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PubMed1976

The relationship between symptoms and functional abnormalities in clinically healthy cigarette smokers.

Because a number of "early tests" may now be used to measure abnormalities of lung function in cigarette smokers with normal airflow rates, we evaluated the symptoms of cough, sputum, wheezing, and shortness of breath in 60 nonsmokers and 49 smokers to determine whether these symptoms correlated with measurements of lung function that are believed to be altered by mild obstruction. One or more symptoms were present in 5 per cent of the nonsmokers and 90 per cent of the smokers. Individual symptoms, sums of symptoms (symptoms score), and various combinations of symptoms correlated poorly or not at all to measured values for dynamic lung compliance, closing volume, closing capacity, slope of Phase III, and helium flow-volume curves. The symptoms score correlated negatively (P less than 0.05) with forced maximal expiratory flow at 50 per cent of vital capacity. Inasmuch as the serious consequences of chronic airway obstruction are related to abnormalities of lung function, it is likely the function tests will prove more useful than symptoms to reveal smokers at risk to develop chronic obstructive pulmonary disease. Symptoms cannot be used to detect smokers who are liable to have functional abnormalities suggestive of mild peripheral airway obstruction.

Adult↗
PubMed1976

Protective effect of disodium cromoglycate against airway constriction induced by hemp dust extract.

The effect of disodium cromoglycate (DSCG) was studied in 14 healthy subjects following hemp dust extract (HDE) inhalation (10-min exposure). Ten subjects were given 20 mg of DSCG or a placebo and then challenged with dust aerosol at 30 min post-DSCG inhalation. Partial expiratory flow-volume (PEFV) curves were recorded at least 30 min after exposure, and maximum expiratory flow rates at 40% of the control vital capacity [MEF40%(P)] were read from these curves. Significant acute reduction in MEF40%(P) were recorded after HDE alone and after pretreatment with placebo (p less than 0.01). There was considerable protection from a single dose of 20 mg of DSCG against hemp-induced bronchoconstriction although the acute reductions in MEF40%(P) were still statistically significant at 20 and 30 men postexposure. A group of 7 subjects was given 40 mg of DSCG or placebo 30 min prior to HDE inhalation. In another experiment this group was given 20 mg of DSCG four times daily for 2 days, and on the third day challenged with HDE. The protective effect of DSCG is a short-term one: somewhat less protection was seen after 2 days of four times 20 mg of DSCG/day than 30 min after a single dose of 40 mg. Measurement of airway conductance (Gaw) in 6 subjects demonstrated prevention of acute reductions in Gaw at low lung volumes (25% VC) in 4 out of 6 subjects. We suggest that inhalation of 40 mg of DSCG prior to a work shift might be considered as a temporary means of protecting textile workers against the constrictor effects of dust in their work.

Adult↗
PubMed1977

Relationship of lung recoil to lung volume and maximum expiratory flow in normal children.

Thirty-one normal children, aged 6--18 yr, were studied by measurements of static lung volumes, static expiratory pressure-volume (PV) curves, and maximum expiratory flow-volume (MEFV) curves. A theoretical standard volume was used to compare children of differing size and this showed that total lung capacity (TLC) is also a valid standard volume. The shape of the PV curve was found to change so that static elastic recoil at a fixed proportion of TLC was higher in older than in younger children. This was also true of static recoil at functional residual capacity (FRC) and an associated increase in the ratio of FRC to TLC was interpreted as evidence for increase in outward recoil of the chest wall during childhood. Since static recoil at "closing capacity" (CC) remained constant, a decrease in the ratio of CC to TLC was quantitatively explained by the PV shift during childhood. Although maximum expiratory flow at various lung volumes increased in constant proportion to TLC, "upstream conductance" decreased relative to TLC. It was concluded that maturation of the respiratory system is disproportionate in several features during childhood and that these disproportions are likely to be even more prominent during infancy and early childhood.

Adolescent↗
PubMed1978

Maximum expiratory flow and transpulmonary pressure in the hamster.

Maximum expiratory flow was measured in 19 normal, anesthetized, tracheostomized, supine hamsters from records of forced deflation produced by the application of varying degrees of negative pressure to the tracheostomies of animals whose lungs had been previously inflated to a transpulmonary pressure (PL) of 25 cmH2O. Flow was measured with a pneumotachograph, volume with a constant-volume pressure plethysmograph and pleural surface pressure (Ppl) with a water-filled esophageal catheter. The esophageal pressure measurement overestimated Ppl and a simple technique was based on an estimate of the resting volume of the chest wall. This volume, at which the Ppl is zero, was calculated for anesthetized supine hamsters from the measurement of respiratory-system pressure and PL made independently of esophageal pressure and was found to be about 30% of vital capacity (VC). Flow limitation was present below 70% of VC with a tracheal deflation pressure of -30cmH2O. Negative effort dependence of flow was seen in small segments of the flow-volume curves. Mean +/- SD maximum expiratory flow at 50% VC was 52 +/- 9.5 ml/s or 9.1 VC/s. Upstream resistance was 0.09 +/- 0.03 cmH2O/ml per s.

Airway Resistance↗
PubMed1978

Indications for pulmonary function testing.

Pulmonary function testing is needed to determine the pathophysiology present in the patient with cardiopulmonary disease. Blood gases and pH should be obtained during emergency situations and during cranial, thoracic, and extensive cervical or abdominal surgery. Lung function tests can be divided in global such as spirometry and diffusing capacity which study the ventilation and transfer of gases and regional determinations of ventilation and perfusion. Both types of tests complement each other and should be used together. The spirometry should consist at least of determination of the vital capacity and is determined in the first second to ascertain if there is obstructive lung disease. Some tests such as flow-volume curves, alveolar-arterial gradients and closing volume are very useful to detect early pulmonary disease before any symptoms or findings are present. This is probably one of the most important medical indications for pulmonary function testing. Before certain types of surgery pulmonary function testing is indicated; if the spirometry and diffusing capacity tests are normal, there is no pulmonary contraindication for the planned surgery. In chest surgery if there is significant compromise of the spirometry and diffusing capacity regional lung function tests are indicated to study the pathophysiology at regional level, thus trying to circumscribe the lung resection to the diseased areas.

Blood Gas Analysis↗
PubMed1977

Maximal expiratory flows at functional residual capacity: a test of lung function for young children.

Maximal expiratory flows at functional residual capacity were measured noninvasively from partial expiratory flow-volume curves in 65 awake, healthy children, 4 to 6 years of age. The variabilities within and between subjects were nearly identical to those reported for flows low in the vital capacity obtained from older subjects. This test of maximal expiratory flow at functional residual capacity has the advantage that the subject does not have to inspire to total lung capacity, exhale to residual volume, or make a maximal effort, and it is therefore applicable to the testing of young children who cannot perform a vital capacity maneuver. Measurement of this flow rate in 20 patients of the same age with lung disorders of varying severity revealed abnormal flow rates in more than 50 per cent of patients. Functional residual capacity was measured by the closed-circuit helium-equilibration method. When flow rates in liters per sec were compensated for lung size, girls had significantly larger flow rates than did boys. This suggests that the lungs of young children may grow differently according to genetic determinants related to sex.

Adolescent↗
PubMed1979

Correlation between the function and structure of the lung in smokers.

To study the relationship between morphologic changes and alteration of lung function, the excised lobes of 21 smokers and one nonsmoker who required lobectomy for small peripheral tumors were inflated and fixed in formalin, and measurements of bronchiolar narrowing and degree of emphysema were made. All patients had comprehensive pulmonary function tests (including diffusing characteristics, the single-breath N2 test, measurements of elastic recoil, and flow-volume measurements with air and helium) performed before lobectomy. Eight of the lobes excised from the smokers had emphysema of grade 15 or more, the greatest being grade 50. Lobes from 11 patients had evidence of airway narrowing. There were 6 lobes with both emphysema and airway narrowing. Pulmonary function was abnormal in some aspect in all lobes except that from the nonsmoker. Whereas the tests of diffusing capacity, particularly the fractional uptake of CO, correlated with the degree of emphysema, the tests of elastic recoil were not predictive of this early degree of emphysema. The degree of small-airway narrowing correlated with maximal mid-expiratory flow rate and the single-breath N2 test. The maximal flow/static recoil pressure curves were the most sensitive indicators of airway abnormality in the patients with emphysema.

Aged↗
PubMedDate not supplied

[Technical and experimental study of two electronic spirometers (author's transl)].

Two electronic spirometers which use standard pneumotachographs were evaluated for their static and dynamic response, and clinically compared in 20 subjects to a reference flow channel. In the Pneumoscreen the data are digitalized and stored, permitting to play back the flow-volume curves at low or high speed. The instrument provides a direct read-out of forced vital capacity and of five indexes of forced expiration. It was found perfectly adequate with respect to linearity and frequency response. However, due to some systematic error in digital processing, maximum flow at low lung volumes appeared substantially over-estimated. Besides forced vital capacity and a number of indexes of forced expiration, the Medistor type M 010 may be used to measure ventilation, tidal volume, frequency and maximum breathing capacity. The data are processed by an analog computer. The transducer was found poorly linear with inadequate frequency response. However, no systematic bias in the measurements was found, except for peak flow and maximum breathing capacity.

Airway Obstruction↗
PubMedDate not supplied

Tests of minimal obstruction in the small airways: interrelationships and physiologic significance.

Several technics have become popular to detect airway obstruction in the small (less than 2 mm diameter) peripheral bronchi which appear to be the site of the early lesions in chronic obstructive pulmonary disease (COPD). These include determining maximal midexpiratory flow rate (MMFR) from the expiration spirogram, maximum expiratory flows at low lung volumes from the maximum expiratory flow-volume (MEFV) curve, a comparison of flow-volume curves during air and helium/O2 breathing, demonstration of frequency dependence of compliance, and the measurement of closing volume (CV). This discussion attempts to interpret the literature relative to these tests, examining their physiologic basis and clinical significance while relating them to the standard spirometric tests. The aim is to provide the clinical anesthesiologist with a better understanding of the information they provide, since their physiologic basis relates well to the many aspects of abnormal lung function which appear during anesthesia and the entire perioperative period.

Airway Obstruction↗
PubMed1979

Peripheral airways obstruction in patients with rhinitis.

Nine young lifetime nonsmoking patients with symptoms of rhinitis but without any history of asthma or wheezing and nine age-matched healthy lifetime nonsmoking control subjects were studied with respect to subdivisions of lung volume, forced vital capacity, forced expiratory volume (1.0 sec), and flow-volume curves breathing air, and also breathing a mixture of 80% helium--20% oxygen (He-O2) from which were obtained airflows at 50% VC (Vmax50), the percentage increase in Vmax50 breathing He-O2 as compared to air (deltaVmax50) and the point where He-O2 and airflow-volume curves became identical (Visov). No significant differences between the two groups in age, subdivisions of lung volume or forced expiratory airflow rates were recorded. However, deltaVmax50 was significantly lower in the patients (16.4 +/- 12.0) compared to the controls (47.7 +/- 16.4) (p less than .001) and Visov was higher in the patients (28.4 +/- 14.9) as compared to the controls (14.4 +/- 7.6) (p less than .01). After bronchodilator therapy Vmax50 increased in the control subjects (p less than .005) but not in the patients and deltaVmax 50 decreased in the control group but was unchanged in the rhinitis patients. These results suggest that patients with rhinitis who have normal airflow rates may have peripheral airways obstruction not readily reversible with bronchodilators.

Adult↗