PubMed Health⌕ Search

Biomedical subjects

K K Yau

Publications and source records attributed to K K Yau.

17 recordsLinked to original sources
PubMed2006

Endo-Lap OR: an innovative "minimally invasive operating room" design.

BACKGROUND: A newly constructed Endoscopic-Laparoscopic operating room (Endo-Lap OR) started to operate in our department in January 2005. A prospective study was conducted to evaluate its feasibility, efficacy, and safety, as well as the staff's satisfaction. PATIENTS AND METHODS: From January 2005 to September 2005, all patients undergoing operation in this Endo-Lap OR were included in the study. The patient's diagnosis, types of operating procedures, incidents of operating failure (either due to the hardware or the software of Endo-Lap OR) that led to a delay in the patient's transfer or that extended the total operating time were recorded. In addition, questionnaires regarding staff satisfaction with the new operating room were distributed to nurses, anesthetists, and surgeons. RESULTS: A total of 640 cases were included in the study period, 245 cases of open surgery, 282 cases of laparoscopic surgery, 82 cases of endoscopic surgery, 17 cases of video-assisted thoracoscopic surgery, and 14 cases of combined endoscopic-laparoscopic surgery. There were no reported incidents of operating failure related to hardware or software problems. The overall staff satisfaction was excellent. CONCLUSIONS: The integration of endoscopic and laparoscopic surgery into this newly constructed Endo-Lap OR is feasible and safe. The running of the operating room was smooth and it received a high level of acceptance and satisfaction from different staff members.

Architecture↗
PubMed2005

Immediate preoperative laparoscopic staging for squamous cell carcinoma of the esophagus.

BACKGROUND: Conventional preoperative staging for esophageal carcinoma could be inaccurate. Laparoscopy has been applied for the staging of various upper gastrointestinal malignancies. It can identify peritoneal and liver deposits not shown by imaging, and could reduce the number of nontherapeutic laparotomies. This study aimed to evaluate the efficacy of laparoscopic staging for the management of squamous cell carcinoma involving the mid and distal esophagus. METHODS: A retrospective review was performed for all patients with esophageal cancer evaluated for surgical resection from January 1998 to January 2004. Laparoscopy was performed for all the patients with mid and distal esophageal cancer immediately before open gastric mobilization. The efficacy of laparoscopy for the management of squamous cell carcinoma of the esophagus was evaluated. RESULTS: Among the 63 patients with potentially resectable disease shown on conventional imaging, 54 (84%) underwent esophagectomy with curative intent after laparoscopic staging. Seven patients (11%) underwent laparoscopy alone because of abdominal metastases (n = 5) or other medical conditions (n = 2) that precluded esophagectomy. Two patients (3%) had exploratory right thoracotomy without esophagectomy despite normal laparoscopic findings. The sensitivity and specificity of laparoscopic staging were 100% in this series of patients (100% sensitivity and specificity means no false-positives or -negatives). CONCLUSION: Laparoscopic staging is valuable for the management of patients with mid and distal squamous cell carcinoma of the esophagus. Patients with metastatic disease and those with prohibitive surgical risk can thus avoid unnecessary laparotomy and be offered other treatment methods.

Aged↗
PubMed2005

Acute gastric volvulus: an unusual cause of gastric outlet obstruction.

Gastric outlet obstruction initiated by acute gastric volvulus is rare but potentially fatal. An unusual case of intrathoracic acute gastric volvulus complicated by distal stomach and transverse colon herniation into retrocardial space is reported. Prompt clinical diagnosis was followed by emergency laparoscopic de-rotation and gastropexy.

Journal Article↗
PubMed2001

Zero-inflated Poisson regression with random effects to evaluate an occupational injury prevention programme.

This study presents a zero-inflated Poisson regression model with random effects to evaluate a manual handling injury prevention strategy trialled within the cleaning services department of a 600 bed public hospital between 1992 and 1995. The hospital had been experiencing high annual rates of compensable injuries of which over 60 per cent were attributed to manual handling. The strategy employed Workplace Risk Assessment Teams (WRATS) that utilized a workplace risk identification, assessment and control approach to manual handling injury hazard reduction. The WRATS programme was an intervention trial, covering the 1988-1995 financial years. In the course of compiling injury counts, it was found that the data exhibited an excess of zeros, in the context that the majority of cleaners did not suffer any injuries. This phenomenon is typical of data encountered in the occupational health discipline. We propose a zero-inflated random effects Poisson regression model to analyse such longitudinal count data with extra zeros. The WRATS intervention and other concomitant information on individual cleaners are considered as fixed effects in the model. The results provide statistical evidence showing the value of the WRATS programme. In addition, the methods can be applied to assess the effectiveness of intervention trials on populations at high risk of manual handling injury or indeed of injury from other hazards.

Accidents, Occupational↗
PubMed2001

Long-term survivor mixture model with random effects: application to a multi-centre clinical trial of carcinoma.

A mixture model incorporating long-term survivors has been adopted in the field of biostatistics where some individuals may never experience the failure event under study. The surviving fractions may be considered as cured. In most applications, the survival times are assumed to be independent. However, when the survival data are obtained from a multi-centre clinical trial, it is conceived that the environmental conditions and facilities shared within clinic affects the proportion cured as well as the failure risk for the uncured individuals. It necessitates a long-term survivor mixture model with random effects. In this paper, the long-term survivor mixture model is extended for the analysis of multivariate failure time data using the generalized linear mixed model (GLMM) approach. The proposed model is applied to analyse a numerical data set from a multi-centre clinical trial of carcinoma as an illustration. Some simulation experiments are performed to assess the applicability of the model based on the average biases of the estimates formed.

Carcinoma, Squamous Cell↗
PubMed2001

Determinants of maternity length of stay: a Gamma mixture risk-adjusted model.

With obstetrical delivery being the most frequent cause for hospital admissions, it is important to determine health- and patient-related characteristics affecting maternity length of stay (LOS). Although the average inpatient LOS has decreased steadily over the years, the issue of the appropriate LOS after delivery is complex and hotly debated, especially since the introduction of the mandatory minimum-stay legislation in the USA. The purpose of this paper is to identity factors associated with maternity LOS and to model variations in LOS. A Gamma mixture risk-adjusted model is proposed in order to analyze heterogeneity of maternity LOS within obstetrical Diagnosis Related Groups (DRGs). The determination of pertinent factors would benefit hospital administrators and clinicians to manage LOS and expenditures efficiently.

Diagnosis-Related Groups↗
PubMed2001

Distinct tumour specificity and IL-7 requirements of CD56(-)and CD56(+) subsets of human gamma delta T cells.

gamma delta T cells are believed to recognize tissue injury caused by infections, tumours, as well as chemical and physical agents. The present study was carried out to study the feasibility of the ex vivo expansion of gamma delta T cells from healthy individuals, and to determine their functional capacity against tumours. We selectively expanded the peripheral gamma delta T cells of five donors against a myeloma cell line, XG-7. Under optimal conditions, the resulting bulk cultures comprised about 82% of the gamma delta T cells, more than 90% of which showed the T-cell receptor (TCR)-V gamma 9 delta 2 rearrangement. These gamma delta T-cell cultures exhibited TCR-gamma delta dependent cytotoxicity against different tumour cell lines including Molt-4, BJAB, Epstein-Barr virus (EBV) transformed lymphoid cell lines (LCL), and the nasopharyngeal carcinoma (NPC) cell lines, CNE2 and 915, in addition to the stimulator XG-7. By competitive cytotoxicity assays, the gamma delta T cells demonstrated recognition of at least three distinct target specificities expressed by Molt-4, CNE2 and LCL, respectively, which were related to that expressed by the stimulator XG-7 cells. The recognition of the specificity expressed by XG-7 and Molt-4 was further shown to require the participation of heat shock protein (HSP). The specificity expressed by CNE2 and 915 was preferentially recognized by the CD56 subset of gamma delta T cells, which could be sustained in the presence of interleukin (IL)-7. These results suggested that gamma delta T-cell immunity against tumour cell lines may be acquired in response to other types of tissue injury and, hence, implicates a role for their use in the prevention and treatment of tumours.

Burkitt Lymphoma↗
PubMed2001

Multilevel models for survival analysis with random effects.

A method for modeling survival data with multilevel clustering is described. The Cox partial likelihood is incorporated into the generalized linear mixed model (GLMM) methodology. Parameter estimation is achieved by maximizing a log likelihood analogous to the likelihood associated with the best linear unbiased prediction (BLUP) at the initial step of estimation and is extended to obtain residual maximum likelihood (REML) estimators of the variance component. Estimating equations for a three-level hierarchical survival model are developed in detail, and such a model is applied to analyze a set of chronic granulomatous disease (CGD) data on recurrent infections as an illustration with both hospital and patient effects being considered as random. Only the latter gives a significant contribution. A simulation study is carried out to evaluate the performance of the REML estimators. Further extension of the estimation procedure to models with an arbitrary number of levels is also discussed.

Biometry↗
PubMed2001

Consultative team to assess manual handling and reduce the risk of occupational injury.

OBJECTIVES: To describe the formation of a consultative team to assess the risk of manual handling in the workplace that started in October 1992 within the cleaning services department of a 600 bed hospital, and to evaluate the effectiveness of its recommendations in reducing the rate and severity (time lost and cost) of workers' compensation injury. METHODS: The consultative team identified, assessed, and recommended controls for manual handling and other injury risks. Data on injuries counted before and after implementation of the team's recommendations were obtained for the cleaning services study group, an orderly services comparison group, as well as cleaners from a peer hospital and for the State of Western Australia. Evaluation of the four groups was undertaken 3 years after the end of the study period, to allow maturation of the costs of the claims (adjusted to July 1998 consumer price index) and hours lost from work. RESULTS: Statistical analysis showed that implementation of the recommendations significantly reduced numbers and rates of injury, but not the severity of injury, in the cleaning services study group. There was no difference in numbers or severity of injuries for the comparison groups before and after implementation of the recommendations. CONCLUSIONS: The recommendation of the consultative team can produce a meaningful and sustained reduction in rates of injury within an at risk population. The results support a consultative approach to reducing workplace injuries from manual handling. The team process has potential for application to occupational groups at risk of exposure to other types of hazards.

Accidents, Occupational↗
PubMed2001

Determining the effects of patient casemix on length of hospital stay: a proportional hazards frailty model approach.

OBJECTIVES: To identify factors associated with hospital length of stay (LOS) and to model variations in LOS within Diagnosis Related Groups (DRGs). METHODS: A proportional hazards frailty modelling approach is proposed that accounts for patient transfers and the inherent correlation of patients clustered within hospitals. The investigation is based on patient discharge data extracted for a group of obstetrical DRGs. RESULTS: Application of the frailty approach has highlighted several significant factors after adjustment for patient casemix and random hospital effects. In particular, patients admitted for childbirth with private medical insurance coverage have higher risk of prolonged hospitalization compared to public patients. CONCLUSIONS: The determination of pertinent factors provides important information to hospital management and clinicians in assessing the risk of prolonged hospitalization. The analysis also enables the comparison of inter-hospital variations across adjacent DRGs.

Delivery, Obstetric↗
PubMed2000

Probing peripheral and central cholinergic system responses.

OBJECTIVE: The pharmacological response to drugs that act on the cholinergic system of the iris has been used to predict deficits in central cholinergic functioning due to diseases such as Alzheimer's disease, yet correlations between central and peripheral responses have not been properly studied. This study assessed the effect of normal aging on (1) the tropicamide-induced increase in pupil diameter, and (2) the reversal of this effect with pilocarpine. Scopolamine was used as a positive control to detect age-dependent changes in central cholinergic functioning in the elderly. DESIGN: Randomized double-blind controlled trial. PARTICIPANTS: Ten healthy elderly (mean age 70) and 9 young (mean age 33) volunteers. INTERVENTIONS: Pupil diameter was monitored using a computerized infrared pupillometer over 4 hours. The study involved 4 sessions. In 1 session, tropicamide (20 microL, 0.01%) was administered to one eye and placebo to the other. In another session, tropicamide (20 microL, 0.01%) was administered to both eyes, followed 23 minutes later by the application of pilocarpine (20 microL, 0.1%) to one eye and placebo to the other. All eye drops were given in a randomized order. In 2 separate sessions, a single dose of scopolamine (0.5 mg, intravenously) or placebo was administered, and the effects on word recall were measured using the Buschke Selective Reminding Test over 2 hours. OUTCOME MEASURES: Pupil size at time points after administration of tropicamide and pilocarpine; scopolamine-induced impairment in word recall. RESULTS: There was no significant difference between elderly and young volunteers in pupillary response to tropicamide at any time point (p > 0.05). The elderly group had a significantly greater pilocarpine-induced net decrease in pupil size 85, 125, 165 and 215 minutes after administration, compared with the young group (p < 0.05). Compared with the young group, the elderly group had greater scopolamine-induced impairment in word recall 60, 90 and 120 minutes after administration (p < 0.05). CONCLUSION: There is an age-related pupillary response to pilocarpine that is not found with tropicamide. Thus, pilocarpine may be useful to assess variations in central cholinergic function in elderly patients.

Adolescent↗
PubMed1998

ML and REML estimation in survival analysis with time dependent correlated frailty.

In the study of multiple failure times for the same subjects, for example, recurrent infections for patients with a given disease, there are often subject effects, that is, subjects have different risks that cannot be explained by known covariates. Standard methods, which ignore subject effects, lead to overestimation of precision. The frailty model for subject effects is better, but can be insufficient, because it assumes that subject effects are constant over time. Experience has shown that the dependence between different time periods often decreases with distance in time. Such a model is presented here, assuming that the frailty is no longer constant, but time varying, with one value for each spell. The main example is a first-order autoregressive process. This is applied to a data set of 128 patients with chronic granulomatous disease (CGD), participating in a placebo controlled randomized trial of gamma interferon (gamma-IFN), suffering between 0 and 7 infections. It is shown that the time varying frailty model gives a significantly better fit than the constant frailty model.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Non-operative management of endoscopic iatrogenic haemobilia: case report and review of literature.

Haemobilia denotes an abnormal communication between a vessel of the splanchnic circulation and the biliary system. Patients typically presents with the triad of abdominal pain, upper gastrointestinal haemorrhage, and jaundice. Common causes for haemobilia are iatrogenic causes secondary to hepatobiliary system instrumentation and trauma. Management of patients with haemodynamic significant haemobilia is aimed at stopping bleeding, maintaining continuous flow of biliary system, and cure of the underlying aetiology. Iatrogenic haemobilia after ERCP polyethylene biliary endoprosthesis placement is extremely uncommon. Herein we present a case of iatrogenic haemobilia triggered by biliary endoprosthesis placement and was successfully managed by non-operative treatment. The management algorithm for a rational approach to haemobilia is discussed.

Angiography↗