A Research On The Effect Of Vagus Nerve Block In Cervical Part To Prevent Oculo-vagal Reflex

Objective:To investigate the effects of vagus nerve block in cervical part on ocular pneumogastric nerve reflex and untoward reaction induced by reflex. Scilicet, vagus nerve dominating myocardium is blocked, trisplanchnic nerve gains advantages. Heart rate speeds up. So vagus nerve block can reduce the incidence of OVR and prevent OVR. It also can avoid the side effects of applying anticholine drugs traditionally.Methods:40patients who accepting prosthesis of orbital wall bone fracture (ASA:Ⅰ-Ⅱ, age:19-45years) randomly separate into two groups:experiment group and control group. Experiment group adopts vagus nerve block in cervical part before anesthesia. Patient need prostration without pillow, shoulder bolstered, contralateral head turning, and hands placed at body sides naturally. Mastoidale linking with the sixth transverse process of cervical vertebra, thyrohyoid bone perpendicular to that line, the intersection is the location puncturing. Sterilize with routine method, pinhead points to subtus of common carotid artery. When the pinhead arrives at subtus of common carotid artery, we pump back the syringe. If there isn’t blood, liquid and gas in the syringe, we inject the drug. The size of the pinhead is five. Adults accept Lidocaine8～10ml. Get venous blood before and after puncture5-10min, and detect the change of ACh. Indexes record the changes of MAP, HR and SpO2before block (To), vagus nerve block in cervical part3min (T1),5min (T2),10min (T3) and120min (T4). We record the changes of MAP and HR when we oppress the eyeball or drag muscular apparatus, and times of using atropine. Adverse reactions and the alteration of ACh in venous blood before and after block are recorded. Two groups accept the same anesthesia induction:midazolam0.1mg/kg, fentanyl0.03～0.05mg/kg, rocuronium0.6mg/kg, and propofol1mg/kg. Patients need mechanical control respiration after tracheal intubation, frequency of respiration is12times per min, tidal volume is lOml/kg, ratio about inhalans and expirium is1:2. Maintenance of anesthesia require1%isoflurane volatilizing and4ml/(kg-h) propofol, remifentanil0.05μg/(kg-min) pumping. Carbon dioxide partial pressure at expirium maintain at35～45mmHg. We boost fentanyl in order to keep the depth of anesthesia.Results:(1)Age, body weight, body height, average of base blood pressure, base heart rate, the time of keeping anesthesia and the time of undergoing surgery between the two groups don’t have statistically significant (p>0.05);(2)In experiment group, we find that heart rate significantly increase after block3min-120min compare with before block (p<0.05), but blood pressure and SpO2don’t have statistically significant (p>0.05);(3)The incidence of OVR is lower, time of suspension in surgery and the times are higher in experiment group than in control group, but they haven’t statistically significant (p>0.05);(4)The incidence of adverse effects in PACU such as: nausea and vomiting have statistically significant(p<0.05); bradycardia, shakes, pain, region hematoma and hoarse voice in two groups don’t have statistically significant (p>0.05);(5)Content of ACh in experiment group changes significantly, it is lower after block than before block(p<0.05).Conclusion:Vagus nerve block restrains the efferent nerve which dominating myocardium, trisplanchnic nerve gains advantages. Then heart rate speeds up. So it reduces the incidence of OVR and prevents OVR. Vagus nerve block in cervical part is simple, safe, act effectively and no complications. So it is worth to generalize and put into practice clinically.