Limits on the Existence of sub-MeV Sterile Neutrinos from the Decay of

Sterile neutrinos are natural extensions to the standard model of particle physics and provide a possible portal to the dark sector. We report a new search for the existence of sub-MeV sterile neutrinos using the decay-momentum reconstruction technique in the decay of ^{7}Be. The experiment measures the total energy of the ^{7}Li daughter atom from the electron capture decay of ^{7}Be implanted into sensitive superconducting tunnel junction (STJ) quantum sensors. This first experiment presents data from a single STJ operated at a low count rate for a net total of 28 days, and provides exclusion limits on sterile neutrinos in the mass range from 100 to 850 keV that improve upon previous work by up to an order of magnitude.

Association of obesity with failure of ultrasound-guided axillary brachial plexus block: a two-centre, prospective, observational, cohort study.

The objective of this study was to evaluate whether the failure rate of ultrasound-guided axillary brachial plexus block is similar in obese patients compared with non-obese patients when performed as the primary anaesthetic technique. We recruited 105 obese (body mass index ≥ 30 kg.m-2 ) and 144 non-obese patients to this prospective, observational, cohort study conducted at two Canadian centres. A perineural technique of axillary brachial plexus block was performed using 30 ml ropivacaine 0.5% under real-time ultrasound guidance. Sensory and motor block assessment was carried out every 5 min until 30 min after block completion in all four terminal nerve distributions (radial, median, ulnar and musculocutaneous nerve). A composite score consisting of three sensory points and three motor points was used for assessment in each nerve distribution. A failed block was defined as a score of less than 14 points out of a possible 16 points, or a sensory block score less than 7 out of 8 points 30 min after block completion. Thirty minutes after block completion, obese patients had a higher failure rate of 33.7% (34/101) compared with 17.8% (24/135) for non-obese patients, with a failure rate difference (95%CI) of 15.9% (6.4-27.1%) between the groups. The median (IQR [range]) time to achieve a successful block in obese patients was 25 (20-30 [5-30]) min, compared with non-obese patients at 20 (15-30 [5-30]) min (p = 0.003). Despite a higher sensory-motor failure rate as per the composite score, the axillary brachial plexus block provided adequate surgical anaesthesia as indicated by a low need for conversion to general anaesthetic in obese (8.6%) and non-obese patients (7.0%; p = 0.656). This study showed that despite ultrasound guidance, obese patients had a slower onset time and higher axillary brachial plexus block failure rate at 30 min compared with non-obese patients.

The McGrath® Series 5 videolaryngoscope vs the Macintosh laryngoscope: a randomised, controlled trial in patients with a simulated difficult airway.

We compared the McGrath® Series 5 videolaryngoscope with the Macintosh laryngoscope in a simulated difficult airway, using manual in-line stabilisation in 88 anaesthestised patients of ASA physical status 1-2. The primary outcome was laryngoscopic view. Secondary outcomes included rates of successful tracheal intubation and complications. A Cormack and Lehane grade-1 or -2 view was found in all patients when using the McGrath compared with 45 (51%, p < 0.0001) using the Macintosh laryngoscopes. The mean (SD) percentage of glottic opening was 82 (23)% using the McGrath compared with 13 (23)% using the Macintosh (p < 0.0001). In 66 out of 88 patients (75%), the McGrath improved the glottic view by one to three grades compared with the Macintosh (p < 0.001). Intubation of the trachea was successful in all patients using the McGrath, while the Macintosh was successful in 26 (59%, p < 0.001). There was no significant difference in the complication rates between the devices.

Maternal respiratory distress and successful reversal with sugammadex during intrauterine transfusion with fetal paralysis.

A 70 kg, 34-year-old woman at 29 weeks-of-gestation required intrauterine transfusion for Rh (D) alloimmunization. In the ambulatory treatment clinic, 19 mg of rocuronium was administered intramuscularly in split doses into the fetal buttock. The fetus moved and inadvertent maternal neuromuscular blockade occurred, leading to respiratory distress. The patient was transferred to the operating room where she had poor muscle tone, dyspnea and dysphonia. Sugammadex 100 mg was administered intravenously and complete resolution of neuromuscular blockade was demonstrated using a Neuromuscular Transmission™ monitor. When neuromuscular blocking agents are administered in ambulatory settings, management protocols, reversal agents, and skilled assistance should be immediately available for managing potentially life-threatening complications.

An observational assessment of the sublingual microcirculation of pregnant and non-pregnant women.

BACKGROUND: The microcirculation is responsible for distribution of blood within tissues, delivery of oxygen and other nutrients, and regulation of blood pressure. The objective of this study was to compare the sublingual microcirculation of pregnant participants to that of comparable non-pregnant volunteers. METHODS: Two groups of participants were recruited: a group of pregnant, non-laboring women with singleton pregnancies at term gestation and a control group of age-comparable non-pregnant volunteers. A sidestream dark field imaging device was applied to the sublingual mucosal surface obtaining a steady image for at least 20 s duration, in five visual fields. The resultant five video clips per participant were analyzed blindly and at random to prevent coupling between images. The mean microvascular flow index values for each group were compared using a paired t-test. RESULTS: Thirty-seven participants were recruited (19 pregnant, 18 non-pregnant); a single pregnant participant was withdrawn because of technical issues. Baseline characteristics were similar with the exception of weight and body mass index. The mean microvascular flow index was significantly higher in the pregnant group 2.7 ± 0.2 compared to the non-pregnant group 2.5 ± 0.3 (P = 0.021), while the perfused vessel density and proportion of perfused vessels were not significantly different (P = 0.707 and 0.403, respectively). CONCLUSION: The microvascular flow index of pregnant women is higher than a comparable non-pregnant group, which appears to correlate with the physiological changes of pregnancy.