Conclusion
Our study is the first catheterization-supported study on the use of CS diameters and collapse in RAP estimation. IVC and CS parameters were evaluated with invasively measured RAP and significant results were obtained. That CS parameters are as significant as IVC parameters, shows that CS can now be used in RAP estimation. The high level of significance of correlation analyzes further strengthens this idea. Cut-off values for CS parameters have been determined in our study and will be an example for future studies.