265 Incidence, determinants and prognostic relevance of HS-troponin and natriuretic peptides elevation at admission in hospitalized COVID-19 pneumonia patients

Aims

myocardial involvement in the course of Coronavirus disease 2019 (COVID-19) pneumonia has been reported, though not fully characterized yet. Aim of the present study is to undertake a joint evaluation of hs-Troponin and natriuretic peptides (NP) in patients hospitalized for COVID-19 pneumonia.

Methods and results

in this multicenter observational study, we analyzed data from n = 111 COVID-19 patients admitted to dedicated "COVID-19" medical units. Hs-Troponin was assessed in n = 103 patients and NP in n = 82 patients on admission; subgroups were identified according to values beyond reference range. increased hs-Troponin and NP were found in 38% and 56% of the cases respectively. As compared to those with normal cardiac biomarkers, these patients were older, had higher prevalence of cardiovascular diseases (CVD) and more severe COVID-19 pneumonia by higher CRP and D-dimer and lower PaO2/FIO2. Two-dimensional echocardiography performed in a subset of patients (n = 24) showed significantly reduced left ventricular ejection fraction in patients with elevated NP only (p = 0.02), whereas right ventricular systolic function (tricuspid annular plane systolic excursion) was significantly reduced both in patients with high hs-Troponin and NP (p = 0.022 and p = 0.03 respectively). On multivariable analysis, independent associations were found of hs-Troponin with age, PaO2/FIO2 and D-dimer (B = 0.419, p = 0.001; B=-0.212, p = 0.013 and B = 0.179, p = 0.037 respectively), and of NP with age and previous CVD (B = 0.480, p < 0.001 and B = 0.253, p = 0.001 respectively). In patients with in-hospital mortality (n = 23, 21%) hs-Troponin and NP were both higher (p = 0.001 and p = 0.002 respectively), while increasing hs-troponin and NP were associated with worse in-hospital prognosis [OR 4.88 (95% CI 1.9-12.2), p = 0.001 (adjusted OR 3.1 (95% CI 1.2-8.5), p = 0.025) and OR 4.67 (95% CI 2-10.8), p < 0.001 (adjusted OR 2.89 (95% CI 1.1-7.9), p = 0.04) respectively]. Receiver operator characteristic curves showed good ability of hs-Troponin and NP in predicting in-hospital mortality (AUC = 0.869 p < 0.001 and AUC = 0.810, p < 0.001 respectively).

Conclusion

myocardial involvement at admission is common in COVID-19 pneumonia and associated to worse prognosis, suggesting a role for cardiac biomarkers assessment in COVID-19 risk stratification. Independent associations of hs-Troponin with markers of disease severity and of NP with underlying CVD might point towards existing different mechanisms leading to their elevation in this setting.

Incidence and determinants of high-sensitivity troponin and natriuretic peptides elevation at admission in hospitalized COVID-19 pneumonia patients

BACKGROUND

Myocardial involvement in the course of coronavirus disease 2019 (COVID-19) pneumonia has been reported, though not fully characterized yet. The aim of the present study is to undertake a joint evaluation of hs-Troponin and natriuretic peptides (NP) in patients hospitalized for COVID-19 pneumonia.

METHODS

In this multicenter observational study, we analyzed data from n = 111 patients. Cardiac biomarkers subgroups were identified according to values beyond reference range.

RESULTS

Increased hs-Troponin and NP were found in 38 and 56% of the cases, respectively. As compared to those with normal cardiac biomarkers, these patients were older, had higher prevalence of cardiovascular diseases (CVD) and had more severe COVID-19 pneumonia by higher CRP and D-dimer and lower PaO2/FIO2. Two-dimensional echocardiography performed in a subset of patients (n = 24) showed significantly reduced left ventricular ejection fraction in patients with elevated NP (p = 0.02), whereas right ventricular systolic function (tricuspid annular plane systolic excursion) was significantly reduced both in patients with high hs-Troponin and NP (p = 0.022 and p = 0.03, respectively). Both hs-Troponin and NP were higher in patients with in-hospital mortality (p = 0.001 and p = 0.002, respectively). On multivariable analysis, independent associations were found of hs-Troponin with age, PaO2/FIO2 and D-dimer (B = 0.419, p = 0.001; B = - 0.212, p = 0.013; and B = 0.179, p = 0.037, respectively) and of NP with age and previous CVD (B = 0.480, p < 0.001; and B = 0.253, p = 0.001, respectively).

CONCLUSIONS

Myocardial involvement at admission is common in COVID-19 pneumonia. Independent associations of hs-Troponin with markers of disease severity and of NP with underlying CVD might point toward existing different mechanisms leading to their elevation in this setting.

Substrate Supporting Disc Method for Confirmed Detection of Total Coliforms and E. coli in all Foods: Collaborative Study

The Coli Complete® substrate supporting disc (SSD) method for simultaneous confirmed total coliform count and Escherichia coli determination in all foods was compared with AOAC most probable number (MPN) methods, 966.23 and 966.24. Twenty-nine laboratories participated in this collaborative study in which 6 food types were analyzed. Four food types, raw ground beef, pork sausage, raw liquid milk, and nut meats, were naturally contaminated with coliform bacteria. Two foods, dry egg and fresh frozen vegetables, were seeded with coliforms. Three food types, ground beef, raw liquid milk, and pork sausage, were naturally contaminated with E. coli. Although pork sausage was naturally contaminated, the level was very low (&lt;10/50 g); therefore, additional E. coli were inoculated into 1 lot of this food type. Three food types, nut meats, dry egg, and fresh frozen vegetables, were inoculated with E. coli. For naturally contaminated samples, duplicate determinations were made on 3 separate lots for each food type. For inoculated samples, low, medium, and high contamination levels plus uninoculated control samples were examined in duplicate. Data were analyzed separately for total coliform bacteria and for E. coli. Mean log MPN counts were determined by the SSD method and the appropriate AOAC MPN method. Results were then analyzed for repeatability, reproducibility, and mean log MPN statistical equivalence. Results were statistically equivalent for all total coliform levels in all food types except frozen vegetable and raw nut meat uninoculated control samples and 1 lot of pork sausage where the SSD method produced statistically significant greater numbers. For the E. coli determinations, results were statistically equivalent across all samples and all levels for each food type. The SSD method has been adopted first action by AOAC International for confirmed detection of total coliforms and E. coli in all foods.

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Zusammenfassung. In dieser Studie wurden die Prävalenz sowie saisonale Fluktuationen des VitD-Mangels bei Bewohnern des Tessins evaluiert. Klinische Indikatoren zur Erkennung eines VitD-Mangelzustands wurden untersucht (Alter, Geschlecht, Hauptdiagnose, Komorbiditäten, Medikamentenanzahl). Beim Eintreffen auf der Notfallstation des Regionalspitals Bellinzona wurde bei je einer Population älterer internistischer Patienten eine einmalige VitD-Serumspiegelbestimmung im Frühling (n = 58) und im Herbst (n = 49) durchgeführt. Die Prävalenz des VitD-Mangels im Frühling betrug 98 % (Serumspiegelmittelwert 21,4±12,2 nmol/l) versus 63 % im Herbst (Serumspiegelmittelwert 43,7±18,6 nmol/l). Auch nach dem Sommer litten 66 % der Patienten an einem VitD-Mangel. Es konnten keine verlässlichen Indikatoren eruiert werden. Angesichts dieser Ergebnisse und der BAG-Empfehlungen ist eine Prophylaxe mit 800 IE täglich bei allen älteren Schweizern, v.a. im Winter, sinnvoll. Diese Präventionsmassnahme ist kostengünstig, einfach, sicher und effektiv.

Precursory changes in seismic velocity for the spectrum of earthquake failure modes

Temporal changes in seismic velocity during the earthquake cycle have the potential to illuminate physical processes associated with fault weakening and connections between the range of fault slip behaviors including slow earthquakes, tremor and low frequency earthquakes1. Laboratory and theoretical studies predict changes in seismic velocity prior to earthquake failure2, however tectonic faults fail in a spectrum of modes and little is known about precursors for those modes3. Here we show that precursory changes of wave speed occur in laboratory faults for the complete spectrum of failure modes observed for tectonic faults. We systematically altered the stiffness of the loading system to reproduce the transition from slow to fast stick-slip and monitored ultrasonic wave speed during frictional sliding. We find systematic variations of elastic properties during the seismic cycle for both slow and fast earthquakes indicating similar physical mechanisms during rupture nucleation. Our data show that accelerated fault creep causes reduction of seismic velocity and elastic moduli during the preparatory phase preceding failure, which suggests that real time monitoring of active faults may be a means to detect earthquake precursors.

Laboratory observations of slow earthquakes and the spectrum of tectonic fault slip modes

Slow earthquakes represent an important conundrum in earthquake physics. While regular earthquakes are catastrophic events with rupture velocities governed by elastic wave speed, the processes that underlie slow fault slip phenomena, including recent discoveries of tremor, slow-slip and low-frequency earthquakes, are less understood. Theoretical models and sparse laboratory observations have provided insights, but the physics of slow fault rupture remain enigmatic. Here we report on laboratory observations that illuminate the mechanics of slow-slip phenomena. We show that a spectrum of slow-slip behaviours arises near the threshold between stable and unstable failure, and is governed by frictional dynamics via the interplay of fault frictional properties, effective normal stress and the elastic stiffness of the surrounding material. This generalizable frictional mechanism may act in concert with other hypothesized processes that damp dynamic ruptures, and is consistent with the broad range of geologic environments where slow earthquakes are observed.

Slow earthquakes, where fault slip is slow, can be large and may help trigger regular earthquakes, but the mechanics of slow slip are not fully understood. Leeman et al. show through laboratory experiments that slow slip behaviour on faults is controlled by the frictional dynamics of the surrounding material.

The impact of electronic health records on healthcare quality: a systematic review and meta-analysis

OBJECTIVE

To assess the impact of electronic health record (EHR) on healthcare quality, we hence carried out a systematic review and meta-analysis of published studies on this topic.

METHODS

PubMed, Web of Knowledge, Scopus and Cochrane Library databases were searched to identify studies that investigated the association between the EHR implementation and process or outcome indicators. Two reviewers screened identified citations and extracted data according to the PRISMA guidelines. Meta-analysis was performed using the random effects model for each indicator. Heterogeneity was quantified using the Cochran Q test and I2 statistics, and publication bias was assessed using the Egger's test.

RESULTS

Of the 23 398 citations identified, 47 articles were included in the analysis. Meta-analysis showed an association between EHR use and a reduced documentation time with a difference in mean of -22.4% [95% confidence interval (CI) = -38.8 to -6.0%; P < 0.007]. EHR resulted also associated with a higher guideline adherence with a risk ratio (RR) of 1.33 (95% CI = 1.01 to 1.76; P = 0.049) and a lower number of medication errors with an overall RR of 0.46 (95% CI = 0.38 to 0.55; P < 0.001), and adverse drug effects (ADEs) with an overall RR of 0.66 (95% CI = 0.44 to 0.99; P = 0.045). No association with mortality was evident (P = 0.936). High heterogeneity among the studies was evident. Publication bias was not evident.

CONCLUSIONS

EHR system, when properly implemented, can improve the quality of healthcare, increasing time efficiency and guideline adherence and reducing medication errors and ADEs. Strategies for EHR implementation should be therefore recommended and promoted.

Frequency and severity of pain and symptom distress among patients with chronic kidney disease receiving dialysis

QUESTION UNDER STUDY

Data on pain management in haemodialysis patients with end-stage renal disease are scanty. Our study aimed to collect information on the frequency and severity of pain and symptom distress among long-term dialysis patients in southern Switzerland.

METHODS

Patients with chronic kidney disease stage 5, on dialysis, treated in five nephrology units in southern Switzerland, who had given informed consent and were able to complete the survey, were interviewed to assess pain and correlated symptoms using a Visual Analogue Scale (VAS), the Brief Pain Inventory and the Edmonton Symptom Assessment System. To evaluate the impact of symptoms, the Instrumental Activities of Daily Living questionnaire was used.

RESULTS

One hundred and twenty-three patients, aged 36-90 years and with a mean time on dialysis of 3.5 years, were interviewed. Pain was experienced by 81 patients during the 4 weeks before the interview: 68 had chronic pain; 66 reported pain intensity higher than 5 on the VAS; 35 identified musculoskeletal pain as the most disturbing pain. Five patients used drugs to cope with pain during the night. Asthenia and fatigue were prevalent concomitant symptoms. Asthenia, fatigue, sleep disturbances, dyspnoea, loss of appetite, nausea/vomiting and anxiety were correlated with pain. The majority of the patients reported that their pain limited their daily life activities.

CONCLUSIONS

Pain severity and symptom distress in dialysis patients are important, but underestimated and undertreated. They interfere with sleep quality and daily living. Routine assessment of pain burden, pain management similar to that used in palliative care, and adequate analgesic use to treat specific dialysis-associated pain syndromes should be considered in guidelines.

Influence of vibration amplitude on dynamic triggering of slip in sheared granular layers

We perform a systematic statistical investigation of the effect of harmonic boundary vibrations on a sheared granular layer undergoing repetitive, fully dynamic stick-slip motion. The investigation is performed using two-dimensional discrete element method simulations. The main objective consists of improving the understanding of dynamic triggering of slip events in the granular layer. Here we focus on how the vibration amplitude affects the statistical properties of the triggered slip events. The results provide insight into the granular physical controls of dynamic triggering of failure in sheared granular layers.

Outcome of fibrillary glomerulonephritis

QUESTIONS UNDER STUDY

We assessed the long-term follow up of all the patients with fibrillary glomerulonephritis diagnosed since 1992 at our centre of reference for renal pathology in Basel.

METHODS

We performed a retrospective surveillance study with mail questionnaire based follow-up of all patients with the diagnosis of fibrillary glomerulonephritis found in the database of the department of renal pathology in Basel from 1992 to 2007. The outcome was assessed in terms of endstage renal disease (ESRD), death, reduction of proteinuria and improvement of estimated glomerular filtration rate (eGFR).

RESULTS

We obtained sufficient follow up data from 16 out of 20 identified patients. The mean follow up time was 35 months (1-115.1). Six patients died (37.5%), three without having ESRD. Six patients (37.5%) reached ESRD, five of them went on hemodialysis. Thirteen patients (81.3%) received an immunosuppressive therapy with steroids, five of them in combination with cyclophosphamide. The group without immunosuppressive therapy was too small to compare the two groups. In relation to the histological pattern membranous glomerulonephritis (MGN) had a better outcome as compared to the other histological patterns.

CONCLUSIONS

FGN is a heterogeneous disease associated with significant risk of ESRD and mortality. The histological type of the glomerulonephritis may influence the course of the disease.

Fluid balance in critically ill patients. Should we really rely on it?

BACKGROUND

The computation of fluid balances (FBs) by subtracting fluid outputs from inputs is a common critical care practice. Limited information exists about the accuracy and consistency of nurse-registered cumulative FBs and regarding the value of suggested corrections for non-measurable losses.

METHODS

From 147 ICU patients, we prospectively evaluated the cumulative FBs and their relationship to changes in body weight (BW). Standardised measurements of BW were performed on admission and discharge. FB charts were accurately reviewed and arithmetic errors corrected. Net cumulative FBs and adjusted cumulative FBs (considering sensible or insensible fluid losses/fever/liquid faeces) were analysed for all patients and 3 subgroups (cardiac-cerebral, septic, and others). Agreement between FBs and BW changes was calculated according to the defined subgroups and confounding variables.

RESULTS

Cumulative FBs were inaccurate in 49 cases (33%) with errors ranging from -3606 mL to +2020 mL. The total (average daily) difference between measured BW and FBs (mean ± SD) was 0.185±1.874 kg (0.101±1.020 kg). Correlation (r(2)) and Bland-Altman agreement was poor between BW changes and net cumulative FBs (0.552 and -1.26±5.41 kg) and slightly better between BW changes and adjusted cumulative FBs (0.714 and +0.18±3.68 kg). Standard deviations of the average daily differences between BW changes and FBs were always >1 L. Correction of the net FBs as suggested in the literature were not useful. New multiple regression models only modestly improved correlation.

CONCLUSION

For a large portion of patients nurse-registered cumulative FBs are neither accurate nor do they agree with standardised BW measurements. Patient care and clinical decision-making should be based on more objective techniques.

Urinanalysis (UA): a neglected but easy and inexpensive diagnostic tool

The case history of a 75-year-old woman, who was hospitalized with the diagnosis of an acute erosive colitis, is presented. The patient was treated with hysterectomy for an endometrial cancer in 2000 and had suffered from multiple sclerosis for 15 years. A persistent non-productive cough with fever requested a pneumological consultation. Multiple small alveolar opacities and cavitating lesions were found at chest imaging, but no precise diagnosis was possible. Only 3 weeks after hospitalization, we noticed that a urine analysis had been forgotten. This additional test clearly demonstrated a nephritic sediment and further analysis confirmed the diagnosis of a ANCA-positive microscopic polyangiitis, which promptly responded to immunosuppressive therapy. The necessity of a routine urine analysis in the majority of internal medicine patients and the possible link between small vessel vasculitis and multiple sclerosis are discussed.

Comparison of in-hospital secondary prevention for different vascular diseases

BACKGROUND

Secondary prevention of coronary artery disease is highly effective and implemented on a large scale. However, studies testing adherence to recommended secondary prevention of other vascular diseases are rare. Our goal was to evaluate whether the kind of vascular disease influences prescription practice of secondary drug prophylaxis at hospital discharge and to which extent secondary prevention is actually complete.

METHODS

A 3-month prospective observational review of the hospital discharge information of all patients hospitalized because of a vascular disease diagnosis: coronary artery disease (i.e. acute myocardial infarction [AMI] and chronic stable angina [CSA]); peripheral artery disease [PAD] and cerebrovascular disease [CVD]. The analysis was done by board registered internists with a structured form that founded on internationally accepted recommendations.

RESULTS

From 271 patients 191 had coronary artery disease (105 AMI and 86 CSA), 88 PAD and 72 CVD. Global prescription rate (mean; 95% CI) of indicated secondary prophylaxis drugs was 74.1% (69.9-78.2) for AMI, 72.4% (67.2-77.5) for CSA, 74.7% (68.8-80.7) for PAD and 72.1% (66.9-77.3) for CVD. The proportion of patients who were prescribed a complete bundle of recommended medications was globally 29.5% (24.1-35.0).

CONCLUSIONS

We found similar global prescription rates of secondary prevention for the different vascular diseases. However, only one third of the studied collective gets a complete set of required prophylactic drugs.

Omitted and unjustified medications in the discharge summary

BACKGROUND

Limited information exists in regard to drug omissions and unjustified medications in the hospital discharge summary (DS).

OBJECTIVE

To evaluate the incidence and types of drug omissions and unjustified medications in the DS, and to assess their potential impact on patient health.

METHODS

A prospective observational review of the DSs of all patients discharged from our Internal Medicine Department over a 3-month period. Data assessment was made by internists using a structured form.

RESULTS

Of the 577 evaluated DSs, 66% contained at least one inconsistency accounting for a total of 1012 irregularities. There were 393 drug omissions affecting 251 patients, 32% of which were potentially harmful. Seventeen per cent of all medications (619/3691) were unjustified, affecting 318 patients. The unjustified medication was potentially harmful in 16% of cases, occurred significantly more frequent in women than in men (61% vs 50%; p = 0.008) and increased linearly with the number of drugs prescribed (p<0.001). Drug omission had a twofold higher potential to cause harm than unjustified medication.

CONCLUSIONS

Drug omissions and unjustified medications are frequent, and systemic changes are required to substantially reduce these inconsistencies.

Economic burden of unjustified medications at hospital discharge

QUESTION UNDER STUDY

Medication errors are a major concern for health care since they may cause or lead to inappropriate medication use or patient harm. However, little is known regarding the economic burden of unjustified medications.

METHODS

Hospital discharge records of 577 patients were prospectively screened for the presence of unjustified medications. From this sample population, 318 (55%) were eligible and their data were used to assess the monthly costs of unjustified discharge medications, their relationship to the total and each individual's drug expenditure, and the relative cost weights of relevant unjustified drug classes.

RESULTS

The results found that 619 out of 3691 prescriptions (16.8%) were unjustified. The mean (median; 95% CI) monthly costs of unjustified discharge medications were 32 euro (27 euro; 29 euro to 35 euro). The percentage of unnecessary treatments was inversely linked to the amount of total individual drug expenditure. For this collective, monthly extra costs due to unjustified medications were 18585 euro, and the relative cost weights of the relevant drug classes were 45.8% for gastrointestinal agents (33.8% for proton pump inhibitors), 17.7% for cardiovascular drugs, and 17.2% for psychiatric drugs.

CONCLUSIONS

There is a considerable financial burden imposed by unjustified medications at hospital discharge. Discharge medications not motivated by appropriate diagnoses should be questioned. This study should be repeated in other institutions and in a larger population.

Citrate- vs. acetate-based dialysate in bicarbonate haemodialysis: consequences on haemodynamics, coagulation, acid-base status, and electrolytes

Background

A concentrate for bicarbonate haemodialysis acidified with citrate instead of acetate has been marketed in recent years. The small amount of citrate used (one-fifth of the concentration adopted in regional anticoagulation) protects against intradialyser clotting while minimally affecting the calcium concentration. The aim of this study was to compare the impact of citrate- and acetate-based dialysates on systemic haemodynamics, coagulation, acid-base status, calcium balance and dialysis efficiency.

Methods

In 25 patients who underwent a total of 375 dialysis sessions, an acetate dialysate (A) was compared with a citrate dialysate with (C+) or without (C) calcium supplementation (0.25 mmol/L) in a randomised single-blind cross-over study. Systemic haemodynamics were evaluated using pulse-wave analysis. Coagulation, acid-base status, calcium balance and dialysis efficiency were assessed using standard biochemical markers.

Results

Patients receiving the citrate dialysate had significantly lower systolic blood pressure (BP) (-4.3 mmHg, p < 0.01) and peripheral resistances (PR) (-51 dyne.sec.cm^-5, p < 0.001) while stroke volume was not increased. In hypertensive patients there was a substantial reduction in BP (-7.8 mmHg, p < 0.01). With the C+ dialysate the BP gap was less pronounced but the reduction in PR was even greater (-226 dyne.sec.cm^-5, p < 0.001). Analyses of the fluctuations in PR and of subjective tolerance suggested improved haemodynamic stability with the citrate dialysate. Furthermore, an increase in pre-dialysis bicarbonate and a decrease in pre-dialysis BUN, post-dialysis phosphate and ionised calcium were noted. Systemic coagulation activation was not influenced by citrate.

Conclusion

The positive impact on dialysis efficiency, acid-base status and haemodynamics, as well as the subjective tolerance, together indicate that citrate dialysate can significantly contribute to improving haemodialysis in selected patients.

Trial registration

ClinicalTrials.gov NCT00718289

Transition from rolling to jamming in thin granular layers

We study the granular jamming transition for sheared layers of spherical beads ranging in thickness from 1 to 3 times the grain diameter d. As the layer thickness increases slightly above d, the measured friction jumps discontinuously from 0.02 to >0.1, marking the transition from rolling to jamming. Above a critical layer thickness for jamming, the effective granular pressure displays a power law increase with thickness. For thin layers, friction and P increases as the packing fraction decreases near the jamming transition, in contrast to expectations for bulk granular matter.

Haemodynamic consequences of changing bicarbonate and calcium concentrations in haemodialysis fluids

Background. In a previous study we demonstrated that mild metabolic alkalosis resulting from standard bicarbonate haemodialysis induces hypotension. In this study, we have further investigated the changes in systemic haemodynamics induced by bicarbonate and calcium, using non-invasive procedures.

Methods. In a randomized controlled trial with a single-blind, crossover design, we sequentially changed the dialysate bicarbonate and calcium concentrations (between 26 and 35 mmol/l for bicarbonate and either 1.25 or 1.50 mmol/l for calcium). Twenty-one patients were enrolled for a total of 756 dialysis sessions. Systemic haemodynamics was evaluated using pulse wave analysers. Bioimpedance and BNP were used to compare the fluid status pattern.

Results. The haemodynamic parameters and the pre-dialysis BNP using either a high calcium or bicarbonate concentration were as follows: systolic blood pressure (+5.6 and −4.7 mmHg; P < 0.05 for both), stroke volume (+12.3 and +5.2 ml; P < 0.05 and ns), peripheral resistances (−190 and −171 dyne s cm⁻⁵; P < 0.05 for both), central augmentation index (+1.1% and −2.9%; ns and P < 0.05) and BNP (−5 and −170 ng/l; ns and P < 0.05). The need of staff intervention was similar in all modalities.

Conclusions. Both high bicarbonate and calcium concentrations in the dialysate improve the haemodynamic pattern during dialysis. Bicarbonate reduces arterial stiffness and ameliorates the heart tolerance for volume overload in the interdialytic phase, whereas calcium directly increases stroke volume. The slight hypotensive effect of alkalaemia should motivate a probative reduction of bicarbonate concentration in dialysis fluid for haemodynamic reasons, only in the event of failure of classical tools to prevent intradialytic hypotension.

Diagnostic value of serum chromogranin-A combined with MIBG scintigraphy inpatients with adrenal incidentalomas

AIM

Adrenal incidentalomas (AI) are defined as asymptomatic adrenal masses occasionally discovered during high-resolution imaging procedures, as computed tomography or magnetic resonance. Pheochromocytoma, a chromaffin tumour, must be excluded before any invasive diagnostic or therapeutic procedure, in order to avoid dangerous acute catecholamines-release into blood stream. Chromogranin-A (CgA) is a member of the granin family contained in secretory vesicles of chromaffin system. This study investigated the performance of serum CgA in detecting or excluding pheochromocytoma among patients with AI.

METHODS

We enrolled 348 patients by AI > 20 mm without clinical or biochemical signs for corticosteroids overproduction. Serum CgA was assayed by a specific immunoradiometric method and a [123I] metaiodobenzylguanidine (MIBG) scan was performed in the 39 CgA-positive patients.

RESULTS

Eighteen out of these patients showed a positive scan and were submitted to laparoscopic adrenalectomy. Pheochromocytoma was histologically confirmed in all cases . The patients with positive serum CgA, were reassessed 1 year later by clinical examination and serum CgA assay. None of patients developed clinical symptoms of chromaffin-tissue hyperactivity , nor showed a serum CgA increase. Serum levels of CgA were significantly higher inpatients with pheochromocytoma than inpatients without (P<0.0001).

CONCLUSION

We concluded that serum CgA assay is effective as a single marker to detect or exclude sporadic pheochromocytoma among patients with AI > 20mm. Particularly, a negative serum CgA assay may be used to rule out [123I] MIBG imaging and /or other diagnostic procedures.

Renal Artery Assessment with Nonenhanced Steady-State Free Precession versus Contrast-enhanced MR Angiography

PURPOSE

To prospectively assess the diagnostic accuracy of nonenhanced three-dimensional (3D) steady-state free precession (SSFP) magnetic resonance (MR) angiography for detection of renal artery stenosis (RAS), with breath-hold contrast material-enhanced MR angiography performed as the reference standard.

MATERIALS AND METHODS

The study was local ethics committee approved; all patients gave written informed consent. Fifty-three patients (30 male, 23 female; mean age, 58 years) with arterial hypertension and suspected of having RAS were examined with 1.5-T 3D SSFP renal MR angiography. Stenosis grade, maximal visible vessel length, and subjective image quality were compared. Sensitivity, specificity, accuracy, and negative predictive value (NPV) were calculated on artery-by-artery and patient-by-patient bases. The significance of the results was assessed with the paired two-sided t test for continuous variables and with the marginal homogeneity test for categorical variables. Cohen kappa statistics were used to estimate interobserver agreement.

RESULTS

One hundred eight renal arteries with 20 significant (>or=50%) stenoses were detected with contrast-enhanced MR angiography. At artery-by-artery analysis, sensitivity, specificity, accuracy, and NPV of nonenhanced SSFP MR angiography for RAS detection were 100%, 93%, 94%, and 100%, respectively, for observer 1 and 95%, 95%, 95%, and 99%, respectively, for observer 2. Corresponding patient-by-patient values were 100%, 92%, 94%, and 100%, respectively, for observer 1 and 100%, 95%, 96%, and 100%, respectively, for observer 2. Overestimation of stenosis grade with SSFP MR angiography resulted in six and four false-positive findings for readers 1 and 2, respectively. Mean maximal visible lengths of the renal arteries were 69.9 mm at contrast-enhanced MR angiography and 61.1 mm at SSFP MR angiography (P<.001). Both techniques yielded good to excellent image quality.

CONCLUSION

Slab-selective inversion-prepared 3D SSFP MR angiography had high sensitivity, specificity, accuracy, and NPV for RAS detection, without the need for contrast material. However, RAS severity was overestimated in some patients.

Thrombotic thrombocytopenic purpura associated with renal failure after autologous transplantation for multiple myeloma successfully treated with rituximab

Thrombotic thrombocytopenic purpura (TTP) is a haematological syndrome characterised by a dramatic onset requiring an urgent treatment with plasma exchange (PE). However, the prognosis is still dismal for PE related complications, a rate of failure and remarkable frequencies of relapse. TTP post transplantation is largely described as an outstanding, unusual complication of allogenic transplantation, but it is rarely mentioned after autologous transplantation. We describe a 62-year-old Caucasian patient who presented with TTP, accompanied by renal failure, after an autologous transplantation for multiple myeloma. PE together with hemodialysis was rapidly initiated but without any benefit. Since empirical administration of Rituximab, anti CD20 monoclonal antibody,was reported to be effective, we administered four courses of Rituximab inducing a complete remission of TTP and subsequently of the renal failure. This response to Rituximab in TTP post transplantation is suggestive of a possible implication of B-lymphocytes in the pathogenesis of TTP and it paves the way for an investigational approach in this settings.

Would artificial neural networks implemented in clinical wards help nephrologists in predicting epoetin responsiveness?

Background

Due to its strong intra- and inter-individual variability, predicting the ideal erythropoietin dose is a difficult task. The aim of this study was to re-evaluate the impact of the main parameters known to influence the responsiveness to epoetin beta and to test the performance of artificial neural networks (ANNs) in predicting the dose required to reach the haemoglobin target and the monthly dose adjustments.

Methods

We did a secondary analysis of the survey on Anaemia Management in dialysis patients in Switzerland; a prospective, non-randomized observational study, enrolling 340 patients of 26 centres and in order to have additional information about erythropoietin responsiveness, we included a further 92 patients from the Renal Services of the Ente Ospedaliero Cantonale, Bellinzona, Switzerland. The performance of ANNs in predicting the epoetin dose was compared with that of linear regressions and of nephrologists in charge of the patients.

Results

For a specificity of 50%, the sensitivity of ANNs compared with linear regressions in predicting the erythropoietin dose to reach the haemoglobin target was 78 vs. 44% (P < 0.001). The ANN built to predict the monthly adaptations in erythropoietin dose, compared with the nephrologists' opinion, allowed to detect 48 vs. 25% (P < 0.05) of the patients treated with an insufficient dose with a specificity of 92 vs. 83% (P < 0.05).

Conclusion

In predicting the erythropoietin dose required for an individual patient and the monthly dose adjustments ANNs are superior to nephrologists' opinion. Thus, ANN may be a useful and promising tool that could be implemented in clinical wards to help nephrologists in prescribing erythropoietin.

Chronic and acute consequences of a post-dialysis urokinase lock on permanent hemodialysis catheter function

BACKGROUND

To treat permanent hemodialysis (HD) catheter dysfunctions due to thrombosis, as an alternative to pre- and intradialytic instillations/infusions of fibrinolytic agents, for practical reasons, a post-dialysis urokinase lock is often preferred. This study aimed to analyze the consequences on catheter function and the cost/effectiveness of an intermittent post-dialysis urokinase lock.

METHODS

A prospective open experimental study enrolling 10 dialysis patients with a Tesio twin catheter locked with either heparin 5,000 IU/mL or escalating urokinase doses. Catheter function was monitored measuring the blood flow obtained with an aspiration pressure of -180 mmHg for 28 consecutive HD sessions.

RESULTS

No differences were noticed between the blood flow obtained before and after the lock of the catheter with 5000 U/lumen of urokinase (phase 1), but also with 10,000 U/lumen (phase 2) of urokinase. The incidence of catheter dysfunction episodes in the wash-out in the 1st and in the 2nd urokinase phases were, respectively: 13, 6 and 3% (p<0.05 for both 13 vs. 6% and 13 vs. 3%). 47,000 U of urokinase were necessary to avoid one dysfunction episode potentially treatable with an intradialytic urokinase lock of 10,000 U. Between the average blood flow measured in the initial wash out (230 +/- 27 ml/min) and in the 1st (236 +/- 32 ml/min) and also in the 2nd (247 +/- 34 ml/min) urokinase phases significant differences were noticed (p<0.01 and p<0.05, respectively).

CONCLUSIONS

The post-dialysis lock with urokinase is associated with an increase in the catheter blood flow and a re-duction in the occurrence of dysfunction episodes. However, the modest impact on dialysis quality and the apparent unfavorable cost/effectiveness of the prophylactic treatment, call for an investigation of its potential advantages in a larger study.

A new job: research volunteer?

We report three years of experience with a newly introduced register for healthy research volunteers in Canton Ticino, Southern Switzerland. The aim of the register was to encourage responsible participation in medical research, and to detect fraud due to volunteers taking part in more than one study at the same time. All healthy volunteers participating in drug studies approved by the Research Ethics Committee were included in the register and given a special code. During three years, in a population of 1436 volunteers involved in 152 studies, 192 subjects (13.4%) were identified as habitual or regular volunteers (they participated regularly, limiting the pause between studies to the minimum of three months as required by the regulations of the Research Ethics Committee). Among them, only three subjects gave false information and were identified. Most volunteers participated in studies only sporadically (54% in one, 21% in two over three years) and 82.4% of the volunteers were involved, on average, in only one study per year. Our register permits fraud detection as well as analysis of the research population from an epidemiological point of view. It has been well accepted from both volunteers and research organisations. It is simple and represents a substantial contribution especially for organisations, which need to recruit a large number of subjects for their research.

Remember ???a posteriori diagnosis??? of carbon monoxide poisoning

OBJECTIVES

To raise awareness of the possibility of carbon monoxide poisoning as a diagnosis in the emergency department and to present the little known fact that it is possible to diagnose carbon monoxide poisoning retrospectively.

METHOD

Presentation of a case report, review of the literature.

RESULTS

Persistence of elevated carboxyhaemoglobin levels in a stored vacutainer blood sample.

CONCLUSION

Carbon monoxide poisoning is common but often goes unrecognized. This method may help to decrease the number of overlooked cases and thereby possibly prevent further exposure and acute or chronic sequelae.

Vancomycin-induced hypersensitivity reaction with acute renal failure: resolution following cyclosporine treatment

Drug rash with eosinophilia and systemic symptoms or DRESS syndrome is a distinct severe drug-induced hypersensitivity reaction characterized by skin rash, fever, eosinophilia and visceral involvement. The latter leads to a 10% mortality rate, with interstitial nephritis occurring in about 10% of the cases. The outcome is usually favorable after withdrawal of drug therapy; systemic corticosteroid therapy may hasten the recovery, although there are no data from prospective, randomized trials evaluating the efficacy of this approach. Administration of other immunosuppressive agents (cyclophosphamide, cyclosporine) has also been suggested. We report on a patient with vancomycin-induced DRESS syndrome with acute interstitial nephritis and hepatitis. There was no improvement after withdrawal of the offending agent and empiric corticosteroid use. After tapering the steroids, a five-day course of cyclosporine was followed by quick resolution of the skin rash and recovery of renal function. Cyclosporine could represent a treatment option in cases of severe visceral involvement such as persistent renal insufficiency that do not improve after discontinuation of the offending agent and administration of high doses of steroids.

Does bicarbonate transfer have relevant hemodynamic consequences in standard hemodialysis?

BACKGROUND

In a previous study we demonstrated that mild metabolic alkalosis resulting from standard bicarbonate hemodialysis induces hypotension. This study aimed to compare hemodynamic consequences of either a decrease in the dialysate bicarbonate from 32 to 26 mmol/l or an increase in the dialysate calcium of 0.25 mmol/l and to verify whether the calcium shift secondary to alkalemia explains the consequences on blood pressure.

METHODS

In this randomized controlled trial with a single-blind, cross-over design, we used dialysis liquids with two different bicarbonate (32 mmol/l in modalities A and C, and 26 mmol/l in modality B) and calcium (1.25 mmol/l in modalities A and B, and 1.50 mmol/l in modality C) concentrations, and in 27 patients, 243 dialysis sessions, compared blood pressure, heart rate and the incidence of hypotension.

RESULTS

No significant differences were seen between A and B while an increase in systolic and diastolic blood pressures and a decrease in the incidence of hypotension (10.5 vs. 1.2%, p < 0.05) were documented in C. The subgroup of patients who with A showed a lower mean systolic blood pressure received more angiotensin-converting enzyme inhibitors or angiotensin II type-1 receptor blockers (36 vs. 0%, p<0.05) and in C showed a less important increase in systolic and diastolic pressures, but the incidence of hypotensive episodes between A and B was not significantly different (9.1 vs. 15.1%).

CONCLUSIONS

In the present study it was not possible to demonstrate hemo dynamic instability associated with mild metabolic alkalosis. Even in the subgroup showing a lower blood pressure with a higher dialysate bicarbonate, significant hemodynamic or clinical consequences were not noticed. The calcium shift (0.05 mmol/l) related to alkalemia would justify a mean decrease in systolic blood pressure of only about 1 mm Hg.

Predicting intradialytic hypotension from experience, statistical models and artificial neural networks

BACKGROUND

Symptomatic intradialytic hypotension (IDH) associated with increased mortality in hemodialysis patients is difficult to predict and hence prevent. Artificial Neural Networks (ANNs) are promising tools to solve multidimensional non-linear problems. The aim of the study was to verify in which way mathematical models, statistics or knowledge of patients influence the ability of the nephrologists to predict IDH.

METHODS

The performance of ANNs was compared with that of independent nephrologists supported by a logistic regression giving odds ratio for each studied variable (NEPHiS) or of nephrologists in charge of the patients without (NEPHc) or with statistical support as for NEPHiS (NEPHcS). Data from 98 hemodialysis patients were analysed in order to select patients with frequent IDH (>10% of the dialysis sessions). Complete data on 1979 dialysis sessions from 7 patients were retrieved. The ability to predict the occurrence of hypotension episodes was compared (ROC curves) between ANNs, NEPHc/S (N=7) in Switzerland and NEPHiS from independent dialysis centers in Western Australia (N=10).

RESULTS

ANN gave the most accurate correlation between estimated and observed IHD episodes compared to NEPHc (p<0.001), but a similar performance was attained by NEPHcS (p<0.001). NEPHiS were superior to NEPHc (P<0.05), but inferior to ANN (P<0.01). For a sensitivity of 80%, specificity was 44% for ANNs, 33% for NEPHcS and 20% for NEPHc.

CONCLUSIONS

ANNs are superior to nephrologists in predicting IDH episodes; however when supported by a statistical analysis, nephrologists reach ANNs in their prediction ability. IDH still remains difficult to predict even with mathematical models.

A new job: research volunteer?

We report three years of experience with a newly introduced register for healthy research volunteers in Canton Ticino, Southern Switzerland. The aim of the register was to encourage responsible participation in medical research, and to detect fraud due to volunteers taking part in more than one study at the same time. All healthy volunteers participating in drug studies approved by the Research Ethics Committee were included in the register and given a special code. During three years, in a population of 1436 volunteers involved in 152 studies, 192 subjects (13.4%) were identified as habitual or regular volunteers (they participated regularly, limiting the pause between studies to the minimum of three months as required by the regulations of the Research Ethics Committee). Among them, only three subjects gave false information and were identified. Most volunteers participated in studies only sporadically (54% in one, 21% in two over three years) and 82.4% of the volunteers were involved, on average, in only one study per year. Our register permits fraud detection as well as analysis of the research population from an epidemiological point of view. It has been well accepted from both volunteers and research organisations. It is simple and represents a substantial contribution especially for organisations, which need to recruit a large number of subjects for their research.

Pharmacokinetics of N-acetylcysteine following repeated intravenous infusion in haemodialysed patients

OBJECTIVE

N-acetylcysteine (NAC) is a mucolytic agent with anti-oxidant properties. It might have potential positive effects in renal patients and, therefore, its pharmacokinetics and safety in haemodialysis was investigated.

METHODS

Twelve dialysis patients received 2 g NAC (10 ml NAC 20% solution i.v.) mixed with 500 ml saline during the first 3 h of the session for six dialysis sessions. A bolus of heparin was injected intravenously as LWH-heparin. In six patients, one session was repeated with NAC mixed with heparin and infused through the heparin pump.

RESULTS

Baseline NAC was on average 454 ng ml(-1); its concentration increased to 9,253 ng ml(-1) at the second infusion and attained a steady state between 14,000 ng ml(-1) and 17,000 ng ml(-1) at the fourth dose. We observed a C (max) of 53,458 ng ml(-1) with a t (max) of 3.0 h. Plasma clearance was 1.25 l h(-1) and dialytic clearance 5.52 l h(-1). No side effects were observed.

CONCLUSION

In the case of repeated doses, the NAC pre-dose concentration after repeated infusion of 2 g of the drug during the first 3 h of a dialysis session reached the steady state at the fourth infusion, without further accumulation. The dialytic clearance is effective, the total body clearance being reduced to 1.25 l h(-1). In dialysis patients, 2 g NAC given intravenously over 3 h is a safe dosage, with no short-term side effects.

Usefulness of artificial neural networks to predict follow-up dietary protein intake in hemodialysis patients

BACKGROUND

Artificial neural networks (ANN) represent a promising alternative to classical statistical and mathematic methods to solve multidimensional nonlinear problems. The aim of the study was to verify, by comparing the performance of ANN with that of experienced nephrologists, whether ANN are useful tools in hemodialysis to predict the follow-up (=1 month after the observation used for the prediction) dietary protein intake (PCR), and whether their performance is influenced by the size of the population and by the data pool used to built the model.

METHODS

A combined retrospective and prospective observational study was performed in two Swiss dialysis units (84 chronic hemodialysis patients, 500 monthly clinical observations and biochemical test results). Using mathematical models based on linear regressions to evaluate the variables, ANN were built and then prospectively and interinstitutionally compared with the ability of six experienced nephrologists to predict the follow-up PCR.

RESULTS

ANN compared with nephrologists gave a more accurate correlation between estimated and calculated follow-up PCR (P < 0.001). The same superiority of ANN was also seen in the ability to detect a follow-up PCR <1.00 g/kg/day expressed as a percentage of correct predictions, sensitivity, specificity, and predictivity. The interinstitutional performance of the ANN is positively influenced by the size and the variability of the population used to build the mathematical model.

CONCLUSION

The use of ANN significantly improves the ability of the experienced nephrologist to estimate and to detect an unsatisfactory (<1.00 g/kg/day) follow-up PCR. The size of the population selected to build the ANN is critical for his performance.

The favorable effect of regional citrate anticoagulation on interleukin-1beta release is dissociated from both coagulation and complement activation

BACKGROUND

It has been claimed that regional citrate anticoagulation (RCA) improves unfavorable calcium and magnesium dependent cellular and humoral events due to blood/dialyzer membrane interactions during hemodialysis (HD). This study aimed to verify whether the favorable effect of RCA on biocompatibility is independent from coagulation pathway modulation.

METHODS

A randomized controlled cross-over single blind trial comparing the activity of the coagulation pathway (thrombinantithrombin complexes (TAT), fibrinopeptide A (FPA), prothrombin fragments 1+2 (F 1+2) and D-dimer (DD)), complement activation (C3a) and interleukin-1 beta secretion (IL-1beta) in nine chronic HD patients treated with RCA or heparin. Blood samples were obtained from the arterial (C3a, IL-1beta, TAT, F 1+2, FPA and DD) and venous (TAT, F 1+2, FPA) lines 2 min after starting treatment and repeatedly during the procedure after 15 min (C3a and IL-1beta), 30 min (C3a), 45 (C3a) and 180 min (TAT, F 1+2, FPA and DD).

RESULTS

In both treatment protocols significant enhancement was observed in the coagulation activity during the dialysis session, documented by an increase in TAT (p<0.001), F 1+2 (p<0.001) and FPA (p=0.001). Comparing the two anticoagulation modalities, no differences were noticed in the activity of the coagulation pathway, but a significantly higher complement activity (C3a=886 (832-908) vs. 770 (645-857) ng/mL, p<0.05) and lower IL-1beta secretion (235 (206-285) vs. 538 (346-974) pg/mL, p<0.05) was observed in RCA.

CONCLUSIONS

Due to an RCA protocol guaranteeing the same extent of anticoagulation activation as standard heparin, we demonstrated that the significantly lower IL-1beta secretion obtained with RCA is independent from the anticoagulation modulation and dissociated from the complement activity.

Does cystatin C improve the precision of Cockcroft and Gault's creatinine clearance estimation?

BACKGROUND

Cystatin C is increasingly used to estimate renal function, but its large intraindividual variability limits its practical value. This study aimed at verifying whether the clinical practice of associating cystatin C determination with serum creatinine (Cr) improved the ability of the Cockcroft and Gault formula to estimate creatinine clearance (CrCl).

METHODS

It was an observational cross-sectional study of 134 in-patients with mildly impaired renal function. Using the Hoek et al formula (glomerular filtration rate (GFR)/1.73m2 = - 4.32 + 80.35/cystatin C mg/L), multivariate linear regressions (LREG) and artificial neural networks (ANN), we integrated cystatin C in the Cockcroft and Gault formula and analyzed the potential superiority of this procedure by comparing its performance with that of the two algorithms taken separately.

RESULTS

The inclusion of cystatin C in the Cockcroft and Gault formula using the data of an LREG (CrCl = 0.371 x (Hoek et al) + 0.589 x Cockcroft and Gault), a simple mean between the two algorithms or ANN ameliorated the CrCl estimation precision allowing an absolute error reduction of approximately 4, 4 and 6%, respectively (relative values 12, 12 and 17%).

CONCLUSIONS

Although the combination of the Hoek et al and Cockcroft and Gault formulae using both linear and non-linear mathematical methods allowed a statistically significant reduction in the estimation error generated by Cockcroft and Gault, considering the small impact on the estimation precision and the large intraindividual variation of both cystatin C and Cr, this procedure probably has no clinical relevance.

Thrombus aspiration as a bailout procedure during percutaneous renal angioplasty

PURPOSE

To present a case in which thrombus aspiration, urokinase, and abciximab were used to recanalize a sudden acute thrombotic occlusion of the right renal artery during percutaneous renal angioplasty.

CASE REPORT

A 72-year-old man with severe arterial hypertension, impaired renal function, and peripheral artery disease was referred for interventional renal revascularization of a proximal stenosis of the right renal artery. Predilation was unsuccessful, and stent placement was followed by immediate occlusion of the distal renal artery, probably due to dislocation of a mural thrombus. Since intra-arterial administration of urokinase (300,000 IU) was ineffective, thrombus aspiration was performed using the 7-F guiding catheter. After successful removal of the thrombus, abciximab was given intravenously. Control angiograms showed recanalization of the stented segment and patency of the distal renal arteries, an outcome confirmed 8 months later by duplex ultrasound.

CONCLUSIONS

As demonstrated in our case, thromboembolic complications can be rapidly and successfully treated on the table by combined measures, such as catheter thrombus extraction and pharmacological strategies.

Does monitoring of pre-/post-dialyzer pressure difference improve efficiency in intermittent hemodialysis?

BACKGROUND

Continuous monitoring of pre-/post-dialyzer pressure difference (DeltaP) is widely used in continuous renal replacement therapies to monitor extracorporeal circuit function. The aim of this study was to verify whether DeltaP may help to identify chronic subclinical worsening of dialysis quality due to incomplete dialyzer clotting in intermittent hemodialysis.

METHODS

Nine chronic hemodialysis patients were enrolled in the study and dialyzed twice (high-flux polysulfone dialyzer) with DeltaP and urea-clearance monitoring: the first session with a standard anticoagulation and the second without. To verify whether a visible clotting of the dialyzer precedes or follows a significant DeltaP increase, we checked the dialyzers for the presence of red clots after a saline flush performed when a 50% increase in DeltaP was registered.

RESULTS

In the second dialysis session after a 50% increase in DeltaP (documented in 7/9 patients), all dialyzers, after saline flush, showed a visible fiber clotting but not a significant reduction (>15%) in urea clearance. In the majority of the patients (6/7), until a few minutes before complete occlusion of the extracorporeal circuit, the urea clearance did not change significantly (-8.9 +/- 12.7%).

CONCLUSIONS

The usual check of the presence or absence of red clots in the dialyzer at the end of the dialysis session is enough, in the absence of red clots, to ensure that dialyzer efficiency is maintained during the whole treatment. Contrary to what is applied in CRRT, a continuous monitoring of DeltaP during intermittent hemodialysis would not significantly help to unmask unnoticed inefficient hemodialysis sessions.

The degree of predictivity in pilot studies on six subjects in bioequivalence trials

This study, based on computer simulations, analysed the degree of predictivity of pilot trials on six subjects, with the idea of a further pivotal trial on 18 or more volunteers aimed at assessing bioequivalence. Volunteers enrolled in 10 pivotal bioequivalence trials were considered. For every trial, a thousand bootstrap samples were generated to simulate trials with six subjects, while keeping a balanced design for sequence, period and formulation. Then a standard ANOVA for crossover trials, with 90% confidence intervals for the ratios, was done on C(max) and AUC for each simulated trial. The number of subjects needed to achieve bioequivalence was based on the residual error of the ANOVA. When this number was smaller or equal in the case of bioequivalence, or larger in the case of insufficient evidence to conclude on bioequivalence, to the number of the subjects enrolled in the original trial, the subgroup was considered predictive. Otherwise it was considered non-predictive.The average predictivity index, calculated by dividing the number of predictive findings by the total number of subgroups, in our case 1000, and multiplying the result by 100, was 71.1% for C(max) and 82.9% for AUC. Results of the simulations suggest that pilot trials on six volunteers can be useful for predicting the pool size of volunteers in bioequivalence trials, and for in vivo-in vitro correlation studies in pharmaceutical development strategy.

Artificial neural networks improve the prediction of Kt/V, follow-up dietary protein intake and hypotension risk in haemodialysis patients

BACKGROUND

Artificial neural networks (ANN) represent a promising alternative to classical statistical and mathematical methods to solve multidimensional non-linear problems. The aim of the study was to compare the performance of ANN in predicting the dialysis quality (Kt/V), the follow-up dietary protein intake and the risk of intradialytic hypotension in haemodialysis patients with that predicted by experienced nephrologists.

METHODS

A combined retrospective and prospective observational study was performed in two Swiss dialysis units (80 chronic haemodialysis patients, 480 monthly clinical observations and biochemical test results). Using mathematical models based on linear and logistic regressions as background, ANN were built and then prospectively compared with the ability of six experienced nephrologists to predict the Kt/V and the follow-up protein catabolic rate (PCR) and to detect a Kt/V < 1.30, a follow-up PCR < 1.00 g/kg/day and the occurrence of hypotension.

RESULTS

ANN compared with nephrologists gave a more accurate correlation between estimated and calculated Kt/V and follow-up PCR (P<0.001). The same superiority of ANN was also seen in the ability to detect a Kt/V < 1.30, a follow-up PCR < 1.00 g/kg/day and the occurrence of hypotension expressed as a percentage of correct answers, sensitivity, specificity and predictivity.

CONCLUSIONS

The use of ANN significantly improves the ability of experienced nephrologists to estimate the Kt/V and the follow-up PCR and to detect a Kt/V < 1.30, a follow-up PCR < 1.00 g/kg/day and the occurrence of intradialytic hypotension.

Unexpected haemodynamic instability associated with standard bicarbonate haemodialysis

BACKGROUND

The bicarbonate concentration in dialysis fluids for intermittent haemodialysis usually is between 32 and 35 mmol/l. The severity of chronic metabolic acidosis secondary to end-stage renal failure is very variable, however, so that in some patients pre-dialysis acidosis is overcorrected. This study aimed to analyse haemodynamic tolerances to metabolic alkalosis during intermittent haemodialysis.

METHODS

In this randomized controlled trial with a single blind, cross-over design, we used dialysis liquids with two different bicarbonate concentrations, 32 (modality A) and 26 (modality B) mmol/l, and in 26 patients, 468 dialysis sessions, compared blood pressure, heart rate, incidence of hypotension and the frequency of corrections required with saline or hypertonic glucose infusions.

RESULTS

The results of intradialytic haemodynamic monitoring for modalities A and B, respectively, were: lowest systolic blood pressure 120.8+/-20.8 vs 124.3+/-20.6 mmHg (P < 0.01); mean systolic blood pressure 138.5+/-23.8 vs 144.6+/-24.8 mmHg (P < 0.001); and highest heart rate 73.5+/-12.0 vs 75.8 +/- 12.9 (NS); with modality A, patients had more dialysis sessions with hypotensive episodes (5.55 vs 1.7%, P < 0.05) and required more saline or hypertonic glucose infusions (20.9 vs 13.7% of the dialysis sessions, P < 0.05).

CONCLUSIONS

Mild metabolic alkalosis resulting from standard bicarbonate haemodialysis (32 mmol/l) may induce symptomatic hypotension. While normalizing chronic metabolic acidosis is desirable, reducing bicarbonate concentrations should be considered in cases of significant alkalaemia or otherwise untreatable haemodynamic instability.

Does continuous venovenous hemodiafiltration concomitant with radiological procedures provide a significant and safe removal of the iodinated contrast ioversol?

BACKGROUND

The purpose of our study was to investigate whether continuous venovenous hemodiafiltration (CVVHDF) concomitant with radiological procedures (RxP) was feasible, well tolerated and could significantly remove iodinated contrast media (CM).

METHODS

26 patients with various degrees of renal insufficiency who were submitted to RxP were included in the study. The CVVHDF session was started immediately before CM administration. All the patients were evaluated for feasibility and tolerability; furthermore a pharmacokinetic study was done on 12 patients to calculate the amount of CM eliminated. The baseline incidence of CM nephropathy was studied in 25 consecutive historical controls.

RESULTS

The CM administered was 208 +/- 146 g; the fractional removal of CM was 9.2 +/- 4.9% during RxP and 30.9 +/- 20.7% during the whole CVVHDF session. Hemodynamic tolerance was excellent. The incidence of CM nephropathy in the experimental and control groups was 37 and 24%, respectively.

CONCLUSIONS

CVVHDF during RxP is feasible and well tolerated but ioversol removal is modest. This fact together with the high incidence of renal function impairment, the complexity of the procedure and its intrinsic risks, and the large amount of resources needed discourage the routine use of CVVHDF as a prophylactic tool to avoid CM nephropathy.

Citrate anticoagulation in continuous venovenous hemodiafiltration: a metabolic challenge

OBJECTIVE

Feasibility and safety evaluation of regional citrate anticoagulation (RCA) versus systemic heparinization for continuous venovenous hemodiafiltration.

DESIGN AND SETTING

Combined retrospective and prospective observational study performed in a secondary multidisciplinary intensive care unit of the Ospedale Civico Lugano Switzerland.

PATIENTS AND INTERVENTIONS

Twelve hemodynamically unstable patients (median APACHE II score 26, interquartile range 22-29) in whom heparin was judged to be at least temporarily contraindicated. A switch from RCA (predilution setting; same iso-osmotic replacement and dialysis fluid) to heparinization or vice versa was recommended for the final evaluation; 56 dialyzers were used for RCA (1,400 h) and 39 for heparinization (1,271 h).

MEASUREMENTS AND RESULTS

Median dialyzer life span was 24.2 h (interquartile range 17.4-42.3) for RCA and 42.5 h (20.6-69.1) for heparinization. Fluid control and dialysis quality were similar in the two groups and required no additional intervention. The risk of significant hypocalcemia and metabolic alkalosis was higher at the beginning of the RCA program and decreased with the further training of the staff. Seven bleeding episodes occurred with heparinization vs. three in RCA.

CONCLUSIONS

RCA may be a safe and useful form of anticoagulation which is more expensive than heparinization but helps to minimize bleeding risk. The risk of metabolic complications is higher at the beginning of a new RCA program. For centers lacking experienced staff we suggest reserving this technique for patients with rapid clotting of the extracorporeal circuit if treated without anticoagulation.