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Seasonal human influenza viruses continually change antigenically to escape from neutralizing antibodies. It remains unclear how genetic variation in the intrahost virus population and selection at the level of individual hosts translates to the fast-paced evolution observed at the global level because emerging intrahost antigenic variants are rarely detected. We tracked intrahost variants in the hemagglutinin and neuraminidase surface proteins using longitudinally collected samples from 52 patients infected by A/H3N2 influenza virus, mostly young children, who received oseltamivir treatment. We identified emerging putative antigenic variants and oseltamivir-resistant variants, most of which remained detectable in samples collected at subsequent days, and identified variants that emerged intrahost immediately prior to increases in global rates. In contrast to most putative antigenic variants, oseltamivir-resistant variants rapidly increased to high frequencies in the virus population. Importantly, the majority of putative antigenic variants and oseltamivir-resistant variants were first detectable four or more days after onset of symptoms or start of treatment, respectively. Our observations demonstrate that de novo variants emerge, and may be positively selected, during the course of infection. Additionally, based on the 4–7 days post-treatment delay in emergence of oseltamivir-resistant variants in six out of the eight individuals with such variants, we find that limiting sample collection for routine surveillance and diagnostic testing to early timepoints after onset of symptoms can potentially preclude detection of emerging, positively selected variants.

Item does not contain fulltext OBJECTIVE: Randomized trials have shown an initial survival benefit of endovascular over conventional open abdominal aortic aneurysm repair but no long-term difference up to 6 years after repair. Longer follow-up may be required to demonstrate the cumulative negative impact on survival of higher reintervention rates associated with endovascular repair. METHODS: We updated the results of the Dutch Randomized Endovascular Aneurysm Management (DREAM) trial, a multicenter, randomized controlled trial comparing open with endovascular aneurysm repair, up to 15 years of follow-up. Survival and reinterventions were analyzed on an intention-to-treat basis. Causes of death and secondary interventions were compared by use of an events per person-year analysis. RESULTS: There were 178 patients randomized to open and 173 to endovascular repair. Twelve years after randomization, the cumulative overall survival rates were 42.2% for open and 38.5% for endovascular repair, for a difference of 3.7 percentage points (95% confidence interval, -6.7 to 14.1; P = .48). The cumulative rates of freedom from reintervention were 78.9% for open repair and 62.2% for endovascular repair, for a difference of 16.7 percentage points (95% confidence interval, 5.8-27.6; P = .01). No differences were observed in causes of death. Cardiovascular and malignant disease account for the majority of deaths after prolonged follow-up. CONCLUSIONS: During 12 years of follow-up, there was no survival difference between patients who underwent open or endovascular abdominal aortic aneurysm repair, despite a continuously increasing number of reinterventions in the endovascular repair group. Endograft durability and the need for continued endograft surveillance remain key issues.

Implant-related irritation is a technique-specific complication seen in a substantial number of patients treated with intramedullary nailing for clavicle fractures. The purpose of this study was to identify predictors for developing implant-related irritation in patients with displaced midshaft clavicle fractures treated with elastic stable intramedullary nailing. A retrospective analysis of the surgical database in two level 2 trauma centers was performed. Patients who underwent intramedullary nailing for displaced midshaft clavicle fractures between 2005 and 2012 in the first hospital were included. Age, gender, fracture comminution and fracture location were assessed as possible predictors for developing irritation using multivariate logistic regression analysis. These predictors were externally validated using data of patients treated in another hospital. Eighty-one patients were included in initial analysis. In the multivariate analysis, comminuted fractures in comparison to non-comminuted fractures (72 vs. 38%, p = 0.027) and fracture location (p

Contains fulltext : 215386.pdf (Publisher’s version ) (Open Access) BACKGROUND: Autoimmune hepatitis requires long-term therapy, and systemic corticosteroids are the backbone of therapeutic management. Prolonged use of corticosteroids may lead to adverse events but data from long-term studies are mainly derived from studies in rheumatic diseases. AIM: To assess cataract, diabetes and fractures in relation to corticosteroid doses in the long-term maintenance treatment of patients with autoimmune hepatitis. METHODS: We retrospectively collected data on 476 patients (77% women) with an established diagnosis of autoimmune hepatitis. Binary logistic regression with a generalised estimating equation was used to analyse the association between current corticosteroid use and the incidence of cataract, diabetes and fractures with onset after autoimmune hepatitis diagnosis. We corrected for sex, age, cirrhosis at diagnosis and predniso(lo)ne use in the prior 3 years to account for possible ongoing effects. RESULTS: A total of 6634 years, with a median of 13 (range 1-40) per patient were recorded. The median age at diagnosis was 44 years (range 2-88). Adverse events were documented in 120 (25%) patients. Low-dose predniso(lo)ne (0.1-5.0 mg/d) increased the odds of fractures whereas higher doses (>5.0 mg/d) increased the odds of cataracts and diabetes. Budesonide increased the odds of cataract and fractures; this effect was independent of predniso(lo)ne use in the prior 1, 2 or 3 years. CONCLUSIONS: Even low doses of corticosteroids frequently lead to substantial adverse events refuting the assumption that adverse events are prevented by administering low doses.

Introduction & Aims: Small studies have found that black patients with autoimmune hepatitis (AIH) present with more aggressive disease. We aimed to characterize the presentation and outcome in black and white patients with AIH. Methods: We performed a retrospective study, collecting information from databases of patients with AIH attending the Institute of Liver studies at King's College Hospital, London (1971–October 2015, the Royal Free Hospital, London (1982 through December 2016) and the multicenter Dutch Autoimmune Hepatitis Study Group cohort (2006–August 2016). We identified 88 black patients with AIH and we compared their clinical characteristics and outcomes to 897 white patients with AIH. Results: Black patients presented at a younger age (median 38 years vs 45 years) (P =.007), had higher IgG levels (mean 31.0 mg/dL vs 27.5 mg/dL) (P =.04), but there were no significant differences between groups in auto-antibody profiles, International AIH Group scores, or sex distribution of disease. A higher proportion of black patients had systemic lupus erythematosus (10%) than white patients (2%) (P ≤.001). There was no significant difference in proportions of patients with a response to standard therapy (86% for black patients vs 91% for white patients; P =.20) or in rate of relapse (57% vs 50%; P =.3). Despite this, black patients had an increased risk of liver transplantation and liver-related death (hazard ratio 2.4, 95% confidence interval, 1.4–4.0; P

Contains fulltext : 208770.pdf (Publisher’s version ) (Open Access) OBJECTIVE: To establish a hospital-based surveillance network with national coverage for antimicrobial resistance (AMR) and antibiotic consumption in Viet Nam. METHODS: A 16-hospital network (Viet Nam Resistance: VINARES) was established and consisted of national and provincial-level hospitals across the country. Antimicrobial susceptibility testing results from routine clinical diagnostic specimens and antibiotic consumption data in Defined Daily Dose per 1000 bed days (DDD/1000 patient-days) were prospectively collected and analysed between October 2012 and September 2013. RESULTS: Data from a total of 24 732 de-duplicated clinical isolates were reported. The most common bacteria were: Escherichia coli (4437 isolates, 18%), Klebsiella spp. (3290 isolates, 13%) and Acinetobacter spp. (2895 isolates, 12%). The hospital average antibiotic consumption was 918 DDD/1000 patient-days. Third-generation cephalosporins were the most frequently used antibiotic class (223 DDD/1000 patient-days, 24%), followed by fluoroquinolones (151 DDD/1000 patient-days, 16%) and second-generation cephalosporins (112 DDD/1000 patient-days, 12%). Proportions of antibiotic resistance were high: 1098/1580 (69%) Staphylococcus aureus isolates were methicillin-resistant (MRSA); 115/344 isolates (33%) and 90/358 (25%) Streptococcus pneumoniae had reduced susceptibility to penicillin and ceftriaxone, respectively. A total of 180/2977 (6%) E. coli and 242/1526 (16%) Klebsiella pneumoniae were resistant to imipenem, respectively; 602/1826 (33%) Pseudomonas aeruginosa were resistant to ceftazidime and 578/1765 (33%) to imipenem. Of Acinetobacter spp. 1495/2138 (70%) were resistant to carbapenems and 2/333 (1%) to colistin. CONCLUSIONS: These data are valuable in providing a baseline for AMR among common bacterial pathogens in Vietnamese hospitals and to assess the impact of interventions. 01 september 2019

Background Pruritus (itch) is a frequent, burdensome and difficult-to-treat symptom in patients with cholestasis. Fibrates are currently under investigation for the treatment of primary biliary cholangitis in patients with a suboptimal response to ursodeoxycholic acid. Moreover, there is empirical evidence for a possible antipruritic effect. We aim to prove this in a randomized controlled trial, including patients with cholestatic liver diseases other than primary biliary cholangitis that are accompanied by pruritus. Methods A multicenter investigator-initiated, double-blind, randomized placebo-controlled trial to evaluate the effect of bezafibrate on cholestatic pruritus in 84 adult patients with primary biliary cholangitis or primary/secondary sclerosing cholangitis. Primary outcome is the proportion of patients with a reduction of itch intensity of 50% or more (measured on a Visual Analog Scale) after 21 days of treatment with bezafibrate 400 mg qid or placebo. Secondary outcomes include the effect of bezafibrate on a five-dimensional itch score, liver disease-specific quality of life, serum liver tests and autotaxin activity. Safety will be evaluated through serum parameters for kidney function and rhabdomyolysis as well as precise recording of (serious) adverse events. We provide a schematic overview of the study protocol and describe the methods used to recruit and randomize patients, collect and handle data and perform statistical analyses. Discussion Given its favorable safety profile and anticholestatic properties, bezafibrate may become the new first-line treatment option for treating cholestatic pruritus. Trial registration Netherlands Trial Register, ID: NCT02701166. Registered on 2 March 2016; Netherlands Trial Register, ID: NTR5436. Registered on 3 August 2015. Electronic supplementary material The online version of this article (doi:10.1186/s13063-017-1966-8) contains supplementary material, which is available to authorized users.

Autoimmune pancreatitis (AIP) is often difficult to distinguish from pancreatic carcinoma or other pancreatobiliary diseases. High serum levels of carbohydrate antigen 19-9 (Ca 19-9) are indicative of malignancies, whereas high levels of immunoglobulin (Ig)G4 (> 1.4 g/l) are characteristic of AIP. We investigated whether serum levels of these proteins can differentiate between these diseases. We measured levels of Ca 19-9 and IgG4 in serum samples from 33 patients with AIP, 53 with pancreatic carcinoma, and 145 with other pancreatobiliary disorders. We determined cut-off levels for each assay. Logistic regression analysis was used to evaluate combined data on Ca 19-9, IgG4, and bilirubin levels. Low levels of Ca 19-9 were independently associated with AIP, compared with pancreatic adenocarcinoma [odds ratio (OR) 0.28; 95 % confidence interval (CI) 0.13-0.59; p = 0.0001]. Using an upper level of 74 U/ml, the assay for Ca 19-9 identified patients with AIP with 73 % sensitivity and 74 % specificity. Using a lower level of 2.6 g/l, the assay for IgG4 identified these patients with 70 % sensitivity and 100 % specificity. Combining data, levels of Ca 19-9 < 74 U/ml and IgG4 > 1.0 g/l identified patients with AIP with 94 % sensitivity and 100 % specificity. Patients with AIP have lower levels of Ca 19-9 than those patients with pancreatic carcinoma. Measurement of either the Ca 19-9 or the IgG4 level alone are not accurate enough for diagnosis. However, the combination of Ca 19-9 < 74 U/ml and IgG4 > 1.0 g/l distinguishes patients with AIP from those patients with pancreatic carcinoma with 94 % sensitivity and 100 % specificity.

Item does not contain fulltext Abstract Background and aims. Epidemiological data on autoimmune hepatitis (AIH) are scarce. In this study, we determined the clinical and epidemiological characteristics of AIH patients in the Netherlands (16.7 million inhabitants). Methods. Clinical characteristics were collected from 1313 AIH patients (78% females) from 31 centers, including all eight academic centers in the Netherlands. Additional data on ethnicity, family history and symptoms were obtained by the use of a questionnaire. Results. The prevalence of AIH was 18.3 (95% confidential interval [CI]: 17.3-19.4) per 100,000 with an annual incidence of 1.1 (95% CI: 0.5-2) in adults. An incidence peak was found in middle-aged women. At diagnosis, 56% of patients had fibrosis and 12% cirrhosis in liver biopsy. Overall, 1% of patients developed HCC and 3% of patients underwent liver transplantation. Overlap with primary biliary cirrhosis and primary sclerosing cholangitis was found in 9% and 6%, respectively. The clinical course did not differ between Caucasian and non-Caucasian patients. Other autoimmune diseases were found in 26% of patients. Half of the patients reported persistent AIH-related symptoms despite treatment with a median treatment period of 8 years (range 1-44 years). Familial occurrence was reported in three cases. Conclusion. This is the largest epidemiological study of AIH in a geographically defined region and demonstrates that the prevalence of AIH in the Netherlands is uncommon. Although familial occurrence of AIH is extremely rare, our twin data may point towards a genetic predisposition. The high percentage of patients with cirrhosis or fibrosis at diagnosis urges the need of more awareness for AIH.

The use of self-expandable metal stents (SEMS) has occasionally been described for the treatment of uncontrollable esophageal variceal bleeding (EVB) as a bridge to an alternative treatment option (i. e. transjugular intrahepatic portosystemic shunt [TIPS]). It is currently not known whether SEMS placement is appropriate for more than temporary hemostasis. This case series report describes five patients in whom EVB could not be controlled with variceal band ligation and who were not suitable to undergo a TIPS procedure at the time of bleeding. SEMS were placed in these patients with the intent of definitive treatment. Successful initial hemostasis was achieved in all five patients, and sustained hemostasis occurred in four. Stents were removed from two patients after > 14 days and remained in situ until death in three other patients (range 6 - 214 days). No complications related to this longer duration were observed. In one case, TIPS could be performed at a later stage. SEMS could be a definitive treatment for uncontrollable esophageal bleeding in patients with a limited life expectancy or those unsuitable for TIPS at the time of bleeding.

Contains fulltext : 170312.pdf (Publisher’s version ) (Open Access) Acinetobacter baumannii is an important cause of multidrug-resistant hospital acquired infections in the world. Here, we investigate the presence of NDM-1 and other carbapenemases among carbapenem-resistant A. baumannii isolated between August 2010 and December 2014 from three large hospitals in Hanoi, Vietnam. We identified 23/582 isolates (4 %) (11 from hospital A, five from hospital B, and seven from hospital C) that were NDM-1 positive, and among them 18 carried additional carbapenemase genes, including seven isolates carrying NDM-1, IMP-1, and OXA-58 with high MICs for carbapenems. Genotyping indicated that NDM-1 carrying A. baumannii have expanded clonally in these hospitals. Five new STs (ST1135, ST1136, ST1137, ST1138, and ST1139) were identified. One isolate carried NDM-1 on a plasmid belonging to the N-repA replicon type; no NDM-1-positive plasmids were identified in the other isolates. We have shown the extent of the carbapenem resistance and the local clonal spread of A. baumannii carrying NDM-1 in these hospitals; coexistence of NDM-1 and IMP-1 is reported for the first time from Vietnam here, and this will further seriously limit future therapeutic options.

Item does not contain fulltext Extensive population-based studies are much needed to accurately establish epidemiology and disease course in patients with primary sclerosing cholangitis (PSC). We aimed to obtain population-based prevalence and incidence figures, insight in disease course with regard to survival, liver transplantation (LT), and occurrence of malignancies, as well as risk factors thereof. Four independent hospital databases were searched in 44 hospitals in a large geographically defined area of the Netherlands, comprising 50% of the population. In addition, all PSC patients in the three Dutch liver transplant centers and all inflammatory bowel disease (IBD) patients in the adherence area of a large district hospital were identified. All medical records were reviewed on-site, verifying diagnosis. Five hundred and ninety PSC patients were identified, resulting in an incidence of 0.5 and a point prevalence of 6.0 per 100,000. Median follow up was 92 months. Estimated median survival from diagnosis until LT or PSC-related death in the entire cohort was 21.3 years, as opposed to 13.2 years in the combined transplant centers cohort (n = 422; P < 0.0001). Colorectal carcinoma (CRC) risk was 10-fold increased, as compared to ulcerative colitis controls, and developed at a much younger age (39 years; range, 26-64), compared to IBD controls (59 years; range, 34-73; P = 0.019). Colonoscopic surveillance was associated with significantly better outcome. Conclusion: This study exemplifies that, for relatively rare diseases, it is paramount to collect observational data from large, population-based cohorts, because incidence and prevalence rates of PSC are markedly lower and survival much longer than previously reported. The selection of a bias-free, population-based cohort showed a significantly longer survival, compared to the tertiary referral cohort. CRC can develop at an early age, warranting surveillance from time of PSC diagnosis. (Hepatology 2013; 58:2045-2055).

Background: Identifying patients at risk for aneurysm rupture and sac expansion after open and endovascular abdominal aortic aneurysm (AAA) repair (EVAR) may help to attenuate this risk by intensifying follow-up and early detection of problems. The goal of this study was to validate the St George’s Vascular Institute (SGVI) score to identify patients at risk for a secondary intervention after elective aneurysm repair. Methods: A post hoc on-treatment analysis of a randomized trial comparing open AAA repair and EVAR was performed. In this multicenter trial, 351 patients were randomly assigned to undergo open AAA repair or EVAR. Information on survival and reinterventions was available for all patients at 5 years postoperatively, for 79% at 6 years, and for 53% at 7 years. Open repair was completed in 173 patients and EVAR in 171, based on an on-treatment analysis. Because 17 patients had incomplete anatomic data, 327 patients (157 open repair and 170 EVAR) were available for analysis. During 6 years of follow-up, 78 patients underwent at least one reintervention. The SGVI score, which is calculated from preoperative AAA morphology using aneurysm and iliac diameter, predictively dichotomized patients into groups at highrisk or low-risk for a secondary intervention. The observed freedom from reintervention was compared between groups at predicted high-risk and predicted low-risk. Results: The 20 patients in the high-risk group were indeed at higher risk for a secondary intervention compared with the 307 patients predicted to be at low risk (hazard ratio [HR], 3.82; 95% confidence interval [CI], 2.05-7.11; P < .001). Discrimination between high-risk and low-risk groups was valid for EVAR (HR, 4.06; 95% CI, 1.93-8.51; P < .001) and for open repair (HR, 3.41; 95% CI, 1.02-11.4; P [ .033). Conclusions: The SGVI score appears to be a useful tool to predict reintervention risk in patients after open repair and EVAR.

Occasionally patients undergoing resection for presumed malignancy of the pancreatic head are diagnosed postoperatively with benign disease. Autoimmune pancreatitis (AIP) is a rare disease that mimics pancreatic cancer. We aimed to determine the prevalence of benign disease and AIP in patients who underwent pancreatoduodenectomy (PD) over a 9-year period, and to explore if and how surgery could have been avoided.All patients undergoing PD between 2000 and 2009 in a tertiary referral centre were analyzed retrospectively. In cancer-negative cases, postoperative diagnosis was reassessed. Preoperative index of suspicion of malignancy was scored as non-specific, suggestive, or high. In AIP patients, diagnostic criteria systems were checked.A total of 274 PDs were performed for presumed malignancy. The prevalence of benign disease was 8.4 %, overall prevalence of AIP was 2.6 %. Based on preoperative index of suspicion of malignancy, surgery could have been avoided in 3 non-AIP patients. All AIP patients had sufficient index to justify surgery. If diagnostic criteria would have been checked; however, surgery could have been avoided in one to five AIP patients.The prevalence of benign disease in patients who underwent PD for presumed malignancy was 8.4 %, nearly one-third attributable to AIP. Although misdiagnosis of AIP as carcinoma is a problem of limited quantitative importance, every effort to establish the correct diagnosis should be undertaken considering the major therapeutic consequences. IgG4 measurement and systematic use of diagnostic criteria systems are recommended for every candidate patient for PD when there is no histological proof of malignancy.

Background Treatment failure occurs in 20% of autoimmune hepatitis patients on prednisolone and azathioprine (AZA). There is no established second line treatment. Aim To assess the efficacy of mycophenolate mofetil as second line treatment after AZA-intolerance or AZA-nonresponse in autoimmune hepatitis and overlap syndromes. Methods Consecutive patients from the Dutch Autoimmune Hepatitis Group cohort, consisting of 661 patients, with autoimmune hepatitis or overlap syndromes, AZA-intolerance or AZA-nonresponse and past or present use of mycophenolate mofetil were included. Primary endpoint of mycophenolate mofetil treatment was biochemical remission. Secondary endpoints were biochemical response (without remission), treatment failure and prevention of disease progression. Results Forty-five patients treated with mycophenolate mofetil were included. In autoimmune hepatitis remission or response was achieved in 13% and 27% in the AZA-nonresponse group compared to 67% and 0% in the AZA-intolerance group (P = 0.008). In overlap-syndromes remission or response was reached in 57% and 14% in the AZA-nonresponse group and 63% and 25% of the AZA-intolerance group (N.S.); 33% had side effects and 13% discontinued mycophenolate mofetil. Overall 38% had treatment failure; this was 60% in the autoimmune hepatitis AZA-nonresponse group. Decompensated liver cirrhosis, liver transplantations and death were only seen in the autoimmune hepatitis AZA-nonresponse group (P < 0.001). Conclusions Mycophenolate mofetil induced response or remission in a majority of patients with autoimmune hepatitis and azathioprine-intolerance and with overlap syndromes, irrespective of intolerance or nonresponse for azathioprine. In autoimmune hepatitis with azathioprine nonresponse mycophenolate mofetil is less often effective.

Background and aims: Ursodeoxycholic acid (UDCA) has an established effect on liver bio-chemistries in primary biliary cirrhosis (PBC). Few studies have evaluated long-term laboratory treatment effects and data beyond 6 years are not available. The aim of this study was to assess the long-term evolution of liver biochemistries during prolonged treatment with UDCA in biochemically non-advanced PBC. Patients and methods: Prospective multicenter cohort study of patients with PBC with pretreatment normal bilirubin and albumin, treated with UDCA 13-15 mg/kg/day. At yearly intervals, follow-up data including serum bilirubin, alkaline phosphatase (ALP), transaminases, albumin and IgM were collected. Data were analyzed with a repeated measurement model. Results: Two hundred and twenty-five patients were included and followed during a median period of 10.3 years. Following 1-year treatment with UDCA 36-100% of the total biochemical improvement was achieved, the maximum response was observed after 3 years. After initial improvements, bilirubin and AST levels increased and albumin levels significantly decreased after 6-10 years. However, these changes were of limited magnitude. The beneficial effects on ALT and ALP were maintained while IgM continued to decrease. Conclusion: In non-advanced PBC the biochemical response to UDCA is maintained up to 15 years. The long-term evolution of bilirubin, albumin and ALT differs from that of ALP and AST. The mean IgM level normalised and levels continued to decrease during the period of follow-up. (C) 2010 Elsevier Masson SAS. All rights reserved.

Autoimmune pancreatitis (AIP) is associated with a marked elevation of serum total IgG₄ . Although there is evidence of autoimmunity in AIP, there are also signs of an allergic nature of its pathogenesis. Therefore, we determined both IgE and IgG₄ in 13 patients with AIP, in 12 patients with pancreatic carcinoma and in 14 patients with atopic allergy and investigated the relationship between IgE and IgG₄ . Total IgG₄ was determined by automated nephelometry and total IgE by automated enzyme fluoroimmunoassay. Both total IgE and total IgG₄ levels in patients with AIP were significantly higher than those in patients with pancreatic carcinoma (P = 0.0004 and P = 0.015, respectively). There was a significant correlation between the total IgE and total IgG₄ levels in patients with AIP and patients with atopic allergy (r(s) =0.82, P=0.0006 and r(s) =0.88, P < 0.0001, respectively). The IgE/ IgG₄ ratio in sera from patients with atopic allergy was significantly different (P = 0.0012) from this ratio in sera from patients with AIP. These results suggest that analysis of total IgE in serum might be useful in the differentiation between autoimmune pancreatitis and pancreatic carcinoma.

This study was performed to assess the value of electrical impedance tomography (EIT) as an indicator of tidal (V(T)) and end expiratory lung volume (EELV).EIT measurements were performed in seven healthy piglets during constant tidal volume ventilation at incremental and decremental positive end-expiratory pressure (PEEP) levels. Tidal impedance changes were calibrated to volume using V(T) calculated from flow at the airway opening. Simultaneously, calibrated respiratory inductive plethysmography was used to measure EELV changes, and used as a reference standard.EIT systematically underestimated both V(T) and EELV changes when EELV deviated from the level at which it was calibrated. Calculated over the entire pressure-volume curve, EIT systematically underestimated V(T) by 28 ml, with a precision from -16 to 72 ml. EELV was systemically underestimated by 406 ml, with a precision of -38 to 849 ml. Nonlinear recruitment in the ventral regions of the lungs was the main cause of this underestimation.Tidal and end-expiratory changes in pulmonary impedance reflect corresponding changes in lung volume, but the increasing underestimation with increasing lung volume should be taken into account in the analysis of EIT data.