A Jost1, R Blagus2, B Ban3, M Kamenik4. 1. Department of Anaesthesiology, Intensive Care and Pain Management, General Hospital Celje, Celje, Slovenia. Electronic address: tonijost@gmail.com. 2. Institute for Biostatistics and Medical Informatics, Medical Faculty, University of Ljubljana, Ljubljana, Slovenia. 3. Department of Anaesthesiology, Intensive Care and Pain Management, General Hospital Celje, Celje, Slovenia. 4. Department of Anaesthesiology, Intensive Care and Pain Management, University Medical Centre Maribor, Maribor, Slovenia.
Abstract
BACKGROUND:Intravenous remifentanil has been described for patient-controlled analgesia in labour. Recently, the application of target-controlled infusion pumps with Minto's pharmacokinetic/pharmacodynamic model has been reported. Hypothetical effect-site remifentanil concentration during patient-controlled analgesia for labour has yet to be examined. The aim of this concept study was to explore characteristics of this parameter. METHODS: We performed a historical cohort study based on our previous randomised cross-over clinical trial and analysed hypothetical effect-site remifentanil concentration. Values at spontaneous vaginal delivery and Apgar scores were tested for correlation. The association between pain score and the corresponding effect-site remifentanil concentration before and after bolus administration, and their relative difference, was examined with a linear mixed-effects model, adjusted for other variables. RESULTS: A series of 23 parturients with uncomplicated singleton pregnancies were included. On average, effect-site remifentanil concentration was highest during the third quarter throughout our recordings (5.5ng/mL; maximum 15.8ng/mL). The mean (median) {IQR} [range] at spontaneous vaginal delivery (n=14) was 2.52 (1.32) {0.95-4.28} [0.65-6.88] ng/mL, all Apgar scores were >7, and no correlation was confirmed. A negative association between effect-site remifentanil concentration before bolus administration and pain score (scale 0-100) was observed (-3.9, 95% CI -5.16 to -2.61, P <0.01). CONCLUSIONS: The residual value of hypothetical effect-site remifentanil concentration before uterine contraction, at the beginning of bolus administration, predicted lower pain scores. Monitoring effect-site remifentanil concentration may be potentially useful when remifentanil is administered for labour analgesia. However, our results need to be confirmed with a pharmacokinetic model optimized for pregnant patients.
RCT Entities:
BACKGROUND: Intravenous remifentanil has been described for patient-controlled analgesia in labour. Recently, the application of target-controlled infusion pumps with Minto's pharmacokinetic/pharmacodynamic model has been reported. Hypothetical effect-site remifentanil concentration during patient-controlled analgesia for labour has yet to be examined. The aim of this concept study was to explore characteristics of this parameter. METHODS: We performed a historical cohort study based on our previous randomised cross-over clinical trial and analysed hypothetical effect-site remifentanil concentration. Values at spontaneous vaginal delivery and Apgar scores were tested for correlation. The association between pain score and the corresponding effect-site remifentanil concentration before and after bolus administration, and their relative difference, was examined with a linear mixed-effects model, adjusted for other variables. RESULTS: A series of 23 parturients with uncomplicated singleton pregnancies were included. On average, effect-site remifentanil concentration was highest during the third quarter throughout our recordings (5.5ng/mL; maximum 15.8ng/mL). The mean (median) {IQR} [range] at spontaneous vaginal delivery (n=14) was 2.52 (1.32) {0.95-4.28} [0.65-6.88] ng/mL, all Apgar scores were >7, and no correlation was confirmed. A negative association between effect-site remifentanil concentration before bolus administration and pain score (scale 0-100) was observed (-3.9, 95% CI -5.16 to -2.61, P <0.01). CONCLUSIONS: The residual value of hypothetical effect-site remifentanil concentration before uterine contraction, at the beginning of bolus administration, predicted lower pain scores. Monitoring effect-site remifentanil concentration may be potentially useful when remifentanil is administered for labour analgesia. However, our results need to be confirmed with a pharmacokinetic model optimized for pregnant patients.