26 research outputs found
Methodological considerations for large-scale breath analysis studies : lessons from the U-BIOPRED severe asthma project
Methods for breath sampling and analysis require robust quality assessment to minimise the risk of false discoveries. Planning large-scale multi-site breath metabolite profiling studies also requires careful consideration of systematic and random variation as a result of sampling and analysis techniques. In this study we use breath sample data from the recent U-BIOPRED cohort to evaluate and discuss some important methodological considerations such as batch variation and correction, variation between sites, storage and transportation, as well as inter-instrument analytical differences. Based on this we provide a summary of recommended best practices for new large scale multi-site studies
Horizon detection based on sky-color and edge features
Horizon detection in still images or video sequences contributes to applications like image understanding, automatic correction of image tilt and image quality enhancement. In this paper, we propose an algorithm for detecting the horizon line in digital images, which employs an edge-based and a new color-based horizon detection technique. The color-based detector calculates an estimate of the horizon line by analyzing the color transition in the clear sky areas of the image. The edge-based detector computes the horizon line by finding the most prominent line or edge in the image, based on Canny edge detection and Hough transformation. The proposed algorithm combines the two detectors into a hybrid detection system, thereby taking advantage of their complimentary strengths. We have applied the algorithm on a manually annotated set of images and evaluated the accuracy of the position and angle of the detected horizon line. The experiments indicate the usefulness of the proposed color-based detector (40% lower error vs. the edge-based detector) and the benefit of the adopted approach for combining the two individual detectors (57% and 17% lower error vs. the edge-based and the color-based detectors, respectively)
Automatic mashup generation from multiple-camera concert recordings
A large number of videos are captured and shared by the audience from musical concerts. However, such recordings are typically perceived as boring mainly because of their limited
view, poor visual quality and incomplete coverage. It is our objective to enrich the viewing experience of these recordings by exploiting the abundance of content from multiple
sources. In this paper, we propose a novel Virtual Director system that automatically combines the most desirable segments from different recordings resulting in a single video
stream, called mashup. We start by eliciting requirements from focus groups, interviewing professional video editors and consulting film grammar literature. We design a formal
model for automatic mashup generation based on maximizing the degree of fulfillment of the requirements. Various audio-visual content analysis techniques are used to determine
how well the requirements are satisfied by a recording. To validate the system, we compare our mashups with two other mashups: manually created by a professional video
editor and machine generated by random segment selection. The mashups are evaluated in terms of visual quality, content diversity and pleasantness by 40 subjects. The results
show that our mashups and the manual mashups are perceived as comparable, while both of them are significantly higher than the random mashups in all three terms
Volatile organic compound signature from co-culture of lung epithelial cell line with Pseudomonas aeruginosa
Bacterial volatile organic compounds have the potential to be utilised as diagnostic biomarkers for infections.</p
A strategy to reduce critical cardiorespiratory alarms due to intermittent enteral feeding of reterm neonates in intensive care
\u3cp\u3eBACKGROUND: Many preterm infants require enteral feeding as they cannot coordinate sucking, swallowing, and breathing. In enteral feeding, milk feeds are delivered through a small feeding tube passed via the nose or mouth into the stomach. Intermittent milk feeds may either be administered using a syringe to gently push milk into the infant's stomach (push feed) or milk can be poured into a syringe attached to the tube and allowed to drip in by gravity (gravity feed). This practice of enteral feeding is common in neonatal intensive care units. There is, however, no evidence in the literature to recommend the use of one method of feeding over the other.\u3c/p\u3e\u3cp\u3eOBJECTIVE: The aim of this study was to investigate which of the two methods of feeding is physiologically better tolerated by infants, as measured by the incidence of critical cardiorespiratory alarms during and immediately after feeding.\u3c/p\u3e\u3cp\u3eMETHODS: We conducted a prospectively designed observational study with records of all feeding episodes in infants of gestational age less than 30 weeks at birth and with a minimum enteral intake of 100 mL/kg/day. In total, 2140 enteral feeding episodes were noted from 25 infants over 308 infant-days with records for several characteristics of the infants (eg, gestational age), feeding (eg, the position of infants), and of nursing-care events before feeding (eg, diapering). Logistic regression with mixed effects was used to model cardiorespiratory alarms for the push and gravity methods of feeding.\u3c/p\u3e\u3cp\u3eRESULTS: After adjustments were made for all confounding variables, the position of infants was found to be statistically significant in changing the outcome of critical alarms for the two methods of feeding (P=.02). For infants in the lateral position, push feeds led to 40% more instances of one or more critical cardiorespiratory alarms in comparison with the gravity method. Both methods of feeding created a statistically comparable number of alarms for infants in the prone position.\u3c/p\u3e\u3cp\u3eCONCLUSIONS: This study provides objective data that may assist in optimizing enteral feeding protocols for premature infants. The incidence of critical cardiorespiratory alarms for infants in the lateral position can be lowered by the use of gravity instead of push feeding. No differences were observed between the two types of feeding when infants were in the prone position.\u3c/p\u3
Exhaled breath metabolomics as a noninvasive diagnostic tool for acute respiratory distress syndrome
There is a need for biological markers of the acute respiratory distress syndrome (ARDS). Exhaled breath contains hundreds of metabolites in the gas phase, some of which reflect (patho)physiological processes. We aimed to determine the diagnostic accuracy of metabolites in exhaled breath as biomarkers of ARDS. Breath from ventilated intensive care unit patients (n=101) was analysed using gas chromatography and mass spectrometry during the first day of admission. ARDS was defined by the Berlin definition. Training and temporal validation cohorts were used. 23 patients in the training cohort (n=53) had ARDS. Three breath metabolites, octane, acetaldehyde and 3-methylheptane, could discriminate between ARDS and controls with an area under the receiver operating characteristic curve (AUC) of 0.80. Temporal external validation (19 ARDS cases in a cohort of 48) resulted in an AUC of 0.78. Discrimination was insensitive to adjustment for severity of disease, a direct or indirect cause of ARDS, comorbidities, or ventilator settings. Combination with the lung injury prediction score increased the AUC to 0.91 and improved net reclassification by 1.17. Exhaled breath analysis showed good diagnostic accuracy for ARDS, which was externally validated. These data suggest that exhaled breath analysis could be used for the diagnostic assessment of ARD
Levels of cytokines in broncho-alveolar lavage fluid, but not in plasma, are associated with levels of markers of lipid peroxidation in breath of ventilated ICU patients
Alkanes and alkenes in the breath are produced through fatty acid peroxidation, which is initialized by reactive oxygen species. Inflammation is an important cause and effect of reactive oxygen species. We aimed to evaluate the association between fatty acid peroxidation products and inflammation of the alveolar and systemic compartment in ventilated intensive care unit (ICU) patients.Volatile organic compounds were measured by gas chromatography and mass spectrometry in the breath of newly ventilated ICU patients within 24 h after ICU admission. Cytokines were measured in non-directed bronchial lavage fluid (NBL) and plasma by cytometric bead array. Correlation coefficients were calculated and presented in heatmaps.93 patients were included. Peroxidation products in exhaled breath were not associated with markers of inflammation in plasma, but were correlated with those in NBL. IL-6, IL-8, IL-1β and TNF-α concentration in NBL showed inverse correlation coefficients with the peroxidation products of fatty acids. Furthermore, NBL IL-10, IL-13, GM-CSF and IFNγ demonstrated positive associations with breath alkanes and alkenes. Correlation coefficients for NBL cytokines were high regarding peroxidation products of n-6, n-7 and particularly in n-9 fatty acids.Levels of lipid peroxidation products in the breath of ventilated ICU patients are associated with levels of inflammatory markers in NBL, but not in plasma. Alkanes and alkenes in breath seems to be associated with an anti-inflammatory, rather than a pro-inflammatory state in the alveol
Exhaled Breath Metabolomics for the Diagnosis of Pneumonia in Intubated and Mechanically-Ventilated Intensive Care Unit (ICU)-Patients
The diagnosis of hospital-acquired pneumonia remains challenging. We hypothesized that analysis of volatile organic compounds (VOCs) in exhaled breath could be used to diagnose pneumonia or the presence of pathogens in the respiratory tract in intubated and mechanically-ventilated intensive care unit patients. In this prospective, single-centre, cross-sectional cohort study breath from mechanically ventilated patients was analysed using gas chromatography-mass spectrometry. Potentially relevant VOCs were selected with a p-value < 0.05 and an area under the receiver operating characteristics curve (AUROC) above 0.7. These VOCs were used for principal component analysis and partial least square discriminant analysis (PLS-DA). AUROC was used as a measure of accuracy. Ninety-three patients were included in the study. Twelve of 145 identified VOCs were significantly altered in patients with pneumonia compared to controls. In colonized patients, 52 VOCs were significantly different. Partial least square discriminant analysis classified patients with modest accuracy (AUROC: 0.73 (95% confidence interval (CI): 0.57-0.88) after leave-one-out cross-validation). For determining the colonization status of patients, the model had an AUROC of 0.69 (95% CI: 0.57-0.82) after leave-one-out cross-validation. To conclude, exhaled breath analysis can be used to discriminate pneumonia from controls with a modest to good accuracy. Furthermore breath profiling could be used to predict the presence and absence of pathogens in the respiratory tract. These findings need to be validated externall