Spirometry quality control: man versus machine

OBJECTIVE: To compare the efficacy of local quality control (QC) of BOLD (Burden of Obstructive Lung Disease) Trinidad and Tobago study with spirometer machine quality grades as well as with BOLD Pulmonary Function Reading Centre QC standards at Imperial College, London. METHODOLOGY: Quality of the randomly chosen two hundred spirometries was independently assessed by the local team based on the 2005 ATS/ERS spirometry standards. Central QC quality assessment results were blinded to the local team. However, the machine quality grades were readily available to both the central and local teams during interpretation. Local and machine QC performances were correlated with the central QC which was taken as the gold standard for this study. RESULTS: According to central QC, 17.5% of the spirometries were declared as unacceptable. The noted common errors were prolonged peak expiratory flow time(14.5%), submaximal blasts (11.5%), variable efforts (11%) and poor reproducibility (10%). Cronbach’s alpha assessment revealed an overall reliability of 0.82 and a correlation of 0.73 between central and local QC. The correlation between central and machine QC was poor(0.548). Local QC exhibited 89.1% sensitivity and 94.3% specificity relative to the central QC. Though the machine QC displayed a better sensitivity (97.6%), its specificity was significantly lower 45.7%). CONCLUSION: Local QC was effective when compared with the central QC and executed better performance than the machine’s QC. This expertise can now be utilized for the future spirometry based local research studies. Due to limitations in identifying various errors, machine QC should not solely be used as the determinant of acceptability.

Spirometric abnormalities in Jamaica children with SS and SC disease

Pulmonary complications are common in sickle cell disease. The cohort study in Jamaica is unique in seeing children with haemoglobin AA, SC and SS (control, SC disease and SS disease) regularly independent of acute illness. This allowed the controls to be used as an appropriate reference population for determining any abnormalities in spirometric measurements in children with SC and SS disease. Spirometry was performed on 50 controls, 56 children with SC disease and 77 children with SS disease. Age, height, weight, and gender were recorded for each child. Forced vital capacity (FVC), forced expiratory flow in the first second (FEV1) and forced expiratory flow from 25 percent to 75 percent (FEF 25-75) were measured. The results show that spirometric measures, FVC, FEV, and FEF are abnormal in children with SS and SC disease compared with values based on prediction equations derived from the control populations (AU)

Cigarette smoking and irreversible airways obstruction in the West Indies

Two communities, one in Jamaica and one in Guyana, have been surveyed in order to investigate the relationships between cigarette smoking and respiratory symptoms, and lung function in the West Indies. Cigarette consumption was less than that reported in the United Kingdom, particularly among women. Smoking was associated with cough, phleghm, increases in total lung capacity and residual volume, and reductions in FEV percent, transfer coeffecient (Kco), and aveolar capillary blood volume (Vc). Vital capacity (VC) and the diffusion capacity of the alveolar membranes (Dm) were normal. After allowing for differences in age and tobacco consumption, less cough, phleghm and airways obstruction occurred in the West Indies than has been reported in the United Kingdom. Forty-seven patients in Jamaica with chronic obstructive lung disease were followed for three years. All except six female asthmatics were either current smokers or ex-smokers. Smoking in patients was associated with a similiar but more severe pattern of lung disease to that found in survey subjects with, in addition, reductions in VC, and Dm. In the non-smoking asthmatics Kco, Dm, and Vc were normal. The lung function of these 47 patients was similiar to that reported for UK patients even though both chronic bronchitis and hypercapnia were considerably less common in Jamaica. Emphysema was present in all six patients who died and came to necropsy. It is suggested that in the West Indies emphysema contributes more than bronchitis to airways obstruction in smokers. There was also evidence that subjects of African origin were less susceptible to the emphysema-producing effect of cigarettes than were other ethnic groups (AU)

The lipoid pneumonia of blackfat tobacco smokers in Guyana

In Guyana, a large number of patients have been diagnosed as having a diffuse pulmonary fibrosis of unknown aetiology, characterized by typical radiological appearances, dyspnoea, cough, weight loss, and eventually pulmonary heart disease. Investigation of 56 patients showed that all had smoked a tobaco known as 'blackfat' or 'black tobacco'. In a community survey 20.4 per cent of the population aged 55 years and over smoked this tobbaco. 19.6 per cent of the blackfat smokers but no non-blackfat smokers showed definite radiological evidence of pulmonary fibrosis. Smokers with, but not those without fibrosis, had severe airway obstruction. Immunological studies made it unlikely that an extrinsic allergic aveolitis had caused the radiological changes. Three post-mortem open-lung specimens were obtained and in each case the histology showed a diffuse interstitial fibrosis and vasculitis associated with large deposits of lipid surrounded by black amorphous material. Blackfat is a tobacco leaf to which mineral oil and vaseline is added for flavouring and as humectants. The presence of oil in the tobacco, and the post-mortem findings of oil in the lungs, indicate that the diffuse pulmonary fibrosis can be more accurately described as a lipoid pneumonia caused by the inhalation of mineral oils when blackfat is smoked. The potential health hazards of many tobacco additives, particularly oils, employed by the tobacco industry should be recognized. A similar type of disease as that found in Guyana may be present in other parts of the world where blackfat, or related tobacco, are smoked.(Summary)

A community survey of respiratory disease among East Indian and African adults in Guyana

The belief that chronic bronchitis is more prevalent among Indians than Africans in the Caribbean area was investigated by a community survey in Guyana. Respiratory symptoms were assessed by a standard questionnaire, ventilatory capacities were measured, and chest radiographs were taken of some 800 African and Indian men and women aged 35 to 54 years living in adjacent and similar communities. Histories of morning cough, chronic cough, morning phlegm, and chronic phlegm (chronic bronchitis) were more common in Indians than Africans. Although these respiratory symptoms were much more common in smokers than non-smokers, the higher prevalence rates in Indians could not be explained by smoking habits which were similar in the two races. Chronic bronchitis occurred in 17.3 percent of Indian and 2.4 percent of African male smokers and in 6.1 percent and 2.2 percent of Indian and African female non-smokers respectively. Judging by the history, lung infection, and clinical signs, chronic bronchitis was more severe in Indians than Africans. The condition was more common among field labourers on sugar estates but, although the majority of field labourers were Indian, this occupational difference only partially explained the difference in prevalence between Indians and Africans. Indians, for reasons unknown, appear to have a greater susceptibility than Africans to chronic bronchitis.(AU)

Bagassosis: an epidemiological, environmental, and clinical survey

An epidemiological and environmental survey of 170 bagasse workers employed by a raw sugar producing company in Trinidad was carried out in order to assess the prevalence of respiratory symptoms and to determine if exposure to bagasse was associated with alterations in ventilatory capacity. The epidemiological survey failed to reveal a significantly increased prevalence of respiratory symptoms in the more exposed group but showed that the group of Indian workers who were regularly and continously exposed to bagasse had a significantly lower ventilatory capacity than the control group. This diminished ventilatory capacity was demonstrated despite negligible dust concentrations in the plant. However, the possibility that persistence exposure to low concentrations of bagasse may be the cause must be considered. During a five-year period, 17 patients with bagassosis were seen, the clinical picture being similar to that described in extrinsic allergic alveolitis from other causes. The systematic variations demonstrated in some indices of ventilatory function in different racial groups is discussed.(AU)