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A possible clinical application of electrical impedance tomography (EIT) might be to monitor changes in the pulmonary circulation, provided the reproducibility of the EIT measurement is adequate. The purpose of this study was threefold: the intra- and inter-investigator variability of repeated measurements was investigated. Three different regions of interest (ROI) were analysed to assess the optimal ROI. Twenty-four healthy subjects and six patients were included. The Sheffield applied potential tomograph (DAS-01P, IBEES, Sheffield, UK) was used. Electrodes were attached by investigator A, and duplicate EIT measurements were performed. After detachment and 45 min of rest, the protocol was repeated by another investigator B, and afterwards by the initial investigator A. Three ROIs were analysed: whole circle, 'inner half circle' and contour. The mean difference in impedance changes between observers is presented in arbitrary units (AU) +/- SD. Finally, the influence of age, body composition and sex on the EIT result was examined. For the contour ROI, the mean difference for the intra-investigator situation was -1.44 x 10(-2) +/- 18.45 x 10(-2) AU (-0.7 +/- 9.0%), and was 5.46 x 10(-2) +/- 21.66 x 10(-2) AU (2.7 +/- 10.8%) for the inter-investigator situation. The coefficient of reproducibility of the intra- and inter-investigator reproducibility varied between 0.89 and 0.97 for all ROIs (P < 0.0001). There is a relation between impedance change and age (correlation coefficient r = -0.63, P < 0.01 for contour ROI), and between impedance change and body mass index (BMI) (r = -0.53, P < 0.05). We found a significant difference in mean impedance change between groups of males and females. In conclusion, EIT results are highly reproducible when performed by the same investigator as well as by two different investigators.

Rationale: Caffeine is present in many widely consumed drinks and some foods. In the fairly extensive literature on the psychostimulant effects of caffeine, there are few dose-response studies and even fewer studies of the effects of doses of caffeine lower than 50 mg (the range of the amounts of caffeine contained in, for example, a typical serving of tea or cola)., Objective: This study measured the effects of 0, 12.5, 25, 50 and 100 mg caffeine on cognitive performance, mood and thirst in adults with low and moderate to high habitual caffeine intakes., Methods: This was a double-blind, within-subjects study. Following overnight caffeine abstinence, participants (n=23) completed a test battery once before and three times after placebo or caffeine administration. The test battery consisted of two performance tests, a long duration simple reaction time task and a rapid visual information processing task, and a mood questionnaire (including also an item on thirst)., Results: Effects on performance and mood confirmed a psychostimulant action of caffeine. All doses of caffeine significantly affected cognitive performance, and the dose-response relationships for these effects were rather flat. The effects on performance were more marked in individuals with a higher level of habitual caffeine intake, whereas caffeine increased thirst only in low caffeine consumers., Conclusions: After overnight caffeine abstinence, caffeine can significantly affect cognitive performance, mood and thirst at doses within and even lower than the range of amounts of caffeine contained in a single serving of popular caffeine-containing drinks. Regular caffeine consumers appear to show substantial tolerance to the thirst-increasing but not to the performance and mood effects of caffeine.

Study Aims: To examine the influence of atmospheric pressure (AP) and temperature changes on the incidence of idiopathic spontaneous pneumothorax (SP)., Methods: From December 1991 through November 1993, 115 consecutive SP cases were selected. Patients were included after being in Amsterdam at least 1 full day before contracting the SP. Differences in air temperature and AP (provided hourly by the national weather bureau) for the days of the SP occurrence and the days previous to it were recorded to measure influences of air temperature and AP. The correlation between days with lightning and SP and clustering of SP was evaluated., Results: SP occurred on 14.7% of the days in the 2-year period. There was no relationship between SP and a rise or fall in AP (Poisson regression). There was an average temperature rise of 0.57 degrees C from the day prior to the day of the SP, compared with a 0.08 degrees C fall on the days without SP. This difference is statistically significant and was consistent over the four seasons and both years. Seventy-three percent of the SP cases were clustered. A relationship between SP and thunderstorms was found., Conclusions: AP differences do not seem to influence the chance of developing SP. SP occurs in clusters, and more often 1 to 2 days after thunderstorms. Whether the identified temperature rise prior to the SP is a causative factor is unlikely; coexisting weather phenomena might explain this unexpected finding and should be studied in the future.

Pleural fluid analysis was performed in patients with idiopathic spontaneous pneumothorax. The objective of the study was to define the cell differentiation, and part of the cytokine profile, in relation to the duration of pneumothorax. In the 23 consecutive patients (19 men, mean age 34.2 years, 17 smokers), pleural fluid was obtained immediately after chest tube drainage (n = 6), or during thoracoscopy (n = 17). Cytospins were carried out, and supernatant analysis of the different cytokines was performed using sandwich ELISA. All concentrations were corrected for dilution. The duration of the pneumothorax was correlated with the rise in eosinophil percentage (r = 0.81, P < 0.00001) in pleural fluid. RANTES, platelet-activating factor (PAF), and monocyte chemotactic protein-1 (MCP-1) were detectable but no relationship with eosinophils or duration of the pneumothorax was found. Granulocyte-macrophage colony stimulating factor (GM-CSF) and interluekin-8 (IL-8) were not detectable. Interleukin-5 (IL-5) concentration correlated with the eosinophil concentration (r = 0.84, P = 0.037) and the eosinophil percentage (r = 0.68, P = 0.005) in the pleural fluid. Idiopathic spontaneous pneumothorax causes a time-related rise in the eosinophil percentage in the pleural space, which correlates with the level of IL-5.

Talc administration into the pleural cavity induces pleurodesis. To obtain further insight into the inflammatory process that causes pleurodesis, the cellular kinetics in the pleural space after the administration of talc was studied, along with its relation to chemokine concentrations in the pleural fluid. Thirteen consecutive patients with idiopathic spontaneous pneumothorax and eight patients with malignant pleural effusions received talc pleurodesis. The first group was treated with talc poudrage, whereas the second group was treated with talc slurry. Pleural fluids were isolated before talc administration as well as 3, 6, 24, 48 and 72 h afterwards. The talc induced a rapid polymorphonuclear neutrophil (PMN) influx followed by an accumulation of macrophages. In addition, increased production of interleukin (IL)-8 and monocyte chemotactic protein (MCP)-1 was observed. The talc-induced PMN influx reached its maximum after 3-24 h, and was related to the IL-8 concentration. In contrast, the MCP-1 was not related to the macrophage accumulation. Talc-induced inflammation in patients with idiopathic spontaneous pneumothorax and malignant pleural effusion is characterized by an influx of polymorphonuclear neutrophils related to interleukin-8, followed by an accumulation of monocytes.

The pneumothorax, and its often invasive treatment, are impressive events in otherwise healthy young patients. The relationship between smoking behaviour and the idiopathic spontaneous pneumothorax (ISP) is explained to the patients. The objective of the study was to analyse whether smoking behaviour of patients is influenced by the ISP (re-) event, and its treatment. Of 145 consecutive ISP patients (1991-1995), 112 were tobacco smokers at time of the first ISP. Of the 112, 106 participated in a confidential telephone questionnaire survey combined with retrospective medical record analysis. Smoking cessation and reduction percentage related to ISP events, and its treatment, were the outcome measurements. All patients (mean age 28.8 years at the first ISP) were aware of the relationship between smoking, and ISP at time of the first ISP. Age, pack years, and different treatment modalities had no influence on smoking cessation or reduction. Some 86.2% of the male and 80.8% of the female patients continued smoking after the first ISP, despite the known relationship between smoking, and contracting spontaneous pneumothorax, and despite its often invasive treatment. In the group of recurrent pneumothorax events 73.3% continued smoking.

Unlabelled: Video-assisted thoracoscopy (VAT) is usually performed under general anesthesia (GA). We performed an analysis to determine whether multithoracoport VAT under local anesthesia (LA) is feasible., Methods: Forty-five VAT under LA were performed in 34 men and 11 women (mean age 46.8 years) in the endoscopy room., Results: The waiting time for VAT under LA was 0.5-6h on working days. There were no major complications during or after the VAT. In 9 patients, pleural malignancy was diagnosed, and in 7 patients suspected malignancy was excluded. In 5 patients we found bacterial empyema, of whom 4 had diathermic adhesiolysis during VAT. In 4 patients, the clinical diagnosis was tuberculosis by exclusion, and in 2 patients no conclusive diagnosis could be drawn. VAT influenced treatment policy 15 times, and in 17 pneumothorax patients talc poudrage was performed during the procedure., Conclusion: VAT under LA is safe, effective, logistically simple, and requires no long waiting times. No conversion to GA was necessary.

A retrospective study of 21 patients with primary ciliary dyskinesia (PCD) was done. Thirteen had prior resection of bronchiectasis and eight had not. Information about present complaints was obtained by a questionnaire. The prevalence of present respiratory symptoms was the same in both groups. The surgical patients had more severe disease and 85% of them considered the operation beneficial. Selected patients with PCD may have improved conditions with resection of bronchiectasis.