Clinical Study Of Methylene Blue Tracing Technique In Preventing Salivary Fistula After Parotidectomy

Backgrounds and ObjectivesParotid tumors are the most common tumors in the oral and maxillofacial region,accounting for 3%of all head and neck tumors.Surgery is the main treatment.Surgical techniques have evolved from simple enucleation to lobectomy,and then partial parotidectomy over the years,with the deeper understanding of the pathology of parotid gland tumors.Partial parotidectomy which preserves of partial parotid gland tissue is the result of the development of functional surgical.But this method indicated a high incidence rate of parotid fistula.A salivary fistula is generally considered to be the destruction of parotid tissue integrity,especially parotid duct system.Saliva secreted from remaining gland tissues could leak into the operation area from the non-closure of the main ducts,and fluid retention will form a salivary fistula to a certain extent.In order to prevent salivary fistula,it is necessary to identify and ligate the branch duct of parotid gland carefully.After the tumor is excised,the parotid stump needs to be tightly stitched.And pressure dressing to the parotid region and negative pressure drainage are involved after surgery.However,the branch ducts are too small,numerous,and no obvious color,which is difficult to be identified completely during surgery.When the parotid stump was sutured,some of the branch ducts are inevitably missed because of the facial nerve protection,resulting in salivary fistula.The key to reducing the rate of salivary fistula is how to identify and ligate the ruptured branch ducts effectively.The lack of effective methods to identify the ruptured branch of the parotid duct is a key pain point for clinical prevention of salivary fistula.Methylene blue is a common stain in clinical practice,which was first used in parotid surgery in the 1950s.The methylene blue was injected through the opening of parotid gland duct pre-surgery to blue the parotid glands,but the tumor and facial nerve were not stained,so it was easy to differenciate the tumor and facial nerve.However,this technique blued the entire surgery area,which is not convenient to discover parotid duct fistula.It is innovative that methylene blue was used to identify parotid ductal fistula.This technique is simple to operate,low in cost and a supplement to parotid stump suture.The purpose of this study is to study the effectiveness and safety of methylene blue used in preventing salivary fistula.Materials and Methods1.Clinical analysis of methylene blue tracing technique in parotidectomy:Retrospective analysis was performed on 101 cases of unilateral parotid superficial lobe benign tumor resection saving the main parotid duct in the Oral and Maxillofacial Surgery of the Eastern District of Shandong Provincial Hospital Affiliated to Shandong University from January 1,2017 to December 31,2017.The data including age,gender,surgical method,tumor location,size,pathology,postoperative salivary fistula,temporary facial paralysis and other complications were collected.2.A randomized controlled trial of methylene blue tracing technique in preventing salivary fistula after parotidectomy:Patients diagnosed as unilateral benign tumors in the superficial parotid gland and planned to undergo surgery were randomly divided into the methylene blue group and the traditional group.Both groups underwent parotid superficial parotid lobectomy with general anesthesia with tracheal intubation.In the methylene blue group,diluted methylene blue was injected into the opening of parotid duct after tumor resection.Identifying and ligating the fistula of the parotid duct according to the outflow of methylene blue in the surgery area,then stitched the parotid stump.In the traditional group,the parotid gland stump was sutured directly after the tumor resection.Both groups of patients underwent tissue patch implantation and negative pressure drainage.Removing the negative pressure drainage was conducted when the drainage volume is less than 20mL within 24h,and pressure dressing.The stitches were removed one week post-operation,and pressure dressing was performed again for one week.The follow-up time was one week,two weeks,and three weeks after operation,and salivary fistula,facial paralysis and other complications were checked at each follow-up.Results1.Clinical analysis of methylene blue tracing technique in parotidectomy:38 cases of parotid ductal fistula were ligated according to methylene blue stained(methylene blue group),and 63 cases of parotid duct fistula ligation using traditional techniques(traditional group).The postoperative salivary fistula rate in the methylene blue group was 7.89%,which was lower than the traditional group(20.63%,P=0.156).The postoperative facial paralysis rate in the methylene blue group was 10.53%,which was higher than the traditional group(9.52%,P=1.000).The median operation time in the methylene blue group was 135 minutes,and the interquartile range was 33,which was significantly higher than the traditional group(the median is 105 minutes,the interquartile range is 50,P<0.001.There was no statistical difference in age,gender,surgical procedure,pathology,affected side,tumor size,and location between patients with salivary fistula or facial paralysis or not(P>0.05).2.A randomized controlled trial of methylene blue tracing technique in preventing salivary fistula after parotidectomy:From 2018.4 to 2020.6,245 patients were included,including 122 in the methylene blue group and 123 in the traditional group.The salivary fistula rate in the methylene blue group was 4.92%,which was significantly lower than the traditional group(12.20%,P=0.042).The rate of temporary facial paralysis in the methylene blue group was 13.93%,which was higher than the traditional group(11.38%,P=0.548).The median operation time of the methylene blue group was 113 minutes and the interquartile range was 44,which was significantly higher than that of the traditional group(median 100 minutes,interquartile range 40,P=0.002).The median age of patients with salivary fistula was 48 years and the interquartile range was 26,which was significantly lower than that of patients without salivary fistula(median 53,interquartile range,P=0.037).The median tumor size of patients with temporary facial paralysis after surgery was 3.0 cm,and the interquartile range was 2.0,which was significantly larger than that of patients without temporary facial paralysis(median 2.5,interquartile range 1.3,P=0.015).Conclusions1.Methylene blue tracing technique can accurately identify and ligate parotid duct fistula during operation,which can significantly reduce the incidence of salivary fistula after parotidectomy,and it is valuable in parotid surgery.2.Methylene blue prolongs the operation time,but does not significantly increase the incidence of temporary facial paralysis.3.Age is a related risk factor for salivary fistula after parotid surgery,and young patients are more likely to develop salivary fistula.4.Tumor size is a related risk factor for temporary facial paralysis after parotid gland surgery.The larger the tumor,the more likely to develop postoperative facial paralysis.