Selected ion flow tube mass spectrometry (SIFT-MS) is versatile, rapidly provides result output and determines a wide range of volatiles, making it suitable for biomedical applications. When direct sampling into the SIFT-MS instrument is impractical, combining thermal desorption (TD) and SIFT-MS might offer a solution as it allows sample storage on sorbent tubes for later analysis. This work compares off-line TD SIFT-MS and real-time SIFT-MS for the quantification of selected breath volatiles. Methods: Ten healthy non-smoking individuals provided 60 breath samples per method. For off-line analysis, breath was collected onto sorbent tubes via a breath sampler provided with filtered inspiratory air. After TD, samples were recollected in Tedlar bags which were then connected to the SIFT-MS instrument. For real-time analysis, breath was sampled directly into the instrument. In both cases the analytical method included a total of 155 product ions, and 14 selected volatiles were quantified. The agreement between the methods was assessed using Pearson correlation coefficients and Bland-Altman plots. Results: Overall, correlations between real-time and off-line analysis were moderate to very strong (r = 0.43-0.92) depending on the volatile of interest, except for 2,3-butanedione and styrene. The difference between real-time and off-line measured breath concentrations (average bias) ranged between −14.57 and 20.48 ppbv. For acetone and isoprene, it was 251.53 and 31.9 ppbv, respectively. Conclusions: Real-time SIFT-MS and off-line TD SIFT-MS for quantification of selected breath volatiles did not show optimal agreement. Analyzing a multitude of analytes in breath via direct exhalation into a SIFT-MS instrument for real-time analysis is challenging. On the other hand, off-line analysis using a breath collection device also has its issues such as possible sample losses due to selective absorption depending on the sorbent used or during desorption and transfer to the instrument. Despite these drawbacks, both methods were moderately well correlated. 1 | INTRODUCTION Analytical techniques allow the measurement of volatile organic compounds (VOCs) in various media including exhaled breath. 1 Breath analysis is used for the identification, detection and quantification of volatile biomarkers related to disease. Given that the concentrations of most volatile biomarkers in exhaled breath are low, often at parts per billion by volume (ppbv) or lower, this is a challenge for analytical instrumentation which must be sufficiently accurate and precise to be useful. 2

Objective: To evaluate the efficiency of percutaneous patent foramen ovale (PFO) closure on the recurrence of decompression illness (DCI). Design: Retrospective, observational study with interview and questionnaire Setting: Tertiary referral center. Population: 59 scuba divers with a history of DCI who received a percutaneous PFO closure. Main outcome measurements: Questionnaire about health status, dive habits and recurrence of DCI after PFO closure. Results: A total of 59 divers with DCI were included. The most common manifestations of DCI were cutaneous or vestibular DCI. Procedural complications occurred in four patients but none with long-term consequences. Four patients had recurrence of DCI after closure during a 10-year follow-up. In three of these cases there was residual shunting, all of which were initially considered closed. The fourth patient had aggravating factors for his recurrent DCI. A quarter of the patients stated to have changed their diving habits. Four patients quit diving. Conclusion: Percutaneous PFO closure for secondary prevention of DCI is associated with few, but not negligible, complications. As a large portion of our cohort changed their diving habit after closure it is difficult to ascertain the efficiency of PFO closure for secondary prevention of DCI. However, the study shows that PFO closure does not fully protect against DCI, emphasizing that the relationship between PFO and DCI is but an association. As such it is imperative that divers be counseled to ensure they understand the risks as well as the benefits of percutaneous PFO closure in their specific case.

This caseemphasizes the importance of considering late postpartum eclampsia in patients presenting with signs of pulmonary edema even several days after delivery, as early diagnosis and prompt initiation of appropriate antihypertensive and anticonvulsant therapy can prevent severe complications.