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Biomedical subjects

T H Koh

Publications and source records attributed to T H Koh.

13 recordsLinked to original sources
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↗
PubMed1990

Acute effects of electromagnetic stimulation of the brain on cortical activity, cortical blood flow, blood pressure and heart rate in the cat: an evaluation of safety.

The influence of repeated high intensity electromagnetic stimulation of the brain on cortical activity, cortical blood flow, blood pressure and heart rate has been investigated in the cat, to evaluate the safety of the method. The observations have been made in preparations under propofol anaesthesia before, during and after periods of anoxia. Electromagnetic stimulation of the brain evoked activity in descending motor pathways and was recorded by activity in the median nerve and by muscle twitches. Following repeated series of high intensity stimulation there were no systematic changes in somatosensory evoked potentials or background EEG, nor were there signs of epileptogenic activity during electromagnetic stimulation, before, during or after periods of anoxia. No systematic changes in cortical blood flow, blood pressure or heart rate were observed during electromagnetic stimulation, before or after periods of anoxia. In conclusion, no acute adverse consequences following electromagnetic stimulation in the normal and anoxic cat brain were demonstrated.

Animals↗
PubMed1990

Coronary angioplasty in ischaemic heart disease.

Since its inception a decade ago, Coronary Angioplasty has been shown to be an effective and increasingly preferred method of coronary revascularisation. In order for all physicians involved in the care of cardiac patients to be aware of the relatively new technique we have discussed the indications, advantages and limitations of Coronary Angioplasty. It is only by careful assessment of the patient, international as well as local operator experience, that the appropriate method of coronary revascularisation can be decided for the patient.

Angioplasty, Balloon, Coronary↗
PubMed1990

Thrombolytic therapy in myocardial infarction.

Since its reintroduction in 1979, the administration of streptokinase for the treatment of myocardial infarction has revolutionised the management of this common condition. Intracoronary, and subsequently intravenous infusion of this lytic agent have been shown to recanalise the totally occluded infarct related vessel. Overall mortality reduction was 18% when it was administered intravenously in the GISSI study. The survival advantage has been maintained over 1-2 years. The addition of aspirin has increased the survival rate, as reported in the ISIS-2 study. Recombinant tissue plasminogen activator, a clot specific agent, achieves a higher patency rate when compared to streptokinase, besides favourably influencing survival. Both drugs also improve left ventricular function. Complications include a 0.5-1% incidence of intracranial haemorrhage, as well as a small risk of major bleeding. Although the incidence is low, reinfarction is increased after thrombolytic therapy. Hence, some form of assessment of residual myocardial ischaemia should be performed. Routine PTCA after thrombolysis has not been shown to be of additional benefit. The introduction of more potent and clot specific drugs without unwanted side effects are eagerly awaited.

Animals↗
PubMed1989

PTCA--the initial 100 cases in the Singapore General Hospital.

Percutaneous transluminal coronary angioplasty (PTCA) is an increasingly important technique for the treatment of patients with coronary artery disease. One hundred cases of PTCA were performed in Singapore General Hospital between 1985 to September 1988. 87% were males and 13% were females. The mean age of these patients were 55 +/- 9 SD years (range from 28 to 79 years). 85% had angina pectoris, 43% had a previous myocardial infarction and 12% received intravenous streptokinase previously. One hundred and twenty-nine lesions were dilated. 51% of the cases had single, 40% had double and 9% triple vessel disease. 83% had single, 16% double and 1% triple vessel dilatation. The distribution of the cases by vessel location was 64% for LAD, 19% for RCA and 17% for CX. Overall lesion success was 86%, with an increment in the success rate from 76% in 1987 to 89% in 1988. Similarly, the clinical success rate was 86% for the whole group; it increased from 74% to 90% from 1987 to 1988. The mean diameter stenosis was decreased from 86 +/- 14% SD predilatation to 28 +/- 28% SD postdilatation (p less than 0.005). The mean transtenotic gradient was reduced from 60 +/- 17 mmHg SD predilatation to 18 +/- 11 mmHg SD postdilatation (p less than 0.005). There were 14 failures (14%), the majority of which were due to inability transversing the lesion with a guide wire or balloon catheter. Fourteen complications (14%) occurred in these 100 cases of PTCA. 3% required emergent/semiemergent surgical revascularization. There was no mortality. PTCA is now an established mode of therapy for coronary artery disease in Singapore General Hospital.

Adult↗
PubMed1988

Maturation of corticospinal tracts assessed by electromagnetic stimulation of the motor cortex.

The motor cortex can be excited in adults using electromagnetic stimulation, and the latency to the evoked muscle action potential allows an assessment of the integrity of corticospinal tracts. We applied this technique in children to describe the maturation of corticospinal tracts. The latency from cortical stimulation to the onset of the evoked muscle action potentials and the subject's height were recorded. The subject's height was divided by the latency to the onset of the evoked muscle action potential to provide an index of the conduction velocity within descending motor pathways (VI). It is possible to evoke muscle action potentials after electromagnetic stimulation of the motor cortex in children including preterm babies and there is a stepwise increase in the sensitivity to stimulation between 8 and 11 years of age. In addition there is a progressive increase in VI with age; adult values are attained at about 11 years. The successful application of this technique in children suggests that electromagnetic stimulation of the motor cortex has the potential to allow detection of abnormality in motor pathways in newborn babies and young children.

Adolescent↗
PubMed1988

Neural dysfunction during hypoglycaemia.

There is controversy over the definition of hypoglycaemia in neonates and children and over its significance when 'asymptomatic'. We measured sensory evoked potentials in relation to blood glucose concentration in 17 children: 13 were fasted or given insulin to investigate endocrine or metabolic abnormalities and four had spontaneous episodes of hypoglycaemia. Abnormal evoked potentials were recorded in 10 of the 11 children whose blood glucose concentration fell below 2.6 mmol/l; five of these 10 children were 'asymptomatic'. No change in evoked potentials was recorded in the six children whose blood glucose concentration remained above 2.6 mmol/l. Our findings suggest that the blood glucose concentration should be maintained above 2.6 mmol/l to ensure normal neural function in children irrespective of the presence or absence of abnormal clinical signs.

Adolescent↗
PubMed1988

Neonatal hypoglycaemia--the controversy regarding definition.

Major paediatric textbooks and the views of neonatologists in the United Kingdom were surveyed to establish a definition of neonatal hypoglycaemia. The definition ranged from a glucose concentration of less than 1 mmol/l to less than 4 mmol/l. Hypoglycaemia is recognised to cause neurological sequelae and yet there is no accepted definition of the lower limit of normality for circulating blood glucose concentrations.

Blood Glucose↗
PubMed1986

Pancreatoblastoma in a neonate with Wiedemann-Beckwith syndrome.

The association of pancreatoblastoma and Wiedemann-Beckwith syndrome has not been noted previously. In this report we describe a child with Wiedemann-Beckwith syndrome who had a pancreatoblastoma resected on day 27 of life. He is also the first reported case of Wiedemann-Beckwith syndrome in a black baby.

Beckwith-Wiedemann Syndrome↗
PubMedDate not supplied

Cognitive-perceptual treatment of exceptional children.

Adopting the notion that cognitive operations consist of multiple stages of information-processing, this treatment is designed to specify the locus and nature of the child's deficits in information processing and to compensate for these deficits. Our own clinical and empirical observations, as well as the findings of others, have convinced us that this treatment programme can be applied to exceptional children of many different diagnoses, including emotionally disturbed, learning disabled, autistic, and mentally retarded. A case study involving a seven-year-old autistic child is presented to illustrate the technique, process, and effectiveness of the treatment programme.

Autistic Disorder↗