Acute acalculous cholecystitis on a COVID-19 patient: a case report

INTRODUCTION

We report an extremely rare case of acute acalculous cholecystitis on a COVID-19 patient. In our knowledge, this is the first report of laparoscopic cholecystectomy performed on a COVID-19 patient.

PRESENTATION OF CASE

A COVID-19 patient was diagnosed with acute acalculous cholecystitis and a multidisciplinary team decided to perform a percutaneous transhepatic biliary drainage (PTBD) as the first treatment. SARS-CoV-2 RNA was not found in the bile fluid. Because of deterioration of the patient's clinical conditions, laparoscopic cholecystectomy had to be performed and since the gallbladder was gangrenous, the severe inflammation made surgery difficult to perform.

DISCUSSION

Acalculous cholecystitis was related with mechanical ventilation and prolonged total parenteral nutrition, in this case the gangrenous histopathology pattern and the gallbladder wall ischemia was probably caused by vascular insufficiency secondary to severe acute respiratory distress syndrome of COVID-19 pneumonia. The percutaneous transhepatic gallbladder drainage (PTBD) was performed according to Tokyo Guidelines because of high surgical risk. Laparoscopic cholecystectomy was next performed due to no clinical improvement. The absence of viral RNA in the bile highlights that SARS-CoV-2 is not eliminated with the bile while it probably infects small intestinal enterocytes which is responsible of gastrointestinal symptoms such as anorexia, nausea, vomiting, and diarrhoea.

CONCLUSIONS

Although the lack of evidence and guidelines about the management of patient with acute cholecystitis during COVID-19 pandemic, laparoscopic cholecystectomy, at most preceded by PTGBD on high surgical risk patients, remains the gold standard for the treatment of acute cholecystitis on COVID-19 patients.

Beta 2-microglobulin Removal by Synthetic Dialysis Membranes. Mechanisms and Kinetics of the Molecule

Beta 2-microglobulin (ß2-m) accumulation represents a possible complication of long term dialysis. It is therefore important to evaluate the capacity of removal of this molecule from the patient by different dialysis membranes. The present study is aimed at evaluating the mechanisms involved in ß2-m removal by three different synthetic membranes: a) highly asymmetric hydrophobic polysulfone (Biosulfane, NMC), b) moderately asymmetric and hydrophobic polysulfone (PS600, Fresenius), c) Polyacylonitrile (AN69HF, Hospal). The adsorption capacity and sieving coefficients of the three membranes for native and labeled ß2-m were studied in vitro utilizing human blood. The amount adsorbed by the membrane was measured by the elution of the molecule obtained with a detergent solution. Clearances, total removal and membrane adsorption were studied in six patients treated in a randomized sequence with the three membranes. For this purpose, plasma and dialysate measurements as well as total collection of spent dialysate and ß2-m elution from the used dialyzers were carried out. Ex novo generation of ß2-m did not take place during in vitro circulation. The molecule was removed by the studied membranes both by filtration and adsorption. The Biosulfane membrane removed ß2-m mostly by adsorption while the PS600 membrane removed ß2-m almost entirely by filtration. Intermediate behaviour was shown by AN69 membrane. Similar quantities of ß2-m were removed from the patients with the three membranes. Total removal could only be precisely measured by adding the quantity of ß2-m eluted from the membrane to the amount recovered in the spent dialysate. Out of total removal, adsorption was more than 90% with Biosulfane, while only 5% with the PS600. These findings contribute to the understanding of the discrepancy found between the clearance measured from the plasma side and that measured from the dialysate side. In conclusion, clearance and sieving measurements for ß2-m cannot be correctly performed unless the capacity of adsorption of the membrane is taken into account.

Comparison of Four Different Short Dialysis Techniques

The goal of shortening dialysis treatment time has stimulated the development of new, highly efficient dialytic strategies. In this study the Authors compared four different short dialysis treatments in terms of efficiency, clinical tolerance, technological investment and costs: 1) Rapid bicarbonate dialysis with 1.5 sq.m. cuprophane membrane; 2) High flux biofiltration with 1.2 sq.m. AN69S hollow fiber membrane; 3) Hemodiafiltration with 1.2-1.9. sq.m. polysulphonic hollow fiber hemodiafilters, and 4) High flux hemodiafiltration with two serial hemodiafilters with AN69s membrane (total 2.4 sq.m.).

Hydraulic properties and solute clearances at different blood flows (300-500 ml/min) were tested for each technique. Once the optimal operative level was established three patients were treated with each technique for at least six months. Since BUN clearance averaged 310 ml/min, the treatment duration varied from 120 to 180 min/session with KT/V always higher than 1. The average protein catabolic rate was 0.9 g/kg/24h. Clinical tolerance was generally good, slightly better in treatments with a high convective component. Despite the greater efficiency of treatment No. 4, the technological requirements and costs are such that the others are currently more feasible and acceptable in clinical routine.

The study demonstrates that reduction of dialysis treatment time is possible in all centres in a selected population with adequate blood access. Treatment No. 1 can even be performed with standard equipment and cuprophan membranes, while bicarbonate in the dialysate is mandatory. The real limit to shortening treatment time seems to be related to the maximal rate of ultrafiltration achievable in the patient during dialysis.

Anatomical Bases of Peritoneal Permeability: A Reappraisal. Anatomy of Peritoneum

The peritoneal membrane consists of flat mesothelial cells linked together with digitations and containing vesiculae with pinocytic capacity, of endothelial cells (containing Weibel-Palade's bodies and vesiculae) and of an interstitial tissue consisting of a network of watery channels.

The cellular structures of mesothelium and endothelium are characterized by tight and gap junctions or perhaps by macular junctions. The visceral peritoneum shows a prevalence of gap junctions, the pericytic veins contain only tight junctions while both types can be found in the arterioles.

Two different ways for solute transport are theoretically possible: the vesicles of plasmalemma (via pinocytosis) and the junctions (via size-sieving effect). Studies with tracers did not furnish unequivocal data on this problem and did not clarify if these structures could be the equivalent of the pores of the Landis-Pappenheimer's theory. The studies of Karnowsky and Simionescu, using tracers, have in fact given opposite results.

The role of Neurotransmitters in the Genesis of Uremic Encephalopathy

To classify the influence of neurotransmitters in the genesis of uremic encephalopathy we studied cerebrospinal fluid (CSF) and plasma (P) amino acid (AA) concentration, in patients undergoing various dialytic treatments (hemodialysis = HD, intermittent and continuous peritoneal dialysis = IPD and CAPD).

HD causes a significant decrease in CSF/P ratios of branched chain AA (BCAA) and a significant increase in CSF Glycine/Valine ratio, suggesting an augmented brain uptake of Glycine at detriment of Valine. In IPD the general trend of Aromatic AA/BCAA ratio suggests a preferentilal transport of Aromatic AA through the blood brain barrier. The differences between IPD and HD are confirmed by data concerning metabolites of Serotonin and Dopamine: CSF concentrations of 5-Hydroxyndoleacetic acid and Homovanillic acid are low in HD but high in IPD.

So, a reduced (in HD) and an increased (in IPD) activity of monoamine systems could be at the basis of some neurological disturbances appearing in uremia.

Technical and clinical evaluation of a new polyamide hollow fiber hemofilter for CAVH

We carried out an in-vivo and in-vitro evaluation of a new polyamide hollow fiber hemofilter especially designed to operate under conditions of low pressure and low blood flow, such as in continuous arteriovenous hemofiltration (CAVH).

The results obtained suggest that this filter is a prototype of a new generation of hemofilters especially designed for CAVH. Its low resistance permits its use even in patients with severe hypotension. The high blood flows achieved at a given pressure reduce the risk of clotting and increase the ultrafiltration rate. When an average ultrafiltration of 20-25 ml/min is achieved in 24 hours CAVH becomes very efficient, and alternative techniques to increase its efficiency are no longer required.

Hyperprolactinemia as a Marker of Neurotransmitter Imbalance in Uremic Population

Serum prolactin (PRL) levels are elevated in patients with chronic renal failure (CRF) but the mechanisms responsible for these abnormalities are not fully understood. PRL secretion is undoubtedly influenced by many substances, which can be variously altered in uremia: monoamines, endogenous opiates and PTH. Our data suggest that in early renal failure PRL levels are already significantly high and the 24-h pattern of PRL secretion is significantly different from that in controls.

PRL derangements could be due in mild renal failure, to unknown factors (GABA?); in severe CRF, to a major change in dopaminergic activity; in hemodialysis (HD), to a low turnover of monoamines, and in peritoneal dialysis (PD) to increased activity of sero-toninergic and dopaminergic systems.

Technical and Clinical Evaluation of a New Asymmetric Polysulfone Membrane (Biosulfane®)

First generation asymmetric polysulfone membranes had high hydraulic permeability (kf=40 ml/h/mmHg/sqm) but a low diffusive permeability due to the hydrophobic nature and wall thickness of 75–100 microns. We have tested a new polysulfone membrane with a wall thickness of 40 microns in a series of in vitro and in vivo dialysis session experiments. The new “Biosulfane®” membrane presented a Kf of 45.8 with constant performance up to 240 mins. The koA was 760 and the clearance value at 350 ml/min of Qb in hemodiafiltration was 255 ml/min for urea, 210 for creatinine, 225 for phosphate, 76 for inulin. In high flux dialysis the clearances were similar except for inulin which was 32% lower due to the lower convection amount. Beta-2 microglobulin clearance was 22 ml/min in high flux dialysis and 37 in hemodiafiltration. Solute sieving coefficients were close to 1 for the majority of the studied solutes in a wide range of molecular weights and slight variations were observed for charged solutes due to Donnan's effect. The sieving for Inulin was 0.96 while that for Beta-2 microglobulin was not measurable due to a large molecule adsorption on the inner structure of the fibres. The good performances of this membrane are probably due to reduced wall thickness and a consequent improvement in diffusive permeability to small size solutes.

Solute and Water Transport during Continuous Arteriovenous Hemofiltration (CAVH)

The transport mechanisms governing solvent and solute removal during CAVH were elucidated on the basis of in vitro and in vivo observations.

Using a typical hemofilter (Diafilter D-20, AMICON), filtration rate rose with inlet blood flow rate until an asymptote was reached at blood flows of approximately 150 ml/min. The onset of the asymptote coincided with transition from a regime controlled by oncotic pressure (filtration pressure equilibrium), to one governed by simple Darcy's law filtration behaviour. Subsequent measurements showed that under clinical conditions, CAVH is generally in the pre-asymptotic regime and operates at filtration pressure equilibrium.

These observations offer the theoretical bases for a new design for CAVH hemofilters.

As a possible corollary, middle-molecule sieving coefficients were found to be stable with time during CAVH in vivo, whereas in chronic mechanical hemofiltration they declined significantly during clinical treatment. The sieving coefficients, however, were lower in mechanical hemofiltration from the beginning of the session.

These observations suggest that the measured sieving coefficient for a membrane is not necessarily a constant directly and solely related to the membrane standard reflection coefficient for a given solute. Concentration polarization and the ultrafiltration rate per unit of surface area may in fact have a major effect on the final concentration of solutes in the ultrafiltrate.

Dialysate Flow Distribution in Hollow Fiber Hemodialyzers with Different Dialysate Pathway Configurations

The efficiency of a hemodialyzer is largely dependent on its ability to facilitate diffusion, since this is the main mechanism by which small solutes are removed. The diffusion process can be impaired if there is a mismatch between blood and dialysate flow distribution in the dialyzer. The objective of the paper was to study the impact of different dialysate compartment designs on dialysate flow distribution and urea clearances.

Eighteen hollow fiber 1.3 m2 hemodialyzers were studied, 6 each of 3 designs: Type A- standard fiber bundle (PAN 65DX Asahi Medical, Tokyo, Japan); Type B - spacing filaments external to the fibers (PAN 65SF Asahi Medical, Tokyo, Japan); Type C - fibers waved to give Moiré structure (FB130 Nissho-Nipro, Osaka, Japan). In vitro studies: 3 dialyzers of each type were studied following dye injection into the dialysate compartment. Dynamic sequential imaging of longitudinal sections of the dialyzer were undertaken, using a new generation helical CT scanner (X-Press/HS1 Toshiba Corporation, Tokyo, Japan). In vivo studies: 3 dialyzers of each type were studied, in randomized sequence, in 3 different patients under standardized dialysis conditions. Blood- and dialysate-side urea clearances were measured at 30 and 150 minutes of treatment.

Macroscopic and densitometrical analysis revealed that flow distribution was most homogeneous in the dialyzer with Moiré structure (Type C) and least homogeneous in the standard dialyzer (Type A). Space yarns (Type B) gave an intermediate dialysate flow distribution. Significantly increased urea clearances (p<0.001) were seen with Types B and C, compared to the standard dialyzer. Type C (Moiré) had the highest clearances although these were not significantly greater than Type B (space yarns).

In conclusion, more homogeneous dialysate flow distribution and improved small solute clearances can be achieved by use of spacing yarns or waved (Moiré structure) patterns of fiber packing in the dialyzer. These effects are achieved probably as a result of reduced dialysate channeling resulting in a lower degree of mismatch between blood and dialysate flows. The new radiological technique using the helical CT scanner allows detailed flow distribution analysis and has the potential for testing future modifications to dialyzer design.

Dynamic Catheterography in the Early Diagnosis of Peritoneal Catheter Malfunction

The dynamic catheterography is an imagin technique that allows to study the peritoneal solution inflow and outflow phases in case of catheter malfunction. The examination is carried out in three subsequent steps: 1) direct examination without contrast media in order to define the position of the catheter inside the abdomen; 2) low speed catheterography by normal injection of 10 ml of hydrosoluble contrast medium to verift the patency of the cannula; 3) high speed catheterography by 30 ml hydrosoluble dye injected with an automateds high pressure system to study the inflow phase, the fluid distribution in the peritoneal cavity and the patency of the catheter holes. Different radiographic patterns can be found: dislocation of the catheter tip, KinKing, one way obstruction, inner lumen obstruction. The procedure is simple, safe and reliable for a correct diagnosis and for the choice of a successfull therapeutic approach to peritoneale catheter malfunction.

In Vitro and in Vivo Evaluation of a New Polysulfone Membrane for Hemodialysis. Reference Methodology and Clinical Results: (Part 1: In Vitro Study)

Different high flux membranes have been recently developed. The present study is aimed at describing the technical features and the clinical performances of a new high flux polysulfone membrane (T-sulfone, Toray Japan). The study has been carried out on two different dialyzers (surface area = 1.3 and 1.8 m2). The filters have been tested in vitro under definite experimental conditions. The hydraulic flow resistance, the pressure drop in the blood compartment and the hydraulic permeability have been determined in a wide range of in vitro experimental conditions. The in vitro sieving coefficients for various solutes have also been determined utilizing human blood. Hydraulic permeability was found in the range of 28.4 ml/h/mmHg/m2 and sieving coefficients were between 0.96 and 1.0 for all low molecular weight solutes. The sieving coefficient for inulin was 0.95. The pressure drop in the filter at 300 ml/min of blood flow was 95 mmHg for the 1.3 m2 and 57 mmHg for the 1.8 m2. The filters are then designed to operate in the presence of high blood flows without excessive resistance in the blood compartment. The blood compartment analyzed by means of a special radiological sequence obtained with a helical scanner after dye injection confirmed the homogeneous distribution of the blood flow in several cross sections of the bundle. Adequate distribution of dialysate was confirmed with a similar method applied to the dialysate compartment. The new imaging techniques utilized were greatly helpful to determine adequacy of filter design and flows distribution.

Choosing New Adsorbents for Endogenous Ultrapure Infusion Fluid: Performances, Safety and Flow Distribution

Adsorption may notably contribute to the removal of uremic toxins and to the efficiency of hemodialysis. We examined different uncoated stationary matrixes, charcoals and synthetic resins to establish their adsorptive capacities in relation to low (urea, creatinine) and high molecular weight (β2-microglobulin, myoglobin) compounds in in vitro conditions (steady state and flow-through) using isotonic solutions or uremic ultrafiltrate. Trace metal, particle release analyses and scanning electron microscopy of different adsorbents were performed. Dynamic flow-distribution studies were made using 99Technetium and analysing the different regions of interest by single head γ-camera. We show that adsorbents may differ greatly as to their adsorptive capacity depending on flow rate, nature, and total mass of the compounds to be removed from the ultrafiltrate. These studies suggest a methodological approach for screening stationary matrixes for possible application in hemodialysis.

Double Pass Dialysis: A New Method of Renal Replacement in Patients with Malfunctioning Vascular Access

Several patients undergoing chronic renal replacement therapy present problems related to their vascular access. Low blood flows and high rates of recirculation are common in such patients in which, for this reason, it becomes difficult to apply highly efficient techniques or techniques where diffusion and convection are combined as in hemodiafiltration. In these patients we studied the possibility of partially recirculating the blood in the extracorporeal circuit in order to increase the flow rate per single hollow fiber; we defined our system “double pass dialysis”. We evaluated the system's efficiency in 12 patients during 24 dialysis sessions: 12 high flux dialysis sessions (without reinfusion) and 12 hemodiafiltration sessions (9 liters reinfusion). Different surfaces of polyacrylonitrile dialyzers were utilized (1.3-1.7-2.1 sqm) at 250 and 350 ml/min of blood flow with or without 100 ml/min of recirculation. During each dialysis session blood and dialysate samples were taken in order to calculate BUN, Creatinine, Phosphate and Inuline clearances from both the blood and dialysate side. The clearances of low molecular weight solutes were not really influenced by the artificial increase of the blood flow, but on the other hand, the clearances of higher molecular weight solutes increased from 10 to 30% during both high flux dialysis and hemodiafiltration with recirculation. This increase was evident mostly in hemodiafiltration suggesting that the cleaning effect on the membrane has a positive impact on the permeability. The good clinical results obtained with the double pass dialysis show that the system is safe and reliable and may become a valid support in critical situations in order to reach adequate dialysis treatment.

On line filtration of dialysate: structural and functional features of an asymmetric polysulfone hollow fiber ultrafilter (Diaclean®)

The endotoxin transfer across dialysis membranes has been investigated using specific in vitro circuits. Backdiffusion and backfiltration have been analyzed and most dialysis membranes have shown to be permeable to LAL positive substances. Synthetic membranes however display the better capacity of retention of these products despite their higher porosity and permeability. For such reason synthetic polysulfone ultrafilters are used as pyrogen filters to obtain ultrapure dialysate. We have investigated the characteristics of a polysulfone ultrafilter named Diaclean and manufactured by Amicon Ireland. The capacity of endotoxin retention has been investigated both in filtration and backfiltration modes on new and used ultrafilters. The capacity of endotoxin adsorption was investigated as well. Used ultrafilters appeared to maintain the retention capacity and the adsorption capacity up to 4 months of use. Only slight differences were noted from the baseline values (p = n.s.). The best adsorption capacity is always displayed by the outer layer of the membrane suggesting its best utilization in back filtration mode with tangential flow. No morphological changes were observed in the used membrane analyzed by scanning electron microscopy.

On-Line Urea Monitoring: A Further Step towards Adequate Dialysis Prescription and Delivery

The Aim Of This Study Is To Present A Clinical Experience Carried Out With A New Device Designed To Measure On-Line Urea Nitrogen Concentration In The Effluent Dialysate. The Biostat 1000® Urea Monitor (Baxter Healthcare, Dirfield, Iii, Usa) Was Utilized In The Present Study. The Monitor Is Based On The Principle That Multiple Urea Measurements In The Dialysate Effluent From The Dialyzer, Permit To Built A Double Exponential Regression Leading To The Urea Kinetic Parameters Of The Dialysis Session. Data Obtained With The Urea Monitor Were, In The Present Study, Compared With Those Obtained By Direct Measurements Carried Out In Blood And Dialysate And By The Collection Of The Whole Amount Of Spent Dialysate. The Monitor Provided An Accurate Value Of Predialysis Bun Without Any Blood Drawing. Urea Kinetics Were Established From Multiple Dialysate Measurements And No Blood Drawing Was Necessary. The Double Pool Kinetics Were Taken Into Account And Kt/V, Pcr And Sri° Obtained Were Comparable To Those Obtained From Direct Measurement. Since A Projected Value Of Kt/V Can Be Obtained, The Monitor Could Represent A Potential Source Of Information To Detect Possible Filter And Machine Dysfunction, As Well As High Rate Of Recirculation.

A New Blood Module for Continuous Renal Replacement Therapies

A new blood module for continuous renal replacement therapies has been utilized to perform CVVH in critically ill patients. The features of the new module named (HP300 and manifactured by Medica srl (Medolla, Modena) are the easy installation and transportability to the bedside, the simple and safe management and the continuous measurement of the pre and post filter pressure with automatic calculation of the end-to-end pressure drop inside the filter. The last feature permits to detect early malfunctions of the filter due to fibers clotting or due to the internal coating of the hollow fibers by plasma proteins. In both cases the efficiency of the treatment can be reduced because of a significant reduction of the ultrafiltration rates or a remarkable decay of the membrane permeability and solute sieving coefficients. In many cases this reduction is only detected when important effects on solute removal have already occurred. In our experience, the new module permitted the substitution of the filters when early malfunctions were detected and maximal treatment efficiency was therefore guaranteed over extended periods of time.

Impact of Spacing Filaments External to Hollow Fibers on Dialysate flow Distribution and Dialyzer Performance

A new type of dialyzer (PAN 650 SF Asahi) is analyzed in terms of hydraulic properties, solute clearances and dialysate flow distribution. The new type of dialyzer is a polyacrylonitrile hollow fiber filter, equipped with spacing filaments placed externally to the fibers to facilitate dialysate distribution and avoid channeling. The new filter is compared with a similar filter without spacing filaments. For this purpose, blood and dialysate side clearances have been measured in sequential dialysis session carried out randomly in the same patients. Furthermore, a last generation helical scanner (X-Press / HS1, Toshiba) has been utilized to analyze in vitro the flow distribution of dialysate inside the dialyzer. A contrast medium was injected and a sequence of images has been achieved on a longitudinal section of the dialyzer. This new method permits to avoid any bias due to the cylindrical shape of the dialyzer, since a 10 mm thick rectangular section is analyzed and not the entire body of the filter. The dialyzers equipped with spacing filaments displayed a significant improvement of the dialysate distribution as demonstrated by the radiological pattern. In detail, despite a channeling phenomenon in the peripherical region of the bundle is still present, this is remarkably reduced in comparison with the channelling phenomenon observed in the standard dialyzers. This improved distribution is confirmed by a significant improvement of the solute clearances.

Slow Maturation of Arterio-Venous Fistula in Seven Uremic Patients: Use of Ash Split Cath® as Temporary, Prolonged Vascular Access

The temporary vascular access is the essential condition required to perfrom hemodialysis in uremic patients in the absence of a permanent and utilizable vascular access. The cannulation of a central vein with a dual lumen catheter may be useful when a few weeks are required for the maturation of AVF. Longer times for AVF maturation (such as in diabetic patients and in aged patients) impose the use of a tunnelled catheter such as Tesio Catheter or Hickman Catheter which lead to minor complications and more efficient dialysis treatment. The Ash Split Cath®, a recently introduced chronic hemodialysis catheter, provides dialysis via a transcutaneous portion containing a 14 French cylindrical shaped catheter with D-shaped lumens and a dacron cuff.

Due to the slow maturing of AVF, in our Department the Ash Split Cath has been used in 7 uremic patients (3 males and 4 females) who required hemodialysis.

The cannulation of the internal jugular vein was performed by an ultrasound assisted technique and the correct catheter position was verified by standard chest X-rays.

The average blood flowrates were 250 ml/min, and the mean KT/V calculated in all patients one month after the beginning of the dialytic therapy was 1.09 ± 0.02. In six patients the catheter was utilized for at least 4 months, in one patient for 8 months. The devices were easily removed when the patient's AVF was functional and usable.

We found that the use of the Ash Split Cath as a temporary, prolonged vascular access in uremic patients was optimal allowing for flexibility in organizing the dialysis treatment schedule and in yielding a good performance in the initial dialysis therapy. Moreover, this device allows, in these patients, a satisfactory dialysis efficiency.

Cystic pancreatic tumors: should we resect all of them?

OBJECTIVE

Pancreatic cystic tumors are relatively rare tumors and only 1% of them are malignant. They are often asymptomatic and detected as incidental findings through diagnostic imaging. Currently there are no universal guide lines for the correct clinical approach to pancreatic cystic lesions. Cross-sectional imaging demonstrates some typical morphological features that determine the pre-operative diagnosis of the pancreatic cystic lesions (serous or mucinous cystadenoma, intraductal papillary mucinous neoplasms). In addition, endoscopic ultrasonography permits the collection and analysis of the fluid content. The aim of this paper is to describe our case load in the management of pancreatic cystic neoplasms and propose some criteria for choosing between surgical or conservative approaches.

PATIENTS AND METHODS

12 patients with pancreatic cystic neoplasms were retrospectively evaluated. They were studied using cross-sectional imaging modalities (computed tomography and magnetic resonance); endoscopic ultrasonography was performed in 7 patients.

RESULTS

In each patient a careful evaluation of several factors (age, comorbidity, imaging features, symptoms, life expectancy) conditioned our clinical decision. Among our 12 patients, surgical resection was performed in 7 cases.

DISCUSSION

The treatment of pancreatic cystic lesions is still a dilemma because even in the presence of malignant potential, pancreatic surgery remains very complicated and demolitive. Many factors need to be considered in the management of cystic pancreatic tumors. The most important include histological type, location, size, age and clinical condition of the patient.

CONCLUSIONS

A correct multidisciplinary pre-operative diagnosis is mandatory. Surgery should only be performed in selected cases.

Laparoscopic resection of an abdominal wall desmoid using a modified suture traction technique: the “marionette trick”

Desmoids are rare mesenchimal tumors that may originate also inside the abdomen or in the abdominal wall. These tumors are biologically characterized by a tendency to local growth, and only rarely are they able to develop distant metastases. Surgical excision usually is the best treatment with a chance of a cure. In the few reports on intraabdominal or abdominal wall desmoids, open surgery always was performed. The first case of successful laparoscopic resection of a symptomatic anterior wall desmoid tumor with intraabdominal growth is reported. During the procedure, it was difficult to mobilize and grasp the mass using the common laparoscopic instruments, but with the help of the "marionette trick," modified suture traction technique, the tumor could be removed easily using only three trocars. With four traction sutures minimizing the wall trauma, the trick made it possible to mobilize the mass in at least, seven directions, according to the principles of physical forces and vectors. This simple trick can be helpful for other common laparoscopic procedures, avoiding the insertion of sometimes ineffective instruments through more traumatic trocars.

Effects of different doses in continuous veno-venous haemofiltration on outcomes of acute renal failure: a prospective randomised trial

BACKGROUND

Continuous veno-venous haemofiltration is increasingly used to treat acute renal failure in critically ill patients, but a clear definition of an adequate treatment dose has not been established. We undertook a prospective randomised study of the impact of different ultrafiltration doses in continuous renal replacement therapy on survival.

METHODS

We enrolled 425 patients, with a mean age of 61 years, in intensive care who had acute renal failure. Patients were randomly assigned ultrafiltration at 20 ml/h-1/kg(-1) (group 1, n = 146), 35 ml/h(-1)/kg(-1) (group 2, n = 139), or 45 ml/h(-1)/ kg(-1) (group 3, n = 140). The primary endpoint was survival at 15 days after stopping haemofiltration. We also assessed recovery of renal function and frequency of complications during treatment. Analysis was by intention to treat.

RESULTS

Survival in group 1 was significantly lower than in groups 2 (p = 0.0007) and 3 (p = 0.0013). Survival in groups 2 and 3 did not differ significantly (p = 0.87). Adjustment for possible confounding factors did not change the pattern of differences among the groups. Survivors in all groups had lower concentrations of blood urea nitrogen before continuous haemofiltration was started than non-survivors. 95%, 92% and 90% of survivors in groups 1, 2 and 3, respectively, had full recovery of renal function. The frequency of complications was similarly low in all groups.

INTERPRETATION

Mortality among these critically ill patients was high, but increase in the rate of ultrafiltration improved survival significantly We recommend that ultrafiltration should be prescribed according to patient's bodyweight and should reach at least 35 ml/h(-1)/kg(-1).

Efficacy and safety of elective laparoscopic cholecystectomy in elderly: a case-controlled comparison with the open approach

BACKGROUND

Minimally invasive laparoscopic surgery is the method of choice for the surgical treatment of gallbladder disease. However, surgery of the biliary tract in the elderly is often associated with high morbidity and mortality.

PATIENTS AND METHOD

To evaluate the efficacy and safety of the laparoscopic cholecystectomy in the elderly with symptomatic, uncomplicated gallbladder disease, we retrospectively compared the records of 24 consecutive patients over 70 years of age with symptomatic uncomplicated gallbladder disease, who underwent elective laparoscopic cholecystectomy, with a similar cohort of patients who underwent elective open cholecystectomy for the same indications.

RESULTS

In the laparoscopic group we found a significantly low incidence of postoperative complications, low analgesics and antibiotics administration, rapid recovery, short length of stay and considerable cost savings.

CONCLUSION

We conclude that elective laparoscopic cholecystectomy in elderly with uncomplicated gallbladder disease is safe and effective and we suggest that it may become the surgical procedure of choice.

TINU syndrome associated with reduced complement levels

The TINU syndrome (tubulointerstitial nephritis and uveitis) was first described by Dobrin et al. in 1975. Since then, more than 50 cases have been documented each with diverse immunopathogenetic and genetic characteristics. The aim of this report is to describe a case of TINU associated with reduced complement levels. We profile a 48-year-old white female with persistently reduced C4 complement levels during the acute phase of the pathology and with an unaltered immunologic profile. Renal biopsy evidenced a significant lymphocytic interstitial infiltration. Immunohistochemical studies of the interstitium infiltrates was positive for the presence of the T (CD3) markers (CD4 > CD8). Steroid therapy yielded a complete regression of the symptomatology with normalization of the complement levels. We suggest that it is possible to hypothesize that the various immunologic alterations associated with TINU, including the transient reduction complement levels, may be secondary to multiple inflammatory mechanisms which express themselves throughout the pathology.

Choosing new adsorbents for endogenous ultrapure infusion fluid: performances, safety and flow distribution

Adsorption may notably contribute to the removal of uremic toxins and to the efficiency of hemodialysis. We examined different uncoated stationary matrixes, charcoals and synthetic resins to establish their adsorptive capacities in relation to low (urea, creatinine) and high molecular weight (beta2-microglobulin, myoglobin) compounds in in vitro conditions (steady state and flow-through) using isotonic solutions or uremic ultrafiltrate. Trace metal, particle release analyses and scanning electron microscopy of different adsorbents were performed. Dynamic flow-distribution studies were made using 99Technetium and analysing the different regions of interest by single head gamma-camera. We show that adsorbents may differ greatly as to their adsorptive capacity depending on flow rate, nature, and total mass of the compounds to be removed from the ultrafiltrate. These studies suggest a methodological approach for screening stationary matrixes for possible application in hemodialysis.

Chronic liver herniation through a right Bochdalek hernia with acute onset in adulthood

Congenital right diaphragmatic hernia of Bochdalek rarely occurs in adults and usually is asymptomatic. We report a right Bochdalek hernia with chronic liver herniation and intestinal malrotation in a 55-year old woman who presented with acute intestinal occlusion. The diagnosis required definitive confirmation by CT scan. With impending strangulation, emergency surgery through a thoracoabdominal approach resulted in an easy hernia repair and reduced the technical difficulties due to the intestinal malrotation.

Continuous urea monitoring in hemodialysis: a model approach to forecast dialytic performance. Results of a multicenter study

BACKGROUND

A urea biosensor, inserted into the ultrafiltrate collection-line of paired filtration dialysis (PFD), not only allows on-line dialysis quantification, but also forecasts final (Cend) and 30 min equilibrated urea concentration (Ceq), the most reliable value for calculating dialysis efficiency. The urea biosensor processes plasma ultrafiltrate continuously, delivering a large amount of data to the computer, which estimates the parameters by a mathematical model, thus predicting the whole urea profile with rebound.

METHODS

A multicenter randomized trial on 41 patients was conducted to ascertain the ability of a two-pool variable-volume urea model to forecast Cend and Ceq at 60 and 90 min after the start of dialysis. Two alternative dialytic treatments, A or B, were chosen, the latter being more efficient. Each treatment included six serial PFD. The accuracy of forecasting was evaluated through four indices based on forecast errors, calculated as the difference between observed and forecasted urea values: mean percent error (MPE) (%), mean absolute deviation (MAD) (mg/dl), mean absolute percent error (MAPE) (%) and root mean squared error (RMSE) (mg/dl).

RESULTS

Forecasted urea concentrations were lower than those measured by the biosensor. MPE for Cend was negligible in A (+1.2%) and much higher in B (+7.2%); both values improved at 90 min, +1.0% and +5.8%, respectively. MAD for Cend was similar in both treatments and improved slightly at 90 min, ranging from 4.9 to 5.9 mg/dl. MPE for Ceq was +4% in A and and more than doubled in B (+11.5%); both values improved at 90 min, +3.7% and +9.7%, respectively. MAD for Ceq was 7.5 mg/dl in A and 8.5 mg/dl in B; both improved at 90 min, 6.7 and 7.4 m g/dl, respectively. The other indices, MAPE and RMSE, showed similar results. Comparison between the errors of the two treatments with analysis of variance (ANOVA) for repeated measures gave no significant results.

CONCLUSIONS

Our model forecasts of urea concentrations were overall lower than the measured ones: the bias was negligible for A-Cend, greater for the A-Ceq and when the more efficient treatment B was used. The 60 min predictions improved at 90 min. The comparison between the prediction errors in the two treatments were not statistically significant. The recirculation measurement would probably reduce the bias if it were properly incorporated into the model.

Effectiveness of porto-intracaval shunt to reduce the negative effects of portal and caval clamping in the rabbit

In performing experimental liver surgery, it is difficult to prolong anhepatic time because the animals do not tolerate prolonged portal and caval clamping. To counteract prolonged venous stasis, the authors previously developed a simple porto-intracaval shunt. The shunt consists of a self-constructed inverted Y silicone tube. The effectiveness of this shunt was studied comparing two groups of 10 rabbits with shunt (S) versus those with clamped portal and inferior caval vein (C). In the group of rabbits that underwent porto-intracaval shunt, the results concerning intraoperative mortality, intraoperative increase in distal portal vein pressure, and incidence of the histologic signs of gut damage were clearly improved. The proposed porto-intracaval shunt was therefore effective in reducing some principal negative effects of portal and caval clamping. This type of porto-intracaval shunt can be therefore useful allowing improvement of experimental models concerning liver surgery in little animals.

Experimental anaesthesiologic protocol for porto-intracaval shunt for liver total vascular exclusion: preliminary study in the rabbit

The aim of this study was to evaluate the effects and interference of different anaesthetic techniques in rabbits undergoing liver total vascular exclusion using a porto-intracaval shunt. Twenty New Zealand rabbits were divided in three groups: group A receiving diazepam as premedication, ketamine + atropine for induction and maintenance of anaesthesia and undergoing a porto-intracaval shunt operation; group B receiving midazolam as premedication, ketamine + fentanyl + atropine for induction and maintenance of anaesthesia and undergoing a porto-intracaval shunt operation; group C receiving the same drugs as group B but undergoing a simple portal and caval clamping. The following parameters were studied: efficacy of premedication, vital parameters before and after clamping and insertion of the shunt, mean time to clamp and insert the shunt, mean survival time after clamping (group C) or activation of the shunt (groups A and B). Midazolam was significantly better for premedication; there was no statistically significant difference between groups A and B for the vital parameters, for the time necessary to clamp and insert the shunt, for the intraoperative course, and for the mean survival time. The absence of a statistically significant difference between groups could be due to the low number of animals used in the study. There is actually evidence that a correct anaesthesiologic protocol, especially referring to analgesia and fluid management, improves the outcome of operated animals. Surely further studies, possibly conducted on a larger number of animals, are required to evaluate better the results observed and to consider applying these data and this experience to humans.