Technical assessment of resolution of handheld ultrasound devices and clinical implications.

PURPOSE: Since handheld ultrasound devices are becoming increasingly ubiquitous, objective criteria to determine image quality are needed. We therefore conducted a comparison of objective quality measures and clinical performance. MATERIAL AND METHODS: A comparison of handheld devices (Butterfly IQ+, Clarius HD, Clarius HD3, Philips Lumify, GE VScan Air) and workstations (GE Logiq E10, Toshiba Aplio 500) was performed using a phantom. As a comparison, clinical investigations were performed by two experienced ultrasonographers by measuring the resolution of anatomical structures in the liver, pancreas, and intestine in ten subjects. RESULTS: Axial full width at half maximum resolution (FWHM) of 100µm phantom pins at depths between one and twelve cm ranged from 0.6-1.9mm without correlation to pin depth. Lateral FWHM resolution ranged from 1.3-8.7mm and was positively correlated with depth (r=0.6). Axial and lateral resolution differed between devices (p<0.001) with the lowest median lateral resolution observed in the E10 (5.4mm) and the lowest axial resolution (1.6mm) for the IQ+ device. Although devices showed no significant differences in most clinical applications, ultrasonographers were able to differentiate a median of two additional layers in the wall of the sigmoid colon and one additional structure in segmental portal fields (p<0.05) using cartwheel devices. CONCLUSION: While handheld devices showed superior or similar performance in the phantom and routine measurements, workstations still provided superior clinical imaging and resolution of anatomical substructures, indicating a lack of objective measurements to evaluate clinical ultrasound devices.

Measurement Efficiency of a Teacher Rating Scale to Screen for Students at Risk for Social, Emotional, and Behavioral Problems.

Teacher rating scales are broadly used for psycho-educational assessment in schools. In particular, they play an important role in screening students for social, emotional, and behavioral problems. In order to optimize the efficiency of these measures, it is important to minimize the number of items comprising them while maintaining sound psychometric characteristics. This study examines the measurement efficiency of a teacher rating scale for student social, emotional, and behavioral risk. The goal was to shorten an existing behavior screening tool. A total of 139 classroom teachers and 2566 students from Grades 1-6 (Mage = 8.96 years, SD = 1.61) participated in the study. In sum, 35 items assessing internalizing and externalizing behavior problems were analyzed applying the item response theory (generalized partial credit model). The results show that social, emotional, and behavioral risks can be captured with a total of 12 items. This reduction of almost 66% of the initial item pool would take teachers about 90 s to fill out for one student. Thus, the rating scale can be used by teachers in an efficient yet psychometrically sound manner.

Variable ventilation versus stepwise lung recruitment manoeuvres for lung recruitment: A comparative study in an experimental model of atelectasis.

BACKGROUND: Variable ventilation recruits alveoli in atelectatic lungs, but it is unknown how it compares with conventional recruitment manoeuvres. OBJECTIVES: To test whether mechanical ventilation with variable tidal volumes and conventional recruitment manoeuvres have comparable effects on lung function. DESIGN: Randomised crossover study. SETTING: University hospital research facility. ANIMALS: Eleven juvenile mechanically ventilated pigs with atelectasis created by saline lung lavage. INTERVENTIONS: Lung recruitment was performed using two strategies, both with an individualised optimal positive-end expiratory pressure (PEEP) associated with the best respiratory system elastance during a decremental PEEP trial: conventional recruitment manoeuvres (stepwise increase of PEEP) in pressure-controlled mode) followed by 50 min of volume-controlled ventilation (VCV) with constant tidal volume, and variable ventilation, consisting of 50 min of VCV with random variation in tidal volume. MAIN OUTCOME MEASURES: Before and 50 min after each recruitment manoeuvre strategy, lung aeration was assessed by computed tomography, and relative lung perfusion and ventilation (0% = dorsal, 100% = ventral) were determined by electrical impedance tomography. RESULTS: After 50 min, variable ventilation and stepwise recruitment manoeuvres decreased the relative mass of poorly and nonaerated lung tissue (percent lung mass: 35.3 ±â€Š6.2 versus 34.2 ±â€Š6.6, P  = 0.303); reduced poorly aerated lung mass compared with baseline (-3.5 ±â€Š4.0%, P  = 0.016, and -5.2 ±â€Š2.8%, P  < 0.001, respectively), and reduced nonaerated lung mass compared with baseline (-7.2 ±â€Š2.5%, P  < 0.001; and -4.7 ±â€Š2.8%, P  < 0.001 respectively), while the distribution of relative perfusion was barely affected (variable ventilation: -0.8 ±â€Š1.1%, P  = 0.044; stepwise recruitment manoeuvres: -0.4 ±â€Š0.9%, P  = 0.167). Compared with baseline, variable ventilation and stepwise recruitment manoeuvres increased Pa O 2 (172 ±â€Š85mmHg, P  = 0.001; and 213 ±â€Š73 mmHg, P  < 0.001, respectively), reduced Pa CO 2 (-9.6 ±â€Š8.1 mmHg, P  = 0.003; and -6.7 ±â€Š4.6 mmHg, P  < 0.001, respectively), and decreased elastance (-11.4 ±â€Š6.3 cmH 2 O, P  < 0.001; and -14.1 ±â€Š3.3 cmH 2 O, P  < 0.001, respectively). Mean arterial pressure decreased during stepwise recruitment manoeuvres (-24 ±â€Š8 mmHg, P  = 0.006), but not variable ventilation. CONCLUSION: In this model of lung atelectasis, variable ventilation and stepwise recruitment manoeuvres effectively recruited lungs, but only variable ventilation did not adversely affect haemodynamics. TRIAL REGISTRATION: This study was registered and approved by Landesdirektion Dresden, Germany (DD24-5131/354/64).

Temperature profile and residual heat of monopolar laparoscopic and endoscopic dissection instruments.

BACKGROUND: Endoscopic and laparoscopic electrosurgical devices (ED) are of great importance in modern medicine but can cause adverse events such as tissue injuries and burns from residual heat. While laparoscopic tools are well investigated, detailed insights about the temperature profile of endoscopic knives are lacking. Our aim is to investigate the temperature and the residual heat of laparoscopic and endoscopic monopolar instruments to increase the safety in handling ED. METHODS: An infrared camera was used to measure the temperature of laparoscopic and endoscopic instruments during energy application and to determine the cooling time to below 50 °C at a porcine stomach. Different power levels and cutting intervals were studied to investigate their impact on the temperature profile. RESULTS: During activation, the laparoscopic hook exceeded 120 °C regularly for an up to 10 mm shaft length. With regards to endoknives, only the Dual Tip Knife showed a shaft temperature of above 50 °C. The residual heat of the laparoscopic hook remained above 50 °C for at least 15 s after activation. Endoknives cooled to below 50 °C in 4 s. A higher power level and longer cutting duration significantly increased the shaft temperature and prolonged the cooling time (p < 0.001). CONCLUSION: Residual heat and maximum temperature during energy application depend strongly on the chosen effect and cutting duration. To avoid potential injuries, the user should not touch any tissue with the laparoscopic hook for at least 15 s and with the endoknives for at least 4 s after energy application. As the shaft also heats up to over 120 °C, the user should be careful to avoid tissue contact during activation with the shaft. These results should be strongly considered for safety reasons when handling monopolar ED.

Continuous external negative pressure improves oxygenation and respiratory mechanics in Experimental Lung Injury in Pigs - A pilot proof-of-concept trial.

BACKGROUND: Continuous external negative pressure (CENP) during positive pressure ventilation can recruit dependent lung regions. We hypothesised that CENP applied regionally to the thorax or the abdomen only, increases the caudal end-expiratory transpulmonary pressure depending on positive end-expiratory pressure (PEEP) in lung-injured pigs. Eight pigs were anesthetised and mechanically ventilated in the supine position. Pressure sensors were placed in the left pleural space, and a lung injury was induced by saline lung lavages. A CENP shell was placed at the abdomen and thorax (randomised order), and animals were ventilated with PEEP 15, 7 and zero cmH2O (15 min each). On each PEEP level, CENP of - 40, - 30, - 20, - 10 and 0 cmH2O was applied (3 min each). Respiratory and haemodynamic variables were recorded. Electrical impedance tomography allowed assessment of centre of ventilation. RESULTS: Compared to positive pressure ventilation alone, the caudal transpulmonary pressure was significantly increased by CENP of ≤ 20 cmH2O at all PEEP levels. CENP of - 20 cmH2O reduced the mean airway pressure at zero PEEP (P = 0.025). The driving pressure decreased at CENP of ≤ 10 at PEEP of 0 and 7 cmH2O (P < 0.001 each) but increased at CENP of - 30 cmH2O during the highest PEEP (P = 0.001). CENP of - 30 cmH2O reduced the mechanical power during zero PEEP (P < 0.001). Both elastance (P < 0.001) and resistance (P < 0.001) were decreased at CENP ≤ 30 at PEEP of 0 and 7 cmH2O. Oxygenation increased at CENP of ≤ 20 at PEEP of 0 and 7 cmH2O (P < 0.001 each). Applying external negative pressure significantly shifted the centre of aeration towards dorsal lung regions irrespectively of the PEEP level. Cardiac output decreased significantly at CENP -20 cmH2O at all PEEP levels (P < 0.001). Effects on caudal transpulmonary pressure, elastance and cardiac output were more pronounced when CENP was applied to the abdomen compared with the thorax. CONCLUSIONS: In this lung injury model in pigs, CENP increased the end-expiratory caudal transpulmonary pressure. This lead to a shift of lung aeration towards dependent zones as well as improved respiratory mechanics and oxygenation, especially when CENP was applied to the abdomen as compared to the thorax. CENP values ≤ 20 cmH2O impaired the haemodynamics.

State- and trait-math anxiety and their relation to math performance in children: The role of core executive functions.

This study examines the interplay of state- and trait-math anxiety (MA) and core executive functions (CEF) on math achievement in children. According to attention control theory, MA affects the CEF by triggering the inhibition function, so that some working memory (WM) is blocked, thus reducing task processing capacity. However, research on the interplay between MA and CEF in children is rare, and the findings in the literature are inconsistent. In this paper, state- and trait-MA, math achievement, CEF (inhibition, cognitive flexibility, working memory capacity, global index of CEF) and self-ratings of ADHD symptoms (attention deficits, hyperactivity, impulsiveness) of 646 fourth and fifth grade students (48.1% girls) are assessed. CEF were evaluated with a tablet-based test. The data revealed negative correlations between state-MA and math achievement for all CEF levels and cognitive processes. However, inhibition control functioned as a moderator of the relation between state-MA and math achievement. Children with higher inhibition abilities showed more pronounced negative relations. No moderation effects were identified for working memory capacity and the CEF global index. The findings highlight the importance of distinguishing between these three CEF and raise questions for future research on the interplay between cognitive and affective factors as predictors of math achievement.

Relation of attention deficit hyperactivity disorder (ADHD) to basic number skills and arithmetic fact retrieval in children.

Although research has provided evidence for a clear association of core executive function (CEF) to math performance, fewer studies have been carried out on arithmetic fact retrieval in relation to the symptoms of attention deficit hyperactivity disorder (ADHD). The present study assessed mathematical achievement on a basic number skill test and on an arithmetic fact retrieval task. Besides math achievement, self-ratings of ADHD symptoms (attention deficits, hyperactivity, impulsivity), core executive functions (inhibition, cognitive flexibility, working memory capacity, global index) and state anxiety in 646 fourth and fifth grade students (48.1 % girls) were measured. CEF was evaluated by means of a tablet-based test. Regression analysis showed different predictors for both math abilities. While all CEF measures, inattention and impulsivity self-ratings predicted basic number skills, only inhibition, WMC and inattention self-rating were predictors of arithmetic fact retrieval. On the basis of a cluster analysis of ADHD self-ratings and CEF performance, three different groups were identified: 1: low ADHD, average CEF; 2: high ADHD, low CEF; 3: moderate ADHD, high CEF. Cluster 2 showed scores below the mean in both math scores, whereas cluster 3 exhibited performances above the mean in both math scores. No math differences were found between cluster 1 and 3. The data yield evidence that the association between CEF and math achievement depends on the specific math skill and test type. The results underline the importance of differentiating between CEF components and specific math abilities. Implications for future research on the associations between mathematics, ADHD and CEF are discussed.

Effects of variable versus nonvariable controlled mechanical ventilation on pulmonary inflammation in experimental acute respiratory distress syndrome in pigs.

BACKGROUND: Mechanical ventilation with variable tidal volumes (VT) may improve lung function and reduce ventilator-induced lung injury in experimental acute respiratory distress syndrome (ARDS). However, previous investigations were limited to less than 6 h, and control groups did not follow clinical standards. We hypothesised that 24 h of mechanical ventilation with variable VT reduces pulmonary inflammation (as reflected by neutrophil infiltration), compared with standard protective, nonvariable ventilation. METHODS: Experimental ARDS was induced in 14 anaesthetised pigs with saline lung lavage followed by injurious mechanical ventilation. Pigs (n=7 per group) were randomly assigned to using variable VT or nonvariable VT modes of mechanical ventilation for 24 h. In both groups, ventilator settings including positive end-expiratory pressure and oxygen inspiratory fraction were adjusted according to the ARDS Network protocol. Pulmonary inflammation (primary endpoint) and perfusion were assessed by positron emission tomography using 2-deoxy-2-[18F]fluoro-d-glucose and 68Gallium (68Ga)-labelled microspheres, respectively. Gas exchange, respiratory mechanics, and haemodynamics were quantified. Lung aeration was determined using CT. RESULTS: The specific global uptake rate of 18F-FDG increased to a similar extent regardless of mode of mechanical ventilation (median uptake for variable VT=0.016 min-1 [inter-quartile range, 0.012-0.029] compared with median uptake for nonvariable VT=0.037 min-1 [0.008-0.053]; P=0.406). Gas exchange, respiratory mechanics, haemodynamics, and lung aeration and perfusion were similar in both variable and nonvariable VT ventilatory modes. CONCLUSION: In a porcine model of ARDS, 24 h of mechanical ventilation with variable VT did not attenuate pulmonary inflammation compared with standard protective mechanical ventilation with nonvariable VT.

Effects of Positive End-Expiratory Pressure and Spontaneous Breathing Activity on Regional Lung Inflammation in Experimental Acute Respiratory Distress Syndrome.

OBJECTIVES: To determine the impact of positive end-expiratory pressure during mechanical ventilation with and without spontaneous breathing activity on regional lung inflammation in experimental nonsevere acute respiratory distress syndrome. DESIGN: Laboratory investigation. SETTING: University hospital research facility. SUBJECTS: Twenty-four pigs (28.1-58.2 kg). INTERVENTIONS: In anesthetized animals, intrapleural pressure sensors were placed thoracoscopically in ventral, dorsal, and caudal regions of the left hemithorax. Lung injury was induced with saline lung lavage followed by injurious ventilation in supine position. During airway pressure release ventilation with low tidal volumes, positive end-expiratory pressure was set 4 cm H2O above the level to reach a positive transpulmonary pressure in caudal regions at end-expiration (best-positive end-expiratory pressure). Animals were randomly assigned to one of four groups (n = 6/group; 12 hr): 1) no spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure - 4 cm H2O, 2) no spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure + 4 cm H2O, 3) spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure + 4 cm H2O, 4) spontaneous breathing activity and positive end-expiratory pressure = best-positive end-expiratory pressure - 4 cm H2O. MEASUREMENTS AND MAIN RESULTS: Global lung inflammation assessed by specific [F]fluorodeoxyglucose uptake rate (median [25-75% percentiles], min) was decreased with higher compared with lower positive end-expiratory pressure both without spontaneous breathing activity (0.029 [0.027-0.030] vs 0.044 [0.041-0.065]; p = 0.004) and with spontaneous breathing activity (0.032 [0.028-0.043] vs 0.057 [0.042-0.075]; p = 0.016). Spontaneous breathing activity did not increase global lung inflammation. Lung inflammation in dorsal regions correlated with transpulmonary driving pressure from spontaneous breathing at lower (r = 0.850; p = 0.032) but not higher positive end-expiratory pressure (r = 0.018; p = 0.972). Higher positive end-expiratory pressure resulted in a more homogeneous distribution of aeration and regional transpulmonary pressures at end-expiration along the ventral-dorsal gradient, as well as a shift of the perfusion center toward dependent zones in the presence of spontaneous breathing activity. CONCLUSIONS: In experimental mild-to-moderate acute respiratory distress syndrome, positive end-expiratory pressure levels that stabilize dependent lung regions reduce global lung inflammation during mechanical ventilation, independent from spontaneous breathing activity.

Magnetic Resonance Imaging for Quantitative Assessment of Lung Aeration: A Pilot Translational Study.

Background: Computed tomography is the gold standard for lung aeration assessment, but exposure to ionizing radiation limits its application. We assessed the ability of magnetic resonance imaging (MRI) to detect changes in lung aeration in ex vivo isolated swine lung and the potential of translation of the findings to human MRI scans. Methods: We performed MRI scans in 11 isolated non-injured and injured swine lungs, as well as 6 patients both pre- and post-operatively. Images were obtained using a 1.5 T MRI scanner, with T1 - weighted volumetric interpolated breath-hold examination (VIBE) and T2 - weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences. We scanned swine lungs, with reference samples of water and muscle, at different airway pressure levels: 0, 40, 10, 2 cmH2O. We investigated the relations between MRI signal intensity and both lung density and gas content fraction. We analyzed patients' images according to the findings of the ex vivo model. Results: In the ex vivo samples, the lung T1 - VIBE signal intensity normalized to water or muscle reference signal correlated with lung density (r2 = 0.98). Thresholds for poorly and non-aerated lung tissue, expressed as MRI intensity attenuation factor compared to the deflated lung, were estimated as 0.70 [95% CI: 0.65-0.74] and 0.28 [95% CI: 0.27-0.30], respectively. In patients, dorsal versus ventral regions had a higher MRI signal intensity both pre- and post-operatively (p = 0.031). Comparing post- versus pre-operative scans, lung volume decreased (p = 0.028), while the following increased: MRI signal intensity in ventral (p = 0.043) and dorsal (p < 0.0001) regions, and percentages of non-aerated (p = 0.028) and poorly aerated tissue volumes (p = 0.028). Conclusion: Magnetic resonance imaging signal intensity is a function of lung density, decreasing linearly with increasing gas content. Lung MRI might be useful for estimating lung aeration. Compared to CT, this technique is radiation-free but requires a longer acquisition time and has a lower spatial resolution.