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Biomedical subjects

W C Tan

Publications and source records attributed to W C Tan.

At least 73 records · Page 4Linked to original sources
PubMed1994

Surgical resections in parous patients with distal ileal and colonic Crohn's disease.

The surgical resection rates among parous women with distal ileal and colonic Crohn's disease have been compared with resection rates among distal ileal (n = 197) and colonic (n = 332) Crohn's disease patients. Thirty of 44 parous women with distal ileal Crohn's disease and 28 of 44 with colonic Crohn's disease had achieved their first pregnancy on average 8 years and 6.2 years respectively before the diagnosis of Crohn's disease was established. Resections for each patient were negatively correlated with parity in both groups. (Distal ileal disease (p = 0.034, rs = 0.3207), colonic disease (p = 0.051, rs = -0.2960)). Patients with distal ileal Crohn's disease and a history of pregnancy at diagnosis (n = 30, mean follow up = 15 years) had fewer resections/patient when compared with the published resection group: mean (SD); 1.17 (0.65) v 1.57 (1.05), p = 0.006. Patients with colonic Crohn's disease and a history of pregnancy at diagnosis (n = 28, mean follow up = 16.5 years) had fewer resections/patient when compared with the published resection group: mean (SD); 0.68 (0.77) v 1.05 (0.77), p = 0.019. In summary, patients with distal ileal and colonic Crohn's disease, who had been pregnant in the past subsequently need fewer surgical resections. Pregnancy could influence the natural history of Crohn's disease either by decreasing immune responsiveness or by retarding fibrous stricture formation, which is the commonest indication for surgical intervention.

Adolescent↗
PubMed1994

Prevalence of asthma and risk factors among Chinese, Malay, and Indian adults in Singapore.

BACKGROUND: The prevalence and morbidity of asthma vary greatly among different ethnic communities and geographical locations, but the roles of environmental and genetic factors are not fully understood. The differences in prevalence of adult asthma among Chinese, Malay, and Indian ethnic groups in Singapore were examined, and the extent to which these could be explained by personal and environmental factors were investigated. METHODS: A stratified disproportionate random sample (n = 2868) of Chinese (n = 1018), Malays (n = 967), and Indians (n = 883) of both sexes was drawn from households in five public housing estates, and an interviewer administered questionnaire was used to determine cumulative and current prevalence of "physician diagnosed asthma" (symptoms with a physician diagnosis of asthma). RESULTS: Lifetime cumulative prevalence (standardised to the general population) of "physician diagnosed asthma" was 4.7% in men and 4.3% in women; 12 month period prevalences were 2.4% and 2.0%, respectively. Cumulative prevalence of asthma was significantly higher in Indians (6.6%) and Malays (6.0%) than in Chinese (3.0%); period prevalences of asthma were 4.5% in Indians, 3.3% in Malays, and 0.9% in Chinese. Ownership of cats or dogs was more frequent in Malays (15.4%) and Indians (11.2%) than in Chinese (8.8%). Rugs and carpets were also more frequently used by Malays (52.2%) and Indians (40.7%) than by Chinese (8.9%). Current smoking prevalences were higher in Malays (27.3%) than in Indians (19.4%) and Chinese (23.0%). Malays and Indians did not have higher rates of atopy (11.1% and 15.2%, respectively) than Chinese (15.4%). Adjustment for these factors in multivariate analyses reduced the greater odds of asthma in Malays and Indians, but not to a significant extent. CONCLUSIONS: There are ethnic differences in the prevalence of asthma in Singapore which are not entirely explained by differences in smoking, atopy, or other risk factors. Other unmeasured environmental factors or genetic influences are likely to account for residual differences in the prevalence of asthma.

Adult↗
PubMed1994

Rapid shallow breathing (frequency-tidal volume ratio) did not predict extubation outcome.

This was a prospective study of 52 patients that were extubated in our medical intensive care unit. Rapid shallow breathing, represented by a ratio of frequency to tidal volume (f/VT) of more than 105, was evaluated either on continuous positive airway pressure or pressure support prior to extubation as a marker of extubation outcome. Twelve out of 13 patients (92 percent) with rapid shallow breathing (f/VT ratio > 105) were successfully extubated. Out of 9 extubation failures only 1 patient had a f/VT ratio more than 105 (11 percent). A measured f/VT ratio of less than 105 had a sensitivity and specificity of 72 and 11 percent, respectively, for extubation success. Patients who had unsuccessful outcomes were ventilated for a significantly more prolonged period (9.6 +/- 6.8 d vs 4.6 +/- 3.9 d, unpaired t test, p = 0.004). We conclude that the presence of rapid shallow breathing during a weaning trial with the patient on partial ventilatory support does not necessarily preclude successful extubation.

Adolescent↗
PubMed1994

Fatal haemoptysis in Salmonella typhimurium septicaemia--a cautionary tale.

Septicaemia and mycotic aneurysm may occur in a patient who is an enteric-carrier of Salmonella typhimurium. We report such a case of an elderly man who presented with chest pain and fatal massive haemoptysis from a likely mycotic thoracic aneurysm. This report underscores the importance of increased awareness of the disease which may allow more frequent and earlier diagnosis.

Aged↗
PubMed1994

Epidemiology of chronic (perennial) rhinitis in Singapore: prevalence estimates, demographic variation and clinical allergic presentation.

We conducted a population-based study involving a stratified cluster disproportionate random sample of 2868 adults aged 20 to 74 years selected from five housing estates (Yishun, Toa Payoh, Jurong East, Geylang/Eunos and Bukit Merah). Chronic rhinitis was defined as the usual presence of symptoms of blocked or running nose, apart from colds or the flu, lasting for more than a year. Allergic rhinitis was considered to be present if these symptoms were associated with conjunctivitis or recognisable provocation by commonly known allergens, namely house dust, dogs, cats, birds, pollen, or medicines. The estimated general population prevalence of chronic rhinitis was 10.8% (95% confidence interval (CI) 8.8-12.7). Higher prevalences were noted in males, in younger adults, in Indians and Chinese, in those with higher socio-economic status, and in Toa Payoh, Jurong East and Geylang/Eunos. The prevalence of allergic rhinitis was 5.5% (95% CI 4.5-6.5). The most common 'allergenic' factor in allergic rhinitis was house dust (73%); provocation by birds, cats or dogs (5%), grass or tree pollens (5%), and medicine (5%) was less common but likely to have been under-recognised. Provocation by change in temperature (54%) and early in the morning (64%) was equally frequent in both 'allergic' and 'non-allergic' rhinitis; cigarette smoke, petrol and diesel fumes, food and work environment were less common (4-12%). Allergic rhinitis was highly significantly associated with asthma (13.9% in allergic rhinitis, 4.4% in non-allergic rhinitis, and 2.2% in non-rhinitic subjects).

Adult↗
PubMed1993

Nonfatal and fatal infections caused by Chromobacterium violaceum.

Human infection caused by Chromobacterium violaceum is rare, but when it occurs it is associated with a high mortality rate. We report the cases of two patients with infection due to Chromobacterium violaceum. One patient presented early in the course of disease and survived after receiving appropriate antibiotic therapy. The other patient presented late in the course of disease and died of fulminant sepsis with abscesses in multiple organs. We discuss the similarity between C. violaceum infection and the septicemic form of melioidosis.

Adult↗
PubMed1993

Diffuse jejunoileitis of Crohn's disease.

Diffuse jejunoileitis is an uncommon, but important manifestation of Crohn's disease because of the associated high morbidity and challenges in medical management. Despite this there have been no studies of prognosis or management of diffuse jejunoileitis for nearly 20 years. This study analysed the outcome among 34 patients (20 women and 14 men) with diffuse jejunoileitis diagnosed between 1960 and 1991 including clinical features, medical and surgical management, death rates, current status, and prognosis. Diffuse jejunoileitis presents in younger patients (mean age at diagnosis 26.4 years) than those with distal ileal Crohn's disease (mean age at diagnosis 33.3 years). Nearly all presented with clear cut abdominal symptoms including a combination of colicky abdominal pain (91%), weight loss (62%), and diarrhoea (53%). Most patients had severe symptoms reflected by the fact that 77% had been treated with corticosteroids for periods of more than six months at some stage during their follow up. The mean follow up from diagnosis was 16 years. Twenty eight patients (82%) had at least one operation for diffuse jejunoileitis and two thirds of the patients (n = 21) required two or more operations. The frequency of surgical intervention was particularly high in the younger patients (r = 0.71, p < 0.001). The proportion of patients requiring surgery was highest in the first year after diagnosis. The annual operative rate was 15% for the first 10 years and then it fell to 5.2% in years 11-15, and 2.6% in years 16-20. The data suggest that the disease does burn itself out over time. The increasing use of strictureplasty for short strictures and the minimal use of resection has eliminated problems associated with the short small bowel syndrome. The longterm prognosis of this patients is good. Only two patients died (one of perforation of the jejunum and another of an unrelated bronchogenic carcinoma). After a mean interval from diagnosis of 16 year, 24 of 32 living patients are well and symptom free. Only eight have abdominal symptoms of whom three are receiving corticosteroid treatment and one azathioprine. The combination of anti-inflammatory drugs with the relief of recurrent obstructive symptoms by strictureplasty can together produce a good longterm prognosis in most patients with diffuse jejunoileitis.

Adolescent↗
PubMed1993

Respiratory symptoms and lung function effects of domestic exposure to tobacco smoke and cooking by gas in non-smoking women in Singapore.

STUDY OBJECTIVES: To investigate the effects of passive exposure to tobacco smoke and gas cooking at home on respiratory symptoms and lung function of non-smoking women. SETTING: Evidence on the effects of passive smoking and exposure to nitrogen dioxide from gas cooking on the respiratory health of adults is limited and variable. Over 97% of women in Singapore do not smoke, and a principal source of indoor air pollution for housewives is passive smoking and gas cooking. DESIGN: This was a cross sectional (prevalence) study of a population based sample of 2868 adults aged 20 to 74 years in Singapore. A structured questionnaire administered by trained interviewers was used to collect data on passive smoking, gas cooking, respiratory symptoms, and other relevant variables. Passive smoking was defined as exposure to cigarette smoke from one or more members of the household who had ever smoked. Gas cooking was defined in terms of the weekly frequency of gas cooking, as well as the frequency with which the respondent's kitchen was filled with heavy cooking fumes (rarely, occasionally, often). Forced expiratory volume in one second (FEV1) was measured by using a portable Micro-spirometer. Multivariate analyses were used to estimate relative odds of association for respiratory symptoms and FEV1 effect, with adjustment for potential confounding variables. PARTICIPANTS: Of a total of 1438 women in the sample, 1282 women who had never smoked provided questionnaire data and 1008 women provided acceptable readings of FEV1 for analysis. MAIN RESULTS: Passive smoking was significantly associated with greater relative odds of usual or chronic cough and phlegm, wheezing, and breathlessness on exertion, as well as lower FEV1. Greater relative odds of respiratory symptoms were also associated with the weekly frequency of gas cooking, although these results were statistically insignificant. Chronic cough and phlegm and breathlessness on exertion, however, were significantly associated with the frequency with which the kitchen was filled with heavy cooking fumes. A lower FEV1 was found in women who cooked frequently (more than thrice a week). CONCLUSION: Domestic exposure to cigarette smoke and gas cooking is associated with increased risks of respiratory symptoms and impairment of lung function in non-smoking women in Singapore.

Adult↗
PubMed1993

Factors influencing pulse oximetry as compared to functional arterial saturation in multi-ethnic Singapore.

Noninvasive oximetry provides continuous monitoring of arterial oxygen saturation and hence, early detection of hypoxia. This has proved to be a useful adjunct to patients' safety, and is considered indispensable in certain settings. However, errors may be present in the pulse oximeter estimation (SpO2) of arterial oxygen saturation (SaO2), which may be due to various parameters. We have studied a multi-ethnic population where the skin pigmentation is different, and also under different conditions comparing SpO2 with SaO2. Our results showed that SpO2 estimation of SaO2 amongst the three racial groups (Chinese, Malays, and Indians) varied significantly (ANOVA, p < 0.05). The over-estimation was more pronounced by hypoxic conditions and jaundice. Haemoglobin and systolic blood pressure did not affect the difference between SpO2 and SaO2.

Adult↗
PubMed1993

Acute physiology and chronic health evaluation (APACHE II) scoring in the Medical Intensive Care Unit, National University Hospital, Singapore.

The intensive care unit provides multisystem support and therapy to critically ill patients, and represents an expensive part of hospital medicine. This survey validates the use of APACHE II as a severity scoring system that allows reliable prediction of outcome of intensive care patients in Singapore. The mortality rate of 37.4% in our medical intensive care unit compares favourably with the other established intensive care units in the United States of America. Our results also indicate that the aged fared as well as their younger counterparts. Patients with sepsis fared poorer than expected from their APACHE II scores, and stroke patients needing intensive care admission had an extremely poor prognosis (mortality rate of 85.7%). High APACHE II scores are associated with invasive haemodynamic monitoring.

Adolescent↗
PubMed1993

Thrombocytopenia in sepsis: a predictor of mortality in the intensive care unit.

Disseminated intravascular coagulation (DIC) and thrombocytopenia are well-known complications of sepsis, but the relationship between these coagulation abnormalities and outcome have not been well documented. We studied the incidence of thrombocytopenia and DIC in our Medical Intensive Care Unit, and evaluated their usefulness as prognostic risk factors for mortality. Platelet count was not found to be an independent risk factor associated with overall mortality in the 107 patients studied. In the sub-group of 53 patients with sepsis, 22 (42%) developed DIC, 31 (58%) developed thrombocytopenia (< 150,000 x 10(9)/L) and 27 (51%) died. Thrombocytopenia was associated with presence of DIC (p = 0.003), but not with the type of infecting organism. The platelet count in non-survivors (mean +/- sem, 97 +/- 18 x 10(9)/L) was significantly lower than survivors (194 +/- 27 x 10(9)/L, p < 0.005). Multiple regression analysis showed that thrombocytopenia was a risk factor for mortality, independent of the APACHE II score. The presence of DIC surprisingly was not an independent risk factor. We conclude that DIC and thrombocytopenia are common in our adult Medical Intensive Care patients with sepsis, but only the latter is a prognostic factor in addition to the APACHE II score. The incidence of DIC in our patients (mainly Chinese) seems to be more than that of 10 to 20% reported in other series of Caucasian patients. We would, therefore, like to emphasise the importance of platelet count as an prognostic risk factor in sepsis.

Adolescent↗
PubMed1993

Prospective study of the aetiology of adult community acquired bacterial pneumonia needing hospitalisation in Singapore.

A prospective survey of 96 consecutive adult patients with community acquired pneumonia requiring hospitalisation was carried out at National University Hospital, Singapore. Causative pathogens were identified in 58% of patients. Mycobacterium tuberculosis was the most common pathogen (21%), followed by Streptococcus pneumoniae (12%), Haemophilus influenzae (5.2%), Mycoplasma pneumoniae (5.2%) and Staphylococcus aureus (4.2%). Gram-negative organisms (apart from Haemophilus influenzae) were found in 10% of pneumonia patients. More than half of the patients had pre-existing illness, the most common was diabetes mellitus (21%).

Adolescent↗
PubMed1992

The effect of platelet activating factor antagonist on ozone-induced airway inflammation and bronchial hyperresponsiveness in guinea pigs.

We investigated the role of platelet-activating factor (PAF) in ozone-induced airway responses by examining the effects of L659,989, a potent PAF antagonist, on bronchial hyperresponsiveness and airway inflammation. Twenty-four male guinea pigs were studied in four equal groups. Total lung resistance (RL) in intubated and spontaneously breathing animals was measured in a constant-volume body plethysmograph. Dose-response curves to methacholine were determined in all animals at the start of the experiment. These were repeated on a separate day after the following types of treatments: air exposure in Group 1, intraperitoneally administered alcohol and air exposure in Group 2; intraperitoneally administered alcohol and ozone exposure in Group 3, and intraperitoneally administered L659,989 (a specific PAF antagonist), 5 mg/kg dissolved in alcohol, and ozone exposure in Group 4. Bronchoalveolar lavage (BAL) was performed after the second methacholine challenge, and the bronchial mucosa was also examined for inflammatory cells. Exposure to 3 ppm ozone for 2 h resulted in a three-doubling concentration increase in bronchial responsiveness, which was not significantly inhibited by prior treatment with L659,989. Ozone induced a 1.8-fold increase in BAL total cell count, increased eosinophilic influx into the airways, and increased eosinophilic infiltration in the bronchial mucosa, which were all not inhibited by L659,989 pretreatment. The results suggest that PAF may not have an essential role in ozone-induced airway hyperresponsiveness and nonallergic airway inflammation.

Animals↗
PubMed1992

Single-dose and steady-state effects of controlled-release salbutamol on drug level and airflow obstruction in patients with asthma.

Oral medication remains the mainstay of treatment for many asthmatics. We compared the single dose and steady-state effects of twice daily 4 mg and 8 mg controlled-release salbutamol (CRS) on plasma salbutamol and FEV1 in 10 asthmatic patients in a double-blind, double-dummy, cross-over study. On 5 separate days, one week apart, we measured FEV1 and plasma salbutamol hourly for 12 hours after a single dose and, after twice daily doses (4 mg, 8 mg or placebo CRS) for one week. Controlled-release salbutamol showed controlled release properties and dose effect for the two doses. At steady-state, it provided relatively constant plasma levels for 12 hours. Significant and similar bronchodilatation occurred after both 4 mg and 8 mg CRS taken either as a single dose or a steady-state regime.

Adolescent↗
PubMed1992

Choices and preferences in asthma management.

We conducted a questionnaire survey of the management of asthma among doctors in Singapore to determine the trend and range of prescribing habits. Standardised questionnaires were sent to 3,153 medical practitioners registered with the Singapore Medical Council. The overall response rate was 25.3% (797 out of 3,153 doctors). The data were grouped and analysed according to one of 4 respondent-defined groups: (1) non-specialist general practitioners (NS-GP); (2) non-specialists (house officers, medical officers and specialist-in-training) who worked in MOH hospitals (NSMOH); (3) chest specialists; (4) non-respiratory specialists. Patients tended to underestimate the severity of their disease. Inhaled or nebulised beta-agonist was the treatment of choice for acute severe asthma in adults and children for all 4 groups of respondents. In the maintenance treatment for chronic asthma, inhaled and oral beta-agonists and oral theophylline were the mainstay of treatment for adults and children. Nocturnal asthma was similarly treated. The use of inhaled steroids was variably conservative and was reserved for situations where bronchodilators proved inadequate.

Asthma↗