Total spinal following labour epidural analgesia managed with non-invasive ventilation.
The patient has given her consent for the clinical details of her case to be published in a peer-reviewed medical journal.
A 30-year-old parturient (gravida 2, para 1) at 39 weeks gestation presented in labour at 4 cm cervical dilatation. Her previous delivery, under epidural anaesthesia, had been by emergency caesarean section due to suspected foetal compromise. She had a history of mild asthma which was currently managed with inhaled beclomethasone twice daily.
Epidural analgesia was requested shortly after admission. An 18 gauge Tuohy needle was inserted at the L3/4 interspace in the sitting position. The epidural space was located at 6 cm via loss-of-resistance to saline, and a closed-end epidural catheter with three lateral eyes was placed (5 cm inserted into the space). Aspiration of the catheter was negative and 5 ml of 0.25% bupivacaine (12.5 mg) was administered as a test dose.
By 20 minutes after insertion, a total of 15 ml of 0.25% bupivacaine (37.5 mg) had been administered in 5 ml increments, but the patient remained distressed by contractions, had a blood pressure of 115/70 mmHg and a Bromage score of 1. A further 5 ml (12.5 mg) of 0.25% bupivacaine was administered after a negative aspiration test. Fifteen minutes after this fourth dose, the patient stated "I cannot breathe". Chest auscultation was clear. Grip strength was intact but there was bilateral sensory loss to ice to C5. Motor block then rapidly progressed, with the patient only able to speak in whispers and unable to lift her head against gravity. Sensory block had progressed to C2. Catheter aspiration showed clear fluid with a glucose concentration of 5.7 mmol/l.
A Vision[R] Bi-level Positive Airway Pressure (BiPAP) mask/machine was applied and revealed tidal volumes of 50 to 60 ml prior to application of positive pressure. BiPAP was commenced with inspiratory positive airway pressure 6 cm[H.sub.2]O, expiratory positive airway pressure 4 cm [H.sub.2]O and inspired oxygen concentration (Fi[O.sub.2]) of 100%. All breaths were patient-triggered, producing tidal volumes of 600 to 700 ml at a respiratory rate of 18. Oxygen saturation (Sa[O.sub.2]) was 100% throughout and the BiPAP was well tolerated, the patient appearing less anxious and dyspnoeic. Motor function gradually returned and BiPAP was removed after 40 minutes. A further 50 minutes later the motor block had resolved completely but there was still sensory block to C7.
The parturient was subsequently transferred for caesarean section based on maternal request and slow progress of labour. Catheter aspiration still showed cerebrospinal fluid and the sensory block remained at C7 despite normal lower limb motor function. A total of 1.5 ml of 0.5% hyperbaric bupivacaine (7.5 mg) plus 15 [micro]g of fentanyl was administered via the intrathecal catheter and provided adequate intraoperative anaesthesia. A live female baby with Apgar scores of 9/10 at one and five minutes was delivered. The level of sensory block remained unchanged and motor block confined to the lower limbs throughout the operation.
The subarachnoid catheter was left in situ for 24 hours from the initial insertion time in an attempt to decrease the risk of post-dural puncture headache. Post-dural puncture headache did not develop and the patient was discharged home on the third postoperative day.
The use of non-invasive ventilation in this setting (ventilatory failure due to high neuraxial block) does not appear to be a common practice. The lack of significant alteration of haemodynamic parameters in this situation was also unusual. To the authors' knowledge, no other cases describing the use of non-invasive ventilation for high neuraxial block have been reported. There are many case reports in the literature describing intubation and ventilation (with subsequent emergency caesarean section) (2-4), and some reports of brief bag-and-mask ventilation with a 'watch and wait' approach (5-7). The duration of high block varies from 20 to 120 minutes in most cases reported.
Given the low incidence of 'total spinal' anaesthesia, the rate of invasive ventilation in this group is hard to determine. Jenkins (1) reported complications among 145,550 epidural techniques and observed nine cases of high neuraxial block, but no comment was made on the management of these blocks. Yentis (8) reviewed several series of epidural analgesia and/or anaesthesia, finding 16 cases of high neuraxial block within these series. Of these patients, 15 (93.8%) were managed by intubation and invasive ventilation.
Our institution provides access to a paediatric intensive care unit but not to an adult intensive care unit. Given the need for rapid patient monitoring and support and that the intervention was likely to be brief, it was considered safer and more efficient to transport the BiPAP machine from the paediatric intensive care unit to the patient, rather than transport the patient to the unit. Locating treatment within the delivery unit necessitated the provision of staff familiar with the use of non-invasive ventilation (in this case an anaesthetist and an intensive care nurse). However, this location had the advantages of constant cardiotocographic foetal monitoring and ready access to obstetric clinicians and midwives.
The minimum requirements to safely treat and monitor a parturient on non-invasive ventilation within a delivery unit setting include staff who are familiar with this method of ventilation, with the skills to initiate intubation and invasive ventilation if the parturient or foetus deteriorates, the ability to monitor both the parturient and foetus and the ready availability of a theatre should emergency caesarean section be required.
The use of non-invasive ventilation was well tolerated by this patient and facilitated the maintenance of adequate ventilatory function while the block subsided. It enabled the parturient to proceed to caesarean section with the use of subarachnoid anaesthesia at a later stage, rather than progress to emergency caesarean section under general anaesthesia, with its attendant potential maternal and neonatal risks.
Other situations in which non-invasive ventilation might be instituted within the delivery unit include the management of pulmonary oedema associated with either pre-eclampsia or an underlying maternal cardiac disorder. Non-invasive ventilation could act as a temporising measure during medical optimisation but would again require adequate staffing and facilities.
The potential risks associated with non-invasive ventilation in this situation include the risk of aspiration due to impaired airway reflexes, a potential increase in intragastric volume and the risk of impairing venous return due to increased intrathoracic pressures. These problems were minimised by maintenance of the patient in the sitting position, maintaining intravascular volume and using low ventilator pressures. Development of hypoxia or hypotension at any stage would have necessitated intubation, ventilation and emergency caesarean section due to the likelihood of foetal compromise.
Given the short duration of most reported cases of high block (usually less than one hour), it would appear that non-invasive ventilation provides an opportunity to avoid intubation, intermittent positive pressure ventilation and a caesarean section under general anaesthesia. The benefits of such an approach include avoidance of difficult intubation and the effects of general anaesthesia on both the parturient and the foetus, and the ability to modify the psychological impact of the adverse event on the mother. In our case, the patient reported a marked reduction in anxiety once BiPAP was applied and later reported a sense of relief that the caesarean section had been able to be performed under regional rather than general anaesthesia.
The clinical picture observed during the initial block may have represented a subdural catheter placement. The classical description of a subdural block is one of slow onset that extends higher than would be expected but with minimal motor or haemodynamic compromise (1,9). It has been postulated that following subdural catheter placement, subsequent entry of the catheter into the subarachnoid space occurs due to tearing of the arachnoid mater on administration of local anaesthetic (10). In this case, the first three doses may have been administered subdurally and this could explain the slow onset block without haemodynamic compromise. Then the administration of the fourth dose may have resulted in breach of the arachnoid mater, with subarachnoid spread of local anaesthetic producing the rapid dense motor block and respiratory compromise observed.
The case was atypical because the parturient maintained good haemodynamic stability, continued to trigger the BiPAP machine and displayed reassuring cardiotocographic features throughout, thus allowing the use of non-invasive ventilation without the need to progress to emergency caesarean section. The use of BiPAP in the delivery unit proved simple and quick to institute but required the presence of an anaesthetist at all times. Lack of familiarity with non-invasive ventilation among midwives also mandated the presence of an intensive care nurse. The pattern of block progression may have represented an initial subdural block followed by penetration of the arachnoid mater by the epidural catheter.
Accepted for publication on September 17, 2009.
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(3.) Caliskan E, Bodur H, Baykara N, Eren L, Yucesoy I. Bedside caesarean section due to total spinal block after epidural anesthesia for labor pain. Int J Obstet Anesth 2006; 15:87-88.
(4.) Abouleish E, Goldstein M. Migration of an extradural catheter into the subdural space. A case report. Br J Anaesth 1986; 58:1194-1197.
(5.) Ravindran RS, Bond VK, Tasch MD, Gupta CD, Luerssen TG. Prolonged neural blockade following regional analgesia with 2-chlorprocaine. Anesth Analg 1980; 59:447-451.
(6.) Kalil A. Unintended subdural injection: A complication of epidural anaesthesia. A case report. AANA Journal 2006; 74:207211.
(7.) Russell IF. Total Spinal or massive subdural? Anaesth Intensive Care 1983; 11:386-388.
(8.) Yentis SM, Dob DP. High regional block - the failed intubation of the new millenium? Int J Obstet Anesth 2001; 10:159-161.
(9.) Russell IF. Total spinal anaesthesia: the effects of spinal infusions. In: Reymolds F, ed. Epidural and spinal blockade in obstetrics. London: Balliere Tindall 1990. p. 107-120.
(10.) Reynolds F, Speedy HM. The subdural space: the third place to go astray. Anaesthesia 1990; 45:120-123.
A. P. GUTERRES *, M. J. NEWMAN [[dagger]]
Department of Women's Anaesthesia, Women's and Children's Hospital, Adelaide, South Australia, Australia
* M.B., B.S. (Adel.), Registrar.
[[dagger]] M.B., B.S., F.A.N.Z.C.A., Specialist Anaesthetist, Wakefield Anaesthetic Group.
Address for correspondence: Dr A. Guterres, c/o Department of Anaesthesia, Flinders Medical Centre, Flinders Drive, Bedford Park, SA 5042 Australia.
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|Author:||Guterres, A.P.; Newman, M.J.|
|Publication:||Anaesthesia and Intensive Care|
|Article Type:||Case study|
|Date:||Mar 1, 2010|
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