Extravascular Lung Water In Patients Research Articles

Lung Ultrasound Reproducibly Outperforms Computed Tomography in the Detection of Extravascular Lung Water in Patients Undergoing Haemodialysis.

Lung ultrasound (LUS) is increasingly used as an extension of physical examination, informing clinical diagnosis, and decision making. There is particular interest in the assessment of patients with pulmonary congestion and extravascular lung water, although gaps remain in the evidence base underpinning this practice as a result of the limited evaluation of its inter-rater reliability and comparison with more established radiologic tests. 30 patients undergoing haemodialysis were prospectively recruited to an observational cohort study (NCT01949402). Patients underwent standardised LUS assessment before, during and after haemodialysis; their total LUS B-line score was generated, alongside a binary label of whether appearances were consistent with an interstitial syndrome. LUS video clips were recorded and independently scored by two blinded expert clinician sonographers. Low-dose non-contrast thoracic CT, pre- and post dialysis, was used as a "gold standard" radiologic comparison. LUS detected a progressive reduction in B-line scores in almost all patients undergoing haemodialysis, correlating with the volume of fluid removed once individuals with no or minimal B-lines upon pre-dialysis examination were discounted. When comparing CT scans pre- and post dialysis, radiologic evidence of the change in fluid status was only identified in a single patient. This is the first study to demonstrate that LUS detects changes in extravascular lung water caused by changing fluid status during haemodialysis using a blinded outcome assessment and that LUS appears to be more sensitive than CT for this purpose. Further research is needed to better understand the role of LUS in this and similar patient populations, with the aim of improving clinical care and outcomes.

Evaluation of extravascular lung water in patients with acute respiratory distress syndrome by syndecan-1 combined with lung ultrasonography

To investigate the value of plasma syndecan-1 (SDC-1) combined with lung ultrasonography in evaluating the degree of extravascular lung water in patients with acute respiratory distress syndrome (ARDS). From July 2018 to July 2019, 50 patients with ARDS admitted to the department of intensive care unit of Wuxi People's Hospital Affiliated to Nanjing Medical University were enrolled. After admission, pulse indicator continuous cardiac output (PiCCO) catheter was established for all patients. PiCCO indexes, including extravascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI) were monitored by one doctor. Another doctor performed lung ultrasound examination, and calculated the sum of the number of B-lines under 10 ultrasound sections of upper blue point, lower blue point, diaphragm point, Plaps point and rear blue point of both lungs. Then the level of plasma SDC-1 was detected by enzyme linked immunosorbent assay (ELISA). Pearson correlation method was used to analyze the correlation between the number of ultrasonic B-lines, plasma SDC-1 level and EVLWI and PVPI. Taking 10 mL/kg EVLWI as the boundary value, the degree of pulmonary edema in patients with ARDS was divided into mild pulmonary edema and severe pulmonary edema. The receiver operator characteristic curve (ROC curve) was drawn, and the number of B-lines, SDC-1 and the predictive value of the combination of the above two indicators on the severity of pulmonary edema in patients with ARDS were analyzed. The cardiac index (CI) and central venous pressure (CVP) of 50 patients with ARDS were (46.84±6.00) mL×s-1×m-2 and (8.12±1.80) mmHg (1 mmHg = 0.133 kPa), cardiogenic pulmonary edema was excluded. In 50 patients with ARDS, EVLWI was (10.82±2.92) mL/kg, PVPI was 3.02±0.69, the number of ultrasound B-lines was 40.90±13.05, and plasma SDC-1 was (568.25±118.14) μg/L. Pearson correlation analysis showed that the number of ultrasound B-lines in patients with ARDS was significantly positively correlated with EVLWI and PVPI (r1 = 0.802, r2 = 0.799, both P < 0.01). Plasma SDC-1 was also positively correlated with EVLWI and PVPI (r1 = 0.732, r2 = 0.576, both P < 0.01). ROC curve analysis showed that the number of B-lines and SDC-1 had good predictive value for the severity of pulmonary edema in patients with ARDS. The area under ROC curve (AUC) and 95% confidence interval (95%CI) were 0.891 (0.803-0.979) and 0.875 (0.772-0.978), respectively. When the cut-off of B-lines was 40.50, the sensitivity and specificity were 82.1% and 86.4%, respectively. When the cut-off of SDC-1 was 559.37 μg/L, the sensitivity and specificity were 85.7% and 81.8%, respectively. Combining the number of B-lines with SDC-1 could further improve the predictive value of pulmonary water in patients with ARDS. The AUC (95%CI) was 0.958 (0.890-1.000), and the sensitivity and specificity were 92.9% and 91.8%, respectively. The level of plasma SDC-1 and the number of pulmonary ultrasonic B-lines have a good correlation with the degree of extravascular lung water in patients with ARDS. The combined application of the two noninvasive indexes can be used to evaluate the degree of extravascular lung water in patients with ARDS.

Assessment of extravascular lung water by measuring the number of pulmonary ultrasound B-lines before and after CBP in patients with MODS.

To determine whether the change in the number of pulmonary ultrasound B-line can accurately assess the extravascular lung water (EVLW) before and after continuous bedside blood purification (CBP) in patients with multiple organ dysfunction syndrome (MODS).Seventy-six patients with MODS who underwent CBP were examined within 24 hours before and after CBP using pulmonary ultrasound to detect the number of ultrasound B-line or using pulse indicator continuous cardiac output method to examine extravascular lung water, blood oxygenation index, and B-type natriuretic peptide (BNP) content. The correlation of the change in the number of B lines before and after CBP treatment with the negative balance of 24 hours liquid, the change of oxygenation index, and BNP content were analyzed.In the 76 patients, CBP treatment significantly decreased EVLW, the number of B-line, and BNP (P < .05 for all), while it significantly increased the oxygenation index (P < .05). Correlation analysis showed that the decrease in B-line number after CBP treatment was positively correlated with the 24 hours negative lung fluid balance, decrease of EVLW, oxygenation index improvement, and decreased BNP content. The change in the numbers of pulmonary ultrasound B-line can accurately assess the change of EVLW before and after CBP treatment and reflect the efficiency of ventilation in the lungs and the risk of heart failure.Thus, it can replace pulse indicator continuous cardiac output as an indicator for evaluating EVLW in patients with MODS treated with CBP.

Association between lung comets and subendocardial viability ratio in peritoneal dialysis patients.

Pulmonary congestion is a direct result of either general overhydration or cardiac dysfunction. Lung ultrasonography (LUS) with lung B-lines (LUS comets) can be used to assess extravascular lung water in patients with end-stage renal disease on hemodialysis or peritoneal dialysis (PD). Subendocardial viability ratio (SEVR) is a pulse wave analysis parameter that is a non-invasive measure of coronary perfusion and is related to cardiac work and oxygen consumption. Our aim was to investigate the association between LUS comets and SEVR in PD patients. We performed an observational study in 25 PD patients in a single dialysis center. Extravascular lung water was quantified by the number of LUS comets, using a portable ultrasound (US) device. LUS comets were recorded in each intercostal space and defined as hyperechoic US bundles at a narrow base extending from the transducer to the edge of the screen. The sum of LUS comets yields a score reflecting the extent of water accumulation in the lungs. SEVR was determined non-invasively by radial applanation tonometry. Mean age of patients was 54.7 ± 10.7 years, mean PD vintage 27 ± 33 (1 - 167) months, 60% were men. The mean number of LUS comets was 13 ± 19 (0 - 71), and the mean SEVR was 153 ± 40%. We found a statistically significant negative correlation between the number of LUS comets and SEVR (r = -0.467; p = 0.019). Multiple regression analysis with LUS comets as dependent variable, and SEVR and age as independent variables showed a statistically significant relationship between SEVR and the number of LUS comets (β = -0.467, p = 0.021). Higher number of LUS comets is associated with lower SEVR in PD patients.

Lung ultrasound, hemoglobin, and NT-proBNP in peritoneal dialysis patients

Lung ultrasound (LUS) is a non-invasive technique for estimating extravascular lung water in patients with end-stage renal disease and heart diseases. In this study, we examined an association between the severity of lung congestion as detected by LUS B-lines (LUS comets), anemia, and serum biomarker N-terminal pro-brain natriuretic peptide (NT-proBNP) in peritoneal dialysis (PD) patients. 19 patients, who were treated with PD in our dialysis center were enrolled. On the day of their routine check-up, we performed a lung auscultation, LUS on 28 typical locations and determined blood levels of hemoglobin and NT-proBNP. The average age of patients was 54 (range 30 - 71) years, the average duration of PD treatment was 53 (range 10 - 194) months, 63% (12) of the patients were male. Nine (47.4%) patients had peripheral edema, and only 1 (5.3%) patient had inspiratory crackles. Using LUS, we found mean 17 (range 1 - 87) lung comets. Mean hemoglobin level was 108.6 g/L (SD ± 10.4), mean NT-proBNP level 1,151 pmol/L (SD ± 1,077). We found a statistically significant correlation between the number of lung comets and hemoglobin level (r = -0.655; p = 0.002) and NT-proBNP (r = 0.759; p < 0.0001). Multiple regression analysis with the number of lung comets as dependent variable and hemoglobin and NT-proBNP levels as independent variables confirmed a statistically significant association between the number of lung comets and NT-proBNP (β = 0.572; p = 0.009). In PD patients, the number of LUS comets is associated with hemoglobin and NT-proBNP.

Role of lung ultrasound in estimation of extravascular lung water in patients on regular hemodialysis

Role of lung ultrasound in estimation of extravascular lung water in patients on regular hemodialysis

Application of lung ultrasound surface wave elastography for assessment of extravascular lung water in patients hospitalized with congestive heart failure

Lung ultrasound (LUS) detects the presence of extravascular lung water (EVLW) through the visualization of B-Line artifacts. However, the qualitative nature of LUS limits its effectiveness in serial or longitudinal studies such as evaluating changes in EVLW at different time points in patients undergoing diuretic therapy for congestive heart failure. Lung ultrasound surface wave elastography (LUSWE) is a novel technique using a small handheld device that can measure superficial lung tissue elastic properties. We aimed to evaluate the use of LUSWE to measure quantitative changes in lung elasticity caused by acute changes in EVLW. We performed LUSWE on consecutive days in 14 patients hospitalized for acute congestive heart failure with evidence of pulmonary edema (clinical EVLW). From day#1 to day#2, the patients had an average diuresis of net negative 2.1 l associated with an average decrease in 13 B-Lines by lung ultrasound, signifying a reduction in EVLW. LUSWE analysis demonstrated a significant reduction (p < 0.05) in surface wave velocity in all interrogated intercostal spaces from day#1 to day#2. In summary, LUSWE performed at the bedside was able to demonstrate improvement in lung compliance (decreased elasticity) correlating with a reduction in EVLW in hospitalized patients being treated for congestive heart failure.

Alveolar recruitment maneuver attenuates extravascular lung water in acute respiratory distress syndrome.

Background:The alveolar recruitment maneuver (RM) has been reported to improve oxygenation in acute respiratory distress syndrome (ARDS) and may be related to reduced extravascular lung water (EVLW) in animals. This study was designed to investigate the effects of RM on EVLW in patients with ARDS.Methods:An open label, prospective, randomized controlled trial including patients with ARDS was conducted in hospitals in North Taiwan between 2010 and 2016. The patients were divided into 2 groups (with and without RM). The primary endpoint was the comparison of the EVLW index between the 2 groups.Results:Twenty-four patients with ARDS on mechanical ventilator support were randomized to receive ventilator treatment with RM (RM group, n = 12) or without RM (non-RM group, n = 12). Baseline demographic characteristics were similar between the 2 groups. After recruitment, the day 3 extravascular lung water index (EVLWI) (25.3 ± 9.3 vs 15.5 ± 7.3 mL/kg, P = .008) and the arterial oxygen tension/fractional inspired oxygen ratio (PaO2/FiO2) (132.3 ± 43.5 vs 185.6 ± 38.8 mL/kg, P = .003) both improved over that of day 1. However, both EVLWI and PaO2/FiO2 did not significantly change from day 1 to 3 in the non-RM group.Conclusion:RM is a feasible method for improving oxygenation and the EVLW index in patients with ARDS, as well as for decreasing ventilator days and intensive care unit stay duration.

Effect of rhubarb on extravascular lung water in patients with acute respiratory distress syndrome.

The aim of this study was to evaluate the effect of rhubarb on extravascular lung water (EVLW) in patients with acute respiratory distress syndrome (ARDS). A total of 80 patients with ARDS were randomly divided into a treatment group (40 cases) and control group (40 cases). Patients in the treatment group received rhubarb (30.0 g/d) and patients in the control group received conventional therapy for seven consecutive days. Extravascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI) were determined using pulse contour cardiac output (PiCCO) technology, and the oxygenation index was measured by blood gas analysis at baseline and on days 3, 5 and 7 after treatment. The oxygenation index was higher and the levels of EVLWI and PVPI were lower after treatment in the two groups; however, these indexes showed significant differences on the 5th and 7th days after rhubarb treatment compared with the results in the control group (p<0.05). Rhubarb can decrease EVLWI and PVPI, and improve oxygenation in patients with ARDS.

GW27-e0480 Clinical effects of Xinmailong injection on the cardiac function and extravascular lung water in patients with acute heart failure

To observe the effects of Xinmailong injection on the cardiac function and extravascular lung water in patients with acute heart failure. 43 AHF patients were randomly divided into the Xinmailong treatment group(n=20) and the control group(n=23). The two groups were both given routine treatment of

Ultrasound assessment for extravascular lung water in patients with septic shock

Extravascular lung water (EVLW) refers to fluid within the lung but outside the vascular compartment. Increment of EVLW was associated with mortality in critically ill patients. Extravascular lung water index (EVLWI) >10 ml/kg was found in patients with cardiogenic pulmonary edema and correlated with pulmonary capillary wedge pressure >20 mmHg. Measurement of EVLW needs sophisticated tools and an invasive method by transpulmonary thermodilution (TPTD) technique. In contrast, multiple B-lines by lung ultrasound (LUS) have been recently proposed to correlate with increased EVLW in patients with pulmonary edema. This study aims to compare three methods of LUS and EVLWI measured by TPTD to assess pulmonary edema in patients with septic shock.

The effect of high-frequency oscillatory ventilation combined with tracheal gas insufflation on extravascular lung water in patients with acute respiratory distress syndrome: A randomized, crossover, physiologic study

PurposeHigh-frequency oscillation combined with tracheal gas insufflation (HFO-TGI) improves oxygenation in patients with acute respiratory distress syndrome (ARDS). There are limited physiologic data regarding the effects of HFO-TGI on hemodynamics and pulmonary edema during ARDS. The aim of this study was to investigate the effect of HFO-TGI on extravascular lung water (EVLW). Materials and methodsWe conducted a prospective, randomized, crossover study. Consecutive eligible patients with ARDS received sessions of conventional mechanical ventilation with recruitment maneuvers (RMs), followed by HFO-TGI with RMs, or vice versa. Each ventilatory technique was administered for 8 hours. The order of administration was randomly assigned. Arterial/central venous blood gas analysis and measurement of hemodynamic parameters and EVLW were performed at baseline and after each 8-hour period using the single-indicator thermodilution technique. ResultsTwelve patients received 32 sessions. Pao2/fraction of inspired oxygen and respiratory system compliance were higher (P < .001 for both), whereas extravascular lung water index to predicted body weight and oxygenation index were lower (P = .021 and .029, respectively) in HFO-TGI compared with conventional mechanical ventilation. There was a significant correlation between Pao2/fraction of inspired oxygen improvement and extravascular lung water index drop during HFO-TGI (Rs = −0.452, P = .009). ConclusionsHigh-frequency oscillation combined with tracheal gas insufflation improves gas exchange and lung mechanics in ARDS and potentially attenuates EVLW accumulation.

Global end-diastolic volume is an important contributor to increased extravascular lung water in patients with acute lung injury and acuterespiratory distress syndrome: a multicenter observational study.

BackgroundExtravascular lung water (EVLW), as measured by the thermodilution method, reflects the extent of pulmonary edema. Currently, there are no clinically effective treatments for preventing increases in pulmonary vascular permeability, a hallmark of lung pathophysiology, in patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS). In this study, we examined the contributions of hemodynamic and osmolarity factors, for which appropriate interventions are expected in critical care, to EVLW in patients with ALI/ARDS.MethodsWe performed a subgroup analysis of a multicenter observational study of patients with acute pulmonary edema. Overall, 207 patients with ALI/ARDS were enrolled in the study. Multivariate regression analysis was used to evaluate the associations of hemodynamic and serum osmolarity parameters with the EVLW index (EVLWI; calculated as EVLW/Ideal body weight). We analyzed factors measured on the day of enrollment (day 0), and on days 1 and 2 after enrollment.ResultsMultivariate regression analysis showed that global end-diastolic volume index (GEDVI) was significantly associated with EVLWI measured on days 0, 1, and 2 (P = 0.002, P < 0.001, and P = 0.003, respectively), whereas other factors were not significantly associated with EVLWI measured on all 3 days.ConclusionsAmong several hemodynamic and serum osmolarity factors that could be targets for appropriate intervention, GEDVI appears to be a key contributor to EVLWI in patients with ALI/ARDS.Trial registrationUniversity Hospital Medical Information Network (UMIN) Clinical Trials Registry UMIN000003627.

Research in the role of extravascular lung water in patients with sepsis-induced ALI/ARDS

Objective To investigate and compare the change of extravascular lung water (EVLW) and levels of cytokines in septic patients without clinical acute lung injury (ALI) /acute respiratory distress syndrome (ARDS) with those in spetic patients with sepsis-induced ALI/ARDS in order to determine the role of EVLW involved in the pathogenesis of lung injury in the patients by quantifying the relationship between EVLW and biomarkers of lung injury in patients with sepsis.Methods A total of 40 septic patients complicated either with or without clinical ALI/ARDS after sepsis. In each patient,transpulmonary thermodilution (PiCCO) was used to measure cardiovascular hemodynamics and EVLWI for 7 days via an arterial cannula indwelled within 72 hours after diagnosis of severe sepsis was made, and serial bronchoalveolar lavages (BAL) were carried out.Other examinations including blood gas analysis,ventilator parameters,chest X-ray and the levels of pro-inflammatory cytokines such as tumor necrosis factor (TNF-oα),interleukin-1 in the BAL were recorded.In-hospital and ICU mortalities were also observed.Results Of total 40 patients,29 were complicated with clinically defined septic ALI/ARDS ( ARDS n =15,and ALI n =14).The septic patients complicated with ALL/ARDS had significantly higher amount of EVLWI and higher levels of TNF-α and interleukin-1 in the BAL than patients without ALI/ARDS ( P ＜ 0.05).The arterial oxygen tension/fractional inspired oxygen ratio,lung injury score,and the levels of TNF-α,IL-1 in the BAL correlated with EVLWI.Moreover,in-hospital mortality,ICU mortality and the length of ICU stay of the patients with high amount of EVLWI were markedly increased than those of patients with low amount of EVLWI. Conclusions In septic patients complicated with ALI/ARDS, the extravascular lung water index correlates with oxygenation,lung injury severity and inflammatory cytokines in lung.Determination of EVLWI may be useful for evaluation of severity of lung injury and prognosis of septic patients. Key words: Severe sepsis; Acute lung injury; Acute respiratory distress syndrome; Extravascularlung water; Cytokines

Influence of Extravascular Lung Water Determination in Fluid and Vasoactive Therapy

Preload parameters in postresuscitation phase are not sufficiently sensitive to guide fluid therapy in critically ill patients. We analyzed modifications in the fluid therapy and vasoactive drugs of critically ill patients that were produced by inclusion of extravascular lung water (EVLW) data in the treatment protocol and evaluated the short-term response. This observational and prospective study included consecutive patients with hypotension or hypoxemia, comparing the therapeutic plan for fluid and vasoactive drug treatment between before and after knowing the EVLW value. We studied 42 patients. After knowing the EVLW, 52.4% (n = 22) of initial therapeutic plans were changed, modifying fluid therapy in all of these cases and vasoactive therapy in 22% of them. EVLW value was 13.91 +/- 5.62 in patients with change of therapeutic plan versus 10 +/- 4.52 in those with no change (p < 0.05). No differences were found in preload parameters as a function of change/no change. The most frequent decision change (n = 13) was to fluid reduction plus diuretic administration, and patients with this modification had significantly (p < 0.05) higher EVLW values compared with the remaining patients with a change in fluid therapy. Out of the 22 patients with a modified therapeutic decision, the therapy proved effective in 18 patients Quantification of EVLW in patients who can be considered euvolemic induces important modifications in fluid and vasoactive therapy. These changes generally resulted in a lower volume loading and a positive outcome for the patient.

A study on the effect of recruitment maneuver imposed on extravascular lung water in patients with acute respiratory distress syndrome

To investigate the possible effects of recruitment maneuver (RM) imposing on extravascular lung water (EVLW) in patients with acute respiratory distress syndrome (ARDS). Twenty patients with ARDS who were eligible for the study were randomized to two groups, one group of which received regular therapy+RM (RM group), and to the other group only regular therapy was given (control group). Mechanical ventilation of all the patients was performed on the principles of lung protective ventilation. RM was carried out in bi-level positive airway passage (BIPAP) mode, and repeated every 8 hours per day until on the 7th day or before weaning of mechanical ventilation. The treatment was same between the two groups except RM. Baseline data and the influencing factors of EVLW were all recorded, which included everyday EVLW, extravascular lung water index (EVLWI) after RM, respiratory mechanics, oxygenation parameters, central venous pressure (CVP), plasma colloid osmotic pressure (COP), dosage of corticosteroid and adrenergic drugs, 24-hour net fluid balance. EVLW and EVLWI in RM and control group showed a tendency of decrease with passage of time, but the difference between both groups had no statistical significance (all P>0.05). The comparisons between the influencing factors of the groups, consisting of CVP, COP, noradrenaline and hydrocortisone, had no significant difference either (all P>0.05). Dopamine dosage in RM group on the 4th day was smaller than that of control group (P<0.05). Net fluid balance in RM group on the 7th day was negative, whereas it was positive in control group (P<0.05). Mean airway pressure [Pmean, RM group (18.8+/-3.2) cm H(2)O (1 cm H(2)O=0.098 kPa) vs. control group (16.6+/-3.9) cm H(2)O] and lung quasi-static compliance [Cstat, RM group (36.5+/-14.5) ml/cm H(2)O vs. control group (29.3+/-12.0) ml/cm H(2)O] in RM group were higher than those in control group (both P<0.05). Cstat on the 5th day was higher than that on the 2nd and 3rd day in RM group (both P<0.05). But oxygenation index (PaO(2)/FiO(2)) showed no distinct difference between the groups (all P>0.05). RM for the patients with ARDS can merely improve lung mechanics without obvious effect on EVLW. Neither of the influencing factors involved in the study has impact on emergence and clearance of EVLW.

Alcohol Abuse Enhances Pulmonary Edema in Acute Respiratory Distress Syndrome

Pulmonary edema is a cardinal feature of the life-threatening condition known as acute respiratory distress syndrome (ARDS). Patients with chronic alcohol abuse are known to be at increased risk of developing and dying from ARDS. Based upon preclinical data, we hypothesized that a history of chronic alcohol abuse in ARDS patients is associated with greater quantities and slower resolution of pulmonary edema compared with ARDS patients without a history of alcohol abuse. A PiCCO transpulmonary thermodilution catheter was inserted into 35 patients within 72 hours of meeting American European Consensus Criteria definition of ARDS. Pulmonary edema was quantified as extravascular lung water (EVLW) and measured for up to 7 days in 13 patients with a history of chronic alcohol abuse and 22 patients without a history of chronic alcohol abuse. Mean EVLW was higher in patients with a history of chronic alcohol abuse (16.6 vs. 10.5 ml/kg, p < 0.0001). Patients with alcohol abuse had significantly greater EVLW over the duration of the study (RM-ANOVA p = 0.003). There was a trend towards slower resolution of EVLW in patients with a history of alcohol abuse (a decrease of 0.5 ml/kg vs. 2.4 ml/kg, p = 0.17) over the study period. A history of alcohol abuse conferred a greater than 3-fold increased risk of elevated EVLW [OR 3.16, (1.26 to 7.93)] using multivariate logistic regression analysis. In patients who develop ARDS, alcohol abuse is associated with greater levels EVLW and a trend towards slower resolution of EVLW. Combined with mechanistic and preclinical evidence linking chronic alcohol consumption and ARDS, targeted therapies should be developed for these patients.

Measurement of extravascular lung water using the single indicator method in patients: research and potential clinical value

Extravascular lung water includes all of the fluid within the lung but outside of the vasculature. Lung water increases as a result of increased hydrostatic vascular pressure or from an increase in lung endothelial and epithelial permeability or both. Experimentally, extravascular lung water has been measured gravimetrically. Clinically, the chest radiograph is used to determine whether extravascular lung water is present but is an insensitive instrument for determining the quantity of lung water. Bedside measurement of extravascular lung water in patients is now possible using a single indicator thermodilution method. This review critically evaluates the experimental and clinical evidence supporting the potential value of measuring extravascular lung water in patients using the single indicator method.

Ultrasound Assessment for Extravascular Lung Water in Patients Undergoing Hemodialysis: Time Course for Resolution

Sonographic B-lines, also known as lung comets, have been shown to correlate with the presence of extravascular lung water (EVLW). Absent in normal lungs, these sonographic findings become prominent as interstitia and alveoli fill with fluid. Characterization of the dynamics of B-lines, specifically their rate of disappearance as volume is removed, has not been previously described. In this study, we describe the dynamics of B-line resolution in patients undergoing hemodialysis.Patients undergoing hemodialysis underwent three chest ultrasound examinations: before, at the midpoint, and after dialysis. We followed a previously described chest ultrasound protocol that counts the number of B-lines visualized in 28 lung zones. Baseline demographics, assessment of ejection fraction, time elapsed, net volume of fluid removed, and subjective degree of shortness of breath were recorded for each patient.Forty of 45 patients completed full dialysis runs and had all three lung scans performed; 6 of 40 patients had zero or one B-line predialysis, and none of these 6 patients gained B-lines during dialysis. Thirty-four of 40 patients had statistically significant reductions in the number of B-lines from predialysis to the midpoint scan and from predialysis to postdialysis with a p value < 0.001. There was no association between subjective dyspnea scores and number of B-lines removed.B-line resolution appears to occur real-time as fluid is removed from the body, and this change was statistically significant. These data support thoracic ultrasound as a useful method for evaluating real-time changes in EVLW and in assessing a patient's physiologic response to the removal of fluid.Massachusetts General Hospital trial registration protocol No. 2007P 002226.

Accurate characterization of extravascular lung water in acute respiratory distress syndrome*

Measurements of extravascular lung water (EVLW) correlate to the degree of pulmonary edema and have substantial prognostic information in critically ill patients. Prior studies using single indicator thermodilution have reported that 21% to 35% of patients with clinical acute respiratory distress syndrome (ARDS) have normal EVLW (<10 mL/kg). Given that lung size is independent of actual body weight, we sought to determine whether indexing EVLW to predicted or adjusted body weight affects the frequency of increased EVLW in patients with ARDS. Prospective, observational cohort study. Medical and surgical intensive care units at two academic hospitals. Thirty patients within 72 hrs of meeting American-European Consensus Conference definition of ARDS and 14 severe sepsis patients without ARDS. None. EVLW was measured for 7 days by PiCCO transpulmonary thermodilution; 225 measurements of EVLW indexed to actual body weight (ActBW) were compared with EVLW indexed to predicted body weight (PBW) and adjusted body weight (AdjBW). Mean EVLW indexed to ActBW was 12.7 mg/kg for ARDS patients and 7.8 mg/kg for non-ARDS sepsis patients (p < .0001). In all patients, EVLW increased an average of 1.1 +/- 2.1 mL/kg when indexed to AdjBW and 2.0 +/- 4.1 mL/kg when indexed to PBW. Indexing EVLW to PBW or AdjBW increased the proportion of ARDS patients with elevated EVLW (each p < .05) without increasing the frequency of elevated EVLW in non-ARDS patients. EVLW indexed to PBW had a stronger correlation to Lung Injury Score (r2 = .39 vs. r2 = .17) and PaO2/FiO2 ratio (r2 = .25 vs. r2 = .10) than did EVLW indexed to ActBW. Indexing EVLW to PBW or AdjBW reduces the number of ARDS patients with normal EVLW and correlates better to Lung Injury Score and oxygenation than using ActBW. Studies are needed to confirm the presumed superiority of this method for diagnosing ARDS and to determine the clinical treatment implications.