Interaction of magnesium sulphate with vecuronium-induced neuromuscular blockt

We have investigated the interaction between magnesium sulphate 40 mg kg−1 i.v. and vecuronium. First, we determined the effect of pretreatment with magnesium on the potency of vecuronium using a single bolus dose-response technique. In addition, we compared the time course of vecuronium-induced neuromuscular block (vecuronium 100 μg kg−1) with and without magnesium pretreatment. For both parts, neuromuscular block was assessed by electromyography. In addition, the effect of magnesium pretreatment on vecuronium-induced neuromuscular block was investigated in the context of rapid sequence induction of anaesthesia. We found that the neuromuscular potency of vecuronium was increased by pretreatment with magnesium sul phate. The ED50 and ED90 of vecuronium with MgSO4 were 25% lower than without MgSO4 (ED50 21.3 vs 26.9 μg kg−1 ED90 34.2 vs 45.7 μg kg−1 P < 0.05 for both). Mean onset time was 147.3 (SD 22.2) s in the MgSO4 group vs 297.3 (122) s for controls (P < 0.05). Clinical duration was prolonged (MgSO4-vecuronium 43.3 (9) min vs 25.2 (5.1) min for controls; P < 0.05). This was also true for the recovery index (20.1 (6.6) mm vs 10.6 (3.4) min; P < 0.05) and duration to 75% recovery (63.4 (9.9) min vs 35.8 (6.9) min; < 0.05). In the context of rapid sequence induction, pretreatment with MgSO4 improved the intubating score of vecuronium compared with vecuronium without MgSO4 reach ing the same quality as that with suxamethonium 1 mg kg−1. We conclude that magnesium pretreat ment increased the neuromuscular potency of vecuronium, in addition to modifying the time course of its neuromuscular bloc

Concentration of rocuronium in cerebrospinal fluid of patients undergoing cerebral aneurysm clipping†

Background. This study assessed the concentration of rocuronium in the cerebrospinal fluid (CSF) of patients undergoing cerebral aneurysm clipping, and investigated whether the mode of administration (single bolus vs continuous infusion) influenced the CSF concentration. Methods. Twenty patients with subarachnoid haemorrhage were randomly allocated to receive a bolus dose (bolus group), or a bolus followed by a continuous infusion of rocuronium (infusion group) (n=10 for each group). Arterial blood and ventricular CSF were sampled 2 h after the rocuronium bolus. Samples were analysed by liquid chromatography electrospray ionization‐tandem mass spectrometry. Results. Rocuronium could be detected in all the CSF samples. The mean (range) CSF concentration was 2.2 (0.9-4.6) ng ml-1 in the bolus group and 12.4 (2.4-34.6) ng ml-1 in the infusion group; P<0.01. Conclusions. This study demonstrated that rocuronium, normally not considered to cross the blood-brain barrier, is regularly found in the CSF of patients undergoing cerebral clipping; continuous infusion of the drug led to higher plasma and CSF concentrations than after a single bolus dose. Br J Anaesth 2004; 92: 419-2

Dermal reaction and bigeminal premature ventricular contractions due to neostigmine: a case report

<p>Abstract</p> <p>Introduction</p> <p>Neostigmine is a frequently used acetylcholinesterase inhibitor administered to reverse muscular relaxation caused by nondepolarizing neuromuscular relaxants in patients recovering from general anesthesia. Severe allergic reactions and urticaria are rarely reported following the use of neostigmine bromide, and never with methylsulfate-containing drugs. In this case, bigeminal premature ventricular contractions added to urticaria provides a warning about the possibility of a life-threatening situation.</p> <p>Case presentation</p> <p>We report the case of a 23-year-old Persian woman who presented with bigeminal premature ventricular contractions along with urticarial lesions on her arm and trunk as soon as she was administered neostigmine methylsulfate after undergoing a laparoscopy for ectopic pregnancy.</p> <p>Conclusion</p> <p>This case report could be of value not only for anesthesiologists who routinely use neostigmine but also for others who administer the pharmaceutical preparation in other situations. The report presents a rare case of drug reaction following neostigmine use. As a result, one should consider any drug a probable cause of drug reaction. The preparation of resuscitative facilities, therefore, is necessary prior to the prescription of the medication.</p

The role of carbon in red giant spectro-seismology

Although red clump stars function as reliable standard candles, their surface characteristics (i.e. $T_\text{eff}$, $\log g$, and [Fe/H]) overlap with those of red giant branch stars, which are not standard candles. Recent results have revealed that spectral features containing carbon (e.g. CN molecular bands) carry information correlating with the "gold-standard" asteroseismic classifiers that distinguish red clump from red giant branch stars. However, the underlying astrophysical processes driving the correlation between these spectroscopic and asteroseismic quantities in red giants remain inadequately explored. This study aims to enhance our understanding of this "spectro-seismic" effect, by refining the list of key spectral features predicting red giant evolutionary state. In addition, we conduct further investigation into those key spectral features to probe the astrophysical processes driving this connection. We employ the data-driven The Cannon algorithm to analyse high-resolution ($R\sim80,000$) Veloce Rosso spectra from the Anglo-Australian Telescope for 301 red giant stars (where asteroseismic classifications from the TESS mission are known for 123 of the stars). The results highlight molecular spectroscopic features, particularly those containing carbon (e.g. CN), as the primary indicators of the evolutionary states of red giant stars. Furthermore, by investigating CN isotopic pairs (that is, $^{12}$C$^{14}$N and $^{13}$C$^{14}$N) we find suggestions of statistically significant differences in the reduced equivalent widths of such lines, suggesting that physical processes that change the surface abundances and isotopic ratios in red giant stars, such as deep mixing, are the driving forces of the "spectro-seismic" connection of red giants.Comment: 13 pages, 9 figures, accepted to MNRA

YETI observations of the young transiting planet candidate CVSO 30 b

CVSO 30 is a unique young low-mass system, because, for the first time, a close-in transiting and a wide directly imaged planet candidates are found around a common host star. The inner companion, CVSO 30 b, is the first possible young transiting planet orbiting a previously known weak-lined T-Tauri star. With five telescopes of the 'Young Exoplanet Transit Initiative' (YETI) located in Asia, Europe and South America we monitored CVSO 30 over three years in a total of 144 nights and detected 33 fading events. In two more seasons we carried out follow-up observations with three telescopes. We can confirm that there is a change in the shape of the fading event between different observations and that the fading event even disappears and reappears. A total of 38 fading event light curves were simultaneously modelled. We derived the planetary, stellar, and geometrical properties of the system and found them slightly smaller but in agreement with the values from the discovery paper. The period of the fading event was found to be 1.36 s shorter and 100 times more precise than the previous published value. If CVSO 30 b would be a giant planet on a precessing orbit, which we cannot confirm, yet, the precession period may be shorter than previously thought. But if confirmed as a planet it would be the youngest transiting planet ever detected and will provide important constraints on planet formation and migration time-scales.Comment: 14 pages (20 with appendix), 7 figures (16 with appendix), 6 tables (7 with appendix

Many Roads Lead to Lithium: Formation Pathways For Lithium-Rich Red Giants

Stellar models predict that lithium (Li) inside a star is destroyed during the first dredge-up phase, yet 1.2% of red giant stars are Li-rich. We aim to uncover possible origins of this population, by analysing 1155 Li-rich giants (A(Li) $\geq$ 1.5) in GALAH DR3. To expose peculiar traits of Li-rich stars, we construct a reference sample of Li-normal (doppelg\"anger) stars with matched evolutionary state and fiducial supernova abundances. Comparing Li-rich and doppelg\"anger spectra reveals systematic differences in the H-$\alpha$ and Ca-triplet line profiles associated with the velocity broadening measurement. We also find twice as many Li-rich stars appear to be fast rotators (2% with $v_\textrm{broad} \gtrsim 20$ km s$^{-1}$) compared to doppelg\"angers. On average, Li-rich stars have higher abundances than their doppelg\"angers, for a subset of elements, and Li-rich stars at the base of RGB have higher mean $s-$process abundances ($\geq 0.05$ dex for Ba, Y, Zr), relative to their doppelg\"angers. External mass-transfer from intermediate-mass AGB companions could explain this signature. Additional companion analysis excludes binaries with mass ratios $\gtrsim$ 0.5 at $\gtrsim$ 7 AU. We also discover that highly Ba-enriched stars are missing from the Li-rich population, possibly due to low-mass AGB companions which preclude Li-enrichment. Finally, we confirm a prevalence of Li-rich stars on the red clump that increases with lithium, which supports an evolutionary state mechanism for Li-enhancement. Multiple culprits, including binary spin-up and mass-transfer, are therefore likely mechanisms of Li-enrichment.Comment: 29 pages, 19 figures, 6 tables. Submitted to Ap

Gaia FGK Benchmark stars: Opening the black box of stellar element abundance determination

Gaia and its complementary spectroscopic surveys combined will yield the most comprehensive database of kinematic and chemical information of stars in the Milky Way. The Gaia FGK benchmark stars play a central role in this matter as they are calibration pillars for the atmospheric parameters and chemical abundances for various surveys. The spectroscopic analyses of the benchmark stars are done by combining different methods, and the results will be affected by the systematic uncertainties inherent in each method. In this paper, we explore some of these systematic uncertainties. We determined line abundances of Ca, Cr, Mn and Co for four benchmark stars using six different methods. We changed the default input parameters of the different codes in a systematic way and found, in some cases, significant differences between the results. Since there is no consensus on the correct values for many of these default parameters, we urge the community to raise discussions towards standard input parameters that could alleviate the difference in abundances obtained by different methods. In this work, we provide quantitative estimates of uncertainties in elemental abundances due to the effect of differing technical assumptions in spectrum modelling

Direct Imaging discovery of a second planet candidate around the possibly transiting planet host CVSO 30

We surveyed the 25 Ori association for direct-imaging companions. This association has an age of only few million years. Among other targets, we observed CVSO 30, which has recently been identified as the first T Tauri star found to host a transiting planet candidate. We report on photometric and spectroscopic high-contrast observations with the Very Large Telescope, the Keck telescopes, and the Calar Alto observatory. They reveal a directly imaged planet candidate close to the young M3 star CVSO 30. The JHK-band photometry of the newly identified candidate is at better than 1 sigma consistent with late-type giants, early-T and early-M dwarfs, and free-floating planets. Other hypotheses such as galaxies can be excluded at more than 3.5 sigma. A lucky imaging z' photometric detection limit z'= 20.5 mag excludes early-M dwarfs and results in less than 10 MJup for CVSO 30 c if bound. We present spectroscopic observations of the wide companion that imply that the only remaining explanation for the object is that it is the first very young (Publisher PDFPeer reviewe