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L C Tsen

Publications and source records attributed to L C Tsen.

At least 19 recordsLinked to original sources
PubMed2006

Resident training in obstetric anesthesia in the United States.

BACKGROUND: Limited information exists on obstetric anesthesia experience and training within residency training programs in the United States. METHODS: A survey was sent to every academic anesthesiology training program in the United States (n=120), with follow-up reminders to non-responders. The survey included 14 questions divided into staffing, didactic teaching and epidemiology regarding the practice of obstetric anesthesia at each academic institution. RESULTS: A response rate of 78% (93/120) was achieved. The returned surveys were grouped into three tiers by the number of deliveries/year from the lowest (Group 1) to the highest (Group 3). The total number of obstetric deliveries at each institution ranged from 340 to 15 800. The average number of residents/month rotating on obstetric anesthesia was 2.6 and the number of months spent on the obstetric anesthesia service was 2.7. The average number of obstetric anesthesia lectures given was 12 per month. A total of 21.5 obstetric anesthesia fellows were reported to train at these institutions, with fellows being more common in larger institutions. Group 1 institutions were more likely to have anesthesiologists covering the main operating room and obstetric suite simultaneously. The average number of obstetric anesthesia staff members/institution was 4.3. The average cesarean section rate was 27.8%, with 5.8% being performed under general anesthesia. Neuraxial techniques were used in an average of 70.3% of laboring parturients, with combined spinal epidurals accounting for 24.6% of the techniques. CONCLUSION: The average number of obstetric deliveries per year for institutions with a resident training program was 3498+/-2383. Dedicated obstetric anesthesia staffing was more common when >3700 deliveries/year were performed; the presence of this staffing corresponded with a reduction in the use of general anesthesia for cesarean deliveries. Few differences in the resident lecture didactic exposure were observed in terms of numbers of lectures and months on the obstetric anesthesia service, although a significantly greater number of clinical cases was available to each resident in those institutions with greater overall numbers of obstetric cases.

Anesthesia, Conduction↗
PubMed2005

Placental growth factor in the cerebrospinal fluid of women with preeclampsia.

OBJECTIVE: Recent data suggest that excess circulating soluble fms-like tyrosine kinase-1 (sFlt-1) may causally relate to preeclampsia. This study investigates the levels of sFlt-1, VEGF, and PlGF in cerebrospinal fluid (CSF) of patients with preeclampsia and normotensive controls. METHODS: CSF was collected from preeclamptic patients (n=15) and controls (n=7) at the time of spinal anesthesia and assayed for PlGF, sFlt-1, and VEGF (total and free) by specific immunoassays. RESULTS: All sought angiogenic factors were measurable. Levels of free PlGF but not sFlt-1 or VEGF (total or free) were increased in CSF of preeclamptic women. There was no significant difference in the ratios of angiogenic factors in the CSF of women with preeclampsia. There was no correlation between levels of angiogenic factors and CSF cell counts or severity of symptoms. CONCLUSION: Elevated levels of PlGF in CSF preeclamptic women may promote vascular permeability and contribute to the hypertensive encephalopathy seen in such patients.

Adult↗
PubMed2005

Hemodynamic effects of spinal anesthesia and simultaneous intravenous bolus of combined phenylephrine and ephedrine versus ephedrine for cesarean delivery.

BACKGROUND: Hypotension following spinal anesthesia for cesarean delivery can produce adverse maternal symptoms and neonatal acid-base effects. Single-agent prophylaxis, most notably with ephedrine, does not reliably prevent spinal anesthesia-induced hypotension; recently, however, the prophylactic use of phenylephrine with ephedrine as an infusion was observed to be effective. We postulated that this combination, when given as an intravenous bolus for prophylaxis and rescue treatment, could be similarly effective. METHOD: Forty-three term parturients were randomized to receive a bolus of ephedrine 10 mg +/- phenylephrine 40 microg (groups E and EP, respectively) simultaneously with spinal anesthesia. Hypotension was defined as a systolic blood pressure below 100 mmHg or a decrease of 20% from a baseline value. Rescue boluses comprised of ephedrine 5 mg +/- phenylephrine 20 microg. RESULTS: For groups E and EP, respectively, the incidence of hypotension was 80% vs. 95% (P=0.339), with the mean number of rescue boluses being 3.85+/-3.7 and 3.05+/-1.7 and the mean umbilical artery pH being 7.246+/-0.081 vs. 7.244+/-0.106. All comparisons were not significant (NS). CONCLUSION: The combination of ephedrine and phenylephrine given as an intravenous bolus at the doses selected is not superior to ephedrine alone in preventing or treating hypotension in healthy parturients undergoing cesarean delivery.

Adult↗
PubMed2005

What's new and novel in obstetric anesthesia? Contributions from the 2003 scientific literature.

THE PREGNANT PATIENT: Age; maternal disease; prophylactic antibiotics; gastroesophageal reflux; obesity; starvation; genotyping; coagulopathy; infection; substance abuse; altered drug responses in pregnancy; physiological changes of pregnancy. THE FETUS: Fetal monitoring; intrauterine surgery. THE NEWBORN: Breastfeeding; maternal infection, fever, and neonatal sepsis evaluation. OBSTETRIC COMPLICATIONS: Embolic phenomena; hemorrhage; preeclampsia; preterm delivery. OBSTETRIC MANAGEMENT: External cephalic version and cervical cerclage; elective cesarean delivery; fetal malpresentation; vaginal birth after cesarean delivery; termination of pregnancy. OBSTETRIC ANESTHESIA: Analgesia for labor and delivery; anesthesia for cesarean delivery; anesthesia for short obstetric operations; complications of anesthesia. MISCELLANEOUS: Consent; ethics; history; labor support; websites/books/leaflets/journal announcements.

Adult↗
PubMed2001

Can estrogen influence the response to noxious stimuli?

STUDY OBJECTIVES: To evaluate estrogen-induced alternations in noxious stimuli response. DESIGN: Randomized, prospective, double-blind study. SETTINGS: Tertiary-care academic medical center. PATIENTS: 40 ASA physical status I and II women at the beginning and conclusion of an in vitro fertilization stimulation cycle. INTERVENTIONS: Stimuli were applied to the fingers of the dominant hand via a Basile Analgesy-Meter, which applied increasing pressure (g/cm(2)) in a continuous fashion, and ice water immersion. MEASUREMENTS: Serum hormonal concentrations and responses to noxious (pressure and cold thermal) stimuli were studied. MAIN RESULTS: Estrogen and progesterone concentrations changed from 377 +/- 323.42 pg/mL to 2078.05 +/- 1175.92 pg/mL (p < 0.001) and 1.20 +/- 0.56 to 1.03 +/- 0.35 ng/mL (p = NS), respectively. Although no significant difference was noted in the response to pressure (16.92 +/- 4.41 to 17.85 +/- 4.95 g/cm(2)), a significant reduction in the tolerance to ice water immersion (34.18 +/- 28.29 to 24.05 +/- 23.02 s) was observed. CONCLUSIONS: High estrogen concentrations are associated with significantly lower tolerance to cold, but not pressure stimuli.

Adult↗
PubMed2001

Transcutaneous electrical nerve stimulation does not augment epidural labor analgesia.

STUDY OBJECTIVE: To evaluate whether transcutaneous electrical nerve stimulation (TENS) can increase the quality and duration of an initiation dose of bupivacaine used for the establishment of epidural labor analgesia. DESIGN: Randomized, double-blind study. SETTING: Tertiary-care academic medical center. PATIENTS: 40 ASA physical status I and II parturients in early, active spontaneous labor with a singleton, vertex term fetus, and requesting analgesia. INTERVENTIONS: A standardized epidural technique with either an active or inactive TENS unit was performed. Before epidural placement, TENS intensity thresholds were determined with electrodes placed over the paraspinus muscles at T(10)-L(1), and S(2)-S(4); TENS settings for mode, cycle, and pulse width were standardized. MEASUREMENTS: Data were collected at timed intervals on pain as measured by visual analog scale (VAS), sensory level (pinprick), motor blockade (Bromage score), cervical dilation, and duration of analgesia. MAIN RESULTS: The duration of analgesia produced by the initial dose of epidural bupivacaine did not differ between groups (TENS turned off 82.3 +/- 26 [mean +/- SD] vs. TENS activated 80.7 +/- 40 min, p = 0.88). Kaplan-Meier survival analysis and Mantel-Cox log rank analysis showed no difference between the two treatments (p = 0.75). No difference in the quality of analgesia was observed between the two groups. CONCLUSIONS: In healthy laboring parturients, the application of a TENS unit did not alter the quality or duration of an initiation dose of bupivacaine utilized for the establishment of epidural labor analgesia.

Adult↗
PubMed2001

The mask avenger?

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Anesthesia, Conduction↗
PubMed2000

Transcutaneous electrical nerve stimulation does not augment combined spinal epidural labour analgesia.

PURPOSE: The spinal portion of the combined spinal epidural technique (CSE) provides dramatic but limited labour analgesia. Transcutaneous Electrical Nerve Stimulation (TENS) has been noted to modulate pain, in part by the frequency of stimulation chosen. Because nerve action potentials are blocked by local anesthetics in a frequency dependent manner, we speculated that a TENS unit could increase the quality and duration of the spinal portion of a CSE. METHODS: Forty parturients in active spontaneous labour, with a singleton, vertex, term fetus, requesting analgesia were enrolled in a randomized, double blind fashion to receive a standardized CSE with either an active or inactive TENS unit. Prior to CSE placement, TENS intensity thresholds were determined with electrodes placed on the paraspinus muscles at T10-L1, and S2-4; TENS settings for mode, cycle, and pulse width were standardized. Data were collected at timed intervals on pain (VAS), sensory level (pinprick), motor blockade (Bromage), cervical dilatation, and duration of analgesia, and at delivery on fetal and neonatal outcome. RESULTS: The duration of the spinal portion of the CSE did not differ between groups (TENS off 91.1+/-33 [mean +/- SD] vs. TENS on 83.1+/-28 min, P = .42). Kaplan-Meier survival analysis and Mantel-Cox log rank analysis showed no difference between the two treatments (P = .28). Analgesia was comparable throughout the first hour of spinal analgesia. CONCLUSION: In healthy labouring parturients, the application of a TENS unit did not alter the quality or duration of labour analgesia provided by the spinal portion of CSE analgesia.

Adult↗
PubMed2000

Hemodynamic effects of simultaneous administration of intravenous ephedrine and spinal anesthesia for cesarean delivery.

STUDY OBJECTIVE: To evaluate the hemodynamic effects of an intravenous (IV) ephedrine bolus given simultaneously with spinal anesthesia for cesarean delivery. DESIGN: Randomized, prospective, double-blind study. SETTING: Tertiary-care academic medical center. PATIENTS: 40 ASA physical status I and II nonlaboring women undergoing elective cesarean delivery of term, uncomplicated, singleton pregnancies. INTERVENTIONS: After a 10 mL/kg IV lactated Ringers bolus given over 15 minutes, patients simultaneously received an IV dose of 2 mL (10 mg) ephedrine or 2 mL saline, and an intrathecal dose of 12 mg (1.6 mL 0.75%) bupivacaine with 10 microg of fentanyl. Hypotension, defined as a 20% decrease in mean arterial pressure (MAP), was treated with 10-mg IV doses of ephedrine. MEASUREMENTS: Hemodynamic (heart rate and MAP) and non-invasive thoracic impedance (cardiac index, stroke index, and systemic vascular resistance index) measurements at baseline and at 1-minute intervals until the time of delivery. Total fluid, supplemental ephedrine, and Apgar scores were recorded. Data were evaluated using analysis of variance (ANOVA), ANOVA for repeated measures, and Mann-Whitney U-tests where appropriate, with p < 0.05 considered significant. MAIN RESULTS: Significant changes from baseline in MAP, systemic vascular resistance index, heart rate, and cardiac index were observed in both groups after spinal anesthesia. However, there were no differences between the ephedrine and saline groups in the incidence and severity of change from the baseline. The overall incidence of hypotension was 70% in both groups. No difference in total fluid or supplemental ephedrine use was observed. CONCLUSIONS: 10 mg of IV ephedrine given at the time of spinal anesthesia, and after a 10 mL/kg lactated Ringers fluid bolus, does not diminish the incidence or severity of hypotension in parturients undergoing cesarean delivery.

Adult↗
PubMed2000

Alternative medicine use in presurgical patients.

BACKGROUND: A dramatic increase in the use of complementary and alternative medicines has been observed. The use of such remedies in the presurgical population has implications for the anesthesiologist because of the potential for drug interactions, side effects, and medical liability. This study was undertaken to quantify the use of herbal remedies and vitamins in the presurgical population of a large tertiary care center. METHODS: A one-page questionnaire was distributed to all patients presenting for evaluation in the preoperative clinic over an 11-week period. Patients answered questions regarding use of prescription and nonprescription medications, herbal remedies, and vitamins. RESULTS: Twenty-two percent of presurgical patients reported the use of herbal remedies, and 51% used vitamins. Women and patients aged 40-60 yr were more likely to use herbal medicines. Over-the-counter medication use was strongly associated with herbal preparation use. The most commonly used compounds, from highest to lowest, included echinacea, gingko biloba, St. John's wort, garlic, and ginseng. CONCLUSIONS: Alternative medicine use is common in the preoperative period.

Adult↗
PubMed1999

Anesthesia for in vitro fertilization: the addition of fentanyl to 1.5% lidocaine.

UNLABELLED: Ultrasonically guided transvaginal oocyte retrieval is relatively short procedure that is performed on an out-patient basis. The optimal anesthetic technique should allow good surgical anesthesia with minimal side effects, a short recovery time, and, if possible, a high rate of successful pregnancy. Spinal anesthesia is often used in this institution, as well as many others, for this procedure. The addition of fentanyl may be effective for both intraoperative and postoperative pain relief. We assessed the effect of adding fentanyl to 1.5% lidocaine in women undergoing ultrasonically guided oocyte retrieval. Seventy-eight women were randomized to receive 45 mg of hyperbaric 1.5% lidocaine with or without 10 microg of fentanyl. Visual analog scale (VAS) pain scores were lower in the operating room (OR) (P < 0.05) and postanesthesia care unit (PACU) (P < 0.0005) for the group that received fentanyl. In addition, the amount of narcotic required in the PACU was less in the fentanyl group (P < 0.005). There was no difference in VAS scores the evening of or 24 h after the procedure. The amount of analgesics and narcotics required after discharge was the same for both groups. Timed variables, such as time to urination, ambulation, and discharge, were the same for both groups of women. The addition of fentanyl to lidocaine for transvaginal oocyte retrieval results in a more comfortable patient in the OR and PACU. IMPLICATIONS: This study demonstrates that when fentanyl is added to a local anesthetic, lidocaine, with spinal anesthesia for egg retrieval procedures, patients are more comfortable during the procedure compared with those who receive lidocaine alone. In addition, the narcotic requirements of patients are less in the postanesthesia care unit.

Adult↗
PubMed1999

Measurements of maternal protein binding of bupivacaine throughout pregnancy.

UNLABELLED: Pregnancy-related decreases in protein binding may contribute to altered effects of local anesthetics in the parturient. Previous studies have measured protein binding of bupivacaine in term parturients; the current study defines the ratio of bound-to-free bupivacaine throughout gestation at both therapeutic and toxic systemic concentrations of bupivacaine. Venous samples were obtained from 81 women, including 70 parturients, ranging from 7 to 42 wk of gestation and 11 nonpregnant controls. The percent bound bupivacaine at a fixed concentration was determined for each sample at both therapeutic (1 microg/mL) and toxic (5 microg/mL) concentrations using an ultrafiltration technique. Albumin and alpha-1-glycoprotein levels were also measured. Linear regression analysis showed a significant increase in concentration of free bupivacaine throughout gestation at the 5-microg/mL concentration, corresponding to a decrease demonstrated in both albumin and alpha-1-glycoprotein levels. A similar correlation was not found at the 1-microg/mL concentration. Although the relative magnitude of these changes is small, the relative change in free drug throughout gestation is large. Protein binding is only one of several mechanisms that may influence the susceptibility to local anesthetic toxicity in the parturient; however, its relative importance remains unclear. IMPLICATIONS: When venous samples taken from pregnant women were mixed with 5 microg/ml bupivacaine and analyzed, an increase in the free fraction of drug was seen with increasing gestational age, corresponding to decreases in alpha-1-glycoprotein and albumin.

Analysis of Variance↗
PubMed1999

Clinical effects and maternal and fetal plasma concentrations of 0.5% epidural levobupivacaine versus bupivacaine for cesarean delivery.

BACKGROUND: Bupivacaine exists as a mixture of two enantiomers, levobupivacaine and dexbupivacaine. Data suggest that levobupivacaine has equal local anesthetic potency, with reduced potential for central nervous system and cardiovascular toxicity. The present study compares the efficacy of 0.5% levobupivacaine with 0.5% bupivacaine for epidural anesthesia in parturients undergoing elective cesarean delivery. METHODS: Sixty healthy obstetric patients undergoing elective cesarean delivery with epidural anesthesia completed the study. Patients were randomized to receive 30 ml of either 0.5% levobupivacaine or 0.5% bupivacaine in a double-blind fashion. The efficacy endpoint measures included onset, offset, and quality of anesthesia. Neonatal blood gas analyses, Apgar score determinations, and neurobehavioral examinations were performed. Venous samples for pharmacokinetic studies and serial electrocardiograms were obtained in 10 patients in each group. RESULTS: Levels of sensory block, motor block, muscle relaxation, and overall quality of anesthesia did not differ between groups. The frequency of hypotension was 84.4% in the levobupivacaine group and 100% for the bupivacaine group (P < or = 0.053). No significant difference in observed maximum concentration of drug after dosing or area under the plasma drug concentration versus time curve were seen. The maximum concentrations were 1.017 and 1.053 microg/ml, and the areas were 4.082 and 3.765 h(microg/ml) for the levobupivacaine and bupivacaine groups, respectively. Umbilical vein-to-maternal vein ratios were 0.303 for the levobupivacaine group and 0.254 for the bupivacaine group. CONCLUSIONS: The use of epidural 0.5% levobupivacaine for cesarean delivery results in equally efficacious anesthesia compared with 0.5% bupivacaine. Pharmacokinetic parameters were similar in the two groups.

Adult↗