214 research outputs found
Readmission following pancreatectomy: what can be improved?
AbstractBackgroundReadmissions after pancreatectomy, largely for the management of complications, may also occur as a result of failure to thrive or for diagnostic endeavours. Potential mechanisms to reduce readmission rates may be elucidated by assessing the adequacy of the initial disposition and the real necessity for readmission.MethodsUsing previously identified categories of readmission following pancreatectomy, details of reasons for and results of readmissions were scrutinized using a root cause analysis approach.ResultsOf 658 patients subjected to pancreatectomy between 2001 and 2010, 121 (18%) were readmitted within 30 days. The clinical course in 30% of readmitted patients was found to deviate from the pathway assumed on the initial admission. Patients were readmitted at a median of 9 days (range: 1–30 days) after initial discharge and had a median readmission length of stay of 7 days (mode = 4). Postoperative complications accounted for most readmissions (n = 77, 64%); 17 patients (14%) were readmitted for failure to thrive and 16 (13%) for diagnostics. Root cause analysis detailed subtextual reasons for readmission, including, for example, the initiation of new medications that could potentially have been ordered in an outpatient setting.ConclusionsMore than one quarter of readmissions after pancreatectomy occurred in the setting of failure to thrive or for diagnostic evaluation alone. Root cause analysis revealed potentially avoidable readmissions. The development of a system for stratifying patients at risk for readmission or the failure of the initial disposition, along with an alternative means of efficiently evaluating patients in an outpatient setting, could limit unnecessary readmissions and resource utilization
Foregut Surgery in the Modern Era: A National Survey
Background: Foregut surgery is technically complex. In recent years, increasing attention has been paid to high-stakes surgery outcomes, including mortality and complications. In addition, the use of advanced technology including minimally invasive approaches has been introduced. The current study aims to determine national trends in utilization and outcomes of potentially curative cancer resections of the foregut, including esophagus, stomach, liver, and pancreas.
Methods: The Nationwide Inpatient Sample was queried to identify all esophageal, gastric, liver and pancreas resections performed for cancer during 1998-2009. Annual incidence, major in-hospital postoperative complications, length of stay and in-hospital mortality were evaluated. Univariate and multivariate analysis performed by chi square and logistic regression. For all comparisons, p-values
Results: 298,871 patients (nationally-weighted) underwent cancer directed foregut surgery 1998-2009. Of those 19,002 (6%) were esophagectomies, 123,198 (41%) were gastrectomies, 62,313 (21%) were hepatectomies and 94,358 (32%) were pancreatectomies. From early years (1998-2000) to late years (2007-2009) use of laparoscopy in foregut surgery increased from 3% to 5%. Laparoscopy in esophagectomy increased the most from 1% to 5%, while its use in hepatectomy remained unchanged at 4%. Gastrectomy and pancreatectomy involving minimally invasive techniques increased from 2% to 5% and 5% to 6%, respectively. For all four foregut surgery types, patient comorbidities increased over time; patients with ≥2 major comorbidities increased from 53% to 64%. Conversely, patient mortality and length of stay (LOS) decreased over time. However, we observed an increase in complications for all sites combined from 22.8% to 24.4%. Laparoscopy was not significantly associated with decreased complications, but was associated with lower mortality when compared to open resection alone 3.1% vs. 5%. Independent predictors of increased complications included older age, gender, higher comorbidity, hospital volume. Older age, male sex, higher comorbidity, low volume center and non-use of laparoscopy were independent predictors of in-hospital mortality.
Conclusion: Foregut surgery in the modern era is being increasingly deployed on sicker patients. While decreased in-hospital mortality and LOS are commendable, complication rates remain substantial and nondecreasing. Minimally invasive techniques have minor but increasing penetrance in foregut surgery. Our results suggest comparable advances and potential pitfalls among major types of foregut surgery in the current era
Genome-wide profiles of CtBP link metabolism with genome stability and epithelial reprogramming in breast cancer
epithelial reprogramming in breast cance
Dynamical Mass Measurement of the Young Spectroscopic Binary V343 Normae AaAb Resolved With the Gemini Planet Imager
We present new spatially resolved astrometry and photometry from the Gemini
Planet Imager of the inner binary of the young multiple star system V343
Normae, which is a member of the beta Pictoris moving group. V343 Normae
comprises a K0 and mid-M star in a ~4.5 year orbit (AaAb) and a wide 10" M5
companion (B). By combining these data with archival astrometry and radial
velocities we fit the orbit and measure individual masses for both components
of M_Aa = 1.10 +/- 0.10 M_sun and M_Ab = 0.290 +/- 0.018 M_sun. Comparing to
theoretical isochrones, we find good agreement for the measured masses and JHK
band magnitudes of the two components consistent with the age of the beta Pic
moving group. We derive a model-dependent age for the beta Pic moving group of
26 +/- 3 Myr by combining our results for V343 Normae with literature
measurements for GJ 3305, which is another group member with resolved binary
components and dynamical masses.Comment: 12 pages, 7 figures. Accepted to A
Automated data processing architecture for the Gemini Planet Imager Exoplanet Survey
The Gemini Planet Imager Exoplanet Survey (GPIES) is a multi-year direct
imaging survey of 600 stars to discover and characterize young Jovian
exoplanets and their environments. We have developed an automated data
architecture to process and index all data related to the survey uniformly. An
automated and flexible data processing framework, which we term the Data
Cruncher, combines multiple data reduction pipelines together to process all
spectroscopic, polarimetric, and calibration data taken with GPIES. With no
human intervention, fully reduced and calibrated data products are available
less than an hour after the data are taken to expedite follow-up on potential
objects of interest. The Data Cruncher can run on a supercomputer to reprocess
all GPIES data in a single day as improvements are made to our data reduction
pipelines. A backend MySQL database indexes all files, which are synced to the
cloud, and a front-end web server allows for easy browsing of all files
associated with GPIES. To help observers, quicklook displays show reduced data
as they are processed in real-time, and chatbots on Slack post observing
information as well as reduced data products. Together, the GPIES automated
data processing architecture reduces our workload, provides real-time data
reduction, optimizes our observing strategy, and maintains a homogeneously
reduced dataset to study planet occurrence and instrument performance.Comment: 21 pages, 3 figures, accepted in JATI
Characterizing 51 Eri b from 1-5 m: a partly-cloudy exoplanet
We present spectro-photometry spanning 1-5 m of 51 Eridani b, a 2-10
M planet discovered by the Gemini Planet Imager Exoplanet Survey.
In this study, we present new (1.90-2.19 m) and (2.10-2.40
m) spectra taken with the Gemini Planet Imager as well as an updated
(3.76 m) and new (4.67 m) photometry from the NIRC2 Narrow
camera. The new data were combined with (1.13-1.35 m) and
(1.50-1.80 m) spectra from the discovery epoch with the goal of better
characterizing the planet properties. 51 Eri b photometry is redder than field
brown dwarfs as well as known young T-dwarfs with similar spectral type
(between T4-T8) and we propose that 51 Eri b might be in the process of
undergoing the transition from L-type to T-type. We used two complementary
atmosphere model grids including either deep iron/silicate clouds or
sulfide/salt clouds in the photosphere, spanning a range of cloud properties,
including fully cloudy, cloud free and patchy/intermediate opacity clouds.
Model fits suggest that 51 Eri b has an effective temperature ranging between
605-737 K, a solar metallicity, a surface gravity of (g) = 3.5-4.0 dex,
and the atmosphere requires a patchy cloud atmosphere to model the SED. From
the model atmospheres, we infer a luminosity for the planet of -5.83 to -5.93
(), leaving 51 Eri b in the unique position as being one of
the only directly imaged planet consistent with having formed via cold-start
scenario. Comparisons of the planet SED against warm-start models indicates
that the planet luminosity is best reproduced by a planet formed via core
accretion with a core mass between 15 and 127 M.Comment: 27 pages, 19 figures, Accepted for publication in The Astronomical
Journa
GPI spectra of HR 8799 c, d, and e from 1.5 to 2.4m with KLIP Forward Modeling
We explore KLIP forward modeling spectral extraction on Gemini Planet Imager
coronagraphic data of HR 8799, using PyKLIP and show algorithm stability with
varying KLIP parameters. We report new and re-reduced spectrophotometry of HR
8799 c, d, and e in H & K bands. We discuss a strategy for choosing optimal
KLIP PSF subtraction parameters by injecting simulated sources and recovering
them over a range of parameters. The K1/K2 spectra for HR 8799 c and d are
similar to previously published results from the same dataset. We also present
a K band spectrum of HR 8799 e for the first time and show that our H-band
spectra agree well with previously published spectra from the VLT/SPHERE
instrument. We show that HR 8799 c and d show significant differences in their
H & K spectra, but do not find any conclusive differences between d and e or c
and e, likely due to large error bars in the recovered spectrum of e. Compared
to M, L, and T-type field brown dwarfs, all three planets are most consistent
with mid and late L spectral types. All objects are consistent with low gravity
but a lack of standard spectra for low gravity limit the ability to fit the
best spectral type. We discuss how dedicated modeling efforts can better fit HR
8799 planets' near-IR flux and discuss how differences between the properties
of these planets can be further explored.Comment: Accepted to AJ, 25 pages, 16 Figure
A Root-Cause Analysis of Mortality Following Major Pancreatectomy
Abstract Introduction Although mortality rates from pancreatectomy have decreased worldwide, death remains an infrequent but profound event at an individual practice level. Root-cause analysis is a retrospective method commonly employed to understand adverse events. We evaluate whether emerging mortality risk assessment tools sufficiently predict and account for actual clinical events that are often identified by root-cause analysis. Methods We assembled a Pancreatic Surgery Mortality Study Group comprised of 36 pancreatic surgeons from 15 institutions in 4 countries. Mortalities after pancreatectomy (30 and 90 days) were accrued from 2000 to 2010. For root-cause analysis, each surgeon "deconstructed" the clinical events preceding a death to determine cause. We next tested whether mortality risk assessment tools (ASA, POSSUM, Charlson, SOAR, and NSQIP) could predict those patients who would die (n=218) and compared their prognostic accuracy against a cohort of resections in which no patient died (n=1,177). Results Two hundred eighteen deaths (184 Whipple's resection, 18 distal pancreatectomies, and 16 total pancreatectomies) were identified from 11,559 pancreatectomies performed by surgeons whose experience averaged 14.5 years. Overall 30-and 90-day mortalities were 0.96% and 1.89%, respectively. Individual surgeon rates ranged from 0% to 4.7%. Only 5 patients died intraoperatively, while the other 213 succumbed at a median of 29 days. Mean patient age was 70 years old (38% were >75 years old). Malignancy was the indication in 90% of cases, mostly pancreatic cancer (57%). Median operative time was 365 min and estimated blood loss was 700 cc (range, 100-16,000 cc). Vascular repair or multivisceral resections were required for 19.7% and 15.1%, respectively. Seventy-seven percent had a variety of major complications before death. Eighty-seven percent required intensive care unit care, 55% were transfused, and 35% were reoperated upon. Fifty percent died during the index admission, while another 11% died after a readmission. Almost half (n=107) expired between 31 and 90 days. Only 11% had autopsies. Operation-related complications contributed to 40% of deaths, with pancreatic fistula being the most evident (14%). Technical errors (21%) and poor patient selection (15%) were cited by surgeons. Of deaths, 5.5% had associated cancer progression-all occurring between 31 and 90 days. Even after root-cause scrutiny, the ultimate cause of death could not be determined for a quarter of the patients-most often between 31 and 90 days. While assorted risk models predicted mortality with variable discrimination from nonmortalities, they consistently underestimated the actual mortality events we report. Conclusion Root-cause analysis suggests that risk prediction should include, if not emphasize, operative factors related to pancreatectomy. While risk models can distinguish between mortalities and nonmortalities in a collective fashion, they vastly miscalculate the actual chance of death on an individual basis. This study reveals the contributions of both comorbidities and aggressive surgical decisions to mortality
Performance of the Gemini Planet Imager Non-Redundant Mask and spectroscopy of two close-separation binaries HR 2690 and HD 142527
The Gemini Planet Imager (GPI) contains a 10-hole non-redundant mask (NRM),
enabling interferometric resolution in complement to its coronagraphic
capabilities. The NRM operates both in spectroscopic (integral field
spectrograph, henceforth IFS) and polarimetric configurations. NRM observations
were taken between 2013 and 2016 to characterize its performance. Most
observations were taken in spectroscopic mode with the goal of obtaining
precise astrometry and spectroscopy of faint companions to bright stars. We
find a clear correlation between residual wavefront error measured by the AO
system and the contrast sensitivity by comparing phase errors in observations
of the same source, taken on different dates. We find a typical 5-
contrast sensitivity of at . We explore the
accuracy of spectral extraction of secondary components of binary systems by
recovering the signal from a simulated source injected into several datasets.
We outline data reduction procedures unique to GPI's IFS and describe a newly
public data pipeline used for the presented analyses. We demonstrate recovery
of astrometry and spectroscopy of two known companions to HR 2690 and HD
142527. NRM+polarimetry observations achieve differential visibility precision
of in the best case. We discuss its limitations on
Gemini-S/GPI for resolving inner regions of protoplanetary disks and prospects
for future upgrades. We summarize lessons learned in observing with NRM in
spectroscopic and polarimetric modes.Comment: Accepted to AJ, 22 pages, 14 figure
Improving and Assessing Planet Sensitivity of the GPI Exoplanet Survey with a Forward Model Matched Filter
We present a new matched filter algorithm for direct detection of point
sources in the immediate vicinity of bright stars. The stellar Point Spread
Function (PSF) is first subtracted using a Karhunen-Lo\'eve Image Processing
(KLIP) algorithm with Angular and Spectral Differential Imaging (ADI and SDI).
The KLIP-induced distortion of the astrophysical signal is included in the
matched filter template by computing a forward model of the PSF at every
position in the image. To optimize the performance of the algorithm, we conduct
extensive planet injection and recovery tests and tune the exoplanet spectra
template and KLIP reduction aggressiveness to maximize the Signal-to-Noise
Ratio (SNR) of the recovered planets. We show that only two spectral templates
are necessary to recover any young Jovian exoplanets with minimal SNR loss. We
also developed a complete pipeline for the automated detection of point source
candidates, the calculation of Receiver Operating Characteristics (ROC), false
positives based contrast curves, and completeness contours. We process in a
uniform manner more than 330 datasets from the Gemini Planet Imager Exoplanet
Survey (GPIES) and assess GPI typical sensitivity as a function of the star and
the hypothetical companion spectral type. This work allows for the first time a
comparison of different detection algorithms at a survey scale accounting for
both planet completeness and false positive rate. We show that the new forward
model matched filter allows the detection of fainter objects than a
conventional cross-correlation technique with a Gaussian PSF template for the
same false positive rate.Comment: ApJ accepte
- …