Transpulmonary dilution-derived extravascular lung water as a measure of lung edema

Resveratrol influences pulmonary mechanics and inflammatory response in a porcine ARDS model

AIMS

Influencing the inflammatory response represents an important branch in ARDS research. The naturally occurring polyphenol derivative resveratrol has already been confirmed to have strong anti-inflammatory effects on the cardiac and metabolic system. In the present study, we investigated the propagated anti-inflammatory effects of intravenous resveratrol in a porcine ARDS model.

MAIN METHODS

20 domestic pigs (30 ± 2 kg; approval G20-1-135), divided into three groups: 1. resveratrol high dose (HD; n = 8), single bolus of 20 mg/kg over 15 min. 2. resveratrol low dose (LD; n = 8), single bolus of 10 mg/kg over 15 min. 3. Vehicle (n = 4), with the carrier solution DMSO over 15 min administered after ARDS induction. ARDS induction: using BAL/oleic acid and a subsequent test period of 8 h. Measurement parameters: Hemodynamics/spirometry data were collected continuously, BGA/laboratory parameters repetitively. Post-mortem: analysis of pulmonary inflammatory markers.

STATISTICS

Two-way analysis of variance (repeated measurement) and Student-Newman-Keuls method.

KEY FINDINGS

Resveratrol HD significantly reduced the expression of TNF-alpha in lung tissue compared to the LD group (p < 0.05). A significantly increased functional residual capacity (FRC) could be demonstrated for the HD group at the end of the test (p < 0.05 for HD vs. LD/vehicle). Further, resveratrol HD reduced statistically the EVLWI compared to LD/vehicle (p < 0.05 at T4/T8).

SIGNIFICANCE

In this study, resveratrol HD ameliorated pulmonary mechanics as reported for the FRC and EVLWI. Further, the proposed anti-inflammatory effects of resveratrol, a significant reduction in the expression of TNF-alpha was observed in the HD group.

Lung Ultrasound versus Chest X-Ray for the Detection of Fluid Overload in Critically Ill Children: A Systematic Review

Fluid overload is a common complication of critical illness, associated with increased morbidity and mortality. Pulmonary fluid status is difficult to evaluate clinically and many clinicians utilize chest X-ray (CXR) to identify fluid overload. Adult data have shown lung ultrasound (LUS) to be a more sensitive modality. Our objective was to determine the performance of LUS for detecting fluid overload, with comparison to CXR, in critically ill children. We conducted a systematic review using multiple electronic databases and included studies from inception to November 15, 2020. The sensitivity and specificity of each test were evaluated. Out of 1,209 studies screened, 4 met eligibility criteria. Overall, CXR is reported to have low sensitivity (44–58%) and moderate specificity (52–94%) to detect fluid overload, while LUS is reported to have high sensitivity (90–100%) and specificity (94–100%). Overall, the quality of evidence was moderate, and the gold standard was different in each study. Our systematic review suggests LUS is more sensitive and specific than CXR to identify pulmonary fluid overload in critically ill children. Considering the clinical burden of fluid overload and the relative ease of obtaining LUS, further evaluation of LUS to diagnose volume overload is warranted.

TIMP-2/IGFBP7 predicts acute kidney injury in out-of-hospital cardiac arrest survivors

Background

Acute kidney injury (AKI) is a common complication after cardiopulmonary resuscitation (CPR) and predicts in-hospital mortality. To which extent post-resuscitation disease or the initial event of cardiac arrest and the duration of insufficient cardiac output triggers AKI is challenging to discriminate. Knowledge on molecular mediators of AKI is scarce. Early identification of patients at high risk of AKI is hampered by the low sensitivity of the established tests in clinical routine practice. The present study aimed to determine the diagnostic utility of the novel urine biomarkers tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) for the early recognition of AKI in patients with non-traumatic shock.

Methods

The performance of [TIMP-2]·[IGFBP7] was prospectively analysed in 48 patients with shock following out-of-hospital cardiac arrest (OHCA). All patients were treated with target temperature management (TTM) for 24 h. Urinary [TIMP-2]·[IGFBP7] samples were collected at 3 and 24 h after determination of OHCA.

Results

Patients (n = 31 (65%)) developed AKI after an average of 26 ± 12 h. Patients who developed AKI had significantly higher [TIMP-2]·[IGFBP7] compared to individuals that did not develop AKI (1.52 ± 0.13 vs. 0.13 ± 0.14; p < 0.05) as early as 3 h after determination of OHCA,. For urine [TIMP-2]*[IGFBP7], the area under the curve (AUC) for the development of AKI was 0.97 (CI 0.90–1.00) at 3 h after OHCA. The optimal [TIMP-2]·[IGFBP7] cut-off value for the prediction of AKI was 0.24. The sensitivity was 96.8% and specificity was 94.1%.

Conclusions

Urinary [TIMP-2]•[IGFBP7] reliably predicts AKI in high-risk patients only 3 h after determination of OHCA with a cut-off at 0.24. This novel test may help to identify patients at high risk of AKI to enrol into clinical studies to further elucidate the pathophysiology of AKI and devise targeted interventions in the future.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2042-9) contains supplementary material, which is available to authorized users.

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.

Influence of different infracardial positions of central venous catheters in hemodynamic monitoring using the transpulmonal thermodilution method

Hemodynamic measurements are often conducted by the transpulmonary thermodilution (TPTD)-based PiCCO(®)-system. This requires a central-venous (CVC) and a thermistor-tipped arterial catheter, usually placed in the femoral artery. In certain clinical situations, CVC devices have to be placed in the inferior vena cava. However, little is known about the influence of different CVC positions (i.e. ipsi- vs. contra-lateral to the arterial catheter) on the accuracy of the TPTD measurement results. In this prospective observational study surgical intensive care unit patients who had been inserted with CVCs either into the superior (CVCVCS) or the inferior vena cava (CVCinf) in addition to an arterial PiCCO(®)-catheter, were enrolled. Patients were then divided into two groups: Group I was provided with a CVC in the contralateral (CVCcontra) and Group II in the ipsilateral (CVCipsi) inferior vena cava. Thermodilution via injection of ice-cold saline was then performed via CVCsup and CVCinf. Bland-Altman analysis for cardiac index (CI), extra-vascular lung water index (EVLWI) and global end-diastolic volume index (GEDVI) were employed. Additional correction formulas for femorally assed parameters were determined. In a total of 28 patients, bias (limits of agreement) for measurements of CI in CVCcontra was found to be +0.2 (-0.4; +0.9) and +0.3 (-0.4; +1.0) L/min/m(2) in CVCipsi. GEDVI showed a bias of +274.8 (-47.3; +596.9) mL/m(2) in CVCcontra and +274.7 (-100.7; +650.1) mL/m(2) in CVCipsi. The mean EVLWI were 9.4 ± 4.3 mL/kg for EVLWIVCS and 10.7 ± 5.2 mL/kg for EVLWIinf. The LoA yielded at -3.4 and +6.1 mL/kg with a bias of +1.3 mL/kg. Percentage errors revealed clinically acceptable limits for CI and GEDVI, but not for EVLWI. Using TPTD via an infracardial central vein, measurements of CI showed high accuracy and precision while GEDVI measurements were precise with a lower accuracy, irrespective of the position of the infracardial CVC.

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.

An inhaled tumor necrosis factor-alpha-derived TIP peptide improves the pulmonary function in experimental lung injury

INTRODUCTION

The lectin-like domain of TNF-α enhances the fluid clearance across the alveolar barrier. For experimental purposes, the lectin-like domain can be mimicked by a synthetic peptide representing the TIP-motif of TNF-α. The present study aims to assess the acute effect of TIP on the pulmonary function in a porcine model of acute respiratory distress syndrome (ARDS).

METHODS

Lung injury was induced in 16 pigs (25-27 kg) by bronchoalveolar lavage followed by injurious ventilation. Following randomisation, either nebulised TIP (1 mg/kg; AP301, APEPTICO, Vienna, Austria) or water for injection (control group) was administered. During 5 h of monitoring, the extravascular lung water index (EVLWI), the quotient of partial pressure of oxygen and inspired oxygen concentration (PaO(2) /FiO(2) ) and the pulmonary shunt fraction were repetitively assessed. The data were evaluated by an analysis of variance including Bonferroni-Holm correction.

RESULTS

Comparable baseline conditions in both groups were achieved. Ventilatory parameters were standardised in both groups. In the TIP group, a significant reduction of the EVLWI and a simultaneous increase in the PaO(2) /FiO(2) ratio was shown (each P < 0.0001). No changes in the control group were observed (EVLWI: P = 0.43, PaO(2) /FiO(2) : P = 0.60). The intergroup comparison demonstrates a significant advantage of TIP inhalation over placebo (EVLWI: P < 0.0001, PaO(2) /FiO(2) : P = 0.004, shunt fraction: P = 0.0005).

CONCLUSIONS

The inhalation of TIP induces an amelioration of clinical surrogate parameters of the lung function in a porcine lung injury model. By mimicking the lectin-like domain, the synthetic TIP peptide AP301 is an innovative approach as supportive therapy in ARDS.

Predictors of pulmonary edema formation during fluid loading in the critically ill with presumed hypovolemia*

OBJECTIVES

It is largely unknown why extravascular lung water may increase during fluid loading in the critically ill with presumed hypovolemia. In this study we evaluated the hemodynamic predictors of such an increase.

DESIGN

A prospective observational study.

PATIENTS

Sixty-three presumed hypovolemic mechanically ventilated patients (22 septic and 41 nonseptic patients).

INTERVENTION

Fluid loading with saline or colloid fluids guided by (changes in) cardiac filling pressures.

MEASUREMENTS AND MAIN RESULTS

Before and after fluid-loading, hemodynamic and respiratory variables were recorded, including variables obtained by transpulmonary dilution such as cardiac index, pulmonary blood volume index, and extravascular lung water. Baseline parameters and change in parameters were compared between patients with a change in extravascular lung water <10% and patients with a change in extravascular lung water ≥ 10%. Predictive values for change in extravascular lung water ≥ 10% were evaluated. Baseline cardiac index and pulmonary blood volume index were higher, whereas change in cardiac index, change in pulmonary blood volume index, and change in PaO2/FIO2 ratio were lower in patients with a change in extravascular lung water ≥ 10% than in patients with a change in extravascular lung water <10%. The change in extravascular lung water correlated to baseline cardiac index (r = 0.17; p = .001), baseline pulmonary blood volume index (r = 0.15; p = .001), change in pulmonary blood volume index (r = 0.16; p < .001), and change in PaO2/FIO2 ratio (r = 0.13; p = .004). In multiple logistic regression analysis baseline cardiac index, baseline pulmonary blood volume index, the change in cardiac index, change in pulmonary blood volume index, and change in PaO2/FIO2 ratio individually contributed to prediction of a change in extravascular lung water ≥ 10%, independent of the presence of sepsis, pulmonary vascular permeability, and cardiac filling pressures. A change in extravascular lung water ≥ 10% was predicted by baseline cardiac index (77% sensitivity, 98% specificity) and pulmonary blood volume index (92% sensitivity, 68% specificity), and by change in cardiac index (69% sensitivity, 59% specificity), change in pulmonary blood volume index (77% sensitivity, 82% specificity), and change in PaO2/FIO2 ratio (77% sensitivity, 66% specificity).

CONCLUSION

Extravascular lung water increase during fluid loading in the critically ill is predicted by a plateau of cardiac function and pulmonary vascular filling at baseline, rather than by pulmonary vascular permeability and filling pressures. Increasing extravascular lung water is further reflected by a decrease of PaO2/FIO2 ratio. These observations may help preventing pulmonary fluid overloading.

Nasal potential difference to detect Na+ channel dysfunction in acute lung injury

Pulmonary fluid clearance is regulated by the active transport of Na(+) and Cl(-) through respiratory epithelial ion channels. Ion channel dysfunction contributes to the pathogenesis of various pulmonary fluid disorders including high-altitude pulmonary edema (HAPE) and neonatal respiratory distress syndrome (RDS). Nasal potential difference (NPD) measurement allows an in vivo investigation of the functionality of these channels. This technique has been used for the diagnosis of cystic fibrosis, the archetypal respiratory ion channel disorder, for over a quarter of a century. NPD measurements in HAPE and RDS suggest constitutive and acquired dysfunction of respiratory epithelial Na(+) channels. Acute lung injury (ALI) is characterized by pulmonary edema due to alveolar epithelial-interstitial-endothelial injury. NPD measurement may enable identification of critically ill ALI patients with a susceptible phenotype of dysfunctional respiratory Na(+) channels and allow targeted therapy toward Na(+) channel function.

Global end-diastolic volume, serum osmolarity, and albumin are risk factors for increased extravascular lung water

BACKGROUND

The transpulmonary thermodilution technique allows the determination of cardiac preload (global end-diastolic volume index) and quantification of pulmonary edema (extravascular lung water index [EVLWI]). Pulmonary edema commonly develops in critically ill patients; however, the underlying pathophysiology, that is, hydrostatic (cardiac) or permeability-induced (noncardiac), often remains unclear. In this study, hemodynamic and serum parameters of osmolarity and oncotic pressure were analyzed to identify risk factors for increased EVLWI.

METHODS

A retrospective, single-center analysis in an intensive care unit of a university hospital was performed. No interventions were made for the study. Forty-two critically ill patients were included, and 126 simultaneous hemodynamic measurements and serum determinations were analyzed by logistic regression and Spearman rank correlation coefficient analysis.

RESULTS

Global end-diastolic volume index (P = .001), serum albumin (P = .006), and serum osmolarity (P = .029) were significant factors for increased EVLWI (defined as >10 mL/kg).

CONCLUSION

Hypervolemia, hypoalbuminemia, and high plasma osmolarity are associated with increased EVLWI.

Transpulmonary thermodilution using femoral indicator injection: a prospective trial in patients with a femoral and a jugular central venous catheter

Introduction

Advanced hemodynamic monitoring using transpulmonary thermodilution (TPTD) is established for measurement of cardiac index (CI), global end-diastolic volume index (GEDVI) and extra-vascular lung water index (EVLWI). TPTD requires indicator injection via a central venous catheter (usually placed via the jugular or subclavian vein). However, superior vena cava access is often not feasible due to the clinical situation. This study investigates the conformity of TPTD using femoral access.

Methods

This prospective study involved an 18-month trial at a medical intensive care unit at a university hospital. Twenty-four patients with both a superior and an inferior vena cava catheter at the same time were enrolled in the study.

Results

TPTD-variables were calculated from TPTD curves after injection of the indicator bolus via jugular access (TPTDjug) and femoral access (TPTDfem). GEDVIfem and GEDVIjug were significantly correlated (r_m = 0.88; P < 0.001), but significantly different (1,034 ± 275 vs. 793 ± 180 mL/m²; P < 0.001). Bland-Altman analysis demonstrated a bias of +241 mL/m² (limits of agreement: -9 and +491 mL/m²). GEDVIfem, CIfem and ideal body weight were independently associated with the bias (GEDVIfem-GEDVIjug). A correction formula of GEDVIjug after femoral TPTD, was calculated. EVLWIfem and EVLWIjug were significantly correlated (r_m = 0.93; P < 0.001). Bland-Altman analysis revealed a bias of +0.83 mL/kg (limits of agreement: -2.61 and +4.28 mL/kg). Furthermore, CIfem and CIjug were significantly correlated (r_m = 0.95; P < 0.001). Bland-Altman analysis demonstrated a bias of +0.29 L/min/m² (limits of agreement -0.40 and +0.97 L/min/m²; percentage-error 16%).

Conclusions

TPTD after femoral injection of the thermo-bolus provides precise data on GEDVI with a high correlation, but a self-evident significant bias related to the augmented TPTD-volume. After correction of GEDVIfem using a correction formula, GEDVIfem shows high predictive capabilities for GEDVIjug. Regarding CI and EVLWI, accurate TPTD-data is obtained using femoral access.

Redistribution of pulmonary blood flow impacts thermodilution-based extravascular lung water measurements in a model of acute lung injury

BACKGROUND

Studies using transthoracic thermodilution have demonstrated increased extravascular lung water (EVLW) measurements attributed to progression of edema and flooding during sepsis and acute lung injury. The authors hypothesized that redistribution of pulmonary blood flow can cause increased apparent EVLW secondary to increased perfusion of thermally silent tissue, not increased lung edema.

METHODS

Anesthetized, mechanically ventilated canines were instrumented with PiCCO (Pulsion Medical, Munich, Germany) catheters and underwent lung injury by repetitive saline lavage. Hemodynamic and respiratory physiologic data were recorded. After stabilized lung injury, endotoxin was administered to inactivate hypoxic pulmonary vasoconstriction. Computed tomographic imaging was performed to quantify in vivo lung volume, total tissue (fluid) and air content, and regional distribution of blood flow.

RESULTS

Lavage injury caused an increase in airway pressures and decreased arterial oxygen content with minimal hemodynamic effects. EVLW and shunt fraction increased after injury and then markedly after endotoxin administration. Computed tomographic measurements quantified an endotoxin-induced increase in pulmonary blood flow to poorly aerated regions with no change in total lung tissue volume.

CONCLUSIONS

The abrupt increase in EVLW and shunt fraction after endotoxin administration is consistent with inactivation of hypoxic pulmonary vasoconstriction and increased perfusion to already flooded lung regions that were previously thermally silent. Computed tomographic studies further demonstrate in vivo alterations in regional blood flow (but not lung water) and account for these alterations in shunt fraction and EVLW.

Extravascular lung water measurement using transpulmonary thermodilution in children

OBJECTIVE

Measurement of extravascular lung water (EVLW) may be useful in the treatment of critically ill children and can be performed at the bedside using the transpulmonary thermodilution technique (TPTD). There are currently no data to verify the accuracy of these measurements in (small) children. We compared the results of TPTD measurement with the clinical gold standard transpulmonary double indicator dilution (TPDD) measurement in young children.

DESIGN

Prospective clinical study in children.

SETTING

Catheterization laboratory of a university hospital.

PATIENTS AND METHODS

Twelve children (<2 yrs or <12 kg) under general anesthesia.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Measurements were performed using injections of ice-cold indicator (saline or dye) through a central venous catheter. Mean cardiac index was 3.91 L/min/m, mean intrathoracic blood volume index (ITBVITPDD) was 614.9 mL/m, and mean extravascular lung water index (EVLWITPDD) was 11.7 mL/kg. The correlation coefficient between EVLWITPDD and EVLWITPTD is 0.96 (95% confidence interval: 0.87-0.99; p < 0.0001). Bland-Altman analysis for EVLW measurements showed a mean bias of 2.34 mL/kg (18.13%) and limits of agreement +/-2.97 mL/kg (19.78%). The difference between measurements via the right atrium compared with the femoral vein was 2.8% for cardiac output, 8.2% for global end-diastolic volume, and 0.1% for EVLW.

CONCLUSION

Clinical measurement of EVLW in young children can be performed using the TPTD with the injection catheter inserted in the femoral vein. Further studies are needed to clarify the clinical value of these measurements.