evaluation of the effectiveness of L-citrulline plus nCPAP versus solitary nCPAP in improvement of endothelium dysfunction and decreasing the severity of obstructive sleep apnea in patients undergoing polysomnography in Baharloo hospital and are categoriazed as moderate to serevere OSA

evaluation of the efficacy of L-citrulline plus CPAP on improving endothelial function

Clinical trial with community-based and pragmatic control group, with parallel groups, double blind, randomization method: block randomization with stratification

If FMD>NMD, we can conclude that there is endothelial dysfunction and for ruling out arterial muscular dysfunction we use TNG and assess the artety by color doppler sonography. Then we randomly divide patients into 2 groups. For group no.1, we begin the cpap therapy for 1 month plus placebo and for group no.2 ,we use CPAP during the night and L-citruline(Stimul Biocodex, which contains 1 gram of citrulline malate) as following: For the first 10 days, 3 times daily, and for the following 20 days,2 times daily. After 1 month, we evaluate patients again for AHI and the ratio of FMD to NMD. As the AHI level can be extracted using CPAP memory, we calculate NMD and FMD levels by Brachial artery color doppler ultrasonography.

Inclusion criteria: 1. patients who are categorized as moderate to severe OSA (obstructive sleep apnea) on basis of AHI critera and polysomnography 2. proving their endothelial dysfunction (FMD>NMD) by colordoppler sonography 3.ruling out arterial muscular dysfunction by colordoppler sonography Exclusion criteria: 1- if less than 40 days is passed from patine's treatment for OSA 2.History of CAD 3-Hear failure or MI 4-Smoking

We randomize patients into 2 groups. Both groups receive CPAP for 4 hours every night during 1 month. For the intervention group we apply L-citruline (Stimol-biocodex) with following prescription: for the first 10 days,3 times daily and for the 20 following days,2 times a day. for the control group we prescribe placebo with the same protocol.

Brachial artery diametre change

We divide patients into two groups by permuted block randomization. Since diabetes status of patients can be as an important covariate which affects the outcome, we control it by stratification approach. By using https://www.sealedenvelope.com we are going to make 2 randomized group in the basis of their diabet status and only one person is going to be aware of our allocation concealment . The investigator get in touch with that person each time that we have a new participant and ask which of the groups should the participant get involved with and for each drug box we have a number on it which is assigned randomely.

Usage of placebo for the patient and assign each patient with a code for radiologist blindness and allocating numbers to each box of drugs