Comparison of clinical and polysomnographic characteristics of non-obese and obese patients with obstructive sleep apnea.

OBJECTIVE: To compare the clinical features, anthropometric indices, and polysomnographic data between different body mass index (BMI) subgroups of obstructive sleep apnea (OSA) patients. MATERIAL AND METHOD: The authors reviewed the data from OSA patients in Siriraj Sleep Clinic from April 2005 to September 2006. Objective measurement for sleepiness (Epworth Sleepiness Scale, ESS), anthropometric measurements [body mass index (BMI), neck circumference, thyromental distance, Mallampati S score, and occlusion pattern] and polysomnographic recordings [apnea/hypopnea index (AHI) during REM and NREM periods, respiratory arousal index, periodic leg movement index, minimal oxygen saturation, total sleep time with oxygen saturation <90%, and desaturation index] were collected. The patients were stratified into the non-obese group and obese group if their BMI was <27 or > or =27 kg/m2 respectively. RESULTS: Of the total 158 patients, 71 were non-obese and 87 were obese, no difference in mean age and sex was observed, but more patients with hypertension and coronary artery disease were noted in the obese group. Mean ESS was not different between the 2 groups. In anthropometric measurements, the obese group had statistically significant large neck circumference (41.6 +/- 3.5 cm vs. 37.0 +/- 2.9 cm, p<0.001), but the nonobese group had a shorter thyromental distance (56.4 +/- 11.7 mm vs. 61.4 +/- 11.2 mm, p=0.006), with no significant difference in Mallampatis score and occlusion pattern. In polysomnographic data, the obese group had statistical significantly more severity of various indices except for AHI during the REM period and the periodic limb movement index. CONCLUSION: Non-obese obstructive sleep apnea patients have more bony structural change than the obese ones as demonstrated by shorter thyromental distance. But degree of abnormalities during sleep was less severe in nearly all aspects.

Factors determining the severity of pulmonary function impairment in silicotic patients.

OBJECTIVE: Silicosis is the most common occupational lung disease in Thailand. Determinants of pulmonary function impairment in Thai silicotic patients have not been mentioned before. MATERIAL AND METHOD: The present study was conducted in silicotic patients who attended the Siriraj Occupational Lung Clinic in the year 2006. Patients were classified according to the forced expiratory volume in one second (FEV1) into the severe impairment group (< 50% predicted) and the non-severe group (FEV1 > 50% predicted) which includes normal FEV1. Comparison between the two groups in terms of demographic characteristics, smoking history, history of pulmonary tuberculosis, and radiographic features were assessed. RESULTS: Thirty-four patients of which 24 were female (70.6%) had an overall mean age of 53.7 years. Seven patients (20.6%) had severe impairment, four were female, three were smokers, and two had a history of pulmonary tuberculosis. All of the severe impairment patients had nodule profusion in category 2 and had large opacity. Only the presence of large opacity was significantly associated with the severity of pulmonary function impairment (p = 0.002). CONCLUSION: Only the presence of large opacity in a chest radiograph can determine the severity of pulmonary function impairment in Thai silicotic patients.

Recovery of heart rate variability in patients with moderate to severe obstructive sleep apnea after 6-month continuous positive airway pressure treatment.

OBJECTIVE: To evaluate the effect of long-term treatment with continuous positive airway pressure (CPAP) on the heart rate variability (HRV) of obstructive sleep apnea (OSA) patients. MATERIAL AND METHOD: Patients with moderate to severe OSA who had never used CPAP treatment were enrolled. Short recording HRV analysis was performed at baseline then at one, three, and six months after CPAP treatment. The measurement included low frequency HRV (LF), high frequency HRV (HF), low frequency to high frequency ratio (LHR), and standard deviation of R-R intervals (SDNN). All domains were measured both during spontaneous and deep breathing. RESULTS: There were 10 patients in the present study, all were men with the mean age of 45 years, mean body mass index 29.3 kg/m2, mean apnea-hypopnea index 60.9 events/hour, and mean average CPAP usage 4.8 hours/night. The HRV showed no significant change after one and three months of CPAP treatment. At 6 months, the only significant change was the SDNN measured after deep breathing (28.80 +/- 9.83 vs. 34.43 +/- 14.23 millisecond, p = 0.032). CONCLUSION: One aspect of heart rate variability in moderate to severe obstructive sleep apnea patients was improved after six month's continuous positive airway pressure treatment.

The cost-effectiveness of mini peak expiratory flow as a screening test for chronic obstructive pulmonary disease among the Bangkok elderly.

This study aims to explore the cost-effectiveness of Mini Peak Expiratory Flow (miniPEF) as a screening test for Chronic Obstructive Pulmonary Disease (COPD) among the elderly in 124 urban communities around Siriraj Hospital, using the gold standard of diagnosis based on the guidelines of the Thoracic Society of Thailand. There were 3,094 subjects who participated and completed all the tests. The results showed that the cut-off miniPEF percentage of predicted value of highest average accuracy was 62 per cent. The sensitivity was 72.7 per cent (95% CI 67.0-78.6) and the specificity was 81.1 per cent (95% CI 79.7-82.5) The cost of screening 19 elderly to detect one case of COPD is 923 baht, with a false negative rate of 1.9 per cent (95% CI 1.3-2.5%) and a false positive rate of 17.5 per cent (95% CI 15.4-19.6%). It is suggested that measuring a miniPEF is regarded as one of the cost-effective screening tests for COPD in the elderly.

The most cost-effective screening method for chronic obstructive pulmonary disease among the Bangkok elderly.

Our previous studies demonstrated the high prevalence and incidence of Chronic Obstructive Pulmonary Disease (COPD) among the Bangkok elderly, as well as the cost-effectiveness of a questionnaire, chest radiography, and mini peak expiratory flow rate (miniPEF) as screening tools. This final study aimed to identify the most cost-effective screening method among individual, serial and parallel combinations of the above tools, based on the guidelines for diagnosing COPD of the Thoracic Society of Thailand. There were 3,094 elderly aged 60 years and over in 124 urban communities around Siriraj Hospital who participated and completed all the tests. The results showed that the most cost-effective screening method was the miniPEF at cut-off percentage of 62 per cent of predicted value. This needed to screen 19 elderly people at a cost of 923 baht to detect one case of COPD, with a false negative rate of 1.9 per cent (95%CI 1.3-2.5), a false positive rate of 17.5 per cent (95%CI 15.4-19.6). The questionnaire is the alternative choice of screening tool.

The cost-effectiveness of a questionnaire as a screening test for chronic obstructive pulmonary disease among the Bangkok elderly.

This study aimed to explore the cost-effectiveness of using a questionnaire as a screening test for Chronic Obstructive Pulmonary Disease (COPD) among the Bangkok elderly residing around Siriraj Hospital. The gold standard used for diagnosing COPD followed the guidelines of the Thoracic Society of Thailand. The questionnaire consisted of 10 questions on smoking status, respiratory symptoms and previous history of pulmonary tuberculosis. There were 3,094 elderly who participated, completed the questionnaire, and underwent spirometry as well as chest radiography in the community. The results showed that elderly individuals who are smokers (> 0.5 pack-year) or have ever experienced sudden cough with chest oppression or dyspnea when the weather changes or who have expectorated more than two tablespoons of sputum would be suspected of having COPD with a sensitiviy of 81.4 per cent (95% CI 79.4-83.4), specificity of 62.2 per cent (95% CI 60.4-64.0) false negative rate 1.2 per cent (95% CI 0.7-1.7) and false positive rate 38 per cent (95% CI 35.3-40.7) and subsequently required spirometry and chest X-ray for definitive diagnosis. The test needed to screen 17 elderly individuals to detect one COPD case at a cost of 1,538 baht. This questionnaire is also a self-assessment tool for COPD screening among the elderly in order to encourage them to seek for early medical attention and it is recommended that this should be publicized via the mass media.

The cost-effectiveness of chest radiography as a screening test for chronic obstructive pulmonary disease among the Bangkok elderly.

Regular screening with chest radiography (CXR) in an annual physical check up of the elderly is most frequently practiced. This study aimed to identify the CXR indices and the cost-effectiveness of CXR as a screening test for Chronic Obstructive Pulmonary Disease (COPD) among the elderly in 124 urban communities of Bangkok around Siriraj Hospital. The gold standard for diagnosing COPD followed the guidelines of the Thoracic Society of Thailand. There were 3,094 subjects who participated, completed spirometry and a CXR. The selected nine indices from PA and lateral CXR for diagnosing COPD were based on the presence of hyperinflation. The positive criteria of each index were reported. The cut-off point of best average accuracy ie, Z score of the CXR was 0.07 with a sensitivity of 75.9 per cent (95% CI 70.2-81.6%), specificity of 72.4 per cent (95% CI 70.8-74.0%) and the best average accuracy of 74.1 per cent (95% CI 72.5-75.7%) whereas the cost-effective cut-off point of a Z score of CXR as a screening test for COPD was 0.04 at the lowest grand total cost. The cost to detect one case of COPD was 2,008 baht and needed to screen 17 elderly. It is suggested that CXR is probably not a suitable screening test for COPD in the elderly due to the complicated derivation of the CXR indices. However, its efficacy may be of some value in in-office diagnosis of COPD.

The prevalence and incidence of COPD among urban older persons of Bangkok Metropolis.

COPD substantially affects the national healthcare resource and healthcare cost especially among the older persons. Identifying the accurate prevalence and incidence reflects the scale of problem posed by COPD. This epidemiological study using the criteria for diagnosing COPD based on ratio of FEV1.0/FVC less than 70 per cent and the reversibility of less than 15 per cent increase of post bronchodilator FEV1.0 in the absence of parenchymal lesions and cardiomegaly in CXR (PA and lateral view) revealed the prevalence (1998) of COPD among the 3094 older persons aged 60 years and over in the communities of Bangkok Metropolis 10 km around Siriraj Hospital was 7.11 per cent (95% CI: 6.21-8.01), whereas the incidence (1999) of COPD was 3.63 per cent (95% CI: 2.83-4.43). Both the prevalence and the incidence were increased with increasing age.The disease occurred predominantly among male smokers. The distribution of mild : moderate : severe COPD in the prevalence study was 5.6:2.2:1. The current findings also suggest that tobacco smoking is the prime important cause of COPD and the indoor pollution especially cooking smoke is not significant. In particular, the unexpectedly high incidence compared with prevalence in this population probably represents the warning message to the national policy maker for prompt and effective health promotion and disease prevention to prevent further social and economic loss.

The prevalence of obstructive sleep apnea among professional hospital drivers.

Background : Several reports have suggested that about one-fifth of car accidents are sleep-related and obstructive sleep apnea (OSA) is one of the major causes of increased daytime sleepiness. Various reports from western countries have shown that different groups of drivers, especially truck drivers have a high prevalence of OSA, which may play a part in the occurrence of car accidents. Objectives : To determine the frequency of OSA and other sleep related problems in a group of professional drivers. Study design : Descriptive study. Methods : All 21 male professional drivers at one government hospital, aged between 27-57 years old, were recruited to the study. Data were collected by clinical examination, questionnaire and overnight polysomnography. OSA was defined as a Respiratory Disturbance Index (RDI) or an apnea / hypopnea index of over 5 events per hour. Results : The prevalence of OSA was 4%. Only 1 subject had severe OSA with an RDI of 102. None of them reported having car accidents but 71% reported symptoms of daytime sleepiness. Conclusion : OSA was not very common among professional drivers in this study but there were other sleep related problems reported which might relate to an increased risk of car accident. Further study of sleep disorders and their association with car accidents in a larger and broader group of drivers is needed.

Radiopathological Conference: Differences in CT findings of mediastinal lymphadenopathy between metastasis and tuberculosis not always applicable.

A case report of male patient with a right neck mass is discussed .The initial diagnosis was tuberculosis. The plain film chest and CT chest also demonstrated mediastinal lymphadenopathy. The autopsy and pathology findings indicated adenocarcinoma of lung.

Respiratory centre sensitivity and exercise tolerance in healthy Thais and in Thai COPD patients.

This study was conducted with the aim of determining the range of normal value of respiratory centre sensitivity and exercise tolerance in healthy Thais and any divergence from the normal range in those with COPD. Findings in healthy subjects disclosed that the end-tidal PCO2 and tidal volume response to CO2 were higher and exercise tolerance was lower among the elderly compared with younger subjects; only in young males was the ventilatory response to CO2 higher than in females. In the group of Thai COPD patients, all data were comparable to those of the match healthy subjects, with the exception that one-third of the patients experienced stronger ventilatory drive while breathing room air and a lower musculo-ventilation transfer index during room-air breathing as well as CO2 rebreathing.

Tuberculosis of the cervical lymph nodes.

Analysis of 188 patients with pathological diagnosis of tuberculosis or findings consistent with tuberculosis of the cervical lymph nodes during the period 1985-1988 disclosed the following pertinent findings: (1) The histo-pathological diagnoses, based on findings of chronic granuloma with or without the presence of acid-fast bacilli (AFB) on staining, were “probable tuberculosis” in 38.8 percent of the cases, and “consistent with tuberculosis” in 61.2 percent of them. It is worthy of note that proof for AFB in the 1973 report (from the same laboratory) was available only in 1.58 percent of the cases.1 (2) The supraclavicular group was the frequently diseased of the lymph nodes as found in a previous study;1 this finding also conforms to the high incidence of palpable supraclavicular lymph nodes in pulmonary tuberculosis patients.5 This persistent prevalence of the site of tuberculous involvement may be used as evidence in support of early post-primary haematogenous dissemination of the pathogenic organism, rather than the less occurring lymphogenous spread from the site of upper digestive tract infection, as recently suggested.4

Microbial florac in sputum of patients with chronic obstructive pulmonary disease.

This study was conducted to determine the variety of micro-organisms in the sputum of COPD patients, comparing those found in the stable quiescent stage with those appearing during acute exacerbation. The results showed no clear-cut differences in the distribution of either normal florae or potential pathogens in both of the diseased states. Haemophilus influenzae and pneumoniac seemed to no role in the occurence of acute exacerbation of COPD. Findings of Gram-negative bacilli in high rates, during the acute exacerbation and the quiescent states, possibly accounted for the presence of acute infection pneumonia but not the perpetuation of acute exacerbation in COPD patients.