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Computerized spirometry using a portable microcomputer.

The reliable conduct of pulmonary function studies, while in the field, is increasingly important as various standards mandate this activity. Versatile, portable and accurate equipment is required. A lightweight and computerized portable spirometer system is discussed, PSPIRO, which uses a standard volumetric spirometer and a briefcase-sized microcomputer. The system, compact enough to be easily moveable by one person, performs tests for FVC, FEV(1), FEV(3), the percentage of predicted pulmonary function for each, and the ratio of FEV(1)/FVC. Back extrapolation is used to establish the start of each forced expiratory maneuver, reproducibility checks are performed, and accuracy is within acceptable epidemiologic standards. A small, portable analog to digital interface (PLAD) was developed for performing A/D conversions through the RS-232C port of the portable microcomputer.

Humans↗

Spirometry and forced oscillometry assisted optimal frequency band determination for the computerized analysis of tracheal lung sounds in asthma.

We analysed respiration sounds of individual asthmatic patients, in the scope of the development of a method for computerized recognition of the degree of airway obstruction. Respiration sounds were recorded during laboratory sessions of histamine-provoked airway obstruction. We applied an interpolation technique using supervised artificial neural networks to investigate the optimal frequency band required for studying tracheal asthmatic lung sounds. The optimal band was found to be 100-2300 Hz. The forced expiratory volume in 1 s (FEV1) and the respiratory resistance parameter Rrs(4) were used to describe the degree of airway obstruction that is associated with the lung sounds. By comparing the results obtained with the two parameters, we found that for parametrization of the associated degree of airway obstruction respiratory resistance measurements are preferable over forced expiratory volume measurements.

Adult↗

Serial changes in spirometry during an ascent to 5,300 m in the Nepalese Himalayas.

The aims of the present study were to determine the changes in forced vital capacity (FVC), forced expiratory volume in 1 sec (FEV1) and peak expiratory flow (PEF), during an ascent to 5,300 m in the Nepalese Himalayas, and to correlate the changes with arterial oxygen saturation measured by pulse oximetry (SpO2) and symptoms of acute mountain sickness (AMS). Forty-six subjects were studied twice daily during an ascent from 2,800 m (mean barometric pressure 550.6 mmHg) to 5,300 m (mean barometric pressure 404.3 mmHg) during a period of between 10 and 16 days. Measurements of FVC, FEV1, PEF, SpO2, and AMS were recorded. AMS was assessed using a standardized scoring system. FVC fell with altitude, by a mean of 4% from sea level values [95% confidence intervals (CI) 0.9% to 7.4%] at 2,800 m, and 8.6% (95% CI 5.8 to 11.4%) at 5,300 m. FEV1 did not change with increasing altitude. PEF increased with altitude by a mean of 8.9% (95% CI 2.7 to 15.1%) at 2,800 m, and 16% (95% CI 9 to 23%) at 5,300 m. These changes were not significantly related to SpO2 or AMS scores. These results confirm a progressive fall in FVC and increase in PEF with increasing hypobaric hypoxia while FEV1 remains unchanged. The increase in PEF is less than would be predicted from the change in gas density. The fall in FVC may be due to reduced inspiratory force producing a reduction in total lung capacity; subclinical pulmonary edema; an increase in pulmonary blood volume, or changes in airway closure. The absence of a correlation between the spirometric changes and SpO2 or AMS may simply reflect that these measurements of pulmonary function are not sufficiently sensitive indicators of altitude-related disease. Further studies are required to clarify the effects of hypobaric hypoxia on lung volumes and flows in an attempt to obtain a unifying explanation for these changes.

Adult↗

Postoperative spirometry after laparoscopy for lower abdominal or upper abdominal surgical procedures.

In this prospective study, we have compared women undergoing laparoscopic cholecystectomy, laparoscopic gynaecological surgery and laparoscopic minor gynaecological procedures (diagnostic, tubal, ligation) (n = 10 in each group) to determine if lower abdominal laparoscopy results in less postoperative pulmonary dysfunction than upper abdominal laparoscopy. Pulmonary testing was performed before operation, and 3 and 6 h after operation, on the first and second days after surgery. After operation, a significant reduction in forced vital capacity, forced expiratory volume in 1 s and peak expiratory flow rate occurred after laparoscopic cholecystectomy at each time. There were no significant changes after minor gynaecologic laparoscopy, whereas laparoscopic gynaecological surgery resulted in minor pulmonary dysfunction on the day of surgery only. We conclude that postoperative pulmonary function was less impaired after gynaecological laparoscopy than after laparoscopic cholecystectomy. This study suggests that the site of surgery is an important determinant of lung dysfunction after laparoscopy.

Abdomen↗

A global comparison of predicting equations on spirometry in the male population.

A multiple regression model considering dependent variables like vital capacity (VC), forced expiratory volume in one second (FEV1) and peak expiratory flow rate (PEFR) and age and height as independent variables for the adult male population, which includes whites of European descent and non-whites was reviewed to evaluate the role of lung function status following standardization of age and height. Non-whites showed 0.19 litre decline in VC per decade of life as compared to 0.24 litres observed in the whites of European descent. Mean VC increased 0.05 litres per centimetre in non-whites and whites. The variation in the constant term in the regression equation determined the difference between the racial groups. Like VC, FEV1 showed ethnic differences similar to those of VC. However, the magnitude of the variation in the predicted values of FEV1 was found to be less than that observed in VC. When related to VC, FEV1 showed little difference between most European populations, New Guyanaese, Indians, Negroes, Africans and Chinese because FEV1/FVC ratio had a very narrow range between 77 and 80%.

Adult↗

The value of questionnaires and spirometry in asthma surveillance programmes in the workplace.

Shipyard workers and job applicants (n = 1126) completed an asthma questionnaire, and underwent measurements of ventilatory lung function (FEV1, FEV1/FVC and PEFR) and airway responsiveness. Airway responsiveness (to inhaled methacholine) was expressed as the dose calculated to provoke a 20 per cent fall in FEV1, ie the PD20. Results were categorized into four levels: high (PD20 < 200 micrograms), medium (200-1000 micrograms), low (1001-6400 micrograms) and unquantifiable (> 6400 micrograms), which correspond with definite, possible, doubtful and no asthmatic activity. These categories agreed closely with diagnoses of asthma by general practitioners and the use of bronchodilator medication. The sensitivity and specificity of the questionnaire and the measurements of ventilatory function for detecting asthmatic activity were then determined. The questionnaire symptoms (wheeze, chest tightness, undue coughing or abnormal breathlessness) had a low (28 per cent) sensitivity for detecting definite or possible asthmatic activity and a specificity of only 73 per cent. The sensitivity of the ventilatory function tests (any one abnormal) was also low at 21 per cent with a specificity of 92 per cent. When the FEV1 < 80 per cent predicted criterion was considered separately, its sensitivity was 11 per cent and its specificity was 98 per cent. These results illustrate that caution is needed when interpreting the results of questionnaires and measurements of ventilatory lung function in the diagnosis of asthma among working populations.

Asthma↗

Selection effects of repeatability criteria applied to lung spirometry.

The potential for introducing bias in studies of pulmonary function by the exclusion of subjects with nonrepeatable measurements was examined in a cohort of Vermont granite workers followed for five years. At each annual survey, a "test failure" was defined as a test in which the two largest forced expiratory volumes in one second (FEV1) differed by more than 200 ml. "Persistent test failure" was defined in terms of 1) the number of test failures for each worker over the six surveys and 2) the difference between the two best efforts at each survey, averaged over all surveys for each worker. The rate of FEV1 loss was estimated for each subject based only on repeatable measurements. It is widespread practice to exclude subjects from analysis who do not perform repeatable lung function tests. The authors found that subjects with persistent test failure were losing FEV1 at a faster rate than subjects without. The results suggest that the application of rigid repeatability criteria may bias epidemiologic findings by the exclusion of many subjects with accelerated loss of lung function.

Adult↗