Ensure connections are tight. Reduces transmission of infection. Prevents needle from lacerating vessel during insertion. Allows for cooperative effort. Allows signal to be transmitted to monitor.
Intact system gives better readings and reduces risk of infection.
Level air-fluid interface to right atrium. If lower than heart, yields false high pressures. If higher than heart, will yield false low pressures. Eliminates atmospheric influence on pressure readings. Perform a square wave test.