Implications of the Revisions and Revaluation of Office/Outpatient Evaluation and Management Codes for Neuroradiology Reimbursement.

In the 2020 Final Rule, the Center for Medicare & Medicaid Services adopted a new coding structure and accepted the substantial increase in valuation for office/outpatient Evaluation and Management codes set to begin in 2021. Given budget neutrality requirements, the projected increase in reimbursement will require a reduction in the conversion factor to offset such increases. The aim is to inform neuroradiologists the impact of these proposed changes on reimbursement and the profession.

Development and psychometric properties of the Psychological Therapies Outcome Scale - Intellectual Disabilities (PTOS-ID).

BACKGROUND: There are few valid and reliable psychological therapy outcome measures available for use with people with intellectual disabilities (ID). The current study involved the development of a new scale; the Psychological Therapies Outcome Scale - Intellectual Disabilities (PTOS-ID), and the examination of its validity and internal consistency. METHOD: The PTOS-ID was administered to 175 people who have ID accessing specialist ID services. The construct validity of the scale was investigated through exploratory factor analysis, concurrent validity through comparison with the Brief Symptom Inventory and internal reliability through internal consistency analysis. RESULTS: Three factors emerged from the principal components analysis with high levels of internal consistency: (1) anger and mood (α = 0.82); (2) positive well-being (α = 0.81); and (3) anxiety (α = 0.76). Factors (1) and (2) were combined to measure psychological distress (α = 0.85), which correlated strongly with the Global Severity Index of the Brief Symptom Inventory (r = 0.85). CONCLUSIONS: This preliminary study suggests that the PTOS-ID is a psychometrically robust measure of psychological distress and psychological well-being that can be used with people with ID. Further research is required to assess its reliability and ability to detect change.

Cutting cancer waiting times: streamlining cervical lymph node biopsy.

BACKGROUND: Patients with enlarged lymph nodes present to a number of different specialties and diagnosis is often made following a biopsy. OBJECTIVE: This study aimed to establish department waiting times for cervical lymph node biopsy, and compare these to the cancer services guidelines. METHODS: A retrospective audit was carried out to record patient waiting times (defined as the number of days from referral to biopsy) between May and December 2010. A proforma for referral was introduced. In addition, appointments for biopsies were arranged by a co-ordinator. A prospective re-audit was carried out from March to September 2011. RESULTS: The first audit showed that national guidelines were not met; there was a median waiting time of 74 days (interquartile range, 47-113). Re-audit demonstrated a significant reduction in waiting times using the proforma; the median waiting time had decreased to 18 days (interquartile range, 9-22). CONCLUSION: A proforma for lymph node biopsy and a designated co-ordinator streamlined the service, significantly reducing waiting times. Together, these can aid referral for meeting guidelines and improve patient care.

Atrial thrombosis: a near fatal complication of a Portacath.

Portacaths (Bard Medical Division, Georgia, USA) are routinely used for central venous access in patients with poor peripheral veins who require regular long-term venous access. Complications associated with central venous access devices, including infection and thrombosis, are well described in the literature; however, to our knowledge there have been few case reports of right atrial thrombi and pulmonary emboli related to implanted ports. This paper discusses the case of a patient who developed an atrial thrombosis 4 months after port placement and subsequent pulmonary emboli.

Hemolysis evaluation of centrifugal pumps using microcapsule suspension.

OBJECTIVES: Bovine and human blood has been widely used for in vitro hemolysis testing to evaluate centrifugal cardiac assist pumps. However, results from such tests are complicated by variations in the susceptibility of individual red blood cells to shear. The objective of this study was to evaluate the use of microcapsule suspension as an alternative to bovine or human blood for hemolysis testing. METHODS: Microcapsule suspensions of 100 micro m maximal diameter (average 79.1 micro m) with a polyurethane membrane were used. Each microcapsule contained a leuco dye, which was used to measure "hemolysis" in the suspension after exposure to mechanical stress. Six centrifugal pumps were used to measure and compare the hemolysis values of microcapsule suspensions, bovine blood and human blood. RESULTS: Correlations were significant between the hemolysis values measured using microcapsule suspensions and those using bovine blood (R = 0.965, p = 0.002) and human blood (R = 0.940, p = 0.005). CONCLUSIONS: Microcapsule suspension can be successfully used instead of blood to compare the relative hemolytic performance of centrifugal blood pumps.

Control of chironomid midge larvae in wastewater stabilisation ponds: comparison of five compounds.

Chironomid midge larvae are a valuable component of wastewater stabilisation pond (WSP) ecology. However, in high numbers, adult midge swarms can be a nuisance to near-by urban areas. Improving WSP treatment by incorporating aerobic or maturation ponds or by the addition of pre-treatment to reduce organic loading also increases the availability of aerobic sediment (midge larva habitat) in the pond system and the potential for midge nuisance problems. The efficacy of Maldison, an organophosphate traditionally used to control midge larvae in New Zealand WSPs, was compared to Bacillus thuringiensis var. israelensis (Bti), Methoprene, Pyriproxyfen and Diflubenzuron which are all more specific to insects and have fewer adverse environmental effects. Initial laboratory trials established the concentration of each compound required to achieve 95% control of the midge population. During 21-day small-scale trials within the WSP, Bti, Diflubenzuron and Maldison reduced live larvae numbers substantially (80-89%) compared to controls and adult midge emergence was markedly reduced by all compounds (72-96%). Large-scale trials with Bti (Vectobac WG) powder (1000 microg/L) only caused a slight reduction in midge larvae numbers compared to controls and had little effect on adult emergence, however, Methoprene (Prolink XRG granules) (50 microgAI/L) reduced midge adult emergence by approximately 80% over 25 days and has been used successfully to control several midge nuisance outbreaks.

In vivo hemodynamic performance of the Cleveland Clinic CorAide blood pump in calves.

BACKGROUND: The Cleveland Clinic CorAide left ventricular assist system is based on a small implantable continuous-flow centrifugal blood pump with a completely suspended rotating assembly designed for long-term circulatory support (5 to 10 years). METHODS: Between June 1999 and August 2000, the CorAide blood pump was implanted in 10 calves for 1 month and in 3 calves for 3 months. RESULTS: The mean pump flow and arterial pressure were 6.1 +/- 1.1 L/min and 97 +/- 5 mm Hg, respectively. The mean plasma free-hemoglobin level after postoperative day 3 was 2.0 +/- 1.8 mg/dL. Renal and hepatic function remained normal in all cases. There was no incidence of mechanical failure, hemolysis, bleeding, or systemic organ dysfunction in any of the cases. Significant findings at autopsy were limited to two cases of renal infarction, one of which was associated with an outflow graft infection. CONCLUSIONS: The CorAide blood pump is easily implanted, reliable, nonhemolytic, and nonthrombogenic, positioning it as a leading third-generation, continuous-flow left ventricular assist system with a completely suspended rotor.

Numeric flow simulation for an innovative ventricular assist system secondary impeller.

The secondary impeller of the Cleveland Clinic Foundation Innovative Ventricular Assist System heart pump is designed to pump the blood from the journal bearing through the annulus back to the discharge to rejoin the main flow. It is crucial, however, that the amount of hemolysis and potential for thrombus formation is minimized. Based on our earlier computational fluid analysis of the initial design, an improved secondary impeller has been proposed. The objective of this work was to analyze the flow with the new impeller configuration by computational fluid dynamics and to find out where in the geometry hemolysis becomes high, as well as where the potential for thrombosis exists. The present work includes: 1) visualizing the 3-dimensional flow pattern in the secondary impeller cavity, 2) investigating the tip clearance effect, and 3) estimating the shear stress distribution as a measure for blood damage caused in the secondary impeller cavity.

Numeric modeling of the cardiovascular system with a left ventricular assist device.

A numeric model consisting of a lump-parameter cardiovascular system (CVS) model and a model for the Cleveland Clinic Implantable Ventricular Assist System (IVAS), a nonpulsatile rotary pump designed to augment the failing left ventricle, are described in this paper. The purposes of this study were to 1) observe the hemodynamic interactions between CVS and IVAS under various physiologic and pathophysiologic conditions running at different speeds; and 2) allow testing and optimization of various IVAS control algorithms. An existing numeric model of CVS (24 coupled differential equations, representing all cardiac chambers and systemic and pulmonary vasculature) was modified to add the IVAS pump as an auxiliary chamber between the left ventricle and aorta with pressure-flow-speed characteristics derived from in vitro testing. Simulations were conducted for ventricles with normal and abnormal systolic and diastolic dysfunction at different exercise levels with the pump running at various speeds. Computer simulations show that 1) numeric modeling is useful for predicting hemodynamic response of CVS to IVAS in various circumstances; 2) IVAS results in normalization of cardiac output, especially in failing hearts, although with reduced pulse pressure; and 3) various control algorithms allowing adaptation of IVAS to physiologic demands of CVS could be developed based on the simulation study.

Stable blood lubricated hydrodynamic journal bearing with magnetic loading.

The Cleveland Clinic Foundation's Innovative Ventricular Assist System (IVAS) is distinguished by the use of a special hydrodynamic journal bearing to support the rotating assembly of the blood pump. In a permanently implanted blood pump, this bearing's characteristics of long life and high reliability are of paramount importance. In addition, this bearing's inherent self-pumping flow and the axial through flow caused by an imposed end-to-end pressure difference provides good washing, thus guarding against deposition. The basic computer analysis and preliminary testing results of this bearing were previously presented. This article reports the ongoing studies (both analytic and in vitro tests) on this innovative bearing as a component of the IVAS in general, with particular emphasis on its stable operating characteristics and reliability. The absence of vibration attributable to hydrodynamic instabilities related to the thick fluid film are both calculated and demonstrated during testing. A stable operating center of the rotor is shown to be inherent under magnetic side loads and resulting hydrodynamic bearing forces. A low shear as a result of large fluid-film thicknesses has been calculated, and low hemolysis has been shown by in vitro testing. Several unique design features of the bearing are believed to be responsible for this high level of performance.

Cleveland Clinic continuous flow blood pump: progress in development.

The Cleveland Clinic continuous flow blood pump is the central element of our innovative ventricular assist system (IVAS). Recent progress has been made in the design/fabrication of a pulsatile mock loop, journal bearing materials testing, and evaluation of a system control algorithm. These results have allowed an acceleration of our program.

Analysis of a new PM motor design for a rotary dynamic blood Pump.

The permanent magnet (PM) motor for a rotary dynamic blood pump requires high power density to coordinate the motor size with the limited pump space and high efficiency to reduce the size and weight of the associated batteries. The motor also serves as a passive axial magnetic thrust bearing, a reacting hydraulic force, and provides a stabilizing force for the radial journal bearing. This article presents analysis of a new PM motor for the blood pump application. High power density is achieved by using the Halbach magnetic array, and high efficiency is accomplished by optimizing the rotor magnet assembly and the stator slots/windings. While both radial and axial forces are greatly enhanced, pulsating components of the torque and force are also significantly reduced.

The analysis, design, and testing of a blood lubricated hydrodynamic journal bearing.

The Cleveland Clinic Foundation's Innovative Ventricular Assist System (IVAS) uses a hydrodynamic journal bearing to support the rotating assembly of the blood pump. Bearing dimensions are chosen so that a stable film of lubricant develops and separates stationary and rotating pump surfaces during operation. This bearing type provides several advantages for a permanently implanted device, including essentially no wear for very long life and very high reliability, as well as a self pumping action that generates circumferential wash flow and thus lowers the risk of bearing associated deposition. However, these advantages are accompanied by design issues not encountered with typical journal bearing, such as low shear stress, bearing ends that are not at atmospheric pressure, and low radial bearing loads. To address these issues, several concepts for a hydrodynamic blood bearing were designed and analyzed using a special computer code to perform parametric studies. This design analysis code was developed to define optimum bearing performance under selected load and speed ranges and within practical tolerances. Results showed the range of dimensions and conditions over which an effective, reliable, blood lubricated journal bearing can be designed. Subsequent bench testing has validated the theoretical conclusions and shown this bearing type to be very robust in a blood pump application.

Selection and evaluation of blood- and tribologically compatible journal bearing materials.

A critical issue in the Cleveland Clinic Foundation (CCF) Innovative Ventricular Assist System (IVAS) blood pump is the selection of materials for the blood-lubricated journal bearing. Under normal operating conditions, the journal bearing geometry creates a thick blood film that separates the rotating and stationary surfaces. However, since start-up and certain transients could cause temporary contact, the material pair selected for these surfaces must be both tribologically and blood compatible. Combinations of two biocompatible alloys were tested: a titanium-zirconium-niobium alloy (Ti-13Zr-13Nb) and a zirconium-niobium alloy (Zr-2.5Nb). A standard pin-on-disk tester was used, with the contact surfaces lubricated by glycerol/saline mixtures simulating the viscosity range of blood. One test series evaluated start-up conditions; the other modeled a high-speed rub that might occur if the fluid film broke down. Results showed that the preoxidized Zr-2.5Nb pin/Ti-13Zr-13Nb disk combination was superior at all sliding velocities; a self-mated Zr-2.5Nb pair also showed promise. The oxide film on a self-mated Ti-13Zr-13Nb pair, and a Ti-13Zr-13Nb pin and Zr-2.5Nb disk combination did not show adequate wear life. More work remains to explain distinct performance differences of certain combinations, with more data needed on mechanical properties of thin, hard coatings on softer metal substrates.

Design of a DSP controller for an innovative ventricular assist system.

The design and development of the digital signal processor controller for an innovative ventricular assist system is presented. A DSP56005 is used as the central processor, with other peripheral components. System hardware and software were developed through the advanced development system, and stand alone operation of the system was also accomplished. Two different control modes--current control mode and speed control mode--were developed and investigated. Performance of efficiency and dynamic response were examined through experimental testing.

Development of a 6 x 18 inch rheology tunnel for experimental fluid dynamics investigation.

The Ohio State University (OSU) and the Cleveland Clinic Foundation (CCF) developed a 6 x 18 inch low velocity Rheologic Research Tunnel to do flow visualization and other experimental fluid studies, particularly on scaled-up models of cardiovascular devices, such as the CCF's Innovative Ventricular Assist System. The large test section (TS) permits detailed data to be obtained that would be inaccessible with a smaller test prototype. A particular feature of the OSU-CCF program is the use of a non-Newtonian blood analog (NNBA), so the effect of the shear-thinning behavior of blood on the local development of separation, stagnation, and flow patterns can be studied. The TS can simulate a pressure driven slit flow of 6 x 18 in., or the external flow around a vane or blade having an aspect ratio of 1. Maximum pressure is 8.5 psig, while the maximum velocity is 21.7 in/sec. The fluid supply tank has a capacity of 500 gal of NNBA and, with its associated filtration and circulation systems, can be adapted to studies of large transparent models better studied outside the TS. Using 2 pumps, flow rates of 98-610 gal/min can be provided. Instrumentation includes thermistors, a 48 port pressure scanner with pressure transducers, a data acquisition system, and a digital video camera. Dye and hydrogen bubble systems have been developed. Development of such a facility presents problems not encountered in more typical water tables or wind tunnels. These include fundamental issues such as providing a uniform flowfield; practical issues with respect to priming, operating, and obtaining data from the system; and safety considerations. For the very large volume of NNBA, a xanthan gum solution is used, whose shear-thinning behavior depends not only on concentration, but also on age and prior shear history. The lessons learned are presented, permitting others to efficiently develop systems suitable to their testing needs.

Blood flow analysis for the secondary impeller of an IVAS heart pump.

The rotodynamic heart pump (IVAS), designed by the Cleveland Clinic Foundation, includes a secondary flow path along the journal bearing, through a secondary impeller, and over the rotor outer surface. The flow behaviors of the blood through the journal bearing and the secondary impeller are investigated by a computational fluid dynamics method that solves the 3-dimensional Navier-Stokes equations using a new solution algorithm. Results of the analyses include: 1) the blood flow patterns within the journal bearing, 2) the effect of the non-uniform bearing clearance on the flow patterns of the impeller cavity, 3) the flow patterns around a secondary impeller blade that include effects of tip clearance and the gap between the blade and the inner or outer side wall, 4) effects of the blade angles on the secondary impeller performance, and 5) the shear stress distribution.

Flow analysis of the Cleveland Clinic centrifugal pump.

An implantable ventricular assist blood pump is being developed by the Cleveland Clinic Foundation in cooperation with the NASA Lewis Research Center. At the nominal design condition, the pump provides blood flow at the rate of 5 L/min at a pressure rise of 100 mmHg and a rotation speed of 3000 RPM. Bench testing of the centrifugal pump in a water/glycerin mixture has provided flow and pressure data at several rotative speeds. A one-dimensional empirically based pump flow analysis computer code developed at NASA Lewis Research Center has been used in the design process to simulate the flow in the primary radial pump stage. The computer model was used to size key impeller and volute geometric parameters that influence pressure rise and flow. Input requirements to the computer model include a simple representation of the pump geometry. The model estimates the flow conditions under design and off-design operating conditions at the impeller leading and trailing edges, and the volute inlet and exit. Output from the computer model is compared to flow and pressure data obtained from bench testing.