Index-matched IWKB method for the measurement of spatially varying refractive index profiles within thin-film photovoltaics.

In many thin-film photovoltaic devices, the photoactive layer has a spatially varying refractive index in the substrate-normal direction, but measurement of this variation with high spatial resolution is difficult due to the thinness of these layers (typically 200 nm for organic photovoltaics). We demonstrate a new method for reconstructing the depth-dependent refractive-index profile with high spatial resolution (~10 nm at a wavelength of 500 nm) in thin (200 nm) photoactive layers by depositing a relatively thick index-matched layer (1-10 µm) adjacent to the photoactive layer and applying the Inverse Wentzel-Kramers-Brillouin (IWKB) method. This novel technique, which we refer to as index-matched IWKB (IM-IWKB), is applicable to any thin film, including the photoactive layers of a broad range of thin-film photovoltaics.

Comparison of histology between recurrent tonsillitis and tonsillar hypertrophy.

To elucidate the aetiology of tonsillar hypertrophy and recurrent tonsillitis, it is important to determine whether a difference exists between these two conditions in microanatomical architecture. The aim of this study was to investigate the difference in follicle size and numbers in tonsils for patients with tonsillar hypertrophy and recurrent tonsillitis using an image analysis method. Our results showed that there was no significant difference in the mean follicle numbers per counting field (40x magnification) between recurrent tonsillitis (4.5 +/- 2.1) and tonsillar hypertrophy (3.8 +/- 0.5). However, the mean follicle area in the tonsillar hypertrophy group (0.23 +/- 0.02 mm2) is significantly (P < 0.01) larger than in the recurrent tonsillitis group (0.15 +/- 0.02 mm2). Our study demonstrates that tonsillar hypertrophy is characterized histologically by an enlargement of follicles compared with chronic tonsillitis, indicating a hyperplastic condition of lymphoid cells in the germinal centres. It may also explain the difference in aetiology and/or immune defence mechanism underlying these two conditions.

Environmental risk factors and gender in nasal polyposis.

The aetiology of nasal polyps remains obscure. Although clinically associated with asthma, notably in women, there is a marked male preponderance of polyposis. This study aimed to explore environmental pollutant triggers and gender differences in risk factors for nasal polyps. In total, 900 patients having surgery for polyposis and 120 new patients with nasal polyps completed a questionnaire with regard to occupational dust and chemical exposure. The male to female ratio was 2:1, and 52% were smokers, although only 37% of women smoked compared with 66% of men. Exposure to occupational dusts and chemicals was noted in 45% (retrospective) and 53% (prospective) of respondents. Women were 1.6 times more likely to be asthmatic and 2.7 times more likely to have allergic rhinitis than men. Men were 2.25 times more likely to be smokers and 2.48 times more likely to have been exposed to chemicals and dusts than women (all statistically significant differences). No significant gender associations were found for hayfever, eczema, aspirin intolerance, alcohol intake or hobby dust exposure.

Juvenile angiofibroma: case report and the role of endoscopic resection.

Juvenile angiofibroma is benign yet aggressive. Due to its inaccessible location in the nasopharynx, open surgery usually requires osteotomies which cause stunting of facial growth in adolescent males. Advances in imaging and treatment techniques have now facilitated more accurate staging of this disease. For small, extracranial tumours limited to the nasal cavity and paranasal sinus, endoscopic resection is a viable alternative. This case report will illustrate how endoscopic resection allows good control with minimal morbidity compared to open surgery or radiotherapy.

Variance analysis applied to a stroke pathway: how this can improve efficiency of healthcare delivery.

INTRODUCTION: Stroke is a complicated disease that requires a multidisciplinary approach for its management. We postulated that variance analysis applied to a stroke pathway, by identifying major problem areas and encouraging timely corrective actions, would lead to more efficient healthcare delivery to hospitalised stroke patients. MATERIALS AND METHODS: Prospectively collected variance data from consecutive stroke patients discharged from a tertiary hospital in Singapore during a 3-month period in 2000 were used to identify the major variances causing increased length of stay. These were compared and contrasted to variance data collected during the same 3-month period in the subsequent year (2001), after the implementation of stroke pathway and the availability of monthly variance analysis reports. Patient characteristics and outcome measures were also compared between the two study periods. RESULTS: The four major variances that accounted for increased length of stay were, in descending order of the number of patients affected, awaiting bed availability in step-down facilities, delay in head computed tomographic scan performance, awaiting family's decision on discharge plan and incomplete application submitted to step-down facilities. After implementation of the stroke pathway with ongoing variance analysis, all four variances showed different extent of improvements. There were no significant differences in patient characteristics between the two study periods, whereas the average length of stay significantly diminished in the late study period with a trend for decreased in-hospital mortality, compared to the early study period. CONCLUSION: Variance analysis applied in the context of a stroke pathway was effective in identifying major variances causing increased length of stay. This allowed targeted intervention to improve efficiency of healthcare delivery to stroke patients.

The mastectomy clinical pathway: what has it achieved?

INTRODUCTION: The mastectomy clinical pathway was developed to optimise the clinical care and cost management of breast cancer patients. The aim of this study was to prospectively assess the effect of the mastectomy pathway at the National University Hospital, Singapore over a 7-month period. MATERIALS AND METHODS: A prospective study was carried out on all breast cancer patients admitted for elective mastectomy between March and October 2001. As surrogates of optimised cost and care management, the length of stay and hospital costs, as well as the incidence of complications and unscheduled readmissions, were analysed. Non-pathway mastectomy patients treated from March to October 2000 were used as controls. A total of 83 patients who underwent mastectomy formed the pathway group, while 69 non-pathway patients acted as controls. RESULTS: Compared to controls, the mean length of hospital stay decreased significantly from 4.91 days to 4.10 days (P = 0.018) and the mean cost per case decreased significantly from $5,050 to $4,406 (P = 0.014) for those in the pathway group. There were no significant differences in the complications and unscheduled hospital readmission rates between the two groups (P > 0.05). CONCLUSION: The implementation of mastectomy clinical pathway has improved consistency in patient's treatment, the quality of patient outcome, and has reduced the costs of care and length of hospital stay. In addition, variance analysis of the mastectomy pathway has shown to be valuable for problem identification to improve patient care.

Acute epiglottitis in the tropics: is it an adult disease?

Acute epiglottitis has traditionally been described as a paediatric disease in reports from temperate countries. There have been very few reports from tropical countries. This is a retrospective review of 32 cases of acute epiglottitis from Singapore over an eight-year period from 1992 to 1999. There were 31 adults and only one child. In Singapore, Haemophilus influenzae Type b (Hib) immunization in not routine, and thus the increased prevalence in adults cannot be attributed to Hib immunization. Eleven patients required airway intervention, of whom nine had endotracheal intubation and two had a surgical airway. Significant predictors for airway intervention included the sex of the patient, stridor, presence of airway compromise on examination and a "thumb sign" on the lateral neck radiograph. In adults, selective airway intervention is recommended as those without airway compromise at presentation recover very well with medical treatment alone.

Nasal polyposis: role of subclinical delayed food hypersensitivity.

Nasal polyposis is a common problem in otolaryngology. The cause remains unclear, and treatment with medication and surgery is often unsatisfactory. We present our controlled study, which suggests a strong association between food allergy and nasal polyposis. The study was conducted in 2 parts. A postal survey of 900 patients with nasal polyps showed 53 respondents (5.9%) had a known food allergy. In the prospective study, 80 nasal polyp patients and 36 control subjects completed intradermal tests for food allergy. Sixty-five nasal polyp patients (81%) and 4 control subjects (11%) had positive intradermal food test results. This is highly significant. We believe that food allergy may play a significant role in the pathogenesis of nasal polyposis and should be further studied.

Ectopic multinodular goitre.

A 61-year-old man presented with a slowly enlarging lateral neck mass. There was no other associated ENT symptoms. Clinical examination was unremarkable. The pan endoscopy was normal. The mass when excised was found to be subplatysmal. The histology was that of a multinodular thyroid tissue. Subsequent investigations showed normally placed thyroid with multinodular changes. Laterally placed thyroid tissue have been reported since the 18th century. Initially, they were found to contain malignant tissue and hence the term lateral aberrant thyroid tumours. In later years, benign ectopic thyroid tissue was described in the lateral neck. It is now felt that ectopic thyroid tissue are derived from thyroid cell rests that have failed to fuse with the main thyroid tissue during development. They are subjected to the same goitrogenic stimulation as the normally placed thyroid tissue. Our case supports the view that not all laterally placed thyroid tissue are malignant.

Do antral washouts have a place in the current management of chronic sinusitis?

Antral washouts have been widely used in the management of chronic sinusitis. With the advent of modern antibiotics and powerful topical nasal steroids, we sought to establish if a role remains for this procedure. One hundred and fourteen patients with chronic sinusitis were randomised into two groups. Patients in Group A received antral washouts followed by antibiotics and topical nasal steroids. Patients in the Group B received antibiotics and topical nasal steroids alone. In each group 51.6 per cent and 50 per cent of patients respectively improved with treatment. The outcome of treatment is also not influenced by endoscopic abnormality. The difference was not statistically significant (p = 0.86). The study indicates that half of patients with chronic sinusitis will improve with medical treatment but the addition of antral washout confers no additional benefits.

Acute suppurative parotitis and facial paralysis.

A case of facial nerve paralysis secondary to acute suppurative parotitis is described. This is a rare complication in the absence of malignant processes in the parotid.

Laser reduction of inferior turbinates in children.

Perennial nasal obstruction in children refractory to medical treatment may be managed by turbinate reduction. Turbinectomy may involve a risk of significant postoperative bleeding and requires nasal packing. Submucosal diathermy is followed by nasal congestion and crusting; recurrent nasal obstruction is frequent at fifteen months. This study assesses the benefits of carbon dioxide laser reduction of inferior turbinates in 20 children. Intraoperative blood loss was negligible and no nasal packing was required. There was minimal postoperative discomfort which required no analgesia. No postoperative haemorrhage was recorded. The children were able to drink and eat by 4 and 6 hours respectively. Relief of nasal obstruction occurred one to seven days postoperatively and was confirmed by rhinohygrometry. Nasal patency was maintained on eighteen to twenty-four months follow up. Mucosal healing was completed by four weeks. Mucosal saccharin clearances were normal postoperatively. We conclude laser turbinectomy is an excellent means of turbinate reduction in selected children.

Paediatric tonsillectomy: bipolar electrodissection and dissection/snare compared.

Tonsillectomy is a common operation in children performed by a variety of techniques. Recently we have introduced a modified form of electrodissection tonsillectomy using bipolar diathermy. A prospective study was designed to evaluate this technique against the conventional dissection/snare technique. Sixty children were entered into each section of the study (total 120 children). There is a statistically significant shorter operating time (mean 11.2 minutes) and lower intraoperative blood loss (mean 5 ml) using the bipolar diathermy technique. Post-operatively, the children who had bipolar diathermy tonsillectomy were found to be able to drink and eat significantly earlier than the cold dissection group. There was no measurable difference in analgesia requirements before discharge and the time of discharge between the two methods. Post-operative haemorrhage occurred in two out of 60 (3.4 per cent) and one out of 60 (1.7 per cent children) in the conventional and bipolar diathermy dissection, respectively, but this was not statistically significant.

Surgical treatment of tympanosclerosis.

Tympanosclerosis as a cause of conductive hearing loss may require corrective surgery in carefully selected cases, although results of treatment have been controversial and must be viewed with caution. Currently available surgical techniques are reviewed and outcomes discussed.

Bipolar diathermy tonsillectomy.

Tonsillectomy is an operation performed by various techniques. We have developed a bipolar diathermy dissection technique that allows a low intra-operative blood loss without an increase in complications. The average blood loss was less than 4 ml in 100 patients. Most were able to drink and eat by 4 and 10 hours respectively. There was no increase in analgesic requirements. No primary haemorrhage was recorded; three patients had a secondary haemorrhage. The technique allows accurate coagulation of blood vessel and is an easy procedure to learn.

Current considerations in the etiology and diagnosis of tympanosclerosis.

Current concepts of formation of tympanosclerosis in the middle ear are reviewed, as are various clinical considerations. Ultrastructural changes are discussed. A differential diagnosis includes disorders affecting middle ear sound conduction, with the most prevalent involving otosclerosis and cholesteatoma.