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Anesthetic Management of a Patient in Prone Position with a Drill Bit Penetrating the Spinal Canal at C1-C2, Using a Laryngeal Mask

Valero, Ricard MD, PhD; Serrano, Silvia MD; Adalia, Ramón MD; Tercero, Javier MD; Blasi, Annabel MD; Sánchez-Etayo, Gerard MD; Martínez, Gloria MD; Caral, Lluis MD; Ibáñez, Guillermo MD

doi: 10.1213/01.ANE.0000111102.52964.7F
Case Reports: Case Report

Airway management in patients with penetrating neck trauma must guarantee cervical spine stability. Moreover, the prone position increases the risk of difficult ventilation and cervical spine injury. A 19-yr-old patient was brought to the emergency room in prone position with a drill bit protruding from the posterolateral aspect of his neck. The bit had entered the spinal canal below the first cervical vertebra, and placed near the odontoid peg. He was referred for surgical removal of the drill. The use of an inhaled induction of anesthesia, avoiding muscle relaxants, and ventilation through a laryngeal mask airway inserted in the prone position seemed to offer a satisfactory approach.

IMPLICATIONS: Management of patients with penetrating neck trauma must guarantee cervical spine stability. Moreover, the prone position increases the risk of difficult ventilation and cervical spine injury. Anesthesia may be induced and the airway can be managed with the patient already in the prone position for surgery.

Departments of *Anesthesiology and †Neurosurgery, Hospital Clínic de Barcelona, University of Barcelona, Barcelona, Spain

Accepted for publication November 18, 2003.

Address correspondence and reprint requests to Ricard Valero, MD, PhD, Anesthesiology Department, Hospital Clínic de Barcelona, University of Barcelona, Villarroel 170, 08036 Barcelona, Spain. Address e-mail to rvalero@medicina.ub.es.

Airway management in patients with penetrating neck trauma remains controversial and, whatever the technique used, it must guarantee the maximal stability of the cervical spine to avoid neurological impairment. Moreover, airway management in patients in the prone position augments the risk of difficult ventilation and tracheal intubation, and increases cervical spine injury hazard.

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Case Report

We report a case of a 19-yr-old male patient who experienced a penetrating neck trauma caused by an accident at work. He was brought to the emergency room in prone position with a 6-mm-diameter drill bit protruding from the right posterolateral aspect of his neck. There was local contusion and clear cerebrospinal fluid appeared to be leaking around the drill bit (Fig. 1). He was conscious, hemodynamically stable, breathing spontaneously, and voluntarily avoiding any movement. He had reduced sensation in the right lateral-posterior cervical and occipital zones. He had not eaten for 7 h before the accident. A lateral cervical radiography (Fig. 2) and a computed tomography scan (Fig. 3) showed that the drill had entered the spinal canal between the posterior elements of the first and the second cervical vertebrae, and placed near the odontoid peg and spinal cord. He was referred for surgical removal of the drill bit and exploration of the wound. He was sedated with 2 mg of midazolam and 50 μg of fentanyl. After manual in-line stabilization of his head and neck by six people, the patient was moved to the operating room table, while being kept in the prone position. Usual monitoring including Bispectral Index were placed. The proximal end (head support) of the operating room table was removed while maintaining manual in-line stabilization of the head and neck. Anesthesia was induced in the prone position with sevoflurane 8%, and 0.7 mg of atropine. Muscle relaxants were not administrated to avoid the loss of muscle tone, which we thought contributed to stabilizing the drill bit in the spinal canal. A size four laryngeal mask airway (LMA) was inserted in prone position (Fig. 4). This provided adequate ventilation and correct position was confirmed by passing a fiberoptic bronchoscope through it. Anesthesia was continued with sevoflurane (Bispectral Index values approximately 40) and fentanyl. An oxygen-air mixture (fraction of inspired oxygen 0.5) was administered using assisted ventilation at a pressure of 10 mm Hg with a 4-mm Hg positive end-expiratory pressure. When the drill bit was carefully removed, a tear of the inner coat of the right vertebral artery and a traumatic aneurysm, which finally broke, were observed. Bleeding was surgically controlled and a spinal dura tear was repaired. At the completion of surgery, the patient was turned to the supine position and emergence from anesthesia was uneventful. Once in the intensive care unit, the neurological examination showed a slight right upper extremity paresis that had resolved completely a few hours after surgery. Angio-magnetic resonance showed the presence of normal blood flow in the right vertebral artery. The patient was discharged home after 7 days.

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Discussion

Airway management of patients after a penetrating neck trauma is a major concern, particularly if there is involvement of the occipital-atlantoaxial complex (1,2). Airway management should avoid producing or worsening neurological deficits secondary to movements of the cervical spine, this risk being increased by the presence of a foreign body in the spinal canal. A wide range of different intubation techniques has been used in the management of these patients. Orotracheal intubation with manual cervical immobilization is considered an effective means of airway control in the multiple trauma patient at risk of or with spinal cord injury (3). Nasotracheal intubation causes decreased motion of the C5-C6 segment compared with oral intubation techniques (4). Airway maneuvers, such as chin lift and jaw thrust, can narrow the canal of an unstable C1-C2 segment, but no significant differences have been observed between these airway maneuvers, orotracheal and nasal intubation (5).

However, nasotracheal intubation is not without risk [slower procedure, nasopharyngeal bleeding, retropharyngeal perforation, etc. (3)]. Laryngeal mask devices are suitable for the unstable cervical spine because they do not require head and neck movements for insertion. The LMA exerts less pressure against the retropharyngeal mucosa and cervical vertebrae during insertion than the intubation laryngeal mask (ILM), although intubation through the LMA exerts more pressure than intubation through the ILM (6). However, the ILM produces segmentary motion of cervical vertebrae even with manual in-line stabilization in patients with cervical pathology (7). Awake fiberoptic intubation is probably the “gold standard.” However, patient collaboration is crucial, fiberoptic bronchoscopes are not always available at the emergency room, and the technique requires extensive training. In addition, fiberoptic intubation without muscle relaxants carries a potential risk of coughing which may occur during attempts to anesthetize the vocal cords, during insertion and manipulation of fiberoptic bronchoscope, or insertion of the orotracheal tube itself.

The prone position impairs orotracheal intubation by direct laryngoscopy. After induction of anesthesia in the prone position, the jaw and tongue fall anteriorly, making manual ventilation and LMA insertion easier (8). Finally, the prone position also makes it more difficult to administer adequate local anesthesia for fiberoptic intubation.

In case that ventilation through LMA was ineffective, “plan B” was to place an ILM for ventilation, and if ventilation still had not been effective, tracheal intubation through the ILM, guided under fiberscope view (and muscle relaxation), would have been the next step.

Trauma patients must be generally regarded as having full stomachs, even after long periods without ingestion. In this situation, tracheal intubation after a rapid sequence induction of anesthesia is the commonly chosen technique. Moreover, classical LMA is considered a device not able to protect the airway against aspiration. In the case of a full stomach, placing a classical LMA would be a potential high risk for aspiration. The use of the ProSeal™ LMA, or a completely different approach should then be considered. Fortunately, our patient did not eat for more than seven hours before the anesthesia took place, so the risk of aspiration was very small.

Manual immobilization does not completely prevent neck movement during patient transfer. Our main concern was the space relationship between the bit drill and the neck, even more than the neck movement itself. We managed to transfer the patient “en bloc.” In fact, it was a great aid that the patient, being aware of his situation, also helped to keep his neck and head still. Moreover, placing a Philadelphia collar was impossible because the drill was kept in place until surgery began. Furthermore, “halo” placement was not free of risk in this situation, and it would not have prevented the movement of the drill in relation to the neck.

Finally, sevoflurane was the selected anesthetic for induction. Propofol has already demonstrated its usefulness to promote good conditions for LMA insertion, and could have been a good choice for this reason (8). However, our aim was to try to keep spontaneous ventilation as long as possible during the anesthesia induction, so we chose sevoflurane instead of an IV anesthetic.

In this case, the use of an inhaled induction of anesthesia with sevoflurane, the avoidance of muscle relaxants, and the provision of effective ventilation through an LMA inserted in the prone position seemed to offer a satisfactory approach, which minimized anesthetic and cervical injury risks.

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References

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