If a nurse (or paramedic :-) ) is suctioning a patient' airway using in-line suctioning, the best method would be to hyperoxygenate the patient before disconnecting the ventilator.
It's necessary to hyperoxygenate a patient before suctioning because they will be decreasing their oxygen in-take the longer the suctioning takes place. This allows the nurse/medic to have a little extra time to finish suctioning and only have to do it once.
Agreement or concord happens when a word changes form depending on the other words to which it relates. It is an instance of inflection, and usually involves making the value of some grammatical category "agree" between varied words or parts of the sentence.