Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 7 4 2021 10 18 223 226 Alireza Zeraatchi Department of Emergency Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. Taraneh Naghibi Department of Anesthesiology and Critical Care Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. Hamid Kafili Department of Anesthesiology and Critical Care Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. Somayyeh Abdollahi Sabet Department of Community Medicine, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. 2021 06 02 2021 06 19 Background: Hemodynamic monitoring its early stabilization is very important in critically ill patients. Evaluating the Internal jugular vein diameter during respiratory cycles by the means of Point-of care ultrasound provides an important, easily available and precise index for monitoring hemodynamic status; a new method which is called Internal Jugular Vein Collapsibility Index (IJV-CI). Any events that alters intrathoracic volumes and pressures may affect this index. In this study we investigate the effects of various levels of positive end-expiratory pressure on this index. Methods: Thirty mechanically ventilated patients were studied. We used three different PEEP levels (0, 5 and 10 cmH2o) and point-of-care ultrasound evaluation of IJV (Internal Jugular Vein) diameter to determine the IJV-CI. The analysis were performed using SPSS V.25.0. Results: Patients were included men (76.6%) and women (33.3%). The mean age of patients was 39.65±3.4 for men and 42.71± 9.34 for women. The IJV-CI were 20.71±11.77 and 24.25±11.46 in PEEP=0 and PEEP=10 cmH20 groups respectively. In 5cmH20-PEEP group median and interquartile range were 16.45(14.8). The IJV-CI in three different PEEP levels were not statistically significantly different. Conclusion: According to the finding of this study, we found no evidence of an optimal PEEP level to measure The IJV-CI. https://aacc.tums.ac.ir/index.php/aacc/article/view/366