Respiratory arrest in a parturient following intrathecal administration of fentanyl and bupivacaine as part of a combined spinal‐epidural analgesia for labour

The safety of the combined spinal epidural (CSE) technique for labour analgesia is well established. However, several authors have recently reported uncommon complications including aphasia [1], dysphagia [2], altered level of consciousness [3], high sensory block [4], respiratory depression [5], andrespiratory arrest [6] following induction of CSE for labour pain. I herein report a case of a healthy parturient who developed sudden respiratory arrest and required tracheal intubation following intrathecal injection of fentanyl 10 μg in combination with bupivacaine 2.5 mg as part of a CSE technique for pain relief in labour. A 26-year-old, 162 cm, 65 kg, gravida 4, para 2, healthy female at 39 weeks gestation was in labour and requested analgesia. She had no drug allergies and had had no previous anaesthetics prior anaesthesia. Her admission blood pressure was104/62 mmHg, heart rate 66beats.min−1 and respiratoryrate 17breaths.min−1. Fetal heart rate (FHR) was 140 beats.min−1 and reactive. The course of her pregnancy had been uneventful. No contra-indications to regional anaesthesia were identified and the patient consented to epidural analgesia. The epidural catheter insertion technique consisted of using the sitting position and a median approach at the L3-4 vertebral interspace. An 18-gauge Tuohy-Schliff epidural needle was introduced with the loss of resistance to saline technique and the epidural space was identified on the first attempt. A 20-gauge multi-orifice epidural catheter was inserted 5 cm into the epidural space. Aspiration from the epidural catheter was negative for blood and cerebro-spinal fluid (CSF). An epidural test dose consisting of 1.5% lidocaine 3 ml (45 mg) with epinephrine 1 : 200 000 (15 µg) was administered and was found to be negative for intravascular and subarachnoid catheter placement. Epidural analgesia consisted of an initial bolus, loading dose of 0.125% bupivacaine 10 ml with fentanyl 50 µg, followed by a maintenance continuous infusion of 0.1% bupivacaine with fentanyl 2 µg.ml−1 at the rate of 10 ml.h−1. However, over the next 2 h, two rescue boluses of 0.25% bupivacaine (45 mg total) with fentanyl (100 µg total) were required for breakthrough pain, providing no relief of labour pain. The epidural catheter wasremoved and the decision was made to proceed with the administration of CSE via a needle-through-needle technique at the L2-3 vertebral interspace. The technical aspects of epidural space identification were identical to those previously described. After an uneventful epidural needle placement (18-gauge Touhy-Schliff epidural needle on the first attempt), a 27-gauge Pencan needle was inserted inside the epidural needle. Following the appearance of CSF at the hub of the spinal needle, fentanyl 10 µg combined with bupivacaine 2.5 mg (1 ml of 0.25% solution) was injected into the intrathecal space. A 20-gauge multi-orifice epidural catheter was inserted 5 cm into the epidural space. Aspiration from the epidural catheter was negative for blood and CSF. The patient reported pain relief 2 min after the intrathecal injection. Approximately 4 min after the intrathecal injection when the anaesthetist was securing the epidural catheter with tape, the patient became increasingly somnolent with subsequent loss of consciousness and the development of apnoea. Pulse oximetry revealed progressive desaturation to 85% while blood pressure decreased to 75/40, and FHR decreased to 60 beats.min−1. Airway control with tracheal intubation was accomplished at the bedside within approximately 60 s. Following 2–3 min of positive pressure ventilation with100% oxygen, oxygen saturation returned to 100%, blood pressure increased to 104/60, and fetal bradycardia resolved with prompt returnto baseline (140 beats.min−1). The return of spontaneous respiration was reported in 5–6 min following trachealintubation, and approximately 12–13 min after intrathecal injection of fentanyl and bupivacaine. Four minutes later she regained consciousness, was alert and able to follow commands. The pinprick sensory level of analgesia was at T8. No signs of motor blockade were documented. The chest was clear to auscultation and vital signs remained stable. Chest X-ray and arterial blood gas analysis were normal. The patient did not require any further treatment and was extubated approximately 30 min after the episode of respiratory arrest. An epidural test dose, as described above, was administered 60 min later and was found to be negative for intravascular and subarachnoid catheter placement. Labour epidural analgesia consisted of a maintenance continuous infusion of0.1% bupivacaine with fentanyl 2 µg.ml−1 at the rate of 10 ml.h−1, and provided good pain relief for the rest of her labour. However, 3 h after the induction of CSE and respiratory arrest, Caesarean section was required for failure to progress. A T4 sensory level of anaesthesia, as documented by pinprick, was established with incremental doses of 2% lidocaine to a total of 18 ml (360 mg) and fentanyl 100 µg administered through an epidural catheter. An uneventful Caesarean delivery of a female fetus weighing 3500 g, who had Apgar scores of 9 and 10, after 1 and 5 min, respectively, was accomplished. When interviewed after the delivery, the patient had incomplete recall of the events leading to respiratory arrest, particularly recalling only sudden onset of 'sleepiness'. Her postoperative course was uneventful and she was discharged home on the fourth postoperative day. The time of onset of respiratory arrest in the patient described in this report is consistent with a reaction to intrathecal fentanyl administration. Extensivecephalad spread of fentanyl might have been facilitated by the volume of the epidural rescue boluses of bupivacaine with fentanyl (each 10 ml, for a total volume of 20 ml), given in addition to a continuous maintenance infusion (10 ml.h−1), which had been administered over 2 h prior to induction of CSE. Greenhalgh reported a similar case of an obstetric patient who had a respiratory arrest shortly after receiving intrathecal sufentanil and bupivacaine as part of a CSE technique for pain relief in labour [6]. The author of this report is not aware of any other reports documenting emergent, intrapartum anaesthetic management of a parturient developing sudden onset of respiratory arrest following induction of CSE with fentanyl and bupivacaine. In conclusion, this case adds one more piece of evidence that respiratory depression is now a recognised feature of intrathecal administration of lipid-soluble opioids for labour analgesia. Increased level of vigilance, appropriate monitoring of these patients and availability of resuscitation equipment are therefore necessary.