***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: In local anesthesia , various epinephrine concentrations are applied for its vasoconstrictive effect . This study was conducted to observe the effect of epinephrine on intraoperative bleeding and also to evaluate hemodynamic changes during skin surgery . Ninety-six patients scheduled for skin surgery under local anesthesia were divided into three groups administered three different concentrations of epinephrine ( 1:50,000 , 1:100,000 and 1:200,000 ) with 1 % lidocaine ( an average of 5.7 mL ) . The rate of bleeding and hemodynamic changes were assessed during surgical procedure . The surgeon 's rating of intraoperative bleeding was significantly lower in the group administered epinephrine concentration of 1:50,000 as compared with the group on epinephrine concentration of 1:200,000 . However , there was no significant difference between the groups administered epinephrine concentrations of 1:200,000 and 1:100,000 . Except for diastolic blood pressure at 1 min after injection of local anesthetics , transient changes of hemodynamic parameters were observed , with no statistically significant difference among the three anesthetic solutions used . It is concluded that , for local anesthesia , the rate of intraoperative bleeding is influenced by epinephrine concentration , and that 1:50,000 epinephrine provides optimal clinical efficacy for the local bleeding control during dermatologic surgery How should health care professionals choose among the many therapies cl aim ed to be efficacious for treating specific disorders ? The practice of evidence -based medicine provides an answer . Advocates of this approach urge health care professionals to base treatment choices on the best evidence from systematic research on both the efficacy and adverse effects of various therapeutic alternatives . Ideally , health care professionals would compare different treatments by referring to r and omized , double-blind , head-to-head trials that compared the treatment options . Although individual medications are typically well research ed when these placebo-controlled studies are performed , studies that directly compare treatments are rare . In the absence of direct head-to-head trials , other evidence comes from indirect comparisons of two or more therapies by examining individual studies involving each treatment . This article provides an introductory review of methods of such indirect comparisons of therapies across studies , provides examples of how these methods can be used to make treatment decisions , and presents a general overview of relevant issues and statistics for readers interested in underst and ing these methods more thoroughly Background The aim of this study was to determine the effect of pterygopalatine fossa infiltration with lidocaine and adrenalin on bleeding in the surgical field during endoscopic sinus surgery . Methods A prospect i ve blind r and omized controlled trial was performed . Fifty-five patients were r and omized to receive a unilateral transoral infiltration of the pterygopalatine fossa with 2 mL of 2 % lidocaine and 1:80,000 adrenalin . The operating surgeon was blinded as to which side had been infiltrated at the start of surgery . The surgical field was grade d on a previously vali date d surgical field grading scale every 15 minutes with the side being operated on alternated every 30 minutes . The pulse , mean arterial blood pressure , and end-tidal CO2 concentration were monitored with each surgical field observation . Results At each individual time point from 30 minutes to 3.5 hours there was a significant difference in surgical grade between injected and noninjected sides in favor of the injected side ( p = 0.01 ) . The difference between surgical grade s averaged across all time points was slight but significant . The injected side had an overall mean of 2.59 ( SE , 0.22 ) compared with 2.99 ( SE , 0.23 ) for the noninjected side . Heart rate also was found to correlate independently to surgical grade . Conclusion Injection of the pterygopalatine fossa result ed in an improved surgical field during endoscopic sinus surgery Nasal polyps are associated with the inflammation of the nasal cavity and the sinus mucosa . When medical treatment can not solve a patient ’s problem , a functional endoscopic sinus surgery may be indicated . Bleeding impairs the surgery field during operation and increases the operation risk and time . Pre-operative corticosteroids can reduce bleeding during surgery . In this study , we have evaluated the effect of pre-operative single-dose prednisolone ( 1 mg/Kg/dose 24 h before surgery ) versus 5-day prednisolone ( 1 mg/Kg/day before operation ) on the bleeding volume and the surgery field quality during FESS . In this mono blind r and omized clinical trial , 80 patients with bilateral nasal polyps were r and omly assigned in two groups . The first group ( A ) received a single dose of 1 mg/Kg/dose prednisolone on the day before the surgery . The second group ( B ) received 1 mg/Kg/day prednisolone for 5 days before the operation . The patients were operated on under general anesthesia through the same protocol . The mean arterial blood pressure was 70–80 mm Hg in both groups . The surgeons were not aware of the patients ’ group . The bleeding volume and the surgeons ’ opinion about the surgery field quality were recorded at the end of the procedure and analyzed by Chi-square and t test . The two groups were not significantly different in their overall demographic and clinical characteristics . The mean bleeding volume during the operation was 266.5 ± 96.31 ml in group A and 206 ± 52.81 ml in group B ; there was a significant difference between the groups ( P value = 0.038 ) . There was no significant difference between the groups in the surgeons ’ opinion about the surgery field quality ( P value = 0.09 ) . In conclusion , unlike a single dose ( 1 mg/kg/dose ) , treatment with 5-day prednisolone ( 1 mg/kg/day ) can reduce blood loss during FESS more efficiently and may improve the surgery field quality slightly . But this difference is not clinical ly significant OBJECTIVE /HYPOTHESIS To find out the factors related to the volume of intraoperative blood loss during  endoscopic sinus surgery  and to vali date the role of reverse Trendelenburg position ( RTP ) in controlling blood loss . STUDY DESIGN Prospect i ve , controlled , single-blind study . METHODS  Endoscopic sinus surgeries for chronic rhinosinusitis with or without polyposis were performed in 60 patients , which were r and omly categorized into two groups . The study group ( RTP group ) consisted of 30 patients laid on operation table with the RTP of 10 degrees during the whole surgery , and the control group with 30 patients completely laid supine . All operations were performed by the same operator ( the first author ) without using hemostatic agents during the operation . Intraoperative blood loss was estimated by total volume of blood loss , blood loss per minute , and surgical field scale . Multiple factors related to blood loss , such as computed tomography scores , operation time , mean arterial pressure , polyposis , fungal sinusitis , and anesthetic agents were compared . RESULTS There existed significant differences in total blood loss , blood loss per minute , and surgical field between the RTP group and supine group . In multiple analyses within the two groups , presence of polyp , non-fungal sinusitis and use of microdebrider exhibited a significant higher blood loss rate in the RTP group . CONCLUSION RTP may reduce intraoperative blood loss . Besides , fungal sinusitis and rhinosinusitis without polyposis may contribute to a lesser intraoperative blood loss OBJECTIVE : To find out whether the constant preoperative use of a topical corticoid ( mometasone furoate [ MF ] ) could really improve the operative field quality and decrease bleeding during endoscopic sinus surgery ( ESS ) . STUDY DESIGN : Double-blind , r and omized controlled trial . SETTING : Tertiary referral center . SUBJECTS AND METHODS : Seventy patients with chronic rhinosinusitis ( CRS ) with and without polyps underwent ESS under st and ardized general anesthesia with equal r and omization into two groups . During four weeks within the preoperative period , 35 cases were treated with MF , while the other half received placebo matching sprays .  Total blood loss , operation time , and surgical field quality were recorded . RESULTS : Intraoperative blood loss in the MF-treated group was 142.8 mL , less than in the control group ( 170.6 mL ) . The difference between the groups is 27.7 mL ( 95 % confidence interval [ CI ] 3.5–51.92 ) , statistically significant : P = 0.025 . Time of surgery was 59 minutes in the MF group and 70 minutes in the control group . The difference was 11.2 minutes ( 95 % CI 2.82–19.51 ) , which is statistically significant : P = 0.009 . The quality of the endoscopic surgical field was significantly better for patients treated with MF . Treatment with topical corticoid enables significantly reduced bleeding , decreased operation time , and improved endoscopic vision during ESS for CRS . CONCLUSION : The use of topical corticoid ( MF ) in the preoperative period can improve endoscopic vision , reduce bleeding , and decrease operation time in CRS patients with and without polyps undergoing ESS , but our sample size can not exclude small , and possibly trivial , group differences Background This study was design ed to compare differences in intraoperative blood loss , mean arterial blood pressure ( MABP ) , and duration of surgery when 0.25 % bupivacaine with 1:200000 epinephrine is injected , preoperatively , versus normal saline ( NS ) , during functional endoscopic sinus surgery ( FESS ) . Methods A prospect i ve , double-blind r and omized placebo-controlled study was performed . Part I involved 46 patients who were infiltrated with 0.25 % bupivacaine with 1:200000 epinephrine on one side of the nose and sterile NS on the other ( control ) . Part II involved 30 patients infiltrated with 0.25 % bupivacaine with 1:200000 epinephrine bilaterally and 30 patients with NS bilaterally ( control ) . Patient demographics , preoperative MABP , intraoperative MABP , duration of surgery , and total estimated blood loss ( EBL ) were recorded for each side ( part I ) and case ( part II ) . Results For part I , there were 46 patients ( mean age , 49 years ) , 24 women and 22 men .  MABP was 72 mmHg for each side ( p = 0.97 ) . Preoperative MABP was 93 mmHg . Duration of surgery was 48 minutes for epinephrine side and 45 minutes for control ( p = 0.17 ) . Total EBL was 185 mL for the epinephrine side and 197 mL for control ( p = 0.53 ) . For part II , there were 60 patients ( mean age , 56 years ) , 28 women and 32 men . The MABP was 77 mmHg for the epinephrine group and 72 mmHg for control ( p = 0.048 ) . Preoperative MABP was 100 mmHg for the epinephrine group and 97 mmHg for control ( p = 0.37 ) . Duration of surgery was 2.25 hours for the epinephrine group and 2.08 hours for control ( p = 0.17 ) . Total EBL was 589 mL for the epinephrine group and 538 mL for control ( p = 0.64 ) . Conclusion There was no significant reduction in intraoperative blood loss during FESS when local anesthetic containing epinephrine was used compared with infiltration with NS . More importantly , part II shows a significantly higher MABP associated with infiltration of epinephrine . Parts I and II did not show a significant difference in preoperative MABP or duration of surgery Functional endoscopic sinus surgery ( FESS ) is one of most common surgeries in otorhinolaryngology practice . It is done in the narrow confines of the nasal cavity . Bleeding into the surgical field is a major problem faced by endoscopic surgeons . To assess the effectiveness of pterygopalatine fossa infiltration with lignocaine and adrenaline in controlling surgical field bleeding during endoscopic sinus surgery . A r and omized blinded study was done among 68 patients who underwent FESS . Infiltration with 2 % lignocaine with 1:80,000 adrenaline was given only on one side and the surgeon was blinded as to which side was infiltrated and he was asked to assess the surgical field using a st and ard scale . There was statistical significant improvement in surgical field on the infiltrated side ( p = 0.001 ) with almost 25–30 % improvement in surgical field on the infiltrated side . The surgical field bleeding also varied with the blood pressure with a positive correlation . There were no complications associated with the procedure . Pterygopalatine fossa infiltration with lignocaine and adrenaline is an effective technique in reducing surgical field bleeding during FESS . It can be combined with nasal decongestion or hypotensive anaesthesia for an optimum surgical field OBJECTIVE In the literature , there has been controversy regarding the length of the greater palatine canal . If the pterygopalatine fossa is infiltrated in an attempt to reduce bleeding during sinus surgery , this information is important to be able to place local anesthetic with maximal effect and the least 
    Output:
    
Results The endoscopic grade in the treatment group was significantly reduced when compared with the control group .
Conclusion This study demonstrated that GPC injections of local anesthesia with 1:80,000 adrenaline for ESS effectively reduced intraoperative bleeding .
Additionally , this procedure showed no significant adverse effects , such as hemodynamic instability .