Epidurals placed during labour can be of use when manual removal of a retained placenta is necessary. We report a case of a scratching sensation in the ear and hypotension after a bolus of 4ml ropivacaine 7.5% in a previous sited epidural catheter. There was no loss of consciousness and the hypotension was treated with a bolus of ephedrine.

The severity of a possible local anaesthetic systemic toxicity was assessed employing the ABCD approach: apart from the brief episode of hypotension and the mild neurological symptoms, no severe symptoms were identified, thus no further treatment was warranted using an antidote. Aspiration of blood in the epidural catheter was seen and confirmed anaesthetic toxicity as most plausible cause.

After induction using a rapid sequence induction with placement of endotracheal tube, the surgical procedure was performed without any major postoperative issues.

In conclusion, it is important to check position and effectiveness when using a previously sited epidural catheter. Preferably a standardised approach using clinical information, patient’s account and some sort of test dose.

Introduction Epidurals placed during labour can be of use when manual removal of a retained placenta is necessary or when conversion to C-section is necessary. Several strategies exist to detect intravascular intrathecal or subdural epidural catheter misplacement. However a functional epidural catheter can migrate into an epidural vessel.

Patient Information A 37-year old parturient with no medical history was admitted for PPROM at 36 weeks of gestation and a dilation of 3–4cm. An epidural catheter was placed by a colleague anaesthetist and a continuous rate of 4 ml ropivacaine 0.16% was started, with an optional bolus of 3 ml with a lockout of ten minutes. Thirty minutes after placement of the epidural catheter the new-born was delivered and the epidural infusion was stopped. Due to a retained placenta the patient was booked for a manual placenta removal in the operating theatre.

With an unknown COVID status, no significant medical history (G4P3A0) and a previously sited epidural catheter the decision was made to perform the procedure under epidural anaesthesia. After an injection of 4ml of a 7.5% ropivacaine solution, the patient reported a scratching sensation in the ears followed by dizziness and hypotension of 66/45 mm Hg . The injection was immediately ceased and the anaesthetist attempted to aspirate the injected solution via the epidural catheter which showed blood in the epidural catheter.

Diagnostic and therapeutic management The anaesthetist assessed the patient employing the ABCD approach as suggested in the BARA guidelines regarding a possible local anaesthetic systemic toxicity (LAST)¹ and determined that apart from a brief hypotensive episode (blood pressure of 66/45 mmHg with a mean of 55mmHg) and the mild neurological symptoms (scratching sensation in combination with dizziness), there were no other (severe) symptoms reported.

Although the patient in this case presents itself with atypical symptoms i.e. a scratching sensation in the first place followed by dizziness, the timing of the symptoms alerted the anaesthetist to suspect LAST and cease the epidural injection and follow-up with an ABCD approach to further assess the severity of possible LAST.

Prodromal clinical signs of LAST include perioral numbness, tinnitus, agitation, dysarthria and confusion; which can deteriorate into more severe symptoms that warrant (early) treatment with the antidote (Intralipid®) as stated by the aforementioned BARA guidelines. Since the patient remained hemodynamically stable after the event in the absence of any severe (neurologic) symptoms, no further treatment was deemed necessary and the procedure was performed under general anaesthesia with a rapid sequence induction and endotracheal intubation. Patient was postoperatively discharged from the postoperative anaesthesia care unit (PACU) without any major issues.

Discussion This case illustrates how a previously sited epidural catheter doesn’t guarantee an evident viable mean for anaesthesia. A standardised approach is necessary to check whether the epidural catheter is (still) correctly positioned before using it for an epidural anaesthesia.

Firstly the importance of documentation needs to be highlighted as well, since a previous account of an ineffective epidural catheter could already indicate a possible malposition; in this case apart from basic documentation there was no description of ineffective analgesia nor any evidence of a misplaced catheter. The aforementioned elements have been outlined as well as recommendations for effective documentation in regional anaesthesia in a recent publication.²Secondly after a period of administered epidural analgesia, a brief clinical exam could be used to assess the effectiveness in relation to possible sensorimotor block.

Finally a test dose can be employed to rule out if the catheter is in an intravenous or intrathecal position and even in rare cases that a previously sited one doesn’t migrate in such a position which has been reported.³ What seems to be trivial, isn’t common practice according to a survey among British obstetric anaesthetists regarding an epidural top-up for an urgent C-section with a previously sited catheter.⁴

However the epidural test dose has been a source of controversy for a long period, the classical regime of 45–60mg of lidocaine or 7–15 bupivacaine in combination with 15µg of epinephrine^5–8 has several limitations for example the possible detrimental effects of epinephrine on the placental perfusion and the possible false positive result for intravenous placement attributed to the maternal heart rate variability during labour.

The lack of prospective randomised trials regarding an epidural test dose regimen in parturient patients has been addressed in a review published in 2009,⁹ whereas a recent review in 2019 points out that there is still no consensus on the employment of a test dose regimen and steers away from the test dose altogether in favour of a fractionated regimen of the therapeutic dose.¹⁰

In conclusion, this case illustrates the importance of a standardised approach to control for epidural catheter misplacement due to the possible severe consequences of inadvertent intravenous injection of local anaesthetics. This approach should encompass a thorough and reliable account of the functionality of the epidural catheter by the anaesthetist who placed it initially as well as a clinical exam and possible test dose regimen before using a previously sited catheter. Regarding the test dose regimen, there still is no consensus, particularly in the parturient, which perhaps might be a subject of further investigations aiming to provide a suitable protocol for confirming correct catheter placement in obstetric patients receiving epidural anaesthesia.

References

1. Desmet M, Bindelle S, Breebaart MB, Camerlynck H, Casaer S, Fourneau K, Gautier P, Goffin P, Lecoq JP, Lenders I, Leunen I, Van Aken D, Van Houwe P, Van Hooreweghe S, Vermeylen K, Sermeus L. Guidelines for the safe clinical practice of peripheral nerve blocks in the adult patient. Acta Anaesthesiologica Belgica 2020;71:3, p.151–161.

2. Ahmed HM, Atterton BP, Crowe GG, et al. Recommendations for effective documentation in regional anesthesia: an expert panel Delphi consensus project. Regional Anesthesia & Pain Medicine Published Online First: 22 February 2022. doi:10.1136/rapm-2021-103136

3. Spence A. Lipid reversal of central nervous system symptoms of bupivacaine toxicity. Anesthesiology 2007;107:516–517.

4. Gardner IC, Kinsella SM. Obstetric epidural test dose: a survey of the UK practice. Int J Obstet Anesth 2004;14:96–103.

5. Moore DC, Batra MS. The components of an effective test dose prior to epidural block. Anesthesiology 1981;55:693–696.

6. Abraham RA, Harris AP, Maxwell LG, Kaplow S. The efficacy of 1.5% lidocaine with 7.5% dextrose and epinephrine as an epidural test dose for obstetrics. Anesthesiology 1986;64:116–119.

7. Scott DB. Test doses in extradural block. Br J Anaesth 1988;61:129–130.

8. D’Angelo R, Thomas JA. Regional anesthesia in obstetrics. In: Palmer CM, D’Angelo R, Peach MJ, editors. Handbook of obstetric anesthesia. Oxford, UK: BIOS Scientific Publishers Limited; 2002. p.47–48.

9. Camorcia M. Testing the epidural catheter. Curr Opin Anaesthesiol 2009;22:3, p.336–340.

10. Massoth C, Wenk M. Epidural test dose in obstetric patients: should we still use it? Curr Opin Anaesthesiol 2019;32:3, p.263–267.