Use of mechanically powered disposable negative pressure wound therapy: recommendations and reimbursement update

Use of ultra-portable, mechanically powered disposable negative pressure wound therapy (dNPWT) has grown as an adjunctive modality to manage wounds in outpatient care and to expedite transition of inpatients to an outpatient setting. This technology has demonstrated similar efficacy and usability for mobile outpatients when compared with electrically powered negative pressure wound therapy devices. It was designed for patients with smaller, low to moderately exudating wounds and does not require batteries or a power source. However, very few studies address best practices for using dNPWT in a variety of wound types. There is a need for comprehensive clinical recommendations to better direct clinicians and patients in using this therapy. In addition, it is critical that providers are knowledgeable about processes for obtaining reimbursement for placement of dNPWT since codes and procedures differ drastically from standard NPWT. A panel meeting of experts with a high level of experience with dNPWT in varied wound types was convened to develop clinical recommendations and summarize current US reimbursement coding guidelines for the use of dNPWT. This publication summarizes the recommendations from panel members, in addition to supporting evidence, to help guide appropriate use of dNPWT. Panel recommendations regarding optimal patient and wound selection, wound preparation, proper patient training, and use of dNPWT in various wound types are included as well as clinical techniques for dressing application, bridging under offloading devices and compression, maintaining a seal, and protecting intact skin. Processes and codes for obtaining reimbursement for dNPWT are reviewed by care setting. Clinical recommendations and reimbursement guidelines summarized in this publication are meant to provide direction to clinicians in using dNPWT that potentially could translate into improved clinical and economic value.

A Boltzmann Sampler for 1-Pairs with Double Filtration

Recently, a framework considering RNA sequences and their RNA secondary structures as pairs led to some information-theoretic perspectives on how the semantics encoded in RNA sequences can be inferred. This pairing arises naturally from the energy model of RNA secondary structures. Fixing the sequence in the pairing produces the RNA energy landscape, whose partition function was discovered by McCaskill. Dually, fixing the structure induces the energy landscape of sequences. The latter has been considered originally for designing more efficient inverse folding algorithms and subsequently enhanced by facilitating the sampling of sequences. We present here a partition function of sequence/structure pairs, with endowed Hamming distance and base pair distance filtration. This partition function is an augmentation of the previous mentioned (dual) partition function. We develop an efficient dynamic programming routine to recursively compute the partition function with this double filtration. Our framework is capable of dealing with RNA secondary structures as well as 1-structures, where a 1-structure is an RNA pseudoknot structure consisting of "building blocks" of genus 0 or 1. In particular, 0-structures, consisting of only "building blocks" of genus 0, are exactly RNA secondary structures. The time complexity for calculating the partition function of 1-pairs, that is, sequence/structure pairs where the structures are 1-structures, is O(h³b³n⁶), where h, b, n denote the Hamming distance, base pair distance, and sequence length, respectively. The time complexity for the partition function of 0-pairs is O(h²b²n³).

A low cost dural closure simulation model for tomorrow's spinal neurosurgeons

Introduction: We present a low cost model that can be used to improve a trainee's skills in spinal dural closure. Development of microsurgical skills in a simulated environment provides a safe environment in which patients are protected. We argue that this is likely to improve the quality of dural closure, especially for surgeons early in their training and may lead to a commensurate reduction in post-operative CSF leak. Method: In our model, two consultant spine surgeons assessed the ability of participants to close the spinal dura. Participants were scored both quantitatively (time taken to complete the task) and qualitatively under the category of "surgical performance"- assessed by video and inspection of the closed dural substitute. Results: The cohort under assessment included senior and newly appointed consultants, clinical fellows and thirteen specialty trainees. 10 trainees were assessed a second time and a significant majority improved on both domains: 8 (80%) were faster on their second attempt; surgical performance scores also improved in the majority of trainees (90%). Conclusion: Our results, albeit with small numbers, show that a large proportion of trainees improve with practice with a reduction in overall task time and an improvement in surgical performance. Our model is cost-effective and easy to reproduce: simulation need not be an expensive exercise. This study further validates the use of simulation in modern neurosurgical training.

Sequence-structure relations of biopolymers

Motivation

DNA data is transcribed into single-stranded RNA, which folds into specific molecular structures. In this paper we pose the question to what extent sequence- and structure-information correlate. We view this correlation as structural semantics of sequence data that allows for a different interpretation than conventional sequence alignment. Structural semantics could enable us to identify more general embedded ‘patterns’ in DNA and RNA sequences.

Results

We compute the partition function of sequences with respect to a fixed structure and connect this computation to the mutual information of a sequence–structure pair for RNA secondary structures. We present a Boltzmann sampler and obtain the a priori probability of specific sequence patterns. We present a detailed analysis for the three PDB-structures, 2JXV (hairpin), 2N3R (3-branch multi-loop) and 1EHZ (tRNA). We localize specific sequence patterns, contrast the energy spectrum of the Boltzmann sampled sequences versus those sequences that refold into the same structure and derive a criterion to identify native structures. We illustrate that there are multiple sequences in the partition function of a fixed structure, each having nearly the same mutual information, that are nevertheless poorly aligned. This indicates the possibility of the existence of relevant patterns embedded in the sequences that are not discoverable using alignments.

Availability and Implementation

The source code is freely available at http://staff.vbi.vt.edu/fenixh/Sampler.zip

Contact

duckcr@vbi.vt.edu

Supplimentary Information

Supplementary data are available at Bioinformatics online.

Anticoagulation therapy in patients with stroke and atrial fibrillation: a registry-based study of acute stroke care in Surrey, UK

INTRODUCTION

Because of their high risk of stroke, anticoagulation therapy is recommended for most patients with atrial fibrillation (AF). The present study evaluated the use of anticoagulants in the community and in a hospital setting for patients with AF and its associations with stroke.

METHODS

Patients admitted with stroke to four major hospitals in County of Surrey, England were surveyed in the 2014-2016 Sentinel Stroke National Audit Programme. Descriptive statistics was used to summarise subject characteristics and χ² test to assess differences between categorical variables.

RESULTS

A total of 3309 patients, 1656 men (mean age: 73.1 years±SD 13.2) and 1653 women (79.3 years±13.0) were admitted with stroke (83.3% with ischaemic, 15.7% haemorrhagic stroke and 1% unspecified). AF occurred more frequently (χ²=62.4; p<0.001) among patients admitted with recurrent (30.2%) rather than with first stroke (17.1%). There were 666 (20.1%) patients admitted with a history of AF, among whom 304 (45.3%) were anticoagulated, 279 (41.9%) were untreated and 85 (12.8%) deemed unsuitable for anticoagulation. Of the 453 patients with history of AF admitted with a first ischaemic stroke, 138 (37.2%) were on anticoagulation and 41 (49.6%) were not (χ² = 6.3; p<0.043) and thrombolysis was given more frequently for those without prior anticoagulation treatment (16.1%) or unsuitable for anticoagulation (23.6%) compared with those already on anticoagulation treatment (8.3%; χ²=10.0; p=0.007). Of 2643 patients without a previous history of AF, 171 (6.5%) were identified with AF during hospitalisation. Of patients with AF who presented with ischaemic stroke who were not anticoagulated or deemed unsuitable for anticoagulation prior to admission, 91.8% and 75.0%, respectively, were anticoagulated on discharge.

CONCLUSIONS

The study highlights an existing burden for patients with stroke and reflects inadequate treatment of AF which results in an increased stroke burden. There is significant scope to improve the rates of anticoagulation.

Crystal structure of 2-oxopyrrolidin-3-yl 4-(2-phenyl-diazen-1-yl)benzoate

In the title compound, C17H15N3O3, the plane of the pyrrolidone ring is inclined at an angle of 59.791 (2)° to that of the azo-benzene segment, which adopts a configuration close to planar. In the crystal, mol-ecules are oriented pairwise by (2-oxopyrrolidin-3-yl)-oxy moieties at an angle of 76.257 (3)°, linked by hydrogen bonds and π-stacking inter-actions, forming zigzag supra-molecular chains parallel to [010] further linked via additional C-H⋯π inter-actions.

Evaluation of anticoagulation status for atrial fibrillation on early ischaemic stroke outcomes: a registry-based, prospective cohort study of acute stroke care in Surrey, UK

OBJECTIVE

The relationship of anticoagulation therapies with stroke severity and outcomes have been well documented in the literature. However, none of the previous research has reported the relationship of atrial fibrillation (AF)/anticoagulation therapies with urinary tract infection (UTI), pneumonia and length of stay in hyperacute stroke units (HASUs). The present study aimed to evaluate AF and anticoagulation status in relation to early outcomes in 1387 men (median age=75 years, IQR=65-83) and 1371 women (median age=83 years, IQR=74-89) admitted with acute ischaemic stroke to HASUs in Surrey between 2014 and 2016.

METHODS

We conducted this registry-based, prospective cohort study using data from the Sentinel Stroke National Audit Programme. Association between AF anticoagulation status with severe stroke on arrival (National Institutes of Health Stroke Scale score ≥16), prolonged HASU stay (>3 weeks), UTI and pneumonia within 7 days of admission, severe disability on discharge (modified Rankin Scale score=4 and 5) and inpatient mortality was assessed by logistic regression, adjusted for age, sex, hypertension, congestive heart failure, diabetes and previous stroke.

RESULTS

Compared with patients with stroke who are free from AF, those with AF without anticoagulation had an increased adjusted risk of having more severe stroke: 5.8% versus 14.0%, OR=2.4 (95% CI 1.6 to 3.6, P<0.001), prolonged HASU stay: 21.5% versus 32.0%, OR=1.4 (1.0-2.0, P=0.027), pneumonia: 8.2% versus 19.1%, OR=2.1 (1.4-2.9, P<0.001), more severe disability: 24.2% versus 40.4%, OR=1.6 (1.2-2.1, P=0.004) and mortality: 9.3% versus 21.7%, OR=1.9 (1.4-2.8, P<0.001), and AF patients with anticoagulation also had greater risk for having UTI: 8.6% versus 12.3%, OR=1.9 (1.2-3.0, P=0.004), pneumonia: 8.2% versus 11.5%, OR=1.6 (1.1-2.4, P=0.025) and mortality: 9.7% versus 21.7%, OR=1.9 (1.4-2.8, P<0.001). The median HASU stay for stroke patients with AF without anticoagulation was 10.6 days (IQR=2.8-26.4) compared with 5.8 days (IQR=2.3-17.5) for those free from AF (P<0.001).

CONCLUSIONS

Patients with AF, particularly those without anticoagulation, are at increased risk of severe stroke, associated with prolonged HASU stay and increased risk of early infection, disability and mortality.

Functional Cardiac Recovery and Hematologic Response to Chemotherapy in Patients With Light-Chain Amyloidosis (from the Stanford University Amyloidosis Registry)

Cardiac involvement is common in patients with light-chain (AL) amyloidosis and portends a poor prognosis, although little is known about the changes in cardiac mechanics after chemotherapy. We sought to explore the relation between amyloidosis staging and baseline cardiac mechanics and to investigate short-term changes in cardiac mechanics after chemotherapy. We identified 41 consecutive patients from the Stanford Amyloid Center who had echocardiograms and free light-chain values before and after chemotherapy, along with 40 age- and gender-matched controls. Echocardiographic assessment included left ventricular global longitudinal strain, E/e' ratio, and left atrial (LA) stiffness. Hematologic response to chemotherapy was defined as ≥50% reduction in the difference between the involved and the uninvolved free light chain (dFLC). The mean age was 66.9 ± 8.4 years and 66% were men. Before chemotherapy, global longitudinal strain, E/e' ratio, and LA stiffness were impaired in patients with amyloidosis compared with controls, and the severity of impairment worsened with advanced staging. After chemotherapy, hematologic response was observed in 30 (73%) patients. There was a significant association between the change in dFLC and cardiac function (E/e' ratio: r = -0.43, p = 0.01; LA stiffness: r = -0.35, p = 0.05). There was no significant improvement in cardiac mechanics in patients without a hematologic response to chemotherapy. In conclusion, amyloidosis stage correlated with noninvasive measurements of cardiac mechanics, and improvement in dFLC correlated with cardiac improvement on short-term follow-up echocardiography.

Epithelioid Angiomyolipoma - a case report and review of the literature

Herein we present the case of a 43-year-old female in whom a left renal mass was identified incidentally on imaging performed for staging of a newly diagnosed breast carcinoma. The mass was resected and histologic examination and immunohistochemistry confirmed a diagnosis of epithelioid angiomyolipoma.

Abstract TP71: Interruption of Antiplatelet and Anticoagulant Therapy Does Not Increase Risk of Recurrent Stroke in Patients with Left Ventricular Assist Devices

Introduction: Left ventricular-assist devices (LVAD) have increased survival and quality of life of patients with heart failure. Patients with LVAD have increased risks of ischemic and hemorrhagic cerebrovascular events due to device thrombosis and combined use of antiplatelet and anticoagulant agents. The safety of transient interruption of combined antithrombotic therapy after stroke is unknown.

Hypothesis: Time to resumption of combined antiplatelet and anticoagulant therapy after stroke is not associated with the incidence of recurrent cerebrovascular event.

Methods: We defined the study cohort of patients who received an LVAD using ICD-9 codes. We obtained data for patients with new cerebrovascular events while on a Heartmate-II or Heartware LVAD, and excluded those deceased from the initial event. We divided patient-events into two cohorts based on the index event: ischemic (TIA, stroke) or hemorrhagic (all intracranial hemorrhages, ICH). We used Fisher’s exact test to assess the association between recurrent ischemic event or ICH and time off combined antithrombotic therapy. We pre-specified variables for adjustment in the logistic regression analysis: age, cardiovascular risk factors, LVAD model, indication and endpoint, NIHSS score, INR and LDH levels, and baseline and change in antithrombotic therapy.

Results: The study included 48 patient-events between 2011 and 2016: 23 (48%) were ischemic (9 (40%) TIA and 14 (60%) infarcts) and 25 (52%) hemorrhagic. The ischemic event cohort had 9 (39%) recurrences, including 6 (67%) ischemic and 3 (33%) ICH. Median time to recurrence was 118 (IQR 78-388) days. All patients continued on antiplatelet, and maximum time off anticoagulant was 2 (median 0) days. Time off combined therapy was not associated with ischemic (p=0.43) or hemorrhagic recurrence (p=1.00). The ICH cohort had three (12%) recurrences: 1 (33%) ischemic and 2 (67%) hemorrhagic. Median time to recurrence was 158 (IQR 32-586) days. Median time off combined therapy was 7 (0-15) days, and not associated with ischemic (p=0.43) or hemorrhagic recurrence (p=0.83).

Conclusion: In patients with LVAD, transient interruption of combined antithrombotic therapy after stroke is not associated with increased risk of recurrent cerebrovascular events.