Mattress retainers or stops are designed to hold a mattress in a particular position in the mattress support platform. If a tester can easily override the mattress stop by pushing the mattress, then it is possible that this movement could occur during normal use by a patient. Thus the bed system should be tested with the mattress pushed as far away from the rail being measured as possible (e.g., against the opposite rail). However, the tester should not force the mattress past the stops. Similarly, if moveable stops are used, then the stops should be positioned so that they do not inhibit mattress position during testing, because the moveable stops could possibly be out of position at some time. The rationale for this thinking is that if the mattress can be in an adverse position, the testing should reveal this possibility. Thus, if mattress stops can mitigate the adverse mattress position, they should be deployed to do so.
This question is also addressed in “Testing Tips and Frequent Questions” in Appendix F-HBSW Dimensional Test Methods for Bed Systems of FDA’s Hospital Bed System Dimensional and Assessment Guidance to Reduce Entrapment – Guidance for Industry and FDA Staff. It states:
Some test instructions ask you to push the mattress “until it stops.” Usually that means pushing it until either:
the mattress retention system (such as mattress stops, straps, Velcro) engages and keeps you from pushing the mattress any further, or
the mattress stops against the opposite side rail(s).