Background: Lipophilic opioids and local anesthetics are often given intrathecally in combination... more Background: Lipophilic opioids and local anesthetics are often given intrathecally in combination for labor analgesia. However, the nature of the pharmacologic interaction between these drugs has not been clearly elucidated in humans. Methods: Three hundred nulliparous women randomly received 1 of 30 different combinations of fentanyl and bupivacaine intrathecally using a combined spinal-epidural technique for analgesia in the first stage of labor. Visual analogue scale pain scores were recorded for 30 min. Response was defined by percentage decrease in pain score from baseline at 15 and 30 min. Dose–response curves for individual drugs were fitted to a hyperbolic dose–response model using nonlinear regression. The nature of the drug interaction was determined using dose equivalence methodology to compare observed effects of drug combinations with effects predicted by additivity. Results: The derived dose–response models for individual drugs (doses in micrograms) at 15 min were: Eff...
Vitamin D may have an important role in pain perception. Inadequate vitamin D levels are associat... more Vitamin D may have an important role in pain perception. Inadequate vitamin D levels are associated with suboptimal recovery after surgery. However, the effects of hypovitaminosis D on postoperative pain-related outcomes and its impact on health-related quality of life after surgery are not well understood. The objective of this study was to determine the effects of hypovitaminosis D on postoperative pain-related outcomes and health-related quality of life at 3 months after knee arthroplasty.This was a longitudinal cohort study of 191 consecutive Hong Kong Chinese patients who were given patient-controlled morphine analgesia for up to 72 hours after 214 knee arthroplasties. Serum total 25-hydroxyvitamin D (25-OHD) concentration was assessed by liquid chromatography-tandem mass spectrometry. The primary outcomes were postoperative pain intensity at rest scores (0-72 h), Western Ontario and McMaster Universities (WOMAC) osteoarthritis index (pain, stiffness and function), and moderate...
Due to the neurotoxicity effects of general anesthesia (GA) and sedatives found in animal studies... more Due to the neurotoxicity effects of general anesthesia (GA) and sedatives found in animal studies, there is a general recommendation to avoid nonurgent surgical procedures requiring anesthesia in children younger than 3 years of age. The aim of this study was to determine the incidence of anesthesia-related postoperative cognitive dysfunction (POCD) on the first day (Day 1) and at 6 weeks after elective noncardiac surgery in school-age children.This was a prospective cohort study of 118 children undergoing GA and 126 age-matched controls of school children aged 5 to 12 years. All children were given a panel of 4 neuropsychological assessments (Hong Kong List Learning for verbal memory, Visual Matching for processing speed, Visual Memory, and General Comprehension Skill from the Hong Kong Wechsler Intelligence Scale for Children). The primary outcome was the incidence of POCD on Day 1 and at 6 weeks after surgery. POCD was defined as when at least 2 of the 4 cognitive function tests ...
Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine, 2012
To determine the point prevalence of elective surgical case cancellations and the reasons. Cross-... more To determine the point prevalence of elective surgical case cancellations and the reasons. Cross-sectional study. Teaching hospital, Hong Kong. PATIENTS; Operating theatre records of elective surgery cancellations from 1 January 2009 to 31 December 2009 were retrospectively reviewed. MAIN OUTCOME MEASURES. Cancellation of scheduled elective surgery on the day of surgery and the corresponding reasons. Of 6234 cases scheduled, 476 were cancelled, which yielded a point prevalence of 7.6%, with a 95% confidence interval of 7.0-8.3%. The highest number of cancellations occurred in patients scheduled for major general surgical procedures (n=94, 20%), major urological procedures (n=64, 13%), major orthopaedic surgery (n=38, 8%), and ultra-major cardiothoracic surgery (n=29, 6%). The most common category for cancellation was facility (73%), followed by work-up (17%), patient (10%), and surgeon (1%). No available operating room time due to overrun of the previous surgery was the most common ...
Background The potencies of bupivacaine and ropivacaine have been compared using up-and-down meth... more Background The potencies of bupivacaine and ropivacaine have been compared using up-and-down methodology, but their complete dose-response curves have not been compared. The authors performed a random allocation-graded dose-response study of epidural bupivacaine and ropivacaine given epidurally for labor analgesia. Methods Three hundred laboring nulliparous patients were randomly given epidural bupivacaine (5, 10, 15, 20, 30, or 40 mg) or ropivacaine (7, 15, 20, 30, 45, or 60 mg) in 20 ml of saline. Visual Analog Scale pain scores were recorded for 30 min. Response was defined by the percentage decrease in pain score from baseline at 30 min, and dose-response data were analyzed by using nonlinear regression. Results Sigmoidal Emax model dose-response curves were fitted to the datasets for bupivacaine (R = 0.53) and ropivacaine (R = 0.59). The curves had similar steepness (Hill coefficient 2.02 [95% CI, 1.55-2.50] vs. 2.25 [1.70-2.79], P = 0.55). The ED50 (dose of the drug that reduc...
Background The use of traditional Chinese herbal medicines (TCHMs) among the presurgical populati... more Background The use of traditional Chinese herbal medicines (TCHMs) among the presurgical population is widespread, but their impact on perioperative patient care is unclear. The authors estimated the incidence and risk of TCHM-related perioperative events. Methods In a Hong Kong cohort study, 601 patients undergoing major elective surgery were asked about their Western medicine and TCHM use in the 2 weeks before surgery. Unanticipated perioperative events were noted by attending anesthesiologists, blinded to patients' use of specific TCHMs. Modified Poisson regression models were used to obtain the relative risk of combined endpoints of perioperative events associated with TCHM use. Results Of the 601 patients, 483 patients (80%) took self-prescribed TCHM, and 47 (8%) took TCHM by prescription (with or without self-prescribed TCHM) in the 2 weeks before surgery. The crude incidences of any combined endpoints of preoperative, intraoperative, and postoperative events were 23% (95%...
Most medical students learn clinical reasoning skills informally during clinical rotations that h... more Most medical students learn clinical reasoning skills informally during clinical rotations that have varying quality of supervision. We conducted a randomized controlled trial to determine if a workshop that uses "illness scripts" could improve students' clinical reasoning skills when making diagnoses of patients portrayed in written scenarios. In 2007--2008, 53 fourth-year medical students were randomly assigned to either a family medicine (intervention) or psychiatry (control) clerkship at The Chinese University of Hong Kong. Students in the intervention group participated in a 3-hour workshop on clinical reasoning that used illness scripts. The workshop was conducted with small-group teaching using a Web-based set of clinical reasoning problems, individualized feedback, and demonstration of tutors' reasoning aloud. The effectiveness of the intervention was assessed…
Background The purpose of this study was to determine an optimum dose of alfentanil, coadminister... more Background The purpose of this study was to determine an optimum dose of alfentanil, coadministered with 2.5 mg/kg propofol, when inserting a classic laryngeal mask airway. Methods Seventy-five adult ethnic Chinese patients with an American Society of Anesthesiologists physiologic status classification I or II and requiring anesthesia for minor surgery with a laryngeal mask were recruited. They were randomly assigned to five dosage groups: placebo or 5, 10, 15, or 20 microg/kg. The study drug plus propofol were administered, and 90 s later, insertion conditions were assessed using a six-category score. The duration of apnea was recorded. A probit analysis was performed and used to estimate the ED50 and ED95 with 95% confidence intervals for each assessment. Results Twenty-five male and 50 female patients, aged 18-59 yr, were studied. The five groups were similar. Laryngeal mask insertion was successful in all but one alfentanil patient. Duration of apnea increased with increasing do...
Background: Lipophilic opioids and local anesthetics are often given intrathecally in combination... more Background: Lipophilic opioids and local anesthetics are often given intrathecally in combination for labor analgesia. However, the nature of the pharmacologic interaction between these drugs has not been clearly elucidated in humans. Methods: Three hundred nulliparous women randomly received 1 of 30 different combinations of fentanyl and bupivacaine intrathecally using a combined spinal-epidural technique for analgesia in the first stage of labor. Visual analogue scale pain scores were recorded for 30 min. Response was defined by percentage decrease in pain score from baseline at 15 and 30 min. Dose–response curves for individual drugs were fitted to a hyperbolic dose–response model using nonlinear regression. The nature of the drug interaction was determined using dose equivalence methodology to compare observed effects of drug combinations with effects predicted by additivity. Results: The derived dose–response models for individual drugs (doses in micrograms) at 15 min were: Eff...
Vitamin D may have an important role in pain perception. Inadequate vitamin D levels are associat... more Vitamin D may have an important role in pain perception. Inadequate vitamin D levels are associated with suboptimal recovery after surgery. However, the effects of hypovitaminosis D on postoperative pain-related outcomes and its impact on health-related quality of life after surgery are not well understood. The objective of this study was to determine the effects of hypovitaminosis D on postoperative pain-related outcomes and health-related quality of life at 3 months after knee arthroplasty.This was a longitudinal cohort study of 191 consecutive Hong Kong Chinese patients who were given patient-controlled morphine analgesia for up to 72 hours after 214 knee arthroplasties. Serum total 25-hydroxyvitamin D (25-OHD) concentration was assessed by liquid chromatography-tandem mass spectrometry. The primary outcomes were postoperative pain intensity at rest scores (0-72 h), Western Ontario and McMaster Universities (WOMAC) osteoarthritis index (pain, stiffness and function), and moderate...
Due to the neurotoxicity effects of general anesthesia (GA) and sedatives found in animal studies... more Due to the neurotoxicity effects of general anesthesia (GA) and sedatives found in animal studies, there is a general recommendation to avoid nonurgent surgical procedures requiring anesthesia in children younger than 3 years of age. The aim of this study was to determine the incidence of anesthesia-related postoperative cognitive dysfunction (POCD) on the first day (Day 1) and at 6 weeks after elective noncardiac surgery in school-age children.This was a prospective cohort study of 118 children undergoing GA and 126 age-matched controls of school children aged 5 to 12 years. All children were given a panel of 4 neuropsychological assessments (Hong Kong List Learning for verbal memory, Visual Matching for processing speed, Visual Memory, and General Comprehension Skill from the Hong Kong Wechsler Intelligence Scale for Children). The primary outcome was the incidence of POCD on Day 1 and at 6 weeks after surgery. POCD was defined as when at least 2 of the 4 cognitive function tests ...
Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine, 2012
To determine the point prevalence of elective surgical case cancellations and the reasons. Cross-... more To determine the point prevalence of elective surgical case cancellations and the reasons. Cross-sectional study. Teaching hospital, Hong Kong. PATIENTS; Operating theatre records of elective surgery cancellations from 1 January 2009 to 31 December 2009 were retrospectively reviewed. MAIN OUTCOME MEASURES. Cancellation of scheduled elective surgery on the day of surgery and the corresponding reasons. Of 6234 cases scheduled, 476 were cancelled, which yielded a point prevalence of 7.6%, with a 95% confidence interval of 7.0-8.3%. The highest number of cancellations occurred in patients scheduled for major general surgical procedures (n=94, 20%), major urological procedures (n=64, 13%), major orthopaedic surgery (n=38, 8%), and ultra-major cardiothoracic surgery (n=29, 6%). The most common category for cancellation was facility (73%), followed by work-up (17%), patient (10%), and surgeon (1%). No available operating room time due to overrun of the previous surgery was the most common ...
Background The potencies of bupivacaine and ropivacaine have been compared using up-and-down meth... more Background The potencies of bupivacaine and ropivacaine have been compared using up-and-down methodology, but their complete dose-response curves have not been compared. The authors performed a random allocation-graded dose-response study of epidural bupivacaine and ropivacaine given epidurally for labor analgesia. Methods Three hundred laboring nulliparous patients were randomly given epidural bupivacaine (5, 10, 15, 20, 30, or 40 mg) or ropivacaine (7, 15, 20, 30, 45, or 60 mg) in 20 ml of saline. Visual Analog Scale pain scores were recorded for 30 min. Response was defined by the percentage decrease in pain score from baseline at 30 min, and dose-response data were analyzed by using nonlinear regression. Results Sigmoidal Emax model dose-response curves were fitted to the datasets for bupivacaine (R = 0.53) and ropivacaine (R = 0.59). The curves had similar steepness (Hill coefficient 2.02 [95% CI, 1.55-2.50] vs. 2.25 [1.70-2.79], P = 0.55). The ED50 (dose of the drug that reduc...
Background The use of traditional Chinese herbal medicines (TCHMs) among the presurgical populati... more Background The use of traditional Chinese herbal medicines (TCHMs) among the presurgical population is widespread, but their impact on perioperative patient care is unclear. The authors estimated the incidence and risk of TCHM-related perioperative events. Methods In a Hong Kong cohort study, 601 patients undergoing major elective surgery were asked about their Western medicine and TCHM use in the 2 weeks before surgery. Unanticipated perioperative events were noted by attending anesthesiologists, blinded to patients' use of specific TCHMs. Modified Poisson regression models were used to obtain the relative risk of combined endpoints of perioperative events associated with TCHM use. Results Of the 601 patients, 483 patients (80%) took self-prescribed TCHM, and 47 (8%) took TCHM by prescription (with or without self-prescribed TCHM) in the 2 weeks before surgery. The crude incidences of any combined endpoints of preoperative, intraoperative, and postoperative events were 23% (95%...
Most medical students learn clinical reasoning skills informally during clinical rotations that h... more Most medical students learn clinical reasoning skills informally during clinical rotations that have varying quality of supervision. We conducted a randomized controlled trial to determine if a workshop that uses "illness scripts" could improve students' clinical reasoning skills when making diagnoses of patients portrayed in written scenarios. In 2007--2008, 53 fourth-year medical students were randomly assigned to either a family medicine (intervention) or psychiatry (control) clerkship at The Chinese University of Hong Kong. Students in the intervention group participated in a 3-hour workshop on clinical reasoning that used illness scripts. The workshop was conducted with small-group teaching using a Web-based set of clinical reasoning problems, individualized feedback, and demonstration of tutors' reasoning aloud. The effectiveness of the intervention was assessed…
Background The purpose of this study was to determine an optimum dose of alfentanil, coadminister... more Background The purpose of this study was to determine an optimum dose of alfentanil, coadministered with 2.5 mg/kg propofol, when inserting a classic laryngeal mask airway. Methods Seventy-five adult ethnic Chinese patients with an American Society of Anesthesiologists physiologic status classification I or II and requiring anesthesia for minor surgery with a laryngeal mask were recruited. They were randomly assigned to five dosage groups: placebo or 5, 10, 15, or 20 microg/kg. The study drug plus propofol were administered, and 90 s later, insertion conditions were assessed using a six-category score. The duration of apnea was recorded. A probit analysis was performed and used to estimate the ED50 and ED95 with 95% confidence intervals for each assessment. Results Twenty-five male and 50 female patients, aged 18-59 yr, were studied. The five groups were similar. Laryngeal mask insertion was successful in all but one alfentanil patient. Duration of apnea increased with increasing do...
Uploads
Papers by Anna Lee