The need for ethnic-specific reference values of lung function variables (LFs) is acknowledged. Their estimation requires expensive and laborious examinations, and therefore additional use of results in physiology and epidemiology would be profitable. To this end, we proposed a form of prediction equations with physiologically interpretable coefficients: a baseline, the onset age (A0) and rate (S) of LF decline, and a height coefficient. The form was tested with data from healthy, nonsmoking Poles aged 18-85 yr (1,120 men, 1,625 women) who performed spirometry maneuvers according to American Thoracic Society criteria. The values of all the coefficients (also A0) for several LFs were determined with regression of LF on patient's age and deviation of patient's height from the mean height in the year group of this patient. S values for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow, and maximal expiratory flow at 75% of FVC (MEF75) were very similar in both sexes (1.03+/-0.07%/yr). FEV1/FVC declines four to five times slower. S for MEF25 appeared age dependent. A0 was smallest (28-32 yr) for MEF25 and FEV1. About 50% of each age subgroup (18-40, 41-60, 61-85 yr) exhibited LFs below the mean, and 4-6% were below the 5th percentile lower limits of normal, and thus the form of equations proposed in the paper appeared appropriate for spirometry. Additionally, if this form is accepted, epidemiological and physiological comparison of different LFs and populations will be possible by means of direct comparison of the equation coefficients.

Background Due to economic and ethical problems, virtual organs may appear more convenient than experiments on animals or limited investigations on patients. In particular, a virtual respiratory system (VRS) may be useful for tasks such as respirators and support methods testing, education, staff (medical and technical) training, (initial) testing of scientific hypotheses. Methods A comparative study of simulated and real spirometric results for different patient states (healthy lungs, restrictive lung disease, and obstructive lung disease of different localization and degree) was performed. The volume-flow curve and such standard parameters as FEV1, FEV1%VC, MEF75 etc. were analyzed. Results A mathematical description of collapsing bronchi was proposed. All fundamental phenomena present during spirometry also appeared in VRS, especially characteristic dependence between lung volume and air flow for forced expiration. In particular, both airway resistance and the flow limitation were described with one formula derived from commonly known dependence of the resistance on lung volume. Generally there were no significant differences between simulated results and those seen in clinical practice. Only simulation of obstruction in upper airways gave incorrect results, which suggested a different flow limitation mechanism (perhaps wave-speed limitation). Conclusions Our VRS can already be used in medical education, e.g. courses of spirometry, and in some other applications. It seems that the significance of the wave-speed criterion has been overestimated.

Background: Measurement of intrapleural pressure is useful during various pleural procedures. However, a pleural manometer is rarely available. Objectives: The aim of this study was to (1) construct an electronic pleural manometer, (2) assess the accuracy of the measurements done with the new device, (3) calculate the costs of the manometer construction and (4) perform an initial evaluation of the device in a clinical setting. Methods: Only widely accessible elements were used to construct the device. A vascular pressure transducer was used to transform pressure into an electronic signal. Reliability of the measurements was evaluated in a laboratory setting in a prospective, single-blind manner by comparing the results with those measured by a water manometer. Functionality of the device was assessed during therapeutic thoracentesis. The cost of the new pleural manometer was calculated. Results: We built a small, portable device which can precisely measure intrapleural pressure. The measurement results showed very high agreement with those registered with a water manometer (r = 0.999; p < 0.001). The initial evaluation of the electronic manometer during therapeutic thoracentesis showed it was easy to use. The total time needed for 6 measurements after withdrawal of different volumes of pleural fluid in 1 patient did not exceed 6 min. The total cost of the device was calculated to be <2,000 EUR. Conclusions: In the face of very limited offer of commercially available pleural manometers, it is possible to successfully construct a self-made, reliable, electronic pleural manometer at modest costs. The device is easy to use and enables data display and storage in the personal computer.

We report intriguing preliminary observations on the effect of cough on pleural pressure changes during therapeutic thoracentesis. We found that cough-related elevation of pleural pressure persisted even when the cough had stopped. Thus, we hypothesize that cough during therapeutic thoracentesis may have a beneficial effect preventing the excessive drop in pleural pressure. The true role of cough-related elevation of pleural pressure is unknown, but it seems to be an interesting subject for further research.

Experiments in silico are very useful in analyzing sophisticated physiological and medical problems. They made it possible to show which factors are particularly responsible for changes in Pp during thoracentesis. In the future, they may be useful in establishing objective conditions under which thoracentesis needs to be stopped.

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Introduction: Prediction equations proposed by the European Community of Steel and Coal (ECSC) and the European Respiratory Society (ERS) or those proposed by Falaschetti et al. for the English population are currently recommended for use in Poland. The aim of the present study was to compare these equations with those developed by Lubiński and Gólczewski for the Polish population—both in terms of methodological correctness and appropriateness to the present Polish population. Materials and methods: The ECSC/ERS prediction equations, the Falaschetti equations, and the Polish equations (developed on the basis of data on healthy, non-smoking Poles aged 18 to 85 years [1120 men and 1625 women] who underwent spirometry in accordance with the American Thoracic Society [ATS]/ERS recommendations) were compared in terms of methodological correctness. Results: The main flaws in the ECSC/ERS equations include: (a) the a priori assumption that the age from which a given pulmonary function parameter (PFP) begins to decline is the same for all the PFPs and is equal to 25 years; (b) the fact that a single linear equation may not correctly describe age-related changes beyond the age of 25 years; (c) the fact that the lower limits of normal are defined by equations for the mean values minus 1.645 × SD (where SD is the standard deviation for differences between the observed and the expected values); and (d) the fact that the equations were developed a long time ago for previous generations and old spirometry procedures. The main flaws in the Falaschetti equations include: (a) excessive and unnecessary non-linearity of the equations; and (b) inadequate selection of the general population sample (insufficient number of elderly subjects) causing overestimation of forced expiratory volume in one second (FEV1) to forced vital capacity (FVC) ratio in elderly subjects. The equations proposed by Lubiński and Golczewski are free from these flaws. In particular, age distribution in the sample was uniform. Moreover, with reference to each of the PFPs: (a) the age from which a given PFP began to decline was mathematically determined together with the other coefficients of the equations; and (b) the statistical significance of the non-linearity of the relationship between age and each of the individual PFPs was analysed. What is more, in the case of the oldest subjects, the Lubiński equations yielded identical results to those obtained by other authors who had thoroughly analysed PFPs in the elderly. Conclusions: The comparison presented in this paper suggests that the equations proposed by Lubiński and Gólczewski should be used in Poland rather than those proposed by ECSC/ERS or Falaschetti et al.

Therapeutic thoracentesis may cause both an increase and a decrease in PaO during the procedure. Pleural pressure decrease, caused by pleural fluid withdrawal, improves the perfusion of atelectatic lung areas. If the rate of recruitment of these areas is low, a lack of ventilation causes the arterial blood oxygen tension to fall. Effective hypoxic pulmonary vasoconstriction may protect against the pulmonary shunt.