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Biomedical subjects

K S Fung

Publications and source records attributed to K S Fung.

At least 19 recordsLinked to original sources

Sodium ramping reduces hypotension and symptoms during haemodialysis.

OBJECTIVES: To evaluate the effectiveness of sodium ramping (profiling) in reducing hypotensive episodes and symptoms during haemodialysis. DESIGN: Prospective study. SETTING: Regional hospital, Hong Kong. PATIENTS: Thirteen patients who experienced frequent episodes of hypotension and/or symptoms such as cramps, dizziness, chest pain, nausea, vomiting, and headache during haemodialysis in the preceding 4 weeks. INTERVENTIONS: Each patient was switched from standard haemodialysis with a constant dialysate sodium concentration of 135 to 140 mmol/L to a ramped sodium haemodialysis for a period of 4 weeks. During this time the dialysate sodium concentration was ramped linearly downwards from 150 mmol/L at the beginning of dialysis to 140 mmol/L at the end of dialysis. MAIN OUTCOME MEASURES: Intradialytic hypotensive episodes, intradialytic symptoms, nursing interventions, systolic and diastolic blood pressures, and interdialytic weight gain. RESULTS: A total of 248 haemodialysis sessions undertaken by 13 patients were analysed. Switching from constant sodium haemodialysis to ramped sodium haemodialysis resulted in a significant reduction in the number of intradialytic hypotensive episodes from 5.8 (standard deviation, 6.4) to 2.2 (3.3) [P<0.05], the total number of intradialytic symptoms from 7.1 (3.4) to 0.9 (1.3) [P<0.01], and nursing interventions from 11.3 (6.3) to 1.7 (3.9) [P<0.01]. Post-dialysis systolic and diastolic blood pressures were higher during ramped sodium haemodialysis compared with constant sodium haemodialysis (systolic blood pressure, 139 [standard deviation, 23] vs 133 [22] mm Hg, P<0.001; diastolic blood pressure, 77 [11] vs 74 [13] mm Hg, P<0.01), and there was a trend towards a smaller drop in blood pressure after dialysis. The interdialytic weight gain with sodium ramping haemodialysis was greater compared with constant sodium haemodialysis (3.1 [standard deviation, 1.0] vs 2.7 [1.1] kg, P<0.001). CONCLUSION: Sodium ramping during haemodialysis effectively reduces hypotensive episodes and intradialytic symptoms. Post-dialysis blood pressure is better maintained. A side-effect of sodium ramping is a greater interdialytic weight gain.

Blood Pressure↗

Minimal change disease following exposure to mercury-containing skin lightening cream.

A 34-year-old woman developed nephrotic syndrome after using a skin lightening cream that contained an extremely high level of mercury. Blood and urine mercury levels were elevated and a renal biopsy revealed minimal change disease. Membranous nephropathy was excluded using immunofluorescence and electron microscopy. Her proteinuria remitted 9 months after she stopped using the cosmetic cream. This is the first reported case in the English literature of proven minimal change disease secondary to mercury exposure. It is important that mercury poisoning due to cosmetic cream is considered in the differential diagnoses for any woman who presents with nephrotic syndrome.

Adult↗

Randomised controlled study of oral erythromycin for treatment of gastrointestinal dysmotility in preterm infants.

AIM: To evaluate the effectiveness of oral erythromycin as a prokinetic agent for the treatment of moderately severe gastrointestinal dysmotility in preterm very low birthweight infants. METHODS: A prospective, double blind, randomised, placebo controlled study in a tertiary referral centre of a university teaching hospital was conducted on 56 preterm infants (< 1500 g) consecutively admitted to the neonatal unit. The infants were randomly allocated by minimisation to receive oral erythromycin (12.5 mg/kg, every six hours for 14 days) or an equivalent volume of placebo solution (normal saline) if they received less than half the total daily fluid intake or less than 75 ml/kg/day of milk feeds by the enteral route on day 14 of life. The times taken to establish half, three quarters, and full enteral feeding after the drug treatment were compared between the two groups. Potential adverse effects of oral erythromycin and complications associated with parenteral nutrition were assessed as secondary outcomes. RESULTS: Twenty seven and 29 infants received oral erythromycin and placebo solution respectively. The times taken to establish half, three quarters, and full enteral feeding after the drug treatment were significantly shorter in the group receiving oral erythromycin than in those receiving the placebo (p < 0.05, p < 0.05 and p < 0.0001 respectively). There was also a trend suggesting that more infants with prolonged feed intolerance developed cholestatic jaundice in the placebo than in the oral erythromycin group (10 v 5 infants). None of the infants receiving oral erythromycin developed cardiac dysrhythmia, pyloric stenosis, or septicaemia caused by multiresistant organisms. CONCLUSIONS: Oral erythromycin is effective in facilitating enteral feeding in preterm very low birthweight infants with moderately severe gastrointestinal dysmotility. Treated infants can achieve full enteral feeding 10 days earlier, and this may result in a substantial saving on hyperalimentation. However, until the safety of erythromycin has been confirmed in preterm infants, this treatment modality should remain experimental. Prophylactic or routine use of this medication for treatment of mild cases of gastrointestinal dysmotility is probably not warranted at this stage.

Double-Blind Method↗

Effect of low molecular weight heparin on bone metabolism and hyperlipidemia in patients on maintenance hemodialysis.

The effect of low molecular weight heparin (LMWH) on serum lipid profile in hemodialysis remains controversial and its effect on bone metabolism has not been studied. A crossover study was conducted in 40 patients on stable hemodialysis using unfractionated heparin (UFH) for more than 24 months. These patients were then treated with a LMWH (nadroparin-Ca) for 8 months during hemodialysis and subsequently switched back to UFH for 12 months. Serum lipid profile, biochemical markers for bone metabolism, and bone densitometry (BMD) were monitored at four-month intervals while all medications remained unchanged. Cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C), lipoprotein(a) (Lp(a)), apolipoprotein B (Apo B) were raised in 35%, 29%, 12%, 24% and 24% of patients respectively. High-density lipoprotein-cholesterol (HDL-C) and apolipoprotein A1 (Apo A-1) were reduced in 47% and 9% of patients. Bone-specific alkaline phosphatase (BALP) and intact osteocalcin (OSC), both reflecting osteoblastic activity, were raised in 65% and 94% of patients. Tartrate-resistant acid phosphatase (TRACP) reflecting osteoclastic activity and parathyroid hormone (PTH) were elevated in 35% and 88% of patients. Following LMWH treatment, TC, Tg, Lp(a) and Apo B were reduced by 7%, 30%, 21% and 10% respectively (p<0.05 or <0.01) while Apo A-1 were raised by 7% (p<0.01). Simultaneously, TRACP was reduced by 13% (p<0.05). These biochemical changes were detected soon after 4 months of LMWH administration. Although BMD values in our patients were lower than those of age-matched normal subjects, significant changes were not observed with LMWH treatment. After switching back to UFH for hemodialysis, these biochemical indices reverted to previous values during UFH treatment with a significant higher level in TC and Apo B while serum Apo A-1 remained elevated. Our study suggests LMWH may partially alleviate hyperlipidemia and, perhaps, osteoporosis associated with UFH administration in patients on maintenance hemodialysis.

Adult↗

A tracing evoked potential estimator.

The paper presents an adaptive Gaussian radial basis function neural network (RBFNN) for rapid estimation of evoked potential (EP). Usually, a recorded EP is severely contaminated by background ongoing activities of the brain. Many approaches have been reported to enhance the signal-to-noise ratio (SNR) of the recorded signal. However, non-linear methods are seldom explored due to their complexity and the fact that the non-linear characteristics of the signal are generally hard to determine. An RBFNN possesses built-in non-linear activation functions that enable the neural network to learn any function mapping. An RBFNN was carefully designed to model the EP signal. It has the advantage of being linear-in-parameter, thus a conventional adaptive method can efficiently estimate its parameters. The proposed algorithm is simple so that its convergence behaviour and performance in signal-to-noise ratio (SNR) improvement can be mathematically derived. A series of experiments carried out on simulated and human test responses confirmed the superior performance of the method. In a simulation experiment, an RBFNN having 15 hidden nodes was trained to approximate human visual EP (VEP). For detecting human brain stem auditory EP (BAEP), the approach (40 hidden nodes and convergence rate = 0.005) speeded up the estimation remarkably by using only 80 ensembles to achieve a result comparable to that obtained by averaging 1000 ensembles.

Electroencephalography↗

Comparison of double-bag and Y-set disconnect systems in continuous ambulatory peritoneal dialysis: a randomized prospective multicenter study.

We performed a multicenter, single-blinded, prospective randomized study on the use of a double-bag disconnect system (B) versus a Y-set disconnect system (Y). The peritonitis rate, exit site infection, clinical outcome, and patients' acceptance to the procedure were assessed. A total of 120 new end-stage renal failure patients of three regional hospitals were randomized: 60 each to the B and the Y systems. The results of 60 patients on the B system and 51 on the Y system were analyzable. They were followed up for a median of 16 months. Peritonitis rates for the B and the Y systems were 33.5 and 29.4 patient-months per episode, respectively. Exit site infection rates for the B and Y systems were 17.4 and 16.0 patient-months per episode, respectively. Four catheters were removed in each group. Patients on the B system were hospitalized for 2.1 days per patient per year related to peritonitis and exit site infection, and those on the Y system were hospitalized for 1.2 days. There was no significant difference between the B and Y systems in the incidences of peritonitis (all causes and those due to coagulase-negative staphylococci), exit site infection, and in hospitalization days. However, there was a higher percentage of gram-positive infections in the Y system (52%) than in the B system (32%) and a lower percentage of gram-negative infections in the Y system (16%) than in the B system (32%). Patients on the B system had a better acceptance of the procedure than patients on the Y system, as assessed by a six-item, 10-point questionnaire (total score, 43.1 +/- 10.2 v 37.6 +/- 9.4; P < 0.005 at 1 month; 44.6 +/- 9.1 v 39.8 +/- 8.6; P < 0.01 at 6 months). From this study, it is concluded that the B and Y systems are similar in the incidences of peritonitis and exit site infection, although the B system is better accepted by patients. This is probably the first multicenter randomized study comparing the double-bag and Y-set disconnect system using only new patients who had never used other systems of continuous ambulatory peritoneal dialysis.

Adult↗

Epidemiology of respiratory syncytial virus infection among paediatric patients in Hong Kong: seasonality and disease impact.

In a 5-year retrospective survey of respiratory syncytial virus (RSV) infections among hospitalized children, 1340 cases were identified of which, 98.4% were children < 5 years old with a male:female ratio of 1.5: 1. Most cases occurred from April to September showing a significant positive correlation with temperature and relative humidity. Community-acquired infections accounted for 92.5% of the cases with a mean hospital stay of 5 days. The estimated annual incidence of RSV infection requiring hospitalization was 2.5/1000 children < 5 years old with a mortality of 0.15% among hospitalized cases. On average, 248 children were admitted each year to the 1400-bed acute regional hospital accounting for an expenditure of HK S1.94 ((approximately US +/-0.25) million for hospitalization costs which equates to an annual cost in excess of HK $6.67 (approximately US $0.86) million for the whole of Hong Kong. An RSV vaccine should be a priority.

Child, Preschool↗

Rotavirus infection in Hong Kong: epidemiology and estimates of disease burden.

Rotavirus gastroenteritis should soon be a vaccine-preventable disease. In a 10-year survey of rotavirus gastroenteritis conducted at the Prince of Wales Hospital (PWH), 2281 cases were detected of which 2213 (97%) occurred in children < 5 years old. A consistent epidemic occurred each winter during the months of December and January. Of all laboratory-confirmed cases, 78% were community-acquired with a mean hospital stay of 4.7 days. The estimated incidence of rotavirus-attributed hospitalization was 2/1000 children < 5 years old. Over the 10 years, rotavirus was responsible for one death, and contributory to three other deaths. On average each year, 195 children < 5 years old were hospitalized for a total of 917 days in PWH, accounting for an estimated expenditure of HK$2.8 (approximately US$0.4) million on hospitalization costs. The annual financial burden for rotavirus gastroenteritis for the whole of Hong Kong could be in excess of HK$9.6 (approximately US$1.2) million.

Age Factors↗

Self-inflicted bacteraemia and fungaemia in Vietnamese migrants.

From early 1993, we received a number of blood cultures, all from Vietnamese inmates of the Whitehead Detention Centre, the biggest detention camp in Hong Kong, which grew unusual organisms. Upon follow-up, the majority of the patients were found to abscond from the hospital a few days after having been admitted with a clinical picture of septic shock. During the period from March 1993 to late 1994, we noted a total of 25 positive blood cultures from 21 previously healthy Vietnamese migrants with this syndrome. The mean age was 27.8 years and 20 were males. The organisms isolated from the blood cultures were of low pathogenicity such as Saccharomyces cerevisiae, Trichosporon spp., Baciflus spp. and Micrococcus spp. Fourteen of the patients complained of abdominal pain and 3 others had apical pneumothoraces. Eighteen had shock requiring resuscitation. Multiple puncture or needle marks were found in 11 patients, mainly involving the lower limbs. One patient admitted inducing illness by self-injection, and it was suspected that all these infections were self-inflicted. The range of hospitalization was 1-13 days (mean 3.05 days). Eighteen of the 21 patients absconded.

Adolescent↗

Rapid emergence of penicillin-resistant pneumococci in Hong Kong.

The prevalence of penicillin resistance in Streptococcus pneumoniae isolated at the Prince of Wales Hospital, Hong Kong, rose from 6.6% of sputum isolates in the first quarter of 1993 to 55.8% of isolates in the second quarter of 1995. Most of the isolates were also resistant to co-trimoxazole, tetracycline, choramphenicol and erythromycin. Type 19F was the most common capsular type in 1993-1994, comprising 40.0% of typed isolates in this period. Type 23F emerged in 1995 as the predominant type, making up 62.2% of typed isolates in the first 2 quarters of 1995. A high population density and excessive community use of antibiotics are likely to be factors promoting the rapid emergence of multiply-resistant pneumococci in Hong Kong.

Drug Resistance, Microbial↗

Visual evoked potential enhancement by an artificial neural network filter.

The application of an artificial neural network filter (ANNF) to estimate the visual evoked potential (VEP) is presented. VEP is the gross electrical response of the brain to visual stimuli. Due to the low SNR, it is difficult to extract response from individual stimulus trials. The ANNF we used estimates the deterministic component of the signal and removes the noise uncorrelated with the stimulus, even when the noise is colored. The ANNF is trained through back-error propagation with a data set consisting of a training signal and a target signal. The training signal is the raw VEP from a single trial having a SNR of about -5 dB, while the target signal has a higher SNR which is achieved by ensemble averaging 100 stimulus trials. Simulated signals were generated to test the performance of the ANNF. Results show that the ANNF could greatly enhance the SNR of the VEP to single visual stimulus. Thus the total number of ensembles is reduced. In clinical applications, the traditional ensemble averaging method requires a hundred ensembles to determine the VEP. When ANNF is used, about 20 ensembles are sufficient for the same purpose.

Adolescent↗

Development and validation of a claims based index for adjusting for risk of mortality: the case of acute myocardial infarction.

We developed a comorbidity index on a cohort of 162,699 Medicare beneficiaries who had an acute myocardial infarction (AMI) in 1987 and validate it on two national cohorts: (1) a cohort of 164,427 Medicare beneficiaries who had an AMI in 1988 and (2) a cohort of 10,466 patients admitted to Veterans Administration Hospitals (VAH) for AMI in 1988-1991. The impact of each sensitivity was expressed as; (1) the risk of mortality for those with the comorbidity, (2) the adjustment to the log odds for 2 year mortality and (3) the age-based likelihood of 2 year mortality. Models were validated by calculated the area under an ROC curve obtained by fitting a logistic regression model to each validation population. The two year mortality rate for 30-day survivors was approximately 30% in each of the 3 cohorts. The 5 most prevlent comorbidities coded in the developmental cohort were heart failure (34%), chronic angina (27%), minor arrythmias (25%) and uncomplicated hypertension (18%). Cancer was the most powerful predictor of 2 year mortality, impacting mortality the same as a 18.3 year age increase. Saturation (having all secondary diagnoses in the discharge summary filled) resulted in a 9.2 year age increase. Validation in the 1988 Medicare and in the Veterans Administration Hospitals cohorts resulted in areas of 73% and 72% under the respective ROC curves. Our methods can serve as a prototype for others wishing to assess comorbidity in other targeted subgroups.

Aged↗

Cutaneous protothecosis: report of a case in Hong Kong.

We report a patient who presented with recalcitrant ulcerated papules and plaques on both legs. Histopathology revealed protothecosis, and subsequent culture of the lesions grew Prototheca wickerhamii. Gradual resolution of the ulcers occurred on treatment with itraconazole.

Aged↗

The antimicrobial activity and beta-lactamase stability of cefpirome, a new fourth-generation cephalosporin in comparison with other agents.

The antimicrobial activity of cefpirome was compared with amoxycillin/clavulanic acid, ampicillin/sulbactam, cefuroxime, ceftazidime, gentamicin and amikacin against 743 non-duplicate clinical isolates. MIC50 and MIC90 showed that the antibiotic was active against both Gram-negative and Gram-positive organisms. Cefpirome was highly active against most of the Enterobacteriaceae, including indole-positive Proteus spp., Aeromonas spp. (MIC < or = 1 mg/L) and Salmonella spp. (MIC < or = 0.5 mg/L). Neisseria gonorrhoeae and Haemophilus influenzae (including beta-lactamase producers) were all susceptible, with MIC less than 0.5 and 0.25 mg/L respectively. Cefpirome was more active than cefuroxime and ceftazidime against Campylobacter spp. (MIC < or = 2 mg/L), but less active than ceftazidime against Pseudomonas aeruginosa. Cefpirome was active against Streptococcus pneumoniae. Streptococcus bovis and coagulase-negative staphylococci (MIC < or = 0.5 mg/L) and methicillin-sensitive Staphylococcus aureus (MIC < or = 2 mg/L). Methicillin-resistant S. aureus, Gram-positive and Gram-negative anaerobes were resistant to cefpirome. The stability of cefpirome to TEM-1, TEM-2, PSE-1, SHV-1 and the chromosomal-mediated P99 and K-1 beta-lactamases was comparable to ceftazidime.

Acinetobacter↗

Necrotizing fasciitis of the foot caused by an unusual organism, Vibrio vulnificus.

In modern medicine, there are very few infectious disease processes occurring in the foot that can cause death within 48 hr. and have an overall mortality rate of 50% despite appropriate antibiotic and surgical treatment. Such a condition must be regarded as being potentially deadly. The authors report a case of necrotizing fasciitis of the left foot resulting from an unusual organism of Vibrio vulnificus.

Debridement↗