What test to use and how to calculate needed sample size?

in this experiment subjects are patients in a hospital. I have two factors:
-Factor A (2 levels)
-Factor B (2 levels)
I am also doing repeated measures so for each combination of A*B, I will do 3 measures in total.
This means that for each patient I will have 12 rows in a table.

I am measuring two values (they are related to blood pressure and lung capacity), so I will have 24 responses in total for each patient, 12 values for Response 1, and 12 values for Response 2.

You can check an example of the data for a single patient in the attachment.

The goal of the test would be to check if variables Response 1 and Response 2 are correlated.

The questions I have are:

1. What test to use in this situation?
2. How to calculate the needed sample size, ie. how many patients would I need to make a strong conclusion about correlation of these two variables?