Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Observation of persistent species temperature separation in inertial confinement fusion mixtures

The injection and mixing of contaminant mass into the fuel in inertial confinement fusion (ICF) implosions is a primary factor preventing ignition. ICF experiments have recently achieved an alpha-heating regime, in which fusion self-heating is the dominant source of yield, by reducing the susceptibility of implosions to instabilities that inject this mass. We report the results of unique separated reactants implosion experiments studying pre-mixed contaminant as well as detailed high-resolution three-dimensional simulations that are in good agreement with experiments. At conditions relevant to mixing regions in high-yield implosions, we observe persistent chunks of contaminant that do not achieve thermal equilibrium with the fuel throughout the burn phase. The assumption of thermal equilibrium is made in nearly all computational ICF modeling and methods used to infer levels of contaminant from experiments. We estimate that these methods may underestimate the amount of contaminant by a factor of two or more.

The role of multiple ionization of H2O in heavy ion collisions

Collisional ionization processes involving H₂O molecules and C⁶⁺, O⁸⁺, Si¹³⁺ ions are studied by means of the classical trajectory Monte Carlo method using molecular orbital calculations to define the ionization stages of the water molecule. Net total and single-differential cross sections in energy and angle are obtained by using a newly developed model that goes beyond the commonly applied one-active electron approximation. This model allows us to access the fraction of electron emission arising from single and multiple electron ionization. Calculated cross sections are contrasted and benchmarked against available experimental data at impact energies in the MeV/u range. The present results highlight the important role of multiple ionization in the emission of electrons where we find the majority of electrons emitted with energies greater than ~50 eV arise from multiple ionization collisions.

First Liquid Layer Inertial Confinement Fusion Implosions at the National Ignition Facility

The first cryogenic deuterium and deuterium-tritium liquid layer implosions at the National Ignition Facility (NIF) demonstrate D_{2} and DT layer inertial confinement fusion (ICF) implosions that can access a low-to-moderate hot-spot convergence ratio (12<CR<25). Previous ICF experiments at the NIF utilized high convergence (CR>30) DT ice layer implosions. Although high CR is desirable in an idealized 1D sense, it amplifies the deleterious effects of asymmetries. To date, these asymmetries prevented the achievement of ignition at the NIF and are the major cause of simulation-experiment disagreement. In the initial liquid layer experiments, high neutron yields were achieved with CRs of 12-17, and the hot-spot formation is well understood, demonstrated by a good agreement between the experimental data and the radiation hydrodynamic simulations. These initial experiments open a new NIF experimental capability that provides an opportunity to explore the relationship between hot-spot convergence ratio and the robustness of hot-spot formation during ICF implosions.

Comparisons of NIF convergent ablation simulations with radiograph data

A technique for comparing simulation results directly with radiograph data from backlit capsule implosion experiments will be discussed. Forward Abel transforms are applied to the kappa*rho profiles of the simulation. These provide the transmission ratio (optical depth) profiles of the simulation. Gaussian and top hat blurs are applied to the simulated transmission ratio profiles in order to account for the motion blurring and imaging slit resolution of the experimental measurement. Comparisons between the simulated transmission ratios and the radiograph data lineouts are iterated until a reasonable backlighter profile is obtained. This backlighter profile is combined with the blurred, simulated transmission ratios to obtain simulated intensity profiles that can be directly compared with the radiograph data. Examples will be shown from recent convergent ablation (backlit implosion) experiments at the NIF.

Assembly of high-areal-density deuterium-tritium fuel from indirectly driven cryogenic implosions

The National Ignition Facility has been used to compress deuterium-tritium to an average areal density of ~1.0±0.1 g cm(-2), which is 67% of the ignition requirement. These conditions were obtained using 192 laser beams with total energy of 1-1.6 MJ and peak power up to 420 TW to create a hohlraum drive with a shaped power profile, peaking at a soft x-ray radiation temperature of 275-300 eV. This pulse delivered a series of shocks that compressed a capsule containing cryogenic deuterium-tritium to a radius of 25-35 μm. Neutron images of the implosion were used to estimate a fuel density of 500-800 g cm(-3).

Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums

We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 μm diameter hot core.

Observation of high soft x-ray drive in large-scale hohlraums at the National Ignition Facility

The first soft x-ray radiation flux measurements from hohlraums using both a 96 and a 192 beam configuration at the National Ignition Facility have shown high x-ray conversion efficiencies of ∼85%-90%. These experiments employed gold vacuum hohlraums, 6.4 mm long and 3.55 mm in diameter, heated with laser energies between 150-635 kJ. The hohlraums reached radiation temperatures of up to 340 eV. These hohlraums for the first time reached coronal plasma conditions sufficient for two-electron processes and coronal heat conduction to be important for determining the radiation drive.

Streaked radiography measurements of convergent ablator performance (invited)

The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other ablator rocket parameters have been measured using a single streaked x-ray radiograph. A regularization technique has been used to determine the ablator density profile ρ(r) at each time step; moments of ρ(r) then provide the areal density, average radius, and mass of the unablated, or remaining, ablator material, with the velocity determined from the time derivative of the average radius. The technique has been implemented on experiments at the OMEGA laser facility.

The first measurements of soft x-ray flux from ignition scale Hohlraums at the National Ignition Facility using DANTE (invited)

The first 96 and 192 beam vacuum Hohlraum target experiments have been fielded at the National Ignition Facility demonstrating radiation temperatures up to 340 eV and fluxes of 20 TW/sr as viewed by DANTE representing an ∼20 times flux increase over NOVA/Omega scale Hohlraums. The vacuum Hohlraums were irradiated with 2 ns square laser pulses with energies between 150 and 635 kJ. They produced nearly Planckian spectra with about 30±10% more flux than predicted by the preshot radiation hydrodynamic simulations. To validate these results, careful verification of all component calibrations, cable deconvolution, and software analysis routines has been conducted. In addition, a half Hohlraum experiment was conducted using a single 2 ns long axial quad with an irradiance of ∼2×10(15) W/cm(2) for comparison with NIF Early Light experiments completed in 2004. We have also completed a conversion efficiency test using a 128-beam nearly uniformly illuminated gold sphere with intensities kept low (at 1×10(14) W/cm(2) over 5 ns) to avoid sensitivity to modeling uncertainties for nonlocal heat conduction and nonlinear absorption mechanisms, to compare with similar intensity, 3 ns OMEGA sphere results. The 2004 and 2009 NIF half-Hohlraums agreed to 10% in flux, but more importantly, the 2006 OMEGA Au Sphere, the 2009 NIF Au sphere, and the calculated Au conversion efficiency agree to ±5% in flux, which is estimated to be the absolute calibration accuracy of the DANTEs. Hence we conclude that the 30±10% higher than expected radiation fluxes from the 96 and 192 beam vacuum Hohlraums are attributable to differences in physics of the larger Hohlraums.

Characterization of Endogenous Ethanol in the Mammal

Ethanol has been isolated from the tissues of several animal species in amounts ranging from 23 to 145 micromole/100 gm of tissue. Intestinal bacterial flora appear to be excluded as a source of this ethanol. Radioactivity from pyruvate-2-C(14) appeared in ethanol after incubation with liver slices; this finding indicates an endogenous synthesis.

Triply differential single ionization of argon: charge effects for positron and electron impact

Triply differential single ionization of Ar by 200 eV positron and electron impact is measured and calculated. For an unequivocal test of kinematic differences, fully differential ejected electron angular distributions are measured using the same experimental apparatus and conditions for both positron and electron impact. The binary/recoil intensity ratios are shown to significantly differ for the two projectiles. These data are used to test theoretical calculations.

Predicting Methadone Maintenance Treatment Outcomes Using the Addiction Severity Index and the MMPI‐2 Content Scales (Negative Treatment Indicators and Cynism Scales)

We studied the ability of the Minnesota Multiphasic Personality Inventory-2 Content Scales (Negative Treatment Indicators [TRT] and Cynicism [CYN]) and the domain scales of the Addiction Severity Index (ASI) in predicting outcome from a methadone maintenance program. Participants were 108 African American males treated in a VA health care outpatient methadone maintenance treatment program and followed for up to 1 year after admission. Dependent variables were 1) length of stay and the percentage of 2) missed medication days, 3) toxicology urine samples free from illicit drugs, 4) full-time employment, 5) attendance at scheduled counseling sessions, and 6) counselor ratings of patient progress. A stepwise linear regression equation indicated that low drug severity scores on the ASI and low scores on percentage of missed medication predicted patients who were clean 1 year later; low scores on the psychological domain of the ASI predicted attendance at counseling sessions; a discriminant function analysis (consisting of percent of missed medication, percentage of clean urines, and ratings of patient progress) successfully predicted patient status (i.e., dropouts vs. "active patients") with 85% accuracy. Although the TRT and CYN were related to some ASI domains, they were not associated with any outcome variable. Results suggest that some ASI scores serve as important indicators of patient progress in methadone maintenance treatment.

Design of a streaked radiography instrument for ICF ablator tuning measurements

A streaked radiography diagnostic has been proposed as a technique to determine the ablator mass remaining in an inertial confinement fusion ignition capsule at peak velocity. This instrument, the "HXRI-5," has been designed to fit within a National Ignition Facility Diagnostic Instrument Manipulator. The HXRI-5 will be built at Sandia National Laboratories (SNL), and initial testing will be done at the SNL Z-Beamlet Facility. In this paper, we will describe the National Ignition Campaign requirements for this diagnostic, the instrument design, and the planned test experiments.

Metabolic syndrome status changes with fitness level change: a retrospective analysis

BACKGROUND

Cardiorespiratory fitness level is inversely related to the incidence of Metabolic Syndrome (MetS). This study examined the effects of changes in cardiorespiratory fitness level on MetS status.

METHODS

Male and female participants in a health enhancement program (n = 212) were clinically examined for changes in their MetS status and estimated aerobic capacity over a 3-year period. Two physical examinations, each including a maximal treadmill stress test, occurred within this time frame. Participants were divided into three groups: Group 1 (n = 103) was composed of individuals who presented with MetS at exam 1 and reversed their MetS disease status by exam 2; Group 2 (n = 75) members presented with MetS at both exams; and Group 3 (n = 34) individuals were MetS-free at exam 1 but acquired MetS by exam 2. The relationships between MetS clinical characteristics at exam 1 and exam 2 and changes in graded exercise test (GXT) duration were contrasted for the three groups.

RESULTS

GXT duration, estimated aerobic capacity (VO(2) max), and MetS characteristics improved significantly in Group 1 (P < 0.01). Group 2 individuals also increased GXT duration (P < 0.05) but showed only nonsignificant improvements (P > 0.05) in clinical characteristics. Group 3 members declined in most MetS characteristics and in estimated VO(2) max (P < 0.05).

CONCLUSIONS

Increases in GXT duration accompanied MetS reversal while declines in GXT duration occurred with MetS acquisition. On an individual basis, these changes in GXT duration may be an indicator of disease status.

Reversal of metabolic syndrome characteristics

BACKGROUND

Metabolic syndrome (MetS) is a constellation of three or more clinical health abnormalities from a list of five and, therefore, can vary significantly in its profile. Successful intervention strategies for preventing or resolving individuals' MetS may benefit from better understanding how specific risk factor profiles influence improvement in syndrome status.

METHODS

A retrospective analysis of clinical records for members participating in a university-based health assessment/fitness center between 1978 and 2003 was undertaken in 2005. First-year and second-year measures of body mass index, triglycerides, high-density lipoproteins, fasting blood glucose, and blood pressure were compared. Prevalence of individual MetS risk markers, as well as deviation from cut-point levels, were compared in members with and without the syndrome and in subgroups of those whose MetS status changed between the two examinations.

RESULTS

Of the 878 members analyzed, 133 (15%) presented with metabolic syndrome at first visit. Within 2 years of participating in a health assessment/fitness center, 42% of the members resolved their MetS status. Elevated triglycerides differentially characterized those participants who did not improve their MetS status, since that risk marker was not prevalent in the reversal group, but was 86% prevalent in the nonreversal group. For those who resolved their MetS status, there was a 33% improvement in triglycerides level.

CONCLUSIONS

While MetS resolution was achieved within 2 years for many participants in this study, it is likely that customized treatment interventions are necessary for those individuals with elevated triglycerides, the chief abnormality for those who did not resolve.

Usefulness of multidetector spiral computed tomography according to age and gender for diagnosis of acute pulmonary embolism

Data from the Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) were evaluated to test the hypothesis that the performance of multidetector computed tomographic (CT) pulmonary angiography and CT venography is independent of a patient's age and gender. In 773 patients with adequate CT pulmonary angiography and 737 patients with adequate CT pulmonary angiography and CT venography, the sensitivity and specificity for pulmonary embolism for groups of patients aged 18 to 59, 60 to 79, and 80 to 99 years did not differ to a statistically significant extent, nor were there significant differences according to gender. Overall, however, the specificity of CT pulmonary angiography was somewhat greater in women, but in men and women, it was > or =93%. In conclusion, the results indicate that multidetector CT pulmonary angiography and CT pulmonary angiography and CT venography may be used with various diagnostic strategies in adults of all ages and both genders.

Longitudinal Modeling of the Relationship between Age and Maximal Heart Rate

PURPOSE

Maximal heart rate (HRmax)-prediction equations based on a person's age are frequently used in prescribing exercise intensity and other clinical applications. Results from various cross-sectional studies have shown a linear decrease in HRmax during exercise with increasing age. However, it is less well established that longitudinal tracking of the same individuals' HRmax as they age exhibits an identical linear relationship. This study examined the longitudinal relationship between age and HRmax during exercise.

METHODS

A retrospective analysis of maximal graded exercise test (GXT) results for members participating in a university-based health-assessment/fitness center between 1978 and 2003 was undertaken in 2006. Records were examined from individuals (N = 132) of both sexes who represented a broad range of age and fitness levels and who had multiple GXT (total N = 908) conducted over 25 years. HRmax-prediction equations based on participants' age and HRmax elicited during the tests were developed using a linear mixed-models statistical analysis approach.

RESULTS

Clinical measurements obtained during the administration of the GXT included in this longitudinal study resulted in the generation of a univariate prediction model: HRmax = 207 - 0.7 x age. Model parameters were highly statistically significant (P < 0.001).

CONCLUSIONS

The relationship between age and HRmax during exercise developed in this longitudinal study has resulted in a prediction equation appreciably different from the conventional HRmax formula (220 - age) often used in exercise prescription, and it confirms findings from recent cross-sectional investigations of HRmax.

Pulmonary embolism and deep venous thrombosis in hospitalized adults with chronic obstructive pulmonary disease

BACKGROUND

Hospitalized patients with exacerbations of chronic obstructive pulmonary disease (COPD), when routinely evaluated for pulmonary embolism (PE), show PE in 25-29% of cases. We assessed the rate of diagnosis of PE and deep venous thrombosis (DVT) in hospitalized patients with COPD and the influence of age on relative risk compared with hospitalized patients who do not have COPD.

METHODS

A retrospective evaluation of data in hospitalized adults with and without COPD from the National Hospital Discharge Survey.

RESULTS

From 1979 to 2003, 58,392,000 adults 20 years of age and older, were hospitalized with COPD in the United States. Among these patients, PE was diagnosed in 381,000 (0.65%) and DVT in 632,000 (1.08%). The relative risk of PE in adults hospitalized with COPD was 1.92 and for DVT it was 1.30. Relative risks were age dependent. Among those aged 20-39 years with COPD, the relative risk of PE was 5.34. Among patients aged 40-59 years, the relative risk of PE decreased to 2.02, and among patients aged 60-79 years the relative risk of PE was 1.23.

CONCLUSION

These data, when compared with the rate of diagnosis of PE in hospitalized patients with exacerbations of COPD, all of whom were evaluated for PE, indicate that PE in patients with COPD is generally underdiagnosed. In young adults, other risk factors in combination with COPD are uncommon, so the contribution of COPD to the risk of PE becomes more apparent than in older patients.

Deep venous thrombosis and pulmonary embolism in hospitalized patients with sickle cell disease

BACKGROUND

As would be expected with a hypercoagulable state, pulmonary embolism (PE) occurs in sickle cell disease (SCD). Its frequency, however, is undetermined, largely because of difficulties in distinguishing it from thrombosis in situ. The prevalence of deep venous thrombosis (DVT) is also undetermined in patients with SCD. Knowing the prevalence of DVT would be an important step in the overall assessment of the risk of PE in these patients.

METHODS

Data from the National Hospital Discharge Survey were assessed.

RESULTS

In patients <age 40 years, 7000 of 1,581,000 (0.44%) with SCD had a discharge diagnosis of PE compared with 59,000 of 48,611,000 (0.12%) of African Americans without SCD. The prevalence of DVT was similar in patients < age 40 with SCD, 7000 of 1,581,000 (0.44%) and in African Americans who did not have SCD, 193,000 of 48,611,000 (0.40%).

CONCLUSION

The high prevalence of apparent PE in patients with SCD, compared with non-SCD African-American patients of the same age and the comparable prevalence of DVT in both groups are compatible with the concept that thrombosis in situ might be present in many. On the other hand, the data suggest that PE is not rare in patients with SCD. This suggests that PE might be an etiologic factor in patients with SCD who develop respiratory symptoms. In such patients, an imaging procedure might be appropriate.

Fatal pulmonary embolism and stroke

Death from pulmonary embolism (PE) in patients with ischemic stroke was determined from the United States Census Bureau's Compressed Mortality File, which is based on all death certificates throughout the United States. Among patients with ischemic stroke who died over a 19-year study period, PE was the listed cause of death in 11,101 of 2,000,963 individuals (0.55%). On the basis of an assumed sensitivity of death certificates for fatal PE of 26.7% to 37.2%, the corrected rate of fatal PE was 1.5% to 2.1%. Death rates from PE in patients with ischemic stroke decreased from 1980 to 1998. A decrease over 2 decades in the rate of deaths from PE in patients with ischemic stroke is compatible with the increasing and effective use of antithrombotic prophylaxis.

Multidetector computed tomography for the diagnosis of coronary artery disease: a systematic review

PURPOSE

The study's purpose was to determine the sensitivity and specificity of contrast-enhanced multidetector computed tomography (CT) for the detection of coronary artery disease.

SUBJECTS AND METHODS

A search of the literature in all languages was performed incorporating both electronic and manual components. Manual reference checks of recent reviews and all original investigations supplemented the electronic searches.

RESULTS

Average sensitivity for patient-based detection of significant (>50% or > or =50%) stenosis was 61 of 64 (95%) with 4-slice CT, 276 of 292 (95%) with 16-slice CT, and 47 of 47 (100%) with 64-slice CT. Average specificity was 84% for 4-slice CT, 84% for 16-slice CT, and 100% for 64-slice CT. The sensitivity for a significant stenosis in evaluable segments was 307 of 372 (83%) with 4-slice CT, 1023 of 1160 (88%) with 16-slice CT, and 165 of 176 (94%) with 64-slice CT. Average specificity was 93% or greater with all multidetector CT. Seventy-eight percent of segments were evaluable with 4-slice CT, 91% with 16-slice CT, and 100% with 64-slice CT. Stenoses in proximal and mid-segments were shown with a higher sensitivity than distal segments. Left main stenosis was identified with high sensitivity with all multidetector CT, but sensitivity in other vessels increased with an increasing number of detectors.

CONCLUSION

Multidetector CT has the potential to be used as a screening test in appropriate patients. Contrast-enhanced 16-slice CT seems to be reasonably sensitive and specific for the detection of significant coronary artery disease but has shortcomings. Preliminary data with 64-slice CT suggest that it is more sensitive and specific.

Pulmonary embolism as a cause of death in patients who died with cancer

Little is known about the frequency of death from pulmonary embolism in patients who die with cancer. We investigated this on the basis of data from death certificates, as listed by the United States Bureau of the Census in the period 1980-1998. Among patients with cancer who died over the 19-year period of study, pulmonary embolism was the listed cause of death in 0.21% (95% confidence interval, [CI] 0.21-0.22%). The frequency of death from pulmonary embolism in patients who died with cancer decreased from 0.39% in 1980 to 0.15% in 1998. Adjustment of the data for the frailty of the diagnosis of fatal pulmonary embolism based on death certificates indicated a likely range of 0.60% to 1.05% for the frequency of death from pulmonary embolism among patients who died with cancer in the period 1980-1998. In conclusion, with modern diagnostic, prophylactic, and therapeutic methods, death from pulmonary embolism in patients who died with cancer was 1% or less.

Incidence of venous thromboembolism in patients hospitalized with cancer

BACKGROUND

There are sparse data on the frequency of venous thromboembolism in patients with various types of cancer. We sought to determine the incidence and relative risk of venous thromboembolism, pulmonary embolism, and deep venous thrombosis in patients with malignancies.

SUBJECTS AND METHODS

The number of patients discharged with a diagnostic code for 19 types of malignancies, pulmonary embolism or deep venous thrombosis from 1979 through 1999 was obtained from the National Hospital Discharge Survey. Patients studied were men and women of all ages and races.

RESULTS

In patients with any of the 19 malignancies studied, 827,000 of 40,787,000 (2.0%) had venous thromboembolism, which was twice the incidence in patients without these malignancies, 6,854,000 of 662,309,000 (1.0 %). The highest incidence of venous thromboembolism was in patients with carcinoma of the pancreas, 51,000 of 1,176,000 (4.3%), and the lowest incidences were in patients with carcinoma of the bladder and carcinoma of the lip, oral cavity or pharynx. The overall incidences of pulmonary embolism and deep venous thrombosis were also twice the rates in noncancer patients. Incidences with cancer were not age dependent. The incidence of venous thromboembolism in patients with cancer began to increase in the late 1980s.

CONCLUSION

Patients with cancer had twice the incidence of venous thromboembolism, pulmonary embolism and deep venous thrombosis as patients without cancer. The incidence of venous thromboembolism, pulmonary embolism and deep venous thrombosis associated with cancer differed according to the type of cancer, was comparable in elderly and younger patients, and increased in the late 1980s and 1990s.

Extreme sensitivity of differential momentum transfer cross sections to target atom initial conditions

Heavy-particle cross sections differential in the momentum transferred to the target are investigated using the classical trajectory Monte Carlo method. With the 3.6 MeV/mu Au(53+) + He system as a test case, it is shown that these cross sections are extremely sensitive to the initial target temperature. In particular, when thermal motion is varied for one of the target's initial momentum components between 0 and 25 K the absolute cross sections vary by orders of magnitude and, in addition, their relative shapes undergo major changes. We find that by setting one of the target's transverse momenta to a temperature of 16 K, previously reported major discrepancies between theory and experiment are removed.

Mortality from acute pulmonary embolism according to season

BACKGROUND

Varying observations have been made on seasonal differences of mortality from acute pulmonary embolism (PE).

METHODS

The number of deaths each year from PE, from 1980 through 1998, based on death certificates, was obtained from the US National Center for Health Statistics Multiple Cause-of-Death Files.

RESULTS

Acute PE as the cause of death ranged from 0.91 to 1.03 PE deaths per quarter per 100,000 population. Small differences were statistically significant due to the large number of patients evaluated. Quarterly mortality rates from PE in the northeast, south, midwest, and west, where seasonal weather varies widely, showed no meaningful seasonal differences.

CONCLUSION

Mortality rates from PE do not vary to a meaningful extent according to season.

Venous thromboembolism in patients with ischemic and hemorrhagic stroke

The rates of pulmonary embolism (PE), deep venous thrombosis (DVT), and their combination, venous thromboembolism (VTE), in hospitalized patients with stroke from 1979 to 2003 were determined from the National Hospital Discharge Survey. Of 14,109,000 patients hospitalized with ischemic stroke, PE occurred in 72,000 (0.51%), DVT in 104,000 (0.74%), and VTE in 165,000 (1.17%). Of 1,606,000 patients hospitalized with hemorrhagic stroke, rates were higher: PE occurred in 11,000 (0.68%), DVT in 22,000 (1.37%), and VTE in 31,000 (1.93%). The rates of VTE with ischemic stroke and with hemorrhagic stroke did not change over the 25-year period of observation.

Usefulness of 4-, 8-, and 16-slice computed tomography for detection of graft occlusion or patency after coronary artery bypass grafting

The sensitivity and specificity of computed tomographic angiography for the evaluation of coronary artery bypass grafts (CABGs) was reviewed. A search of published studies in all languages was performed, incorporating electronic and manual components. A total of 985 patients with 2,200 CABGs participated in investigations with single-detector computed tomography (CT), 441 patients (1,246 CABGs) with 4-slice CT, none with 8-slice CT, and 144 patients (416 grafts) with 16-slice CT. Pooled data showed a sensitivity for the detection of complete occlusion with single-slice CT of 81% (402 of 494 patients), with 4-slice CT of 93% (293 of 315 patients), and with 16-slice CT of 99% (75 of 76 patients). The specificity, based on pooled data, using single-slice CT was 89% (1,507 of 1,697 patients), with 4-slice CT was 96% (878 of 915 patients), and with 16-slice CT was 98% (301 of 306 patients). The detection of complete occlusion and the detection of patency in saphenous vein bypass grafts and arterial bypass grafts were similar with multislice CT. Limited data were available on the detection of significant stenosis, exclusive of complete occlusion. With 4-slice CT, the sensitivity was 74% (23 of 31 patients) and was 88% (21 of 24 patients) with 16-slice CT. In conclusion, single-detector CT was able to detect graft patency, but it was not sensitive for graft occlusion. The data suggest that 4- and 16-slice CT can be used for the detection of complete graft occlusion or graft patency of CABGs. Significant stenosis was better assessed with 16-slice CT than with 4-slice CT.

Obesity as a risk factor in venous thromboembolism

PURPOSE

Whether obesity is an independent risk factor for pulmonary embolism or deep venous thrombosis has not been fully determined.

METHODS

We used the database of the National Hospital Discharge Survey to further investigate the potential risk of obesity in venous thromboembolic disease.

RESULTS

The relative risk of deep venous thrombosis, comparing obese patients with non-obese patients, was 2.50 (95% confidence interval [CI] = 2.49-2.51). The relative risk of pulmonary embolism was 2.21 (95% CI = 2.20-2.23). Obese females had a greater relative risk for deep venous thrombosis than obese males, 2.75 (95% CI = 2.74-2.76) versus 2.02 (95% CI = 2.01-2.04). Obesity had the greatest impact on both men and women aged less than 40 years.

CONCLUSION

The data indicate that obesity is a risk factor for venous thromboembolic disease in men as well as women.

Trends in the incidence of pulmonary embolism and deep venous thrombosis in hospitalized patients

Trends in the incidences of pulmonary embolism (PE), deep venous thrombosis (DVT), and venous thromboembolism (VTE) (PE or DVT, or both) in hospitalized adults (aged > or =20 years) were evaluated using data from the National Hospital Discharge Survey. From 1979 to 1999, the incidence of DVT in hospitalized patients increased from 0.8% of admissions to 1.3% of admissions. The incidence of PE was 0.4% of admissions and did not change over the 21-year period. Trends and incidences were similar or the same among men and women and whites and blacks.

Venous thromboembolism according to age: the impact of an aging population

BACKGROUND

With the aging of the US population, there is concern that the rate of venous thromboembolism will increase, thereby increasing the health burden. In this study we sought to determine trends in the diagnosis of deep venous thrombosis (DVT) and pulmonary embolism (PE) in the elderly as well as the use of diagnostic tests.

METHODS

Data from the National Hospital Discharge Survey were used. These data are abstracted each year from a sample of records of patients discharged from non-federal short-stay hospitals in the entire United States. Main outcome measures were trends in rates of diagnosis of DVT and PE as well as trends in the use of diagnostic tests between 1979 and 1999.

RESULTS

The rates of diagnosis of DVT and PE and of the use of diagnostic tests over 21 years were markedly higher in elderly than in younger patients (P<.001). Although the rate of diagnosed DVT in elderly patients strikingly increased over the past decade (P< .001), that of PE has been relatively constant. There was a proportionately greater use of venous ultrasonography, ventilation-perfusion lung scanning, and pulmonary angiography in elderly than in younger patients.

CONCLUSIONS

Extensive use of diagnostic tests in elderly patients in the past decade has resulted in an increased diagnostic rate for DVT but not PE. The reason for this disparity is uncertain but may reflect early diagnosis and treatment of DVT. With the aging of the population, DVT will increase the health burden.

Outcome and complications of retrievable inferior vena cava filters

The results and risks of retrievable inferior vena cava filters were reviewed. Systematic review identified 6 prospective case series with broad ranges of indications for filters. In these case series, 4 different types of retrievable filters were inserted in 284 patients. The longest reported duration of insertion was 134 days. Among patients in whom percutaneous removal of the filter was attempted, the filter was successfully removed in 144 of 159 (91%). Surgery was necessary to remove the filter from 1 patient (1%), and filters could not be removed because of large trapped thrombi in 14 patients (9%).

Pulmonary Thromboembolism in American Indians and Alaskan Natives

BACKGROUND

The rate of diagnosis of deep venous thrombosis and/or pulmonary embolism (collectively, venous thromboembolism: VTE) among patients discharged from Indian Health Service hospital care from 1980 through 1996 was considerably lower than rates reported in African Americans or whites. Expansion of the national census in 1990 to include American Indians and Alaskan Natives permits a more in-depth examination of this issue.

METHODS

Combined data from the National Hospital Discharge Survey (nonfederal hospitals) and the Indian Health Service (federal hospitals) from 1996 through 2001 were used to evaluate the rate of diagnosis of VTE in American Indians and Alaskan Natives.

RESULTS

The diagnosis of VTE in American Indians and Alaskan Natives, based on combined data from the National Hospital Discharge Survey and the Indian Health Service was 71 per 100,000 per year compared with 155 per 100,000 per year in African Americans (P<.001) and 131 per 100,000 per year in whites (P<.001). The rate ratio comparing the rate of diagnosis of VTE in American Indians and Alaskan Natives with African Americans was 0.46 (95% confidence interval, 0.45-0.47) and comparing American Indians and Alaskan Natives with whites it was 0.54 (95% confidence interval, 0.53-0.55).

CONCLUSIONS

The observed relatively low incidence of VTE in American Indians and Alaskan Natives would seem to be due to as yet undetermined genetic factors. The possibility that American Indians and Alaskan Natives have different lifestyles that affect the rate of diagnosis of VTE cannot be excluded.

Twenty-one-year trends in the use of inferior vena cava filters

BACKGROUND

Improved inferior vena cava (IVC) filters have led to liberalization of the indications for insertion. Increased use, however, has been followed with a potential for unwarranted insertion. There are only sparse data on trends in the use of IVC filters in patients with pulmonary embolism (PE), patients with deep venous thrombosis (DVT) alone, and patients at high risk. We analyzed the National Hospital Discharge Survey (NHDS) database for such trends.

METHODS

We used data from the NHDS, which is based on a national probability sample of discharges from short-stay nonfederal hospitals in 50 states and the District of Columbia. The numbers of sampled patients with DVT, PE, and IVC filters were determined from the International Classification of Diseases, Ninth Revision, Clinical Modification codes at discharge.

RESULTS

The number of patients who had IVC filters increased from 2000 in 1979 to 49 000 in 1999. In 1999, 45% of IVC filter insertions were in patients with DVT alone, 36% were in patients with PE, and 19% were in patients who presumably were at high risk but did not have DVT or PE listed as a discharge code. The use of IVC filters was more frequent in northeastern states than in western states (P =.01).

CONCLUSIONS

The use of IVC filters increased markedly during the last 2 decades in patients with PE, patients with DVT alone, and patients at risk who had neither PE nor DVT. Randomized controlled trials may lead to improved risk stratification and limit the number of unnecessary filter insertions.

Trends in the use of diagnostic imaging in patients hospitalized with acute pulmonary embolism

From 1979 to 2001, the proportion of imaging tests by computed tomography (CT), ventilation perfusion (VQ) lung scan, pulmonary angiography, and venous ultrasound was assessed in patients with pulmonary embolism (PE) from the National Hospital Discharge Survey. By 2001, there was a higher proportion of imaging tests with CT than VQ scans (36% vs 32%). Even so, in the United States, a large proportion of patients continued to have VQ scans.

Regional differences in rates of diagnosis and mortality of pulmonary thromboembolism

The rates of diagnosis of deep venous thrombosis, pulmonary embolism (PE), and venous thromboembolism (PE and/or deep venous thrombosis) and the mortality rate of PE in hospitalized patients were evaluated in 4 regions of the United States. Data are from the National Hospital Discharge Survey and the United States Bureau of the Census. The western region of the United States showed a lower rate of diagnosis of deep venous thrombosis and venous thromboembolism and a lower mortality rate of PE than any other region.

Estimated case fatality rate of pulmonary embolism, 1979 to 1998

Trends in the estimated case fatality rate of pulmonary embolism (PE) in the United States were obtained from the Bureau of the Census Compressed Mortality File and the National Hospital Discharge Survey. The estimated case fatality rate of PE increased from 1979 to 1989, then decreased through 1998. It increased exponentially with age and was higher in African-American than Caucasian patients (rate ratio 1.42; 95% confidence interval 1.40 to 1.44). The declining population mortality rate of PE from 1979 to 1989 appears to be due to a decreased incidence of PE, reflective of improved prophylaxis, whereas the continued declining population mortality rate of PE through 1998 reflects a decreased case fatality rate due to earlier and better management.

D-dimer for the exclusion of acute venous thrombosis and pulmonary embolism: a systematic review

BACKGROUND

Despite extensive literature, the diagnostic role of d-dimer for deep venous thrombosis (DVT) or pulmonary embolism (PE) remains unclear, reflecting multiple d-dimer assays and concerns about differing sensitivities and variability.

PURPOSE

To systematically review trials that assessed sensitivity, specificity, likelihood ratios, and variability among d-dimer assays.

DATA SOURCES

Studies in all languages were identified by searching PubMed from 1983 to January 2003 and EMBASE from 1988 to January 2003.

STUDY SELECTION

The researchers selected prospective studies that compared d-dimer with a reference standard. Studies of high methodologic quality were included in the primary analyses; sensitivity analysis included additional weaker studies.

DATA EXTRACTION

Two authors collected data on study-level factors: d-dimer assay used, cutoff value, and whether patients had suspected DVT or PE.

DATA SYNTHESIS

For DVT, the enzyme-linked immunosorbent assay (ELISA) and quantitative rapid ELISA dominate the rank order for these values: sensitivity, 0.96 (95% confidence limit [CL], 0.91 to 1.00), and negative likelihood ratio, 0.12 (CL, 0.04 to 0.33); and sensitivity, 0.96 (CL, 0.90 to 1.00), and negative likelihood ratio, 0.09 (CL, 0.02 to 0.41), respectively. For PE, the ELISA and quantitative rapid ELISA also dominate the rank order for these values: sensitivity, 0.95 (CL, 0.85 to 1.00), and negative likelihood ratio, 0.13 (CL, 0.03 to 0.58); and sensitivity, 0.95 (CL, 0.83 to 1.00), and negative likelihood ratio, 0.13 (CL, 0.02 to 0.84), respectively. The ELISA and quantitative rapid ELISA have negative likelihood ratios that yield a high certainty for excluding DVT or PE. The positive likelihood values, which are in the general range of 1.5 to 2.5, do not greatly increase the certainty of diagnosis. Sensitivity analyses do not affect these findings.

LIMITATIONS

Although many studies evaluated multiple d-dimer assays, findings are based largely on indirect comparisons of test performance characteristics across studies.

CONCLUSION

The ELISAs in general dominate the comparative ranking among the d-dimer assays for sensitivity and negative likelihood ratio. For excluding PE or DVT, a negative result on quantitative rapid ELISA is as diagnostically useful as a normal lung scan or negative duplex ultrasonography finding.

Pulmonary thromboembolism in Asians/Pacific Islanders in the United States: analysis of data from the National Hospital Discharge Survey and the United States Bureau of the Census

PURPOSE

To assess the rate of diagnosis of deep venous thrombosis, pulmonary embolism, and venous thromboembolism; the incidence in hospitalized patients; and mortality from pulmonary embolism among Asians/Pacific Islanders in the United States.

METHODS

The number of patients discharged from hospitals with a diagnostic code for pulmonary embolism or deep venous thrombosis from 1990 through 1999 was obtained from the National Hospital Discharge Survey. Population estimates and deaths from pulmonary embolism from 1990 through 1998 were obtained from the United States Bureau of the Census.

RESULTS

Rate ratios of 10-year age-adjusted rates of diagnosis of deep venous thrombosis, pulmonary embolism, and venous thromboembolism comparing Asians/Pacific Islanders with whites and African Americans ranged from 0.16 to 0.21. Rate ratios comparing incidences in hospitalized patients ranged from 0.32 to 0.42. The age-adjusted rate ratio of mortality in "others" (which included Asians/Pacific Islanders) was 0.29 (95% confidence interval [CI]: 0.01 to 0.87) compared with whites and 0.14 (95% CI: 0.0 to 0.58) compared with African Americans.

CONCLUSION

Rates of deep venous thrombosis, pulmonary embolism, and venous thromboembolism; incidences in hospitalized patients; and the mortality rate from pulmonary embolism were markedly lower in Asians/Pacific Islanders than in whites and African Americans. Clinical assessment of the prior probability of venous thromboembolic disease at the bedside should probably be adjusted based on these ethnic differences.

Analysis of occurrence of venous thromboembolic disease in the four seasons

Reports of seasonal variation of the incidence of pulmonary embolism and deep venous thrombosis are inconsistent as to when or if it occurs. We used data from the National Hospital Discharge Survey and the United States (US) Bureau of the Census to test for circannual variation throughout the entire US and in regions of the US over a period of 21 years. Pulmonary embolism, deep venous thrombosis, or the combination did not show seasonal variation in the US or in any region of the US, including the Southern region, where winters are mild, and the northeastern and midwestern regions, where seasons are sharply defined.