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Biomedical subjects

W C Tan

Publications and source records attributed to W C Tan.

At least 91 records · Page 5Linked to original sources
PubMed1991

Pharmacokinetics of oral salbutamol controlled-release in Asian patients with asthma.

Using a double blind, double dummy crossover design, single dose and steady state pharmacokinetics of oral controlled release (SCR) salbutamol 4 mg and 8 mg tablets b.d. has been studied in 8 Asian patients. Plasma salbutamol was measured over 12 h. In 8 patients the single dose mean Cmax was 4.2 ng.ml-1 and 7.7 ng.ml-1 after 4 and 8 mg, respectively. In 5 patients the steady state mean Cmax, Cmin and tmax were 8.1 ng.ml-1 and 4.7 ng.ml-1 and 6 h for the 4 mg tablets and 14.1 ng.ml-1 and 7.1 ng.ml-1 and 4 h for the 8 mg tablets. It is concluded that both doses of SCR show features of controlled release and that they produced a relatively constant plasma level of salbutamol in Asian patients.

Administration, Oral↗
PubMed1991

Evaluation of obstructive sleep apnoea in Singapore using computerised polygraphic monitoring.

There is no information of the prevalence and severity of obstructive sleep apnoea (OSA) in Asian snorers. One reason is the complexity and cost of a full polysomnographic recording. We have studied 37 snorers using an ambulatory recording system (Vitalog CA). Overnight recordings for seven hours were made of: 1) Respiratory pattern using respiratory inductance plethysmography; 2) Heart rate from the electrocardiograph (ECG); 3) Body position; 4) Body movements; 5) Oxygen saturation using finger-probe oximetry. The data were stored and analysed and scored using a dedicated microcomputer. Twenty-eight patients had OSA based on polygraphic criteria. The most consistent clinical findings in these patients were daytime somnolence and short thick necks. Respiratory events, oximetry and arousals during sleep showed a graded response according to the severity of excessive daytime somnolence. We conclude that OSA may not be uncommon in Asian patients and that the clinical severity can be confirmed by simplified polygraphic recordings using microcomputer analysis.

Adult↗
PubMed1991

Rational drug strategy in bronchial asthma.

The emphasis in the treatment of bronchial asthma has shifted from that of bronchial hyper-responsiveness to that of airway inflammation. Bronchodilators still form the mainstay of treatment for all categories of asthma. However, only anti-allergic drugs and corticosteroids can modify inflammation and long-term usage offers the hope of suppression of the disease and prevention of progressive airway obstruction. The safety of inhaled steroids has enabled specific treatment to be extended to milder asthma. Correct treatment will not succeed without patient compliance and good inhaler technique. The ultimate aim of therapy is the reduction of morbidity and mortality and the prevention of irreversible airway obstruction.

Asthma↗
PubMed1990

Analgesia and respiratory function following intrapleural bupivacaine after cholecystectomy.

Analgesia and pulmonary function following intrapleural bupivacaine were compared with those following intramuscular pethidine in thirty-four patients after cholecystectomy. The patients were randomly allocated to two groups of seventeen patients each to receive either intrapleural bupivacaine or intramuscular pethidine. The positions of seventeen intrapleural catheters inserted were confirmed by chest radiography. Two out of seventeen catheters were found to be located in the extrapleural space. It was also recognized by fluoroscopy that phrenic nerve palsy did not develop on patients given intrapleural bupivacaine. The subjective quality of analgesia following intrapleural bupivacaine was significantly better than that following intramuscular pethidine. The mean duration of analgesia obtained after each injection of bupivacaine was 4.68 hr (range 3.5-6.1 hr). Forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV 1), which decreased markedly in the postoperative period improved significantly after being given bupivacaine or pethidine. But there was no significant difference in the improvement of FVC and FEV 1, between both groups in spite of the higher percentage of pain relief in the intrapleural bupivacaine group. All respiratory function tests studied thirty days after surgery were not significantly different when compared with those before surgery.

Clinical Trial↗
PubMed1990

Effect of sleep and sleep deprivation on ventilatory response to bronchoconstriction.

To characterize ventilatory responses to bronchoconstriction during sleep and to assess the effect of prior sleep deprivation on ventilatory and arousal responses to bronchoconstriction, bronchoconstriction was induced in eight asthmatic subjects while they were awake, during normal sleep, and during sleep after a 36-h period of sleep deprivation. Each subject was bronchoconstricted with increasing concentrations of aerosolized methacholine while ventilatory patterns and lower airway resistance (Rla) were continually monitored. The asthmatic patients maintained their minute ventilation as Rla increased under all conditions, demonstrating a stable tidal volume with a mild increase in respiratory frequency. Inspiratory drive, as measured by occlusion pressure (P0.1), increased progressively and significantly as Rla increased under all conditions (slopes of P0.1 vs. Rla = 0.249, 0.112, and 0.154 for awake, normal sleep, and sleep after sleep deprivation, respectively, P less than 0.0006). Chemostimuli did not appear to contribute significantly to the observed increases in P0.1. Prior sleep deprivation had no effect on ventilatory and P0.1 responses to bronchoconstriction but did significantly raise the arousal threshold to induced bronchoconstriction. We conclude that ventilatory responses to bronchoconstriction, unlike extrinsic loading, are not imparied by the presence of sleep, nor are they chemically mediated. However, prior sleep deprivation does increase the subsequent arousal threshold.

Adult↗
PubMed1990

Effects of spontaneous and simulated gastroesophageal reflux on sleeping asthmatics.

We examined the effect of intraesophageal acid (either spontaneous gastroesophageal reflux or infused) on airflow resistance in 15 sleeping asthmatic subjects. We observed no significant acute or sustained changes in airflow resistance relative to periods of intraesophageal acid. Overnight changes in spirometry and lower airway resistance also demonstrated similar nocturnal worsening of bronchoconstriction despite the occurrence of spontaneous or simulated gastroesophageal reflux. The presence or absence of clinical evidence of esophagitis (Bernstein test response) did not alter the observed lack of response to intraesophageal acid. We conclude that gastroesophageal reflux contributes little to the nocturnal worsening of asthma.

Adult↗
PubMed1990

Bilateral spontaneous pneumothorax in systemic sclerosis--report of two cases.

We describe 2 patients with systemic sclerosis who developed bilateral spontaneous pneumothoraces. Though unilateral spontaneous pneumothorax has been described, the problem has not been emphasized recently and the complication of bilateral spontaneous pneumothoraces has not been documented. Treatment of the pneumothorax is difficult and reexpansion of the lung is slow. This complication is associated with a poor prognosis as both patients had severe respiratory impairment and one died shortly afterwards.

Adult↗
PubMed1990

Idiopathic bronchiolitis obliterans with organizing pneumonia in Singapore--first case report.

Idiopathic bronchiolitis obliterans organizing pneumonia (BOOP) has become accepted as a distinct disease entity. We report a patient who presented with the classical clinical, radiological and pathologic features of this uncommon condition. To our knowledge, this is first case to be reported in Singapore. This case also illustrates the difficulty of making a definitive diagnosis and emphasizes its therapeutic importance.

Aged↗
PubMed1990

The efficacy of high dose inhaled budesonide in replacing oral corticosteroid in Asian patients with chronic asthma.

We studied 22 Asian patients with steroid dependent asthma. Using a clinical approach to the addition of high dose inhaled budesonide and tapering of systematic steroid, we were able to substitute 5 to 20 mg prednisolone with 800 micrograms per day of inhaled budesonide in all patients. There was also a greater reduction in nocturnal symptoms and awakenings and a smaller overnight fall in PEFR during treatment with budesonide than with prednisolone. Inhaled budesonide was an effective long term substitute for prednisolone in chronic asthma.

Administration, Inhalation↗
PubMed1990

Baker's asthma: a case report.

Bakers are known to experience respiratory complaints ranging from allergic rhinitis to chronic bronchitis and asthma. We report here the first confirmed case of baker's asthma in Singapore. The patient is a 40 year-old Chinese male, working at a biscuit factory for the last 14 years as a mixer. He developed asthmatic attacks five years after joining the factory and had been on bronchodilators and oral steroids. He was confirmed to have occupational asthma due to wheat flour, following a bronchial challenge test. He was subsequently transferred to another section and there was marked improvement in the frequency of attacks and the peak expiratory flow rate. This case illustrates the need to consider workplace factors in the diagnosis and management of asthma among the working population. Medical treatment alone is insufficient in the management of occupational and work-related asthma.

Adult↗
PubMed1989

Histoplasmosis presenting as hyperplastic gingival lesion.

A case of histoplasmosis presenting as ulcerated, hyperplastic gingiva and with no other systematic signs and symptoms is reported. The clinical presentation and the rarity of this condition led one of us to the differential diagnosis of a malignant lesion. The correct diagnosis was made after histological examination and tissue culture which yielded Histoplasma capsulatum. The patient was successfully treated with ketoconazole.

Adult↗
PubMed1989

[Respiratory function in idiopathic scoliosis in adolescents treated by Harrington instrumentation with or without sublaminar segmental wiring].

The forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC) of 40 adolescents with idiopathic scoliosis were studied before and after surgery. The values obtained are expressed as percentages of the predicted normal. Twenty-one patients underwent surgical correction of the curve with Harrington rods followed by cast and brace immobilisation for one and a half years (Group A). In the other 19 patients the Harrington rod was contoured in the sagittal plane and supplemented with segmented sublaminar wires to allow rapid post-operative mobilisation free of any orthosis (Group B). A negative correlation was found pre-operatively between the magnitude of the curve and the FEV1 and FVC. The post-operative pulmonary function showed no statistically significant improvement. Contouring the Harrington rod to improve kyphosis in Group B did not affect the outcome.

Adolescent↗
PubMed1987

Double-blind comparison of the protective effect of sodium cromoglycate and ketotifen on exercise-induced asthma in adults.

In a double-blind double-placebo study 10 asthmatics exercised on a treadmill after treatment for 1 week with placebo, or ketotifen 1 mg twice daily, or SCG 10 mg four times daily. The post-exercise percentage fall in FEV1 after SCG but not after ketotifen was significantly smaller than after placebo. A 1-week treatment with SCG but not ketotifen protected against EIA.

Adolescent↗
PubMed1987

Inhaled corticosteroids in the management of chronic bronchial asthma.

Inhaled corticosteroids have become a standard treatment for chronic severe asthma in adults and in children. In patients whose symptoms are not controlled by beta 2 agonist, theophylline preparations and disodium cromoglycate, inhaled corticosteroids can either reduce the need of or substitute for oral corticosteroids. Inhaled corticosteroids are not effective in an acute asthmatic attack when oral corticosteroids are indicated. Patients who are not adequately treated with conventional doses of inhaled corticosteroids may benefit from high dose inhaled corticosteroids.

Administration, Inhalation↗
PubMed1987

The role of the fibreoptic bronchoscope in the diagnosis of bronchial neoplasm.

We report our experience from January 1980 to December 1985 with the fibreoptic bronchoscope in the evaluation of bronchial disease, particularly bronchial neoplasm. Bronchoscopy was performed in 456 patients (329 men, 127 women) and the pathological results were analysed retrospectively. The main indications for bronchoscopy were the radiological findings of a central mass (22%), a peripheral mass (18%), lobar or segmental collapse (14%), unresolved pneumonia (13%), and haemoptysis as a symptom (15%). Abnormal bronchoscopic findings were noted in 167 patients. This was supported by histological examination in 136 patients (81%). In 43 patients (32%) the diagnosis was only made on cytology. The clinical predictive values of common indications were: central mass 0.53, lobar or segmental collapse 0.51, and superior vena cava obstruction 0.36. The fibreoptic bronchoscope is a highly efficient method for diagnosing bronchial malignancy. Bronchial brushing and aspiration should be performed in all cases to maximise the yield.

Adult↗
PubMed1985

The role of climatic conditions and histamine release in exercise-induced bronchoconstriction.

We examined the role of climatic conditions on exercise induced asthma in patients in the tropics. Ten asthmatic patients exercised on a cycle ergometer achieving similar maximal heart rates, oxygen consumption, work load, and minute ventilation on three occasions, breathing warm humid air, cool drier air and cold dry air. Blood for plasma histamine was collected before and after exercise breathing cold air. The exercise-induced bronchoconstriction (EIB) was least in warm air, maximal in cold air and intermediate in cool air. Post exercise venous histamine was raised in only 2 out of 7 patients. We conclude that temperature and humidity have a direct role in EIB and that mediator release is probably the result rather than the cause of EIB.

Adolescent↗