Small Break Research Articles

Unified flavor symmetry from warped dimensions

In a model of warped extra-dimensions with all matter fields in the bulk, we propose a scenario which explains all the masses and mixings of the SM fermions. In this scenario, the same flavor symmetric structure is imposed on all the fermions of the Standard Model (SM), including neutrinos. Due to the exponential sensitivity on bulk fermion masses, a small breaking of this symmetry can be greatly enhanced and produce seemingly un-symmetric hierarchical masses and small mixing angles among the charged fermion zero-modes (SM quarks and charged leptons), thus washing out visible effects of the symmetry. If the Dirac neutrinos are sufficiently localized towards the UV boundary, and the Higgs field leaking into the bulk, the neutrino mass hierarchy and flavor structure will still be largely dominated and reflect the fundamental flavor structure, whereas localization of the quark sector would reflect the effects of the flavor symmetry breaking sector. We explore these features in an example based on which a family permutation symmetry is imposed in both quark and lepton sectors.

The interactions of molten core with different types of concretes in EPR severe accident

Sacrificial concrete is very important in the advanced European pressurized water reactor (EPR). To compare the behaviors of different kinds of sacrificial concretes in the EPR reactor pit, several sacrificial concretes were adopted in the calculation of molten core–concrete interaction molten core-concrete interaction (MCCI), i.e. the “FeSi” concrete, the siliceous concrete, and the limestone concrete. Using a computer code MELCOR, the main parameters, i.e. concrete ablation depth and rate, hydrogen generation mass and rate and temperature in a typical small break loss of coolant severe accident in EPR were calculated. The results indicate that the ablation rate decreased in the order of the “FeSi” concrete, siliceous concrete and limestone concrete. Meanwhile, the generated hydrogen mass of the “FeSi” concrete is 13% less than that of the siliceous concrete. In addition, as the basemat of reactor pit is melt through, the temperature of melt pool is the lowest for the limestone concrete and the temperature of siliceous concrete is slightly higher than that of “FeSi” concrete.

Detailed study of the Ke4 decay mode properties

The NA48/2 collaboration at CERN has accumulated an unprecedented statistics of the semileptonic Ke4 charged kaon decay in the “charged pions” (Ke4(+-)) mode K±→π+π−eν and in the “neutral pions” (Ke4(00)) mode K±→π0π0eν with respectively <1% and ∼1% background contamination, allowing a detailed study of the decay properties.More than one million Ke4(+-) decays have been analyzed leading to the improved determination of the branching ratio and detailed studies of the form factors. The resulting BR(K±e4(+−))=(4.257±0.004stat±0.016syst±0.031ext)×10−5 is 3 times more precise than the corresponding PDG value and the error is dominated by the external uncertainty from the branching ratio of the normalization decay mode. It has been possible to obtain the absolute value of the form factor fs=5.705±0.017exp±±0.017syst±0.031ext and we can now translate into absolute form all the relative form factors previously published by NA48/2. This result complements the study of the S and P wave hadronic form factors obtained by NA48/2 in a simultaneous analysis of the ππ scattering length obtained from the same data sample.Concurrently, 65,210 K± decays into π0π0e±ν have been collected, increasing the world available statistics by several orders of magnitude. A study of the differential rate provides the first measurement of the form factors. The achieved precision makes possible also the observation of small effects such as the evidence for a cusp-like structure in the distribution of the π0π0 invariant mass squared around the threshold 4mπ+2. Using a model independent description of the form factors we have obtained the final result, inclusive of radiative decays, BR(K±e4(00))=(2.552±0.010stat±0.010syst±0.032ext)×10−5, also dominated by the external uncertainty from the branching ratio of the normalization decay mode, and improving the world average precision by an order of magnitude.The detailed study of form factors is sensitive to small isospin symmetry breaking effects and brings new inputs to low energy QCD description and crucial tests of predictions from Chiral Perturbation Theory and lattice QCD calculations.

Using the Existing Fixture in a Bone Osseointegrated Implant for Switching to a Transcutaneous system: Case Reports with Three Possible Scenarios

Objective: To evaluate revision BAHA surgery in three cases switching to a transcutaneous system using the existing osseointegrated fixture. Patients: Three adults previously implanted with a tissue preserving technique, a 4 mm fixture and a Dermalock abutment (Cochlear), suffering from skin problems, were revised and implanted with a Cochlear Attract transcutaneous BAHA magnet. Intervention: The Dermalock abutment was removed permitting the skin to heal. Revision surgery introducing the Attract system implantable BIM 400 magnet was performed lifting a skin flap over the BI300 titanium fixture. No additional soft tissue flap was lifted. Follow up was scheduled at one week, at one to two months for loading and then regularly for six months. Visits with the audiologist included magnet force measurements and clinical controls by the surgeon. Main outcome measure and results: The first patient had no problems with the healing of the flap or retention force pressure by the magnet and hearing outcome was good. The second patient developed a small central skin break down over the magnet six months after the surgery requiring removal of the implanted magnet. The third patient experienced an insufficient hearing outcome and developed problems with pain when wearing the processor more than one hour. With a weaker magnet the sound processor fell off. She was switched back to a percutaneous solution again. Conclusion: Revision BAHA surgery switching the existing percutaneous system to a transcutaneous solution without an additional soft tissue flap is feasible but related to risks of complications. Careful selection of candidates is mandatory and preoperative counselling requires information of the different scenarios seen in this report.

Preliminary accident analysis of Flexblue®underwater reactor

Flexblue® is a subsea-based, transportable, small modular reactor delivering 160 MWe. Immersion provides the reactor with an infinite heat sink – the ocean – around the metallic hull. The reference design includes a loop-type PWR with two horizontal steam generators. The safety systems are designed to operate passively; safety functions are fulfilled without operator action and external electrical input. Residual heat is removed through four natural circulation loops: two primary heat exchangers immersed in safety tanks cooled by seawater and two emergency condensers immersed in seawater. In case of a primary piping break, a two-train safety injection system is actuated. Each train includes a core makeup tank, an accumulator and a safety tank at low pressure. To assess the capability of these features to remove residual heat, the reactor and its safety systems have been modelled using thermal-hydraulics code ATHLET with conservative assumptions. The results of simulated transients for three typical PWR accidents are presented: a turbine trip with station blackout, a large break loss of coolant accident and a small break loss of coolant accident. The analyses show that the safety criteria are respected and that the reactor quickly reaches a safe shutdown state without operator action and external power.

Effectiveness of a Worksite Social &amp; Physical Environment Intervention on Need for Recovery, Physical Activity and Relaxation; Results of a Randomized Controlled Trial

ObjectiveTo investigate the effectiveness of a worksite social and physical environment intervention on need for recovery (i.e., early symptoms of work-related mental and physical fatigue), physical activity and relaxation. Also, the effectiveness of the separate interventions was investigated.MethodsIn this 2×2 factorial design study, 412 office employees from a financial service provider participated. Participants were allocated to the combined social and physical intervention, to the social intervention only, to the physical intervention only or to the control group. The primary outcome measure was need for recovery. Secondary outcomes were work-related stress (i.e., exhaustion, detachment and relaxation), small breaks, physical activity (i.e., stair climbing, active commuting, sport activities, light/moderate/vigorous physical activity) and sedentary behavior. Outcomes were measured by questionnaires at baseline, 6 and 12 months follow-up. Multilevel analyses were performed to investigate the effects of the three interventions.ResultsIn all intervention groups, a non-significant reduction was found in need for recovery. In the combined intervention (n = 92), exhaustion and vigorous physical activities decreased significantly, and small breaks at work and active commuting increased significantly compared to the control group. The social intervention (n = 118) showed a significant reduction in exhaustion, sedentary behavior at work and a significant increase in small breaks at work and leisure activities. In the physical intervention (n = 96), stair climbing at work and active commuting significantly increased, and sedentary behavior at work decreased significantly compared to the control group.ConclusionNone of the interventions was effective in improving the need for recovery. It is recommended to implement the social and physical intervention among a population with higher baseline values of need for recovery. Furthermore, the intervention itself could be improved by increasing the intensity of the intervention (for example weekly GMI-sessions), providing physical activity opportunities and exercise schemes, and by more drastic environment interventions (restructuring entire department floor).Trial RegistrationNederlands Trial Register NTR2553

Simulation of the Westinghouse AP1000 Response to SBLOCA Using RELAP/SCDAPSIM

Great interest is given now to advanced nuclear reactors especially those using passive safety components. The Westinghouse AP1000 Advanced Passive pressurized water reactor (PWR) is an 1117 MWe PWR designed to achieve a high safety and performance record. The AP1000 safety system uses natural driving forces, such as pressurized gas, gravity flow, natural circulation flow, and convection. In this paper, the safety performance of the AP1000 during a small break loss of coolant accident (SBLOCA) is investigated. This was done by modelling the AP1000 and the passive safety systems employed using RELAP/SCDAPSIM code. RELAP/SCDAPSIM is designed to describe the overall reactor coolant system (RCS) thermal hydraulic response and core behaviour under normal operating conditions or under design basis or severe accident conditions. Passive safety components in the AP1000 showed a clear improvement in accident mitigation. It was found that RELAP/SCDAPSIM is capable of modelling a LOCA in an AP1000 and it enables the investigation of each safety system component response separately during the accident. The model is also capable of simulating natural circulation and other relevant phenomena. The results of the model were compared to that of the NOTRUMP code and found to be in a good agreement.

The Chicago Classification of esophageal motility disorders, v3.0.

The Chicago Classification (CC) of esophageal motility disorders, utilizing an algorithmic scheme to analyze clinical high-resolution manometry (HRM) studies, has gained acceptance worldwide. This 2014 update, CC v3.0, developed by the International HRM Working Group, incorporated the extensive clinical experience and interval publications since the prior (2011) version. Chicago Classification v3.0 utilizes a hierarchical approach, sequentially prioritizing: (i) disorders of esophagogastric junction (EGJ) outflow (achalasia subtypes I-III and EGJ outflow obstruction), (ii) major disorders of peristalsis (absent contractility, distal esophageal spasm, hypercontractile esophagus), and (iii) minor disorders of peristalsis characterized by impaired bolus transit. EGJ morphology, characterized by the degree of overlap between the lower esophageal sphincter and the crural diaphragm and baseline EGJ contractility are also part of CC v3.0. Compared to the previous CC version, the key metrics of interpretation, the integrated relaxation pressure (IRP), the distal contractile integral (DCI), and the distal latency (DL) remain unchanged, albeit with much more emphasis on DCI for defining both hypo- and hypercontractility. New in CC v3.0 are: (i) the evaluation of the EGJ at rest defined in terms of morphology and contractility, (ii) 'fragmented' contractions (large breaks in the 20-mmHg isobaric contour), (iii) ineffective esophageal motility (IEM), and (iv) several minor adjustments in nomenclature and defining criteria. Absent in CC v3.0 are contractile front velocity and small breaks in the 20-mmHg isobaric contour as defining characteristics. Chicago Classification v3.0 is an updated analysis scheme for clinical esophageal HRM recordings developed by the International HRM Working Group.

Multiple Fano Resonances Based on Different Waveguide Modes in a Symmetry Breaking Plasmonic System

Multiple Fano resonances are numerically investigated based on different waveguide modes in a nanoscale plasmonic waveguide resonator system, which consists of two grooves coupled with a metal-insulator-metal (MIM) waveguide. Simulation results show that by introducing a small structural breaking in the plasmonic resonator, both symmetric and antisymmetric waveguide modes can be excited. Due to the interaction of the symmetric and antisymmetric waveguide modes, the transmission spectra possess a sharp asymmetrical profile. Because of different origins, these Fano resonances exhibit different dependence on the parameters of the structure and can be easily tuned. These characteristics offer flexibility to design the device. This nanosensor yields a sensitivity of ~820 nm/RIU and a figure-of-merit of ~ 3.2× 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> . The utilization of the antisymmetric mode in the MIM waveguide provides a new possibility for designing high-performance plasmonic devices.

Experimental investigation of liquid entrainment in ADS-4 depressurization line with steam–water

The fourth stage Automatic Depressurization System (ADS-4) is an important part in Westinghouse AP600/AP100 which enables controlled depressurization of reactor coolant system during small break LOCA. However, the coolant may be entrained into the containment through the ADS-4 branch line simultaneously, which poses great threats to reactor core uncovering and melting. To investigate the entrainment phenomenon of ADS-4 in AP1000, ADS-4 Depressurization and Entrainment TEst Loop (ADETEL) with a scaling ratio of 1:5.6 was constructed and visualization experiments were conducted with steam–water. The experiment were conducted at atmospheric pressure with the maximum steam flow rate of 700kg/h. The entrainment processes were recorded by a high speed camera and analyzed in detail. Onset of entrainment and entrainment rate data were obtained and compared with existing test data and correlations. Empirical correlation of ADS-4 branch entrainment onset has been developed. A clear difference exists between ADETEL entrainment onset data and available correlations, which may caused by the differences in fluids physical properties, horizontal pipe flow conditions, determination of entrainment onset and d/D ratios. The entrainment onset is more likely to be reached in small d/D ratios conditions due to the stronger Bernoulli effect. Besides, AP1000 has a higher branch quality than AP600 at the same liquid level in the hot leg.

Simulation of a SBLOCA in a hot leg. Scaling considerations and application to a nuclear power plant

The main goal of this work is to study the physical phenomena observed during a Small Break Loss-Of-Coolant Accident transient performed in a small-scale Integral Test Facility and to determine the capability of the thermal hydraulic code TRACE5 to reproduce these phenomena in a scale-up model. The accident scenario analyzed is based on Test 1.2 in the frame of the OECD/NEA ROSA Project, which simulates a 1% hot leg Small Break Loss-Of-Coolant Accident in the Large Scale Test Facility of the Japan Atomic Energy Agency. During this test, natural circulation in primary loops occurs, cooling the core during some minutes. This is an important phenomenon, which needs to be checked by means of different TRACE5 models. With this aim, Test 1–2 has been simulated using a TRACE5 model reproducing the geometrical and thermal hydraulic features of Large Scale Test Facility. In order to determine if this phenomenon can be reliably extrapolated to a scale-up plant, a new TRACE5 model has been developed. The geometrical features of this scale-up model are determined using a fixed scaling ratio respect to the original LSTF features. On the other hand, 4 and 3-loop standard Westinghouse PWR models are used in order to simulate the same transient and compare the behaviour of the main thermal hydraulic variables with those obtained in the Large Scale Test Facility model and in the Large Scale Test Facility scale-up model. Results show that both Large Scale Test Facility and the scale-up models present the same behaviour during the whole transient. Important discrepancies are found in the results corresponding to 4 and 3-loop PWR TRACE5 models. In both models, natural circulation is not properly reproduced. Trying to improve the simulation results, the nodalizations of U-tubes and pressure vessel were tested. Results state that the nodalization of U-tubes clearly affects the natural circulation simulation. However, the vessel nodalization effect is not as important.

Effectiveness and adverse effects of reactor coolant system depressurization strategy with various severe accident management guidance entry conditions for OPR1000

Severe accident analysis for Korean OPR1000 with MELCOR 1.8.6 was performed by adapting a mitigation strategy under different entry conditions of Severe Accident Management Guidance (SAMG). The analysis was focused on the effectiveness of the mitigation strategy and its adverse effects. Four core exit temperatures (CETs) were selected as SAMG entry conditions, and Small Break Loss of Coolant Accident (SBLOCA), Station Blackout (SBO), and Total Loss of Feed Water (TLOFW) were selected as postulated scenarios that may propagate into severe accidents. In order to delay reactor pressure vessel (RPV) failure, entering the SAMG when the CET reached 923 K, 923 K, and 753 K resulted in the best results for SBLOCA, SBO, and TLOFW scenarios, respectively. This implies that using event-based diagnosis for severe accidents may be more beneficial than using symptom-based diagnosis. There is no significant difference among selected SAMG entry conditions in light of the operator's available action time before the RPV failure. Potential vulnerability of the RPV due to hydrogen generation was analyzed to investigate the foreseeable adverse effects that act against the accident mitigation strategies. For the SBLOCA cases, mitigation cases generated more hydrogen than the base case. However, the amount of hydrogen generated was similar between the base and mitigation cases for SBO and TLOFW. Hydrogen concentrations of containment were less than 5% before RPV failure for most cases.

Analytical estimate of phase mixing time of longitudinal Akhiezer-Polovin waves

Phase mixing of a longitudinal Akhiezer-Polovin wave subjected to a small amplitude longitudinal perturbation and its eventual breaking is studied analytically. It is well known that longitudinal Akhiezer-Polovin wave subjected to arbitrarily small longitudinal perturbation breaks via the process of phase mixing at an amplitude well below its limiting amplitude [Verma et al., Phys. Rev. Lett. 108, 125005 (2012)]. We analytically show that the phase mixing time (breaking time, ωpτmix) scales with β (phase velocity) and um(maximum fluid velocity) as ωpτmix∼2πβ3δ[1/um2−1/4], where δ is the amplitude of velocity perturbation and ωp is the non-relativistic plasma frequency. This analytical dependence of phase mixing time on β, um, and δ is further verified using numerical simulations based on Dawson sheet model.

Experimental investigation of liquid entrainment in vertical up tee branch with double-end gas inlets

Tee branches are widely used in nuclear power plants for varying purposes. The tee branch is adopted by the fourth stage Automatic Depressurization System (ADS-4) in Westinghouse AP600/AP1000 to depressurize the primary loop during the small break loss of coolant accident (SBLOCA). However, large amount of coolant will be entrained simultaneously through the ADS-4 branch which poses the threat of core uncovering and melting. Visualization experiments with double-end gas inlets were conducted to investigate the ADS-4 tee branch entrainment phenomena in AP1000. Entrainment process were recorded by high speed camera and analyzed in detail. The onset of liquid entrainment and entrainment rate data were obtained and compared with existing data and correlations, and discrepancies were found in the comparison due to the difference of test section geometric configuration. The gas flow rate has little effect on the branch quality at the same dimensionless gas chamber height in entrainment rate tests. The entrainment frequency was also studied. The test data reveal that the entrainment period decreases rapidly with the increase of entrainment rate in low range of the entrainment rate, and gradually stabilizes in high range of the entrainment rate.

Thermal–hydraulic analysis and code assessment for ATLAS 6-inch cold leg break (SBLOCA) test using MARS-KS

The thermal–hydraulic analysis using MARS-KS code was performed for 6-inch cold leg break test of ATLAS (Advanced Thermal–Hydraulic Test Loop for Accident Simulation), which was the second domestic standard problem. The calculation results were compared with experimental data to assess the code capability to simulate the transient thermal–hydraulic behavior for small break loss of coolant accident (SBLOCA). The sequence of events, except for the location of loop seal clearing (LSC) and safety injection tank (SIT) injection time was predicted well. The loop seals of 1A and 2B intermediate legs were cleared at 398s in the experiment, while that of 1A was only cleared in the calculation at the same time. The prediction showed good agreement with the experimental data for pressurizer pressure and break mass flow rate. The sudden decrease and increase of water level at the LSC time were predicted qualitatively. After LSC, there was significant water level dip at SIT injection time which was not seen in the experiment. In addition, sensitivity study to investigate the cause of core level dip at SIT injection time was performed and discussions were made for it. In conclusion, MARS-KS code has good capabilities to simulate cold leg break SBLOCA, however, including interfacial heat and mass transfer, especially condensation model needs to be improved to predict more accurate results.

Resolving the octant ofθ23via radiativeμ−τsymmetry breaking

We point out that the observed neutrino mixing pattern at low energies is very likely to originate from the 3 times 3 lepton flavor mixing matrix U which possesses the exact mu-tau permutation symmetry |U_{mu i}| = |U_{tau i}| (for i=1,2,3) at a superhigh energy scale Lambda_{mu tau} \sim 10^{14} GeV. The deviation of theta_{23} from 45^\circ and that of delta from 270^\circ in the standard parametrization of U are therefore a natural consequence of small mu-tau symmetry breaking via the renormalization-group equations (RGEs) running from Lambda_{mu tau} down to the electroweak scale Lambda_{EW} \sim 10^2 GeV. In fitting current experimental data we find that the RGE-corrected value of theta_{23} is uniquely correlated with the neutrino mass ordering: theta_{23} \simeq 42.4^\circ reported by Capozzi et al (or theta_{23} \simeq 48.9^\circ reported by Forero et al) at Lambda_{EW} can arise from theta_{23} = 45^\circ at Lambda_{mu tau} in the minimal supersymmetric standard model if the neutrino mass ordering is inverted (or normal). Accordingly, the preliminary best-fit results of delta at Lambda_{EW} can also evolve from delta = 270^\circ at Lambda_{mu tau} no matter whether the massive neutrinos are Dirac or Majorana particles.

An analysis on the severe accident progression with operator recovery actions

Analyses on the severe accident progressions for the station blackout (SBO) accident and small break LOCA (SBLOCA) initiated severe accident were performed for APR1400 by using MELCOR computer code. Operator recovery actions for decay heat removal and inventory make up using a depressurization system and safety injection pump were simulated in parallel with a simulation of the severe accident progression. Sensitivity studies on the operator actions were performed to investigate the changes in the timing of the reactor vessel failure and to determine the time allowed for the operator to prevent reactor vessel failure. Sensitivity analyses on the effect of major modeling parameters were performed additionally to quantify the uncertainties in timing. It is found that the operator has about 2h for the recovery actions after the indication of core damage by the signal of core exit thermocouple (CET) for the SBLOCA initiated severe accident, while the operator has to take immediate actions after the indication of core damage by CET for the SBO accident.

Investigation of main coolant pump trip problem in case of SB LOCA for Kozloduy Nuclear Power Plant, WWER-440/V230

This paper presents the results of thermal-hydraulic calculation of accident scenarios that involve the trip of main coolant pump (MCP) in case of Small break loss of coolant accident (SB LOCA) for WWER-440/V230 units at Kozloduy Nuclear Power Plant (KNPP), done in support of the development of Symptom Based Emergency Operating Procedures (SB EOPs) for this plant. The main purpose of these analyses is to show how the different time of MCP switching off results in primary inventory depletion in case of SB LOCA and it is reflect on peak cladding temperature. According to this, the SB LOCA scenario is regarded from the point of view of an inadequate core cooling. Therefore, the primary concern is Critical Safety Function (CSF) “Core cooling” and “Primary inventory”. High core residual heat, minimal safety injection flow and other initial conditions challenging the mentioned CSFs are the main particularities of the accepted scenarios.The RELAP5/MOD3.2 computer code has been used to perform the analyses in a WWER-440 Nuclear Power Plant (NPP) model. A model of WWER-440 based on Unit 4 of Kozloduy NPP has been developed for the system’s thermal-hydraulics code RELAP5/MOD3.2 at the Institute for Nuclear Research and Nuclear Energy – Bulgarian Academy of Sciences (INRNE-BAS), Sofia.

Association of Mayo Dysphagia Questionnaire 30-Day Scores to the Chicago Classification Diagnosis of Weak Peristalsis

Introduction: The Chicago classification of esophageal motility helps facilitate the interpretation of high resolution esophageal pressure topography studies. One unique feature of this classification is a hierarchical organization of motor disorders into those never encountered in normal individuals and those that lie outside of statistical norms. The latter group of disorders, including weak peristalsis, has less clear clinical significance and may even be present in normal subjects. The purpose of our study was to evaluate the association between weak peristalsis and the symptom of dysphagia via the Mayo Dysphagia Questionnaire-30 Day (MDQ-30) given the uncertain clinical significance of these peristaltic breaks. Methods: Consecutive patients presenting to our motility lab from May 2013 to March 2014 to receive high resolution esophageal manometry for any indication were asked to complete the MDQ-30, a tool used to reliably evaluate dysphagia symptoms over the last 30 days. A total of 100 patients completed both questionnaire and manometry. Each patient was assigned a dysphagia score based on their response to selected questions involving the symptom of dysphagia. Fisher’s exact test was used to evaluate statistical significance between the dysphagia score and the manometric diagnosis of weak peristalsis, with the level of statistical significance set at a P value of less than .05. Results: 38/100 patients met the Chicago classification definition of weak peristalsis with either large or small breaks. Out of these patients, 55% (21/38) had weak peristalsis with small breaks, 37% (14/38) had weak peristalsis with large breaks, and 8% (3/38) had both small and large peristaltic breaks. Using a cut off dysphagia score of 25 obtained from prior studies using this questionnaire, we found no statistically significant association between the symptom of dysphagia and the finding of weak peristalsis (small, large or mixed breaks) on esophageal manometry (Fisher’s exact test, p-value= 0.27). There was a slightly higher percentage of patients with normal esophageal motility compared to weak peristalsis (43% vs 39% respectively, p=0.79) who had “dysphagia” as the indication for undergoing manometry. Conclusion: Weak peristalsis is a common diagnosis encountered during the evaluation of patients receiving esophageal manometry. Our goal was to attempt to clarify the clinical significance of this diagnosis. When comparing MDQ-30 dysphagia scores to a diagnosis of weak peristalsis on high resolution esophageal pressure topography, we find no statistically significant association between weak peristalsis (large and/or small peristaltic breaks) and the symptom of dysphagia.

Comparison of High Resolution Pressure Topography and High Resolution Impedance Manometry in Patients With Non-obstructive Dysphagia

Introduction: High resolution pressure topography (HRPT) facilitates better characterization of esophageal peristalsis than conventional waveforms (CW), including recognition of ineffective esophageal motility (IEM). Likewise, high resolution impedance manometry (HRIM) provides information regarding bolus transit. It is not known if HRIM confers a diagnostic advantage over HRPT in the assessment of peristalsis in patients with non-obstructive dysphagia (NOD). Methods: Patients with NOD were evaluated with a 36-pressure and 18-impedance solid-state esophageal probe. Failed, weak and normal peristalses were identified with HRPT, HRIM and CW, independently by two assessors. Abnormal and normal peristalses were compared between the techniques. ROC curve analysis was used to determine area under the curve (AUC), sensitivity and specificity for a diagnosis of IEM using HRIM at cut-offs of 50% (HRIM50%) and 30% (HRIM30%) with CW50% and HRPT50% as references. Results: 81/111 screened patients (F/M = 57/24; mean age 53 years) were evaluated. With HRPT, IEM was seen in 28.0±3.6 % of water swallows, of which failed peristalses were seen in 11.0±2.7 % and weak peristalses in 17.0 ± 2.4 %. Of those ineffective swallows, 8.8±1.8 % were large breaks, 10.5±1.1% were small breaks and 35.4±4.0 % had transition zone defects (TZDs) (mean length 3.1±0.3 cm). Less than a third of subjects had a mean distal contractile integral (DCI)<450 mmHg-s-cm. With HRIM, IEM was seen in 35.1±4.0 %, of which 17.2 ± 3.1 % were failed peristalses and 17.9 ± 2.7% were weak peristalses. The mean distal baseline impedance was 1.3±0.1Ω. TZDs with impaired bolus clearance were seen in 19.4±3.2%. Comparing HRIM vs. HRPT, more failed peristalses (1.8±0.3 vs. 1.2±0.3, P=0.02) were identified, but weak peristalses (1.8±0.3 vs. 1.8±0.3, P=1.0) and normal peristalses (6.1±0.4 vs. 6.0±0.4,P =0.8) were similar. Using ROC curve analysis, the % of AUCs, sensitivities and specificities for HRIM50% (63.2, 48.4 and 78.0 respectively) and HRPT50% (68.2, 48.4 and 88.0 respectively) were both better than CW50% (both P<0.05). Compared with HRPT50%, the % of AUCs, sensitivities and specificities were equally better with HRIM30% (69.8, 76.2 and 63.3 respectively, P=0.007) and HRIM50% (73.3, 66.7 and 80.0 respectively, P=0.002). Conclusion: HRIM is more likely to identify peristaltic defects than HRPT, and therefore is a better test for the assessment of NOD. To diagnose IEM, HRIM30% and HRIM50% were both equally better than HRPT50% and CW50%, and should be the preferred approach. Disclosure - Dr. Rao is supported by a grant from National Institutes of Health NIH grant RO1 DK 57100-05NIHRO-1.