Effect of mannitol on platelet function during elective craniotomy in adult patients with brain tumor.

BACKGROUND: Mannitol is used in the treatment of raised intracranial pressure (ICP). The aim of this study was to investigate whether mannitol (MAN) leads to a relevant deterioration in platelet function in routine neurosurgical procedures. METHODS: Thirty-eight patients undergoing elective craniotomy due to a brain tumor with elevated ICP were included. After induction of anaesthesia a blood sample was taken (T1). The patients then received 1 g-kg-1 MAN within 30 minutes. The second blood sample (T2) was obtained 60 minutes after T1. Blood samples were examined by means of aggregometry (Multiplate®) and PFA-100® tests. RESULTS: No patient had clinical signs of increased bleeding. We could not find any deterioration in the aggregometry using Multiplate®, neither in the adenosinediphosphate (ADP), the arachidonic acid (ASPI), or the thrombin receptor activating protein (TRAP) test. PFA-100® closing times (cT) showed a significant prolongation between T1 and T2: collagen/adenosindiphosphate (COL/ADP) test 79s [70/99] and 91s [81/109]; p=0.002); collagen/epinephrine (COL/EPI) test 109s [92/129] and 122s [94/159]; p=0.0004). A subgroup analysis showed that the patients who received isotonic balanced infusions only, had no prolongation of cT, whereas the patients who received additionally gelatine solution had a significant prolongation. COL/ADP: 78s [70/98] and 91s [82/133]; p=0.0004). COL/EPI: test 111s [92/128] and 127s [103/146]; p=0.0026). Except for individual outliers, the measured values were in the normal range. CONCLUSIONS: In this study, we found no clinically relevant deterioration of platelet function in neurosurgical patients with increased ICP after administration of MAN. Changes that occurred were all within normal ranges.

Creation of a dedicated line team for critically ill patients with COVID-19: A multidisciplinary approach to maximize resource utilization during the COVID-19 pandemic.

BACKGROUND: Pandemics create challenges for medical centers, which call for innovative adaptations to care for patients during the unusually high census, to distribute stress and work hours among providers, to reduce the likelihood of transmission to health care workers, and to maximize resource utilization. METHODS: We describe a multidisciplinary vascular access team's development to improve frontline providers' workflow by placing central venous and arterial catheters. Herein we describe the development, organization, and processes resulting in the rapid formation and deployment of this team, reporting on notable clinical issues encountered, which might serve as a basis for future quality improvement and investigation. We describe a retrospective, single-center descriptive study in a large, quaternary academic medical center in a major city. The COVID-19 vascular access team included physicians with specialized experience in placing invasive catheters and whose usual clinical schedule had been lessened through deferment of elective cases. The target population included patients with confirmed or suspected COVID-19 in the medical ICU (MICU) needing invasive catheter placement. The line team placed all invasive catheters on patients in the MICU with suspected or confirmed COVID-19. RESULTS AND CONCLUSIONS: Primary data collected were the number and type of catheters placed, time of team member exposure to potentially infected patients, and any complications over the first three weeks. Secondary outcomes pertained to workflow enhancement and quality improvement. 145 invasive catheters were placed on 67 patients. Of these 67 patients, 90% received arterial catheters, 64% central venous catheters, and 25% hemodialysis catheters. None of the central venous catheterizations or hemodialysis catheters were associated with early complications. Arterial line malfunction due to thrombosis was the most frequent complication. Division of labor through specialized expert procedural teams is feasible during a pandemic and offloads frontline providers while potentially conferring safety benefits.

Noninvasive continuous arterial pressure monitoring during anesthesia induction in patients undergoing cardiac surgery.

Objective: In this study we compared noninvasive arterial pressure measurement using ClearSight™ vascular-unloading-technique (Edwards Lifesciences Corp, Irvine, CA) with invasive arterial pressure measurement during induction of anesthesia undergoing mayor cardiac surgery. Design: Prospective, monocentric. Setting: University hospital. Participants: 54 patients undergoing mayor cardiac surgery. Interventions: During induction all patients were simultaneously monitored with invasive (reference method) and noninvasive arterial pressure measurement (test-method) over a mean time period of 27 minutes. Measurements and Main Results: We observed slightly lower systolic and mean arterial pressures noninvasive than invasive. For systolic arterial pressure the mean of the differences was -18,05 mmHg (p < 0,05, SD ±16,78 mmHg), the mean arterial pressure MAP -5,47 mmHg (p < 0,05, SD ±11,08 mmHg) and for diastolic pressure -1,09 mmHg (p < 0,05, SD±11,15 mmHg),. The mean of the differences in heartrate was 1,15 (p < 0,05, SD±6,9 mmHg). When considering all measured values of the invasively measured MAP and the ClearSight ™ -MAP at the same timestamp over the recording interval, an almost identical progress can be seen that indicates a sufficient mapping of the hemodynamic changes. The percentage error for mean arterial, systolic and diastolic pressure measured by ClearSight™ amounts to 25,95 %, 26,77 % and 34,16 %, respectively. Conclusions: We conclude that ClearSight ™ is a good option for hemodynamic monitoring during induction of anesthesia. Taking into account the limitations, non-invasive arterial blood pressure measurement offers sufficient security to safely initiate anesthesia, especially when MAP is of particular interest. The use of non-invasive arterial blood pressure measurement with ClearSight ™ during induction of anesthesia in patients scheduled for major cardiac surgery is reliable and easy to use.

[Complications and success rates of subclavian vein catheterization depending on experience]. / Komplikationen und Erfolgsraten des Vena-subclavia-Katheters in Abhängigkeit der Erfahrung.

BACKGROUND: The infraclavicular puncture of the subclavian vein is a standard procedure for anesthetists. Meanwhile the literature and recommendations are clear and the use of real-time ultrasound guidance is the standard procedure; however, anesthetists will always get into special circumstances were they have to use the landmark technique, so this competence must be preserved. Feared complications of infraclavicular subclavian vein puncture are pneumothorax and arterial puncture. Up to now there is no clear learning curve for the infraclavicular subclavian vein puncture in the landmark technique performed by anesthetists. OBJECTIVE: The aim of this study was to examine the influence of the puncture experience on the success rate and mechanical complications, such as pneumothorax and arterial puncture in patients who received an infraclavicular subclavian vein puncture with the landmark technique. Three levels of experience were defined for comparison: inexperienced 0-20 punctures, moderately experienced 21-50 and experienced over 50 punctures. MATERIAL AND METHODS: Post hoc analysis of a previously published noninferiority study to examine the influence of ventilation on the pneumothorax rate in the subclavian vein puncture using the landmark technique. This analysis included 1021 anesthetized patients who were included in the original study between August 2014 and October 2017. Demographic data as well as the number of puncture attempts, puncture success, the overall rate of mechanical complications, pneumothorax rate and arterial puncture rates were calculated. RESULTS: The overall rate of mechanical complications (pneumothorax + arterial puncture) was significantly higher in the inexperienced group (0-21) compared to the experienced group (>50, 15% vs. 8.5%, respectively, p = 0.023). This resulted in an odds ratio of 0.52 (confidence interval, CI: 0.32-0.85, p = 0.027). Likewise, the rate of puncture attempts in the group of inexperienced (0-20) with 1.85 ± 1.12 was significantly higher than in the group of experienced (>50, 1.58 ± 0.99, p = 0.004) and resulted in an odds ratio of 0.59 (CI: 0.31-0.96, p = 0.028). Although the puncture attempts of the moderately experienced (21-50) compared to the inexperienced (0-20) was not significant lower, we found an odds ratio of 0.69 (CI: 0.48-0.99, p = 0.042). The rate of successful puncture was 95.1% in the experienced group versus 89.3% in the inexperienced group (p = 0.001), which resulted in an odds ratio of 2.35 (CI: 1.28-4.31, p = 0.018). When viewed individually, no significant differences were found for pneumothorax and arterial puncture. CONCLUSION: In this post hoc analysis of the puncture of the subclavian vein using the landmark technique, we found a significant reduction of puncture attempts and overall mechanical complications. At least 50 punctures seem to be necessary to achieve the end of the learning curve; however, the landmark technique should only be used under special circumstances, when real-time ultrasound is not available. Anesthetists who want to complete their repertoire and learn the landmark technique should always perform a static ultrasound examination before starting the puncture in order to reduce complications due to anatomical variations or thrombosis.

Echocardiographic guided, transatrial closure of a patent foramen ovale.

BACKGROUND: The management of an incidental patent foramen ovale found during planned cardiac surgery remains a challenge, and current guidelines are not helpful. Although evidence is accumulating, that closure of an incidental found patent foramen ovale might be beneficial, especially in planned off-pump procedures, the diagnosis of a formerly unknown patent foramen ovale with the patient on the operation table has vast consequences by making it necessary to switch to on pump, bi-caval cannulation for patent foramen ovale closure. We therefore developed a technique for transatrial closure of a patent foramen ovale, guided by transesophageal echocardiography. RESULTS: We have performed this surgery in 9 patients. None of them had a previously diagnosed patent foramen ovale. Mean age was 74 (±5) years, Operation time was 175 min (± 34 min), Clamp time 35 min (± 16 min) and Cardiopulmonary bypass time 80 (±17 min). Mortality was 0%. Periprocedural transesophageal echocardiography revealed closure of the patent foramen ovale in all cases. CONCLUSION: We report a new surgical method for transoesophageal echocardiography controlled closure of a patent foramen ovale without the need for an atriotomy. This new technique is especially useful for the closure of patent foramen ovale in the setting of on-pump and off-pump coronary artery bypass graft surgeries alike.

Inferring COVID-19 spreading rates and potential change points for case number forecasts

As COVID-19 is rapidly spreading across the globe, short-term modeling forecasts provide time-critical information for decisions on containment and mitigation strategies. A main challenge for short-term forecasts is the assessment of key epidemiological parameters and how they change when first interventions show an effect. By combining an established epidemiological model with Bayesian inference, we analyze the time dependence of the effective growth rate of new infections. Focusing on the COVID-19 spread in Germany, we detect change points in the effective growth rate that correlate well with the times of publicly announced interventions. Thereby, we can quantify the effect of interventions, and we can incorporate the corresponding change points into forecasts of future scenarios and case numbers. Our code is freely available and can be readily adapted to any country or region. IntroductionWhen faced with the outbreak of a novel epidemic like COVID-19, rapid response measures are required by individuals as well as by society as a whole to mitigate the spread of the virus. During this initial, time-critical period, neither the central epidemiological parameters, nor the effectiveness of interventions like cancellation of public events, school closings, and social distancing are known. RationaleAs one of the key epidemiological parameters, we infer the spreading rate{lambda} from confirmed COVID-19 case numbers at the example of Germany by combining Bayesian inference based on Markov-Chain Monte-Carlo sampling with a class of SIR (Susceptible-Infected-Recovered) compartmental models from epidemiology. Our analysis characterizes the temporal change of the spreading rate and, importantly, allows us to identify potential change points and to provide short-term forecast scenarios based on various degrees of social distancing. A detailed description is provided in the accompanying paper, and the models, inference, and predictions are available on github. While we apply it to Germany, our approach can be readily adapted to other countries or regions. ResultsIn Germany, interventions to contain the outbreak were implemented in three steps over three weeks: Around March 9, large public events like soccer matches were cancelled. On March 16, schools and childcare facilities as well as many non-essential stores were closed. One week later, on March 23, a far-reaching contact ban ("Kontaktsperre"), which included the prohibition of even small public gatherings as well as the further closing of restaurants and non-essential stores, was imposed by the government authorities. From the observed case numbers of COVID-19, we can quantify the impact of these measures on the disease spread (Fig. 0). Based on our analysis, which includes data until April 21, we have evidence of three change points: the first changed the spreading rate from{lambda} 0 = 0.43 (95 % credible interval (CI: [0.35, 0.51])) to{lambda} 1 = 0.25 (CI: [0.20, 0.30]), and occurred around March 6 (CI: March 2 to March 9); the second change point resulted in{lambda} 2 = 0.15 (CI: [0.12, 0.20]), and occurred around March 15 (CI: March 13 to March 17). Both changes in{lambda} slowed the spread of the virus, but still implied exponential growth (Fig. 0, red and orange traces). To contain the disease spread, and turn from exponential growth to a decline of new cases, a further decrease in{lambda} was necessary. Our analysis shows that this transition has been reached by the third change point that resulted in{lambda} 3 = 0.09 (CI: [0.06, 0.12]) around March 23 (CI: March 20 to March 25). O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=159 SRC="FIGDIR/small/20050922v3_fig0.gif" ALT="Figure 0"> View larger version (39K): org.highwire.dtl.DTLVardef@1176ccorg.highwire.dtl.DTLVardef@8e7739org.highwire.dtl.DTLVardef@13549baorg.highwire.dtl.DTLVardef@17b5d36_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFig. 0.C_FLOATNO Bayesian analysis of the German COVID-19 data (blue diamonds) reveals three change points that match the timing of publicly announced interventions. A: The inferred effective growth rate (difference between spreading and recovery rate,{lambda} * ={lambda} - ) for an SIR model with weekly reporting modulation and reporting delay that includes scenarios with one, two or three change points (red, orange, green; fitted to case reports until March 25, April 1 and April 9, respectively). The timing of the inferred change points in growth rate is consistent with the timing of German governmental interventions (depicted as *, **, and * * *). B: Comparing inferred models with the actual new reported cases per day reveals the effectiveness of governmental interventions. After the first two interventions, the number of new cases still grew exponentially (red, orange); only after the third intervention did the number of new cases start to saturate (green) or even to decline (gray, data until April 21). This illustrates that the future development strongly depends on our distancing behavior. Note the delay between a change point and the observation of changes in the number of new cases of almost two weeks a combination of reporting delay and a minimal period of evidence accumulation. C_FIG With this third change point,{lambda} transitioned below the critical value where the spreading rate{lambda} balances the recovery rate , i.e. the effective growth rate{lambda} * ={lambda} - {approx} 0 (Fig. 0, gray traces). Importantly,{lambda} * = 0 presents the watershed between exponential growth or decay. Given the delay of approximately two weeks between an intervention and first inference of the induced changes in{lambda} *, future interventions such as lifting restrictions warrant careful consideration. Our detailed analysis shows that, in the current phase, reliable short- and long-term forecasts are very difficult as they critically hinge on how the epidemiological parameters change in response to interventions: In Fig. 0 already the three example scenarios quickly diverge from each other, and consequently span a considerable range of future case numbers. Thus, any uncertainty on the magnitude of our social distancing in the past two weeks can have a major impact on the case numbers in the next two weeks. Beyond two weeks, the case numbers depend on our future behavior, for which we have to make explicit assumptions. In the main paper we illustrate how the precise magnitude and timing of potential change points impact the forecast of case numbers (Fig. 2). O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=93 SRC="FIGDIR/small/20050922v3_fig2.gif" ALT="Figure 2"> View larger version (28K): org.highwire.dtl.DTLVardef@24b42corg.highwire.dtl.DTLVardef@1b0dcc8org.highwire.dtl.DTLVardef@6ef54aorg.highwire.dtl.DTLVardef@a9f26c_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFig. 2.C_FLOATNO The timing and effectiveness of interventions strongly impact future COVID-19 cases. A: We assume three different scenarios for interventions starting on March 16: (I, red) no social distancing, (II, orange) mild social distancing, or (III, green) strict social distancing. B: Delaying the restrictions has a major impact on case numbers: strict restrictions starting on March 16 (green), five days later (magenta) or five days earlier (gray). C: Comparison of the time span over which interventions ramp up to full effect. For all ramps that are centered around the same day, the resulting case numbers are fairly similar. However, a sudden change of the spreading rate can cause a temporary decrease of daily new cases, although{lambda} > at all times (brown). C_FIG ConclusionsWe developed a Bayesian framework to infer central epidemiological parameters and the timing and magnitude of intervention effects. Thereby, the efficiency of political and individual intervention measures for social distancing and containment can be assessed in a timely manner. We find evidence for a successive decrease of the spreading rate in Germany around March 6 and around March 15, which significantly reduced the magnitude of exponential growth, but was not sufficient to turn growth into decay. Our analysis also shows that a further decrease of the spreading rate occurred around March 23, turning exponential growth into decay. Future interventions and lifting of restrictions can be modeled as additional change points, enabling short-term forecasts for case numbers. In general, our analysis code may help to infer the efficiency of measures taken in other countries and inform policy makers about tightening, loosening and selecting appropriate rules for containment.

Mannitol and the Combination of Mannitol and Gelatin Impair Whole Blood Coagulation and the Platelet Function In Vitro.

OBJECTIVE: Mannitol 20% and succinylated gelatin 4% are routinely used in neurosurgical procedures. The aim of this in vitro study was to explore the influence of both agents on blood coagulation and platelet function. METHODS: Blood from 21 healthy volunteers was obtained and then diluted so as to form five groups: (1) 7% dilution with mannitol; (2) 10% dilution with gelatin; (3) 17% dilution with isotonic balanced electrolyte solution; (4) 17% dilution with mannitol+gelatin; and (5) undiluted blood. The extrinsic thrombelastometry (EXTEM) and fibrin thrombelastometry (FIBTEM) tests were examined by rotational thrombelastometry via ROTEM®, and thrombocyte aggregometry with the aspirin inhibiting- (ASPI), adenosine diphosphate- (ADP), and thrombin-activating protein (TRAP) tests performed by Multiplate. RESULTS: In the EXTEM test clot formation time, the alpha angle, and maximum clot firmness were significantly reduced by mannitol and the combination of mannitol with gelatin. The platelet function tested in the ADP test was also significantly reduced with this combination. CONCLUSION: In this in vitro study, clinically relevant dilutions of mannitol and gelatin showed a significant inhibition of whole blood coagulation and the platelet function, which could be detrimental in neurosurgical settings.

Venous air embolism in the sitting position in cranial neurosurgery: incidence and severity according to the used monitoring.

BACKGROUND: There is an ongoing debate about the sitting position (SP) in neurosurgical patients. The SP provides a number of advantages as well as severe complications such as commonly concerning venous air embolism (VAE). The best monitoring system for the detection of VAE is still controversial. METHODS: In this retrospective analysis we compared 208 patients. Transesophageal echocardiography (TEE) or transthoracic Doppler (TTD) were used as monitoring devices to detect VAE; 101 cases were monitored with TEE and 107 with TTD. RESULTS: The overall incidence of VAE was 23% (TTD: 10%; TEE: 37%), but the incidence of clinically relevant VAE (drop in end-tidal carbon dioxide above 3 mmHg) was higher in the TTD group (9 out of 17 VAE, 53%) compared to the TEE group (19 out of 62 VAE, 31%). None of the patients with recorded VAE had clinically significant sequelae. CONCLUSIONS: In this small sample we found more VAE events in the TEE group, but the incidence of clinically relevant VAE was rare and comparable to other data. There is no consensus in the definition of clinically relevant VAE.

Neuromodulation of Limb Proprioceptive Afferents Decreases Apnea of Prematurity and Accompanying Intermittent Hypoxia and Bradycardia.

BACKGROUND: Apnea of Prematurity (AOP) is common, affecting the majority of infants born at <34 weeks gestational age. Apnea and periodic breathing are accompanied by intermittent hypoxia (IH). Animal and human studies demonstrate that IH exposure contributes to multiple pathologies, including retinopathy of prematurity (ROP), injury to sympathetic ganglia regulating cardiovascular action, impaired pancreatic islet cell and bone development, cerebellar injury, and neurodevelopmental disabilities. Current standard of care for AOP/IH includes prone positioning, positive pressure ventilation, and methylxanthine therapy; these interventions are inadequate, and not optimal for early development. OBJECTIVE: The objective is to support breathing in premature infants by using a simple, non-invasive vibratory device placed over limb proprioceptor fibers, an intervention using the principle that limb movements trigger reflexive facilitation of breathing. METHODS: Premature infants (23-34 wks gestational age), with clinical evidence of AOP/IH episodes were enrolled 1 week after birth. Caffeine treatment was not a reason for exclusion. Small vibration devices were placed on one hand and one foot and activated in 6 hour ON/OFF sequences for a total of 24 hours. Heart rate, respiratory rate, oxygen saturation (SpO2), and breathing pauses were continuously collected. RESULTS: Fewer respiratory pauses occurred during vibration periods, relative to baseline (p<0.005). Significantly fewer SpO2 declines occurred with vibration (p<0.05), relative to control periods. Significantly fewer bradycardic events occurred during vibration periods, relative to no vibration periods (p<0.05). CONCLUSIONS: In premature neonates, limb proprioceptive stimulation, simulating limb movement, reduces breathing pauses and IH episodes, and lowers the number of bradycardic events that accompany aberrant breathing episodes. This low-cost neuromodulatory procedure has the potential to provide a non-invasive intervention to reduce apnea, bradycardia and intermittent hypoxia in premature neonates. TRIAL REGISTRATION: ClinicalTrials.gov NCT02641249.

Quantitative analysis of localized sources identified by focal impulse and rotor modulation mapping in atrial fibrillation.

BACKGROUND: New approaches to ablation of atrial fibrillation (AF) include focal impulse and rotor modulation (FIRM) mapping, and initial results reported with this technique have been favorable. We sought to independently evaluate the approach by analyzing quantitative characteristics of atrial electrograms used to identify rotors and describe acute procedural outcomes of FIRM-guided ablation. METHODS AND RESULTS: All FIRM-guided ablation procedures (n=24; 50% paroxysmal) at University of California, Los Angeles Medical Center were included for analysis. During AF, unipolar atrial electrograms collected from a 64-pole basket catheter were used to construct phase maps and identify putative AF sources. These sites were targeted for ablation, in conjunction with pulmonary vein isolation in most patients (n=19; 79%). All patients had rotors identified (mean, 2.3±0.9 per patient; 72% in left atrium). Prespecified acute procedural end point was achieved in 12 of 24 (50%) patients: AF termination (n=1), organization (n=3), or >10% slowing of AF cycle length (n=8). Basket electrodes were within 1 cm of 54% of left atrial surface area, and a mean of 31 electrodes per patient showed interpretable atrial electrograms. Offline analysis revealed no differences between rotor and distant sites in dominant frequency or Shannon entropy. Electroanatomic mapping showed no rotational activation at FIRM-identified rotor sites in 23 of 24 patients (96%). CONCLUSIONS: FIRM-identified rotor sites did not exhibit quantitative atrial electrogram characteristics expected from rotors and did not differ quantitatively from surrounding tissue. Catheter ablation at these sites, in conjunction with pulmonary vein isolation, resulted in AF termination or organization in a minority of patients (4/24; 17%). Further validation of this approach is necessary.

A versatile task for assessing decision-making abilities: the truck dispatcher framework.

In neuropsychological decision-making research, several different tasks are used to measure decision-making competences in patients and healthy study participants. Unfortunately, the existing tasks are often inflexible for modification, use different scenarios, and include several gambling cues. Therefore, comparisons between participants' performances in different tasks are difficult. We developed the Truck Dispatcher Framework (TDF), in which different decision-making tasks can be designed within one unitary, flexible, and real-world-oriented story line. To test the story line, TDF analogues of three standard decision-making tasks (Game of Dice Task, Probability-Associated Gambling task, Iowa Gambling Task) were developed. In three studies with brain-healthy participants, the behavior in standard decision-making tasks and the TDF analogues of those tasks were compared. Similar behaviors indicate that the TDF tasks measure decision making appropriately. Thus, the TDF is recommended for experimental and clinical research because it allows for examining decision-making competences in tasks with different demands that take place within one unitary story line.

The cost of preventing readmissions: why surgeons should lead the effort.

In accordance with the Affordable Care Act, Medicare has instituted financial penalties for hospitals with 30-day readmission rates that exceed a predetermined value. Currently, this value only considers "excess" readmissions for myocardial infarction, heart failure, and pneumonia with a maximum fine being one per cent of total Medicare reimbursements. In 2015, this penalty will increase to three per cent and encompass more surgical diagnoses. We retrospectively reviewed a database of adult patients undergoing cardiac surgery treated at our institution in 2012 to establish whether patients with readmissions within 30 days of the index operation could have been managed more cost-effectively without readmission. A calculation of cost efficiency was performed to compare the net hospital profit for two scenarios: admitting patients versus hypothetical preventative measures. Of the 576 patients during the study period, a total of 68 (11.8%) patients with unplanned 30-day readmissions were identified. Outpatient management was determined to have been feasible for 18 (26.5%) patients. Whereas the calculated net profit for readmission was $144,000, inclusion of Medicare's penalty resulted in a loss of $11,950. A readmission reduction program with an annual cost exceeding $11,950 would lead to financial loss. The financial implications of Medicare's readmission penalty alone necessitate the development of cost-effective strategies to reduce rehospitalization.

Histoplasmosis mimicking malignant adenopathy during diagnostic thyroid lobectomy.

IMPORTANCE: Benign granulomatous disease may mimic malignant disease in the evaluation of mediastinal or pulmonary lesions. However, histoplasmosis as a cause of cervical lymphadenopathy is relatively rare. We report the first case of Histoplasma infection mimicking malignant adenopathy discovered during diagnostic thyroid lobectomy. OBSERVATIONS: A 2.5-cm, calcified, right paratracheal lymph node intimately involving the recurrent laryngeal nerve was discovered during lobectomy for a follicular lesion of undetermined significance with a positive NRAS mutation. Although metastatic thyroid cancer was the most probable diagnosis, results of gross inspection of the bisected thyroid nodule suggested a benign process. Partial removal of the node, sparing the nerve, established the diagnosis of Histoplasma capsulatum infection. CONCLUSIONS AND RELEVANCE: Histoplasmosis is a rare cause of cervical adenopathy that should be considered in cases in which a discordance arises between the malignant gross appearance of the adenopathy and the benign gross appearance of an associated thyroid nodule.

A framework for modeling and visualizing cardiovascular deformation under normal and altered circulatory conditions.

The aim of this paper is to model and visualize cardiovascular deformations in order to better understand vascular movements inside the lung and heart caused by abnormal cardiac conditions. The modeling was performed in two steps: first step involved modeling the cardiac output taking into account of the heart rate and preload blood volume, contractility and systematic vascular resistance. The second step involved deforming a 3D cine cardiac gated Magnetic Resonance Volume to the corresponding cardiac output. Cardiac-gated MR imaging of 4 healthy volunteers were acquired. For each volunteer, a total of 24 short-axis and 18 radial planar views were acquired on a 1.5 T MR scanner during a series of 12-15 second breath-hold maneuvers. A 3D multi-resolution optical flow deformable image registration algorithm was used to quantify the volumetric cardiovascular displacements for known cardiac outputs. Results show that a real-time visualization of the vascular deformations inside both the lung as well as the heart can be seen for different cardiac outputs representing normal and abnormal cardiac conditions.

Development and use of a novel cardiovascular simulator: time for a paradigm shift?

Understanding cardiovascular physiology, pharmacology, and treatment of shock is heavily emphasized in current medical school and surgical training. Performance of individuals in treatment of critical illness remains poor despite regular didactic sessions. We have developed a PC computer-based simulator capable of integrating basic hemodynamic parameters to dynamically generate a realistic patient monitor. The methodology includes physiological feedback as found in humans. The trainees are able to learn through a series of scenarios or ad lib manipulation of parameters. Participants including medical students, nurses, and residents were given a pretest before attending either a 30-minute didactic or a 10- or 30-minute simulator session. A posttest was administered to evaluate performance after the intervention. Twenty-four participants were equally randomized with 12 receiving simulator training. Although the two groups had similar pretest scores (P>0.5), the simulator group showed a 24 per cent improvement, whereas the lecture group showed a 10 per cent improvement in the posttest score (P=0.008). Simulations in surgery and critical care are in early stages of development. Access to such simulators on a personal computer can greatly enhance understanding of the cardiovascular system. These simulators appear to be very effective and may become an integral adjunct to traditional classroom teaching methods.

Stent placement for esophageal strictures: an update.

The use of stents for esophageal strictures has evolved rapidly over the past 10 years, from rigid plastic tubes to flexible self-expanding metal (SEMS), plastic (SEPS) and biodegradable stents. For the palliative treatment of malignant dysphagia both SEMS and SEPS effectively provide a rapid relief of dysphagia. SEMS are preferred over SEPS, as randomized controlled trials have shown more technical difficulties and late migration with plastic stents. Despite specific characteristics of recently developed stents, recurrent dysphagia due to food impaction, tumoral and nontumoral tissue overgrowth, or stent migration, remain a major challenge. The efficacy of stents with an antireflux valve for patients with distal esophageal cancer varies between different stent designs. Concurrent treatment with chemotherapy and/or radiotherapy seems to be safe and effective. In the future, it can be expected that removable stents will be used as a bridge to surgery to maintain luminal patency during neoadjuvant treatment. For benign strictures, new stent designs, such as fully covered SEMS and biodegradable stents, may potentially reduce complications during stent removal.