Significance Of Narcotrend Assisted General Anesthesia Postoperative Extubation In Minimally Invasive Surgery Of Otolaryngology

Objective:Emergeance from general anesthesia can have higher risk involved, a mistimedextubation may increase the incidence of dyspnea, hypoxia, asphyxia, aspiration andother adverse events that could affect the effectiveness of the operation, physiologicalfunction and postoperative recovery, as well as prolonged hospital stays with addedcosts. Criteria and timing of extubation have been studied by anesthesiologist.Extubation of the trachea may be performed while the patient is deeply anesthetizedor is nearly fully awake. Patients are prone to cough and agitiation due to trauma, pain,discomfort and dimished anesthetic depth. During tracheal extubation after generalanesthesia patient hemodynamic changes may be secondary to suction andendotracheal stimulation. The adverse hemodynamic responses to awake extubationare well known. Myocardial oxygen consumption and coronary blood flow are altered,even cardio-cerebal vascular accident occur.However, deep extubation increses therisk of upper airway obstriction, respiration deprssion, reflux and aspiration ofgastric contents, which can be life-threatening. Propofol can reduce adverse reactionduring the extubation. An objective indicator is needed in monitoring the depth ofanesthsia. Optimal sedation depth during extubation can ensure safety and comfort of patients. The aim of this study is to investigate Endotracheal Extubation withNarcotrend assisted propofol-remifentanil anaesthesia, evaluate relationship withNarcotrend and propofol blood concentration, and using Narcotrend to detectprediction probability of conscious recovery and discuss feasibility and safety ofNarcotrend assisted general anesthesia extubation in otolaryngology surgery.Materials and Methods:There were23ASA I, II cases choosen with patients aging20-65years scheduledfor general anesthesia endotracheal intubation in minimally invasive surgery ofotolaryngology. During surgery, propofol was titrated through Target-ControlledInfusion (TCI) by using AstraZeneca Graseby3500. Intravenous injection ofremifentanil was done by TERUMO TE-332syringe and pumped by ManuallyControlled Infusion (MCI) to maintain anesthesia. The application of cisatracuriunprovided conditions for tracheal intubation and myorelaxation during the operation.The depth of anesthesia maintained at Narcotrend Index stage (NTS) was D2-E1.Intravenouly injection of sufentanil was stopped30min before the end of operationand cisstracuriun was stopped40min before the end of operation. Infusion ofremifentanil was stopped at the end of operation, while propofol TCI was maintained.Patients with TOF≥0.9were sent to postanesthsia care unit(PACU) and study was inresearch phase.The propofol plasma concentration was gradually adjusted post surgery. Patientsarrived PACU with the initial target plasma concerntration maintaining NTSD2-E1(T0), target plasma concerntration was2μg/ml for10min(T1), then1μg/mlfor10min(T2),10min after stopping infusion (T3),40min after stopping the infusion(T4),70min after stopping the infusion (T5),100min after stopping the infusion (T6).The Radial Artery propofol blood concentration (Cm), Narcotrend Index (NI),heart rate (HR), mean arterial pressure (MAP) and pulse oxygen saturation (SpO2), tidalvolume (Vt) and minute volume(Mv) was measured at different times.Patients opened their eyes after discontinuation of propofol when hearing theirnames called twice in a normal voice. Furmore, extubation was performed after patients was maintaining Vt>6ml/kg, respiration rate>12breaths/min, TOFr≥0.9,SpO2>95%. The time from termination of propofol to extubation was also recorded.The vital parameters for different time points after extubation were compared toNI on the prediction probability (PK) of consciousness. Narcotrend was used toevaluate patients before and after extubation recovery of consciousness.Results:1. NI, propofol blood concentration and changes in circulatory responses,oxygenation index NI increased gradually and propofol blood concentration graduallydecreased during recovery period of general anesthesia. The NI and patientemergeance period propofol blood concentration changes measured at different timesare statistically significant (P<0.05).MAP in T3increased compared with pre-anesthesiaand changes was statistically significant (P <0.05). Changes were not significantbetween pre-anesthesia and different times during recovery period. And there was nosignificant difference in HR, SpO2between pre-anesthesia and recovery period.2． The patient’s eyes opening NI value was85±4, after extubation the propofolblood concentration measured was1.3±0.5μg/ml.3. NI was negatively correlated with propofol Cm（r=-0.899，P=0.000）.Regressionequation was NI=-12.7Cm+99（F=672.6， P=0.000）.4. The NI and Cm prediction for eyes opening had a PK value of0.92and0.81,significantly higher than0.5(P <0.05), and was also higher than the MAP and HRcorresponding PK values (P <0.05).5． Dyspnea and hypoxemia did not occur during emergeance from generalanesthesia,and reintubation rate was0.Conclusions:1. Propofol can reduce changes in hemodynamics, as well as playing a protectiverole in the cardiovascular and cerebralvascular system by inhibiting the stressresponse during the extubation from general anaesthesia emergeance period.2. NI can accurately reflect the propofol blood concentration changes during theemergeance period. NI and Cm can predict changes in the consciousness of the recovery period from general anesthesia.3. Narcotrend monitoring shows NTS reach B1-B2classification for propofol underconventional dose of TCI after stopping infusion for10min or more, NI between81-89is safe for extubation. Narcotrend can safely assist General AnesthesiaExtubation in minimally invasive surgery of otolaryngology.