French size of a sheath refers to the inner diameter. The outer diameter Fr size is approximately the sheath size +1.
Rules of thumb:
- Manual pressure to be held for 3 minutes per Fr size. Eg. 18 minutes manual pressure held for a 6 Fr Sheath.
- Length of time of bedrest with accessed artery leg straight = N-1 rule. Eg. 4 Fr sheath --> leg straight for 3 hours.