Effects of hyperoxemia in patients with sepsis - A post-hoc analysis of a multicentre randomized clinical trial.

BACKGROUND: Administration of supplemental oxygen is a life-saving treatment in critically ill patients. Still, optimal dosing remains unclear during sepsis. The aim of this post-hoc analysis was to assess the association between hyperoxemia and 90-day mortality in a large cohort of septic patients. METHODS: This is a post-hoc analysis of the Albumin Italian Outcome Sepsis (ALBIOS) randomized controlled trial (RCT). Patients with sepsis who survived the first 48 h since randomization were included and stratified into two groups according to their average PaO2 levels during the first 48 h (PaO2 0-48 h). The cut-off value was established at 100 mmHg (average PaO2 0-48 h >100 mmHg: hyperoxemia group; PaO2 0-48h≤100: normoxemia group). The primary outcome was 90-day mortality. RESULTS: 1632 patients were included in this analysis (661 patients in the hyperoxemia group, 971 patients in the normoxemia group). Concerning the primary outcome, 344 (35.4%) patients in the hyperoxemia group vs. 236 (35.7%) in the normoxemia group had died within 90 days from randomization (p = 0.909). No association was found after adjusting for confounders (HR 0.87; CI [95%] 0.736-1.028, p = 0.102) or after excluding patients with hypoxemia at enrollment, patients with lung infection or including post-surgical patients only. Conversely, we found an association between lower risk of 90-day mortality and hyperoxemia in the subgroup including patients who had the lung as primary site of infection (HR 0.72; CI [95%] 0.565-0.918). Mortality at 28 days, ICU mortality, incidence of acute kidney injury, use of renal replacement therapy, days to suspension of vasopressor or inotropic agents, and resolution of primary and secondary infections did not differ significantly. Duration of mechanical ventilation and length of stay in ICU were significantly longer in patients with hyperoxemia. CONCLUSIONS: In a post-hoc analysis of a RCT enrolling septic patients, hyperoxemia as average PaO2>100 mmHg during the first 48 h was not associated with patients' survival.

Hypertension in a cohort of obese Caucasian children and adolescents and its association with glycometabolic indices: A proposed screening tool.

BACKGROUND AND AIM: Hypertension (HTN) is common among obese children and adolescents and increases their cardiovascular risk later in adulthood. The aim of the study was to evaluate the prevalence of HTN identified by office blood pressure (BP) measurement and ambulatory BP monitoring (ABPM) in a cohort of obese children and adolescents and its association with anthropometric and glycometabolic indices. METHODS AND RESULTS: Seventy consecutive obese Caucasian children and adolescents aged 7-16 years were enrolled. Patients underwent ABPM, echocardiogram and carotid ultrasonography. Sex- and age-adjusted logistic multivariable analysis models were used to assess the association between HOMA-IR, HOMA-ß, QUICKI with HTN at ABPM. Receiver Operation Curve (ROC) analysis with Youden J statistics was used to identify the optimal HOMA-IR, HOMA-ß and QUICKI cut-off to predict HTN at ABPM. Hypertensive office BP was found in 25.7% of obese patients. ABPM diagnosed HTN in 34.9% of patients: 20.6% of obese patients had masked HTN (MHTN), and 12.7% had white coat HTN (WCH). Hypertensive obese patients (according to ABPM) had higher HOMA-IR and HOMA-ß, and a lower QUICKI than normotensive subjects. HOMA-IR, HOMA-ß and QUICKI predicted HTN at ABPM in obese patients in age- and sex-adjusted logistic multivariable models. Optimal cut-offs to predict HTN at ABPM in obese patients were: HOMA-IR ≥ 3.30, HOMA-ß ≥ 226.7 and QUICKI <0.33, with high sensitivity. CONCLUSIONS: A sequential testing strategy applying office BP and glycometabolic indices can identify hypertensive obese pediatric patients with high diagnostic accuracy and potentially reducing costs. This strategy needs validation in an external and larger cohort.

Advances in pharmacotherapy for cardiac amyloidosis.

INTRODUCTION: Amyloidosis is a group of progressive and devastating disorders resulting from extracellular deposition of misfolded proteins into tissues. When deposition of fibrils occurs in cardiac tissues, this systemic disease can lead to a very poor prognosis. Systemic amyloidosis can be acquired [light chain (AL) amyloidosis; AA amyloidosis], or hereditary [transthyretin (ATTR) amyloidosis]. Cardiac disease in amyloidosis is usually secondary to a systemic disease. The diagnosis of cardiac involvement is often delayed and yields an adverse prognosis. AREAS COVERED: in this review, the authors report current literature on advances in pharmacotherapy for cardiac amyloidosis, mainly focused on AL and ATTR amyloidosis treatment. EXPERT OPINION: Most pharmacological trials in amyloidosis patients, both AL and TTR, are directed to study the effects of drugs on polyneuropathy. However, since cardiac involvement carries a prominent negative survival impact in amyloidosis patients, future research should be more focused on amyloidosis cardiomyopathy as primary endpoint. Additionally, in AL amyloidosis therapies are mainly derived from experience on multiple myeloma treatment. In this specific setting, possible future research could particularly focus on immunotherapeutic agents able to optimize the standard chemotherapy results and, thus, allowing a larger population of patients to be treated by bone marrow stem cell transplantation.

Unraveling the role of mechanical stimulation on smooth muscle cells: A comparative study between 2D and 3D models.

A thorough understanding of cell response to combined culture configuration and mechanical cues is of paramount importance in vascular tissue engineering applications. Herein, we investigated and compared the response of vascular smooth muscle cells (vSMCs) cultured in different culture environments (2D cell monolayers and 3D cellularized collagen-based gels) in combination with mechanical stimulation (7% uniaxial cyclic strain, 1 Hz) for 2 and 5 days. When cyclic strain was applied, two different responses, in terms of cell orientation and expression of contractile-phenotype proteins, were observed in 2D and 3D models. Specifically, in 2D configuration, cyclic strain caused ∼50% of cell population to align nearly perpendicular (80-90 degrees) to the strain direction, while not influencing the contractile-phenotype protein expression, as compared to the 2D static controls. Conversely, the application of uniaxial strain to 3D constructs induced a ∼60% cell alignment almost parallel (0-10 degrees) to the strain direction. Moreover, 3D mechanical stimulation applied for 5 days induced a twofold increase of SM α-actin level and a 14-fold increase of calponin expression as compared to 3D static controls. Altogether these findings provide a new insight into the potential to drive cell behavior by modulating the extracellular matrix and the biomechanical environment. Biotechnol. Bioeng. 2016;113: 2254-2263. © 2016 Wiley Periodicals, Inc.

A dynamic distention protocol for whole-organ bladder decellularization: histological and biomechanical characterization of the acellular matrix.

A combined physical-chemical protocol for whole full-thickness bladder decellularization is proposed, based on organ cyclic distention through repeated infusion/withdrawal of the decellularization agents through the urethra. The dynamic decellularization was intended to enhance cell removal efficiency, facilitating the delivery of detergents within the inner layers of the tissue and the removal of cell debris. The use of mild chemical detergents (hypotonic solution and non-ionic detergent) was employed to limit adverse effects upon matrix 3D ultrastructure. Inspection of the presence of residual DNA and RNA was carried out on decellularized matrices to verify effective cell removal. Histological investigation was focused on assessing the retention of adequate structural and functional components that regulate the biomechanical behaviour of the acellular tissue. Biomechanical properties were evaluated through uniaxial tensile loading tests of tissue strips and through ex vivo filling cystometry to evaluate the whole-organ mechanical response to a physiological-like loading state. According to our results, a dynamic decellularization protocol of 17 h duration with a 5 ml/min detergent infusion flow rate revealed higher DNA removal efficiency than standard static decellularization, resulting in residual DNA content < 50 ng/mg dry tissue weight. Furthermore, the collagen network and elastic fibres distribution were preserved in the acellular ECM, which exhibited suitable biomechanical properties in the perspective of its future use as an implant for bladder augmentation.

Spermatogenesis in Hodgkin's lymphoma patients: a retrospective study of semen quality before and after different chemotherapy regimens.

STUDY QUESTION: Is spermatogenesis impairment caused by Hodgkin's lymphoma (HL) itself or by the various treatments? SUMMARY ANSWER: HL is not itself the main cause of impaired spermatogenesis, which is instead affected by the treatment; the extent of impairment depends on the type of treatment and the number of cycles. WHAT IS KNOWN ALREADY: Data in the literature are contradictory, although most studies found poor semen quality in HL patients prior to treatment. The impact of therapy on spermatogenesis depends on the type of treatment, but the time needed to recover testicular function following treatment with chemotherapeutic agents inducing azoospermia is unknown. STUDY DESIGN, SIZE, DURATION: In a retrospective study, the semen parameters of 519 patients (504 with sperm and 15 who were azoospermic) were investigated.HL patients were analysed before therapy. A longitudinal study was also conducted of semen quality in 202 patients pre- and post-ABVD (doxorubicin, bleomycin, vinblastine and dacarbazine) at T0 (baseline) and 6 (T6), 12 (T12) and 24 (T24) months after the end of treatment, and of 42 patients pre- and post-BEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, prednisone), COPP/ABVD (cyclophosphamide, vincristine, procarbazine, prednisone, doxorubicin, bleomycin, vinblastine and dacarbazine), OPP/ABVD (vincristine, procarbazine, prednisone, doxorubicin, bleomycin, vinblastine and dacarbazine) or MOPP (mechlorethamine, vincristine, procarbazine and prednisone) and inguinal radiotherapy at different observation times (from T0 to 16 years after treatment). PARTICIPANTS/MATERIALS, SETTING, METHODS: Semen parameters were examined according to World Health Organization 2010 criteria, evaluating sperm concentration, total sperm number, progressive motility and morphology. MAIN RESULTS AND THE ROLE OF CHANCE: Our data, which pertain to the largest caseload reported to date, indicate that 75% of HL patients are normozoospermic prior to treatment. The results from the HL patients studied pre- and post-therapy demonstrate that spermatogenesis recovery depends on the therapeutic regimen used. After ABVD, there was a statistically significant decrease in sperm concentration and total sperm number at T6 and T12 (P < 0.001; P < 0.01, respectively). There was a significant drop in progressive motility (P < 0.001) and a significant increase in abnormal forms (P < 0.01) at T6. The differences in sperm concentration, total sperm number and abnormal forms at T0 and T24 were not statistically significant, indicating that sperm quality had returned to pre-therapy values. The most interesting data in terms of patient management arise from the study of azoospermia induced by other chemotherapeutic agents. A high number of BEACOPP, COPP/ABVD, OPP/ABVD or MOPP cycles (≥6) induced a permanent absence of sperm in the seminal fluid, while even following a low number of cycles (<6), spermatogenesis only recovered after 3-5 years and semen quality was highly impaired. LIMITATIONS, REASONS FOR CAUTION: The study type (retrospective) and the low caseload and varying time of the follow-up do not permit any firm conclusions to be drawn about the recovery of spermatogenesis after BEACOPP or other combined therapies, or the identification of any risk factors for testicular function in treated patients. WIDER IMPLICATIONS OF THE FINDINGS: The pretreatment semen parameters of HL patients in this study were better than some results reported in the literature, with a higher percentage of normozoospermic patients. Strengths of this study were the large caseload of HL patients and a high degree of consistency in semen analysis, as all parameters were assessed in the same laboratory. Following the azoospermia induced by different chemotherapeutic protocols, spermatogenesis may take several years to recover. Awareness of this issue will enable oncologists to better inform patients about the possibility of recovering fertility post-treatment and also demonstrates the importance of semen cryobanking before beginning any cancer treatment. STUDY FUNDING/COMPETING INTERESTS: Supported by a grant from the Italian Ministry of Education and Research (MIUR-PRIN) and the University of Rome 'La Sapienza' Faculty of Medicine. The authors have no conflicts of interest.

A novel passive left heart platform for device testing and research.

Integration of biological samples into in vitro mock loops is fundamental to simulate real device's operating conditions. We developed an in vitro platform capable of simulating the pumping function of the heart through the external pressurization of the ventricle. The system consists of a fluid-filled chamber, in which the ventricles are housed and sealed to exclude the atria from external loads. The chamber is connected to a pump that drives the motion of the ventricular walls. The aorta is connected to a systemic impedance simulator, and the left atrium to an adjustable preload. The platform reproduced physiologic hemodynamics, i.e. aortic pressures of 120/80 mmHg with 5 L/min of cardiac output, and allowed for intracardiac endoscopy. A pilot study with a left ventricular assist device (LVAD) was also performed. The LVAD was connected to the heart to investigate aortic valve functioning at different levels of support. Results were consistent with the literature, and high speed video recordings of the aortic valve allowed for the visualization of the transition between a fully opening valve and a permanently closed configuration. In conclusion, the system showed to be an effective tool for the hemodynamic assessment of devices, the simulation of surgical or transcatheter procedures and for visualization studies.

Electrical conditioning of adipose-derived stem cells in a multi-chamber culture platform.

In tissue engineering, several factors play key roles in providing adequate stimuli for cells differentiation, in particular biochemical and physical stimuli, which try to mimic the physiological microenvironments. Since electrical stimuli are important in the developing heart, we have developed an easy-to-use, cost-effective cell culture platform, able to provide controlled electrical stimulation aimed at investigating the influence of the electric field in the stem cell differentiation process. This bioreactor consists of an electrical stimulator and 12 independent, petri-like culture chambers and a 3-D computational model was used to characterize the distribution and the intensity of the electric field generated in the cell culture volume. We explored the effects of monophasic and biphasic square wave pulse stimulation on a mouse adipose-derived stem cell line (m17.ASC) comparing cell viability, proliferation, protein, and gene expression. Both monophasic (8 V, 2 ms, 1 Hz) and biphasic (+4 V, 1 ms and -4 V, 1 ms; 1 Hz) stimulation were compatible with cell survival and proliferation. Biphasic stimulation induced the expression of Connexin 43, which was found to localize also at the cell membrane, which is its recognized functional mediating intercellular electrical coupling. Electrically stimulated cells showed an induced transcriptional profile more closely related to that of neonatal cadiomyocytes, particularly for biphasic stimulation. The developed platform thus allowed to set-up precise conditions to drive adult stem cells toward a myocardial phenotype solely by physical stimuli, in the absence of exogenously added expensive bioactive molecules, and can thus represent a valuable tool for translational applications for heart tissue engineering and regeneration.

In vitro study of the aortic interleaflet triangle reshaping.

Aortic interleaflet triangle reshaping (AITR) is a surgical approach to aortic valve incontinence that involves placing three stitches at half of the interleaflet triangles height. In this work, the relationship between the actual stitch height and valve functioning, and the safety margin that the surgeon can rely on in applying the stitches were systematically investigated in vitro. AITR surgery was applied to six swine aortic roots placing the stitches empirically at 50%, 60% and 75% of the triangle heights. Then the actual stitch heights were measured and the hydrodynamic performances were evaluated with a pulsatile hydrodynamic mock loop. Actual stitch heights were 45±2%, 61±4% and 79±6%. As compared to untreated conditions, the 50% configuration induced a significant variation in the effective orifice area. With stitches placed at 60%, the mean systolic pressure drop increased significantly with respect to the untreated case, but no significant changes were recorded with respect to the 50% configuration. At 75%, all the hydrodynamic parameters of systolic valve functioning worsened significantly. Summarizing, the AITR technique, when performed in a conservative manner did not induce significant alterations in the hydrodynamics of the aortic root in vitro, while more aggressive configurations did. The absence of a statistically significant difference between the 50% and 60% configurations suggests that there is a reasonably limited risk of inducing valve stenosis in the post-op scenario due to stitch misplacement.

Epidemiology and outcome of sepsis syndromes in Italian ICUs: a muticentre, observational cohort study in the region of Piedmont.

BACKGROUND: Sepsis is an important cause of mortality and morbidity in the intensive care unit (ICU). We performed a study to describe the epidemiology of sepsis syndromes in patients admitted to ICUs of the Piedmont region. METHODS: In this prospective, multicentre, observational study, all 3902 patients admitted to a network of 24 ICUs from 17 hospitals during a 180 day period (April 3-September 29, 2006) were included. Patients were followed from the first day of admission until death or ICU discharge. RESULTS: The incidence of sepsis during the ICU stay was 11.4% (N.=446), corresponding to an incidence of 25 cases/100,000 inhabitants/year; 141 (31.6%) patients had only sepsis, 160 patients had severe sepsis (35.9%) and 145 patients (32.5%) had septic shock In 227 patients (50.9%), sepsis was observed within 48 hours after admission to the ICU, and 219 patients (49.1%) developed ICU-acquired sepsis. The main sources of infection were the lungs, abdomen, and urinary tract. ICU mortality was higher (41.3 vs. 17.3%, P<0.0001) and the median ICU length of stay longer (15 vs. 2 days, P<0.0001) in patients with sepsis than in those without sepsis. The mortality rate increased with the severity of sepsis. ICU-acquired sepsis was associated with higher ICU mortality rates than sepsis occurring within 48 hours of ICU admission (49.8 vs. 33.0%, P<0.0001). CONCLUSION: Sepsis is a common occurrence in critically ill patients. Our data underscore the regional variability in the epidemiology and outcome of sepsis syndromes and may be useful to guide appropriate resource allocation.

An experimental approach to identify dynamical models of transcriptional regulation in living cells.

We describe an innovative experimental approach, and a proof of principle investigation, for the application of System Identification techniques to derive quantitative dynamical models of transcriptional regulation in living cells. Specifically, we constructed an experimental platform for System Identification based on a microfluidic device, a time-lapse microscope, and a set of automated syringes all controlled by a computer. The platform allows delivering a time-varying concentration of any molecule of interest to the cells trapped in the microfluidics device (input) and real-time monitoring of a fluorescent reporter protein (output) at a high sampling rate. We tested this platform on the GAL1 promoter in the yeast Saccharomyces cerevisiae driving expression of a green fluorescent protein (Gfp) fused to the GAL1 gene. We demonstrated that the System Identification platform enables accurate measurements of the input (sugars concentrations in the medium) and output (Gfp fluorescence intensity) signals, thus making it possible to apply System Identification techniques to obtain a quantitative dynamical model of the promoter. We explored and compared linear and nonlinear model structures in order to select the most appropriate to derive a quantitative model of the promoter dynamics. Our platform can be used to quickly obtain quantitative models of eukaryotic promoters, currently a complex and time-consuming process.

A novel environmental chamber for neuronal network multisite recordings.

Environmental stability is a critical issue for neuronal networks in vitro. Hence, the ability to control the physical and chemical environment of cell cultures during electrophysiological measurements is an important requirement in the experimental design. In this work, we describe the development and the experimental verification of a closed chamber for multisite electrophysiology and optical monitoring. The chamber provides stable temperature, pH and humidity and guarantees cell viability comparable to standard incubators. Besides, it integrates the electronics for long-term neuronal activity recording. The system is portable and adaptable for multiple network housings, which allows performing parallel experiments in the same environment. Our results show that this device can be a solution for long-term electrophysiology, for dual network experiments and for coupled optical and electrical measurements.

In vitro hemodynamics and valve imaging in passive beating hearts.

Due to their high complexity, surgical approaches to valve repair may benefit from the use of in vitro simulators both for training and for the investigation of those measures which can lead to better clinical results. In vitro tests are intrinsically more effective when all the anatomical substructures of the valvular complexes are preserved. In this work, a mock apparatus able to house an entire explanted porcine heart and subject it to pulsatile fluid-dynamic conditions was developed, in order to enable the hemodynamic analysis of simulated surgical procedures and the imaging of the valvular structures. The mock loop's hydrodynamic design was based on an ad-hoc defined lumped-parameter model. The left ventricle of an entire swine heart was dynamically pressurized by an external computer-controlled pulse duplicator. The ascending aorta was connected to a hydraulic circuit which simulated the input impedance of the systemic circulation; a reservoir passively filled the left atrium. Accesses for endoscopic imaging were located in the apex of the left ventricle and in the aortic root. The experimental pressure and flow tracings were comparable with the typical in vivo curves; a mean flow of 3.5±0.1l pm and a mean arterial pressure of 101±2 mmHg was obtained. High-quality echographic and endoscopic video recordings demonstrated the system's excellent potential in the observation of the cardiac structures dynamics. The proposed mock loop represents a suitable in vitro system for the testing of minimally-invasive cardiovascular devices and surgical procedures for heart valve repair.

Nonsurgical treatment of Dupuytren's contracture: 1-year US post-marketing safety data for collagenase clostridium histolyticum.

BACKGROUND: Collagenase clostridium histolyticum (CCH) is a Food and Drug Administration-approved treatment for adult patients with Dupuytren's contracture with a palpable cord that has been shown efficacious and safe in clinical trials. METHODS: This paper summarizes the most common post-marketing clinical adverse event (AE) reports received by the manufacturer of CCH and sponsor of the US Biologics License Application (Auxilium Pharmaceuticals, Malvern, PA, USA) during the first 12 months after drug approval and commercialization in the USA. RESULTS: Of the 115 AE reports describing 270 AEs voluntarily received from patients or health care providers after approximately 5,400 injections of CCH administered, the most common AEs involved local, nonserious reactions to treatment, including skin tears, peripheral edema, and contusion. There were few serious AEs observed (0.6% reporting rate per 1,000 injections), and two flexor tendon ruptures and one flexor pulley injury were reported. CONCLUSIONS: Analysis of post-marketing AEs received for CCH in the first year post-approval supports the safety profile reported earlier during clinical development and did not reveal additional clinical risks or concerns about CCH.

In vitro study of aortic valves treated with neo-chordae grafts: hydrodynamics and tensile force measurements.

Reparative surgery of the aortic root functional unit (ARFU) allows for a better preservation of the functionality of the native structure compared to prosthesis implantation. Post-operative results are satisfactory, whereas mid- and long-term results are challenging, for example in terms of cusps prolapse recurrence. At the Cardiothoracic Surgery Unit of the Sacco Hospital, a new surgical technique aimed at the stabilization in time of the results of standard ARFU repair operations has been applied. This technique, inspired by the mitral neo-chordae (NC) implantation, consists of implanting an e-PTFE suture thread between the prolapsed cusp and the sinotubular junction. Aim of this study was to assess the influence of NC implantation on the ARFU functioning by evaluating with an owned pulsatile in vitro apparatus the force magnitude acting on the NC and the dynamic behavior of porcine ARFUs treated according to the operating-room procedures. The maximum recorded values of the mean and peak diastolic forces were 0.064 and 0.186 N, respectively, and were linearly dependent upon the mean diastolic pressure across the valve. In addition, the measurements of the opening-closing times and valve leakage volumes, performed at pre- and post-surgeries, yielded that the valve functionality was not significantly influenced by NC implantation.

Ultrasoundelastography: Can it provide valid information for differentiation of benign and malignant thyroid nodules?

Ultrasoundelastography (USE) is a new imaging technique that is performed with a normal ultrasound transducer. It provides improved characterization of a tissue or nodule based on the latter's elasticity and stiffness. The aim of the present, prospective study was to assess the validity of USE in characterizing thyroid nodules. USE patterns were analyzed in light of nodule cytology (British Thyroid Association classification) to determine whether these patterns can be used to decide whether or not fine-needle aspiration cytology (FNAC) is indicated. We examined a consecutive series of 617 thyroid nodules in patients referred for the first time to the Endocrinology Unit of Atri Hospital (Atri, [TE]). Patients underwent ultrasonographic and USE examinations of their thyroid nodules, which were then subjected to FNAC. All nodules with Thy 1 cytology were excluded, leaving 567 nodules for analysis. USE findings were classified on the basis of the degree and distribution of elasticity within the lesion: four patterns were identified (1, 2, 3a, 3b, or 4).None of the nodules with Thy 4 cytology (malignant) had USE pattern 1 or 2; patterns 3 and 4 were associated with higher cytologic grades. In conclusion, USE provides additional information on thyroid nodules, which can be used with ultrasound features of the nodules, to decide whether FNAC is indicated. In fact, patterns 1 and 2 do not seem to be associated with Thy 4 cytology.

Conversion of spinal anesthesia into general anesthesia: an evaluation of more than 35,000 spinal anesthetics.

BACKGROUND: The aim of this study was to evaluate the number of conversions from spinal anesthesia (SA) into general anesthesia (GA) in a large number of patients who underwent surgery over a period of twenty-one years. METHODS: From the hospital's database, all surgical procedures performed under SA between January 1, 1988 and December 31, 2008 were retrieved. From this file, all SA cases converted into GA cases requiring endotracheal intubation were selected. Patients were divided in four groups, according to the reason for GA: IMPOSS (SA impossible to perform), FAIL (SA non profound enough for allowing surgery, even with light sedation), INSUFF (SA inadequate for unexpected prolonged duration of surgery), and COMPL (occurrence of complications associated with SA and requiring rapid control of ventilation). Anesthesiologists who performed SA were divided according their experience. The outcomes of patients converted to GA were compared with a matched sample of patients who received planned GA. RESULTS: A total of 35,960 SA cases were performed from 1988 to 2008; 29,220 and 6,740 SA cases were for elective and emergency surgery, respectively. Two hundred seventeen (0.6%) SA cases were converted into GA cases; 80.2% and 19.8% of the conversions were recorded in elective and emergency operations, respectively, with obstetric operations being the most prevalent (82/217). The primary reasons for the conversions, in a rank order, were INSUFF 107 (49.3%), FAIL 84 (38.7%), IMPOSS 13 (5.9%), and COMPL 13 (5.9%). Complications more frequently occurred in the aged population (P<0.05). Anesthesiologists with less experience had higher percentages of FAIL, IMPOSS, INSUFF, and COMPL SA cases in comparison with experienced anesthesiologists (odd ratios being 4.7, 3.0, 2.4, and 4.4, respectively). There was no difference in the frequency of complications compared to a matched sample of 1,000 patients who underwent GA (P=0.65). CONCLUSION: SA has been found to be a safe and highly effective technique. Failure of SA was infrequent in a large number of patients surveyed and most often occurred with less experienced anesthesiologists. Conversion to GA did not produced different outcomes in comparison with planned GA. Prospective studies with a definite protocol for recording data performed on a large number of patients may help in determining the factors associated with conversion from SA into GA and how to avoid these unexpected situations.

Mechanisms of polymyxin B endotoxin removal from extracorporeal blood flow: molecular interactions.

The outer leaflet of Gram-negative bacteria membrane contains a great amount of lipopolysaccharides, also known as endotoxins, which play a central role in the pathogenesis of septic shock. It has been demonstrated that the polymyxin B (PMB) molecule has both antibacterial and antiendotoxin capabilities; in fact, it is able to compromise the bacterial outer membrane and bind lipopolysaccharides, thereby neutralizing its toxic effects. Extracorporeal hemoperfusion treatments based on cartridges containing PMB-immobilized fibers (Toraymyxin PMX-F; Toray Industries, Tokyo, Japan) are used to remove endotoxins circulating in the blood flow. In this study, we focused on the characterization of the interactions occurring in the formation of the PMB-endotoxin complex at the molecular level. In particular, the molecular mechanics approach was used to evaluate the interaction energy and eventually the interaction force between the two molecules. PMB was faced with five molecular portions of lipopolysaccharides differing in their structure. The interaction energy occurring for each molecular complex was calculated at different intermolecular distances and the binding forces were estimated by fitting interaction energy data. Results show that the short-range interactions between PMB and endotoxins are mediated mainly by hydrophobic forces, while in the long term, the complex formation is driven by ionic forces only. Maximum binding forces calculated via molecular mechanics for the PMB-endotoxin complex are in the range of 1.39-3.79 nN. Understanding the interaction mechanism of the single molecular complex is useful both in order to figure out the molecular features of such interaction and to perform higher scale level analysis, where such nanoscale detail is impractical but could be used to account for molecular behavior at a coarse level of discretization.

Mechanisms of polymyxin B endotoxin removal from extracorporeal blood flow: hydrodynamics of sorption.

The removal of blood endotoxins with the Toraymyxin extracorporeal sorption device exploits the capability of immobilized polymyxin B (PMB) to bind endotoxins stably with a high specificity. Although adsorption is a molecular-scale mechanism, it involves hydrodynamic phenomena in the whole range from the macroscopic down to the supramolecular scales. In this paper we summarize our experience with a computational, multiscale investigation of this device's hydrodynamic functionality. 3D computational fluid dynamics models were developed for the upper-scale studies. The flow behavior in the sorbent material was either modeled as a homogeneous Darcy's flow (macroscale study), or described as the flow through realistic geometrical models of its knitted fibers (mesoscale study). In the microscale study, simplified 2D models were used to track the motion of modeled endotoxin particles subjected to the competition of flow drag and molecular attraction by the fiber-grafted PMB. The results at each scale level supplied worst-case input data for the subsequent study. The macroscale results supplied the peak velocity of the flow field that develops in the sorbent. This was used in the mesoscale analysis, yielding a realistic range for the shear stresses in the fluid next to the fiber surface. With wall shear stresses in this range, endotoxin particle tracking was studied both in the vicinity of a single immobilized PMB molecule, and in the presence of a layer of PMB molecules evenly distributed at the fiber surface. Results showed that the capability to seize endotoxin molecules extends at least at a distance of 10-20 nm from the surface, which is one order of magnitude greater than the stable intermolecular bond characteristic distance. We conclude that a multiscale approach has the power to provide a comprehensive understanding, shedding light both upon the physics involved at each scale level and the mutual interactions of phenomena occurring at different scales.