372 research outputs found
Is NIPPV Superior to CPAP in Maintaining Targeted Oxygen Saturation Ranges in Preterm Infants on Moderate Non-Invasive Respiratory Support?
Background: Non-invasive positive pressure ventilation (NIPPV) and continuous positive airway pressure (CPAP) are non-invasive respiratory supports commonly used in preterm infants. There is conflicting data on the superiority between these two modes of non-invasive respiratory support. The objective of this study was to determine if oxygen saturation is more within the target range on NIPPV compared to CPAP using the data from histograms.
Methods: Retrospective analysis of premature neonates (\u3c 1500 grams, gestational age \u3c 30 weeks) admitted to the NICU for which oxygen saturation histogram data was available one day before and after the transition between NIPPV and CPAP. FiO2 at the time of data collection was greater than 21 percent. This histogram data, the percentage of time spent in certain SpO2 ranges, was compared before and after the de-escalation from NIPPV to CPAP or escalation from CPAP to NIPPV. FiO2 was additionally compared between the two modes of respiratory support.
Results: A total of 26 infants were included. The median gestational age was 25.5 weeks and the median weight of the infants was 792 grams. Among the 26 infants, there were 34 episodes of transition between NIPPV and CPAP, 19 switches from NIPPV to CPAP, and 15 from CPAP to NIPPV. The percentage of time that oxygen saturation was within the target range (89-94 %) was not statistically significant between the two modes of respiratory support (CPAP 39.9% vs. NIPPV 43.9%, p=0.09) (Table 1). The percentage of time that oxygen saturation was between 86-88% was higher on NIPPV and the percentage of time that oxygen saturation was \u3e94% was higher on CPAP. There was a trend towards lower FiO2 on NIPPV compared to CPAP. When switched from NIPPV to CPAP, there was a higher percentage of time spent above the target range ( \u3e94%) while on CPAP (56% vs 49%, p=0.001), and below the target range (86-88%) while on NIPPV (5.0% vs 1.4%, p=0.02) (Table 3). When switched from CPAP to NIPPV, there was no difference in oxygen saturation ranges (Table 2).
Conclusion: Target oxygen saturation ranges on histogram data were similar in premature infants when supported on CPAP and NIPPV. However, oxygen saturation below the target range was more frequent on NIPPV compared to CPAP. NIPPV is not superior to CPAP in maintaining oxygen saturation within the target range in premature infants on moderate non-invasive respiratory support. The potential risk of low oxygen saturation range while supported on NIPPV in preterm infants requires further research.https://jdc.jefferson.edu/pulmcritcareposters/1003/thumbnail.jp
Effectiveness of Transmitted Drug Resistance Testing Before Initiation of Antiretroviral Therapy in HIV-Positive Individuals
BACKGROUND
For people living with HIV, major guidelines in high-income countries recommend testing for transmitted drug resistance (TDR) to guide the choice of first-line antiretroviral therapy (ART). However, individuals who fail a first-line regimen can now be switched to one of several effective regimens. Therefore, the virological and clinical benefit of TDR testing needs to be evaluated.
METHODS
We included individuals from the HIV-CAUSAL Collaboration who enrolled <6 months of HIV diagnosis between 2006 and 2015, were ART-naive, and had measured CD4 count and HIV-RNA. Follow-up started at the date when all inclusion criteria were first met (baseline). We compared 2 strategies: (1) TDR testing within 3 months of baseline versus (2) no TDR testing. We used inverse probability weighting to estimate the 5-year proportion and hazard ratios (HRs) of virological suppression (confirmed HIV-RNA <50 copies/mL), and of AIDS or death under both strategies.
RESULTS
Of 25,672 eligible individuals (82% males, 52% diagnosed in 2010 or later), 17,189 (67%) were tested for TDR within 3 months of baseline. Of these, 6% had intermediate- or high-level TDR to any antiretroviral drug. The estimated 5-year proportion virologically suppressed was 77% under TDR testing and 74% under no TDR testing; HR 1.06 (95% confidence interval: 1.03 to 1.19). The estimated 5-year risk of AIDS or death was 6% under both strategies; HR 1.03 (95% confidence interval: 0.95 to 1.12).
CONCLUSIONS
TDR prevalence was low. Although TDR testing improved virological response, we found no evidence that it reduced the incidence of AIDS or death in first 5 years after diagnosis
Model of C-Axis Resistivity of High-\Tc Cuprates
We propose a simple model which accounts for the major features and
systematics of experiments on the -axis resistivity, , for \lsco,
\ybco and \bsco . We argue that the -axis resistivity can be separated
into contributions from in-plane dephasing and the -axis ``barrier''
scattering processes, with the low temperature semiconductor-like behavior of
arising from the suppression of the in-plane density of states
measured by in-plane magnetic Knight shift experiments. We report on
predictions for in impurity-doped \ybco materials.Comment: 10 pages + figures, also see March Meeting J13.1
Preheating in an Expanding Universe: Analytic Results for the Massless Case
Analytic results are presented for preheating in both flat and open models of
chaotic inflation, for the case of massless inflaton decay into further
inflaton quanta. It is demonstrated that preheating in both these cases closely
resembles that in Minkowski spacetime. Furthermore, quantitative differences
between preheating in spatially-flat and open models of inflation remain of
order for the chaotic inflation initial conditions considered here.Comment: 15pp, revtex. No figures. Very minor revisions; forthcoming in Phys
Rev
Sequential design of computer experiments for the estimation of a probability of failure
This paper deals with the problem of estimating the volume of the excursion
set of a function above a given threshold,
under a probability measure on that is assumed to be known. In
the industrial world, this corresponds to the problem of estimating a
probability of failure of a system. When only an expensive-to-simulate model of
the system is available, the budget for simulations is usually severely limited
and therefore classical Monte Carlo methods ought to be avoided. One of the
main contributions of this article is to derive SUR (stepwise uncertainty
reduction) strategies from a Bayesian-theoretic formulation of the problem of
estimating a probability of failure. These sequential strategies use a Gaussian
process model of and aim at performing evaluations of as efficiently as
possible to infer the value of the probability of failure. We compare these
strategies to other strategies also based on a Gaussian process model for
estimating a probability of failure.Comment: This is an author-generated postprint version. The published version
is available at http://www.springerlink.co
Large Anomalous Hall effect in a silicon-based magnetic semiconductor
Magnetic semiconductors are attracting high interest because of their
potential use for spintronics, a new technology which merges electronics and
manipulation of conduction electron spins. (GaMn)As and (GaMn)N have recently
emerged as the most popular materials for this new technology. While Curie
temperatures are rising towards room temperature, these materials can only be
fabricated in thin film form, are heavily defective, and are not obviously
compatible with Si. We show here that it is productive to consider transition
metal monosilicides as potential alternatives. In particular, we report the
discovery that the bulk metallic magnets derived from doping the narrow gap
insulator FeSi with Co share the very high anomalous Hall conductance of
(GaMn)As, while displaying Curie temperatures as high as 53 K. Our work opens
up a new arena for spintronics, involving a bulk material based only on
transition metals and Si, and which we have proven to display a variety of
large magnetic field effects on easily measured electrical properties.Comment: 19 pages with 5 figure
The Open Universe Grishchuk-Zel'dovich Effect
The Grishchuk--Zel'dovich effect is the contribution to the microwave
background anisotropy from an extremely large scale adiabatic density
perturbation, on the standard hypothesis that this perturbation is a typical
realization of a homogeneous Gaussian random field. We analyze this effect in
open universes, corresponding to density parameter with no
cosmological constant, and concentrate on the recently discussed
super-curvature modes. The effect is present in all of the low multipoles of
the anisotropy, in contrast with the case where only the
quadrupole receives a contribution. However, for no value of can a
very large scale perturbation generate a spectrum capable of matching
observations across a wide range of multipoles. We evaluate the magnitude of
the effect coming from a given wavenumber as a function of the magnitude of the
density perturbation, conveniently specified by the mean-square curvature
perturbation. From the absence of the effect at the observed level, we find
that for , a curvature perturbation of order unity is
permitted only for inverse wavenumbers more than one thousand times the size of
the observable universe. As tends to one, the constraint weakens to
the flat space result that the inverse wavenumber be more than a hundred times
the size of the observable universe, whereas for it becomes
stronger. We explain the physical meaning of these results, by relating them to
the correlation length of the perturbation. Finally, in an Appendix we consider
the dipole anisotropy and show that it always leads to weaker constraints.Comment: 10 pages LaTeX file (using RevTeX), plus 4 postscript figures to be
printed separately. Final version, to appear in Physical Review D: main
change is a new appendix on the dipole anisotrop
Post-Inflation Reheating in an Expanding Universe
An analytic means of studying the resonant decay of the inflaton field is
developed for the case of background expansion, . It is shown that
the parametric resonance in the inflaton's decay need not disappear when the
expansion of the universe is taken into account, although the total number of
particles produced is fewer than in the case.Comment: 18pp. Plain LaTeX; no figures. Final revised version. To appear in
Physical Review D, 15 February 199
Gemcitabine based combination chemotherapy in advanced pancreatic cancer-indirect comparison
<p>Abstract</p> <p>Background</p> <p>Recent meta-analyses have found a survival advantage with gemcitabine based combinations over single agent gemcitabine in patients with advanced pancreatic cancer. There is paucity of evidence in the form of direct head-to-head randomised controlled trials to determine which combinations are to be preferred.</p> <p>Method</p> <p>Using the adjusted indirect comparison method proposed by Bucher et al, we have assessed randomised controlled trials of four gemcitabine based combinations namely gemcitabine plus a platinum compound or 5-fluorouracil or irinotecan or capecitabine.</p> <p>Results</p> <p>No particular combination was significantly superior to another, but the indirect evidence suggests some important trends.</p> <p>Conclusion</p> <p>The strongest trends on indirect comparison are towards favouring gemcitabine plus capecitabine or gemcitabine plus a platinum compound over gemcitabine plus irinotecan, and to a lesser degree, over gemcitabine plus 5-fluorouracil.</p
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