The results of several recent studies on endoscopic sinus surgery through topical administration of tranexamic acid are encouraging in terms of the efficacy of tranexamic acid for intraoperative bleeding and other pathological conditions.The purpose of this study is to analyze the efficacy of nebulized tranexamic acid to improve the surgeon and patient experiences of sinus surgery and know the effective and safe dose of nebulized tranexamic acid.

A written informed consent will be taken from the patients.The study involved adults of either sexes (age 18-65 years) of ASA I-II who will be listed for elective functional endoscopic sinus surgery (FESS) under general anesthesia, with normal accepted coagulation profile and hematocrit value ≥30 %. Excluded from the study patients with chronic renal failure, liver cirrhosis, bleeding disorders, current anticoagulant therapy, pregnancy or breastfeeding, impaired color vision, severe vascular ischemia, history of venous thrombosis, pulmonary embolism, long term treatment with acetylsalicylic acid or non-steroidal anti-inflammatory drugs not discontinued before surgery, a hemoglobin (HB) concentration <10 mg/dl or allergy to TXA.

Randomization: A random number sequence created by an internet website (http://www. random.org) will be used for patients' allocation. The random number sequence was retained in closed opaque envelopes released the day of the surgery by an independent physician not involved in the study. Patients will be assigned randomly to three groups (30 subjects each); saline placebo (Group S) and two different doses of preemptive nebulized tranexamic acid (Group T1) and (Group T2).To keep blinding, Group S will receive 2 sessions of nebulization each by 5 ml saline. Group T1 will receive one nebulization session 500 mg tranexamic acid (5 ml) and another one by 5 ml saline. Group T2 will receive 2 nebulization sessions each by 500 mg tranexamic acid (each by 5 ml)

Inclusion Criteria:

• Either sexes (age 18-65 years) of ASA I-II who are listed for elective functional endoscopic sinus surgery (FESS) under general anesthesia
• normal accepted coagulation profile and hematocrit value ≥30

Exclusion Criteria:

• chronic renal failure
• liver cirrhosis
• bleeding disorders
• current anticoagulant therapy
• pregnancy or breastfeeding
• impaired color vision
• severe vascular ischemia
• history of venous thrombosis, pulmonary embolism
• long term treatment with acetylsalicylic acid or non-steroidal anti-inflammatory drugs not discontinued before surgery
• hemoglobin (HB) concentration <10 mg/dl _allergy to TXA.