640 research outputs found
Quantification of Volatile Acetone Oligomers Using Ion-Mobility Spectrometry
Background. Volatile acetone is a potential biomarker that is elevated in various disease states. Measuring acetone in exhaled
breath is complicated by the fact that the molecule might be present as both monomers and dimers, but in inconsistent ratios.
Ignoring the molecular form leads to incorrect measured concentrations. Our first goal was to evaluate the monomer-dimer ratio
in ambient air, critically ill patients, and rats. Our second goal was to confirm the accuracy of the combined (monomer and dimer)
analysis by comparison to a reference calibration system. Methods. Volatile acetone intensities from exhaled air of ten intubated,
critically ill patients, and ten ventilated Sprague-Dawley rats were recorded using ion-mobility spectrometry. Acetone concentrations in ambient air in an intensive care unit and in a laboratory were determined over 24 hours. )e calibration reference
was pure acetone vaporized by a gas generator at concentrations from 5 to 45 ppbv (parts per billion by volume). Results. Acetone
concentrations in ambient laboratory air were only slightly greater (5.6 ppbv; 95% CI 5.1â6.2) than in ambient air in an intensive
care unit (5.1 ppbv; 95% CI 4.4â5.5; p < 0.001). Exhaled acetone concentrations were only slightly greater in rats (10.3 ppbv; 95% CI
9.7â10.9) than in critically ill patients (9.5 ppbv; 95% CI 7.9â11.1; p < 0.001). Vaporization yielded acetone monomers
(1.3â5.3 mV) and dimers (1.4â621 mV). Acetone concentrations (ppbv) and corresponding acetone monomer and dimer intensities (mV) revealed a high coefficient of determination (R2 ïżœ 0.96). )e calibration curve for acetone concentration (ppbv) and
total acetone (monomers added to twice the dimers; mV) was described by the exponential growth 3-parameter model, with an
R2 ïżœ 0.98. Conclusion. )e ratio of acetone monomer and dimer is inconsistent and varies in ambient air from place-to-place and
across individual humans and rats. Monomers and dimers must therefore be considered when quantifying acetone. Combining
the two accurately assesses total volatile acetone
Preparing for the SARS-CoV-2 pandemic: creation and implementation of new recommendations
During the SARS-CoV-2 pandemic in 2020, departments of anesthesiology worldwide have encountered new and unique challenges. In this short communication, we present and assess our recommendations for orotracheal intubation, a frequent high-risk procedure. We will point out that interdisciplinary cooperation with ânon-patient careâ departments like the Institute for Medical Microbiology and Hygiene tremendously helped us in creating this and other new, clear standards for anesthesiological procedures. Moreover, to reliably implement our newly created measures, we distributed incisive posters and organized comprehensive training sessions. Eventually, we summarize and analyze the occurring problems of our suggestions for intubation during their realization
Bots - Nicht-menschliche Mitglieder der Wikipedia-Gemeinschaft
"Empirische Befunde zur hybriden Wissensgenerierung am Beispiel der deutschsprachigen Wikipedia. Bisherige (soziologische) Forschungsarbeiten zu Wikipedia konzentrieren sich insbesondere auf die Frage nach der Entstehung eines eigentlich ''unmöglichen' öffentlichen Gut(s)' (Stegbauer 2006: 228), sowie auf die Entstehung von positionalen Strukturen innerhalb der Wikipedia-Gemeinschaft. Bei einer nĂ€heren Betrachtung der Edits, also den VerĂ€nderungen an Wikipedia-Artikeln, zeigt sich, dass inzwischen zahlreiche Edits von autonomen Softwareagenten, sogenannten Bots, durchgefĂŒhrt werden. Es handelt sich bei diesen Editierungen zwar ĂŒberwiegend um kleinere Ănderungen an Artikeln, dennoch ist eine zunehmende Bedeutung nicht-menschlicher Akteure fĂŒr die hybride Wissensgenerierung evident. Die Arbeit wird zunĂ€chst eine empirische Bestandsaufnahme der Bot- AktivitĂ€ten vornehmen. Dabei werden die Bots nach unterschiedlichen TĂ€tigkeitsfeldern klassifiziert und es wird untersucht, ob und wie sich die Bot-AktivitĂ€ten in den letzten Jahren intensiviert haben. Im zweiten Schritt wird das Verhalten der Bots mit dem Verhalten menschlicher Wikipedia-Nutzer verglichen und auf wesentliche Differenzen und Ăhnlichkeiten hingewiesen. Bei diesem Vergleich werden insbesondere die Art der Artikel-Ănderungen und der Umfang der Ănderungen berĂŒcksichtigt. AbschlieĂend wird der Versuch unternommen, das Zusammenhandeln von Bot, Bot- Betreiber und Wikipedia-Nutzer mit Hilfe eines hybriden Handlungsmodells (HMSE) (Fink/Weyer 2010) zu erklĂ€ren." (Autorenreferat
Plasma Disappearance Rate of Indocyanine Green for Determination of Liver Function in Three Different Models of Shock
The measurement of the liver function via the plasma disappearance rate of indocyanine
green (PDRICG) is a sensitive bed-side tool in critical care. Yet, recent evidence has questioned the value
of this method for hyperdynamic conditions. To evaluate this technique in different hemodynamic
settings, we analyzed the PDRICG and corresponding pharmacokinetic models after endotoxemia or
hemorrhagic shock in rats. Male anesthetized Sprague-Dawley rats underwent hemorrhage (mean
arterial pressure 35 ± 5 mmHg, 90 min) and 2 h of reperfusion, or lipopolysaccharide (LPS) induced
moderate or severe (1.0 vs. 10 mg/kg) endotoxemia for 6 h (each n = 6). Afterwards, PDRICG was
measured, and pharmacokinetic models were analyzed using nonlinear mixed effects modeling
(NONMEMÂź). Hemorrhagic shock resulted in a significant decrease of PDRICG, compared with sham
controls, and a corresponding attenuation of the calculated ICG clearance in 1- and 2-compartment
models, with the same log-likelihood. The induction of severe, but not moderate endotoxemia, led to
a significant reduction of PDRICG. The calculated ICG blood clearance was reduced in 1-compartment
models for both septic conditions. 2-compartment models performed with a significantly better log
likelihood, and the calculated clearance of ICG did not correspond well with PDRICG in both LPS
groups. 3-compartment models did not improve the log likelihood in any experiment. These results
demonstrate that PDRICG correlates well with ICG clearance in 1- and 2-compartment models after
hemorrhage. In endotoxemia, best described by a 2-compartment model, PDRICG may not truly
reflect the ICG clearance
Increased Respiratory Drive after Prolonged Isoflurane Sedation : A Retrospective Cohort Study
Low-dose isoflurane stimulates spontaneous breathing. We, therefore, tested the hypothesis
that isoflurane compared to propofol sedation for at least 48 h is associated with increased respiratory
drive in intensive care patients after sedation stop. All patients in our intensive care unit receiving
at least 48 h of isoflurane or propofol sedation in 2019 were included. The primary outcome was
increased respiratory drive over 72 h after sedation stop, defined as an arterial carbon dioxide pressure
below 35 mmHg and a base excess more than â2 mmol/L. Secondary outcomes were acidâbase
balance and ventilatory parameters. We analyzed 64 patients, 23 patients sedated with isoflurane and
41 patients sedated with propofol. Patients sedated with isoflurane were about three times as likely
to show increased respiratory drive after sedation stop than those sedated with propofol: adjusted
risk ratio [95% confidence interval]: 2.9 [1.3, 6.5], p = 0.010. After sedation stop, tidal volumes
were significantly greater and arterial carbon dioxide partial pressures were significantly lower,
while respiratory rates did not differ in isoflurane versus propofol-sedated patients. In conclusion,
prolonged isoflurane use in intensive care patients is associated with increased respiratory drive after
sedation stop. Beneficial effects of isoflurane sedation on respiratory drive may, thus, extend beyond
the actual period of sedation
Exhaled Aldehydes as Biomarkers for Lung Diseases : A Narrative Review
Breath analysis provides great potential as a fast and non-invasive diagnostic tool for
several diseases. Straight-chain aliphatic aldehydes were repeatedly detected in the breath of patients
suffering from lung diseases using a variety of methods, such as mass spectrometry, ion mobility
spectrometry, or electro-chemical sensors. Several studies found increased concentrations of exhaled
aldehydes in patients suffering from lung cancer, inflammatory and infectious lung diseases, and
mechanical lung injury. This article reviews the origin of exhaled straight-chain aliphatic aldehydes,
available detection methods, and studies that found increased aldehyde exhalation in lung diseases
Three-Dimensional Software- and MR-Imaging-Based Muscle Volumetry Reveals Overestimation of Supraspinatus Muscle Atrophy Using Occupation Ratios in Full-Thickness Tendon Tears
Supraspinatus muscle atrophy is widely determined from oblique-sagittal MRI by calculating the occupation ratio. This ex vivo and clinical study aimed to validate the accuracy of 3D software- and MR-imaging-based muscle volumetry, as well as to assess the influence of the tear pattern on the occupation ratio. Ten porcine muscle specimens were volumetrized using the physical water displacement volumetry as a standard of reference. A total of 149 individuals with intact supraspinatus tendons, partial tears, and full-thickness tears had 3T MRI. Two radiologists independently determined occupation ratio values. An excellent correlation with a Pearson's r of 0.95 for the variables physical volumetry using the water displacement method and MR-imaging-based muscle volumetry using the software was found and formed the standard of reference for the patient study. The inter-reader reliability was 0.92 for occupation ratios. The correlation between occupation ratios and software-based muscle volumes was good in patients with intact tendons (0.84) and partial tears (0.93) but considerably lower in patients with full-thickness tears (0.68). Three-dimensional-software- and MR-imaging-based muscle volumetry is reliable and accurate. Compared to 3D muscle volumetry, the occupation ratio method overestimates supraspinatus muscle atrophy in full-thickness tears, which is most likely due to the medial retraction of the myotendinous unit
Quantification of Volatile Aldehydes Deriving from In Vitro Lipid Peroxidation in the Breath of Ventilated Patients
Exhaled aliphatic aldehydes were proposed as non-invasive biomarkers to detect increased
lipid peroxidation in various diseases. As a prelude to clinical application of the multicapillary
columnâion mobility spectrometry for the evaluation of aldehyde exhalation, we, therefore: (1) identified the most abundant volatile aliphatic aldehydes originating from in vitro oxidation of various
polyunsaturated fatty acids; (2) evaluated emittance of aldehydes from plastic parts of the breathing
circuit; (3) conducted a pilot study for in vivo quantification of exhaled aldehydes in mechanically
ventilated patients. Pentanal, hexanal, heptanal, and nonanal were quantifiable in the headspace of
oxidizing polyunsaturated fatty acids, with pentanal and hexanal predominating. Plastic parts of
the breathing circuit emitted hexanal, octanal, nonanal, and decanal, whereby nonanal and decanal
were ubiquitous and pentanal or heptanal not being detected. Only pentanal was quantifiable in
breath of mechanically ventilated surgical patients with a mean exhaled concentration of 13 ± 5 ppb.
An explorative analysis suggested that pentanal exhalation is associated with mechanical powerâa
measure for the invasiveness of mechanical ventilation. In conclusion, exhaled pentanal is a promising non-invasive biomarker for lipid peroxidation inducing pathologies, and should be evaluated in
future clinical studies, particularly for detection of lung injury
- âŠ