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Biomedical subjects

I K Tan

Publications and source records attributed to I K Tan.

At least 37 records · Page 2Linked to original sources
PubMed1995

Superimposed inspiratory work of the Siemens Servo 300 ventilator during continuous positive airway pressure.

OBJECTIVE: To compare the superimposed inspired work of breathing (SIW) of the Siemens Servo 300 ventilator with the Siemens Servo 900 C ventilator. DESIGN: Comparisons made at continuous positive airway pressure (CPAP) levels of 0, 4, and 8 cmH2O, and at trigger sensitivities of -1 and -2 cmH2O, and flow triggering. SETTING: General intensive care unit in a University teaching hospital. PATIENTS: 7 patients receiving CPAP. At all levels of CPAP, the SIW was significantly less with the Siemens Servo 300 ventilator as compared to the Siemens Servo 900 C ventilator despite similar trigger sensitivities. No significant difference was found in the SIW of the Servo 300 ventilator when comparing trigger sensitivities of -1 cmH2O, -2 cmH2O, and flow triggering. Different levels of CPAP had no effect on SIW. CONCLUSIONS: The Siemens Servo 300 ventilator entails less superimposed inspiratory work of breathing than the Siemens Servo 900 C ventilator.

Adult↗
PubMed1995

The effect of recombinant growth hormone on nitrogen balance in malnourished patients after major abdominal surgery.

The effect of recombinant growth hormone (rGH) on nitrogen balance was studied in malnourished patients receiving total parenteral nutrition after major abdominal surgery. Fifteen patients were randomized to receive either subcutaneous rGH (0.2 iu/kg) or placebo (saline) injection daily for seven days after surgery. Positive nitrogen balance was achieved throughout the treatment period with rGH administration and was significant on days 3 and 6. This was associated with increase in mid-arm muscle circumference and significant weight gain. Plasma insulin-like growth factor-1 (IGF-1) concentration was significantly raised in the rGH group at day 7, suggesting its role in the anabolic effect of growth hormone. Plasma pre-albumin and retinol-binding protein concentrations were raised in both the rGH and control groups, indicating improvement in the nutritional status. We conclude that the postoperative catabolic response can be attenuated using recombinant growth hormone.

Abdomen↗
PubMed1995

Use of prostate specific antigen (PSA) and transrectal ultrasound (TRUS) in the diagnosis of prostate cancer--a local experience.

Prostate specific antigen (PSA) and transrectal ultrasound (TRUS) are two new modalities added to improve our ability to diagnose prostate cancer at an early stage. We reviewed our own experience of 100 cancers among 579 men from August 1991 to October1994. The detection rate was 17.3%. Digital rectal examination (DRE) alone had a positive predictive value (PPV) of 39.9%. The PPV for PSA was 23%. The combination of PSA and DRE gave a PPV of 47.2%. TRUS had a PPV of 30.6%. Features of cancer on TRUS may be both hypoechoic or hyperechoic nodules which appeared to have almost equal proportions associated with cancer. The addition of age-specific ranges did not affect the PPV of PSA. The PPV of the combination of TRUS and DRE was 53%. With all 3 modalities combined, the PPV was 58.8%. An interesting finding from the study was the higher average PSA for benign and malignant disease in the local population and cases of acute retention of urine. There was a higher incidence of prostatitis and lower incidence of cancer in cases with retention of urine.

Adult↗
PubMed1993

Effects of PEEP on dynamic hyperinflation in patients with airflow limitation.

We have studied the effects of extrinsically applied PEEP (PEEPe) and intrinsic PEEP (PEEPi) on lung volume and peak airway pressure (Paw,peak) in 10 patients with airflow limitation during mechanical ventilation. PEEPe was applied in 2-4 cm H2O increments until values greater than PEEPi were reached. Total lung hyperinflation was quantified by measuring the expired volume resulting from deflation (starting at end inspiration) until cessation of expiratory flow. The previous expired tidal volume was subtracted from this volume to obtain the change in functional residual capacity (delta FRC), the hyperinflation resulting from PEEPi and PEEPe. PEEPi (0.49-1.66 kPa) was demonstrated in all patients before the application of PEEPe and correlated with delta FRC (r = 0.71), with delta FRC increasing by 582 ml/kPa PEEPi (P < 0.05). PEEPe at pressures less than PEEPi increased delta FRC by (mean) 186 (SEM) 34 ml/kPa PEEPe (P < 0.05) and increased Paw,peak by 0.6 (0.12) kPa/kPa PEEPe (P < 0.05). In contrast, PEEPe at pressures greater than PEEPi, increased delta FRC by 695 (128) ml/kPa PEEPe (P < 0.05) and Paw,peak by 1.8 (0.26) kPa/kPa PEEPe. We conclude that PEEPe may be applied cautiously at values less than PEEPi when clinically indicated, but the application of PEEPe at values greater than PEEPi may substantially aggravate lung hyperinflation.

Aged↗
PubMed1992

Serum magnesium, copper, and zinc concentrations in acute myocardial infarction.

This study was carried out to assess the serum levels of magnesium, copper, and zinc after an acute episode of myocardial infarction. Determination of the metal concentrations were carried out on 41 patients with myocardial infarction and 41 healthy controls matched for age and sex. A slight decrease in the mean level of magnesium (P less than .05) was observed in patients (2.0 mg/dl) compared with the controls (2.1 mg/dl). The mean serum copper concentration was significantly higher (P less than .001) in patients (138 micrograms/dl) than in controls (98 micrograms/dl), while the mean serum zinc concentration was significantly lower (P less than .001) in patients (75 micrograms/dl) than in controls (100 micrograms/dl). The differences in serum copper and zinc levels between patients and controls were magnified considerably when the copper/zinc ratios were calculated for both groups (P less than .001). The mean copper/zinc value obtained for patients (1.91) was almost double that for the controls (1.02).

Adult↗
PubMed1991

Growth and the production of penicillins in Penicillium chrysogenum with palm oil and its various fractions as carbon sources.

The utilisation of palm oil and its fractions by Penicillium chrysogenum for growth and penicillin production is strain-dependent. Strain H1107 could utilise crude palm oil, its liquid (palm olein) and solid (palm stearin) fractions and its component fatty acids (oleic, palmitic, stearic and myristic) as the main carbon source; strain M223 could not. Cell-bound lipase activity was higher in H1107 than in M223.

Fatty Acids↗
PubMed1991

Local norms of maternal serum alpha-fetoprotein values in early second trimester: a prelude to a Down's syndrome screening programme incorporating maternal serum alpha-fetoprotein values.

Maternal alpha-fetoprotein in (MSAFP) has recently been proposed for screening of Down's syndrome. This is based on the association of a lowered MSAFP level at a given gestational age in Down's syndrome (DS) pregnancies. Most conventional 'screening' programmes in DS are based on the maternal age alone, selecting older mothers, who are at greater risk of having a DS infant born, for antenatal karyotyping. However, as 75% of DS infants are born to mothers less than 35 years old, a combination of blood tests including MSAFP and maternal age as independent risk factors would screen the younger mothers as a good cost-benefit ratio in selecting the 'at-risk' mothers for karyotyping. In this study, the gestational age was calculated from the first day of the last menstrual period (LMP) as well as from ultrasound cephalometry. The local MSAFP levels follow the same trend at a slightly higher level as those based on clinical evaluation of the Abbot AFP-EIA Monoclonal kits.

Down Syndrome↗
PubMed1990

Use of computers in quality assurance of laboratory testing.

Implementation of comprehensive internal quality control programmes and participation in external quality assessment schemes to monitor analytical performance of laboratory tests have been widely accepted as an essential and integral part of good laboratory practice. As these programmes involve a great deal of repetitive statistical calculations and graphic presentation of data on quality control materials, many laboratories and practically all organisers of inter-laboratory quality assessment schemes increasingly rely on computers to handle the burdensome processing of data and to provide timely feedback in a manner that is easily understood and readily interpreted by analytical staff. However, in spite of the best effort to ensure reliable analytical performance, spurious and misleading results can still occur as a result of non-analytical errors which are not readily detected by methods designed to monitor the quality of analytical process. The use of sophisticated computer system has enabled our laboratory to check for the existence of some of these errors. This paper describes the application of computers in a variety of internal and external quality assessment programmes and demonstrates the usefulness of retrieving patients' cumulative test results and at the same time performing delta or percentage difference checks on such data in the detection of non-analytical errors and unexpected variations in results. The role of the computer in minimising transcription errors, reducing turn-around time of testing and reporting, as well as improving the quality of laboratory reports is also mentioned.

Clinical Laboratory Information Systems↗
PubMed1989

Clinical biochemistry in Singapore.

During the period from 1982 to mid-1989, there has been very significant changes and improvement in the practice and application of clinical biochemistry in Singapore. This paper highlights recent developments in the repertoire of biochemical analyses, utilisation of laboratory tests, biochemical screening in preventive health care, handling and delivery of patient specimens, advances in analytical techniques, automation, computerisation, quality assurance, training of laboratory personnel, and professional activities. It also draws attention to the restructuring of the Singapore General Hospital and the government Department of Pathology which frees these government institutions from the constraints of the civil service so that they would be sufficiently flexible to respond readily to the changing needs and expectations of the patients and users of laboratory services. This is the most prominent event and policy change in the history of health care services in Singapore that is expected to result in more cost-effective utilisation of resources and greater improvement in the quality of health care.

Automation↗
PubMed1988

The use of serum transferrin in the evaluation of protein-calorie malnutrition in cancer patients.

Forty-five patients with various malignancies of the gastrointestinal tract had their nutritional status assessed pre-operatively to determine the prevalence of malnutrition and to establish the correlation of malnutrition with post-operative outcome. Ten nutritional parameters were assessed. Based on these markers, we found a significant degree of malnutrition. Half of the study population developed some form of post-operative complication and nearly one quarter died. Of the ten nutritional markers studied, only serum transferrin had predictive value in determining post-operative outcome. The mean level of serum transferrin for patients with major complications was 162.0 mg/dl as compared with 221.2 mg/dl for those with none or minor complications. Patients with a serum transferrin level below the reference range of 200 mg/dl had most of the major life threatening complications and deaths. The other nutritional markers studied did not correlate well with post-operative outcome. We feel that serum transferrin is a useful nutritional marker to predict post-operative outcome and also to monitor the effect of nutritional support. However, based on a preliminary study, nutritional support may be required for periods longer than two weeks to show significant improvement in protein-calorie malnutrition. We will consider giving adequate support for a longer period on a further study using serum transferrin as a marker to determine its value in monitoring any reversal of malnutrition.

Female↗
PubMed1986

Computers in clinical laboratory management in Singapore.

In 1974, an off-line mini-computer system was introduced in the Clinical Biochemistry Laboratories of the Government Department of Pathology in Singapore. With the resiting of the 24-hour emergency biochemistry laboratory on the same floor as the Haematology Department within the new Singapore General Hospital, an on-line computer system was installed in 1983 to serve both the emergency biochemistry and haematology laboratories. An almost identical on-line system was also purchased in 1984 to replace the aged off-line system at the Department of Pathology. A description of the new computer systems based on Eclipse S/140 computers and Medical Information Technology (Meditech) software using Meditech Interpretive Information System (MIIS) language will be given. The specific features required and the selection criteria for the on-line systems are also discussed. The systems are used for the acquisition and processing of all patient and test data of the laboratories, direct capture of data from automated instruments, generation of work schedules and laboratory reports, compilation of work done, workload and revenue statistics and a variety of other reports. Patient cumulative records and quality control statistics are available on a real-time basis, thus greatly facilitating enquiries on patient results and monitoring of analytical performance. Prior experience with an off-line system and careful planning have been helpful in greatly shortening the preparatory period required for the smooth implementation of the on-line systems. Use of the systems has significantly improved laboratory management and has resulted in improved quality, and higher efficiency and productivity.

Chemistry, Clinical↗
PubMed1984

Quality assurance in the Third World--the Singapore experience.

This paper reviews the current status of quality assurance in clinical biochemistry laboratories in Third World countries, particularly the developments in Singapore which in some respects are very similar to those of other developing countries. Some of the common problems are highlighted and recommendations for improvement proposed.

Asia↗
PubMed1984

Reference values for 24 biochemical constituents of children in Singapore.

Reference values are essential for interpretation of biochemical data on patients. Due to various problems, such values could not be obtained for the local paediatric population. This study was carried out to establish reference values for 24 biochemical constituents using blood specimens obtained from 352 Singapore children who were assessed to be free from any disease that may affect the values. For a number of biochemical constituents, reference values were also calculated for the different age groups. These values are compared with the local adult values established by the same methods.

Blood Chemical Analysis↗
PubMed1982

Clinical biochemistry in Singapore--past and present.

This paper traces the historical development of the practice of clinical biochemistry in Singapore and presents the current status of the special branch of laboratory medicine in the country. The rapid expansion in the field which has taken place over the last three decades, has no parallel in any other medical specialty. This has presented unique problems. The approaches taken to solve these problems are described and the following areas are highlighted: scope of biochemical investigations, research and development, methodology and instrumentation, laboratory workload, automation and computerisation, costing of laboratory service, reference values, quality control, training, education, international relations and professional activities.

Chemistry, Clinical↗