4 research outputs found
Multi-tracer analysis of straight depolarisation canals in the surroundings of the 3C 196 field
Context. Faraday tomography of a field centred on the extragalactic point source 3C 196 with the LOw Frequency ARray (LOFAR) revealed an intertwined structure of diffuse polarised emission with straight depolarisation canals and tracers of the magnetised and multi-phase interstellar medium (ISM), such as dust and line emission from atomic hydrogen (HI).
Aims. This study aims at extending the multi-tracer analysis of LOFAR data to three additional fields in the surroundings of the 3C 196 field. For the first time, we study the three-dimensional structure of the LOFAR emission by determining the distance to the depolarisation canals.
Methods. We used the rolling Hough transform to compare the orientation of the depolarisation canals with that of the filamentary structure seen in HI, and based on starlight and dust polarisation data, with that of the plane-of-the-sky magnetic field. Stellar parallaxes from Gaia complemented the starlight polarisation with the corresponding distances.
Results. Faraday tomography of the three fields shows a rich network of diffuse polarised emission at Faraday depths between − 10 and + 15 rad m−2. A complex system of straight depolarisation canals resembles that of the 3C 196 field. The depolarisation canals align both with the HI filaments and with the magnetic field probed by dust. The observed alignment suggests that an ordered magnetic field organises the multiphase ISM over a large area (~20°). In one field, two groups of stars at distances below and above 200 pc, respectively, show distinct magnetic field orientations. These are both comparable with the orientations of the depolarisation canals in the same field. We conclude that the depolarisation canals likely trace the same change in the magnetic field as probed by the stars, which corresponds to the edge of the Local Bubble
intravenous lidocaine attenuates distention of the optical nerve sheath, a correlate of intracranial pressure, during endotracheal intubation
Background:By preventing hypoxia and hypercapnia, advanced airway management can save lives among patients with traumatic brain injury. During endotracheal intubation (eti), tracheal stimulation causes an increase in intracranial pressure (icP), which may impair brain perfusion. it has been suggested that intravenous lidocaine might attenuate this icP response. We hypothesized that adding lidocaine to the standard induction medication for general anesthesia might reduce the icP response to eti. Here, we measured the optical nerve sheath diameter (oNsD) as a correlate of icP and evaluated the effect of intravenous lidocaine on oNsD during and after eti in patients undergoing anesthesia. Methods:this double-blinded, randomized placebo-controlled trial included 60 patients with american society of anesthesiologists i or ii physical status that were scheduled for elective surgery under general anesthesia. in addition to the standard anesthesia medication, 30 subjects received 1.5 mg/kg 1% lidocaine (0.15 ml/kg, oNsDlidocaine) and 30 received 0.15 ml/kg 0.9% Nacl (oNsDplacebo). oNsDs were measured with ultrasound on the left eye, before (t0), during (t1), and 4 times after eti (t2-5 at 5-min intervals). Results:Compared to placebo, lidocaine did not significantly affect the baseline ONSD after anesthesia induction measured at t0. During eti, the oNsDlidocaine was significantly smaller (β=−0.24 mm P=0.022) than the ONSDplacebo. at t4 and t5, the oNsDplacebo increased steadily, up to 20 min after eti, but the oNsDlidocaine tended to return to baseline levels. Conclusions: We found that the oNsD was distended during and after eti in anesthetized patients, and intravenous lidocaine attenuated this effect.</p
intravenous lidocaine attenuates distention of the optical nerve sheath, a correlate of intracranial pressure, during endotracheal intubation
Background:By preventing hypoxia and hypercapnia, advanced airway management can save lives among patients with traumatic brain injury. During endotracheal intubation (eti), tracheal stimulation causes an increase in intracranial pressure (icP), which may impair brain perfusion. it has been suggested that intravenous lidocaine might attenuate this icP response. We hypothesized that adding lidocaine to the standard induction medication for general anesthesia might reduce the icP response to eti. Here, we measured the optical nerve sheath diameter (oNsD) as a correlate of icP and evaluated the effect of intravenous lidocaine on oNsD during and after eti in patients undergoing anesthesia. Methods:this double-blinded, randomized placebo-controlled trial included 60 patients with american society of anesthesiologists i or ii physical status that were scheduled for elective surgery under general anesthesia. in addition to the standard anesthesia medication, 30 subjects received 1.5 mg/kg 1% lidocaine (0.15 ml/kg, oNsDlidocaine) and 30 received 0.15 ml/kg 0.9% Nacl (oNsDplacebo). oNsDs were measured with ultrasound on the left eye, before (t0), during (t1), and 4 times after eti (t2-5 at 5-min intervals). Results:Compared to placebo, lidocaine did not significantly affect the baseline ONSD after anesthesia induction measured at t0. During eti, the oNsDlidocaine was significantly smaller (β=−0.24 mm P=0.022) than the ONSDplacebo. at t4 and t5, the oNsDplacebo increased steadily, up to 20 min after eti, but the oNsDlidocaine tended to return to baseline levels. Conclusions: We found that the oNsD was distended during and after eti in anesthetized patients, and intravenous lidocaine attenuated this effect.</p
Detection of Ischemic ST-Segment Changes Using a Novel Handheld ECG Device in a Porcine Model
Background: Portable, smartphone-sized electrocardiography (ECG) has the potential to reduce time to treatment for patients suffering acute cardiac ischemia, thereby lowering the morbidity and mortality. In the UMC Utrecht, a portable, smartphone-sized, multi-lead precordial ECG recording device (miniECG 1.0, UMC Utrecht) was developed. Objectives: The purpose of this study was to investigate the ability of the miniECG to capture ischemic ECG changes in a porcine coronary occlusion model. Methods: In 8 animals, antero-septal myocardial infarction was induced by 75-minute occlusion of the left anterior descending artery, after the first or second diagonal. MiniECG and 12-lead ECG recordings were acquired simultaneously before, during and after coronary artery occlusion and ST-segment deviation was evaluated. Results: During the complete occlusion and reperfusion period, miniECG showed large ST-segment deviation in comparison to 12-lead ECG. MiniECG ST-segment deviation was observed within 1 minute for most animals. The miniECG was positive for ischemia (ie, ST-segment deviation ≥1 mm) for 99.7% (Q1-Q3: 99.6%-99.9%) of the occlusion time, while the 12-lead was only positive for 79.8% (Q1-Q3: 81.1%-98.7%) of the time (P = 0.018). ST-segment deviation reached maxima of 10.5 mm [95% CI: 6.5-14.5 mm] vs 5.0 mm [95% CI: 2.0-8.0 mm] for the miniECG vs 12-lead ECG, respectively. Conclusions: MiniECG ST-segment deviation was observed early and was of large magnitude during 75 minutes of porcine transmural antero-septal infarction. The miniECG was positive for ischemia for the complete occlusion period. These findings demonstrate the potential of the miniECG in the detection of cardiac ischemia. Although clinical research is required, data suggests that the miniECG is a promising tool for the detection of cardiac ischemia.</p