We report a case of a super morbid obese 48-year-old male with a body mass index of 54, who presents for an AC for a 6cm lesion involving the left anterior temporal lobe, basal ganglia, inferior frontal lobe and the thalamus. Location of the cranial lesion incorporated sensorimotor and language areas. Therefore, during the resection phase of the surgery, along with neuromonitoring, patient would have to perform language and vocabulary tasks to optimize tumor resection and minimize neurological complications.
Patient’s past medical history was significant for hemorrhagic stroke, hypertension, COPD on home inhalers, OSA, insulin dependent diabetes, and GERD. Due to the cranial lesion, patient was also experiencing seizures despite being on antiepileptics. Airway exam revealed Mallampati of 3, thick neck, and at least three fingerbreadth thyromental distance. Patient also had a documented allergy to clonidine and mentioned developing a rash while on clonidine.
Given the goals of the surgery and patient comorbidities, we planned for monitored anesthesia care with intravenous (IV) dexmedetomidine, remifentanil, and propofol. We researched the use of dexmedetomidine with clonidine allergy in PubMed and was unable to find any published literature regarding its use in a patient allergic to clonidine. We reached out to our institution’s inpatient clinical pharmacist for guidance. Our clinical pharmacist confirmed the lack of published literature but did mention, based on experience, dexmedetomidine had been safely used in two prior patients who were also allergic to clonidine. With this information we discussed the use of dexmedetomidine with the patient and the potential risk of allergic reaction. Patient understood the risk and consented to the anesthetic plan.
Prior to taking the patient to the operating room, the patient had two peripheral IV access, was given a breathing treatment, 20mg of IV famotidine, 10mg of IV metoclopramide, and 4mg of IV ondansetron. Bilateral nares were prepped with neosynephrine in case nasopharyngeal airway would have to be used during the procedure for airway maintenance. Upon arrival to the operating room IV infusion of 0.4mcg/kg/hr of dexmedetomidine and 0.03mcg/kg/min of remifentanil was immediately started after standard monitors (ECG, pulse oximetry, and noninvasive blood pressure cuff) and salter nasal cannula were placed. Given patient’s history of diabetes and the need to check blood glucose throughout the case, hemorrhagic stroke, and hemodynamic effects of the IV anesthetic, radial arterial catheter was inserted in the operating room with 1% lidocaine local anesthetic. Video laryngoscopy, intubation equipment along with supraglottic airway, and emergency medications (epinephrine, diphenhydramine, levetiracetam, and lorazepam) were ready in the operating room.
During the 12-point scalp block and placement of urinary foley catheter increments of 5-10mg of propofol were given for patient comfort while maintaining a Richmond Agitation Sedation Score (RASS) of -1 to -2. Throughout the procedure, goal was to keep patient arousable so patient could communicate potential allergic symptoms. Prior to pinning of the head in the Mayfield, in addition to the increments of 5-10mg of propofol, propofol infusion was also started at a rate of 5ug/kg/min and titrated upward as tolerated to maintain target RASS. Patient tolerated the scalp block, positioning, and pinning well.
During the opening phase of the dura, patient tolerated upward of 0.7mcg/kg/hr of dexmedetomidine, 0.03 mcg/kg/min of remifentanil, and 12mcg/kg/min of propofol. Any increase in the propofol dosing led to airway obstruction. All IV infusions were paused once the dura was opened for the awake phase of the AC. Patient successfully underwent testing of language, memory, and motor during mapping and resection. Once resection was completed, dexmedetomidine and remifentanil infusions were reinitiated at 0.4mcg/kg/hr and 0.3mcg/kg/min, respectively, for the post-awake phase.
Throughout the procedure, patient’s oxygenation was maintained with a salter nasal cannula without the need of oral or nasopharyngeal airway. Patient remained hemodynamically stable throughout the case without the need of any vasopressors. Toward the end of the post-awake phase, patient became hypertensive, which was resolved with IV labetalol. After the surgery concluded, patient was transferred to the post-anesthesia care unit for recovery and transferred to the intensive care unit for monitoring. Patient was discharged on post-operative day 6.