Anesth Analg 2007;104:1616-1617
© 2007 International Anesthesia Research Society
doi: 10.1213/01.ane.0000260645.48266.f1
LETTER TO THE EDITOR
Section Editor:
Lawrence Saidman
Use of Remifentanil for Labor Analgesia: The Good and the Bad
Joel Waring, MD,
Sohail K. Mahboobi, MD,
Kalpana Tyagaraj, MD, and
David Eddi, MD
Department of Anesthesiology; Maimonides Medical Center; Brooklyn, New York; joelwaring{at}hotmail.com
To the Editor:
Remifentanil has been successfully used for labor analgesia for parturients who request analgesia other than epidural block or who cannot receive neuraxial analgesia because of pre-existing conditions that include anticoagulant therapy or coagulation disorders (1–4). Controversy still exists regarding the mode of administration and appropriate dosing. Three studies have shown inconsistent efficacy with IVPCA/bolus dosing and continuous effusions (3–5). Volmanen et al. (3) reported successful use of IVPCA remifentanil for analgesia during the first stage of labor; however, they did not continue the study into the second stage. Olufolabi et al. (5) reported the inability to achieve effective analgesia with bolus dosing of remifentanil in four consecutive patients without significant maternal opioid-related side effects forcing him to abandon his investigation. Owen et al. (4) reports the successful use of a continuous remifentanil infusion for 34 h without significant side effects in a single patient. There are no large randomized control studies to help guide the use of remifentanil for labor analgesia. We are reporting use of remifentanil for labor analgesia in two patients in whom neuraxial anesthesia was contraindicated.
The first patient was a 33-yr-old female at 40 wk gestation with Factor XI deficiency, admitted in early labor. Remifentanil PCA was offered as an alternative for pain management and the initial PCA settings were PCA dose 20 µg, delay lockout 6 min, and no baseline infusion. On the basis of the intensity of the pain and the frequency of the contractions, the PCA dose was gradually increased to a maximum of 70 µg and delay lockout of 3 min. The patient was continuously monitored with NIBP and pulse oximetry and received supplemental oxygen. Delivery occurred after 11 h of remifentanil IVPCA, without complications or opioid-related side effects, and the patient expressed satisfaction with her pain relief. APGAR scores at 1 and 5 min were 9 and 9. Umbilical cord gases were normal at time of delivery.
The second patient was 38-yr-old with von Willebrand’s disease, in active labor. A continuous remifentanil infusion at 0.025 µg · kg–1 · min–1 for 15 min was begun and titrated according to the pain intensity by an anesthesiologist at the bedside. At a rate of 0.05 µg · kg–1 · min–1 for 10 min her pain score, with contractions, was still 10/10 and when the rate was increased to 0.1 µg · kg–1 · min–1 her pain score decreased to 6/10. She was continuously monitored using NIBP and pulse oximetry and received supplemental oxygen. However, shortly after the first contraction at the 0.1 µg · kg–1 · min–1 rate, and approximately 3 min after the increase, she became apneic. The infusion was stopped and her lungs ventilated via bag-mask. The initial period of apnea was accompanied by a fetal heart rate decrease into the 60’s. Simultaneously, as bag-mask ventilation was initiated, left uterine displacement and fetal scalp massage were performed in effort to restore placental blood flow and increase the fetal heart rate. The patient was taken to the operating room (OR) for possible emergency Cesarean delivery. Naloxone was readily available; however, after initial airway maneuvers the lungs were easily ventilated and the decision was made to administer naloxone on arrival to the OR if needed. On arrival to the OR the patient regained consciousness, was spontaneously breathing with a room air Spo2 of 96%, and fetal heart tracings returned to baseline. Nevertheless the obstetrician proceeded with an emergency Cesarean delivery because of the severity of the fetal decelerations during the initial period of apnea. Although the fetal heart rate decelerations were likely due to the episode of maternal apnea, the obstetrician could not rule out the presence of uteroplacental insufficiency. General endotracheal anesthesia was administered uneventfully. Baby’s APGAR scores were 9/9 with no evidence of acidosis in the cord blood.
These cases illustrate that both the nature of the pain (episodic versus continuous) and the potency and rapidity of action of remifentanil cause sudden respiratory depression during IV PCA. There appears to be wide variations in the dose required for effective labor analgesia, making the therapeutic window surprisingly narrow (1,3,4). The fast onset of action and rapid clearance are properties that make remifentanil an ideal drug for PCA use, but its potency may cause serious side effects when used as a continuous infusion in patients in labor with episodic pain (2). Large-scale studies are needed before it can be safely recommended as standard mode of analgesia for obstetric patients.
REFERENCES
- Volmanen P, Akural E, Raudaskoski T, et al. Comparison of remifentanil and nitrous oxide in labour analgesia. Acta Anaesthesiol Scand 2005;49:453–8.[Web of Science][Medline]
- Evron S, Glezerman M, Sadan O, et al. Remifentanil: a novel systemic analgesic for labor pain. Anesth Analg 2005;100:233–8.[Abstract/Free Full Text]
- Volmanen P, Akural E, Raudaskoski T, Alahuhta S. Remifentanil in obstetric analgesia: a dose finding study. Anesth Analg 2002;94:771–3.[Free Full Text]
- Owen MD, Poss MJ, Dean LS, Harper MA. Prolonged intravenous remifentanil infusion for labor analgesia. Anesth Analg 2002;94:918–19.[Abstract/Free Full Text]
- Olufolabi AJ, Booth JV, Wakeling HG, et al. A preliminary investigation of remifentanil as a labor analgesic. Anesth Analg 2000;91:606–8.[Abstract/Free Full Text]
|
