A desflurane and fentanyl dosing regimen for wake-up testing during scoliosis surgery: Implications for the time-course of emergence from anesthesia.
OBJECTIVE
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).


CONCLUSIONS
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.
Department of Anesthesiology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan, Republic of China.
Wei-Nung
WN
Teng
Department of Anesthesiology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan, Republic of China.
Mei-Yung
MY
Tsou
Department of Anesthesiology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan, Republic of China.
Pin-Tarng
PT
Chen
Department of Anesthesiology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan, Republic of China.
Jing-Yang
JY
Liou
Department of Biomedical Engineering, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, People's Republic of China.
Lu
L
Yu
Department of Anesthesiology and Biomedical Engineering, University of Utah, Salt Lake City, UT, USA.
Dwayne R
DR
Westenskow
Department of Anesthesiology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan, Republic of China. Electronic address: ckting2@gmail.com.
Chien-Kun
CK
Ting
D000293:Adolescent; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000758:Anesthesia; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D000077335:Desflurane; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage*; D006801:Humans; D007530:Isoflurane / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008297:Male; D011336:Probability; D012189:Retrospective Studies; D012600:Scoliosis / Q000601:surgery*; D055815:Young Adult
D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D000077335:Desflurane; D007530:Isoflurane; D005283:Fentanyl
desflurane; fentanyl; response surface; scoliosis surgery; wake-up testing