Ultrasound-guided percutaneous tracheal puncture: a computer-tomographic controlled study in cadavers

Ultrasound-guided techniques are increasingly used in anaesthetic practice to identify tissues beneath the skin and to increase the accuracy of placement of needles close to targeted structures. To examine ultrasound's usefulness for dilatational tracheostomy, we performed ultrasound-guided tracheal punctures in human cadavers followed by computer-tomographic (CT) control.

Different Learning Curves for Axillary Brachial Plexus Block: Ultrasound Guidance versus Nerve Stimulation

Little is known about the learning of the skills needed to perform ultrasound- or nerve stimulator-guided peripheral nerve blocks. The aim of this study was to compare the learning curves of residents trained in ultrasound guidance versus residents trained in nerve stimulation for axillary brachial plexus block. Ten residents with no previous experience with using ultrasound received ultrasound training and another ten residents with no previous experience with using nerve stimulation received nerve stimulation training. The novices' learning curves were generated by retrospective data analysis out of our electronic anaesthesia database. Individual success rates were pooled, and the institutional learning curve was calculated using a bootstrapping technique in combination with a Monte Carlo simulation procedure. The skills required to perform successful ultrasound-guided axillary brachial plexus block can be learnt faster and lead to a higher final success rate compared to nerve stimulator-guided axillary brachial plexus block.

Thin-Film Sparse Boundary Array Design for Passive Acoustic Mapping During Ultrasound Therapy

A new 2-D hydrophone array for ultrasound therapy monitoring is presented, along with a novel algorithm for passive acoustic mapping using a sparse weighted aperture. The array is constructed using existing polyvinylidene fluoride (PVDF) ultrasound sensor technology, and is utilized for its broadband characteristics and its high receive sensitivity. For most 2-D arrays, high-resolution imagery is desired, which requires a large aperture at the cost of a large number of elements. The proposed array's geometry is sparse, with elements only on the boundary of the rectangular aperture. The missing information from the interior is filled in using linear imaging techniques. After receiving acoustic emissions during ultrasound therapy, this algorithm applies an apodization to the sparse aperture to limit side lobes and then reconstructs acoustic activity with high spatiotemporal resolution. Experiments show verification of the theoretical point spread function, and cavitation maps in agar phantoms correspond closely to predicted areas, showing the validity of the array and methodology.

Effects of cardiac preload reduction and dobutamine on hepatosplanchnic blood flow regulation in porcine endotoxemia

Insufficient cardiac preload and impaired contractility are frequent in early sepsis. We explored the effects of acute cardiac preload reduction and dobutamine on hepatic arterial (Qha) and portal venous (Qpv) blood flows during endotoxin infusion. We hypothesized that the hepatic arterial buffer response (HABR) is absent during preload reduction and reduced by dobutamine. In anesthetized pigs, endotoxin or vehicle (n = 12, each) was randomly infused for 18 h. HABR was tested sequentially by constricting superior mesenteric artery (SMA) or inferior vena cava (IVC). Afterward, dobutamine at 2.5, 5.0, and 10.0 μg/kg per minute or another vehicle (n = 6, each) was randomly administered in endotoxemic and control animals, and SMA was constricted during each dose. Systemic (cardiac output, thermodilution) and carotid, splanchnic, and renal blood flows (ultrasound Doppler) and blood pressures were measured before and during administration of each dobutamine dose. HABR was expressed as hepatic arterial pressure/flow ratio. Compared with controls, 18 h of endotoxin infusion was associated with decreased mean arterial blood pressure [49 ± 11 mmHg vs. 58 ± 8 mmHg (mean ± SD); P = 0.034], decreased renal blood flow, metabolic acidosis, and impaired HABR during SMA constriction [0.32 (0.18-1.32) mmHg/ml vs. 0.22 (0.08-0.60) mmHg/ml; P = 0.043]. IVC constriction resulted in decreased Qpv in both groups; whereas Qha remained unchanged in controls, it decreased after 18 h of endotoxemia (P = 0.031; constriction-time-group interaction). One control and four endotoxemic animals died during the subsequent 6 h. The maximal increase of cardiac output during dobutamine infusion was 47% (22-134%) in controls vs. 53% (37-85%) in endotoxemic animals. The maximal Qpv increase was significant only in controls [24% (12-47%) of baseline (P = 0.043) vs. 17% (-7-32%) in endotoxemia (P = 0.109)]. Dobutamine influenced neither Qha nor HABR. Our data suggest that acute cardiac preload reduction is associated with preferential hepatic arterial perfusion initially but not after established endotoxemia. Dobutamine had no effect on the HABR.

Rapid Facilitation of Ultrasound Production and Lordosis in Female Hamsters by Horizontal Cuts Between the Septum and Preoptic Area

Horizontal cuts between the septum and preoptic area (anterior roof deafferentation, or ARD) dramatically affect sexual behavior, and in ways that could explain a variety of differences across behavioral categories (precopulatory, copulatory), species, and the sexes. Yet little is known about how these effects develop. Such information would be useful generally and could be pivotal in clarifying the mechanism for ultrasonic vocalization in female hamsters. Ultrasounds serve these animals as precopulatory signals that can attract males and help initiate mating. Their rates can be increased by either ARD or lesions of the ventromedial hypothalamus (VMN). If these effects are independent, they would require a mechanism that includes multiple structures and pathways within the forebrain and hypothalamus. However, it currently is not clear if they are independent: VMN lesions could affect vocalization by causing incidental damage to the same fibers targeted by ARD. Fortunately, past studies of VMN lesions have described a response with a very distinctive time course. This raises the possibility of assessing the independence of the two lesion effects by describing just the development of the response to ARD. To accomplish this, female hamsters were observed for levels of ultrasound production and lordosis before and after control surgery or ARD. As expected, both behaviors were facilitated by these cuts. Further, these effects began to appear by two days after surgery and were fully developed by six days. These results extend previous descriptions of the ARD effect by describing its development and time course. In turn, the rapid responses to ARD suggest that these cuts trigger disinhibitory changes in pathways that differ from those affected by VMN lesions. 2013

Serial in vivo intravascular ultrasound-based echogenicity changes of everolimus-eluting bioresorbable vascular scaffold during the first 12 months after implantation insights from the ABSORB B trial

This study sought to investigate quantitative and homogeneity differential echogenicity changes of the ABSORB scaffold (1.1) during the first year after implantation.

Associations of Reactive Hyperemia Index and Intravascular Ultrasound-Assessed Coronary Plaque Morphology in Patients With Coronary Artery Disease

Although reactive hyperemia index (RHI) predicts future coronary events, associations with intravascular ultrasound (IVUS)-assessed coronary plaque structure have not been reported. This study therefore investigated associations between RHI and IVUS-assessed coronary plaques. In 362 patients RHI was measured by noninvasive peripheral arterial tonometry and coronary plaque components (fibrous, fibrofatty, necrotic core, and dense calcium) were identified by IVUS in 594 vessel segments of the left anterior descending, circumflex, and/or right coronary arteries. RHI values <1.67 were considered abnormal. Analysis of variance was used to detect independent associations between RHI and plaque composition. Patients with an abnormal RHI had greater plaque burden (41% vs 39% in patients with normal RHI, p = 0.047). Compared to patients with normal RHI, plaque of patients with abnormal RHI had more necrotic core (21% vs 17%, p <0.001) and dense calcium (19% vs 15%, p <0.001) and less fibrous (49% vs 54%, p <0.001) and fibrofatty (11% vs 14%, p = 0.002) tissue. After adjustment for age, gender, cardiovascular risk factors, and drug therapy, abnormal RHI remained significantly associated with fibrous (F ratio 14.79, p <0.001), fibrofatty (F ratio 5.66, p = 0.018), necrotic core (F ratio 14.47, p <0.001), and dense calcium (F ratio 10.80, p = 0.001) volumes. In conclusion, coronary artery plaques of patients with abnormal RHI had a larger proportion of necrotic core and dense calcium. The association of an abnormal RHI with a plaque structure that is more prone to rupture may explain why these patients exhibit a greater risk of coronary events.

Determination of hemispheric dominance with mental rotation using functional transcranial Doppler sonography and FMRI

the aim of this study was to investigate specific activation patterns and potential gender differences during mental rotation and to investigate whether functional magnetic resonance imaging (fMRI) and functional transcranial Doppler sonography (fTCD) lateralize hemispheric dominance concordantly.

Assessment of melanocytic skin lesions with a high-definition laser Doppler imaging system

Early detection is a major goal in the management of malignant melanoma. Besides clinical assessment many noninvasive technologies such as dermoscopy, digital dermoscopy and in vivo laser scanner microscopy are used as additional methods. Herein we tested a system to assess lesional perfusion as a tool for early melanoma detection.

Interobserver variability in assessment of cranial ultrasound in very preterm infants

Cranial ultrasound (cUS) findings help doctors in the clinical management of preterm infants and in their discussion with parents regarding prediction of outcome. cUS is often used as outcome measure in clinical research studies. Accurate cUS performance and interpretation is therefore required.