Airway management during anesthesia for stereotactic placement of intratumoral drug delivery system in a patient with anaplastic astrocytoma.

Sir,

Functional neurosurgery with the assistance of stereotaxy and neuronavigation systems is being used increasingly. The procedure requires skilled airway management. However, data relating to airway management during stereotaxy are limited.

A 70-kg 21-year-old man, a known treated case of left frontal anaplastic astrocytoma on regular follow-up, presented with complaints of mild headache and seizures in the past 2 months and was on phenytoin daily. He was operated for tumor before following which, he received radiotherapy and chemotherapy. A magnetic resonance imaging (MRI) of the brain done 1 week before surgery revealed two small right frontal recurrent nodular lesions enhancing on contrast intratumoral catheter connected to a subcutaneous port access system was planned to be implanted using the stereotactic frame for enhanced delivery of the investigational medicine – AP 12009. The preanesthetic checkup was uneventful. Under local anesthesia, a titanium head-frame was fixed over his head for the MRI to stereotactically localize the area for the catheter placement. The patient was brought to the operation theatre for insertion of the intratumoral catheter after placing the stereotactic frame on top of the titanium head-frame.

After explaining the procedure to the patient, 0.2 mg glycopyrrolate and 4 mg ondansetron was given intravenously (IV). Mask ventilation could not be done because of the head-frame. Patient was given oxygen-enriched air by blowing oxygen on the face and anesthesia was induced with propofol. Following loss of eyelash reflex, a number 4 laryngeal mask airway (LMA) was inserted from the head end with an assistant lifting and pulling the jaw forward [Figure 1]. Ventilation was confirmed and vecuronium 8 mg and morphine 7 mg were given IV and anesthesia maintained with oxygen, nitrous oxide, and isoflurane 1 %. Burr hole was made on the left frontal region. The catheter was inserted stereotactically into the tumor and subcutaneously tunneled into the anterior chest wall. Once spontaneous respiratory efforts were adequate and arterial oxygen saturation was satisfactory, the LMA was removed. The procedure lasted 2 h and recovery was uneventful.

Figure 1

Titanium headframe in place along with the laryngeal mask airway in the patient for insertion of the intratumoral drug delivery catheter

Accurate intracranial placement of the ventricular catheter is needed for infusion of intratumoral chemotherapy. There is little literature about the anesthetic technique and difficulties faced during the procedure. Greenfield and Schwartz[1] reported a series of 20 patients undergoing the Ommaya reservoir insertion with the help of a frameless neuronavigation device. There is no mention about the anesthesia technique used in their article, as there was no hindrance to mask ventilation prior to intubation. More recently, trials have been conducted to test the efficacy of using the Ommaya reservoir to deliver gene therapy for cancer patients.[2] In a study of 172 patients undergoing functional neurosurgery, only monitored anesthesia care, with and without sedation, was used.[3] Bhade describes the airway management in patients coming for stereotactic biopsy; however, their stereotactic frame had an inbuilt intubation hoop in front, which makes airway access easy.[4] Preoxygenation with a mask may be difficult in these patients because of the stereotactic head-frame. We ventilated the patient with a mask but could not get a seal so immediately inserted the LMA once the patient was asleep. The other options for airway control were awake fiberoptic intubation or blind nasal intubation.

This case highlights the management of a patient for stereotactic catheter placement, wherein the airway is only partially accessible. LMA is a safe alternative in such cases as face mask ventilation is not possible and endotracheal intubation difficult.