Biomedical subjects
W C Tan
Publications and source records attributed to W C Tan.
The role of fibreoptic bronchoscopy in the management of respiratory burns.
We found that fibreoptic bronchoscopy was a useful, simple, safe and accurate method in the diagnosis of inhalation injury, determining the type, the site and the extent of damage sustained. The most common mucosal damage was erythema and oedema of the supraglottic and glottic tissues, though in a few cases more severe and extensive injury was seen. Death seemed to be determined largely by the extent of skin burn but since there did not appear to be a close relationship between the severity of skin burn and the presence of inhalation burn, we suggest that the two types of injuries be evaluated separately. The main therapeutic role lies in the assessment and anticipation of imminent upper airway obstruction caused by oedema of the supraglottic tissues and the glottis. Endotracheal intubation could then be carried out promptly. Changes in clinical features and laboratory results were too slow to be of use in the prediction of upper airway obstruction, but could be indirect indicators of lower and peripheral airway injury.
The obstructive sleep apnoea syndrome: case studies.
We describe the upper airway abnormalities and sleep observations of cardiorespiratory function in six patients with the obstructive sleep apnoea syndrome. They were all men, the youngest had evident upper airway obstruction from enlarged tonsils while the rest had no gross mechanical obstruction on direct laryngoscopy but had demonstrable abnormalities of flow-volume loop recordings. Sleep studies demonstrated marked cyclical variation of heart rate and arterial oxygen desaturation. These were associated with loud snoring and cyclical hyper-ventilation and hypo-ventilation. These features were characteristic of the obstructive sleep apnoea syndrome. This paper documents the classic features of the obstructive sleep apnoea syndrome in an Oriental population.
Acute carbon dioxide narcosis during inhalational therapy with oxygen powered nebulizers in patients with chronic airflow limitation.
Six patients with acute carbon dioxide narcosis following nebulised salbutamol therapy were described. They had chronic obstructive airflow disease and were admitted in acute respiratory failure. The patients were treated with aerosolized salbutamol delivered from oxygen powered nebulizers. They developed severe acute hypercapnia. Five of the six patients died. The hazards of indiscriminate oxygen use in this clinical situation was discussed.
Spontaneous pneumothorax in medical practice in a general hospital.
Eighty patients with spontaneous pneumothoraces treated in the University Department of Medicine, Singapore General Hospital from January 1981 to March 1983 were reviewed. There were 75 males and 5 females. Their ages ranged from 15 to 92 years. Dyspnea was the chief representing symptom in 59 patients (74%) followed by chest pain in 47 patients (59%). One patient was admitted with loss of consciousness. Pneumothorax with no discernable associated disease was present in 36 patients (45%) whereas 34 (43%) had chronic obstructive airways disease. Of the remaining 10 patients, active pulmonary tuberculosis was present in 5, bronchogenic carcinoma in 2, bronchial asthma in 2 and bronchopneumonia in 1 percent. Pneumothorax occurred equally on both sides. Single episode of pneumothorax was present in 64 patients (80%). Recurrent pneumothoraces were only present in 16 patients (20%). 57 patients (71%) required chest tube insertion while 14 patients (18%) in addition required either medical or surgical pleurodesis. Death occurred in 6 patients (7.5%) mainly in those with chronic obstructive airways disease. In this study the majority of pneumothoraces occurred in patients with either no underlying pulmonary disease or those with chronic obstructive bronchitis and emphysema. A bimodal age presentation was noted, with the younger patients having no underlying respiratory disorders.
Spirometric pulmonary function tests before and after surgical correction of idiopathic scoliosis in adolescents.
Severe scoliosis causes a deterioration in cardiopulmonary function. The effect of surgical correction on this is variable. We studied the forced vital capacity [FVC) and forced expiratory volume in one second (FEV1) before and after surgical correction in 30 adolescents with idiopathic scoliosis and the results are expressed as a percentage of the predicted normal values using 101 children as controls. A negative correlation was noted preoperatively between the magnitude of the curve and FVC and FEV1. Surgical correction of the curve was done with a Harrington rod in 17 patients followed by cast and brace immobilisation for one and a half years. In the remaining 13 patients the Harrington rod was supplemented with sublaminar wires (SSI) to eliminate the use of an orthoses. All patients had a posterior spinal fusion. Our study showed that there was an improvement in the spirometric values post-operatively but this was not statistically significant. This improvement was similar in both groups of patients. Further studies, for a longer period and of other indices of pulmonary function are required.
A case of pneumonia presenting with the acute respiratory distress syndrome.
Adult respiratory distress syndrome (ARDS) or high permeability pulmonary oedema (HPPE) is an uncommon presentation of a viral pneumonia and usually occurs in the setting of a fulminant or severe viral pneumonia. High permeability pulmonary oedema (HPPE) can be loosely defined as those forms of pulmonary oedema with normal cardiac function associated with the accumulation of protein-rich fluid in the interstitial or intraalveolar spaces. Through the years, a number of phrases have been used to describe this entity: white lung, shock lung, wet lung, adult hyaline membrane disease, ARDS and others. The aetiology is varied but the clinical, radiologic and pathologic pictures are similar. In fact the pathologic picture is so consistent from patient to patient regardless of aetiology that it has been suggested that the term HPPE be used in place of the other commonly used ones. A case of HPPE of possible viral aetiology who responded to prompt intervention with a successful outcome, is described here.
Cardiopulmonary resuscitation at the Singapore General Hospital.
Effective use of Cardiopulmonary Resuscitation (CPR) saves lives both in and out of hospitals. Yet, in Singapore, this practical skill is rarely taught even within the medical community. Observations from a CPR pilot training programme at the Singapore General Hospital expose this glaring deficiency in our health system. Urgent remedial measures are needed.
Sporadic disseminated histoplasmosis simulating miliary tuberculosis.
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The role of sympathomimetic amines in the dyspnoea of thyrotoxicosis.
Nine untreated thyrotoxic patients (5 males and 4 females) aged 23 to 56 years who complained of dyspnoea on moderate exertion were studied. Measurements of forced expiratory volume (FEV1), vital capacity (VC) and total lung capacity (TLC), oxygen consumption, (VO2), carbon dioxide output (VCO2) and the minute ventilation (VE) were determined on three occasions: before treatment; after treatment with propranolol and after carbimazole. Dyspnoea disappeared in 4 patients out of 9 after treatment with propranolol, while none were dyspnoeic when they became euthyroid. There was no significant difference in FEV1, VC, TLC and FRC on the three occasions. The differences between the VO2, VCO2 and VE before treatment and these values after treatment with carbimazole were significant. We conclude that the dyspnoea of thyrotoxicosis is due to both the effect of catecholamines and the metabolic effect of thyroxine.
The prevalence of skin sensitization to Aspergillus antigens among asthmatic patients in Singapore.
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Protective effect of drugs on bronchoconstriction induced by sulphur dioxide.
The response to inhaled sulphur dioxide in eight normal, seven atopic, and 22 asthmatic subjects was studied by measuring thoracic gas volume and airway resistance in a whole-body plethysmograph. The fall in specific airway conductance in relation to the concentration of sulphur dioxide inhaled (0-20 ppm) was determined in all three groups. The specific airway conductance fell significantly in the atopic and asthmatic subjects but not in the normal group. In a double-blind study prior inhalation of disodium cromoglycate caused a significant reduction in the response to sulphur dioxide inhalation in atopic and asthmatic subjects. Prior treatment with inhaled ipratropium bromide blocked the response in the atopic subjects, but the effect was variable in the patients with asthma. Previous treatment with inhaled clemastine also reduced the response in patients with asthma, without causing a change in baseline specific conductance. We conclude that non-allergic bronchial hyperreactivity was increased in the atopic and the asthmatic subjects and that mediator release, in addition to a vagal reflex, has a role in such bronchoconstriction.
Cortical blindness complicating acute nephritis - a case report and electrophysiological study.
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Patterns of pneumonia in Singapore General Hospital.
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Surveillance of human mitral valve cells by autochthonous lymphocytes, in vitro.
Analysis of a time-lapse film of cultured human mitral valve endothelium containing autochthonous lymphocytes reveals details of a pattern of interaction suggesting a previously undescribed type of cellular surveillance. Highly mobile lymphocytes rapidly approach individual endothelial cells, slowly circumnavigate the nuclear region, and rapidly move away to repeat this behavior on adjacent cells during the 1-month culture period.
Histopathologic study of adverse effects of linoleic acid on rat lung.
Linoleic acid administered intravenously was highly toxic to the rat lung. The severity of the toxicity paralleled the dosage administered and was characterized by generalized, irreversible damage to alveolar wall structures. Although evidence of tissue damage was not apparent or minimal by light microscopy, ultrastructural studies disclosed extensive degeneration and necrosis of septal wall components with 15 minutes following injection of low dosages of linoleic acid. Degeneration of endothelial cells was most severe suggesting that these cells were the target of injury resulting in impaired vascular integrity, interstitial and alveolar edema, and degeneration of type 1 pneumocytes. Fragmentation and stripping of endothelium from capillary basement membranes was uniformly present and was in some instances associated with platelet aggregation indicative of early thrombosis. These studies suggest that this toxic effect on septal capillaries leading to increased permeability and alveolar edema may be a contributing factor to death occurring from free fatty acid toxicity in the human.
An analysis of skin prick test reactions in asthmatics in Singapore.
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Prick skin tests in bronchial asthma and their correlation with the specific serum IgE levels.
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