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Biomedical subjects

T E Oh

Publications and source records attributed to T E Oh.

At least 55 records · Page 3Linked to original sources
PubMed1993

Verification of the Acute Physiology and Chronic Health Evaluation scoring system in a Hong Kong intensive care unit.

OBJECTIVES: To validate the Acute Physiology and Chronic Health Evaluation (APACHE II) severity of illness scoring system in Chinese patients in a multidisciplinary intensive care unit (ICU) in Hong Kong. To audit the service and utilization of an ICU with a low ICU to hospital bed ratio. DESIGN: Prospective data collection and review. SETTING: A 12-bed multidisciplinary ICU within a 1,430-bed tertiary care university hospital. PATIENTS: Data from 1,573 of 1,814 consecutive patients admitted to the ICU from May 1988 to November 1990 were studied. The patients were all Chinese. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The patients' clinical details and APACHE II scores were recorded on day 2 of admission and reviewed at hospital discharge or after death. The APACHE II scores, risk of death values, age, and length of ICU stay between survivors and nonsurvivors were compared by two-sample t-tests. Relationships between mortality and APACHE II score, risk of death, and results from previous studies were investigated using the Pearson product-moment coefficient and regression analysis. Predictive capacity of risk of death was assessed by receiver operating characteristic curve analysis. The hospital mortality rate for study patients was 36%. Survivors were younger, had shorter ICU stays, lower APACHE scores, and lower risk of death values than nonsurvivors (p < .001). There was close correlation (r2 = .81, .77, and .76 for all patients, operative group, nonoperative group, respectively) between APACHE II scores and predicted risk of death values. Risk of death was an accurate group predictor of death in all patients and in separate operative and nonoperative groups. Areas under the receiver operating characteristic curves were 0.89 (all patients), 0.85 (operative), and 0.88 (nonoperative). Neither the Apache II scores nor risk of death scores were sufficiently accurate to predict outcome of individual patients. There was close concordance between observed and predicted mortality of patient groups. Mortality ratio was 0.97 (all patients), 0.89 (operative group), and 1.02 (nonoperative group). Chronological age, per se, was not a good predictor of mortality. The audit of the ICU service showed a short length (4.2 days) of ICU stay and high bed occupancy (80%). Subgroups of low-risk, postoperative patients with good outcomes and poor-risk patients admitted after cardiopulmonary arrest with a high mortality rate were identified. CONCLUSIONS: The APACHE II scoring system was an accurate predictor of group outcome in a Chinese population, making it suitable for comparisons between countries. Application of the APACHE II scoring system in a clinical audit facilitates critical appraisal of an ICU service. Problems identified by the study were a shortage of ICU beds and delayed referrals of patients.

Adult↗
PubMed1993

Critical incident reporting in an anaesthetic department quality assurance programme.

The critical incident technique was introduced as an additional form of quality assurance to an anaesthetic department of a major Hong Kong teaching hospital. In one year, 125 critical incidents were reported from over 16,000 anaesthetics. The most common incidents reported concerned the airway, breathing systems, and drug administration, with inadequate checking of equipment a frequent associated factor. Human error was a factor in 80% of incidents. Critical incidents were reported for the time during which the patient was under the anaesthetist's care. The majority occurred at induction or during anaesthesia, and were reported for all surgical subspecialties. Half of the incidents were detected by the anaesthetist and one third by monitoring equipment. Although there were improvements in anaesthetic care as a consequence of increased vigilance, critical incidents still occurred. Critical incident reporting highlighted problems not otherwise covered by case and peer reviews, and complemented our quality assurance programme.

Adolescent↗
PubMed1993

Pharmacokinetic model-controlled infusion of midazolam. A prospective evaluation during general anaesthesia.

The accuracy of a computer-controlled infusion of midazolam, based on previously published pharmacokinetic parameters, was tested prospectively in 12 adult female patients undergoing general anaesthesia. Anaesthesia consisted of an initial bolus followed by an exponentially decreasing infusion of midazolam given according to body weight, fentanyl, nitrous oxide and vecuronium. Venous blood samples were taken at 15 min-intervals throughout the procedures and for 1-2 h postoperatively. The bias of the model was -5.1% (95% CI -11.3 to 1.2%) and precision 24.8% (95% CI 20.9 to 28.6%). Least squares regression analysis decreased the bias to -2.8% but did not alter precision. Retrospective fitting of an alternative set of published parameters for midazolam resulted in significant deterioration of the model. The precision was similar to that found in past studies of intravenous anaesthetic agents. Further improvement in the accuracy of midazolam infusion awaits improved understanding of the causes of pharmacokinetic variability.

Adult↗
PubMed1993

Suxamethonium myalgia: an ethnic comparison with and without pancuronium pretreatment.

The incidence of myalgia after suxamethonium was determined in 200 fit military male dental patients of European, Chinese and Nepalese descent. Half received pancuronium 1 mg and the other half received saline pretreatment on a randomised double-blind basis. The percentage incidence of postsuxamethonium myalgia after saline or pancuronium was found to be: Europeans 26%, 13%; Chinese 13%, 7%; Nepalese 20%, 14%. Although pancuronium reduced the incidence of myalgia by about 50% overall, these values were not significantly different from each other. The recovery of spontaneous ventilation following suxamethonium was quicker in the Europeans than in the Asians (p < 0.05). Pancuronium pretreatment also delayed the recovery of spontaneous ventilation and recovery from neuromuscular block (p < 0.05) but this was independent of ethnicity. The Europeans recovered from anaesthesia more quickly than the Asians. It was concluded that ethnicity affected recovery from suxamethonium and from anaesthesia but was not of clinical relevance to the incidence of myalgia in male Asians and Europeans.

Adolescent↗
PubMed1993

Anaesthesia for laparoscopic general surgery.

Laparoscopic surgery minimises postoperative morbidity. Patient benefits include reduction in postoperative pain, better cosmetic result and quicker return to normal activities. Hospital stay is shortened resulting in a reduction in overall medical cost. The intraoperative requirements of laparoscopic surgery however can lead to serious physiological changes and complications. While there is a low but definite perioperative mortality rate associated with minor gynaecologic laparoscopic procedures, laparoscopic general surgical procedures are performed on older patients and patients with acute surgical conditions and are likely to be associated with a higher incidence of perioperative complications. The major problems during laparoscopic surgery are related to the cardiopulmonary effects of pneumoperitoneum, systemic carbon dioxide absorption, extraperitoneal gas insufflation, venous gas embolism and unintentional injuries to intra-abdominal structures. An appraisal of the potential problems is essential for optimal anaesthetic care of patients undergoing laparoscopic surgery. Appropriate anaesthetic techniques and monitoring facilitate surgery and allow early detection and reduction of complications. The need for rapid recovery and short hospital stay impose additional demands on the anaesthetist for skillful practice.

Anesthesia, General↗
PubMed1992

Systemic absorption of glycine irrigation solution during endometrial ablation by transcervical endometrial resection.

OBJECTIVE: To study systemic absorption of glycine irrigation solution and its consequences during transcervical endometrial resection (TCER). DESIGN, SETTING, PATIENTS: A prospective study of 20 consecutive female patients who underwent elective TCER in a teaching hospital. METHOD: During the operation, patients were monitored with electrocardiography, automated oscillotonometry, pulse oximetry, capnography and a central venous pressure recorder. Plasma sodium and potassium levels were measured at 15-minute intervals. Blood haemoglobin concentration, serum osmolality, and plasma sodium, potassium and glycine concentrations were measured before and after surgery. RESULTS: Plasma glycine concentration increased in all patients after TCER. The highest concentration recorded was 5575 mumol/L. The increase correlated only with the maximum intraoperative decrease in plasma sodium, which was 7 mmol/L in two patients whose plasma glycine level increased by 3001 mumol/L and 5335 mumol/L. CONCLUSION: Systemic absorption of glycine irrigation solution occurred in all patients during TCER. Serial measurement of plasma sodium was necessary to detect this complication. A decrease in plasma sodium level by 7 mmol/L or more during surgery would indicate fluid absorption that could cause severe hyperglycinaemia and other potential complications.

Absorption↗
PubMed1992

Induction dose-response of propofol in unpremedicated children.

The induction dose requirements of propofol were compared in three age groups in 300 unpremedicated healthy Chinese children: group A, younger than 2 yr (n = 48); group B, 2-5 yr (n = 117); group C, 6-12 yr (n = 135). Patients in each group were allocated randomly to receive one of eight doses of propofol (1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4 and 2.6 mg kg-1). ED50 and ED95 for loss of eyelash reflex (LER) and acceptance of face mask (AFM) were determined using probit analysis. ED50 and ED95 for both LER and AFM were greatest in group A, less in B and smallest in C; ED95 (AFM) for groups A, B and C were 2.88 (2.55-3.36), 2.53 (2.31-2.86), and 2.20 (2.02-2.46) mg kg-1, respectively. This probably represented their effective induction dose. The incidence of apnoea was dose related, but not pain on injection.

Age Factors↗
PubMed1992

Effect of dobutamine on oxygen supply and uptake in healthy volunteers.

We have measured the changes in VO2 and the VO2:DO2 relationship during infusion of dobutamine in healthy volunteers. Nine healthy, adult, non-obese, male physicians were infused with an incremental infusion of dobutamine starting at 2.5 micrograms kg-1 min-1 increasing to 5.0 and then 7.5 micrograms kg-1 min-1 for 15 min each. VO2 and cardiac index were measured every five minutes. VO2I (VO2m-2) increased from a baseline of 128 (SEM 6.1) ml min-1 m-2 to 159 (8.0) ml min1 m-2 (P < 0.05) at the end of infusion with 7.5 micrograms kg-1 min-1. The corresponding changes for DO2I (DO2 m-2) were from 643 (35) ml min-1 m-2 to 1240 (142) ml min-1 m-2 (P < 0.05). The coefficient of correlation for pairs of VO2 and DO2 values, at baseline and each dobutamine infusion in individual subjects, ranged from 0.89 to 0.99 (mean 0.95, SD 0.03). Dobutamine has potent calorigenic effects; demonstration of a positive correlation between VO2 and DO2 after infusion of dobutamine does not necessarily imply an underlying tissue oxygen debt.

Adult↗
PubMed1992

A comparison of omeprazole and ranitidine for prophylaxis against aspiration pneumonitis in emergency caesarean section.

One hundred and sixty-two Chinese women undergoing emergency Caesarean section were allocated at random on admission to the labour ward to receive one of three regimens for orally administered chemoprophylaxis against acid aspiration: ranitidine 150 mg 6 hourly with sodium citrate at induction of anaesthesia, omeprazole 40 mg 12 hourly with sodium citrate, or omeprazole 40 mg 12 hourly alone. Intragastric pH and volume were measured immediately after induction of anaesthesia. Ten patients (17%) in the omeprazole-only group, three (6%) in the omeprazole and citrate group and one (2%) in the ranitidine group had an intragastric pH less than 2.5 and volume greater than 25 ml (p less than 0.05). The use of sodium citrate resulted in higher intragastric pH but larger intragastric volumes (p less than 0.05). The sodium citrate and ranitidine regimen was the most cost-effective among the three.

Cesarean Section↗
PubMed1992

Resistance and additional inspiratory work imposed by the laryngeal mask airway. A comparison with tracheal tubes.

Laryngeal mask airways and tracheal tubes were studied to determine both their resistance to constant gas flows and additional inspiratory work during simulated inspiration. Laryngeal mask airways imposed less resistance and required lower additional inspiratory work compared with the corresponding sized tracheal tubes. If inspiratory loading during anaesthesia is an important consideration, then the laryngeal mask airway may be preferable to a tracheal tube.

Airway Resistance↗
PubMed1992

Anaesthesia for bullectomy. Use of propofol, high frequency jet ventilation and extradural blockade.

A patient with a single large bulla occupying 50% of the right hemithorax was anaesthetised successfully with a combination of techniques not previously described. The technique consisted of extradural analgesia and intravenous infusion of propofol, while ventilation was maintained with high frequency jet ventilation through a single lumen tracheal tube. The advantages of this technique are a reduced risk of barotrauma, good operating conditions and good analgesia.

Anesthesia, Intravenous↗
PubMed1992

Vecuronium: an anthropometric comparison.

This study set out to determine if there was any resistance to vecuronium in Nepalese studied in Nepal compared with Nepalese, Chinese and European patients studied in Hong Kong. The four groups, each of 10 male and 10 female patients, were intubated 60 s after administration of 0.1 mg.kg-1 vecuronium. The Nepalese patients in Nepal had significantly less satisfactory intubating conditions (p = 0.002). Similarly, male patients had significantly less satisfactory conditions than female patients (p = 0.004). Some anthropometric measurements were significantly different between the patients in Nepal and those in Hong Kong. There were also sex-related anthropometric differences. It is suggested that differences in response to vecuronium could be explained by differences in distribution volume and muscle mass.

Adult↗
PubMed1992

Plasma catecholamine levels following topical application versus infiltration of adrenaline for nasal surgery.

Plasma catecholamine concentrations were measured after vasoconstrictor solutions were administered either by instillation (Moffett's method) or by submucosal infiltration in twenty patients undergoing elective nasal surgery. Following infiltration with 4.4 ml of 1:80,000 adrenaline and 2% lignocaine, plasma adrenaline concentrations increased by 44.3 times to a peak of 9.9 nmol.l-1 (1813 pg.ml-1) within one minute. In contrast the peak level of adrenaline in the patients receiving Moffett's solution containing 1 ml of 1:1,000 adrenaline was 1.27 nmol.l-1 (232 pg.ml-1) occurring 10 minutes after instillation of the solution. The difference in the adrenaline concentrations between the groups was statistically significant (P less than 0.01). The lack of sympathoneuronal response was confirmed by simultaneous measurements of plasma noradrenaline concentrations, which did not change significantly. The operative field was subjectively assessed to be better in the infiltrated patients and the mean operating time and measured blood loss were less in this same group of patients.

Administration, Topical↗
PubMed1992

A clinical evaluation of the Hemocue haemoglobinometer using capillary, venous and arterial samples.

The 'Hemocue' device for rapid estimation of haemoglobin concentration was evaluated in a clinical setting. Repeatable accuracy of capillary, venous and arterial samples was examined and then compared with standard laboratory venous haemoglobin estimates using a 'Coulter JT' analyser in 42 patients. The mean values for haemoglobin (g/l) and coefficient of variation were capillary 108.2 (8.0); venous 104.9 (2.2); arterial 105.9 (2.0); and laboratory venous 104.6 (1.3). Although the mean haemoglobin values were similar, capillary samples were significantly less repeatable than venous or arterial samples (Pitman test, P < 0.001). Comparison of variance between the laboratory sample and each sampling technique demonstrated that capillary samples were significantly more variable than venous or arterial samples. Peripheral skin temperature did not influence the accuracy of capillary samples. Hemocue estimations of venous samples were found to be as accurate as laboratory estimations. The lack of repeatable accuracy of capillary estimations was sufficiently large that their use cannot be recommended in clinical practice.

Adolescent↗
PubMed1991

Plasma catecholamines and oxygen consumption during weaning from mechanical ventilation.

Previous studies on oxygen consumption (VO2) during weaning from mechanical ventilation assumed that an increase in VO2 (delta VO2) reflected oxygen consumption by respiratory muscles (VO2RESP), and proposed delta VO2 as a weaning predictor. We measured VO2 CO2 production (VCO2) and plasma catecholamines in 20 short-term ventilated patients during weaning by SIMV and CPAP. delta VO2 as a percentage of VO2 during spontaneous ventilation (delta VO2%) ranged from 4.8% to 41.5%. VCO2 also increased and correlated with VO2. Plasma adrenaline and noradrenaline increased significantly to levels known to produce considerable increases in metabolic rate. Mean arterial pressure and heart rate concomitantly increased, but spontaneous minute ventilation decreased. Thus, since the increased plasma catecholamines are calorigenic, the assumption that delta VO2 represents VO2RESP is incorrect. Although mean delta VO2% of successfully weaned patients was significantly less than that of failure-to-wean patients, the wide scatter of individual values in the latter group excludes delta VO2% as an accurate weaning predictor.

Adult↗
PubMed1991

Disposition of propofol infusions for caesarean section.

The disposition of propofol was studied in women undergoing elective Caesarean section. Indices of maternal recovery and neonatal assessment were correlated with venous concentrations of propofol. After induction of anaesthesia with propofol 2.0 mg.kg-1, ten patients received propofol 6 mg.kg-1.hr-1 with nitrous oxide 50 per cent in oxygen (low group) and nine were given propofol 9 mg.kg-1.hr-1 with oxygen 100 per cent (high group). Pharmacokinetic variables were similar between the groups. The mean +/- SD Vss = 2.38 +/- 1.16 L.kg-1, Cl = 39.2 +/- 9.75 ml.min-1.kg-1 and t1/2 beta = 126 +/- 68.7 min. At the time of delivery (8-16 min), the concentration of propofol ranged from 1.91-3.82 micrograms.ml-1 in the maternal vein (MV), 1.00-2.00 micrograms.ml-1 in the umbilical vein (UV) and 0.53-1.66 micrograms.ml-1 in the umbilical artery (UA). Neonates with high UV concentrations of propofol at delivery had lower neurologic and adaptive capacity scores 15 minutes later. The concentrations of propofol were similar between groups during the infusion but they declined at a faster rate in the low group postoperatively. Maternal recovery times did not depend on the total dose of propofol but the concentration of propofol at the time of eye opening was greater in the high group than the low group (1.74 +/- 0.51 vs 1.24 +/- 0.32 micrograms.ml-1, P less than 0.01). The rapid placental transfer of propofol during Caesarean section requires propofol infusions to be given cautiously, especially when induction to delivery times are long.

Adult↗