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Biomedical subjects

S C Poh

Publications and source records attributed to S C Poh.

At least 19 recordsLinked to original sources
PubMed2002

Cardiac output increases prior to development of pulmonary edema after re-expansion of spontaneous pneumothorax.

Pulmonary edema following reexpansion of spontaneous pneumothorax is an uncommon complication. The underlying mechanism of this condition is unclear. We report the hemodynamic characteristics in a series of 7 male patients with spontaneous large (>50%) pneumothoraces of > or = 24 h and correlate the changes with reexpansion pulmonary edema (REPE). A pulmonary artery floatation catheter was inserted and hemodynamic data were obtained before therapeutic chest tube insertion, 1 h after chest tube insertion and the following day. Four (57%) patients developed REPE. There was a tendency for larger pneumothorax to develop REPE. Capillary wedge pressure did not change significantly 1 h after the insertion of chest tube in all our patients. Cardiac output increased significantly in patients who developed REPE compared to those who did not (+ 1.06 l/min vs -0.27 l/min; P = 0.03) 1 h after insertion of chest tube. One patient did not develop pulmonary edema despite having a large (> 80%) pneumothorax. His cardiac output did not rise 1 h after chest tube insertion. REPE is not an uncommon complication following chest tube drainage in patients with large and long-standing pneumothorax. The increase in cardiac output after chest tube insertion may be associated with subsequent development of REPE.

Adult↗
PubMed2001

Diffuse panbronchiolitis--a case report.

Diffuse panbronchiolitis (DPB) is a chronic progressive obstructive disease of the airways. Of unknown aetiology, it is responsive to macrolide therapy. Although not uncommon among the Japanese, it is rare in other parts of the world. We report a case of DPB in a Chinese patient in Singapore.

Anti-Bacterial Agents↗
PubMed1998

Persistent air-leak in spontaneous pneumothorax--clinical course and outcome.

Persistent air-leak in patients with spontaneous pneumothorax (SP) is not uncommon and may present a management dilemma in those who are unfit or unwilling for surgery. Video-assisted thoracoscopic surgery (VATS) has been advocated in the management of patients with broncho-pleural fistulae (air-leak persisting beyond 7 days): however the optimum time for surgical intervention remains unclear. We reviewed the records of 130 episodes of SP in 115 patients over a 2-year period to determine clinical course and outcome, particularly with respect to duration of air-leak. There were 90 first episodes and 40 recurrent episodes. Eighty-one episodes (62%) occurred in patients with underlying lung disease (secondary pneumothorax). Initial management consisted of chest-tube drainage in 104 episodes (80%) occurring in 90 patients, percutaneous needle aspiration in five patients (4%) and observation in 21 episodes (16%) in 20 patients. In the group treated with chest-tube drainage, there was spontaneous resolution of air leak and lung re-expansion in 90 episodes (87%). The overall incidence of broncho-pleural fistula was 34.6%. In the primary SP group. 75% of air-leaks ceased by 7 days and 100% by 15 days. In the secondary SP group, 61% of air-leaks resolved by 7 days and 79% by 14 days, after which time resolution of air-leak proceeded at a much slower rate. Five patients underwent surgery while nine patients were discharged with residual pneumothoraces. There were no major complications or mortality. Based on our findings, we advocate surgery for patients with air-leak persisting beyond 14 days, while favouring a conservative approach before this time, as the majority of air-leaks (especially in patients with primary pneumothorax) would resolve by 14 days.

Adult↗
PubMed1998

Effect of oxygen on breathing irregularities during haemodialysis in patients with chronic uraemia.

Hypoxaemia and breathing irregularities have been shown to occur during haemodialysis in patients with chronic renal failure. This study examined the role of hypoxia in the genesis of the irregular breathing during haemodialysis. The ventilatory patterns using respiratory inductance plethysmography and arterial blood gases were studied in seven males with chronic renal failure on long-term haemodialysis. The study was carried out before and during dialysis on one day without (D1) and another day with intranasal oxygen at 4 L x min(-1) (D2). On D1, mean (SD) arterial oxygen tension (Pa,O2) fell 1.9 (0.9) kPa (p<0.001) and mean minute ventilation (V'E) fell 1.9 (1.1) L x min(-1) (p<0.01) during dialysis. The arterial carbon dioxide tension (Pa,CO2) did not show a significant decrease (4.7 (0.2) kPa before and 4.6 (0.2) kPa during dialysis). Cumulative number of apnoeas was 64 and the coefficients of variation (COV) of respiratory frequency (fR) and tidal volume (VT) were 29.6 (11.9) and 38.2 (11.9)%, respectively. On D2, mean Pa,O2 remained stable (20.4 (4.1) kPa before, 21.3 (4.1) kPa during dialysis). There was no significant change in mean V'E (6.4 (0.9) L x min(-1) before, 5.5 (0.5) L x min(-1) during dialysis). Pa,CO2 decrease was not significant but the fall was greater (4.8 (0.1) kPa before, 45 (0.5) kPa during dialysis). Cumulative number of apnoeas was 94 and the COVs offR and VT were 35.8 (5.1) and 40.5 (11.3)%, respectively. Oxygen administration did not significantly affect the haemodialysis-induced changes in ventilation and breathing pattern, despite a significant protective effect from the fall in arterial oxygen tension. It was concluded that the fall in arterial oxygen tension is not the main determinant of breathing irregularities during haemodialysis.

Adult↗
PubMed1998

The obstructive sleep apnoea syndrome--experience of a referral centre.

OBJECTIVE: The aims of this study were: (i) to document the presence and severity of obstructive sleep apnoea (OSA) in patients who complained of heavy snoring and other symptoms suggestive of the OSA syndrome; (ii) to examine the correlation between the clinical and polygraphic findings, and (iii) to document the efficacy and compliance of nasal continuous positive airway pressure (CPAP) among these Asian snorers with OSA. METHODS: We analysed our clinical and nocturnal polysomnographic data between January 1986 and December 1995 for physician-referred patients who had complained of snoring and other symptoms suggestive of OSA. RESULTS: A total of 277 diagnostic studies were performed of which 145 (52%) were positive to OSA. For studies performed in the last 2 years (n = 125), 72 of the 125 were positive for OSA. Anthropometric data was not discriminative between the OSA positive snorers and the OSA negative snorers. We found that hypertension and choking were the most significantly related to OSA, conferring a 7 and 4 times relative risk respectively. Nasal CPAP eliminated snoring, apnoeas and oxygen desaturations completely in almost all cases and there were only minor mask-related side effects. CONCLUSION: OSA may not be uncommon among Asian snorers. Of the major traits for OSA risk among our local population, a history of hypertension and reports of nocturnal choking were the most significantly related. We have also shown that nasal CPAP is safe and effective among our local snorers and should be considered a first-line treatment for OSA.

Adult↗
PubMed1996

Transdiaphragmatic pressure in young adult Singaporean subjects--normal values and a comparison between different respiratory manoeuvres.

BACKGROUND: Most published normal values for transdiaphragmatic pressure (Pdi) have been from Caucasian subjects and there is no universal agreement regarding the most appropriate manoeuvre for assessing Pdi. AIMS: The aims of our study were to obtain normal values and to compare the different manoeuvres used to assess Pdi in normal young Singaporean adults. METHODS: Twenty-four normal subjects (23 Chinese, one Indian) were studied by measuring Pdi during maximal sniffs from functional residual capacity (sniff Pdi), maximal inspiration to total lung capacity (Pdi TLC) and maximal static inspiratory efforts from residual volume (Pdi PImax). RESULTS: Mean values +/- SD for sniff Pdi, Pdi TLC and Pdi PImax were 101.8 +/- 31.7, 46.8 +/- 26.4 and 83.5 +/- 35.5 cm H2O respectively. Sniff Pdi was significantly higher than Pdi TLC (p < 0.001) and Pdi PImax (p = 0.005). Pdi PImax was significantly higher than Pdi TLC (p < 0.001). Males had significantly higher values for sniff Pdi (p = 0.026) and Pdi PImax (p = 0.022) than females. There was a significant correlation between the different methods of recording Pdi. Sniff Pdi had the highest values, least between- and within-subject variation and most consistent pattern of respiratory muscle recruitment with the lowest proportion of negative gastric pressure (Pg) values (p < 0.001). CONCLUSIONS: Therefore, sniff Pdi may be better than Pdi TLC and Pdi PImax in assessing diaphragm function. Also, our subjects seemed to have lower sniff Pdi and Pdi PImax, and higher Pdi TLC compared with Caucasian subjects.

Adult↗
PubMed1996

Department audit of inpatient management of asthma.

Rising asthma morbidity and mortality worldwide has prompted the recommendation of guidelines for its management. There has also been recent interest in the role of medical audit in assessing the effectiveness of guidelines, and in identifying deficiencies in clinical practice. We disseminated guidelines for the inpatient management of asthma to our department in March 1994, and subsequently performed a criterion-based audit in which we measured our performance in fulfilling various criteria deemed essential for good asthma management. Three periods in time were audited: a five-week period in March/April 1993 before the existence of guidelines (n = 22), the same period in March/April 1994 (n = 27), and the month of August 1994 (n = 17). The introduction of guidelines resulted in definite improvement in history-taking, physical examination, management, review, monitoring and patient fulfillment of pre-discharge criteria. Specific deficiencies identified were underuse of peak flow measurements, which improved after guidelines; and under prescription of oxygen, which persisted despite the guidelines. No difference was noted in terms of the quality outcome indicators of length of hospital stay, complications of procedures, hospital incidents, morbidity, mortality or visits to the A & E. There was, however, an encouraging drop (although not statistically significant) in the one-month readmission rate from 13.6% in 1993, to 7.4% and 5.9% in 1994, after the introduction of guidelines.

Adolescent↗
PubMed1995

Lung elastic recoil in normal young adult Chinese compared with Caucasians.

Chinese people have smaller total lung capacity (TLC) compared with Caucasians of similar age, sex and height. One possible reason would be a higher lung elastic recoil in Chinese. Most published values for lung elastic recoil viz static lung compliance (CLst), shape constant K, and maximal static transpulmonary pressure (PLmax) have been from Caucasian subjects. The aim of our study was to obtain values for lung elastic recoil in normal young adult Chinese subjects. Static expiratory pressure-volume (P-V) curves were studied in 22 healthy Chinese subjects (12 males and 10 females). The P-V curve was fitted using an iterative least mean squares regression on a computer, according to an exponential equation: V = A-Be-KP, where V is lung volume, P is transpulmonary pressure, and A, B and K are constants. Mean values +/- SD for K, CLst and PLmax were 0.12 +/- 0.04, 230 +/- 103 ml.cmH2O-1 and 27.5 +/- 7.5 cmH2O, respectively. The values of CLst and K were similar to that of normal Caucasian subjects, whereas values of PLmax were lower. We attributed the lower PLmax partly to weaker inspiratory muscles in Chinese compared with Caucasians. We conclude that lung elastic recoil in normal young adult Chinese is similar to that of healthy young adult Caucasians. Hence, lung elasticity is unlikely to explain the racial differences in static lung volumes.

Adult↗
PubMed1995

Evaluation of the efficacy of sequential intravenous-oral administration of pefloxacin in community-acquired lower respiratory tract infections in patients with underlying conditions.

We studied the efficacy of sequential intravenous-oral pefloxacin therapy in community-acquired lower respiratory tract infection in 24 patients with one or more underlying conditions. Twenty-eight patients were enrolled into the study but only 24 patients were evaluated. There were 16 males and 8 females with a mean age of 66.9 +/- 11.2 years (mean +/- SD, range 46 to 87 years). The underlying conditions present were bronchiectasis, chronic obstructive lung disease and diabetes mellitus. Patients who were older than 70 years but without any underlying condition were also enrolled. All received 4 days of intravenous pefloxacin 400 mg twice a day followed by oral pefloxacin 400 mg twice a day for another 10 days. Assessment of success was based on clinical, microbiological and radiological improvement. Pefloxacin produced 79.2% clinical cure rate. Another 8.3% showed improvement. Pefloxacin was well tolerated. There were few adverse effects and none of the patients required a change of antibiotic. Pefloxacin was an effective and well tolerated treatment for respiratory tract infection and had the advantage of broad in-vitro antibacterial activity, twice daily dosing and sequential availability in an intravenous and oral formulation.

Administration, Oral↗
PubMed1994

Case of occupational asthma due to glue containing cyanoacrylate.

Cyanoacrylates are a rare cause of occupational asthma, there being only six cases reported previously. High humidity has been implicated to be protective in the pathogenesis of the asthma. This is a case report of occupational asthma due to cyanoacrylate glue after working three years in a factory manufacturing doors. Diagnosis was made by history, serial peak flow measurements on and off work and specific inhalation challenge which elicited a delayed bronchoconstrictive response. An unusual feature of this case was the positive reaction to cyanoacrylate despite the high ambient humidity in Singapore.

Adhesives↗
PubMed1994

A case of occupational asthma due to barley grain dust.

We report a case of occupational asthma due to barley grain dust, species Hordeum Vulgare L, in a 32-year-old storeman of a trading company's department that dealt with packaging of flour, barley and peanuts. He developed immediate symptoms of sneezing, cough and dyspnoea on exposure to barley only. These symptoms showed work relationship. He became asymptomatic after his transfer to another department dealing with sales only. Bronchial provocation testing to the barley confirmed the diagnosis.

Adult↗
PubMed1994

A case of late dumping syndrome.

We report a case of late dumping syndrome in a 49-year-old lady who had partial gastrectomy for bleeding peptic ulcer 11 years ago. She presented with unexplained syncopal attacks which did not have any apparent relationship to meal or posture. An unusual reaction to oral glucose tolerance test ordered by her gynaecologist who was seeing her for uterine fibroid led to the diagnosis. Late dumping syndrome was confirmed by a repeat oral glucose tolerance test. At the second hour of the test, she developed hypoglycaemic coma with a blood glucose level of 50 mg/dL and a hypocount of 47 mg/dL. She regained full recovery after dextrose infusion which raised the hypocount to 123 mg/dL. The dizzy spells and syncopal attacks disappeared with dietary adjustment.

Diagnosis, Differential↗
PubMed1993

Epidemiology of sudden unexpected death syndrome among Thai migrant workers in Singapore.

A total of 235 cases of sudden unexpected death syndrome (SUDS) among apparently healthy male Thai migrant workers in Singapore were reported between 1982 and 1990. Most of the deaths occurred during sleep and 13% were not sleep-related. The median age at the time of death was 33 years and the median interval between arrival and death was 8 months. These deaths occurred singly and sporadically throughout the year. Post-mortem examination revealed few abnormal findings except for haemorrhagic congestion or oedema of the lungs. There were moderate to severe intra-alveolar haemorrhages with some evidence of myocarditis or pneumonitis. Preliminary findings of serial sections of the hearts indicate evidence of anomalies in the cardiac conduction system. Epidemiological investigations showed that a family history of similar deaths and serological evidence of current or recent infection with Pseudomonas pseudomallei were significantly associated with SUDS. Extensive biochemical and toxicological investigations were inconclusive. There was no evidence of chronic deficiency in thiamine or potassium among the healthy Thai workers living and working in the same conditions as the cases, and no significant abnormalities were detected on electrocardiographic examination. As these migrant workers experienced various psychosocial problems which could stem from maladjustment to an urban environment, separation from the family, burden of debts and long hours of work, stress could be a precipitating factor for SUDS.

Adult↗
PubMed1993

Pulmonary function in healthy Chinese, Malay and Indian adults in Singapore.

Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEFR), single-breath diffusion capacity measurements (effective alveolar volume (VA), carbon monoxide transfer factor (DLCO) and transfer coefficient (KCO)) were determined in 452 healthy Singaporean adults (277 males and 175 females) aged 20-70 years. The ratio of Chinese, Malay and Indian subjects was 5:2:3 in both sexes. Age, height and weight in the males were all significantly correlated with FEV1, FVC, DLCO, VA and PEFR. However, for females, only age and height were significantly correlated with the studied lung function parameters. Significant ethnic differences were observed for most of the pulmonary functions (except KCO and PEFR) among the Chinese, Malays and Indians for both males and females. The predicted FEV1 and FVC values (specific age and height) for both sexes were highest among the Chinese followed by the Malays than Indians, in that order. Regression equations, with age and height as independent variables, were derived for males and females in each ethnic group to predict normal pulmonary function for the Singapore Chinese, Malay and Indian populations. The predicted values of various pulmonary function measurements obtained from these regression equations for subjects of specified age (30 years) and height (165 cm for men, 155 cm for women) were compared with those reported in other studies. Differences were observed among the different races.

Adult↗
PubMed1993

The effect of oral midazolam and diazepam on respiration in normal subjects.

Benzodiazepine have been shown to suppress ventilatory responses to hyperoxic hypercapnia (HCVR) and isocapnic HVR when taken parenterally. Most patients would, however, prefer to take an oral rather than parenteral preparation but the effect of oral benzodiazepine on these ventilatory responses has not been well studied. We therefore studied the effect of oral midazolam (7.5 mg) and diazepam (5 mg) both given orally on resting ventilation and respiratory drive, as assessed by HCVR and HVR. Flumazenil, a specific benzodiazepine antagonist, was administered intravenously to reverse the effect. A mental alertness-drowsiness index in five grades, from 1 (awake and alert) to 5 (asleep), was used to assess the sedation effect. Six normal male subjects, (aged 31 +/- 1.6 yrs) (mean +/- SD), participated in the study. Mean resting ventilation, and ventilatory response to HCVR and HVR were not significantly altered by these drugs when taken orally. Flumazenil also had not significant effect on HCVR and HVR. However the mental alertness-drowsiness index rose from 1 to 2.83 with oral midazolam and reversed to 1.25 with flumazenil. Similarly, this index increased from 1 to 2.25 after oral diazepam and reversed to 1.42 after flumazenil. In conclusion, we found that even though oral midazolam and diazepam produced a significant sedation effect, which was reversed with flumazenil, the drugs had no effect on ventilation at rest and the ventilatory responses to hypoxia and hypercapnia.

Administration, Oral↗
PubMed1992

A case of primary diffuse tracheobronchial amyloidosis treated by laser therapy.

We report a case of primary diffuse tracheobronchial amyloidosis in a 72-year-old lady who presented with a long history of recurrent cough, dyspnoea, wheezing, haemoptysis and chest infection. She was treated successfully with three sessions of laser therapy. There were improvements in both clinical symptoms and measurements of airway obstruction. Bronchodilators and oral prednisolone were not required after treatment.

Amyloidosis↗