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Biomedical subjects

F Chung

Publications and source records attributed to F Chung.

At least 37 records · Page 2Linked to original sources
PubMed2000

A comparison of anaesthesia using remifentanil combined with either isoflurane, enflurane or propofol in patients undergoing gynaecological laparoscopy, varicose vein or arthroscopic surgery.

BACKGROUND: Anaesthesia comprising remifentanil plus isoflurane, enflurane or propofol was randomly evaluated in 285, 285 and 284 patients, respectively, undergoing short-procedure surgery. METHODS: Anaesthesia was induced with propofol (0.5 mg x kg(-1) and 10 mg x 10 s(-1)), and a remifentanil bolus (1 microg x kg(-1)) and infusion at 0.5 microg x g(-1) x min(-1). Five minutes after intubation, remifentanil infusion was halved and 0.5 MAC of isoflurane or enflurane, or propofol at 100 microg x kg(-1) x min(-1) were started and titrated for maintenance. RESULTS: Patient demography and anaesthesia duration were similar between the groups. Surgery was performed as daycases (52%) or inpatients (48%). The median times (5-7 min) to extubation and postoperative recovery were similar between the groups. Responses to tracheal intubation (15% vs 8%) and skin incision (13% vs 7%) were significantly greater in the total intravenous anaesthesia (TIVA) group (P<0.05). Fewer patients given remifentanil and isoflurane (21%) or enflurane (19%) experienced > or =1 intraoperative stress response compared to the TIVA group (28%) (P<0.05). Median times to qualification for and actual recovery room discharge were 0.5-0.6 h and 1.1-1.2 h, respectively. The most common remifentanil-related symptoms were muscle rigidity (6-7%) at induction, hypotension (3-5%) and bradycardia (1-4%) intraoperatively and, shivering (6-7%), nausea and vomiting postoperatively. Nausea (7%) and vomiting (3%) were significantly lower with TIVA compared with inhaled anaesthetic groups (14-15% and 6-8%, respectively; P<0.05). CONCLUSION: Anaesthesia combining remifentanil with volatile hypnotics or TIVA with propofol was effective and well tolerated. Times of extubation, postanaesthesia recovery and recovery room discharge were rapid, consistent and similar for all three regimens.

Adolescent↗
PubMed2000

Succinylcholine-associated postoperative myalgia.

The subject of postoperative myalgia associated with the use of succinylcholine is reviewed. We discuss the mechanisms of succinylcholine-induced myalgia and the techniques available to prevent and treat the myalgia. In situations where patients are at risk of developing myalgia and succinylcholine is the neuromuscular blocker of choice, the use of a combination of techniques may prove to be a useful strategy.

Fasciculation↗
PubMed2000

A comparative study on the behavior of three different automatic mode switching dual chamber pacemakers to intracardiac recordings of clinical atrial fibrillation.

Automatic mode switching (AMS) allows patients with dual chamber pacemakers who develop paroxysmal AF to have a controlled ventricular rate. The aim of this study was to (1) compare the rate-controlled behavior of three AMS algorithms in response to AF, in terms of speed and stability of response and resynchronization to sinus rhythm, and (2) compare the influence of pacemaker programming on optimal mode switching. We studied 17 patients (12 men, 5 women; mean age 59 +/- 15 years) who developed AF during electrophysiological study. Unfiltered bipolar atrial electrograms during sinus rhythm and AF were recorded onto high fidelity tapes and replayed into the atrial port of three dual chamber pacemakers with different mode switching algorithms (Thera, Marathon, Meta). The Thera pacemaker uses rate smoothing, and mode switches occur when mean sensed atrial rate exceeds the predefined AMS rate (MR). Marathon mode switches after a programmable number of consecutive rapid atrial events (NR). Meta DDDR monitors the atrial rate by a counter for atrial cycles faster than the programmed AMS rate. It increases or decreases the counter if the atrial cycle length is shorter or longer than the programmed AMS interval, respectively. Mode switch occurs when the AF detection criteria are met (CR). A total of 260 rhythms were studied. NR was significantly faster than MR and CR (latency 2.5 +/- 3 s vs 26 +/- 7 s vs 15 +/- 22 s, respectively, P < 0.0001). During sustained AF, MR resulted in the most stable and regular ventricular rhythm compared to NR or CR. In CR, ventricular rate oscillated between AMS and atrial tracking (cycle length variations: 44 +/- 2 s vs 346 +/- 109 s vs 672 +/- 84 s, P < 0.05). At resumption of sinus rhythm, MR resynchronized after 143 +/- 22 s versus 3.4 +/- 0.7 s for NR and 5.9 +/- 1.1 s for CR, resulting in long periods of AV dissociation when a VVI/VVIR mode is used after AMS. Programming of atrial refractory periods did not affect AMS response, although the speed of AMS onset can be adjusted by programming of onset criteria in the Meta DDDR. AMS algorithms differ in their ability to handle recorded clinical atrial arrhythmias. The rapid-responding algorithm exhibits rate instability, whereas slow responding algorithm shows a long delay in response and risk of AV dissociation. Thus different instrumentation of AMS may have clinical implications in patients with dual chamber pacemakers who develop AF.

Adult↗
PubMed2000

Modulation of growth of human prostate cancer cells by the N-acetylcysteine conjugate of phenethyl isothiocyanate.

There is growing evidence that thiol conjugates of isothiocyanates present in cruciferous vegetables are effective cancer chemopreventive and potentially active therapeutic agents. The effects of the N-acetylcysteine conjugate of phenethyl isothiocyanate (PEITC-NAC) on tumor cell growth were analyzed in human prostate cancer cell lines LNCaP, androgen-dependent, and DU-145, androgen-independent. Exposure of the cells to PEITC-NAC at high concentrations caused cytolysis, while at lower concentrations PEITC-NAC mediated a dose-dependent growth modulation, with reduction of DNA synthesis and growth rate, inhibition of clonogenicity and induction of apoptosis in both types of prostate cancer cells. PEITC-NAC decreased cells in S and G2M phases of cell cycle, blocking cells entering replicating phases. In parallel, a significant enhancement of cells expressing the cell cycle regulator p21 as well as its intensity was determined using a fluorescent antibody technique. The action of PEITC-NAC was time-dependent, with the magnitude of inhibition increasing to 50-65% after PEITC-NAC exposure for several days. Interaction of tumor cells with dissociation products of PEITC-NAC, PEITC and NAC, are proposed as the mechanism of growth regulation.

Anticarcinogenic Agents↗
PubMed1999

Femoral nerve block and ketorolac in patients undergoing anterior cruciate ligament reconstruction.

PURPOSE: The primary objective was to evaluate the analgesic effectiveness of femoral nerve block and ketorolac following ACL reconstruction. The secondary objective was to examine their effects on recovery milestones. METHODS: Prior to standard general anesthesia, 90 patients were randomized into three groups of preoperative treatment: 1) femoral nerve block (15 mL bupivacaine 0.5%) and 1 mL normal saline i.v. (FNB group); 2) placebo femoral nerve block (15 mL normal saline) and 30 mg (1 mL) ketorolac i.v. (KT group); 3) placebo femoral nerve block (15 mL normal saline) and 1 mL normal saline i.v. (PL group). Postoperatively, pain was assessed by visual analogue score, demand and consumption of morphine via patient-controlled analgesia pump. The times for patients to tolerate oral fluid, food, sit up, ambulate and void were also noted. RESULTS: Morphine consumption within one hour, three hours and until POD 1 in the FNB group was lower than the PL group (7 +/- 6, 11 +/- 9, 27 +/- 23 mg vs 13 +/- 5, 20 +/- 9, 49 +/- 28 mg respectively), whereas only that within one hour in the KT group was lower than the PL group. Pain score was lower in FNB and KT groups in the first postoperative hour than in the PL group (P < 0.05). There were no differences among the three groups in the times to meet recovery milestone and discharge criteria. CONCLUSION: Femoral nerve block provides superior analgesia than placebo for ACL reconstruction but was insufficient to facilitate early recovery.

Adolescent↗
PubMed1999

Adverse events in ambulatory surgery. A comparison between elderly and younger patients.

PURPOSE: An increasing number of elderly patients are undergoing ambulatory surgery. We examined whether ambulatory surgery carries a higher risk for the elderly than for younger patients. METHODS: A total of 17,638 consecutive ambulatory surgical patients were enrolled in a prospective cohort study during a three-year period. Preoperative, intraoperative, and postoperative information was collected. Twenty-seven percent of the enrolled patients were 65 yr or older. Incidence rates of intraoperative and postoperative adverse events among the elderly were compared with those among younger patients; we controlled for sex, ASA physical status, body mass index, type of surgery, and duration of procedure, using multiple logistic regression models. RESULTS: Elderly patients had a higher incidence of any intraoperative event (adjusted odds ratio, 1.4; 99.7% confidence interval [CI], 1.0-2.0) and of intraoperative cardiovascular events (adjusted odds ratio, 2.0; 99.7% CI, 1.3-3.0). They also had a lower incidence of any postoperative event (adjusted odds ratio, 0.4; 99.7% CI, 0.3-0.6) and of postoperative pain (adjusted odds ratio, 0.2; 99.7% CI, 0.1-0.4), nausea and vomiting (adjusted odds ratio, 0.3; 99.7% CI, 0.1-0.6), and dizziness (adjusted odds ratio, 0.4; 99.7% CI, 0.2-1.0). CONCLUSION: The risks reported do not constitute a contraindication for elderly patients to undergo ambulatory surgery but this population may require more careful intraoperative cardiovascular management.

Adult↗
PubMed1999

Postoperative pain control in ambulatory surgery.

Optimizing postoperative pain control is the key to further advancement in the field of ambulatory anesthesia. The current situation in postoperative pain management indicates room for improvement, especially in the area of patient education and the development of individualized discharge analgesic packages. Multimodal analgesia provides superior analgesia with a lower side-effect profile. Preoperative administration of analgesia would decrease the intraoperative analgesic requirement, which may lead to a smooth and rapid recovery. Finally, new, portable analgesic delivery systems are under investigation and may prove to be the method of choice for future postoperative pain, management in ambulatory anesthesia.

Ambulatory Surgical Procedures↗
PubMed1999

Postoperative sore throat: cause, prevention and treatment.

Sore throat is a common postoperative complaint, occurring most often following tracheal intubation. Factors such as tracheal-tube size and cuff design have been shown to be important causative factors. Routine tracheal intubation for elective surgical procedures can result in pathological changes, trauma and nerve damage which may also account for postoperative throat symptoms. Sore throat following the use of a laryngeal mask appears to be related to the technique of insertion but the contribution of intracuff pressure remains to be clarified. It would appear, however, that high intracuff pressure is associated with nerve palsies due to neuropraxia and nerve compression. Careful insertion techniques for both the tracheal tube and laryngeal mask are of paramount importance in the prevention of airway trauma and postoperative sore throat.

Humans↗
PubMed1999

Ondansetron is more effective than metoclopramide for the treatment of opioid-induced emesis in post-surgical adult patients. Ondansetron OIE Post-Surgical Study Group.

Nausea and vomiting are common side effects of opioids administered for pain control. This double-blind, randomized, parallel-group study evaluated the anti-emetic efficacy and tolerability of single intravenous (i.v.) doses of ondansetron 8 mg, ondansetron 16 mg and metoclopramide 10 mg in the treatment of opioid-induced emesis. Adult patients undergoing low emetogenic surgical procedures, using a standardized anaesthesia regimen were assessed for 24 h following administration of study anti-emetic to treat established post-surgical opioid-induced emesis. A total of 4511 patients were enrolled of whom 1366 experienced opioid-induced emesis and received randomized study medication. Ondansetron 8 mg and 16 mg were significantly better than metoclopramide 10 mg (P < 0.05) for both complete control of emesis, complete control of nausea and other efficacy measures. There were no significant differences between the two ondansetron groups. All three treatments were well tolerated. In conclusion, this large, multicentre study demonstrates that ondansetron is more effective than metoclopramide in the treatment of opioid-induced emesis following administration of post-surgical opioids to control pain.

Adolescent↗
PubMed1999

Pre-existing medical conditions as predictors of adverse events in day-case surgery.

We have developed mathematical models to estimate the risk of perioperative adverse events in patients with pre-existing conditions undergoing day-case surgery. We studied 17,638 consecutive day-case surgical patients in a prospective study. Preoperative, intraoperative and postoperative data were collected. Risk modelling was performed with backward stepwise multiple logistic regression and validated on a separate subset of our patients. Eighteen pre-existing conditions were entered into the model. We adjusted for age, sex, and duration and type of surgery. Seven associations between pre-existing medical conditions and perioperative adverse events were statistically significant. Hypertension predicted the occurrence of any intraoperative event and intraoperative cardiovascular events. Obesity predicted intraoperative and postoperative respiratory events, and smoking and asthma predicted postoperative respiratory events. Gastro-oesophageal reflux predicted intubation-related events. The presented models of risk estimation were validated internally and provided a useful tool for accurate risk estimation.

Adolescent↗
PubMed1999

Factors contributing to a prolonged stay after ambulatory surgery.

UNLABELLED: We identified predictors for prolonged postoperative stay after ambulatory surgery using multiple logistic regression models. We collected perioperative data for 16,411 ambulatory surgical patients. A log-transformed time to discharge variable was modeled by multiple linear regression, including patient-, anesthesia-, and surgery-specific variables. The impact of hypothetical elimination of perioperative adverse events on mean length of stay was also estimated. Separate analyses were performed among patients who received general anesthesia (GA) and monitored anesthesia care (MAC). Patients receiving GA stayed 50 min longer than patients receiving MAC. Patients receiving GA and undergoing strabismus, transurethral, or otorhinolaryngological/dental procedures had the longest postoperative stay. Among patients receiving GA, smokers had a 4% shorter stay compared with nonsmokers; among patients receiving MAC, those with congestive heart failure (CHF) had a 11% longer stay compared with patients without CHF. Postoperative nausea and vomiting, dizziness, excessive pain, and cardiovascular events predicted 22%-79% increases in postoperative stay. The hypothetical elimination of all adverse events resulted in a 9.6% decrease in mean length of stay among patients receiving GA, but in only a 3.8% decrease among patients receiving MAC. The length of postoperative stay among ambulatory surgical patients is mainly determined by the type of surgery and by adverse events, such as excessive pain, postoperative nausea and vomiting, dizziness, drowsiness, and cardiovascular events. Patients with CHF and those who underwent long procedures had a higher risk of a prolonged stay. Appropriate prevention and management of postoperative symptoms could significantly decrease the length of stay among patients receiving GA. IMPLICATIONS: The length of postoperative stay among ambulatory surgical patients is mainly determined by the type of surgery and by adverse events, such as excessive pain, postoperative nausea and vomiting, dizziness, drowsiness, and untoward cardiovascular events. Patients with congestive heart failure and those who underwent long procedures had a higher risk of a prolonged stay. Appropriate prevention and management of postoperative symptoms could significantly decrease the length of stay among patients receiving general anesthesia.

Adult↗
PubMed1999

Can postoperative nausea and vomiting be predicted?

BACKGROUND: Iletrospective studies fail to identify predictors of postoperative nausea and vomiting (PONV). The authors prospectively studied 17,638 consecutive outpatients who had surgery to identify predictors. METHODS: Data on medical conditions, anesthesia, surgery, and PONV were collected in the post-anesthesia care unit, in the ambulatory surgical unit, and in telephone interviews conducted 24 h after surgery. Multiple logistic regression with backward stepwise elimination was used to develop a predictive model An independent set of patients was used to validate the model RESULTS: Age (younger or older), sex (female or male), smoking status (nonsmokers or smokers), previous PONV, type of anesthesia (general or other), duration of anesthesia (longer or shorter), and type of surgery (plastic, orthopedic shoulder, or other) were independent predictors of PONV. A 10-yr increase in age decreased the likelihood of PONV by 13%. The risk for men was one third that for women. A 30-min increase in the duration of anesthesia increased the likelihood of PONV by 59%. General anesthesia increased the likelihood of PONV 11 times compared with other types of anesthesia. Patients with plastic and orthopedic shoulder surgery had a sixfold increase in the risk for PONV. The model predicted PONV accurately and yielded an area under the receiver operating characteristic curve of 0.785+/-0.011 using an independent validation set. CONCLUSIONS: A validated mathematical model is provided to calculate the risk of PONV in outpatients having surgery. Knowing the factors that predict PONV will help anesthesiologists determine which patients will need antiemetic therapy.

Adult↗
PubMed1999

Comparison of the intubation conditions provided by rapacuronium (ORG 9487) or succinylcholine in humans during anesthesia with fentanyl and propofol.

BACKGROUND: Currently, the only approved muscle relaxant with a rapid onset and short duration of action is succinylcholine, a drug with some undesirable effects. Rapacuronium is an investigational nondepolarizing relaxant that also has a rapid onset and short duration and consequently should be compared with succinylcholine in its ability to facilitate rapid tracheal intubation. METHODS: This prospective, randomized clinical trial involved 336 patients. Anesthesia was induced with fentanyl and propofol and either 1.5 mg/kg rapacuronium or 1.0 mg/kg succinylcholine. The goal was to accomplish tracheal intubation by 60 s after administration of the neuromuscular blocking drug. Endotracheal intubation was performed, and conditions were graded by a blinded investigator. Recovery of neuromuscular function was assessed by electromyography. RESULTS: Intubation conditions were evaluated in 236 patients. Intubation by 60 s after drug administration occurred in 100% of patients with rapacuronium and in 98% with succinylcholine. Intubation conditions were excellent or good in 87% of patients with rapacuronium and in 95% with succinylcholine (P < 0.05). The time (median and range) to the first recovery of the train-of-four response was 8.0 (2.8-20.0) min with rapacuronium and 5.7 (1.8-17.7) min with succinylcholine (P < 0.05). The overall incidence of adverse effects was similar with both drugs. CONCLUSIONS: A 1.5-mg/kg dose of rapacuronium effectively facilitates rapid tracheal intubation. It can be considered a valid alternative to 1.0 mg/kg succinylcholine for this purpose.

Adolescent↗
PubMed1999

Return hospital visits and hospital readmissions after ambulatory surgery.

OBJECTIVE: To determine the overall and complication-related readmission rates within 30 days after ambulatory surgery at a major ambulatory surgical center. SUMMARY BACKGROUND DATA: Currently in North America, 65% of the surgical procedures are carried out in ambulatory settings. The safety of ambulatory surgery is well documented, with low rates of adverse events during or immediately after surgery. The consequences of ambulatory surgery during an extended period, however, have not been studied extensively. METHODS: Preoperative, intraoperative, and postoperative data were collected on 17,638 consecutive patients undergoing ambulatory surgery at a major ambulatory surgical center in Toronto, Ontario. With the use of the database of the Ontario Ministry of Health, the authors identified all return hospital visits and hospital readmissions occurring in Ontario within 30 days after the ambulatory surgery. Return visits were categorized as emergency room visits, ambulatory surgical unit admissions, or inpatient admissions. The readmissions were categorized as those resulting from surgical, medical, or anesthesia-related complications or those not related to the ambulatory surgery. RESULTS: One hundred ninety-three readmissions occurred within 30 days after ambulatory surgery (readmission rate 1.1%). Six patients returned to the emergency room, 178 patients were readmitted to the ambulatory surgical unit, and 9 patients were readmitted as inpatients. Twenty-five readmissions were the result of surgical complications, and one resulted from a medical complication (pulmonary embolism). The complication-related readmission rate was 0.15% (1 in 678 procedures). The complication rate was significantly higher among patients undergoing transurethral resection of bladder tumor (5.7%). No anesthesia-related readmissions or deaths were identified. CONCLUSIONS: The rate of complication-related readmissions was extremely low (0.15%). This result further supports the view that ambulatory surgery is a safe practice.

Adolescent↗
PubMed1999

Cardiopulmonary responses of middle-aged men without cardiopulmonary disease to steady-rate positive and negative work performed on a cycle ergometer.

BACKGROUND AND PURPOSE: Understanding physiological responses to negative work allows therapists to be more knowledgeable when they prescribe this form of exercise. The physiological responses of 12 men without cardiopulmonary disease, aged 39 to 65 years (X=49.7, SD=9.3), to negative work (eccentric muscle contractions) and to positive work (concentric muscle contractions) were compared. SUBJECTS AND METHODS: Subjects performed the 2 types of work on a motorized cycle ergometer at pedaling frequencies of 35, 55, and 75 rpm with a constant power output of 60 W. Steady-rate values of oxygen consumption (VO2), heart rate (HR), minute ventilation (VE), tidal volume (VT), and breathing frequency (fb) were obtained during 6 test conditions (positive and negative work at each of the 3 pedaling frequencies). RESULTS: Values for all measures were greater during positive work than during negative work, except for fb. During positive work, values for all variables were greatest at 75 rpm, except for fb. During negative work, VO2 and HR were greater at 75 and 35 rpm than at 55 rpm, and VE and VT were greater at 75 rpm than at 55 rpm. Breathing frequency was not different among pedaling frequencies. CONCLUSION AND DISCUSSION: The results confirmed that negative work performed on a cycle ergometer is associated with low metabolic cost in older men without cardiopulmonary disease. Although VE was determined primarily by changes in VT during negative work, a comparable disproportionate increase in fb was observed at the start of negative work. Such changes in breathing patterns have implications for the prescription of negative work for patients with lung disease.

Adult↗