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This paper analyzes the scalability in arrayed waveguide grating router (AWGR)-based interconnect architectures and demonstrates active AWGR-based switching using a distributed control plane. First, the paper analyses an all-to-all single AWGR passive interconnection with $N$ nodes and proposes a new architecture that overcomes the scalability limitation given by wavelength registration and crosstalk, by introducing multiples of smaller AWGRs $(W$ × $W)$ operating on a fewer number of wavelengths $(W < N)$. Second, this paper demonstrates active AWGR switching with a distributed control plane, to be used when the size of the interconnection network makes the all-to-all approach using passive AWGRs impractical. In particular, an active AWGR-based TONAK switch is introduced. TONAK combines an all-optical NACK technique, which removes the need for electrical buffers at the switch input/output ports, and a TOKEN technique, which enables a distributed all-optical arbiter to handle packet contention. The experimental validation and performance study of the AWGR-based TONAK switch is presented, demonstrating the feasibility of the TONAK solution and the high throughput and low average packet latency for an up to 75% offered load. © 2013 IEEE.

This paper analyzes the scalability in arrayed waveguide grating router (AWGR)-based interconnect architectures and demonstrates active AWGR-based switching using a distributed control plane. First, the paper analyses an all-to-all single AWGR passive interconnection with $N$ nodes and proposes a new architecture that overcomes the scalability limitation given by wavelength registration and crosstalk, by introducing multiples of smaller AWGRs $(W$ × $W)$ operating on a fewer number of wavelengths $(W < N)$. Second, this paper demonstrates active AWGR switching with a distributed control plane, to be used when the size of the interconnection network makes the all-to-all approach using passive AWGRs impractical. In particular, an active AWGR-based TONAK switch is introduced. TONAK combines an all-optical NACK technique, which removes the need for electrical buffers at the switch input/output ports, and a TOKEN technique, which enables a distributed all-optical arbiter to handle packet contention. The experimental validation and performance study of the AWGR-based TONAK switch is presented, demonstrating the feasibility of the TONAK solution and the high throughput and low average packet latency for an up to 75% offered load. © 2013 IEEE.

The implantable cardioverter defibrillator (ICD) saves lives but clinical experience suggests that it may have detrimental effects on mental health. The ICD shock has been largely blamed as the main offender but empirical evidence is not consistent, perhaps because of methodological differences across studies.

INTRODUCTION: Cognitive impairment (CI) comprises a measurable deficit of different cognitive domains (memory, attention, problem solving, and motor speed), and has a high prevalence among congestive heart failure (CHF) patients. Only a few pilot studies have investigated the effects of cardiac resynchronization therapy (CRT) on cognitive performance. The purpose of this systematic review is to outline and evaluate results of published studies that assess the impact of CRT on neuropsychological function in CHF. METHODS: Electronic databases were searched for articles containing the following terms: CRT, cognition, cognitive, and neurocognitive. A data extraction was performed according to our objective from each study. Effect sizes were computed using Hedges' g. The within-group formula was used for cohort studies with a pre-post design, while the between-group formula was used for studies that compared independent groups. Multiple outcomes were combined in domain-specific synthetic scores as well as in a global score for each study, and a fixed-effect model was used to estimate the summary effects. RESULTS: Only three studies met criteria for inclusion in the analysis. The results of these studies were discordant and methodological limitations were identified. The meta-analysis of cognitive outcomes showed a nonsignificant overall effect (Hedges' g = 0.131, 95% confidence interval: -0.16 to 0.422), while the summary effects on executive functioning and attention reached statistical significance (Hedges' g = 0.374, 95% confidence interval: 0.085-0.662 and Hedges' g = 0.343, 95% confidence interval: 0.051-0.635, respectively). CONCLUSION: CI and related negative consequences have been largely documented in patients with heart failure but very few studies have assessed the plausible benefits of CRT on patients' cognitive function. Despite the statistical significance of the domain-specific pooled effects, their validity and clinical relevance is lacking due to methodo

Erythropoiesis is affected during deep saturation dives. The mechanism should be related to a downregulation of serum Erythropoietin (s-EPO) concentration or to a toxic effect of the hyperbaric hyperoxia. We evaluated s-EPO and other haematological parameters in 6 scuba divers before, during and after a 14-days guinness saturation dive (8-10 m). Athletes were breathing air at 1.8-2 ATA, under the control of a team of physicians. Serum parameters were measured before diving (T0) and: 7 days (T1), 14 days (T2) after the beginning of the dive and 2 h (T3) and 24 h (T4) after resurfacing. Hgb, and many other haematological parameters did not change whereas Ht, s-EPO, the ratio between s-EPO predicted and that observed and reticulocytes (absolute, percent) declined progressively from T0 to T3. At T4 a significant rise in s-EPO was observed. Hgb did not vary but erythropoiesis seemed to be affected as s-EPO and reticulocyte counts showed. All these changes were statistically significant. The experiment, conducted in realistic conditions of dive length, oxygen concentration and pressure, allows us to formulate some hypotheses about the role of prolonged hyperbarism on erythropoiesis. The s-EPO rise, 24 h after resurfacing, is clearly documented and related to the "Normobaric Oxygen Paradox". This evidence suggests interesting hypotheses for new clinical applications such as modulation of s-EPO production and Hgb content triggered by appropriate O2 administration in pre-surgical patients or in some anemic disease., JOURNAL ARTICLE, info:eu-repo/semantics/published

Erythropoiesis is affected during deep saturation dives. The mechanism should be related to a downregulation of serum Erythropoietin (s-EPO) concentration or to a toxic effect of the hyperbaric hyperoxia. We evaluated s-EPO and other haematological parameters in 6 scuba divers before, during and after a 14-days guinness saturation dive (8-10 m). Athletes were breathing air at 1.8-2 ATA, under the control of a team of physicians. Serum parameters were measured before diving (T0) and: 7 days (T1), 14 days (T2) after the beginning of the dive and 2 h (T3) and 24 h (T4) after resurfacing. Hgb, and many other haematological parameters did not change whereas Ht, s-EPO, the ratio between s-EPO predicted and that observed and reticulocytes (absolute, percent) declined progressively from T0 to T3. At T4 a significant rise in s-EPO was observed. Hgb did not vary but erythropoiesis seemed to be affected as s-EPO and reticulocyte counts showed. All these changes were statistically significant. The experiment, conducted in realistic conditions of dive length, oxygen concentration and pressure, allows us to formulate some hypotheses about the role of prolonged hyperbarism on erythropoiesis. The s-EPO rise, 24 h after resurfacing, is clearly documented and related to the "Normobaric Oxygen Paradox". This evidence suggests interesting hypotheses for new clinical applications such as modulation of s-EPO production and Hgb content triggered by appropriate O2 administration in pre-surgical patients or in some anemic disease., JOURNAL ARTICLE, info:eu-repo/semantics/published

Erythropoiesis is affected during deep saturation dives. The mechanism should be related to a downregulation of serum Erythropoietin (s-EPO) concentration or to a toxic effect of the hyperbaric hyperoxia. We evaluated s-EPO and other haematological parameters in 6 scuba divers before, during and after a 14-days guinness saturation dive (8-10 m). Athletes were breathing air at 1.8-2 ATA, under the control of a team of physicians. Serum parameters were measured before diving (T0) and: 7 days (T1), 14 days (T2) after the beginning of the dive and 2 h (T3) and 24 h (T4) after resurfacing. Hgb, and many other haematological parameters did not change whereas Ht, s-EPO, the ratio between s-EPO predicted and that observed and reticulocytes (absolute, percent) declined progressively from T0 to T3. At T4 a significant rise in s-EPO was observed. Hgb did not vary but erythropoiesis seemed to be affected as s-EPO and reticulocyte counts showed. All these changes were statistically significant. The experiment, conducted in realistic conditions of dive length, oxygen concentration and pressure, allows us to formulate some hypotheses about the role of prolonged hyperbarism on erythropoiesis. The s-EPO rise, 24 h after resurfacing, is clearly documented and related to the "Normobaric Oxygen Paradox". This evidence suggests interesting hypotheses for new clinical applications such as modulation of s-EPO production and Hgb content triggered by appropriate O2 administration in pre-surgical patients or in some anemic disease.

Cloose Loop Stimulation (CLS) algorithm is a form of rate adaptive pacing, able to provide an effective pacing rate profile not only during physical exercise but although during mental stress. To test this hypothesis CLS or accelerometers sensor (AS) rate response was compared intraindividually during a mental stress test. Methods: 36 patients (mean age 76 ± 9)implanted with a VVI-CLS Cylos Biotronik underwentmental stress test in different pacing configuration: non-rate adaptive mode (VVI), accelerometer sensor (AS) mode (VVIR), and CLS respectively. A modified Stroop test was used in order to induce mental stress. Heart rate (HR), systolic and diastolic blood pressure and pacing percentage burden were collected for 5 minutes before, during and 5minutes after the test. Results: Our study show that the average peak HR during mental stress test was significantly higher in CLS configuration than in AS and non adaptive mode. Further the average HR increase (calculated as the difference in minimum HR and the HR peak) during mental stress test was wider in CLS configuration than in VVIR and VVI. Finally, the percentage of pacing beats during mental stress test was higher in CLS configuration than with the other algorithms. Conclusion: CLS showed to be more effective than AS mode in providing a rate-adaptive pacing during mental stress. Results support the issue that CLS algorithm can detect an hemodynamic demand due to an emotional upheaval and supply a proper heart rate increase.

Introduction: CLS (Closed Loop Stimulation)algorithm showed to provide a rate-adaptive stimulation in response to haemodynamic demand due to emotional upheaval in chronotropically incompetent patients. We hypothesized that the hemodynamic benefits supplied by CLS algorithm may extend to neuro-cognitive functioning through enhanced cerebral blood perfusion. Methods: In order to test this hypothesis, we conducted a small-scale three-arm randomized controlled clinical trial involving 45 implanted patients randomly assigned to three pacing configurations: CLS (n = 15), Accelerometer Sensor (AS) mode (n = 15) and non rateadaptive mode (n = 15). A pool of ten neuropsychological tests tapping main neuro-cognitive domains (memory, attention, language, visuospatial skills and executive function) was administered to each participant before randomization and one year after. Mean change scores in cognitive measures were compared among the three pacing configurations at 1-year follow-up. Results: Statistically significant differences in change scores were found on attention and executive functioning measures. On average, patients in CLS configuration showed significant improvements on such measures, while patients in AS and non rate-adaptive modes showed non-significant deterioration trends. No statistically significant difference was found in change scores for the other neuro-cognitive parameters. Conclusion: CLS algorithm showed to be effective in improving attention and executive functioning in a small sample of chronotropically incompetent patients one year after pacing configuration. Large-scale trials are needed to corroborate such preliminary and novel results.

Introduction. A case of massive facial edema and airway obstruction secondary to an acute sialadenitis is described that occurred a few hours after a neurosurgical procedure performed in the prone position. Literature on this topic is reviewed. Case presentation. A 73-year-old Caucasian woman underwent a right parieto-occipital craniotomy to remove a meningioma. The procedure was performed in the prone position and lasted for 7 hours. One hour after the end of surgery, left submandibular gland swelling was clearly visible and in a few hours, she developed massive facial edema. Imaging (computed tomography and magnetic resonance) showed inflammatory swelling of the submandibular and parotid glands and of the periglandular tissues, undilated excretory ducts, and complete obliteration of the pharynx lumen (pharyngeal mucosa adhered to the endotracheal tube). Analgesics, corticosteroids, and antibiotics were administered. Edema regressed from the 4th postoperative day and the endotracheal tube could be removed on the 7th postoperative day. The patient was discharged from the surgical intensive care unit on the 14th postoperative day and from hospital on the 28th postoperative day. Conclusion. This is the first case report in which acute postoperative sialadenitis caused complete upper airway obstruction: only the presence of a tracheal tube avoided the need for an emergency tracheostomy. Since edema evolves insidiously, we recommend caution when removing the endotracheal tube in patients who are acutely developing postoperative sialadenitis. © 2009 Cavaliere et al; licensee Cases Network Ltd.

Adrenal insufficiency has been reported with increased frequency in critical ill patients with sepsis and other inflammatory states. Its incidence varies widely depending on the criteria used to define it and the patient population studied. Increased glucocorticoid action is essential in the stress response to acute injury and even minor degrees of adrenal insufficiency can be fatal. Recently the so-called relative or functional adrenal insufficiency (CIRCI) has been described: in this syndrome cortisol levels may be low or high but nonetheless inadequate to meet the elevated metabolic demand. Since laboratory diagnosis of adrenal insufficiency is still controversial, the diagnosis of ICU associated adrenal insufficiency is essentially a clinical diagnosis. Whether exogenous corticosteroid support may be beneficial in critical illness is still a matter of debate: most international guidelines recommend that the decision to treat patients with corticosteroids should be based on clinical criteria (low blood pressure poorly responsive to vasopressor despite adequate fluid resuscitation) rather than on tests of the hypothalamic-pituitary-adrenal axis alone. As regards specifically the role of steroids in the treatment of sepsis and septic shock, at present there are no strong evidence-based recommendations. More studies are needed to reach consensus about several issues: which is the best target population, whether a cosyntropin test should be used to guide treatment, whether fludrocortisones should be given along with hydrocortisone, and how long treatment should continue. © 2009 Bentham Science Publishers Ltd.

We demonstrate a novel optical circuit that has the potential of simultaneous demodulation and all-optical clock-recovery of 40-Gb/s wavelength-division-multiplexing nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) signals. A key device of the circuit is an ad hoc periodic fiber Bragg grating filter that simultaneously demodulates the input signals and seeds a series of clock recovery circuits. We report the complete characterization of the proposed scheme in the whole-band using a tunable transmitter. The DPSK demodulated signals show enhanced resilience to chromatic dispersion with respect to the usual NRZ ON-OFF keying format. On the other hand, the recovered clock signals are very stable and have around 200-fs root-mean-square time jitter

We demonstrate a novel optical circuit that has the potential of simultaneous demodulation and all-optical clock-recovery of 40-Gb/s wavelength-division-multiplexing nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) signals. A key device of the circuit is an ad hoc periodic fiber Bragg grating filter that simultaneously demodulates the input signals and seeds a series of clock recovery circuits. We report the complete characterization of the proposed scheme in the whole-band using a tunable transmitter. The DPSK demodulated signals show enhanced resilience to chromatic dispersion with respect to the usual NRZ ON-OFF keying format. On the other hand, the recovered clock signals are very stable and have around 200-fs root-mean-square time jitter

We study the limiting-amplification capability of a saturated Semiconductor Optical Amplifier (SOA) followed by an optical band-pass filter. We experimentally demonstrate that this simple optical circuit can be effectively exploited to realize a low-power optical limiter for amplitudemodulated pulse trains at multi-GHz repetition rate. We report very large amplitude-modulation-reduction factors for the case of 20 and 40 GHz pulse trains that are super-imposed with modulating frequencies ranging from 100kHz to several GHz.

We study the limiting-amplification capability of a saturated Semiconductor Optical Amplifier (SOA) followed by an optical band-pass filter. We experimentally demonstrate that this simple optical circuit can be effectively exploited to realize a low-power optical limiter for amplitudemodulated pulse trains at multi-GHz repetition rate. We report very large amplitude-modulation-reduction factors for the case of 20 and 40 GHz pulse trains that are super-imposed with modulating frequencies ranging from 100kHz to several GHz.

Here we report a case of leptospirosis without fever during the late stage of pregnancy in which the initial clinical presentation was more suggestive of a pregnancy-related liver dysfunction rather than an infectious disease. A 32-year-old primipara at 37 week of gestation was hospitalised with a 10-day history of nausea, vomiting, and abdominal pain without fever. Initial routine blood tests showed hyperbilirubinemia, a moderate increase in transaminase levels, severe coagulopathy and an increased creatinine level. On clinical suspicion of pregnancy-related liver dysfunction such as HELLP syndrome (hemolysis, elevated liver enzyme levels, low platelet count) or acute fatty liver of pregnancy (AFLP), emergency caesarean section was performed and a healthy baby was delivered. Postoperatively, the patient was stable, but 5 days later she developed clouding of consciousness, severe jaundice and respiratory failure. At this time, an infectious disease was considered and leptospirosis was confirmed by serological tests. In conjunction with intensive care management, antibiotic therapy was given; the patient was discharged in good condition and her baby did not develop signs of active leptospirosis. While leptospirosis is rare in pregnancy, this is the first report of acute infection without fever mimicking the clinical pattern of HELLP syndrome or AFLP.

Hyperglycemia is a common feature in critically ill patients, whether they are diabetic or not, and it is associated with unfavorable outcome. The more severe the underlying disease, the more important the hyperglycemia appears to be although, we still cannot define whether hyperglycemia is just a marker of the severity of the acute illness or rather an active contributor to poor outcome. The review of the literature on this subject published from 2001 up today conveys a massive amount of information the interpretation of which is equivocal, due to the heterogeneity of patients (nondiabetic vs. diabetic, medical intensive care unit (ICU) pts vs. surgical ICU pts) and of interventions (dose and modality of insulin infusion). The association between high glucose level and mortality is strong in critically ill patients without a previous history of diabetes. Admission hyperglycemia seems to be an independent risk factor of in-hospital mortality in patients both with and without diabetes in cardiac, cardiothoracic and neurosurgical ICUs. No data are still available on general surgical ICU patients. Tight control of blood glucose levels has been demonstrated to improve outcome in both diabetic and nondiabetic critically ill patients. In surgical ICUs, tight glucose control improves mortality and reduces morbidity only among patients admitted in ICU for more than 5 days, while outcome is not improved in patients who stay in ICU for less than 3 days. However, it is not yet understood if such favorable effect is secondary to glucose control itself or if insulin plays a part, by means of its nonglucose, anabolic effects. More randomized controlled trials are needed, addressing specific issues-such as the optimal target glucose concentration and the most effective insulin regimen-especially in the general surgical patient. © 2007 Elsevier Ltd. All rights reserved.

Ketamine is a non-competitive antagonist to the phencyclidine site of N-methyl-d-aspartate (NMDA) receptor for glutamate, though its effects are mediated by interaction with many others receptors. It has been introduced in clinical use since 1960's but today it is not largely employed as a general anaesthetic for its undesired psychic effects (emergence reactions) occurring in approximately 12% of patients. In the last decade, there has been a renewed interest in the use of subanaesthetic doses of ketamine for the treatment of acute and chronic pain. In the late 1990's, multiple prospective, randomised, controlled study has shown the efficacy of low dose of ketamine for postoperative pain relief, for analgesia during regional or local anaesthesia, and for opioid-sparing effect. At present, non-definitive conclusion can be drawn. More data are needed to define the possible long term effects and the clinical goal of ketamine use. © 2005 Bentham Science Publishers Ltd.

Determinants of improvement in oxygenation consequent to reverse Trendelenburg position in anesthetized morbidly obese patients.

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Background: Anesthetized morbidly obese patients often exhibit impaired pulmonary gas exchanges, mostly because of a reduction in functional residual capacity. At present, several approaches are suggested to ventilate these patients. Methods: The efficiency of positive end-expiratory pressure (PEEP) and reverse Trendelenburg position (RTP) were compared in order to improve oxygenation in 20 morbidly obese patients undergoing bariatric surgery. Results: Both PEEP and RTP determined a significant decrease in alveolar-arterial oxygen difference and an increase in total respiratory compliance (Ctot). RTP resulted in lower airway pressures than PEEP with similar improvements in Ctot and oxygenation. Concerning hemodynamic parameters, cardiac output (CO) significantly decreased with both PEEP and RTP. Conclusions: RTP and PEEP can be considered adequate ventilatory settings for morbidly obese patients, without any significant difference with regard to gas exchange improvement. However, the decrease in CO may partially counteract the beneficial effects on oxygenation of these ventilatory settings.

Airway suctioning is classically performed with the disconnection of the patient from the ventilator and the introduction of the suction catheter into the endotracheal tube. Alternatively, it can be accomplished with a closed suctioning system included in the ventilatory circuit, allowing to introduce the suction catheter into the airways without disconnecting the patient from the ventilator. The closed-suction system has some advantages compared to the conventional, open-suction technique. It can be helpful in limiting environmental, personnel and patient contamination and in preventing the loss of lung volume and the alveolar derecruitment associated with standard suctioning in the severely hypoxemic patients. However, the impact of the closed system on ventilator-associated pneumonia as well as its cost-effectiveness and the influence of such devices with ventilatory support remain to be assessed.

Background: Obesity causes anesthesiologists a broad variety of perioperative theoretical and practical problems. The aim of this study was to compare two protocols of anesthesia employing Isoflurane and Sevoflurane and evaluate the cardiorespiratory parameters, postoperative recovery and analgesia. Methods: 90 patients underwent biliopancreatic diversion. 60 patients (group A) received Isoflurane and 30 patients (group B) were anesthetized with Sevoflurane. Intraoperative monitoring consisted of EKG, invasive arterial pressure, SpO2, EtCO2, Etanest, Spirometry, urinary output and TOF. Cardiorespiratory parameters and end tidal expiratory concentrations of volatile agents were collected during specific phases of surgery: 1) before induction of anesthesia, 2) after intubation, 3) after skin incision, 4) after positioning of costal retractors, 5) in the reverse Trendelenburg position, 6) end of surgery. During the postoperative period the Aldrete test was carried out to evaluate the recovery from anesthesia. VAS was administered for 6 hours after the end of surgery to set the quality of analgesia. Results: No statistically significant differences in cardiorespiratory parameters were found between the two groups. Extubation time was significantly less in the Sevoflurane Group than in the Isoflurane (15 ± 7 min vs 24 ± 5 min, p< 0.05). The Sevoflurane Group showed an Aldrete score significantly higher than the Isoflurane (8.8 ± 0.3 vs 8.1 ± 0.4, p < 0.05). VAS values did not show statistical differences. Conclusion: The introduction of Sevoflurane, a volatile agent with rapid pharmacokinetic properties, seems to offer an interesting application in these patients.

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