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Background: Tuberculosis is one of the biggest public health concerns in India with a prevalence of 195 cases per 100000. Silica is cytotoxic to macrophage which is primary defense mechanism to tubercular bacilli and, hence, exposure to silica dust increases risk for TB. Silica exposed persons are at 2.8 to 39 times greater risk of affected by pulmonary tuberculosis in comparison to healthy subjects. Methodology: A cross-sectional epidemiological study was conducted among 935 workers in sandstone mining. Full-size posteroanterior view (PA) chest X-ray in full inspiration was evaluated and evidence of tuberculosis was noted. Fourier transform infrared spectrophotometer was used for determining the free silica in 23 dust samples. Results: 6.4% X-rays showed evidence of TB and silica dust concentration was 0.11 to 0.16 mg/m3. The TB cases significantly increased from 2% to 6% to 12.7% as the work exposure increased from 20 years respectively. 8.5% of the TB cases were seen among the workers having more than 10 years of work exposure. The odds ratio (95% CI) for work exposure more than 10 years to less than 10 years was 4.53 (1.92–10.65). Conclusion: Reduction of silica particles from work environment can significantly reduce the number of TB cases and hence wet drilling should be practiced and personal protective equipment should be regularly used.

The aim of this study was to evaluate the ability of experienced thoracic radiologists to assess full inspiration based on two CT slices, one above and one below the carina, in normal subjects. Ten healthy volunteers were studied. Total lung capacity (TLC) was measured with a body plethysmograph. High-resolution computed tomography (HRCT) was performed in two slices at TLC and at various expired volumes. Mean Hounsfield values (HU) were calculated. Unidentifiable images, stored on a web server, were analysed visually by experienced thoracic radiologists. The results show that the mean lung density at TLC varied by approximately 40 HU between individuals. Within an individual this may correspond to a decrease in lung volume of approximately 25% of TLC. On visual determination of images taken at 65-74% of TLC, more than one-third of the images were assessed as taken at full inspiration; of the images taken at 75-84% of TLC, approximately 50% were assessed as taken at full inspiration. We conclude that visual determination of full inspiration on CT images in normal subjects is highly inaccurate. If quantitative density measurements are to be used in the diagnosis or follow-up of lung disease, thorough control of full inspiration is recommended.

SHANDLING, A.H., ET AL.: Physical Determinants of the Endocardial P Wave. Reliable atrial sensing of intrinsic P wave activity is important to ensure optimal atrial or dual chamber pacemaker function. Various physical factors (e.g., posture, respiration, exercise) may influence P wave characteristics and impair adequate sensing. To investigate this phenomenon, we measured the average of three P wave amplitudes (PWA) and calculated slew rates from telemetered printouts acquired from Pacesetter pacemakers in 32 patients. These measurements were performed in various body positions, with upright exercise and in varying stages of respiration. Results: the mean supine PWA increased on full inspiration (3.56 ± 1.3 mV versus 3.25 ± 1.2 mV during quiet respiration, p < 0.001), and also increased significantly with full expiration. The mean PWA increased on assuming the erect position (3.25 ± 1.2 mV increasing to 3.49 ± 2.3 mV, p < 0.001); in the upright position, the mean erect PWA during quiet respiration was not significantly influenced by the stage of respiration. The mean upright exercise PWA did not differ significantly from the preexercise erect PWA (3.50 f 1.2 with exercise, and 3.47 ± 1.5 before exercise; P = NS). Calculated slew rates were not different lying versus standing. Conclusions: the mean supine PWA increases significantly at the extremes of respiration and on assuming the erect body position; upright exercise results in no appreciable change in the erect PWA. Atrial sensitivity adjustments based on standard supine testing should be adequate for all body positions. (PACE, Vol. 13, December, Part I 1990)

This report is based upon a personal series of nearly 200 investigations, conducted between 1962 and 1966, in which an attempt was made to widen the range and increase the accuracy of information obtainable from translateral films. It was found that the tradition of taking abdominal films only in expiration ought to be abandoned in translateral films. Films taken in full inspiration may be the only ones in which a significant measurement of the retro-gastric mid-plane diameter can be made and in which a pancreatic impression appears upon the posterior gastric wall. The view is also expressed that on the translateral film the shape and size of the tunnel visible between the gastric fundus and the duodenojejunal flexure provides a basis for the estimation of the shape and size of the body of the pancreas. It is also possible to gauge the thickness of the mesocolon and of the retroperitoneal fatty layers in most cases. By this means, suitable corrections can be made to measurements on the translateral radiographs.

It is widely accepted that a palpable spleen in the adult population is always enlarged and pathological. The aim of this study was to assess the validity of this statement. As a routine, our protocol for liver-spleen studies includes liver pliability, which demonstrates the level of the hemidiaphragms at full inspiration and expiration, as well as splenic size and colloidal uptake. Sixteen hundred 99mTc sulphur colloid liver-spleen studies, which had been performed in our Department, were reviewed. In 21 patients, who had been referred with "splenomegaly for investigation", the scintigraphic splenic size was 13 cm posterior length or less. In this group, splenic palpability was confirmed by at least two clinicians. Follow-up did not reveal any evidence of splenic disease in 18 of the 21 patients. In a separate postmortem follow-up of 123 sequential liver-spleen scans, 100 patients were noted to have a scintigraphic splenic size of 13 cm posterior length or less. This was shown to be a reliable upper limit of normal because 98% of spleens in this group weighed 250 g or less and were normal at post-mortem examination. This study demonstrates that a palpable spleen is not necessarily enlarged or pathological.

Posteroanterior and lateral radiographs of the lungs of 30 normal adults were obtained at total lung capacity (TLC) and 1 sec after initiation of forced expiration from ttlc. simultaneous spirographic recording of the volume expired (FEV-1) and independent plethysmographic recording of TLC were obtained. Two types of measurements were made from the radiographs: 1) surface areas of the lung fields, measured planimetrically; and 2) combinations of linear distances between selected points. These radiographic measurements and the measured lung volumes were subjected to computer analysis to develop reliable formulas for determining lung volumes solely from radiographs. Formulas derived using planimetry produced multiple correlation coefficients of 0.95 for TLC and 0.89 for volume during forced expiration. Use of linear measurements produced multiple correlation coefficients of 0.92 for TLC and 0.84 for dynamic volume. Thus, in normal subjects, static lung volumes and lung volumes during dynamic forced expiration can be determined from radiographs.

THE FORCED expiratory volume (F.E.V.), or volume of air expired during a forced expiration from full inspiration in usually 0.75 or 1 second, is widely accepted as a useful measure of ventilatory capacity. Two types of apparatus are in common use for its measurement. The recording spirometer with the fast-moving kymograph has the advantage of providing a permanent record which can later be analysed in various ways.1, 2The simple spirometer with electronic timer described originally by Gaensler3and modified by McKerrow et al.4shows the volume of air expired in a preset time period by a pointer indicating on a scale on the spirometer wheel. The advantages of this type of machine are its greater portability, ease of use, and the provision of the reading immediately without the necessity of analysing a record—features which make it especially valuable for routine clinical use and in field

To the Editor: —Permit me to vouchsafe a bit of valuable information for the benefit of your readers in regard to Kuhn's aspiration mask. It may not be generally known that all the beneficial results of the mask can be secured in a much simpler manner by using a section of a small catheter, about No. 16F, or a straw or quill to draw the breath through, thus retarding inhalation quite as effectually as by use of the cumbersome mask; but such is the case. The only benefit of the mask is to insure a deep, full inspiration of air slowly and gradually, holding it a few seconds and then its sudden expiration, which, as you remark (The Journal, Feb. 22, 1913, p. 632), produces negative compression of the lungs, sucking the blood from the right chamber of the heart into the lungs. When the heart is weakened and tired

These three cases of non-opaque foreign body inhalation in children are reported as a reminder that a chest film taken in full inspiration may be misleading, and to demonstrate the necessity of screening these cases with exposure of films in both inspiration and expiration in order that a non-opaque foreign body in a bronchus may be diagnosed and localised.