1.1 Remifentanil is a short acting synthetic opioid which is commonly used for Patient Controlled Analgesia in labour1. It has an onset time of approximately 60-90 seconds and half-life of approximately 5 minutes in adults2.

1.2 Remifentanil is broken down by esterases in the maternal and fetal blood and tissues³. The product of this degradation is almost entirely inactive⁴. Therefore, there is no significant build-up of the drug in the maternal circulation. Although remifentanil freely crosses the placenta, metabolism within the term fetus is rapid. There is no evidence of worse neonatal outcomes following remifentanil PCA in labour⁵.

2.1 Remifentanil PCA should be considered for women in established labour who are requesting analgesia, but for whom epidural analgesia is contra-indicated. If a PCA is needed for analgesia for delivery following an intrauterine death (IUD), morphine PCA is the first line choice.

2.2 Contra-indications to epidural analgesia include:

• Some types of spinal surgery may contraindicate the use of epidural analgesia, make it more challenging to site, or make its effect suboptimal

• Generalised sepsis or localised infection over site of epidural insertion

• Coagulopathy (INR ≥ 1.4 and/or platelet count ≤ 80 x 10⁹. l^-1)

• Allergy to amide local anaesthetics

• Those in whom epidural analgesia has completely failed despite best efforts

3.1 Contraindications to remifentanil PCA include:

• Maternal refusal

• Allergy to remifentanil or related opioids (pethidine, fentanyl)

• < 36 weeks gestation

  • there is little in the literature on its use and safety profile in the pre-term infant, so remifentanil PCA will not be provided at this gestation

• Impaired conscious level

• Inability to provide one to one midwifery care

• Multiple pregnancy

• If pethidine has been administered, wait 4 hours after the pethidine before commencing

• Itching and dizziness

• Drowsiness / sedation; this is no more than with pethidine ⁶

• Nausea and vomiting; this is no more than with pethidine^6,7

• Reduction in S_pO₂, this is no more than with pethidine ⁸

• Maternal bradycardia and hypotension is known to occur with this drug, but is not recorded in studies of remifentanil PCA in labour

• Abnormal fetal heart rate (CTG), but a lower incidence of abnormal CTG compared to pethidine ⁸ (not statistically significant)

• The woman is admitted to labour ward with either a written plan for remifentanil PCA by a consultant anaesthetist, or she is requesting analgesia and has a known or suspected contra-indication to epidural

• Anaesthetist to discuss the decision to use the remifentanil PCA with the on-call anaesthetic consultant, duty obstetric registrar and coordinating midwife on labour ward before commencing

• Obtain written consent and inform the woman that it is an off-licence use for remifentanil

• Site a dedicated intravenous cannula (22G or 20G) in a site where the cannula is not prone to kinking, e.g. not in the ante-cubital fossa

• Anaesthetist to check the PCA programme on the dedicated remifentanil PCA pump (which is kept on labour ward), and to draw up and carefully label the remifentanil syringe

• Connect the PCA syringe to a PCA giving set with an anti-siphon valve and flush through. It is best to use the single PCA giving sets rather than ones with side ports

• A remifentanil PCA should not be initiated if the baseline SpO2 < 94%

• Connect the PCA giving set to a dedicated iv cannula and avoid flushing the cannula or giving other drugs or fluids through it

• Patient is to have one to one midwifery care whilst using remifentanil PCA

• Remifentanil 2mg reconstituted with sodium chloride or water for injection and made up to 50ml (concentration 40 micrograms/ml) in a 50ml BD Plastipak syringe

• 40 microgram bolus dose (1 ml bolus), this can be reduced to 20 or 30 microgram bolus if the patient does not tolerate the 40 microgram bolus or the anaesthetist feels this appropriate

• Dose delivery set to STAT

• Lockout 2 minutes

• No background infusion

• No 4-hour dose limit

• Anaesthetist to prescribe PCA, oxygen and antiemetics on chart on Epic.

• PCA can be prescribed under “remifentanil PCA for labour”

7.1 Maternal:

• Continuous:

  • Oxygen saturations via pulse oximeter, started before first bolus

  • Oxygen 1-2l/min to be given routinely through nasal cannula throughout

  • One-to-one midwifery care is essential at all times. The anaesthetist should be present for the first four presses of the PCA in case of desaturation

• Observations every 15 minutes for 1^st hour, then every 30 minutes (record on PCA Observation Chart):

  • Heart rate

  • Blood pressure

  • Respiratory rate (RR)

  • Sedation score (as per PCA Observation Chart)

  • Pain relief (as per PCA Observation Chart)

  • Continue to monitor for 30 minutes after discontinuation

7.2 Fetal:

• Continuous electronic fetal monitoring

• Systolic blood pressure <100mmHg - contact anaesthetist for review

• S_pO₂ < 94% for greater than 1 minute

  • Increase oxygen at 2-4 l/min via nasal cannulae or 6l/min via Hudson mask (aim for S_pO₂ > 94%) and contact anaesthetist

• Respiratory rate (RR) <8 breaths per minute or apnoea >10 seconds

  • Take away PCA handset until RR increases to >10 breaths per minute and verbally encourage the woman to breathe

• Loss of verbal contact or midwife concern

  • Take away PCA handset and contact anaesthetist

If any of the above, anaesthetist to consider reducing the bolus dose

• The woman must be cared for on 1 to 1 basis by midwifery staff. The woman should never be left on their own; a qualified member of staff should be in the room at all times. Remifentanil is a potent drug and occasionally patients can desaturate very rapidly.

• If the woman has received pethidine, she should avoid remifentanil PCA for 4 hours after pethidine administration to avoid respiratory impairment

• Patients must not become dehydrated. Consider intravenous maintenance fluids if at risk of dehydration. Dehydration may potentiate respiratory side effects

• The anaesthetist on duty must ensure any woman with remifentanil PCA must be handed over to on-coming anaesthetic staff

• Patient may use Entonox and TENS in addition to PCA

• Patients should press the button just before or at the start of the contraction

• HANDSET IS ONLY TO BE USED BY THE PATIENT (no partner/ midwife controlled analgesia)

• Anaesthetist only to change remifentanil syringes and make changes to the PCA settings

• The woman’s mobility will be affected by the continuous monitoring, oxygen therapy and the potential to become drowsy. Patients should be looked after in bed whilst on remifentanil. They may go to the toilet if they do not press the PCA button for 5 minutes beforehand, and have two members of staff help them to the toilet, one of which stays in the toilet with the patient. The patient must not press the button again until they are back in bed. They should stay in bed if they still require oxygen or are drowsy

• The PCA can be used during delivery of the baby

• Use remifentanil PCA cautiously in morbidly obese women as they can desaturate easily. Consider a lower starting bolus dose and review regularly

• Always remove the dedicated remifentanil cannula without flushing it as soon as the PCA is finished to avoid an accidental bolus

• The anaesthetist setting up the pump should have received training on remifentanil PCA for labour. If not, please ask a member of the anaesthetic team who has had the appropriate training to help

• As well as the cannula for administration of remifentanil PCA, all patients should have a separate 16G Grey cannula placed

• Frimley:

• There will be a dedicated box on labour ward that contains everything required to run the PCA: the single PCA giving sets, protocol, patient information leaflets and audit forms, and the PCA pump next to the box

• Wexham:

  • The dedicated remifentanil PCA pump is available in the anaesthetic department along with the PCA giving set and the protocol and patient leaflets. These can also be printed from the intranet.

• Inadequate analgesia:

• Remifentanil PCA will reduce labour pain but not completely. Women experiencing unsatisfactory analgesia should be offered Entonox if they are not already using this. It may be that they are not co-ordinating the use of the PCA with their contractions, bearing in mind that a bolus will take 2-3 minutes to achieve peak effect and the PCA may need to be used between contractions

1. Saravanakumar, K., Garstang, J. S. and Hasan, K. (2007) ‘Intravenous patient-controlled analgesia for labour: a survey of UK practice’, International Journal of Obstetric Anesthesia, 16(3), pp. 221-225. Available at: https://doi.org/10.1016/j.ijoa.2007.01.010 (Accessed: 25 March).

2. Glass, P. S. et al. (1993) ‘Preliminary pharmacokinetics and pharmacodynamics of an ultra-short-acting opioid: Remifentanil (GI87084B)’, Anesthesia and Analgesia, 77(5), pp. 1031–1040. Available at: https://doi.org/10.1213/00000539-199311000-00028 (Accessed: 25 march 2025).

3. Ross, A. K. et al. (2001) ‘Pharmacokinetics of remifentanil in anesthetised pediatric patients undergoing elective surgery or diagnostic procedures’, Anesthesia and Analgesia, 93(6), pp. 1393-1401. Available at: https://doi.org/10.1097/00000539-200112000-00008 (Accessed: 25 March 2025).

4. Wilhelm, W. et al. (2003) ‘Remifentanil: An update’, Anaesthesist, 52(6), pp. 473–494. Available at: https://doi.org/10.1007/s00101-003-0540-9 (Accessed: 25 March 2025).

5. Kan, R. E. et al. (1998) ‘Intravenous remifentanil: placental transfer, maternal and neonatal effects’, Anesthesiology, 88(6), pp. 1467–1474. Available at: https://doi.org/10.1097/00000542-199806000-00008 (Accessed: 25 March 2025).

6. Blair, J. M. et al. (2005) ‘Patient controlled analgesia for labour: a comparison of remifentanil with pethidine’ Anaesthesia, 60(1), pp. 22-27. Available at: https://doi.org/10.1111/j.1365-2044.2004.03975.x (Accessed: 25 March 2025).

7. Thurlow, et al. ‘Remifentanil by patient-controlled analgesia compared with intramuscular meperidine for pain relief in labour’ British Journal of Anaesthesia, 88(3), pp. 374-378. Available at: https://doi.org/10.1111/j.1365-2044.2004.03975.x (Accessed: 25 March 2025).

8. Welzing, L. et al. (2011) ‘Remifentanil Degradation in Umbilical Cord Blood of Preterm Infants’, Anesthesiology, 114(3), pp. 570-577. Available at: https://doi.org/10.1097/aln.0b013e318204e043 (Accessed: 25 March 2025).

9. Obstetric Anaesthetists' Association (2025) Obstetric Anaesthetists' Association. Available at: https://www.oaa-anaes.ac.uk/ (Accessed: 25 March 2025).

This guideline has been registered with the Trust. However, clinical guidelines are guidelines only. The interpretation and application of clinical guidelines will remain the responsibility of the individual clinician. If in doubt, contact a senior colleague or expert. Caution is advised when using guidelines after the review date.
This guideline is for use in Frimley Health NHS Foundation Trust hospitals only. Any use outside this location will not be supported by the Trust and will be at the risk of the individual using it.

Version Control Sheet

Related Documents

None