White Paper AGA: An Episode-of-Care Framework for the Management of Obesity-Moving Toward High Value, High Quality Care: A Report From the American Gastroenterological Association Institute Obesity Episode of Care and Bundle Initiative Work Group

The American Gastroenterological Association acknowledges the need for gastroenterologists to participate in and provide value-based care for both cognitive and procedural conditions. Episodes of care are designed to engage specialists in the movement toward fee for value, while facilitating improved outcomes and patient experience and a reduction in unnecessary services and overall costs. The episode of care model puts the patient at the center of all activity related to their particular diagnosis, procedure, or health care event, rather than on a physician's specific services. It encourages and incents communication, collaboration, and coordination across the full continuum of care and creates accountability for the patient's entire experience and outcome. This paper outlines a collaborative approach involving multiple stakeholders for gastrointestinal practices to assess their ability to participate in and implement an episode of care for obesity and understand the essentials of coding and billing for these services.

Nutrition in Chronic Disease Management in the Elderly

Older Americans experience chronic disease at rates well above other segments of our society. Rates of health services use are also 2 to 3 times that of younger age groups. The most rapidly growing segments of America's aging population are also its most nutritionally vulnerable-women, minorities, and those 85 years of age and older. The routine incorporation of nutrition screening and intervention into chronic disease management protocols will lower healthcare services usage, decrease healthcare costs, help relieve the burden of human suffering experienced by older Americans with chronic disease, and improve quality of life for our nation's elders.

Managing postacute malnutrition (undernutrition) risk

Although a direct correlation between poor nutrition status and increased risk of readmission has yet to be established, it is reasonable to assume that patients who are identified as undernourished while hospitalized would be "at increased risk of adverse outcomes" following discharge. Also, the evidence that links nonadherence to dietary prescriptions after discharge, with increased readmissions in patients with heart failure (HF), is fairly robust. Nutrition screening prior to discharge should be mandated, just as it is at admission. However, the criteria to assess a patient's ability to adequately and appropriately nourish themselves after discharge are very different from those used to diagnose and treat malnutrition on admission or during a hospital stay. The U.S. healthcare environment germane to the readmissions rates policy that was adopted for implementation in October 2012 by the Centers for Medicare & Medicaid Services is characterized. Factors critical to the successful development and implementation of a post-acute nutrition care plan are described. Nutrition-related contributors to readmissions in HF are delineated. Transitional care models that could be adapted to enhance nutrition care plan efficacy are identified, as is the need to adopt a multidisciplinary approach to nutrition in transitional care that includes care coordination and routine follow-up. An evidence-based systematic approach to determine those patients in whom palliative vs restorative nutrition care is appropriate needs to be developed.

Consensus statement: Academy of Nutrition and Dietetics and American Society for Parenteral and Enteral Nutrition: characteristics recommended for the identification and documentation of adult malnutrition (undernutrition)

The Academy of Nutrition and Dietetics (Academy) and the American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) recommend that a standardized set of diagnostic characteristics be used to identify and document adult malnutrition in routine clinical practice. An etiologically based diagnostic nomenclature that incorporates a current understanding of the role of the inflammatory response on malnutrition's incidence, progression, and resolution is proposed. Universal use of a single set of diagnostic characteristics will facilitate malnutrition's recognition, contribute to more valid estimates of its prevalence and incidence, guide interventions, and influence expected outcomes. This standardized approach will also help to more accurately predict the human and financial burdens and costs associated with malnutrition's prevention and treatment and further ensure the provision of high-quality, cost-effective nutrition care.

Consensus statement of the Academy of Nutrition and Dietetics/American Society for Parenteral and Enteral Nutrition: characteristics recommended for the identification and documentation of adult malnutrition (undernutrition)

The Academy of Nutrition and Dietetics (Academy) and the American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) recommend that a standardized set of diagnostic characteristics be used to identify and document adult malnutrition in routine clinical practice. An etiologically based diagnostic nomenclature that incorporates a current understanding of the role of the inflammatory response on malnutrition's incidence, progression, and resolution is proposed. Universal use of a single set of diagnostic characteristics will facilitate malnutrition's recognition, contribute to more valid estimates of its prevalence and incidence, guide interventions, and influence expected outcomes. This standardized approach will also help to more accurately predict the human and financial burdens and costs associated with malnutrition's prevention and treatment, and further ensure the provision of high quality, cost effective nutritional care.

Nutrition care of older adults with chronic disease: attitudes and practices of physicians and patients

OBJECTIVES

Eighty percent of older adults have at least one chronic disease. Most conditions could be improved with nutritional intervention. This scientific study assessed physician and patient knowledge of, and behaviors about nutrition, resulting in tools to guide physicians in nutrition management of chronic diseases.

METHODS

Surveys were conducted of 300 practicing physicians and 600 older adults to identify current attitudes and practices regarding the role of nutrition in chronic disease management.

RESULTS

Ninety percent of physicians surveyed recognize the relationship between nutrition and chronic disease. Yet nutrition care occurs only sporadically in primary care settings.

CONCLUSIONS

Most physicians are aware of nutrition in managing chronic disease, but a significant percentage do not routinely include nutrition in their practice. This research led to the development of tools to assist in identifying and managing the nutritional aspects of chronic disease.

Determination and importance of clinical and patient-based measures in outcome assessment of peripheral arterial occlusive disease

Therapeutic effectiveness is the overall effect of an intervention on clinical and quality-of-life measures. Traditionally, in peripheral arterial disease, this has been evaluated in terms of clinical outcomes only. The lack of correlation between quality-of-life and clinical measures means that these cannot adequately describe overall patient benefit or adverse effects from an intervention. Therefore, patient-based measures such as changes in disease-specific questionnaire scores must be included in the evaluation of therapeutic effectiveness.

Comparative model building of interleukin-7 using interleukin-4 as a template: a structural hypothesis that displays atypical surface chemistry in helix D important for receptor activation

Using a combination of theoretical sequence structure recognition predictions and experimental disulfide bond assignments, a three-dimensional (3D) model of human interleukin-7 (hIL-7) was constructed that predicts atypical surface chemistry in helix D that is important for receptor activation. A 3D model of hIL-7 was built using the X-ray crystal structure of interleukin-4 (IL-4) as a template (Walter MR et al., 1992, J Mol Biol. 224:1075-1085; Walter MR et al., 1992, J Biol Chem 267:20371-20376). Core secondary structures were constructed from sequences of hIL-7 predicted to form helices. The model was constructed by superimposing IL-7 helices onto the IL-4 template and connecting them together in an up-up down-down topology. The model was finished by incorporating the disulfide bond assignments (Cys3, Cys142), (Cys35, Cys130), and (Cys48, Cys93), which were determined by MALDI mass spectroscopy and site-directed mutagenesis (Cosenza L, Sweeney E, Murphy JR, 1997, J Biol Chem 272:32995-33000). Quality analysis of the hIL-7 model identified poor structural features in the carboxyl terminus that, when further studied using hydrophobic moment analysis, detected an atypical structural property in helix D, which contains Cys 130 and Cys142. This analysis demonstrated that helix D had a hydrophobic surface exposed to bulk solvent that accounted for the poor quality of the model, but was suggestive of a region in IL-7 that maybe important for protein interactions. Alanine (Ala) substitution scanning mutagenesis was performed to test if the predicted atypical surface chemistry of helix D in the hIL-7 model is important for receptor activation. This analysis resulted in the construction, purification, and characterization of four hIL-7 variants, hIL-7(K121A), hIL-7(L136A), hIL-7(K140A), and hIL-7(W143A), that displayed reduced or abrogated ability to stimulate a murine IL-7 dependent pre-B cell proliferation. The mutant hIL-7(W143A), which is biologically inactive and displaces [125I]-hIL-7, is the first reported IL-7R system antagonist.

Kininogens are antithrombotic proteins In vivo

Kininogens have recently been shown to possess antiadhesive, anticoagulant, and profibrinolytic properties and can inhibit platelet activation at low thrombin concentrations. To test whether kininogens have antithrombotic properties in vivo, we devised a model of limited arterial injury confined to removal of the endothelium. Brown-Norway Katholiek strain rats with an absence of low- and high-molecular-weight kininogen due to a single point mutation, A163T, were compared in the thrombosis model to the wild-type animals, which were otherwise genetically identical. Despite an equivalent vascular injury, the mean time (+/-SEM) for a 90% decrease in flow measured by laser Doppler was 38.4+/-17 minutes in the kininogen-deficient rats compared with 194+/-29 minutes in the wild-type animals (P<0.002). The degree of vascular injury was the same. No evidence for disseminated intravascular coagulation (decrease in factor V, antithrombin, or fibrinogen) or excessive fibrinolysis (elevation of fibrinogen degradation products) was found in either group of animals. The results suggest that kininogens have antithrombotic properties at low concentrations of thrombin and that inhibitory peptides derived from kininogen may constitute a new antithrombotic strategy.

A homology identification method that combines protein sequence and structure information

A new method is presented for identifying distantly related homologous proteins that are unrecognizable by conventional sequence comparison methods. The method combines information about functionally conserved sequence patterns with information about structure context. This information is encoded in stochastic discrete state-space models (DSMs) that comprise a new family of hidden Markov models. The new models are called sequence-pattern-embedded DSMs (pDSMs). This method can identify distantly related protein family members with a high sensitivity and specificity. The method is illustrated with trypsin-like serine proteases and globins. The strategy for building pDSMs is presented. The method has been validated using carefully constructed positive and negative control sets. In addition to the ability to recognize remote homologs, pDSM sequence analysis predicts secondary structures with higher sensitivity, specificity, and Q3 accuracy than DSM analysis, which omits information about conserved sequence patterns. The identification of trypsin-like serine proteases in new genomes is discussed.

A Bayes-optimal sequence-structure theory that unifies protein sequence-structure recognition and alignment

A rigorous Bayesian analysis is presented that unifies protein sequence-structure alignment and recognition. Given a sequence, explicit formulae are derived to select (1) its globally most probable core structure from a structure library; (2) its globally most probable alignment to a given core structure; (3) its most probable joint core structure and alignment chosen globally across the entire library; and (4) its most probable individual segments, secondary structure, and super-secondary structures across the entire library. The computations involved are NP-hard in the general case (3D-3D). Fast exact recursions for the restricted sequence singleton-only (1D-3D) case are given. Conclusions include: (a) the most probable joint core structure and alignment is not necessarily the most probable alignment of the most probable core structure, but rather maximizes the product of core and alignment probabilities; (b) use of a sequence-independent linear or affine gap penalty may result in the highest-probability threading not having the lowest score; (c) selecting the most probable core structure from the library (core structure selection or fold recognition only) involves comparing probabilities summed over all possible alignments of the sequence to the core, and not comparing individual optimal (or near-optimal) sequence-structure alignments; and (d) assuming uninformative priors, core structure selection is equivalent to comparing the ratio of two global means.

Diagnostic and interventional angioscopy

As an imaging modality, angioscopy provides a simple method for the careful evaluation and treatment of the lumen of native vessels and bypass grafts. When used as a diagnostic study, angioscopy can provide more accurate information regarding the flow surface than conventional tests, such as angiography or duplex imaging. It can significantly enhance the ability of the surgeon to detect flow surface problems. With the recent advance in endovascular tools, angioscopically guided luminal intervention has become an increasingly useful approach to many vascular problems. More precise treatment of endoluminal abnormalities and a reduction in incision length and soft-tissue dissection can result in decreased patient morbidity and extended patient benefit.

"Pancake kidney": a renal anomaly complicating aortic reconstruction

Pancake kidney is a rare fusion anomaly of the kidneys characterized by the presence of a displaced, lobulated pelvic renal mass of dual parenchymatous system without intervening septum. The existence of this anomaly during aortic reconstruction presents a great technical challenge. The surgical management of a 51-year-old man with a 5.0 cm aortic aneurysm and a pancake kidney is described.

Carbon dioxide angioscopy

Endovascular intervention has become an increasingly more popular method of diagnosing and treating vascular disease. Its expanding scope includes applications ranging from visualization of the peripheral vascular system to coronary artery interventions. This trend is primarily a result of the limitations of angiography, the current imaging standard, when compared to angioscopy. Multiple disease entities, including atherosclerotic plaque, embolic debris, and thrombus, can not be differentiated between based on angiographic appearance. Angioscopy is a more sensitive method of distinguishing between the above disease states by allowing direct visualization of the luminal surface. The significance of this distinction lies in the fact that the treatment options are notably different based upon the diagnosis. Yet another advantage of angioscopy is its therapeutic value in addition to its diagnostic abilities. Directed embolectomy, guide-wire or catheter placement, or pseudointimal resection are all possible through the angioscope at the time of diagnosis.

Venous outflow of the leg: anatomy and physiologic mechanism of the plantar venous plexus

PURPOSE

Mechanisms of venous outflow from the leg and foot have not been clearly defined. The purpose of this study was to evaluate the anatomy and physiologic mechanism of the plantar venous plexus and its impact on venous drainage from the tibial veins.

METHODS

Fifty phlebograms that contained complete foot and calf films were reviewed. On lateral films, the number of veins in the plantar venous plexus and its tibial outflow tract were counted. The length and diameter of the longest vein in the plantar venous system and the length of the foot arch were measured. The ratio of the length of the plantar venous plexus to the arch length was calculated. The presence or absence of valves within the plexus was recorded. Plantar venous plexus outflow was evaluated by an duplex ultrasonographic scan of the posterior tibial, anterior tibial, and peroneal veins during intermittent external pneumatic compression of the plantar surface of the foot.

RESULTS

The plantar venous plexus was composed of one to four large veins (mean, 2.7 veins) within the plantar aspect of the foot. The diameter of these veins was 4.0 +/- 1.2 mm. The veins coursed diagonally from a lateral position in the forefoot to a medial position at the level of the ankle, spanning 75% of the foot arch. Prominent valves were recognized within the plantar veins in 22 of 50 patients. The plexus coalesced into an outflow tract of one to four veins (mean, 2.5 veins) that flowed exclusively into the posterior tibial venous system. Small accessory veins that drained the plantar surface of the forefoot flowed into either the posterior tibial or peroneal veins. This pattern of selective drainage of the plantar venous plexus was confirmed by duplex imaging. Mechanical compression of the plantar venous plexus produced a mean peak velocity in the posterior tibial veins of 123 +/- 71 cm/sec, in the anterior tibial veins of 24 +/- 14 cm/sec, and in the peroneal veins of 29 +/- 26 cm/sec.

CONCLUSIONS

The plantar venous plexus is composed of multiple large-diameter veins that span the arch of the foot. Compression of the plantar venous plexus, such as that which occurs during ambulation, is capable of significantly increasing flow through the posterior tibial venous system into the popliteal vein. Its function may be integral to venous outflow from the calf and priming of the more proximal calf muscle pump.

Assessing health status in the elderly: the nutrition screening initiative

The recent dramatic growth in the population aged 65 and over is projected to continue well into the 21st century. While improved health status of most aging Americans is also expected, such is not the case in certain vulnerable subgroups at risk for poor health. This includes older women; minority groups; those aged 85 and above; older persons with limited economic resources, those isolated from family and friends; and older persons with impaired physical, cognitive, or emotional status. These factors, plus the cost implications of caring for a rapidly aging population, provided the impetus for the development of the Nutrition Screening Initiative (NSI). Established in 1990, the goal of the NSI is to promote the incorporation of routine nutrition screening and nutritional care into America's health services delivery system. The NSI has devoted its activities toward increasing the awareness of nutritional factors as they relate to the older population.

The nutrition screening initiative: a 5-year perspective

A history of the goals, activities, and accomplishments of the Nutrition Screening Initiative (NSI) is provided. A commentary on the development and intended use of the NSI's self-assessment and screening tools is given to facilitate selection of feeding devices for older Americans who need nutrition care. Additional questionnaires and interventions designed to address the needs identified through the NSI's standardized, interdisciplinary approach to the assessment of nutritional risk are described and their use encouraged. Legislative and public policy advocacy is summarized. A systemic approach to the assessment and maintenance of optimal nutritional health in the older population will have a profound effect on health care delivery systems.

Thrombolytic therapy for acute deep venous thrombosis: how much is enough?

Twenty-eight patients treated with thrombolytic therapy for acute deep venous thrombosis were monitored prospectively with non-invasive testing every 12-24h during treatment to evaluate thrombus response and whether duration of therapy was appropriate. Some 75% (21 of 28) of patients demonstrated improvement with lytic therapy with 36% (10 of 28) demonstrating complete lysis; 95% of responders (20 of 21) initiated lysis within 24h. Some 33% (7 of 21) of all responders and 64% (7 of 11) of those having partial lysis had treatment terminated during thrombus resolution but before maximal lysis. Non-invasive testing indicated that thrombolytic therapy for acute deep venous thrombosis is frequently terminated before maximal lysis of the thrombus. Monitoring thrombus response with venous duplex imaging should be part of the treatment strategy of deep venous thrombosis if thrombolytic therapy is used. This approach should increase efficacy and potentially reduce complications of thrombolytic therapy for acute deep venous thrombosis.

Reducing morbidity of thoracoabdominal aneurysm repair by preliminary axillofemoral bypass

BACKGROUND

Thoracoabdominal aneurysm (TAA) repair continues to be associated with appreciable morbidity and mortality. To reduce the substantial cardiac afterload of thoracic aortic clamping, preserve visceral, renal, and lower-extremity perfusion, and reduce spinal cord ischemia, a right axillofemoral bypass was performed before TAA resection.

PATIENTS AND METHODS

Fifteen patients undergoing repair of their TAA had a preliminary axillofemoral bypass with an 8- to 10-mm externally supported polytetrafluoroethylene graft. Nine underwent elective repair and 6 were operated on emergently. All but 2 patients (both had type IV aneurysms) had spinal fluid drainage and all had moderate hypothermia induced (31 degrees C to 32 degrees C). All visible intercostal arteries were reimplanted.

RESULTS

Requirements for pharmacologic afterload reduction were minimal. Urine output was preserved during proximal aortic and intercostal anastomoses, and acidosis was minimal. Anticoagulation was not necessary unless the aortic bifurcation was replaced, and no patient had thrombotic complications. One (7%) patient died after repair of a ruptured aneurysm, and 1 (7%) developed paraplegia and required temporary dialysis.

CONCLUSION

Preliminary axillofemoral bypass avoids the profound hemodynamic and physiologic derangement caused by clamping of the thoracic aorta, and effectively reduces the morbidity of TAA repair.

Modeling protein cores with Markov random fields

A mathematical formalism is introduced that has general applicability to many protein structure models used in the various approaches to the "inverse protein folding problem." The inverse nature of the problem arises from the fact that one begins with a set of assumed tertiary structures and searches for those most compatible with a new sequence, rather than attempting to predict the structure directly from the new sequence. The formalism is based on the well-known theory of Markov random fields (MRFs). Our MRF formulation provides explicit representations for the relevant amino acid position environments and the physical topologies of the structural contacts. In particular, MRF models can readily be constructed for the secondary structure packing topologies found in protein domain cores, or other structural motifs, that are anticipated to be common among large sets of both homologous and nonhomologous proteins. MRF models are probabilistic and can exploit the statistical data from the limited number of proteins having known domain structures. The MRF approach leads to a new scoring function for comparing different threadings (placements) of a sequence through different structure models. The scoring function is very important, because comparing alternative structure models with each other is a key step in the inverse folding problem. Unlike previously published scoring functions, the one derived in this paper is based on a comprehensive probabilistic formulation of the threading problem.

A strategy of aggressive regional therapy for acute iliofemoral venous thrombosis with contemporary venous thrombectomy or catheter-directed thrombolysis

PURPOSE

Occlusive iliofemoral venous thrombosis is associated with morbid short- and long-term consequences. Having been disappointed with standard anticoagulant therapy and systemic fibrinolysis, we embarked on an aggressive multidisciplinary regional approach to treat these patients, with the goals of therapy being (1) to eliminate iliofemoral venous thrombus, (2) to provide unobstructed venous drainage from the affected limb, and (3) to prevent recurrent thrombosis.

METHODS

Twelve consecutive patients were treated for extensive iliofemoral venous thrombosis. Each had thrombus from their infrapopliteal veins through their iliofemoral system, and four had vena caval involvement. The conditions of 11 patients failed to improve when the patients were given anticoagulants, and prior systemic fibrinolysis failed in five patients. The treatment strategy includes catheter-directed thrombolysis with intrathrombus infusion of the plasminogen activator or operative thrombectomy or venous bypass with a permanent 4 mm arteriovenous fistula (AVF).

RESULTS

Nine of 12 patients had a good or excellent clinical outcome (mean follow-up 25 months), which correlated with restored unobstructed venous drainage from the affected limb. Seven patients had catheter-directed lytic therapy attempted. In five patients the catheters were appropriately positioned, and lysis was successful. Five of the eight patients who underwent operations had successful procedures. Two of the three patients with poor operative outcomes had residual thrombus in their iliac veins or vena cava after thrombectomy (without bypass). The third patient, in whom anticoagulation was contraindicated, had an initially successful thrombectomy and AVF; however, vena caval thrombosis developed 2 months after operation. No patient had symptomatic pulmonary emboli, and routine posttreatment ventilation/perfusion lung scanning was not performed.

CONCLUSIONS

An aggressive multidisciplinary regional approach to patients with obliterative iliofemoral venous thrombosis, designed to remove thrombus and provide unobstructed venous drainage, offers substantially better clinical outcome compared with systemic fibrinolysis and standard anticoagulation. Catheter-directed thrombolysis is successful if the catheter is appropriately positioned within the thrombus. Contemporary venous thrombectomy, which includes thrombus removal, completion phlebography, AVF, and cross-pubic bypass when necessary, is associated with high success rates. Failures can be anticipated and avoided in most patients.

Mechanisms of fatty acid-induced inhibition of glucose uptake

Increased plasma FFA reduce insulin-stimulated glucose uptake. The mechanisms responsible for this inhibition, however, remain uncertain. It was the aim of this study to determine whether the FFA effect was dose dependent and to investigate its mechanism. We have examined in healthy volunteers (13 male/1 female) the effects of three steady state plasma FFA levels (approximately 50, approximately 550, approximately 750 microM) on rates of glucose uptake, glycolysis (both with 3-3H-glucose), glycogen synthesis (determined with two independent methods), carbohydrate (CHO) oxidation (by indirect calorimetry), hepatic glucose output, and nonoxidative glycolysis (glycolysis minus CHO oxidation) during euglycemic-hyperinsulinemic clamping. Increasing FFA concentration (from approximately 50 to approximately 750 microM) decreased glucose uptake in a dose-dependent fashion (from approximately 9 to approximately 4 mg/kg per min). The decrease was caused mainly (approximately 2/3) by a reduction in glycogen synthesis and to a lesser extent (approximately 1/3) by a reduction in CHO oxidation. We have identified two independent defects in glycogen synthesis. The first consisted of an impairment of muscle glycogen synthase activity. It required high FFA concentration (approximately 750 microM), was associated with an increase in glucose-6-phosphate, and developed after 4-6 h of fat infusion. The second defect, which preceded the glycogen synthase defect, was seen at medium (approximately 550 microM) FFA concentration, was associated with a decrease in muscle glucose-6-phosphate concentration, and was probably due to a reduction in glucose transport/phosphorylation. In addition, FFA and/or glycerol increased insulin-suppressed hepatic glucose output by approximately 50%. We concluded that fatty acids caused a dose-dependent inhibition of insulin-stimulated glucose uptake (by decreasing glycogen synthesis and CHO oxidation) and that FFA and/or glycerol increased insulin-suppressed hepatic glucose output and thus caused insulin resistance at the peripheral and the hepatic level.

Risk factors for poor nutritional status

Nutrition risk can be assessed in elderly populations by evaluating such factors as food intake, income, functional status, socialization, acute and chronic illness, and use of medications. Nutrition screening must become an integral component of the health care services provided for all older Americans. Nutrition screening and early intervention are primary steps in the development of a system of health care that is affordable and accessible to all.

Protein classification by stochastic modeling and optimal filtering of amino-acid sequences

The prediction of a protein's tertiary structural class from its amino-acid sequence is formulated as a signal-processing problem. The amino-acid sequence is treated as a "time series" of symbols containing signals that determine the protein's structural class. A methodology is described for building detailed stochastic signal models for recognized structural classes of single-domain proteins. We solve the problem of determining that model, from a set of candidates, which is the most probable generator of a protein's entire amino-acid sequence. The solution employs a nonlinear, optimal filtering algorithm, which is suited for implementation on parallel computer architectures. Previous approaches have only been able to classify correctly 80% of single-domain proteins within three very broad structural types, while our approach achieves this level across twelve much more detailed classes.

Angioscopy

Angiography currently is the principle diagnostic test for evaluation of the vasculature. Though this invasive radiologic procedure demonstrates vascular anatomy and areas of narrowing and blockage, it does not define the specific cause of the occlusion. This limitation may inhibit the appropriate treatment of vascular disease. Recently, a variety of endovascular tools designed for the treatment of specific disorders have been developed, such as lytic therapy for thrombotic occlusions, lasers for fibrotic occlusions, and atherectomy catheters for calcific atherosclerotic occlusions. For effective use of these tools, the specific cause of a vascular lesion must be determined. Angioscopy can enhance the use of these innovative therapies by providing a real-time panoramic view of the lumen, which permits both the diagnosis of luminal irregularities and visual guidance of specific luminal therapy.

An alternative method of salvaging occluded suprainguinal bypass grafts with operative angioscopy and endovascular intervention

PURPOSE

A study of technical feasibility was undertaken to determine whether angioscopy and parallel endovascular instrumentation could effectively evaluate and restore inflow into occluded suprainguinal grafts.

METHODS

Several endobronchial instruments were selected for adaptation for use in clearing occluded grafts under angioscopic guidance. These instruments were used in the treatment of 12 thrombosed grafts limbs in 10 patients who were admitted 1 to 40 days after occlusion. The occluded suprainguinal graft limbs were exposed just proximal to the femoral anastomosis. Blind retrograde balloon thrombectomy and clot extraction were performed. Graft limbs underwent angioscopy, and the presence of luminal defects were recorded. Endoluminal instruments were then inserted parallel to the angioscope, and luminal defects were corrected. After inflow was reestablished, the distal portion of the graft was thrombectomized, and any necessary distal revisions were performed.

RESULTS

Blind retrograde thrombectomy was successful in restoring inflow deemed normal in (67%) eight of 12 graft limbs and present but diminished in two (17%) graft limbs. Balloon thrombectomy was ineffective in restoring graft flow in two (17%) graft limbs. Angioscopy revealed luminal defects in 10 (83%) graft limbs after blind retrograde thrombectomy. Only 2 (17%) graft limbs had no luminal defects after thrombectomy. Findings included pseudointimal flap in eight of 12 (67%), adherent residual thrombus in 4 (33%), and kinked graft limbs in 2 (17%) graft limbs. Endovascular instrumentation was successful in resecting all luminal disease under angioscopic guidance. There were no deaths, no episodes of graft injury or distal embolization, and only one groin hematoma. During a mean follow-up period of 6 months (2 to 13 months), there was one late reocclusion at 7 months.

CONCLUSION

We conclude that angioscopically guided thrombectomy and endovascular graft revision is a useful approach to the treatment of the occluded suprainguinal graft. Enhanced luminal visualization permits refined diagnostic assessment and definitive therapy. This may prolong the benefit of suprainguinal reconstructions.

Popliteal venous aneurysm: report of two cases and review of the world literature

Two new cases of popliteal venous aneurysm are reported and added to the 22 other cases of popliteal venous aneurysm available for review. Both patients were first seen with acute pulmonary embolism and were treated with thrombolytic therapy followed by anticoagulation. Each had recurrent venous thromboembolism before discovery of the popliteal venous aneurysm. One popliteal venous aneurysm was diagnosed with phlebography and the second with venous duplex imaging, confirmed with phlebography. Both were surgically corrected with tangential aneurysmectomy and lateral venorrhaphy. Twenty-four cases of popliteal venous aneurysm are now available for review. Seventy-one percent (17 of 24) presented with pulmonary embolism, 88% (21 of 24) were saccular, and 96% (23 of 24) were located in the proximal popliteal vein. All but two were diagnosed by ascending phlebography. Three patients received no treatment: in two of these the outcome was not documented and the third had occasional pain. Two patients received anticoagulation without subsequent operative repair and both died of recurrent pulmonary emboli. Operative correction resulted in a 75% patency rate with 21% complications, most of which were related to postoperative anticoagulation. No patient who was operated on had subsequent pulmonary embolism, and there were no operative deaths. We suggest that all patients who have pulmonary embolism have lower-extremity venous duplex imaging. All popliteal venous aneurysms should be surgically repaired, inasmuch as nonoperative therapy results in recurrent thromboembolism and an unacceptably high mortality rate. Tangential aneurysmectomy with lateral venorrhaphy is the recommended procedure.

Registry of laparoscopic cholecystectomy and new and evolving laparoscopic techniques

To collect information on the rapid application of laparoscopic surgery, the National Laparoscopic Surgery Registry surveyed more than 4,000 of the 16,000 currently practicing laparoscopic surgeons. Preliminary analysis of the data has revealed that most of the respondents had been trained in general surgery, but a small percentage were certified only in surgical subspecialties. Surgeons acquiring skills in laparoscopic surgery had various levels of experience ranging from less than 1 year to more than 38 years in surgical practice. Nearly 90% of the respondents attended a laparoscopic cholecystectomy course with hands-on training. In those courses, an average of 16 hours was devoted to animal laboratories for acquisition of skills. Additional training in the form of a preceptorship is being undertaken by an increasing number of surgeons. The future of minimally invasive surgery is being supported by rapid advances in technology. New video systems capable of displaying three-dimensional images and miniaturized fiberoptic scopes are now available. Computer enhanced three-dimensional ultrasound images provide the surgeon with the ability to examine the content and consistency of tissues in addition to their appearance. Advances in mechanical retraction may eliminate the need for carbon dioxide insufflation of the abdomen. Tissue repair using tissue glues or laser-mediated processes may reduce the need for endocavitary suturing. These advances in technology and techniques may reduce the morbidity and mortality of these surgical procedures and, ultimately, improve the standard of care for surgical patients.

Structural analysis based on state-space modeling

A new method has been developed to compute the probability that each amino acid in a protein sequence is in a particular secondary structural element. Each of these probabilities is computed using the entire sequence and a set of predefined structural class models. This set of structural classes is patterned after Jane Richardson's taxonomy for the domains of globular proteins. For each structural class considered, a mathematical model is constructed to represent constraints on the pattern of secondary structural elements characteristic of that class. These are stochastic models having discrete state spaces (referred to as hidden Markov models by researchers in signal processing and automatic speech recognition). Each model is a mathematical generator of amino acid sequences; the sequence under consideration is modeled as having been generated by one model in the set of candidates. The probability that each model generated the given sequence is computed using a filtering algorithm. The protein is then classified as belonging to the structural class having the most probable model. The secondary structure of the sequence is then analyzed using a "smoothing" algorithm that is optimal for that structural class model. For each residue position in the sequence, the smoother computes the probability that the residue is contained within each of the defined secondary structural elements of the model. This method has two important advantages: (1) the probability of each residue being in each of the modeled secondary structural elements is computed using the totality of the amino acid sequence, and (2) these probabilities are consistent with prior knowledge of realizable domain folds as encoded in each model. As an example of the method's utility, we present its application to flavodoxin, a prototypical alpha/beta protein having a central beta-sheet, and to thioredoxin, which belongs to a similar structural class but shares no significant sequence similarity.

Adventitial elastolysis is a primary event in aneurysm formation

PURPOSE

Adventitial elastin degradation is a hallmark of abdominal aortic aneurysm (AAA) formation in human beings, although the quantitative relationship between elastin loss and AAA formation and growth is unknown. This study was undertaken to quantitate the reduction of adventitial elastin for small AAA, to determine whether the loss of this structural component parallels aneurysm growth, and to examine the ultrastructure of the remaining elastin elements.

METHODS

Longitudinal strips of anterior aneurysm wall were taken from 12 patients having elective repair of small (diameter < 5 cm, n = 4), moderate (diameter < 5 to 7 cm, n = 4), or large (diameter > 7 cm, n = 4) AAA and from six normal control subjects at autopsy. Specimens were prepared with elastin and collagen stains for histologic examination or formic acid for scanning electron microscopic evaluation of elastin architecture. Adventitial elastin content of aneurysmal and control aortas was quantitated with video microscopy and compared by aneurysm diameter.

RESULTS

The inner portion of adventitia of normal aortic wall was composed of densely compacted alternating lamellae of elastin and collagen, which were grossly disrupted in all aneurysms. The remaining elastin fibers were disorganized and tortuous. There was an 81.6% +/- 2.1% reduction in elastin lamellae and an 85.7% +/- 4.2% reduction in fibers per lamellae compared with the number in control aortas (p < 0.001). Size of the aneurysm made no difference in adventitial elastin content.

CONCLUSION

These data strongly suggest that elastolysis is a primary event in AAA formation that occurs before over loss of adventitial structural integrity and the development of small aneurysms.

Hemodynamic deterioration in chronic venous disease

Clinical deterioration of patients with chronic venous disease (CVD) has been well described and a standardized classification has been proposed. The progressive hemodynamic deterioration producing these clinical findings is less well appreciated. This study examines and correlates venous hemodynamics with clinical severity in patients with CVD. Two hundred seventy-four extremities from 149 patients with varying degrees of CVD and 56 extremities from 28 symptom-free volunteers were evaluated clinically and hemodynamically. Each limb was assessed for functional venous volume, degree of valvular insufficiency, efficiency of the calf muscle pump, and noninvasive estimate of ambulatory venous pressure. In addition, exercise venous pressures were recorded in 56 extremities from 36 patients and 9 extremities from 6 volunteers. As CVD progresses from class 0 to class 2, venous volume expands, valvular function deteriorates, the calf muscle pump becomes inefficient, and ambulatory venous hypertension develops. However, once extremities develop brawny edema or hyperpigmentation, further deterioration of limb hemodynamics does not occur. Patients with deep venous obstruction have more severe valvular insufficiency, calf muscle pump dysfunction, and ambulatory venous hypertension than have patients without evidence of obstruction. Residual volume fraction offers a reliable noninvasive estimate of ambulatory venous pressure (r = 0.76), although its correlation was significantly better for patients without venous obstruction (r = 0.86) than for those with obstruction (r = 0.40; p < 0.05). Deterioration in venous hemodynamics parallels clinical severity through class 2. Once brawny edema and hyperpigmentation occur, ulceration develops without additional deterioration of venous hemodynamics.

Why does prophylaxis with external pneumatic compression for deep vein thrombosis fail?

External pneumatic compression (EPC) devices are increasing in popularity for deep vein thrombosis (DVT) prophylaxis. Patients who have these devices applied postoperatively are assumed to have effective prophylaxis, although a number of extensive postoperative DVT complications have been observed. This study evaluates the proper application of EPC devices in patients in intensive care units and regular nursing floor units and assesses whether dedicated in-service instruction can improve proper use. In a prospective study of 138 patients with 2 or more risk factors for postoperative DVT, it was found that patients on routine nursing units had properly functioning EPC devices during 48% (306 of 636) of the visits compared with 78% (312 of 398) of the visits in the intensive care unit (ICU) (p less than 0.0001). Follow-up of patients transferred from an ICU to a regular nursing unit showed that functional application decreased from 82% (129 of 157) to 33% (40 of 122) (p less than 0.005). The compression sleeves were not applied in 84% of the nonfunctional devices and were properly in place but the pump nonfunctional in 16%. Unfortunately, dedicated in-service instruction did not improve the proper use of EPC. Although proper application of EPC is better in the ICU compared with regular nursing units, improper use is frequent and failure of DVT prophylaxis with EPC devices may be due to improper use, rather than failure of the method itself.

An approach to nutrition screening for older Americans

The Nutrition Screening Initiative suggests an adaptable, tiered approach to screening for poor nutritional status in older Americans. The first level of screening is a checklist to be completed by elderly individuals or their caregivers. This checklist, which will be widely disseminated, describes the warning signs of poor nutritional status. It is anticipated that individuals will approach their physicians on the basis of scores on this checklist. Also included are two screening tests designed to help clinicians more easily detect poor nutritional status, or risk factors for poor nutrition, in their patients. The level I screen is to be completed by a social service or health care professional, or by other trained personnel. The level II screen focuses on additional information to be obtained following referral to a physician or other qualified health care professional.

Risk factors for poor nutritional status in older Americans

Inappropriate dietary intake and chronic disease or disability place a substantial number of older adults at high risk of malnutrition. Malnutrition often results in considerable dysfunction and disability, reduced quality of life and, in some instances, premature or increased morbidity and mortality. Nutrition screening should prevent nutrition-related problems or allow early intervention. The elements that contribute to nutritional problems in the elderly must be clearly identified and prioritized. The desired goal of nutrition screening is a more vigorous older population able to maintain optimal nutrition, resulting in improved health and quality of life.