Machine Learning-Based Prediction of Malnutrition in Surgical In-Patients: A Validation Pilot Study.

BACKGROUND: Malnutrition in hospitalised patients can lead to serious complications, worse patient outcomes and longer hospital stays. State-of-the-art screening methods rely on scores, which need additional manual assessments causing higher workload. OBJECTIVES: The aim of this prospective study was to validate a machine learning (ML)-based approach for an automated prediction of malnutrition in hospitalised patients. METHODS: For 159 surgical in-patients, an assessment of malnutrition by dieticians was compared to the ML-based prediction conducted in the evening of admission. RESULTS: The model achieved an accuracy of 83.0% and an AUROC of 0.833 in the prospective validation cohort. CONCLUSION: The results of this pilot study indicate that an automated malnutrition screening could replace manual screening tools in hospitals.

Usefulness of the trabecular bone score in maintenance dialysis patients : A single center observational study.

BACKGROUND: The number of dialysis patients is steadily increasing. Associated comorbidities include impaired bone and mineral metabolism, termed chronic kidney disease-mineral and bone disorder (CKD-MBD), leading to a high fracture risk, increased morbidity and mortality and impaired quality of life. While the bone density is assessed with dual-energy X­ray absorptiometry (DXA), the trabecular bone score (TBS) captures the image texture as a potential index of skeletal microarchitecture. The aim of this study was to evaluate the clinical relevance of DXA and TBS in dialysis patients with and without prevalent fractures. METHODS: Bone disorders were evaluated in 82 dialysis patients (37% female) at the University Hospital of Graz, Austria, by DXA including the assessment of the TBS based on a patient interview and the local routine patient database software. The patient cohort was stratified by having sustained a fragility fracture in the past or not. Descriptive statistics, t­tests for continuous variables and χ2-tests for nominal variables including results of DXA and TBS were performed to compare these groups considering the dialysis modality and duration as well as the number of kidney transplantations. RESULTS: Of the 82 patients, 32 (39%) had a positive history of fractures. There was a significant association between dialysis duration and fracture prevalence (p < 0.05) as well as musculoskeletal pain (p < 0.01). No significant correlation between DXA/TBS parameters and musculoskeletal pain could be established. The DXA scores did not correlate with fracture prevalence with the exception of DXA radius measurements; however, fracture prevalence significantly correlated inversely with TBS (p < 0.001). CONCLUSION: The use of DXA has a limited role in fracture prediction in dialysis patients; however, the TBS seems to add information as an additional tool for fracture risk estimation in this patient population.

EHR problem list clustering for improved topic-space navigation.

BACKGROUND: The amount of patient-related information within clinical information systems accumulates over time, especially in cases where patients suffer from chronic diseases with many hospitalizations and consultations. The diagnosis or problem list is an important feature of the electronic health record, which provides a dynamic account of a patient's current illness and past history. In the case of an Austrian hospital network, problem list entries are limited to fifty characters and are potentially linked to ICD-10. The requirement of producing ICD codes at each hospital stay, together with the length limitation of list items leads to highly redundant problem lists, which conflicts with the physicians' need of getting a good overview of a patient in short time. This paper investigates a method, by which problem list items can be semantically grouped, in order to allow for fast navigation through patient-related topic spaces. METHODS: We applied a minimal language-dependent preprocessing strategy and mapped problem list entries as tf-idf weighted character 3-grams into a numerical vector space. Based on this representation we used the unweighted pair group method with arithmetic mean (UPGMA) clustering algorithm with cosine distances and inferred an optimal boundary in order to form semantically consistent topic spaces, taking into consideration different levels of dimensionality reduction via latent semantic analysis (LSA). RESULTS: With the proposed clustering approach, evaluated via an intra- and inter-patient scenario in combination with a natural language pipeline, we achieved an average compression rate of 80% of the initial list items forming consistent semantic topic spaces with an F-measure greater than 0.80 in both cases. The average number of identified topics in the intra-patient case (µIntra = 78.4) was slightly lower than in the inter-patient case (µInter = 83.4). LSA-based feature space reduction had no significant positive performance impact in our investigations. CONCLUSIONS: The investigation presented here is centered on a data-driven solution to the known problem of information overload, which causes ineffective human-computer interactions at clinicians' work places. This problem is addressed by navigable disease topic spaces where related items are grouped and the topics can be more easily accessed.

EHR Text Categorization for Enhanced Patient-Based Document Navigation.

Patients with multiple disorders usually have long diagnosis lists, constitute by ICD-10 codes together with individual free-text descriptions. These text snippets are produced by overwriting standardized ICD-Code topics by the physicians at the point of care. They provide highly compact expert descriptions within a 50-character long text field frequently not assigned to a specific ICD-10 code. The high redundancy of these lists would benefit from content-based categorization within different hospital-based application scenarios. This work demonstrates how to accurately group diagnosis lists via a combination of natural language processing and hierarchical clustering with an overall F-measure value of 0.87. In addition, it compresses the initial diagnosis list up to 89%. The manuscript discusses pitfall and challenges as well as the potential of a large-scale approach for tackling this problem.

[Development of methods to evaluate nephrological screening and support measures, and lessons learned from the Styrian nephrological screening program "niere.schützen"]. / Entwicklung von Evaluationsmöglichkeiten für nephrologische Screening- und Betreuungsmaßnahmen und lessons learned aus dem nephrologischen Früherkennungs-Programm "niere.schützen" des Landes Steiermark.

Throughout the world, the incidence and prevalence of patients with chronic kidney disease have been steadily rising. In 2016, the Styrian nephrology awareness program "niere.schützen" ("Kidney Protection") was launched to early identify patients with renal insufficiency. The aim of this study was to search for existing international nephrological screening and support programs in order to identify possible evaluation parameters and concepts for niere.schützen. A search in MEDLINE® revealed five relevant international programs from four countries. These differed from one another with respect to the population to be screened, the screening method and the support measures. All the programs involved the transparent documentation of patient data, and allowed for disease monitoring, as well as the impact of specific measures on assessed parameters and variables (laboratory data, participation rates) to be determined. Depending on the data sources employed and the availability and comprehensiveness of additional documentation, three evaluation methods of different informative value were developed. The first method requires no participant labelling, while the second and third methods require the participants to be assigned to a particular program. With the third method, the documentation also needs to be conducted in line with a disease management program. Considering that the speedy implementation of the niere.schützen program is desired for political reasons, the only practical method is the first one as it does not entail patient documentation and only involves the evaluation of process parameters.

Volume regulation and renal function at high altitude across gender.

AIMS: We investigated changes in volume regulating hormones and renal function at high altitudes and across gender. METHODOLOGY: Included in this study were 28 subjects (n = 20 males; n = 8 females. ages: 19 - 65 yrs), who ascended to a height of 3440m (HA1), on the 3rd day and to 5050m (HA2), on the 14th day. Plasma and urinary creatinine and urinary osmolality as well as plasma levels of plasma renin activity (PRA), Aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP) were measured. The plasma volume loss (PVL) was estimated from plasma density and hematocrit. Glomerular filtration rate (GFR) was measured based on nocturnal (9 hour) creatinine clearance; this was compared with various methods for estimation of GFR. RESULTS: The mean 24-hour urine production increased significantly in both sexes across the expedition. But PVL reached significance only in males. No changes in Na+ in plasma, urine or its fractional excretion were seen at both altitudes. Urinary osmolality decreased upon ascent to the higher altitudes. ADH and PRA decreased significantly at both altitudes in males but only at HA2 in females. However, no changes in aldosterone were seen across the sexes and at different altitudes. ANP increased significantly only in males during the expedition. GFR, derived from 9-h creatinine clearance (CreaCl), decreased in both sexes at HA1 but remained stable at HA2. Conventional Crea[p]-based GFR estimates (eGFR) showed only poor correlation to CreaCl. CONCLUSIONS: We report details of changes in hormonal patterns across high altitude sojourn. To our knowledge we are not aware of any study that has examined these hormones in same subjects and across gender during high altitude sojourn. Our results also suggest that depending on the estimation formula used, eGFR underestimated the observed decrease in renal function measured by CreaCl, thus opening the debate regarding the use of estimated glomerular filtration rates at high altitudes.

On-line dialysate infusion to estimate absolute blood volume in dialysis patients.

It was the aim to measure the distribution volume and the elimination of ultra-pure dialysate in stable hemodialysis patients during on-line hemodiafiltration (HDF). Dialysate was automatically infused as a volume indicator using standard on-line HDF equipment. Indicator concentration was noninvasively measured in the arterial blood-line (using the blood volume monitor, Fresenius Medical Care, Bad Homburg vor der Höhe, Germany), and its time course was analyzed to obtain the elimination rate and the distribution volume V(t) at the time of dilution. Blood volume at treatment start (V0) was calculated accounting for the degree of intradialytic hemoconcentration. Five patients (two females) were studied during 15 treatments. Two to six measurements using indicator volumes ranging from 60 to 210 ml were done in each treatment. V0 was 4.59 ± 1.15 L and larger than the volume of 4.08 ± 0.48 L estimated from anthropometric relationships. The mean half-life of infused volume was 17.2 ± 29.7 min. Given predialysis volume expansion V0 was consistent with blood volume determined from anthropometric measurements. Information on blood volume could substantially improve volume management in hemodialysis patients and fluid therapy in intensive care patients undergoing extracorporeal blood treatment. The system has the potential for complete automation using proper control inputs for BVM and HDF modules of the dialysis machine.

Absolute blood volume and hepatosplanchnic blood flow measured by indocyanine green kinetics during hemodialysis.

A technique to measure absolute blood volume and hepatosplanchnic blood flow (Q(h)) during hemodialysis (HD) is explored. The dispersion and elimination of indocyanine green (ICG) were measured using a noninvasive optical device attached to the extracorporeal system and compared with transcutaneous measurements. Distribution volume (V) and elimination rate constant (k) were determined from arterial indicator concentrations assuming standard single-pool behavior. Cardiac output (Q(c)) and access flow (Q(a)) were measured by saline dilution technique. Duplicate dilutions were available in seven subjects (two female subjects, 78.0 ± 9.66 kg dry weight). k was not different between measuring techniques (0.246 ± 0.07 vs. 0.249 ± 0.064 min⁻¹, p = n.s.). V was 4.71 ± 0.75 L (60.86 ± 10.21 ml/kg dry body weight) as anticipated for anthropometric blood volume (p = n.s). Indocyanine green half-life was 3.05 ± 0.89 min and in the range of normal liver function. Therefore, ICG clearance (K = kV, 1.14 ± 0.32 L/min) was assumed to correspond to Q(h). Systemic blood flow (Q(s)) calculated as difference between Q(c) (7.11 ± 1.47 L/min) and Q(a) (1.56 ± 0.88 L/min) was 5.55 ± 1.33 L/min. Thus, during HD 21 ± 5% of Q(s) were consumed by the hepatosplanchnic circulation. The analysis of ICG distribution and elimination using available online technology for routine HD provides plausible point-of-care information, which could be of clinical interests in extracorporeal applications.

Prevalence of detectable venous pressure drops expected with venous needle dislodgement.

Venous needle dislodgement (VND) is a potentially fatal complication during hemodialysis (HD) treatment and the venous pressure monitor is the most widely used device for its detection. VND can only be detected by the venous sensor if the resulting pressure drop exceeds the difference between the actual venous pressure and the lower alarm limit. In clinical practice, the lower alarm limit is usually set 30-40 mmHg below the actual venous pressure to avoid a disproportionate high number of nuisance alarms. The aim of this study was to quantify the number of fistulas and grafts in a group of HD patients where venous pressure monitoring can be expected to detect VND. We determined intra-access pressures in 99 chronic HD patients. Sixty-five (65.7%) had a fistula and 34 (34.3%) had a prosthetic graft as a vascular access. Mean intra-access pressure (Pa ) in fistulas was 32.6 ± 23.5 mmHg, whereas in grafts mean Pa was 60.9 ± 19.5 mmHg. Nineteen (29.2%) of the fistulas and 32 (94.1%) of the grafts exhibited an intra-access pressure above 40 mmHg. Therefore, in our study nearly all grafts but only 29% of fistulas would fulfill the requirement for venous pressure monitoring to detect VND.

Oxidative albumin damage in chronic liver failure: relation to albumin binding capacity, liver dysfunction and survival.

BACKGROUND & AIMS: Impaired binding function of albumin has been demonstrated in end-stage liver disease. This and other functional disturbances of albumin may be related to oxidative stress which is believed to play an important role in the pathogenesis of liver failure as well as sepsis. The aim of the present study was to relate oxidative modification of albumin to loss of albumin binding function in advanced chronic liver failure and in sepsis. METHODS: Patients with decompensated cirrhosis or sepsis and healthy controls were investigated. Three fractions of albumin were separated by chromatography according to the redox state of cysteine-34: non-oxidized human mercaptalbumin, reversibly oxidized human non-mercaptalbumin-1, and irreversibly oxidized human non-mercaptalbumin-2 (HNA2). Binding properties of albumin site II were measured using dansylsarcosine as a ligand. RESULTS: Both in cirrhotic and septic patients, fractions of oxidized albumin were increased and binding capacity for dansylsarcosine was decreased. Mass spectroscopy confirmed specific oxidation of cysteine-34. In cirrhotic patients, dansylsarcosine binding correlated strongly with liver function parameters and moderately with HNA2. Baseline levels of HNA2 accurately predicted 30-day and 90-day survival in cirrhotic patients and this was confirmed in an external validation cohort. CONCLUSIONS: Our results suggest that oxidative damage impairs binding properties of albumin. In advanced liver disease, reduced binding capacity of albumin site II is mainly related to impaired liver function. The plasma level of HNA2 is closely related to survival and may represent a novel biomarker for liver failure.

A challenging case of hypocalcemia supporting the concept that 25-hydroxyvitamin D status is important for intestinal calcium absorption.

CONTEXT: Intestinal mucosa seems to be responsive not only to circulating calcitriol but also to serum 25-hydroxyvitamin D concentrations. OBJECTIVE: We report a complex patient with chronic kidney disease who presented with symptomatic hypocalcemia (ionized calcium, 0.77 mmol/liter) despite regular calcitriol and calcium supplementation. METHODS: Case history, laboratory evaluation, and bone biopsies are discussed. RESULTS: Only vigorous treatment with im cholecalciferol led to a significant improvement of serum calcium, a decrease in PTH levels, and histological improvement of osteomalacic bone disease. However, oral anticoagulation became necessary for advanced peripheral artery disease, which precluded further im injections. Therefore, UVB phototherapy was initiated to treat vitamin D deficiency. CONCLUSION: This case is clinically relevant because it demonstrates that efficient calcium absorption is markedly reduced in profound vitamin D deficiency, even with normal active vitamin D levels. An important consequence is to stay aware of vitamin D deficiency in patients with compromised kidney function irrespective of regular calcitriol replacement. Second, when both parenteral and oral vitamin D administration are contraindicated, ineffective, or unavailable, UVB phototherapy is an effective option to treat vitamin D deficiency. Third, this case underlines the importance of obtaining regular 25-hydroxyvitamin D levels in complex clinical cases when prediction of individual response is unreliable.

Relationship between kinetics of albumin-bound bilirubin and water-soluble urea in extracorporeal blood purification.

BACKGROUND: The purpose of the study was to examine the relationship between urea and conjugated bilirubin kinetics during extracorporeal liver support (ELS) therapy and to determine the dose of therapy for urea and conjugated bilirubin as markers for water-soluble and protein-bound solutes, respectively. METHODS: Kinetics of urea and bilirubin were described by standard two-compartment models with central clearance, constant intercompartment clearance, constant generation rate and constant volume. While the concentration of urea was assumed as equilibrated between compartments at the beginning of ELS therapy, the concentration of conjugated bilirubin between compartments was assumed to follow the partition of albumin between plasma and interstitial spaces. Treatment dose was calculated as removed solute mass and fractional solute removal. RESULTS: Seven patients were studied during 15 treatments lasting at least 6 h. Bilirubin distribution volume of 14.8 ± 5.4 L was not different from urea extracellular water volume of 15.0 ± 2.8 L. The correspondence between models was used to predict the mass of bilirubin removed based on extracellular volume obtained from urea kinetics, average data from bilirubin kinetics, as well as selected treatment and patient information. The prediction of bilirubin mass removed based on this reduced information was not different from the mass of solute removed based on complete bilirubin kinetic analysis. CONCLUSIONS: The correspondence between kinetics of urea and conjugated bilirubin can be used to identify the bilirubin distribution volume from urea kinetic analysis. This information is then useful to estimate and predict the solute removal of conjugated bilirubin in ELS.

Clearing of toxic substances: are there differences between the available liver support devices?

Toxins accumulating in liver failure split into water solved (e.g. ammonia) and albumin bound substances (e.g. bilirubin). Because the latter cannot be removed by conventional haemodialysis, special liver support systems have been developed. The majority of data concerning elimination efficiency exist for the cell-free devices Molecular Adsorbent Recirculating System (MARS) and Prometheus, as they have been commercially available in Europe since many years. Overall, Prometheus provides higher clearances for most liver toxins, especially if they are tightly albumin bound. However, for bile acids and cytokines no such differences could be found. Single pass albumin dialysis (SPAD) can be assumed to be equally effective as MARS. None of the bioartificial liver support systems being developed is on the market today and published clearance data are scarce. In general, clearance efficiency for albumin bound substances is relatively low in all systems currently available. Besides optimizing biocompatibility and selectivity, future technologies should also focus on improved detoxification efficiency of liver support devices.

More may be less: increasing extracorporeal blood flow in an axillary arterio-arterial access decreases effective clearance.

Axillary arterio-arterial graft interposition has been described as a reasonable haemodialysis access in selected patients. In a patient with this unusual access, we measured and calculated effective clearance at different extracorporeal blood flows (Q(b)). Effective clearance increased with increasing blood flow and reached a maximum at a Q(b) of ~200 mL/min but then decreased when Q(b) was increased further. As this type of access typically provides low access flow, one has to be aware that local recirculation will easily occur. Therefore, a Q(b) above access flow has to be avoided since any increase beyond that threshold reduces effective clearance.

Efficacy and safety of anticoagulation with heparin versus heparin plus epoprostenol in patients undergoing extracorporeal liver support with Prometheus.

Anticoagulation for extracorporeal liver support is delicate due to underlying coagulation disorders in patients with liver failure and to the associated elevated bleeding risk. To date, there has been no detailed report on anticoagulation issues in patients treated with Prometheus, a device based on the principle of fractionated plasma separation and adsorption. We studied 17 patients from two centers treated with Prometheus, comparing standard anticoagulation with heparin (15 treatments) and a combination of heparin and the synthetic prostacyclin epoprostenol (22 treatments). Standard coagulation tests, proteins C and S, and thrombin-antithrombin (TAT) complex were determined, and adverse events were recorded. All but two treatments could be completed as scheduled, although filter exchange due to filter clotting was required in 24% of the treatments. Three out of 17 patients developed severe bleeding complications within 24 h of treatment. There were no overt thrombotic events. Addition of epoprostenol neither reduced coagulation-related adverse events nor improved standard coagulation parameters. Protein C, but not protein S, showed a significant reduction (23 +/- 18%) after Prometheus treatments, but levels rebounded to baseline within 18 h. TAT levels--a measure for activation of coagulation--were only altered by Prometheus in patients where TAT was already elevated before treatment. In conclusion, anticoagulation of Prometheus with heparin is feasible but still associated with a relatively high frequency of filter clotting and a considerable risk of severe bleeding in this high-risk patient population. As addition of epoprostenol did not prove beneficial, other strategies, such as regional anticoagulation with citrate, should be further evaluated.

Effect of extracorporeal liver support by molecular adsorbents recirculating system and Prometheus on redox state of albumin in acute-on-chronic liver failure.

Oxidative stress is believed to play an important role in acute-on-chronic liver failure (AoCLF). Albumin, an important transport vehicle, was found to be severely oxidized in AoCLF patients. Extracorporeal liver support systems may exert beneficial effects in AoCLF via removal of albumin-bound toxins. At present, two systems are commercially available, the molecular adsorbents recirculating system (MARS) and fractionated plasma separation, adsorption and dialysis (FPAD, also known as Prometheus). The aim of this study was to compare the effect of MARS and Prometheus treatments on the redox state of human serum albumin. Eight patients with AoCLF underwent alternating treatments with either MARS or Prometheus in a randomized cross-over design. Sixteen treatments (eight MARS and eight Prometheus) were available for analysis. The fraction of human mercaptalbumin (HMA), human nonmercaptalbumin-1 (HNA1), and human nonmercaptalbumin-2 (HNA2) were measured before and after single MARS and Prometheus treatments and during follow-up. In AoCLF patients the oxidized fractions of albumin, HNA1, and HNA2 were markedly increased. Both MARS and Prometheus treatments resulted in a shift of HNA1 to HMA, while HNA2 was not significantly affected. This shift in albumin fractions was transient and disappeared within 24 h after treatment. There were no significant differences between MARS and Prometheus treatments with respect to the redox state of albumin. Both MARS and Prometheus treatments lead to transient improvements of the redox state of albumin, which could be beneficial in the treatment of AoCLF.