The use of regional anaesthesia in patients with a recognized difficult airway does not solve the problem of difficult airway; the difficult airway is still present. We report a case where giving regional anaesthesia in a patient with difficult airway, required emergency securing of the airway.
A 58-yr-old male patient (55 kg, 160 cm, ASA II) suffering from ankylosing spondylitis for 25 yr was scheduled for total hip replacement. Airway examination revealed interincisor distance of 4 cm, normal dentition, and reduced mentosternal distance of 6 cm due to fixed flexion deformity of neck. X-ray revealed ankylosis of spinous processes showing posterior joint involvement, resorption of the anterior surfaces of the vertebral bodies and ossification of the posterior ligaments and surrounding soft tissues. Anaesthesia was planned with a combined spinal epidural (CSE), separate needle technique, with difficult intubation cart ready. Premedication consisted of diazepam 10 mg orally the previous night and oral ranitidine 150 mg with metoclopramide 10 mg 2 h before surgery. On arrival in the operating room, routine monitoring was applied and an intravenous (i.v.) line was secured. The epidural block was attempted by the para-median approach through L3–4 space with the patient in the sitting position but the space could only be localized in the third attempt. While threading the epidural catheter, some initial resistance was met at the 10-cm mark but was overcome. Later, multiple attempts were made with 26-G Quinke's needle to locate the subarachnoid space, but free flow of cerebrospinal fluid could not be obtained and the procedure was abandoned. We decided to proceed with epidural block alone. Before fixing the epidural catheter, basal readings of heart rate (HR) and blood pressure (BP) were recorded and a test dose of lidocaine 2% 3 mL with epinephrine 15 μg (1:200 000) was injected, after negative aspiration, to confirm the position of catheter in the epidural space. Soon after the test dose the patient complained of dizziness and weakness. He was asked to lie down in the supine position and oxygen provided by face mask. Within a couple of minutes the patient became unconscious, apnoeic and BP dropped to 80/50 mmHg with severe bradycardia (heart rate < 36 min−1). Immediately atropine 0.6 mg and mephentermine 6 mg were given i.v. and attempts at mask ventilation with 100% oxygen were made. The patient's HR increased but it was not possible to mask-ventilate despite inserting an oral airway. An attempt to intubate the trachea with direct laryngoscopy also failed. By this time the patient had started desaturating with SPO2 reading 80%. However, we were able to place a size 4 laryngeal mask airway and positive pressure ventilation could be restored. Injections of mephentermine IV were repeated in increments of 3 mg to a total dose of 12 mg and simultaneously i.v. fluids were increased. The patient became haemodynamically stable (BP rose to 116/60 mmHg) over the next 10 min.
Once the patient was stabilized, the consultant anaesthesiologist decided to make one more intubation attempt using the McCoy's laryngoscope and a bougie. With the help of these, he was able to insert the bougie into the trachea and a Portex cuffed endotracheal tube of 7.5-mm size was placed into the trachea. The patient was not given any anaesthetic supplementation for endotracheal intubation. On examination, both the pupils were found to be dilated and fixed, and a diagnosis of total spinal anaesthesia was made. The surgeons were asked to proceed with the surgery and 66% N2O in O2 along with isoflurane 0.5–1% was added depending on the patient's haemodynamics. The surgery lasted for 3 h and vital signs were well maintained throughout the procedure. However, the patient did not require any muscle relaxant during the surgery and started having his own spontaneous respiratory effort by the end of surgery. Later N2O and isoflurane were turned off and the patient was extubated once adequate respiratory effort was established and he started responding to verbal commands. The epidural catheter was removed and the patient was kept in high dependency unit for the next 24 h.
There can be various reasons for this unusual spread of the local anaesthetic leading to a high spinal block. Firstly, the clinical presentation of the spread suggests that the drug might have been injected into the sub-dural space rather than the epidural space. This could have occurred as multiple attempts were tried before the loss of resistance was actually appreciated. Also a little force applied to thread the epidural catheter could have lead to the migration of the catheter itself into the sub-dural space. Secondly, attempts at spinal anaesthesia could have produced multiple punctures in the dura and the local anaesthetic agent could have seeped into the sub-dural or sub-arachnoid spaces. The addition of epinephrine to lidocaine would have prolonged the duration of action of the lidocaine. Recently, Steffek and colleagues reported total spinal anaesthesia following an epidural test dose in a patient with a normal airway, who recovered after 24 h without any late complications. However, surgery was postponed and the patient was operated 11 days later .
Y. K. Batra
1Department of Anaesthesiology and Intensive Care, Postgraduate Institute of Medical Education and Research, Chandigarh, India
1. Steffek M, Owcuk R, Szlyk-Augustyn M, Lasinska-Kowara M, Wujtewicz M. Total spinal anaesthesia as a complication of local anaesthetic test-dose administration through an epidural catheter. Acta Anaesthesiol Scand