived from iced injectate. Mean bias and percentage error were 0.15±0.52 L/min per square meter and 21.9% for CI, 30±145 mL/m2 and 29.3% for GEDVI, and 0.59±2.1 mL/kg and 29.3% for EVLWI. Percentage error values were higher in case of femoral compared with jugular indicator injection for CI (25% vs 20%), GEDVI (35% vs 25%), and EVLWI (41% vs 23%).

CONCLUSIONS

Room-temperature injectate TPTDs results in slight but significant overestimation of CI, GEDVI, and EVLWI. Percentage error values for GEDVIRoom and EVLWIRoom are acceptable only in case of "jugular" indicator injection.

The role of invasive techniques in cardiopulmonary evaluation

PURPOSE OF REVIEW

To discuss the role of the invasive monitoring techniques pulmonary artery catheter (PAC) and transpulmonary thermodilution (TPD) for cardiopulmonary monitoring in the critically ill patient.

RECENT FINDINGS

Characterization of the nature of hemodynamic alterations and hemodynamic optimization can be achieved both with PAC and TPD. Some recent trials suggest that volumetric measurements may be preferred in conditions with preserved left ventricular systolic function, whereas pressure measurements should be preferred in patients with altered left ventricular systolic function. Extravascular lung water is strongly associated with outcome and may be used to reflect the impact of fluid management strategies. The time response of this measurement needs still to be better defined.

SUMMARY

This review highlights that PAC and TPD have an important role in cardiopulmonary monitoring of critically ill patients. Both techniques can be used efficiently to diagnose the nature of circulatory or respiratory failure and to monitor the effects of therapies. The choice of the technique should be guided by the patient's condition and the need for additional measurements rather than based on physician's preferences.

Perioperative fluid volume optimization following proximal femoral fracture

BACKGROUND

Proximal femoral fracture (PFF) is a common orthopaedic emergency, affecting mainly elderly people at high risk of complications. Advanced methods for managing fluid therapy during treatment for PFF are available, but their role in reducing risk is unclear.

OBJECTIVES

To compare the safety and effectiveness of different methods of perioperative fluid optimization in adult participants undergoing surgical repair of hip fracture. We considered the following methods: advanced invasive haemodynamic monitoring, such as transoesophageal Doppler and pulse contour analysis; a protocol using standard measures, such as blood pressure, urine output and central venous pressure; and usual care.Comparisons of fluid types (e.g. crystalloid vs colloid) and other methods of optimizing oxygen delivery, such as blood product therapies and pharmacological treatment with inotropes and vasoactive drugs, are considered elsewhere.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 9); MEDLINE (1966 to October 2012); and EMBASE (1980 to October 2012) without language restrictions. We ran forward and backward citation searches on identified trials. We contacted authors and searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform for unpublished trials. This is an updated version of a review published in 2004. The original search was performed in October 2003.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) in adult participants undergoing surgical treatment for PFF, which compared any two of advanced haemodynamic monitoring, protocols using standard measures or usual care, irrespective of blinding, language or publication status.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the impact of fluid optimization interventions on outcomes of mortality, length of hospital stay, return of participant to pre-fracture accommodation and mobility at six months and adverse events in hospital. We pooled data using risk ratio or mean difference for dichotomous or continuous data, respectively, based on random-effects models.

MAIN RESULTS

We included three RCTs with a total of 200 participants. One of these included studies was found to have a high risk of bias; no trial featured all pre-specified outcomes. We found one trial for which data are awaited for classification and two ongoing trials. One included study with low risk of bias found that compared with usual care, time to medical fitness for discharge was shorter with the use of advanced haemodynamic monitoring (mean reduction 6.20 days, 95% CI 2.3 to 10.1 days; 59 participants, one trial) and with the use of protocols that apply standard measures (mean reduction 3.9 days, 95% CI 0.75 to 7.05; 57 participants, one trial). Our results are consistent with both increased and decreased risk of mortality and adverse events in participants receiving the intervention. No data for other outcomes were available. Our results are limited by the quantity of available data.

AUTHORS' CONCLUSIONS

Three studies considering a total of 200 participants reveal an absence of evidence that fluid optimization strategies improve outcomes for participants undergoing surgery for PFF. Length of hospital stay may be improved, but lack of good quality data leaves uncertainty. Further research powered to test some of these outcomes is ongoing.

Monitoring cardiac function: echocardiography, pulse contour analysis and beyond

Haemodynamic monitoring has developed considerably over the last decades, nowadays comprising a wide spectrum of different technologies ranging from invasive to completely non-invasive techniques. At present, the evidence to continuously measure and optimise stroke volume, that is, cardiac output, in order to prevent occult hypoperfusion in the perioperative setting and consequently to improve patients' outcome is substantial. Surprisingly, there is a striking discrepancy between the developments in advanced haemodynamic monitoring combined with evidence-based knowledge on the one hand and daily clinical routine on the other hand. Recent trials have shown that perioperative mortality is higher than anticipated, emphasising the need for the speciality of anaesthesiology to face the problem and to translate proven concepts into clinical routine to improve patients' outcome. One basic principle of these concepts is to monitor and to optimise cardiac function by means of advanced haemodynamic monitoring, using echocardiography, pulse contour analysis and beyond.

The role for invasive monitoring in acute lung injury

Because acute lung injury (ALI) may arise from diverse and heterogeneous clinical insults, monitoring strategies for patients with ALI are heterogeneous as well. This review divides the monitoring strategies for ALI into three distinct phases. The "at-risk phase" is the period in which patients are at risk for ALI, and interventions may be applied to minimize or eliminate this risk. The "ALI phase" is the period during which ALI has occurred and requires attentive clinical management. The "resolution phase" is the period defined by resolution of ALI and successful discontinuation of mechanical ventilation. These phases are arbitrary, but they provide a useful framework for discussing the temporal changes in patient condition and monitoring goals in ALI.Invasive hemodynamic monitoring has specific roles in each phase of therapy for patients with ALI: pre-ALI, peri-ALI, and post-ALI. The primary goals are to optimize fluid resuscitation to prevent organ dysfunction, including ALI, and if ALI occurs to additional optimize fluid balance vis-à-vis the lung. By judicious application of invasive hemodynamic monitoring, particularly in its more modern iterations, clinicians can optimize the ebb and flow phases common to critically ill patients. This is vitally important given our current and growing understanding of the relationship between fluid balance and important clinical outcomes, multiple organ dysfunction syndrome, and mortality.

Performance of a new pulse contour method for continuous cardiac output monitoring: validation in critically ill patients

BACKGROUND

A new calibrated pulse wave analysis method (VolumeView™/EV1000™, Edwards Lifesciences, Irvine, CA, USA) has been developed to continuously monitor cardiac output (CO). The aim of this study was to compare the performance of the VolumeView method, and of the PiCCO2™ pulse contour method (Pulsion Medical Systems, Munich, Germany), with reference transpulmonary thermodilution (TPTD) CO measurements.

METHODS

This was a prospective, multicentre observational study performed in the surgical and interdisciplinary intensive care units of four tertiary hospitals. Seventy-two critically ill patients were monitored with a central venous catheter, and a thermistor-tipped femoral arterial VolumeView™ catheter connected to the EV1000™ monitor. After initial calibration by TPTD CO was continuously assessed using the VolumeView-CCO software (CCO(VolumeView)) during a 72 h period. TPTD was performed in order to obtain reference CO values (COREF). TPTD and arterial wave signals were transmitted to a PiCCO2™ monitor in order to obtain CCO(PiCCO) values. CCO(VolumeView) and CCO(PiCCO) were recorded over a 5 min interval before assessment of CO(TPTD). Bland-Altman analysis, %(errors), and concordance (trend analysis) were calculated.

RESULTS

A total of 338 matched sets of data were available for comparison. Bias for CCO(VolumeView)-CO(REF) was -0.07 litre min(-1) and for CCO(PiCCO)-CO(REF) +0.03 litre min(-1). Corresponding limits of agreement were 2.00 and 2.48 litre min(-1) (P<0.01), %(errors) 29 and 37%, respectively. Trending capabilities were comparable for both techniques.

CONCLUSIONS

The performance of the new VolumeView™-CCO method is as reliable as the PiCCO2™-CCO pulse wave analysis in critically ill patients. However, an improved precision was observed with the VolumeView™ technique. CLINICALTRIALS.GOV IDENTIFIER: NCT01405040.

Clinical review: Does it matter which hemodynamic monitoring system is used?

Hemodynamic monitoring and management has greatly improved during the past decade. Technologies have evolved from very invasive to non-invasive, and the philosophy has shifted from a static approach to a functional approach. However, despite these major changes, the critical care community still has potential to improve its ability to adopt the most modern standards of research methodology in order to more effectively evaluate new monitoring systems and their impact on patient outcome. Today, despite the huge enthusiasm raised by new hemodynamic monitoring systems, there is still a big gap between clinical research studies evaluating these monitors and clinical practice. A few studies, especially in the perioperative period, have shown that hemodynamic monitoring systems coupled with treatment protocols can improve patient outcome. These trials are small and, overall, the corpus of science related to this topic does not yet fit the standard of clinical research methodology encountered in other specialties such as cardiology and oncology. Larger randomized trials or quality improvement processes will probably answer questions related to the real impact of these systems.

Less-invasive approaches to perioperative haemodynamic optimization

PURPOSE OF REVIEW

A number of less-invasive haemodynamic monitoring devices have been introduced in recent years, largely replacing the pulmonary artery catheter (PAC) as a standard monitoring tool. Apart from tracking cardiac output (CO), these monitors provide additional haemodynamic parameters. The aim of this article is to review the most widely used less-invasive monitoring modalities, their technical characteristics and limitations regarding their clinical performance.

RECENT FINDINGS

The utilization of CO monitoring in the perioperative setting has been shown to be associated with improved outcomes if integrated into a haemodynamic optimization strategy. These findings provide the basis of recent recommendations for perioperative monitoring.

SUMMARY

An array of monitoring modalities have been introduced that can reliably track CO in the perioperative setting and make the PAC dispensable in most clinical situations. In order to be used safely and efficiently, knowledge regarding the inherent monitoring techniques and their limitations, their clinical validity and the utility of the parameters provided is crucial.

Prediction of fluid responsiveness in patients admitted to the medical intensive care unit

PURPOSE

Accurate prediction of fluid responsiveness is of importance in the treatment of patients admitted to the intensive care unit (ICU). We investigated whether physical examination, central venous pressure (CVP), central venous oxygen saturation (ScvO2), passive leg raising (PLR) test, and transpulmonary thermodilution (TPTD)-derived parameters can predict volume responsiveness in patients admitted to the ICU.

MATERIALS AND METHODS

In this prospective study, structured clinical examination, measurement of CVP and ScvO2, a PLR test, and TPTD measurements were performed in 31 patients. A fluid challenge test was performed in 24 patients (fluid responsiveness was defined as a cardiac index [CI] increase of ≥ 15%).

RESULTS

Physical examination, CVP, ScvO2, the PLR test, and the TPTD-derived volumetric preload parameter global end-diastolic volume index showed poor prognostic capabilities regarding prediction of fluid responsiveness. Twenty-nine percent of patients were fluid responsive. There was a statistically significant correlation between the fluid challenge-induced increase in CI and changes in global end-diastolic volume index (r = 0.666, P < .001). In only 17% of patients, CI did not increase after fluid loading.

CONCLUSIONS

Prediction of fluid responsiveness is difficult using physical examination, CVP, ScvO2, PLR maneuver, or TPTD-derived variables in critically ill patients. A volume challenge test should be considered for the assessment of fluid responsiveness in critically ill patients admitted to the ICU.

Clinical validation of a new thermodilution system for the assessment of cardiac output and volumetric parameters

INTRODUCTION

Transpulmonary thermodilution is used to measure cardiac output (CO), global end-diastolic volume (GEDV) and extravascular lung water (EVLW). A system has been introduced (VolumeView/EV1000™ system, Edwards Lifesciences, Irvine CA, USA) that employs a novel algorithm for the mathematical analysis of the thermodilution curve. Our aim was to evaluate the agreement of this method with the established PiCCO™ method (Pulsion Medical Systems SE, Munich, Germany, clinicaltrials.gov identifier: NCT01405040) METHODS: Seventy-two critically ill patients with clinical indication for advanced hemodynamic monitoring were included in this prospective, multicenter, observational study. During a 72-hour observation period, 443 sets of thermodilution measurements were performed with the new system. These measurements were electronically recorded, converted into an analog resistance signal and then re-analyzed by a PiCCO2™ device (Pulsion Medical Systems SE).

RESULTS

For CO, GEDV, and EVLW, the systems showed a high correlation (r(2) = 0.981, 0.926 and 0.971, respectively), minimal bias (0.2 L/minute, 29.4 ml and 36.8 ml), and a low percentage error (9.7%, 11.5% and 12.2%). Changes in CO, GEDV and EVLW were tracked with a high concordance between the two systems, with a traditional concordance for CO, GEDV, and EVLW of 98.5%, 95.1%, and 97.7% and a polar plot concordance of 100%, 99.8% and 99.8% for CO, GEDV, and EVLW, respectively. Radial limits of agreement for CO, GEDV and EVLW were 0.31 ml/minute, 81 ml and 40 ml, respectively. The precision of GEDV measurements was significantly better using the VolumeView™ algorithm compared to the PiCCO™ algorithm (0.033 (0.03) versus 0.040 (0.03; median (interquartile range), P = 0.000049).

CONCLUSIONS

For CO, GEDV, and EVLW, the agreement of both the individual measurements as well as measurements of change showed the interchangeability of the two methods. For the VolumeView method, the higher precision may indicate a more robust GEDV algorithm.

TRIAL REGISTRATION

clinicaltrials.gov NCT01405040.

Arterial waveform analysis in anesthesia and critical care

PURPOSE OF REVIEW

In this review, we describe the basic principles of arterial waveform analysis (AWA) to assess cardiac output (CO) and cardiac preload. The validity of commercially based hemodynamic monitoring systems is discussed, together with their clinical applications and limitations.

RECENT FINDINGS

Currently, three devices (the FloTrac system, PiCCO monitor, and LiDCO system) are available for measurement of AWA-based CO. In addition, dynamic preload parameters such as stroke volume variation (SVV) and pulse pressure variation (PPV) are determined, which may be useful to predict fluid responsiveness in mechanically ventilated patients.

SUMMARY

AWA provides a less invasive and easy-to-use alternative for CO measurement. The validity of AWA devices has been verified in a variety of patients and circumstances, but their performance is compromised in the presence of hemodynamic instability, cardiac arrhythmias, or other factors disturbing the arterial pressure waveform. The definitive role of dynamic preload parameters like SVV and PPV is a matter of research. Large trials in which the value of early goal-directed therapy using this technology is studied in relation to outcome are urgently needed.

Hemodynamic monitoring in the critically ill: spanning the range of kidney function

Critically ill patients often have deranged hemodynamics. Physical examination, central venous pressure, and pulmonary artery occlusion pressure ("wedge") have been shown to be unreliable at assessing volume status, volume responsiveness, and adequacy of cardiac output in critically ill patients. Thus, invasive and noninvasive cardiac output monitoring is a core feature of evaluating and managing a hemodynamically unstable patient. In this review, we discuss the various techniques and options of cardiac output assessment available to clinicians for hemodynamic monitoring in the intensive care unit. Issues related to patients with kidney disease, such as timing and location of arterial and central venous catheters and the approach to hemodynamics in patients treated by long-term dialysis also are discussed.

Comparison of values in critically ill patients for global end-diastolic volume and extravascular lung water measured by transcardiopulmonary thermodilution: a meta-analysis of the literature

INTRODUCTION

Hemodynamic parameters such as the global end-diastolic volume index (GEDVI) and extravascular lung water index (EVLWI), derived by transpulmonary thermodilution, have gained increasing interest for guiding fluid therapy in critically ill patients. The proposed normal values (680-800ml/m(2) for GEDVI and 3-7ml/kg for EVLWI) are based on measurements in healthy individuals and on expert opinion, and are assumed to be suitable for all patients. We analyzed the published data for GEDVI and EVLWI, and investigated the differences between a cohort of septic patients (SEP) and patients undergoing major surgery (SURG), respectively.

METHODS

A PubMed literature search for GEDVI, EVLWI or transcardiopulmonary single/double indicator thermodilution was carried out, covering the period from 1990 to 2010.

INTERVENTION

Meta-regression analysis was performed to identify any differences between the surgical (SURG) and non-surgical septic groups (SEP).

RESULTS

Data from 1925 patients corresponding to 64 studies were included. On comparing both groups, mean GEDVI was significantly higher by 94ml/m(2) (95%CI: [54; 134]) in SEP compared to SURG patients (788ml/m(2) 95%CI: [762; 816], vs. 694ml/m(2), 95%CI: [678; 711], p<0.001). Mean EVLWI also differed significantly by 3.3ml/kg (95%CI: [1.4; 5.2], SURG 7.2ml/kg, 95%CI: [6.9; 7.6] vs. SEP 11.0ml/kg, 95%CI: [9.1; 13.0], p=0.001).

CONCLUSIONS

The published data for GEDVI and EVLWI are heterogeneous, particularly in critically ill patients, and often exceed the proposed normal values derived from healthy individuals. In the group of septic patients, GEDVI and EVLWI were significantly higher than in the group of patients undergoing major surgery. This points to the need for defining different therapeutic targets for different patient populations.