Time to Post-Anesthesia Neurological Evaluation With Three Different Anesthetic Techniques

Time to Post-Anesthesia Neurological Evaluation and Hemodynamic Stability in Carotid Endarterectomy Comparing Three General Anesthetic Techniques Targeted to a Preset Bispectral Index Value: a Pilot Study

The objective of this pilot study is to analyze the differences in time to first postoperative neurological examination (cranial nerve XII - tongue movement, movement of extremities) and intraoperative hemodynamic stability with three different general anesthetic techniques that are used for carotid endarterectomy. Carotid endarterectomy surgery removes the plaque and stenosis but has a 1-3% risk of periprocedural stroke or death. The ability to detect neurological abnormalities early after surgery is vital in this patient population to facilitate timely additional diagnostics or interventions if a potential stroke is detected. Anesthetic techniques that facilitate an earlier reliable neurological exam will thus greatly benefit this surgical patient population. The primary objective of this pilot study is to determine the time difference from end of surgery to first neurologic exam between three commonly used anesthetic methods for carotid endareterectomy.

Carotid endarterectomy reduces the incidence of stroke in people with symptomatic, severe carotid artery stenosis. However, there are risks associated with this procedure such as stroke from carotid clamping with poor collateral brain circulation or embolization of carotid plaque debris (Sheth, 2017). Few surgeons monitor the brain during the procedure using SSEP or EEG, as most rely on intraoperative blood pressure management, shunting, and postoperative neurological exam (De Santis, 2016; Kobayashi, 2011). A Cochrane review of regional versus general anesthesia for carotid endarterectomy reveals no significant difference in outcomes (Vaniyaping, 2013). It is common practice at Cooper Hospital to deliver general anesthesia. The general anesthetic given may affect the length of time to first post-operative neurological response and the hemodynamic stability, though this is not well studied. A search in PubMed in April 2017 for "carotid endarterectomy AND (general anesthesia OR total intravenous anesthesia OR regional anesthesia) AND neurologic exam" ("endarterectomy, carotid"[MeSH Terms] OR ("endarterectomy"[All Fields] AND "carotid"[All Fields]) OR "carotid endarterectomy"[All Fields] OR ("carotid"[All Fields] AND "endarterectomy"[All Fields])) AND (("general anaesthesia"[All Fields] OR "anesthesia, general"[MeSH Terms] OR ("anesthesia"[All Fields] AND "general"[All Fields]) OR "general anesthesia"[All Fields] OR ("general"[All Fields] AND "anesthesia"[All Fields])) OR (total[All Fields] AND ("intravenous anaesthesia"[All Fields] OR "anesthesia, intravenous"[MeSH Terms] OR ("anesthesia"[All Fields] AND "intravenous"[All Fields]) OR "intravenous anesthesia"[All Fields] OR ("intravenous"[All Fields] AND "anesthesia"[All Fields]))) OR ("regional anaesthesia"[All Fields] OR "anesthesia, conduction"[MeSH Terms] OR ("anesthesia"[All Fields] AND "conduction"[All Fields]) OR "conduction anesthesia"[All Fields] OR ("regional"[All Fields] AND "anesthesia"[All Fields]) OR "regional anesthesia"[All Fields])) AND (neurologic[All Fields] AND exam[All Fields]) revealed no studies comparing anesthetic types and time to first post-operative neurological response in this surgical population. Through anecdotal experience at Cooper Hospital, patients are noted to emerge faster and follow commands sooner when not given preoperative midazolam and given a combined Total Intravenous Anesthetic (TIVA) and volatile inhalational anesthetic technique titrated to a bispectral index (BIS) of 50-60. Ruling out anesthetic causes of abnormal neurological function is vital in this patient population. Neurological dysfunction that is surgical in nature may require early intervention such as surgical reexploration or CT scan. "Time is brain", and a few minutes difference is enough to cause permanent neurological damage if a progressing stroke is not quickly identified. Anesthetic techniques that demonstrate a quicker return to baseline neurological function will greatly benefit this surgical patient population.

Study group A: no midazolam given; maintenance drugs started immediately after induction and airway is secured.

Study group B: no midazolam given; maintenance drugs started immediately after induction and airway is secured.

Study group C (control group): no midazolam given; maintenance drugs started immediately after induction and airway is secured.

Remifentanil - titratable; initial starting dose 0.05 mcg/kg/min Propofol - titratable; initial starting dose 75 mcg/kg/min Desflurane 0.5 MAC

Remifentanil - titratable; initial starting dose 0.05 mcg/kg/min Dexmedetomidine - titratable; initial starting dose 0.5 mcg/kg/hr Desflurane 0.5 MAC

Inclusion Criteria: 18 years of age and older Having carotid endarterectomy surgery Able to undergo a preoperative neurological exam Exclusion Criteria: Pregnant patients Prisoners Patients with dementia or reduced mental status acute or chronic Known brain tumor or head trauma Known severe, uncorrected coronary artery disease (CAD) Ejection fraction (EF) less than 15% Patients with intraaortic ballon pump (IABP) or other mechanical circulatory assist device Patients with severe chronic obstructive pulmonary disease (COPD) Combined surgical procedures (CABG and CAD) Patients with uncontrolled or severe anxiety requiring benzodiazepine administration Patients with history of difficult airway Sedation other than propofol, dexmedetomidine or volatile anesthetic agent (VAA) is needed for patient (i.e. ketamine in patients with history of neuropathic pain) Intubated or unconscious patients Patients on methadone or fentanyl patch Patients with known unusual or extreme anesthetic requirements Patients who would require an unusual amount of narcotic to control pain Patients having endarterectomy wherein surgeon requests local-regional anesthesia only Patients with known history of prolonged emergence from anesthesia Morbidly obese patients (BMI >40) Patients with scalp or forehead defects that prohibit application of BIS monitor strip