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Purpose The study aims to prospectively validate the prognostic value of oximetry alone or combined in a two-step strategy with a questionnaire for the exclusion of obstructive sleep apnea (OSA) in primary care. Methods A total of 140 subjects with suspected OSA were included from 54 participating primary care practices. All subjects completed the Philips questionnaire and underwent one night of oximetry prior to referral to a sleep center. The prognostic value of two strategies was evaluated against the diagnosis of the sleep center as the gold standard: (1) assume OSA and subsequently refer to a sleep center if the oxygen desaturation index (ODI) is ≥ 5 and (2) assume OSA and refer to a sleep center if the Philips questionnaire score is ≥ 55% (regardless of the ODI) or if the Philips questionnaire score is

In this study, the hypercapnic ventilatory response (HCVR) was measured, defined as the ventilation response to carbon dioxide tension (PCO2). We investigated which method, rebreathing or steady-state, is most suitable for measurement of the HCVR in healthy subjects, primarily based on reproducibility. Secondary outcome parameters were subject experience and duration. 20 healthy adults performed a rebreathing and steady-state HCVR measurement on two separate days. Subject experience was assessed using numeric rating scales (NRS). The intraclass correlation coefficient (ICCs) of the sensitivity to carbon dioxide above the ventilatory recruitment threshold and the projected apnoea threshold were calculated to determine the reproducibility of both methods. The ICCs of sensitivity were 0.89 (rebreathing) and 0.56 (steady-state). The ICCs of the projected apnoea threshold were 0.84 (rebreathing) and 0.25 (steady-state). The steady-state measurement was preferred by 16 out of 20 subjects; the differences in NRS scores were small. The hypercapnic ventilatory response measured using the rebreathing setup provided reproducible results, while the steady-state method did not. This may be explained by high variability in end-tidal PCO2. Differences in subject experience between the methods are small., The hypercapnic ventilatory response measured by a rebreathing setup is reproducible, as opposed to a steady-state setup http://ow.ly/yGDg30hStIB

The most important function of the lungs is gas exchange. They are able to do so due to a sophisticated balance between ventilation and perfusion. Examples of diseases with a ventilation / perfusion mismatch are acute pulmonary embolism (PE, i.e. blood clots causing (partial) blockage of the pulmonary arteries) and obstructive sleep apnea (OSA, i.e. repetitive breathing stops during sleep due to collapse of the upper airway). In both cases novel diagnostic tools are warranted. The research presented in this thesis focused on the development of novel diagnostic tools using the consequences of ventilation / perfusion mismatches in PE and OSA. For the exclusion of PE at the emergency department, the usability of volumetric capnography and combined measurement of the transfer factor of the lungs for nitric oxide (TLNO) and carbon monoxide (TLCO) were investigated. There was no difference in TLNO / TLCO ratio between subjects with and without PE whereas a novel volumetric capnography derived parameter showed promising results. External validation however showed that this parameter was indeed significantly decreased in subjects with PE but its diagnostic accuracy was too low to allow its use in clinical practice. To be able to find novel strategies to exclude OSA without the need for laborious and expensive tests (e.g. poly(somno)graphy), the oxygen desaturation index (ODI) and the apnea hypopnea index (AHI) were compared in a large polygraphy database. This showed that an ODI < 5 excludes OSA (defined as an AHI ≥ 5) with high certainty. Subsequently, a strategy using a questionnaire and oximetry to exclude OSA in primary care was prospectively validated. As hypothesized, this strategy (i.e. refer to a sleep center if either the oximetry or the questionnaire is aberrant) enabled reliable exclusion of OSA. Another potential tool for the exclusion of OSA was the measurement of exhaled breath profiles using an electronic nose. Though there was a significant relationship between the exhaled breath profiles and the AHI, the profiles could not be used to reliable classify subjects into OSA or non-OSA.

Introduction: Obstructive sleep apnea (OSA) is common, and diagnosis requires expensive and laborious testing to assess the apnea hypopnea index (AHI). We performed an analysis to explore the relationship between the oxygen desaturation index (ODI) as measured with pulse oximetry and the AHI in our large portable monitoring (PM) database to find an optimal cutoff value for the ODI in order to be able to exclude AHI ≥ 5 on PM. Methods: Three thousand four hundred thirteen PM recordings were randomly divided into a training set (N = 2281) and a test set (N = 1132). The optimal cutoff for the ODI to exclude an AHI ≥ 5 on PM was determined in the training set and subsequently validated in the test set. Results: Area under the curve of the ODI to exclude an AHI ≥ 5 on PM was 0.997 in the training set and 0.996 in the test set. In the training set, the optimal cutoff to predict an AHI < 5 was an ODI < 5. Using this cutoff in the test set provided a sensitivity of 97.7%, a specificity of 97.0%, a positive predictive value of 99.2%, and a negative predictive value of 91.4%. Conclusion: An ODI < 5 predicts an AHI < 5 with high sensitivity and specificity when measured simultaneously using the same oximeter during PM recording.

Contains fulltext : 165971.pdf (Publisher’s version ) (Open Access) A noncontact mapping system (EnSite) was used for electroanatomical mapping of the bladder simultaneously with pressure flow study in three women with lower urinary tract symptoms. We selected the periods of obvious detrusor activity. Data were processed to remove baseline drift, and an envelope of electrovesicography (EVG) data was created. The correlation coefficient for the correlation between between the EVG envelope and the detrusor pressure (Pdet) was calculated. Bladder geometry was successfully created in all 3 patients. Simultaneous recording of EVG and pressure flow data was successful in 1 patient. Scatter plots were made of the highest correlation coefficient, showing a positive correlation between the Pdet and the envelope, and negative correlation between abdominal pressure (Pabd) and the envelope. Minimal electrical activity could be observed. Significant weak to moderate correlation coefficients were found for the correlations between Pdet and EVG and between Pabd and EVG.