Thoracic paravertebral blocks (PVBs) are successfully performed for pain management after breast surgery. The aim of the present quantitative systematic review was to assess the efficacy and adverse ...events of PVB in women undergoing breast surgery.
The systematic search, data extraction, critical appraisal, and pooled analysis were performed according to the PRISMA statement. The relative risk (RR), mean difference (MD), and their corresponding 95% confidence intervals (CIs) were calculated using the RevMan® statistical software for dichotomous and continuous outcomes, respectively. Pain scores were converted to a scale ranging from 0 (no pain) to 10 (worst pain).
Fifteen randomized controlled trials (published between 1999 and 2009) including 877 patients met the inclusion criteria. There was a significant difference in worst postoperative pain scores between PVB and general anaesthesia (GA) at <2 h (MD: −2.68; 95% CI: −3.33 to −2.02; P<0.00001), 2–24 h (MD: −2.34; 95% CI: −2.42 to −1.12; P<0.00001), and 24–48 h (MD: −1.75; 95% CI: −3.19 to 0.31; P=0.02). Accordingly, lower pain scores were observed for combined PVB with GA compared with GA alone for <2 h (MD: −1.87; 95% CI: −2.53 to −1.21; P<0.00001), 2–24 h (MD: −2.21; 95% CI: −3.07 to −1.35; P<0.00001), and 24–48 h (MD: −1.80; 95% CI: −2.92 to 0.68; P=0.002). The RR for the reported adverse events (e.g. pneumothorax) was low.
There is considerable evidence that PVB in addition to GA or alone provide a better postoperative pain control with little adverse effects compared with other analgesic treatment strategies.
Aims.Numerous spectroscopic observations provide compelling evidence for a non-canonical mixing process that modifies the surface abundances of Li, C and N of low-mass red giants when they reach the ...bump in the luminosity function. Eggleton and collaborators have proposed that a molecular weight inversion created by the 3He(3He, 2p)4He reaction may be at the origin of this mixing, and relate it to the Rayleigh-Taylor instability. We argue that one is actually dealing with a double diffusive instability referred to as thermohaline convection and we discuss its influence on the red giant branch. Methods.We compute stellar models of various initial metallicities that include thermohaline mixing, which is treated as a diffusive process based on the prescription given originally by Ulrich for the turbulent diffusivity produced by the thermohaline instability in stellar radiation zones. Results.Thermohaline mixing simultaneously accounts for the observed behaviour of the carbon isotopic ratio and of the abundances of Li, C and N in the upper part of the red giant branch. It significantly reduces the 3He production with respect to canonical evolution models as required by measurements of 3He/H in galactic HII regions. Conclusions.Thermohaline mixing is a fundamental physical process that must be included in stellar evolution modeling.
In the present meta-analysis, we assessed the efficacy and safety of intravenous administration of dexmedetomidine (DEX) compared with placebo or opioids for acute postoperative pain treatment in ...adults undergoing surgery. The meta-analysis was performed according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement and the recommendations of the Cochrane Collaboration. Randomized controlled trials investigating perioperative administration of DEX were included. For dichotomous outcomes relative risks (RR; 95% confidence intervals CI) and for continuous outcomes mean differences (MD; 95% CI) were calculated. Twenty-eight randomized controlled trials including 1420 patients were finally included. Patients treated with DEX reported lower postoperative pain intensity (MD1h postoperatively: -1.59U (numeric rating scale: 0 to 10) 95% CI: -2.37 to -0.82; P=.000001) and showed a lower postoperative opioid consumption (MD24h postoperatively: -17.24mg; 95% CI: -24.38 to -10.10; P=.00001) compared with placebo. Additionally, the DEX group showed a lower RR for opioid-related adverse events (e.g. RRNausea (postanesthesia care unit): 0.66; 95% CI: 0.43 to 1.02; P=.06). The most common adverse event in patients treated with DEX was intraoperative bradycardia with a RR of 2.66 (RR: 2.66; 95% CI: 1.54 to 4.58; P=.0004) compared with placebo. There is evidence that DEX administration leads to lower postoperative pain, reduced opioid consumption, and a lower risk for opioid-related adverse events. The comparison of DEX vs opioids for postoperative pain treatment is less clear due to limited data. The most common adverse event was intraoperative bradycardia after DEX administration. Therefore cautions in patients at risk are warranted, and large trials focusing on long-term outcomes after intraoperative DEX use are needed.
Background Approximately 30–80% of postoperative patients complain about moderate to severe post-surgical pain, indicating that postoperative pain treatment is still a problem. Methods We analysed ...prospectively collected data on patients in a university hospital receiving systemic and epidural patient-controlled analgesia and continuous peripheral nerve block (CPNB) documented by the acute pain service team in a computer-based system. Results Of 18 925 patients visited in the postoperative period between 1998 and 2006, 14 223 patients received patient-controlled epidural analgesia (PCEA), 1591 i.v. patient-controlled analgesia (IV-PCA), 1737 continuous brachial plexus block, and 1374 continuous femoral/sciatic nerve block. Mean dynamic and resting pain scores (VAS 0–100) were significantly lower for peripheral or neuroaxial regional analgesia compared with patient-controlled systemic opioid analgesia (P<0.05). The risk of a symptomatic spinal mass lesion including epidural haematoma (0.02%; 1:4741) or epidural abscess (0.014%; 1:7142) after PCEA was 1:2857 (0.04%). Neurological complications after CPNB occurred in two patients who received interscalene brachial plexus block. Conclusions We demonstrated that PCEA, IV-PCA, and CPNB are safe and efficient. Although all of these treatment strategies provide effective analgesia, PCEA and CPNB provided superior pain relief compared with IV-PCA. We demonstrated that serious complications of analgesic techniques are rare but possibly disastrous necessitating a close supervision by an acute pain service. We found a low rate of adverse effects including hypotension and motor impairment and a low incidence of epidural haematoma for thoracic PCEA compared with lumbar PCEA.
Context.We examine the MHD instabilities arising in the radiation zone of a differentially rotating star, in which a poloidal field of fossil origin is sheared into a toroidal field. Aims.We focus on ...the non-axisymmetric instability that affects the toroidal magnetic field in a rotating star, which was first studied by Pitts and Tayler in the non-dissipative limit. If such an instability were able to mix the stellar material, it could have an impact on the evolution of the star. According to Spruit, it could also drive a dynamo. Methods.We compare the numerical solutions built with the 3-dimensional ASH code with the predictions drawn from an analytical study of the Pitts & Tayler instability. Results.The Pitts & Tayler instability is manifestly present in our simulations, with its conspicuous $m=1$ dependence in azimuth. But its analytic treatment used so far is too simplified to be applied to the real stellar situation. Although the instability generated field reaches an energy comparable to that of the mean poloidal field, that field seems unaffected by the instability: it undergoes Ohmic decline, and is neither eroded nor regenerated by the instability. The toroidal field is produced by shearing the poloidal field and it draws its energy from the differential rotation. The small scale motions behave as Alfvén waves; they cause negligible eddy-diffusivity and contribute little to the net transport of angular momentum. Conclusions.In our simulations we observe no sign of dynamo action, of either mean field or fluctuation type, up to a magnetic Reynolds number of 105. However the Pitts & Tayler instability is sustained as long as the differential rotation acting on the poloidal field is able to generate a toroidal field of sufficient strength. But in the Sun such a poloidal field of fossil origin is ruled out by the nearly uniform rotation of the deep interior.
Since 1995, more than 500 extrasolar planets have been discovered orbiting very close to their parent star, where they experience strong tidal interactions. Their orbital evolution depends on the ...physical mechanisms that cause tidal dissipation, and these are still not well understood. We refine the theory of the equilibrium tide in fluid bodies that are partly or entirely convective, to predict the dynamical evolution of the systems. In particular, we examine the validity of modeling the tidal dissipation by the quality factor Q, as is commonly done. We consider here the simplest case where the considered star or planet rotates uniformly, all spins are aligned, and the companion is reduced to a point-mass. The first manifestation of the tide is to distort the shape of the star or planet adiabatically along the line of centers. This generates the divergence-free velocity field of the adiabatic equilibrium tide which is decoupled from the dynamical tide. The tidal kinetic energy is dissipated into heat through turbulent friction, which is modeled here as an eddy-viscosity acting on the adiabatic tidal flow. This dissipation induces a second velocity field, the dissipative equilibrium tide, which is in quadrature with the exciting potential; it is responsible for the imaginary part of the disturbing function, which is implemented in the dynamical evolution equations, from which one derives characteristic evolution times. The rate at which the system evolves depends on the physical properties of tidal dissipation, and specifically on how the eddy viscosity varies with tidal frequency and on the thickness of the convective envelope for the fluid equilibrium tide. At low frequency, this tide retards by a constant time delay, whereas it lags by a constant angle when the tidal frequency exceeds the convective turnover rate.
Context. Rotational splittings are currently measured for several main sequence stars and a large number of red giants with the space mission Kepler. This will provide stringent constraints on ...rotation profiles. Aims. Our aim is to obtain seismic constraints on the internal transport and surface loss of the angular momentum of oscillating solar-like stars. To this end, we study the evolution of rotational splittings from the pre-main sequence to the red-giant branch for stochastically excited oscillation modes. Methods. We modified the evolutionary code CESAM2K to take rotationally induced transport in radiative zones into account. Linear rotational splittings were computed for a sequence of 1.3 M sub(middot in circle) models. Rotation profiles were derived from our evolutionary models and eigenfunctions from linear adiabatic oscillation calculations. Results. We find that transport by meridional circulation and shear turbulence yields far too high a core rotation rate for red-giant models compared with recent seismic observations. We discuss several uncertainties in the physical description of stars that could have an impact on the rotation profiles. For instance, we find that the Goldreich-Schubert-Fricke instability does not extract enough angular momentum from the core to account for the discrepancy. In contrast, an increase of the horizontal turbulent viscosity by 2 orders of magnitude is able to significantly decrease the central rotation rate on the red-giant branch. Conclusions. Our results indicate that it is possible that the prescription for the horizontal turbulent viscosity largely underestimates its actual value or else a mechanism not included in current stellar models of low mass stars is needed to slow down the rotation in the radiative core of red-giant stars.
The aim of this quantitative systematic review was to assess the efficacy and adverse effects of ketamine added to caudal local anaesthetics in comparison with local anaesthetics alone in children ...undergoing urological, lower abdominal, or lower limb surgery.
The systematic search, data extraction, critical appraisal, and pooled data analysis were performed according to the PRISMA statement. All randomized controlled trials (RCTs) were included in this meta-analysis and relative risk (RR), mean difference (MD), and the corresponding 95% confidence intervals (CIs) were calculated using the Revman® statistical software for dichotomous and continuous outcomes.
Thirteen RCTs (published between 1991 and 2008) including 584 patients met the inclusion criteria. There was a significant longer time to first analgesic requirements in patients receiving ketamine in addition to a local anaesthetic compared with a local anaesthetic alone (MD: 5.60 h; 95% CI: 5.45–5.76; P<0.00001). There was a lower RR for the need of rescue analgesia in children receiving a caudal regional anaesthesia with ketamine in addition to local anaesthetics (RR: 0.71; 95% CI: 0.44–1.15; P=0.16).
Caudally administered ketamine, in addition to a local anaesthetic, provides prolonged postoperative analgesia with few adverse effects compared with local anaesthetics alone. There is a clear benefit of caudal ketamine, but the uncertainties about neurotoxicity relating to the dose of ketamine, single vs repeated doses and the child's age, still need to be clarified for use in clinical practice.
Context. The reason for the observed thinness of the solar tachocline is still not well understood. One of the explanations that have been proposed is that a primordial magnetic field renders the ...rotation uniform in the radiation zone. Aims. We test here the validity of this magnetic scenario through 3D numerical MHD simulations that encompass both the radiation zone and the convection zone. Methods. The numerical simulations are performed with the anelastic spherical harmonics (ASH) code. The computational domain extends from 0.07R⊙ to 0.97R⊙. Results. In the parameter regime we explored, a dipolar fossil field aligned with the rotation axis cannot remain confined in the radiation zone. When the field lines are allowed to interact with turbulent unstationary convective motions at the base of the convection zone, 3D effects prevent the field confinement. Conclusions. In agreement with previous work, we find that a dipolar fossil field, even when it is initially buried deep inside the radiation zone, will spread into the convective zone. According to Ferraro’s law of iso-rotation, it then imprints on the radiation zone the latitudinal differential rotation of the convection zone, which is not observed.
Aims. We investigate the magnetic field at the surface of 48 red giants selected as promising for detection of Stokes V Zeeman signatures in their spectral lines. In our sample, 24 stars are ...identified from the literature as presenting moderate to strong signs of magnetic activity. An additional 7 stars are identified as those in which thermohaline mixing appears not to have occured, which could be due to hosting a strong magnetic field. Finally, we observed 17 additional very bright stars which enable a sensitive search to be performed with the spectropolarimetric technique. Methods. We use the spectropolarimeters Narval and ESPaDOnS to detect circular polarization within the photospheric absorption lines of our targets. We treat the spectropolarimetric data using the least-squares deconvolution method to create high signal-to-noise ratio mean Stokes V profiles. We also measure the classical S-index activity indicator for the Ca ii H&K lines, and the stellar radial velocity. To infer the evolutionary status of our giants and to interpret our results, we use state-of-the-art stellar evolutionary models with predictions of convective turnover times. Results. We unambiguously detect magnetic fields via Zeeman signatures in 29 of the 48 red giants in our sample. Zeeman signatures are found in all but one of the 24 red giants exhibiting signs of activity, as well as 6 out of 17 bright giant stars. However no detections were obtained in the 7 thermohaline deviant giants. The majority of the magnetically detected giants are either in the first dredge up phase or at the beginning of core He burning, i.e. phases when the convective turnover time is at a maximum: this corresponds to a “magnetic strip” for red giants in the Hertzsprung-Russell diagram. A close study of the 16 giants with known rotational periods shows that the measured magnetic field strength is tightly correlated with the rotational properties, namely to the rotational period and to the Rossby number Ro. Our results show that the magnetic fields of these giants are produced by a dynamo, possibly of α-ω origin since Ro is in general smaller than unity. Four stars for which the magnetic field is measured to be outstandingly strong with respect to that expected from the rotational period/magnetic field relation or their evolutionary status are interpreted as being probable descendants of magnetic Ap stars. In addition to the weak-field giant Pollux, 4 bright giants (Aldebaran, Alphard, Arcturus, η Psc) are detected with magnetic field strength at the sub-Gauss level. Besides Arcturus, these stars were not considered to be active giants before this study and are very similar in other respects to ordinary giants, with S-index indicating consistency with basal chromospheric flux.
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