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Biomedical subjects

P Eng

Publications and source records attributed to P Eng.

At least 19 recordsLinked to original sources
PubMed2000

Endobronchial stenting in patients requiring mechanical ventilation for major airway obstruction.

OBJECTIVE: To examine the value of therapeutic rigid bronchoscopy on subsequent ventilator weaning in ventilated patients with major airway obstruction. MATERIALS AND METHODS: Retrospective review of the medical records of patients who were receiving mechanical ventilation up to the time of rigid bronchoscopy over the period from September 1994 to January 1999. The setting is in an acute tertiary hospital. All patients underwent rigid bronchoscopy with endoscopic techniques (forceps removal, balloon dilation Nd:YAG laser resection and stent insertion) aimed at restoration of major airway patency. RESULTS: Seven patients were identified; 2 with benign stenosis and 5 with malignant stenosis. Six out of the 7 patients had presented with acute respiratory distress requiring emergent intubation, whilst 1 patient had extubation difficulties following general anaesthesia with endotracheal intubation. Three out of the 7 patients had previously failed extubation attempts. All 7 patients were successfully extubated within 48 hours following the procedure. CONCLUSIONS: Therapeutic rigid bronchoscopy is effective in the acute management of respiratory distress from central airway obstruction. Dramatic improvements in ventilatory status following therapeutic rigid bronchoscopy allow ventilator liberation in a select group of patients with an otherwise good performance status.

Adult↗
PubMed1999

Induction chemotherapy followed by concurrent chemoradiotherapy in stage III unresectable non-small cell lung cancer.

The favourable experience with the combination regimen of vinorelbine, ifosfamide and cisplatin (NIP) in patients with metastatic non-small cell lung cancer (NSCLC) has led to a protocol assessing this regimen as an induction treatment in patients with stage III unresectable NSCLC, followed by thoracic radiotherapy with concurrent daily cisplatin as a radiosensitizer. Two cycles of NIP were administered 21 days apart; each cycle comprised i.v. vinorelbine 25 mg/m2 on days 1 and 8, i.v. ifosfamide 3 g/m2 on day 1 with MESNA as uroprotection, and i.v. cisplatin 50 mg/m2 on day 1. Radical thoracic radiotherapy commenced on day 43 to a total dose of 64 Gy and i.v. cisplatin 6 mg/m2 was given concurrently prior to each fraction of radiation as a sensitiser. Two more cycles of NIP were given to patients who responded favourably to the induction treatment about 2 weeks after completion of radiation. Between July 1995 and July 1997, 44 patients were treated with this protocol. This treatment schedule was generally well tolerated. Grade 3-4 neutropenia occurred in 50% of the patients and neutropenic sepsis was seen in 8. Grade 3-4 oesophagitis was uncommon. Most of the patients were able to complete the induction and concurrent chemoradiotherapy phase. Major response occurred in 75% of the patients with 2 (4.5%) complete responses (CR). A total of 6 patients achieved CR after chemoradiotherapy. At a median follow-up of 35 months, the median overall survival for all patients was 15 months with a 3-year survival rate of 24%. The median overall survival for stage IIIA patients was 19 months with a 3-year survival rate of 39% in contrast to 13 months' median overall survival and only 15% 3-year survival rate for stage IIIB. The NIP regimen results in a high response rate in NSCLC and this treatment programme seems to benefit selected patients with stage III disease.

Adult↗
PubMed1999

NAT2 slow acetylator genotype is associated with increased risk of lung cancer among non-smoking Chinese women in Singapore.

Among non-smokers, the factors resulting in lung carcinogenesis are poorly understood. We conducted a hospital-based case-control analysis of 294 Chinese women, of whom 217 were non-smokers, to evaluate the role of polymorphic N-acetyltransferase (NAT2) as a susceptibility factor for the disease. The proportion of slow acetylator genotypes among non-smoking cases (n = 92) and controls (n = 125) was 38.0 and 24.0%, respectively [odds ratio (OR) 2.0, 95% confidence interval (CI) 1.1-3.7]. No effect of NAT2 genotype was seen among smokers. Among non-smokers, the effect was marked for adenocarcinomas (OR 2.1, 95% CI 1.1-4.0). As NAT2 activity is known to modify risk of arylamine-induced carcinogenesis, our results suggest that exposure to arylamines in the environment may play a role in risk of lung cancer among non-smokers.

Acetylation↗
PubMed1999

Neural network prediction of obstructive sleep apnea from clinical criteria.

STUDY OBJECTIVES: Clinical prediction models for the diagnosis of obstructive sleep apnea (OSA) have lacked the accuracy necessary to confidently replace polysomnography (PSG). Artificial neural networks are computer programs that can be trained to predict outcomes based on experience. This study was conducted to test the hypothesis that a generalized regression neural network (GRNN) could accurately classify patients with OSA from clinical data. STUDY DESIGN: Retrospective review. SETTING: Regional sleep referral center. PATIENTS: Randomly selected records of patients referred for possible OSA. MEASUREMENTS: The neural network was trained using 23 clinical variables from 255 patients, and the predictive performance was evaluated using 150 other patients. RESULTS: The prevalence of OSA in this series of 405 patients (293 men and 112 women) was 69%. The trained GRNN had an accuracy of 91.3% (95% confidence interval [CI], 86.8 to 95.8). The sensitivity was 98.9% for having OSA (95% CI, 96.7 to 100), and the specificity was 80% (95% CI, 70 to 90). The positive predictive value that the patient would have OSA was 88.1% (95% CI, 81.8 to 94.4), whereas the negative predictive value that the patient would not have OSA (if so classified) was 98% (95% CI, 94 to 100). CONCLUSIONS: Appropriately trained GRNN has the ability to accurately rule in OSA from clinical data, and GRNN did not misclassify patients with moderate to severe OSA. In this study, use of the neural network could have reduced the number of PSG studies performed. Prospective validation of the neural network for the diagnosis of OSA is now required.

Adolescent↗
PubMed1998

Transudative malignant pleural effusions: prevalence and mechanisms.

BACKGROUND: Malignant pleural effusions are classically exudative, though occasionally they can be transudative. We attempted to determine the prevalence of transudative malignant pleural effusions and to describe their clinical and radiographic characteristics. METHODS: We studied the medical records of 215 patients with malignant pleural effusion, which contained complete data on pleural fluid analysis for 171 of them. RESULTS: Eight cases of transudative malignant effusion were found. Seven of these eight patients had a concomitant disorder known to cause transudative pleural effusion. One patient had fluid overload due to renal failure, and another had been admitted earlier with congestive heart failure. Two patients had definite evidence of deep venous thrombosis, allowing us to postulate pulmonary embolism as a factor contributing to transudation. Three patients had CT evidence of superior vena cava obstruction. Only one patient had no known associations with causes of transudative effusion. CONCLUSION: Malignant pleural effusions were transudative in 5% of our patients. In all except one patient, some evidence suggested the concomitant presence of a transudative state.

Aged↗
PubMed1998

Albuterol delivered by metered-dose inhaler (MDI), MDI with spacer, and Rotahaler device--a comparison of efficacy and safety.

A randomized double-blind, triple crossover study was conducted on 20 asthmatic patients (7 males and 13 females; age 40.9 +/- 14.2 Caucasians, 11 blacks, and 1 oriental. Criteria for admission included FEV1 < or = 80% of predicted when inhaled beta-agonists were witheld for at least 6 hrs and oral beta-agonists for 12 hr, in addition to at least 15% increase in FEV1, 15 min after treatment with albuterol with spacer delivery. Each of the study patients were tested on each of 3 separate days (within the same week) at baseline, 15, 30, 60, 120, 180, 240, 300, and 360 min post treatment. On each day albuterol was delivered by one of the 3 delivery devices and the other two methods delivered placebo. Albuterol was administered at the maximum recommended dosages of two puffs for MDI. Two puffs for MDI with spacer, and two capsules for Rotahaler. Spirometry, blood pressure and heart rate were measured at each testing interval. The mean percentage in FEV1 was higher in Rotahaler group compared to MDI with spacer (p < 0.001) and no significant difference in FEV1 was found between Rotahaler and MDI alone (p = 0.31). No significant changes in heart rate or blood pressure were associated with albuterol delivery by any of the three methods. Albuterol inhaled as a microfine powder was more effective than the same drug delivered as an aerosol by either MDI or MDI with spacer.

Adult↗
PubMed1998

Case series of bronchoscopic removal of tracheobronchial foreign body in six adults.

Tracheobronchial foreign body is rare in adults. Diagnosis is difficult and requires a high index of suspicion. We report 6 cases of tracheobronchial foreign bodies in adults and their removal, as well as a literature review of this topic. Case records, chest radiographs and computed tomographies (CT) of the thorax were reviewed. There were 5 males and 1 female with a median age of 63.5 years. One patient could not protect his airway (tracheostomy). Foreign bodies were sutures (2), vegetable matter like peanuts, vegetables and popcorn (3), and a voice prosthesis. Main symptoms were cough, haemoptysis and breathlessness. There were few signs on physical examination and chest X-rays were not helpful in diagnosis. All patients had fibreoptic bronchoscopy although 3 subsequently required rigid bronchoscopy for foreign body removal. All foreign bodies were successfully removed without any complications.

Aged↗
PubMed1998

Malaria requiring intensive care.

We studied 24 consecutive adult patients with malaria who required intensive care between 1 January 1994 and 31 December 1997. This was out of a total of 256 patients hospitalised at the Singapore General Hospital with malaria during these 4 years. Our aim was to characterise the type and severity, clinical features, complications, treatment and outcome of adult patients with malaria who required intensive care. In addition, we compared the actual and predicted mortality based on the Acute Physiology and Chronic Health Evaluation II (APACHE II) score. The travel history, prophylaxis, duration of fever before receiving treatment, type of malaria and severity, clinical data, complications, APACHE II score, treatment and outcome were analysed. Most cases were imported by locals travelling overseas or foreigners infected with the parasite elsewhere. Four patients had vivax malaria and 20 patients had severe falciparum malaria. All but 1 patient received transfusion with blood products and 6 patients with severe falciparum malaria had exchange transfusions. Complications were restricted to infection with P. falciparum: 9 patients required acute dialysis and 8 required mechanical ventilation. Three patients died giving a mortality of 15% for severe falciparum malaria. The overall mortality of patients with malaria was 1.2%. The mortality of patients with malaria requiring intensive care was 12.5% as compared with a predicted mortality of 18.7% based on the APACHE II prognostication system.

APACHE↗
PubMed1998

The oxygen delivery debate--a review.

Tissue hypoxia is an important cause for the development of multisystem organ failure in the critically ill. Achieving adequate haemodynamic support of oxygen demand is the mainstay of treatment in these patients. Controversies regarding therapeutic end-points do exist but in general maintaining oxygen delivery by ensuring adequate cardiac output, oxygen saturation and haemoglobin is important in the critically ill.

Critical Care↗
PubMed1997

Chylothorax: case report and review of literature.

Chylothorax is a relatively uncommon condition. We report a case of a 53-year-old Chinese man with chylothorax who presented with cough, breathlessness, loss of weight and generalised lymphadenopathy. He was initially diagnosed as having tuberculosis based on histology and cultures of the cervical lymph node. However, immunophenotyping of the pleural fluid by flow cytometry showed the presence of a monoclonal B cell population with Kappa light chain expression suggesting an underlying lymphoproliferative disorder. A repeat lymph node biopsy showed malignant lymphoma (follicular small cleaved type). In spite of aggressive measures which included bilateral tube thoracostomy drainage, a low fat diet, medium chain triglyceride diet, total parenteral nutrition, chemotherapy and mediastinal irradiation, his chylothorax persisted. Hence, we report a patient with persistent chylothorax and generalised lymphadenopathy who was subsequently diagnosed to have concurrent tuberculosis and malignant lymphoma. The literature on chylothorax is reviewed.

Biopsy↗
PubMed1997

Vocal cord dysfunction: two case reports.

Vocal cord dysfunction is an uncommon condition characterised by adduction of vocal cords that can masquerade as or coexists with bronchial asthma. The glottic dysfunction is due to a functional (non-organic) cause. If unrecognised, incorrect diagnosis may result in patients being unnecessarily treated as refractory or severe asthma with high doses of corticosteroid. This may result in unwarranted steroid toxicity. Clues that should raise clinical suspicion to the diagnosis of vocal cord dysfunction include lack of response to bronchodilators, poor reproducibility of spirometric indices due to inconsistent effort and truncation of the inspiratory limb of the flow-volume loop. Definitive diagnosis is made by direct visualisation of the vocal cords during an attack. We report two patients with vocal cord dysfunction and review the literature on this disorder.

Adolescent↗
PubMed1997

Current concepts in ventilator-associated pneumonia.

Ventilator-associated pneumonia (VAP) is a common problem in the intensive care unit (ICU). It is associated with a distinct spectrum of pathogens and its pathogenesis involves microaspiration of oropharyngeal organisms. Clinical and radiographic criteria have been shown to be unreliable in diagnosing VAP, and it remains a challenge for intensivists to utilise the array of diagnostic procedures at their disposal to optimise diagnostic accuracy (improve specificity) and guide in therapy. These procedures and guided antibiotic therapy may not always improve the outcome and therefore simple preventive measures should be employed to reduce the incidence.

Humans↗
PubMed1996

Ideal endotracheal tube placement by referencing measurements on the tube.

The ideal position of the endotracheal tube (ETT) within the trachea is 5 +/- 2 cm from the carina with the head and neck in neutral position (Goodman's criteria). We assessed the possibility of achieving ideal placement of ETTs in our population by positioning them at reference marks of 23 cm in men and 21 cm in women. From January 1995 to April 1995, 105 intubated patients in the Medical Intensive Care Unit, Singapore General Hospital were studied. The mean distance of the ETT tip from the carina was 4.02 cm +/- 3.90. The ETT tip was < 3 cm from the carina in 30 cases (28.6%) with one case resulting in endobronchial intubation. These 30 patients were significantly shorter in height when compared to the rest of the study population (P = 0.01). Five cases (4.8%) had ETT tip > 7 cm from the carina. Adopting the above-mentioned reference marks did not result in ideal positioning of ETTs in a significant proportion of cases (33.4%). We postulate that this is because our Asian population is generally shorter than those in previous studies which had achieved ideal ETT positioning using similar reference marks.

Body Constitution↗
PubMed1996

Noninvasive positive-pressure ventilation for acute respiratory failure in a medical intensive care unit in Singapore.

The main advantage of noninvasive ventilation over conventional mechanical ventilation is in the avoidance of endotracheal intubation and its related complications. Currently, the role of noninvasive ventilation in the management of patients with acute respiratory failure is still not firmly established. We conducted a prospective study to evaluate the efficacy of nasal positive pressure ventilation in patients with acute respiratory failure. Thirty-three consecutive patients with acute failure in whom intubation and mechanical ventilation were strongly considered were included in the study. They received ventilatory support by means of BiPAP ventilatory support system and nasal mask. Physical findings and laboratory measurements were documented before and at specific intervals after initiation of support. Eighty per cent (24/30) of patients were successfully supported. Successfully supported patients tolerated the device with improved gas exchange, hence avoiding endotracheal intubation. The mean duration of support was 19.2 hours. There were major associated complications, e.g. gastric distention or aspiration.

Acute Disease↗
PubMed1995

Kinetics: our window into the goals and strategies of the central nervous system.

The goal of this chapter is to demonstrate the role of integrated biomechanical analyses in complex movements such as gait in alerting researchers of the goals and synergies of the CNS. Because of the large number of segments involved and the potential for the CNS to take advantage of inter-limb coupling it is only through appropriate biomechanical analyses that such collaboration can be identified. Examples from normal, perturbed, elderly and pathological gait are presented to demonstrate the principles of total limb and total body analysis to pinpoint the goals of the CNS and to identify total limb or body synergies and adaptations in the elderly and in gait pathologies. Such findings reinforce the generalizations made many years ago by Bernstein [2] when he postulated several simplifying principles of CNS control. Also, evident from these analyses are the precision and accuracy of biomechanical variables that make these measures particularly sensitive to small changes within an individual or across a population group.

Adult↗
PubMed1995

Current developments in departmental PACS for ultrasound.

1. INTRODUCTION TO DEPARTMENTAL PACS. Full or partial Departmental PACS is generally taken to mean an image management system focused on serving the needs of a specific modality or modality application. It will provide a modality specific means of image acquisition, specialized redisplay of images, distribution, and local long term storage of images. A Departmental PACS can be considered in isolation or as a component in a distributed Radiology PACS which consists of one or more departmental work groups on a back bone, potentially with shared resources. 2. DEPARTMENTAL PACS Issues Implementation of a Departmental PACS requires an in-depth knowledge of departmental clinical practice and work flow in all affected areas in the department, including patient intake, image collection, data routing, retrieval of previous image data, reporting, and long term data management and storage. Optimization of modality specific image display systems requires significant involvement from representative physician users. System architectures and user interfaces must be flexible enough to support the span of variation in clinical practice encountered in the site. A departmental PACS should offer a variety of "open" communications interfaces, both local and wide area, recognizing that outreach efforts are often driven by specific imaging departments. Interfaces to other departmental PAC systems and other information systems must be considered in order to facilitate institutions developing "Best of Breed" PACS systems. As hospitals move toward the integrated electronic medical record, means need to exist for a client process launched from a physician desktop to acquire images and/or reports from a departmental system. At minimum, HIS/RIS interfaces need to be considered to minimize re-keying of data and reduce data entry errors. 3. DESIGN OBJECTIVES FOR ALI ULTRAPACS. The key objectives were to design a product which could function either as a free standing PACS or as a departmental subnet on a larger PACS backbone, one which could function in a local or mixed local and wide area environment and one which could provide a cost effective implementation based on currently available technologies. 4. IMPLEMENTATION STRATEGIES. In order to attain the product design objectives, ALI made the following critical implementation decisions: 1) to build the UltraPACS application as a suite of separable UNIX processes based on a message passing client server model; 2) to host the application and operating system on a Digital Equipment Corporation PC using an Intel microprocessor because of the competition and broad variety of suppliers in the PC arena; and 3) to use NEXTSTEP as the UNIX variant of choice because of NEXTSTEPUs strong object orientation, superb development tools, and the excellent integration between the Graphical User Interface level and the underlying operating system layers. 5. CONCLUSION. ALI is convinced that a departmental approach to PACS offers significant advantages over monolithic PACS in several key areas including: optimization for modality specific clinical practice and workflow, cost effectiveness, the potential for an institution to implement PACS in a stepwise fashion, starting with the department with the potential for the greatest savings, and the capability for an institution to build a "best of breed" solution for large scale PACS.

Radiology Department, Hospital↗
PubMed1995

Community-acquired pneumonia.

Major changes have occurred in the epidemiology of community-acquired pneumonia recently. The emergence of new pathogens emphasises the need for continued vigilance in the diagnosis of pneumonia while changes in the microorganism or in the host have resulted in exciting new aspects of several old pathogens. Clinical and radiologic signs are unreliable in predicting the infecting organisms. Thus initial therapy is nearly always empiric. This approach often requires good clinical judgement and a knowledge of local epidemiological patterns in choosing an appropriate regimen. State-of-the-art invasive diagnostic procedures are usually reserved for pneumoniae that fail to resolve with initial treatment. Non-specific measures like stabilisation of underlying medical conditions, adequate nutrition and cessation of smoking or alcohol may help prevent the development of community-acquired pneumonia. On a larger scale, influenza and pneumococcal vaccinations are cost-effective preventive measures.

Adult↗