Search

Background/purpose: Enhanced recovery after surgery (ERAS) is a growing tendency in modern perioperative period management, but no protocol has been established for a strategy that optimally facilitates rapid recovery from anesthesia. We hypothesized that applying a total intravenous anesthesia (TIVA) method to the response surface model (RSM) would allow prediction of the emergence and endotracheal tube extubation in cases undergoing video-assisted thoracotomy surgery (VATS)., Methods: Thirty patients who were scheduled to undergo VATs under TIVA were enrolled. Pharmacokinetic profiles were calculated using a Tivatrainer. Emergence from anesthesia was observed and the exact time point of the regained response (RR) was recorded. The effect of concentration was analyzed and applied to a response surface model., Results: The cumulative prediction curve of the RR was closer to the 50% probability as set by the OAA/S ≥ 4 than by the OAA/S ≥ 2 model. The median, averages, and standard deviations of the time differences were 14.5, 22.05 ± 19.23 min for the OAA/S ≥2 model and 10.4, 14.26 ± 10.40 min for the OAA/S ≥ 4 model., Conclusion: The OAA/S ≥ 4 model could identify the target concentration in propofol-remifentanil pairs that predicted the time of emergence from VATS in 10 min. Our results indicate that RSM can be used to derive an ERAS protocol for VATS under TIVA. Further studies should investigate application of RSM to predict ERAS for various types of procedures., (Copyright © 2019 Formosan Medical Association. Published by Elsevier B.V. All rights reserved.)

Background: Sedation for esophagogastroduodenoscopy (EGD) and colonoscopy is characterized by rapid patient induction and emergence. The drugs midazolam and alfentanil have long been used for procedural sedation; however, the relationship between plasma or effect-site concentrations (Cp or Ce, respectively) and emergence remains unclear. The aim of this study is to develop patient wake-up prediction models for both Cp and Ce using response surface modeling, a pharmacodynamics tool for assessing patients' responses., Methods: The Observer's Alertness/Sedation (OAA/S) score was used to monitor sedation depth during the examinations. Concentration pairs of midazolam and alfentanil were calculated for each of Cp and Ce using pharmacokinetic simulation software. Response surface models were developed using the Greco construct. Temporal analysis was done by comparing model-predicted wake-up time with true patient wake-up time., Results: Thirty-three patients with an average body mass index of 21.85 ± 2.3 kg/m 2 were pooled for analysis. The average duration of examination were 2.9 ± 1.4 min for EGD and 6.6 ± 2.7 min for colonoscopy. Seventy-five concentration pairs of midazolam and alfentanil were obtained for each Cp and Ce. The Cp-based Greco response surface model showed significant synergy between midazolam and alfentanil and was a better predictor of patient wake-up time, with an average deviation of 1.0 ± 3.9 min, while the Ce model show time deviation greater than 20 min., Conclusion: The early phases of drug distribution are unique and complicated by nonsteady-state concentrations, and our study revealed that Ce-based wake-up time prediction is more difficult under these circumstances., (Copyright © 2018. Published by Elsevier B.V.)

Background/purpose: The Stagnara wake-up test assesses neurological deficits during scoliosis surgery, and response surface interaction models for opioids and inhaled agents predicts anesthetic drug effects. We hypothesized that there is an optimal desflurane-fentanyl dosing regimen that can provide a faster and more predictable wake-up time, while also ensuring adequate analgesia during wake-up testing., Methods: Twenty-three American Society of Anesthesiologists Class I-II scoliosis patients who received desflurane-fentanyl anesthetic regimens were enrolled in this posthoc study, and their intraoperative drug administration data were collected retrospectively. Desflurane and fentanyl effect site concentrations were calculated using pharmacokinetic models, and converted to equivalent remifentanil-sevoflurane concentrations., Results: Results were fitted into Greco models for predicting the probability of an Observers Assessment of Alertness/Sedation score of <2. At time of wake-up, the models correctly predicted the probability that patients would respond to voice prompts and prodding was approximately 50%. The probability of pain intensity was distributed between 50% and 95%, indicating a low degree of pain at emergence. When comparing subgroups defined by calculated effect-site fentanyl concentrations, the wake-up time in the intermediate concentration group was significantly shorter than that in the high concentration group (p = 0.024)., Conclusion: This study provides evidence that desflurane-fentanyl-based anesthesia is conducive to rapid emergence followed by an immediate neurological evaluation. Intermediate fentanyl effect-site concentrations (1-2 ng/mL) at time of wake-up were associated with good balance between rapid emergence and adequate analgesia. Furthermore, we believe that generalizing response surface models to a variety of inhalation agent-opioid combinations using simple relative potency relationships is possible and practical., (Copyright © 2016. Published by Elsevier B.V.)

Perioperative mortality in patients with Eisenmenger's syndrome is very high, particularly following cesarean section. This case report describes the successful use of low-dose bupivacaine-fentanyl spinal anesthesia for lower extremity surgery in a nonparturient with Eisenmenger's syndrome. A 21-year-old woman with Eisenmenger's syndrome was scheduled to have a fibular head tumor excision. After placement of routine monitor and an arterial line, we inserted an epidural catheter at the L3-L4 interspace to cover a potential inadequate block and then we administered 6 mg of hyperbaric bupivacaine 0.5% with 20 microg of fentanyl intrathecally via a 27-gauge needle at the L4-L5 interspace. There were no hypotension, respiratory depression, hypoxemia, and other severe hemodynamic alterations. No drug was administered via the epidural catheter in the 2-hour operative period and the postoperative course was uneventful. Therefore, we propose that intrathecal opioids combined with local anesthetics may be an alternative anesthetic method in patients with Eisenmenger's syndrome.

Background/purpose: Intravenous patient-controlled analgesia (IVPCA) is one of the most widely used postoperative analgesic methods. Many factors could affect the total analgesic consumption of IVPCA. This retrospective study investigated the relationship between patient characteristics and total morphine consumption during a 3-day course of postoperative IVPCA., Methods: Patients receiving surgery under general anesthesia with postoperative IVPCA for 3 days during the period between January 2002 and December 2003 were included. Patient data including age, sex, weight, height, body mass index (BMI), operation type and site were collected. Total morphine consumption was recorded at the end of the 3-day IVPCA course. Stepwise regression analyses were conducted to select factors significantly associated with morphine consumption. Stratified analyses were also conducted among different surgical, BMI and age subgroups., Results: A total of 1308 patients (646 men, 662 women) were included in the analysis. For all operations, weight, age, procedures involving malignant disease, and surgical sites were significantly associated with total morphine consumption. The R and adjusted R2 values of the selected model were 0.509 and 0.256, respectively. Weight was the only common factor among all stratified analyses (all p < 0.001). Age was negatively correlated with morphine consumption. Gender was not a significant factor except in lower abdominal operations. Height was not associated with total morphine consumption. BMI status was not significantly associated with components of the selected factors., Conclusion: This study demonstrated that weight and surgical sites significantly influence total IVPCA requirements. The effect of surgical sites should be considered when evaluating the influence of demographic characteristics on IVPCA demand.